Fabrication and characterization of 3D-printed triboelectric nanogenerators

Kim, Donghoon Sungkyunkwan university 2018 국내석사

Recently, combination of internet platform and electronic devices, the technology of Internet of Thing(IoT) has been developed. As the recent trend is toward the miniaturization of electronic devices, the volume of the battery is also reduced. Over time, there are problems of battery life limit and treatment of depleted battery, so an additional electricity supply source is needed. Among the various alternatives, nanogenerators, the next generation of eco-friendly renewable energy technology, harvest the mechanical energy that is abandoned in everyday life and utilizes it as electric energy. It is an assistant to supply additional electrical energy to battery of electronic device for extending life of battery or even self-powering. Recently, triboelectric nanogenerators (TENGs) are new technology, generates electrical energy by using trioelectrification which occurs on the surface when two different materials are rubbed, which can utilize not only an energy source but also a sensor. Therefore, the diverse applications of environment, medical care and education are being actively studied in world wide. In this study, to improve the performance of conventional triboelectric nanogeneratrs, researched on the fabrication and characterization of high efficiency 3D-printed TENGs by using 3D printing technology which is currently popular in the 4th industry. Although there have been many studies on increasing the surface area in order to increase the output of the TENGs, there has been a limit to maximize the surface area due to device fabrication process. In the first study, introduced a 3D printer for dramatic surface area increase beyond the structural limitations, and fabricated the biomimetic villus structure. Using this, 3D-printed high efficiency TENG and dust adsorption system were designed, and the performance was confirmed experimentally. The next research was carried out to harvest not anthropogenic mechanical energy but the naturally occurring wind energy source. Wind energy is a representative eco-friendly energy provided by nature, and is present everywhere. So it is attracting great attention as a next generation energy source. In the second study, the 3D-printed wind energy harvester overcome the inefficient structural limitations inherent in conventional TENGs of harvesting wind energy source. In addition, to increase the output, ferroelectric power was mixed with the liquid resin. It is experimentally confirmed that the surface charge density can be increased by controlling the internal polarization of ferroelectric materials. The research on 3D-printed TENGs has confirmed the experimental results of both the structural approach and the material approach, and it has the strong advantages that the 3D printing process is simple, accurate and precise, and customized to the structure desired by the user. This is expected to make a great contribution to the research field of energy harvesting through ongoing research as an efficient 3D-printed complex structure for practical use in everyday life. Triboelectrification occurred to all each material, and studies are actively applied to diverse applications using electrostatic induction, but it has a limit of device fabrication process and surface patterning at the micro to millimeter level, so that the surface area was not considerably increased. In this research, we introduce the biomimetic villus structure with a DLP-type 3D printer, which is an additive manufacturing process with high resolution, for realizing the large increase of the surface area beyond the structural limitations, and imitate the intestinal villus structure that can be produced only by 3D printer. The surface area of 3D-printed biomimetic villus structure was increased by about 300% compared with the planar structure and in order to take full-contact of this increased surface area, PTFE powder was used as a triboelectric material, resulting that output charge were increased by 5 times and 4 times in the vertical mode and the rotation mode, respectively. In addition, a dust filtering system was utilized by using a lot of electrostatic charge formed between the surface of ABS and PTFE, and the dust of various size was efficiently adsorbed. Because of using polymer based ABS and PTFE ball, dust filter is stable and reusable easily, it is experimentally confirmed that the filtering efficiency of 41% is not decreased after by washing. As a result, we successfully validate that 3D-printed biomimetic villus structure with maximized surface area can be utilized as an eco-friendly dust adsorption system as well as a triboelectric generator, our work provides to practical approach for fabricating devices and utilizing applications. Since wind energy is a representative cleanest and sustainable energy source provided by nature, the technology of harvesting this source has a great potential and is highly attractive. In this research, we have developed a one-set 3D-printed wind energy harvester which is driven in freestanding mode by introducing 3D printing technology to overcome limitations of low durability and inefficient device structure of existing wind energy harvester. This 3D-printed wind energy harvester is made by 3D printing process and it can be used as TENG by simply adding electrodes and triboelectric material. Given an external wind energy source, the internal turbine rotates and drives with the triboelectric effect between the acrylic (photo-cured resin) and the kapton film. Given a wind energy source of 11 m/s, the maximum output power of 106 mW/m2 was measured. To increase the output, ferroelectric composite resin was fabricated by adding BaTiO3 powder, a ferroelectric material, to liquid photopolymer resin. Using this, the ferroelectric polarization can be controlled through an external electric field to increase the surface charge density of the 3D-printed triboelectric material. After the aligning polarization, the surface of photo-cured Acr:BTO composite material was adjusted more positively to obtain the output power density of 790 mW/m2 at 11 m/s (7.45 times increase than output of raw acrylic TENG). Therefore, using 3D printing technology, it is possible to precisely driven in freestanding mode, thereby harvest wind energy efficiently. In addition, using multifunctional photopolymer composite resin, output power of TENG can be enhanced by controlling polarization of ferroelectric material. This 3D-printed wind energy harvester is a promising technology to drive electric devices in the outdoor environments in a sustainable manner.

전력 전송 시스템해석을 위한 에너지기반 접근법

손형수 연세대학교 대학원 2002 국내석사

본 연구에서는 다모선 전력 계통을 위한 에너지 기반 전력 계통 해석으로의 새로운 이론적 접근을 제시한다. 에너지에 기초한 해석방법은 에너지 함수를 이용하여 시스템의 동적 방정식을 만들 수 있는 체계적인 방법을 제공하기 때문에 오랫동안 이용되어온 방법이다. 기계적 유사화(analogy)에 기반을 두고, 정밀한 에너지 해석을 통해 선로 저항이 있는 다모선 계통을 위한 정확한 에너지 적분 표현을 이끌어 낸다. 또한 선로 저항과 관련된 위치에너지 항, 즉 선로 서셉턴스와 관련된 에너지항, 그리고 콘덕턴스와 관련된 에너지항에 대한 물리적인 의미를 이해하기 위해 전력 전송 시스템과 유사한 단단한 막대기를 이용한 간단한 기계적 파워 전달 시스템을 제안한다. 마지막으로, Lagrange 방정식을 이용하여 전력 계통의 동적 방정식을 체계적으로 유도하고 제안된 전력 계통의 에너지 함수를 이용하여 정적 조류계산 식을 유도함으로써, 에너지 적분이 동적 및 정적 상태에 있는 전력 시스템에 대한 종합적인 정보를 가지고 있음을 보여주며, 제안된 접근 방법으로 전력시스템의 다이나믹스 해석을 위한 수학적, 그리고 이론적 도구를 매우 쉽게 사용할 수 있다. This paper presents a new theoretical approach to energy-based power system analysis for multibus power transmission systems. The energy-based approach has been preferred for long by the system engineers since it provides systematic procedures to set up the system dynamic equations based on the energy function. On the basis of mechanical analogy, an exact energy integral expression is derived for lossy multi-bus systems through rigorous energy analysis. A simple rigid rod model of mechanical power transfer system is introduced to address the physical meanings of potential energy terms associated with transfer conductances as well as transfer susceptances. Finally, This study shows that Lagranges equations can be well applied to power system analysis, providing systematic procedures to set up the power system dynamic equations and additionally the load flow equations for the static solutions with the proposed energy integral of power systems. This means that the energy integral has all information of power system dynamics in both static and dynamic states. The proposed approach enables us to utilize well-developed theories and mathematical tools for the analysis of power system dynamics, providing an easy access to power system analysis for general system engineers.

An analysis of Economy Barriers to Solar Photovoltaic Technologies Adoption in Bandung, West Java, Indonesia

ANDYASTIYA ANNISA SYLVANI 아주대학교 대학원 2019 국내석사

As a developing country, Indonesia needs a high energy supply but unfortunately, until 2017, Indonesia's main energy sources are still dominated by oil and gas. Realizing this, the central government of Indonesia has compiled a National Energy Policy that addresses energy management in order to realize energy independence and national energy security in supporting the sustainability of national energy development and one of them is by increasing the use of renewable energy. But in reality, many things prevent the use of renewable energy, one of which is from the economic side which can be divided into three main aspects: government policy, infrastructure, and consumer acceptance. Therefore, this quantitative research was formed to identify phenomena that occur in Indonesian society precisely regarding the process of adaptation of solar photovoltaic in the city of Bandung, West Java. There are at least three problems revealed regarding the use of photovoltaic technology: the obscurity of government regulations, the difficulty of technological adaptation and the lack of public interest in using photovoltaic technology as the main energy source. Therefore, a closer approach is needed to the community which can be started from the school stage regarding renewable energy information besides the government active role in advancing investment in the renewable energy sector and carrying out further development. In addition, government assistance such as soft loans may increase public interest in this technology.

Electric potential build-up by trapped electrons in magnetically expanding plasma

정경수 서울대학교 대학원 2020 국내박사

자기 노즐은 팽창하는 자기장 속에서 플라즈마 전자의 단열 팽창에 의하여 가속된 이온 빔을 추력에 활용하는 개념으로써, 이온 빔 중성화를 위한 음극의 추가적인 설치 없이 팽창하는 전자를 직접 중성화에 활용할 수 있다는 장점이 있어 차세대 전기 추력기로써의 가능성을 주목 받고 있다. 이온 빔 가속 에너지 관점에서 자기 노즐 장치의 효율은 폴리트로픽 방정식 (polytropic equation)을 통한 자기 단열 팽창에 의한 전자 냉각과 플라즈마 전위 구배의 관계에 의하여 결정된다. 따라서 자기노즐 장치에서 전자의 열역학적 상태에 대한 명확한 이해는 추력 효율에 직접적으로 기여한다는 중요성 아래 다양한 연구들이 수행되어 왔다. 자기 노즐 플라즈마에서의 전자 열역학적 상태에 대한 해석을 위해서는 전자 가스 계(system) 내부 에너지의 변화가 유동 주변(flexible surrounding)으로 정의된 자기장 및 전기장에 일을 수행한다는 전체 에너지 보존 법칙을 도입하여 자기적으로 팽창하는 플라즈마를 모사한다. 이 때 전자 열역학적 상태에 대한 기존 연구 그룹들의 실험 및 모델링 결과들은 플라즈마 내부에 존재하는 전위 장벽 혹은 자기 모멘트에 의한 전자 구속 여부를 기준으로 하여 시스템을 양분할 수 있게 한다. 전기적으로 구속된 전자 (trapped electrons)의 경우 전자의 단열 팽창은 전기장 구조 형성에 기여하는 반면, 탈출 전자 (escaping electrons)는 자기장 구조의 변경을 야기시키는 일을 할 수 있다. 따라서 자기 노즐 플라즈마에서의 전자의 열역학적 상태는 정전기적 구속 상태의 고려가 필수적임을 암시한다. 전자 계의 명확한 정의를 바탕으로 한 열역학적 상태 규명에 집중하여 수행된 선행연구들은 전자의 열역학적 상태와 자기 노즐의 효율간의 관계 연구에 대한 기반이 되었으며, 복잡한 플라즈마 물리 특성을 반영한 세분화된 연구를 필요로 한다. 자기 노즐 장치에서 플라즈마 생성이 전자의 에너지 및 방향 선택적 가열에 의하여 달성된다는 점에 착안하여, 전자의 열역학적 상태 변화에 의한 플라즈마 전위 구배 형성 연구가 전자의 방향성을 고려한 진단을 바탕으로 수행되어야함을 강조한다. 이를 위하여 전자 공명 가열(electron cyclotron resonance) 방식을 통한 플라즈마 생성원에서 인가 전력을 증가시켜 선택적으로 전자의 수직 방향 에너지를 변화시키면서 전자의 각 방향 성분 (자기장에 대해 수직과 수평) 의 전자 에너지 분포 함수 측정을 통하여 전자 열역학적 특성과 플라즈마 전위 구배 형성에 관한 연구를 수행한다. 흥미롭게도, 노즐 입구에서 전자의 수직 에너지 증가는 플라즈마 전위 구배 형성에 기여하지 못하였으며, 이는 전자 가열을 위하여 인가된 전력의 대부분이 탈출 전자의 수직 방향 에너지 상승에 기여했기 때문으로 해석된다. 수평 방향의 전자 에너지의 경우, 인가 전력이 증가 됨에 따라 노즐의 먼 영역에서 가열되는 특성이 관찰 되었으며, 이러한 가열은 플라즈마 전위의 절대값의 상승 효과를 일으켜 수직 방향의 구속 전자 그룹에 의하여 생성된 양극성 전기장을 감쇠하는데 영향을 주었다. 인가 전력에 따른 구속 전자의 수직 방향 성분으로부터 수평 방향 성분으로의 에너지 전달과 냉각을 포함한 변화와 플라즈마 전위 구배 변경 간의 상관관계는 구속된 전자가 단열 팽창을 통하여 전기장 형성에 기여 함을 증명 하였으며 다음과 같은 점들을 시사한다. 첫째, 전자 공명 가열을 활용한 자기 노즐 장치에서 이온 가속을 위한 전기장 형성에는 구속 전자의 가열이 직접적으로 이바지한다. 둘째, 구속 전자의 축 방향 열에너지의 변화와 전기장 변화는 폴리트로픽 지수가 5/3에 가까운 단열 팽창으로 설명된다. 셋째, 수직방향과 수평방향 간의 전자 에너지 교환은 노즐의 먼 영역에서 전기장을 약화 시킬 수 있으며, 따라서 이를 반영한 자기 노즐 연구에서의 모델링과 장치 설계가 필수적이다. 본 연구는 웨이브 가열에 의한 자기 노즐 플라즈마 생성시 전자 온도의 비등방성이 자기 노즐 효율에 직접적인 영향을 줄 수 있음을 강조하는 최초의 연구이다. 공학적 관점에서 이온 에너지의 효율적인 상승을 위하여 플라즈마 전위 조절을 통한 구속 전자의 비율 증가가 우선되어야함을 강조하며, 플라즈마 생성 영역에서 수평 방향 전자 에너지 가열을 통한 플라즈마 생성 방식에 대한 추가 연구를 통하여, 노즐의 먼 영역에서 자기 팽창에 따른 수직 방향에서 수평 방향으로의 에너지 전환이 최소화 될 수 있음을 암시한다. A magnetic nozzle leads the ion beam accelerated by the adiabatic expansion of plasma electrons in the expanding magnetic field for thrust. This concept has the advantage that the expanding electrons can be directly used for the neutralization of the ion beam without additional installation of a cathode for neutralizing the ion beam. Then, it is discussed as the next generation electric thruster. The efficiency of the magnetic nozzle apparatus in terms of ion beam acceleration energy is determined by the relationship between electron cooling and plasma potential gradient via a polytropic equation that can represent the adiabatic expansion in magnetically expanding plasma. Thus, previous studies have been conducted with the importance that a clear understanding of the electron thermodynamics in the magnetic nozzle contributes to the thrust efficiency. For the analysis of the electron thermodynamic state in the magnetic nozzle plasma, it describes the magnetically expanding plasma by introducing a total energy conservation law in which changes in the internal energy of the electron gas system work on magnetic and electric fields defined as flexible surroundings. The experiment and modeling results for the electron thermodynamics indicate that the system is enable to be classified based on the electron group trapped by the electric potential barrier or constant maximum magnetic moment. In the case of electrically trapped electrons, the adiabatic expansion of the electrons contributes to the formation of the electric field structure, while escaping electrons may work to cause a change in the magnetic field structure regardless of the electric field formation. Hence, in the electron thermodynamics of the magnetic nozzle plasma, it implies that consideration of the electrostatic confinement is essential. Previous studies focused on the identification of the electron thermodynamic states based on a clear definition of the electron gas system have been the basis for studying the relationship between the electron thermodynamics and the efficiency of magnetic nozzles, and require refined study that reflect complex plasma physics. Notice that the plasma generation in the magnetic nozzle apparatus is achieved by the electron energy and directional selective heating on them, it is emphasized that the study on the plasma potential gradient formation due to the change of the thermodynamic state of the electrons should be carried out based on the diagnosis considering the directional orientation of the electrons. The electron energy distribution function (EEDF) of each directional component is measured, while increasing the applied power to the plasma source by electron cyclotron resonance (ECR), and selectively changing the perpendicular electron energy. Interestingly, the increase in the perpendicular energy of the electrons at the nozzle throat did not contribute to the formation of the plasma potential gradient, which is interpreted because most of the power applied for the electron heating contributed to the rise in the perpendicular energy of the escaping electrons. In the case of the electron energy in the parallel direction, the electron heating in the far-field region of the nozzle is observed as the applied power increased, and this heating induces the synergistic effect of the absolute value of the plasma potential, resulting in the attenuation of the ambipolar electric field generated by the trapped electron group in the perpendicular direction. The correlation between the plasma potential gradient change and the change of electron cooling and energy transfer from perpendicular to parallel component of the trapped electrons according to the applied power proves that the trapped electrons contribute to the electric field formation through the adiabatic expansion and suggests the following points. First, heating of trapped electrons directly contributes to the build-up of an electric field for ion acceleration in a magnetic nozzle utilizing ECR heating. Second, the change in the paraxial thermal energy of the trapped electrons and the change in the electric field are demonstrated by the adiabatic expansion of which the polytropic index is close to 5/3. Third, the electron energy transfer between the perpendicular and parallel directions can interrupt formation of the electric field in far-field region. Therefore, modeling and device design in the magnetic nozzle research that reflects the above perspectives are essential. This study is the first to emphasize that the anisotropy of electron temperature can directly affect the magnetic nozzle efficiency when generating magnetic nozzle plasma by wave heating. From the engineering point of view, it is important that the ratio of trapped electrons should be prioritized to abundant via plasma potential control for efficient increase of ion energy. Through the further research on the plasma generation method such as parallel electron energy heating in the plasma generation region, this suggests that energy conversion from the perpendicular to the parallel direction due to magnetic expansion in the far-field region can be minimized.

오피스 건물의 최적 에너지 절약을 위한 설비 운영시스템 개선 방안에 관한 연구

김정석 단국대학교 대학원 2011 국내석사

대부분의 인간 활동이 이루어지는 공간을 제공해주는 건축물은 쾌적한 거주환경을 제공해주기 위해 여러 가지 설비(냉난방, 전기, 조명 등)를 필요로 하며 이 과정에서 상당한 에너지가 소비되고 있다. 인공적인 환경물로써 건축물은 지구 전체 원자재의 40%를 소비하는 동시에 CO₂를 35% 이상 배출함으로써 전 세계 에너지의 50% 이상을 사용하고 있다. 국내에서는 최근 이와 같은 움직임의 건축적 대응 전략으로서 2001년 `건축에너지 효율등급 인증제도'가 시행되었으며 이후에 해외 친환경건축 인증제도 처럼 통합된 인증제도가 도입되는 시점이다. 이와 같은 시점에서 건축물의 효율적 관리를 통한 에너지 절감은 장/단기적인 국가 정책에 부합하며 건축물의 비용을 줄일 수 있어 경제적으로 궁극적인 효과가 기대된다. 이에 본 연구에서는 건축물 유형 가운데 오피스 빌딩의 유지관리 비용의 객관적 지표가 되는 에너지 관리체계 및 평가방법을 제시하고, 건축물 에너지 효율등급 인증제도와 관련하여 오피스 빌딩의 리모델링 및 운영 시 에너지 절감 방안에 관한 기초적 연구로 건축물 에너지 사용량의 절감 방안을 도출하여 건축물 에너지 효율등급의 상향조정을 위한 방안을 제시한다. 국․내외 건물에너지 절약기준 및 이론적 고찰을 통하여 건축물 에너지 관련 정책 및 국외 오피스 빌딩의 에너지 관리현황을 조사하며, 선진사례를 통하여 벤치마킹분야 및 국내적용 방안에 관하여 조사하였다. 그리고 일정 규모 및 동일 용도를 가진 오피스 빌딩 3곳을 선정하여, 건축물의 현장조사를 통하여 설비 시스템, 자동제어 관제점, 및 에너지 사용량을 통하여 건축물의 에너지 효율등급을 산정하였다. 또한, 현장 조사를 통하여 오피스 빌딩의 운영 및 설계 단계에서의 문제점을 도출하였으며, 문제점은 시뮬레이션을 통하여, 건축물 리모델링 시 외피 교체 및 설비시스템 운영에 따른 건축물의 사용에너지 절감량을 통하여 오피스 건물의 에너지 효율등급 상향 조정 방안을 제시하였다. The buildings that provide a comfortable living environment where majority of human activities are taken place need various facilities such as HVAC, electricity and lighting which consume considerable energy. As the artificial environment, buildings use 40% of global raw materials and more than 50% of global energy while exhaust over 35% of CO₂over the world. In 2001, "Building Energy Efficiency Rating System" was implemented in our country to reduce the consumption of energy usage in buildings. Now, we are at the time of introducing integrate certification system just as overseas "Green Building Certification System" Reduction of energy in buildings by efficient management of energy is consistent with long/short-term national policies and the following economic effects are expected. In this study, I suggested the energy management system and its assessment method which are objective indicators of cost of building maintenance. Related with "Building Energy Efficiency Rating System", I did a basic research on energy-saving measure is applicable to the office building while its remodeling and operating. I also gave a building energy-saving measure to upgrade the building energy efficiency rating. In the early stage, I did some research on policies of building energy and situation of energy management of overseas office building through building energy-saving standard and its basic theory from home and abroad. After then, I did research on realm of benchmarking and domestic application method. And a certain size and same utilization of three places in an office building were selected to search the equipment system, automatic control and usage of energy by site survey for the purpose of estimating the building energy efficiency rating. In addition, I found out the problem of the operation and design stage of the office building and gave a measure of upgrading the building energy efficiency rating according to the amount of energy savings with building envelop replacement and operation of equipment system.

실시간 부하패턴 기반 산업용 수용가 ESS 운영 알고리즘

홍종석 숭실대학교 대학원 2016 국내박사

최근 제7차 전력수급기본계획에서는 과거 재정지원중심의 수요관리에서 ESS, EMS, 네가와트 등 ICT기반 에너지신산업을 활용하여 시장친화적 수요관리시스템으로 전환하여 2029년까지 최대전력을 12%, 전력소비량을 14.3% 감축할 계획을 발표하였다. 이를 통해 예비력이 부족한 수급비상 상황뿐만 아니라, 상시 피크를 억제하여 발전․송배전 설비건설 등 사회적 비용감소를 얻고자 한다. 제2차 에너지기본계획에서는 대규모 송전건설 최소화 정책방향이 가시화되도록 구체적인 분산형 전원 적용기준을 제시하였으며, 분산형 전원 확대계획과 여타 에너지 정책과의 정합성 확보 및 분산형 목표 달성(‘35년 발전량의 15%)을 위한 정책방안을 강구하고 있다. 이에 따라 분산형 전원의 보급 목표를 지속적으로 증가시킬 계획이다. ESS는 출력안정화 뿐만이 아닌 최대 전력수요의 저감 및 에너지 소비 시간을 이동할 수 있는 기능 등을 갖추고 있어 향후 전력시스템에 다양한 응용분야로 발전해나갈 수 있을 것으로 예상되며, 그 필요성이 더욱 부각되고 있다. ESS를 도입함에 있어서 매체의 기술적인 발전도 중요하지만 이를 도입하고자하는 응용분야에 맞는 알고리즘을 수립하는 것이 매우 중요하다. 전력계통에서의 일반적인 전력수요패턴의 특징은 낮 시간대에 전력소비가 많으며, 심야시간에 전력소비가 적은 형태를 가진다. 하지만 부하의 종류마다 세세하게 보면 산업용 수용가의 경우에는 제조업 특성상 전력소비가 24시간 내내 변화가 없는 패턴을 가지며, 주택용 수용가는 아침과 밤에 최대소비전력이 나타나는 패턴을 갖는다. 이와 같이 전력소비패턴이 다른 수용가마다 ESS를 도입하기 위해서는 이에 맞는 알고리즘이 필요할 것이다. 하지만 수용가의 전력소비패턴이 일정하지 않다면 과거의 부하데이터를 기반으로 하는 예측 방법이 오히려 경제적인 손실을 야기할 수 있다. 이러한 이유로 본 논문에서는 과거의 부하데이터를 이용하여 전력소비패턴이 얼마나 균일하게 나타나는지를 판단할 수 있는 기법을 제안하고자 한다. 대표적인 방법인 RRMSE는 미국의 PJM에서 부하의 시장 참여를 목적으로 사용하고 있으며, 국내에서는 최근에 전력거래소에서 채택하여 적용하고 있다. 전력소비패턴이 균일하지 않다는 것은 그만큼 예측이 어렵다는 것이기 때문에 이와 같은 방법을 도입하였다. 또한 위에서 산업용과 같이 전력소비패턴이 균일하지 않은 수용가에 ESS를 도입하였을 때 필요한 알고리즘을 제시하였다. 알고리즘의 성능 비교는 전기요금을 기반으로 한 경제성 평가를 통하여 타당성을 입증하였다. Recently, the "7th Basic Plan for Long-term Electricity Supply and Demand" has been released by the South Korean government. The plan suggests reducing 12% of peak demand and 14.3% of electrical energy usage by changing Demand Side Management (DSM) from financial support based system to ICT-based Energy-related New Industries, such as ESS, EMS and Negawatt by 2029. It will help not only to preserve the emergency cases by losing operating reserves but to reduce construction cost by suppresses the peak loads on time. In the “2nd Plan for large-scale energy transmission construction”, The specific application criteria on distributed resources is suggested and also the strategy for the expansion of distributed resources, matching with other energy policies and goals (15% of 35 years’ development) is provided. Accordingly, it plans to increase the supply of distributed resources constantly. Constant supply of renewable energy is a factor of instability for supplying output power in the respect of the grid. The energy storage system has features, such as the ability to move the reduction and energy consumption of time for the maximum power demand, not only stabilizing power output, and it is expected to evolve in a variety of applications of the power plants in the future. Therefore, there is a growing need for the system. As introduced, the technical development of the energy storage medium is important, and it is also important to develop an algorithm for the application to be introduced into them. The power demand pattern on the power system has common features, like a large amount of the power consumption in the daytime, and a small amount of the power consumption late at night. However, when looking at each type of load carefully, the industrial customers have the pattern that has not changed for 24 hours by the nature of manufacturing, On the other hand, residential customers have the pattern of a the maximum power consumption that appears in the morning and at night. In this way, to introduce the energy storage into different customers, the appropriate algorithm is needed. However, if the power consumption of the customers has the irregular pattern, the prediction method based on historical data of the load may cause more economical damage. For this reason, in this paper, we propose a technique to determine how to appear the uniform power consumption by using the history of the load data pattern. The typical method of RRMSE (Relative Route Mean Square Error) is used for the purpose of the load’s participation in the PJM (Pennsylvania-New Jersey-Maryland) market of the United States. It has been recently adopted and applied to in the KPX (Korea Power Exchange). The power consumption pattern is not uniform and the prediction is difficult. Thus, this method is introduced. In addition, in case of introducing the energy storage device into the power consumption pattern whose customer is not uniform, like the industrial customers, as presented above, the appropriate industrial algorithm is suggested. Comparing the performance of the algorithm has been justified by the economic evaluation based on the electricity bill.

에너지 需給 및 展望에 관한 硏究 : 韓國에너지資源 需給展望을 中心으로

박시영 釜山産業大學校 貿易大學院 1985 국내석사

Although eight years have passed since the oil shock took place, today we cannot emphasize the importance of the oil problem too much. 1. The characteristics of the structure of energy demand in Korea are as follows: First, the price elasticity of total energy demand is conciderably small in comparision with that of foreign countries. Second, the income elasticity of total energy demand is much larger than that of foreign countries. Third, in a time lag that the fluctuations of energy price and income have an effect on the energy consumption, the main advanced countries nearly show the immediate response. But the rise and fall effects of energy consumption in Korea happen for the first time after one or two years elapsed. Fourth, while energy and capital have the easy substitutional relation each other comparatively, energy and labor have the relation difficult to be substituted. Fifth, the manufacturing sector in Korea has a rigid structure that the substitution between the source of energy is extremely small in the energy demand. Sixth, when we view the national economy as a whole, coal and oil have the relation to be substituted very easily, but electric power and other source of energy don't have the relation to be substituted at all. Seventh, the substitution between oil products cannot be compared with Korea because of the absence of foreign cases. But when we analyze the inferred results, we can see that because the substitution relations between each manufactured goods get entangled, the adjustment policy of price and the demand of the amount of materials reflect the fact hard to give satisfactory results actually. 2. The energy supply and the development of substitute energy The structure of energy supply in Korea has the prominent characteristics as follows in comparision with that of the advanced conturies and the main developing countries. First, the degree of external dependence of energy supply is being deepened. The degree of energy self-support in Korea decreased sharply from 53.2% in 1970 to 27.4% in 1979. Therefore, the degree of external dependence of energy supply is being deepened seriously. Second, the proportion that the oil occupies in the structure of energy supply is increased more and more despite of the two round of oil shocks. The degree of oil dependence in Korea was sharply increased from 46.5% in 1970 to 61.0% in 1979 and has been sustained 60% since 1980. This fact results from the rapid increase of oil demand, the maintenance of economic structure to consume lots of oil and the small substitution between the source of energy by the continuity of the rapid economic growth. On the and hand, for lack of capital and technique in comparision with the advanced countries in the development of substitute energy, Korea doesn't make much efforts about the source of non-consumption-recoverable substitute energy like the salar heat. 3. The long-term prospect of energy demand-supply. The long-term demand-supply programs of energy in Korea have the characteristics as follows. First, the rate of economic growth and an increasing rate of energy price assumed for the prospect of demand and supply of energy are very optimistic. While an annual everagy growth rate of economy by 2,000 years is assumed at a high rate of 8 to 10%, an annual averagy increase rate of energy price is comparatively assumed at a low rate of 5 to 11%. On the other hand, as compared with the assumption of growth rate of demand-supply prospect attempted in the foreign countries, that of the advanced countries is assumed at a rate of 1 to 4%, that of the developing countries at a rate of 2.8 to 6.3%, and the in-creasing rate of energy price at a rate of 11 to 15%. Second, as a natural recult of these optimistic assumptions about the most important income and price determining the energy demand, if follows that the annual average rate of total energy demand in Korea is expected to reach 9.2 to 10.3% by 2,000 years. On the contrary, the annual average rate of energy demand in the advanced countries and the developing countries is respectively expected to reach 1.5 to 2.4% and 5.3 to 6.2% by 2,000 years. Third, while the relative importance that the oil occupies in the total energy demand-supply in the year 2,000 is expected to reach 38% and 26% respectively in case of the world as a whole and all the members of IEA (International Energy Agency), in case of Korea it is lower than the present level, but is still expected to reach a high rate of 43 to 54%. 4. The program for rationalization in the energy demand supply. When the economy in Korea faces the enrgy crisis and fries to establish the rational structure of energy demand-supply to be able to cope with it successfully, the above several suggestive points will have to be considered. To cope with the energy crisis to come in the future flexibly, the structure of energy demand and the economic structure with lost of weaknesses should be improved without delay. The adjustment of such structure of energy demand-supply will have to be projected in the following four directions. First, in the side of energy demand, the price elasticity should be larger than the present situation and the income lasticity should be smaller in a big jump. Because it is desirable that the price elasticity becomes more than one and the income elasticity becomes less than one at all, though the structure of energy demand isn't necessarily rational. And under the structure of energy demand in which the fluctuation of energy price has an effect on the energy demand through the intermediate course of the income change-that is, rather the income machanism than the price machanism governs the demand-supply edjustment is very difficult through the price policy in short term, and in the long term there is a lot of possibilities that the energy crisis can press the income severely. Second, the technical renovation should be encouraged in order that the flexible substitution can be made between energy and other factors of industry, between the sources of energy. In particular, in order to increase the energy substitution of labor, the qualitative level improvement of labor force is essential, and the production technique or the introduction of production process that each source of energy in the manufacturing sector can be substituted and used easily should be more expanded. Third, in the side of energy supply the use of oil substitute energy like coal and gas and so on should be more promoted and the relative importance of it should he increased. To lead the use of substitute energy, the readjustment work of mode of production and mode of life should be also kept abreast socio-economically. Fourth, in relation to the energy-saving economic structure, the heat efficiency of energy not far reaching the level of the advanced countries should be increased in order to decrease the proportion of the lost energy extremely and to complete the economy on energy consumption.

Essays in public economics: Reduction of pollution through enforcement of emissions limits and reduction of household energy use

Nieman, Scott William The University of Wisconsin - Madison 2001 해외박사(DDOD)

This dissertation consists of two essays that examine potential ways to reduce pollution through economic incentives. The first essay uses plant-level data to examine the effects of inspections and enforcement actions on compliance with water pollution permits by plants in the pulp and paper industry. Unlike studies using data from earlier time periods, this paper finds that previous inspections have only small effects on current compliance. However, when the effects of different types of inspections are examined, non-routine inspections are found to lead to a lower rate of violation. In order to determine whether inspections affect compliance only through the threat of subsequent enforcement actions or whether they have a direct effect on compliance, a two-stage model of enforcement and compliance is estimated. The results show that plants more likely to face enforcement for violations are less likely to be in violation, suggesting that the threat of enforcement actions is an effective deterrent to noncompliance. Additionally, even after controlling for the effects of enforcement actions, non-routine inspections are found to increase compliance. The second essay examines energy consumption among apartment residents whose energy costs are included in their rent. Because these tenants do not face the marginal cost of their own energy use, they have limited incentive to conserve energy. Explanations for the existence of such rental agreements fall into two categories: tenants value the arrangements more than the resulting increase rent, or landlords prefer such contracts over paying the extra costs of metering apartments individually. Data from the Residential Energy Consumption Survey and the American Housing Survey are used to estimate the additional energy use by tenants in utility-paid apartments, and the additional rent paid for those apartments. Results indicate that market rents for utility-paid apartments are higher than for otherwise similar metered apartments. However, this difference is not large enough to offset the increased energy use by tenants of such apartments, supporting landlord-side explanations for the persistence of these seemingly inefficient rental contracts.

에너지개념에 기초한 액상화 평가방법에 관한 연구

유정선 연세대학교 대학원 2006 국내석사

지반의 액상화 저항강도를 산정하기 위한 실내시험 수행시 대부분의 경우는 실지진력을 이용하기보다는 등가전단응력과 등가반복 재하횟수로 표현된 정현파의 진동하중을 사용한다. 등가전단응력 개념은 지진으로 인해 발생하는 전단응력 중에서 최대전단응력의 65%를 정현파로 적용시키는 것으로 실제 지반내의 불규칙한 지진력과는 상당한 차이가 있다. 본 연구에서는 지진시 포화 사질토의 거동특성을 연구하기 위하여 지진력과 같은 불규칙한 전단하중을 재현할 수 있는 정밀한 진동삼축시험기의 실험결과를 이용하였다. 진동삼축시험시 작용하는 축하중에 따른 액상화 발생 특성을 비교․분석하기 위해 실지진 시간-가속도 이력을 이용한 진동삼축시험 결과 및 기존의 등가전단응력 개념에 기초한 정현하중의 진동삼축시험 결과를 수집하였다. 정현하중의 경우에는 초기 하중이 굉장히 크고 규칙적인데 비해 실지진 하중은 처음에는 작은 불규칙한 동하중이 가해지다가 어느 순간 갑자기 큰 하중이 가해지는 경우가 많다. 따라서 정현하중을 대체 할 하중으로 실지진하중과 유사한 거동을 보이는 선형증가쐐기하중을 사용한 진동삼축시험도 수행하였다. 실험에 사용된 시료는 액상화가 발생하기 쉬운 주문진 표준사를 선택하였다.지진파형별로 하중에 따른 과잉간극수압의 발생 경향을 나타내었고, 동적 실내실험 결과로부터 입력하중 형태에 따른 액상화 저항강도를 에너지 개념에 의하여 산정하였다. 액상화 저항강도를 응력-변형률 곡선(hysteresis loop)으로부터 산정한 누적소산에너지양으로 나타내었다. 하중형태에 따른 누적소산에너지를 비교하였으며 이를 바탕으로 정규화 에너지 발생치와 정규화 에너지 저항치를 산정하여 액상화 평가를 수행하였다.시간에 따른 과잉간극수압을 비교한 결과 정현하중에 비해 실지진하중과 선형증가쐐기하중의 과잉간극수압 발생 형태가 유사하였다. 또한 액상화 발생시의 에너지를 비교한 결과 실지진하중과 선형증가쐐기하중의 경우에는 대체로 비슷한 소산에너지에서 액상화가 발생하였다. 정현하중의 경우에는 실지진하중과 선형증가쐐기하중에 비해 3배 이상의 에너지에서 액상화가 발생하였다.정현하중의 액상화 안전율은 실지진하중 및 선형증가쐐기하중의 경우에 비해 상대적으로 큰 값을 나타냈으나 선형증가쐐기하중이 가해질 때의 안전율은 실지진하중이 가해질 때의 안전율과 큰 차이를 보이지 않았다. 이는 등가전단응력개념에 기초한 정현하중을 이용해 액상화 평가를 수행하는 데는 문제가 있으며, 선형증가쐐기하중을 통한 액상화 평가가 실제 지진파에 의한 액상화 거동을 보다 잘 평가하고 있음을 보여준다. Liquefaction potential is evaluated by comparing the liquefaction resistance strength of soil with the cyclic shear stress generated in the soil layer during earthquakes. Instead of irregular earthquake loading, the equivalent uniform stress concept presented by Seed and Idriss(1975) has been applied to evaluate the liquefaction resistance strength. However, the liquefaction strength of soil based on the equivalent uniform stress concept cannot reflect the dynamic characteristics of the irregular earthquake motion. Thus the cyclic triaxial test was conducted by using increasing wedge loading to simulate the actual earthquake loading.Liquefaction characteristics of saturated sand under various dynamic loadings such as sinusoidal loading, increasing wedge loading, and real earthquake loading were investigated focusing on the dissipated energy. From the results of cyclic triaxial test, liquefaction resistance strength was calculated by the concept of energy according to the form of input loading. Liquefaction resistance strength was expressed in accumulated dissipated energy calculated from stress-strain curve(hysteresis loop).The dissipated energy according to loading type was compared and the energy-based evaluation was proposed. The procedures are presented in terms of normalized energy demand(NED), normalized energy capacity(NEC), and factor of safety, where NED is the load imparted to the soil by the loading(both amplitude and duration), NEC is the demand required to induce liquefaction, and factor of safety is defined as the ratio of NEC and NED.It is found that energy calculated by liquefaction occurred in similar dissipated energy in case of actual earthquake loading and increasing wedge loading. However, the energy by sinusoidal loading is 3 times as large as others.The factor of safety against liquefaction by increasing wedge loading is similar to actual earthquake loading. But the factor of safety against liquefaction by sinusoidal loading is relatively larger than the others. Based on all of these test results, the increasing wedge loading can reflect the liquefaction behavior under real earthquake loadings more effectively than sinusoidal loading based on equivalent uniform stress concept.

Energy-optimal Planning and Control of Autonomous Underwater Vehicles Under Ocean Currents

Yang, Niankai ProQuest Dissertations & Theses University of Mich 2022 해외박사(DDOD)

Autonomous underwater vehicles (AUVs) can broaden the scope of underwater deployments thanks to their high level of autonomy. Yet, one of the major challenges in using AUVs for long-range or deepwater missions is the limited vehicle endurance, i.e., the ability to consistently conduct missions. This dissertation develops advanced energy management strategies involving energy-optimal planning and control to improve the AUV operational energy efficiency, extending AUV endurance. The proposed planner takes into account the effect of future vehicle motion on the flow prediction accuracy to ensure good robustness in energy saving. Given the planned references (e.g., waypoints or paths), controllers are proposed to further enhance energy-saving performance by considering the vehicle dynamics and real-time ocean current information.For performance evaluation/quantification, a virtual test-bed is developed based on the test-bed vehicle, DROP-Sphere. The virtual test-bed includes a six-degrees-of-freedom vehicle motion model and an empirical thruster energy consumption model fitted based on the experimental data of DROP-Sphere. Control-oriented ocean current and vehicle models are further derived from the virtual test-bed to facilitate planner and controller designs.Optimal path planning requires accurate flow predictions to ensure robust energy-saving performance. Active flow perception, which refers to strategies that optimize vehicle actions so that the flow information collected along the vehicle path reduces uncertainties in flow prediction, is leveraged to develop the energy-optimal planner. Assuming negligible unmodeled dynamics in the control-oriented ocean current model, the flow prediction uncertainty is evaluated by the Cramer-Rao (CR) bound of estimated model parameters. The planner is established by minimizing the cost associated with the estimated propulsion energy and CR bound. Simulations demonstrate improved robustness in energy saving by considering the trade-offs between exploration and exploitation of flow information during path planning.To track planned waypoints with enhanced energy efficiency, an economic model predictive control (EMPC) is proposed. The EMPC optimizes stage costs capturing the control energy consumed within the prediction horizon and a terminal cost approximating the energy-to-go, i.e., the energy required to reach the desired waypoint from the end of the prediction horizon. To retain the optimality achieved by globally-optimized solutions with reduced complexity, the energy-to-go is formulated based on the maneuvering characteristics observed in trajectory optimization solutions. Further analysis reveals that the proposed EMPC can balance the trade-offs among energy components spent for vehicle surge, heave, and yaw controls.For following planned paths with reduced energy use, a robust energy-optimal controller is proposed, taking setpoint computation and tracking steps to achieve the three-dimensional (3D) path following. The surge velocity, heave velocity, and pitch angle setpoints are optimized by minimizing vehicle propulsion energy considering the uncertainty set defined by the state estimate and its uncertainty. A line-of-sight-based guidance law is established to compute the yaw angle setpoints, which integrates direct and indirect drift angle compensation for reduced path-following error and path-convergence time. Two setpoint-tracking MPCs are designed to control horizontal and vertical vehicle motion with a small computational overhead. It is shown that the proposed controller can optimize the vertical motion in 3D path-following under ocean currents for increased energy savings.