Energy Dissipation Characteristics Modelling for Hot Extrusion Forming of Aluminum-Alloy Components

Hongcheng Li,Yuanjie Wu,Huajun Cao,Feng Lu,Congbo Li 한국정밀공학회 2022 International Journal of Precision Engineering and Vol.9 No.6

The hot extrusion forming process is widely used to process aluminum-alloy components in both the automobile and aircraft manufacturing industries. Since it involves pushing the material through the die at increased temperature, it is very energy-intensive despite requiring less blank material allowance. During hot extrusion forming, the multi-stage dynamic conversion of electricity, mechanical energy, and hydraulic energy to heat results in high energy dissipation. In order to improve the power and energy conversion efficiency of hot extrusion forming process, it is necessary to identify the energy dissipation characteristics. The transfer and conversion paths of the electrical, mechanical, and hydraulic energy from the motor to the hydraulic cylinder were firstly depicted based on the motion cycle of the extruder. A bond graph-based energy dissipation model was then proposed for dynamically identifying the energy-saving potentials. The energy dissipation model integrated the power bond graph sub-model of energy conversion elements such as motor, pump, hydraulic valve group, and hydraulic cylinder. These power bond graph sub-models were separately developed to find the energy dissipation state equations of energy conversion elements. An experiment was carried out using data obtained from the energy management system to validate the bond graph-based energy dissipation model. The results have shown that the power and energy conversion efficiency of hot extrusion forming is primarily controlled by the parameters such as extrusion velocity and extrusion force. Both the higher extrusion velocity and lower extrusion force will reduce the power and energy conversion efficiency. An optimal combination of extrusion velocity and pressure can achieve the lowest energy consumption per unit product.

Study on Strain Energy Transfer and Efficiency in Spatial Micro-forming of Metal

Zhaojie Chen,Jin Xie,Quanpeng He,Dongsheng Ge,Kuo Lu,Chaolun Feng 한국정밀공학회 2024 International Journal of Precision Engineering and Vol.11 No.2

In spatial micro-fabrication on metallic surface, the mechanical machining consumes material shear deformation energy, while the laser machining energy is greatly converted into material melting heat energy. In production, the micron-scale material-removal machining requires the CNC system to long-time tool path interpolation for high energy-consumption. According to dynamics and kinematics of metallic plastic deformation, a strain energy transfer is proposed to deform micro-topographic shapes by differentiated surface stress. The objective is to realize the precision forming of spatial microstructure surface through the strain energy conversion and conservation. First, the energy transfer and strain variations were modelled in relation to die curvature radius, workpiece thickness, initial microstructure angle and depth. Then, the strain energy consumption was investigated in relation to material properties, die movement, and micro dimensions. Finally, it was applied to industrial cold-pressing. It is shown that the strain energy of a single microstructure formation transfers from centre to outer part. The spatial microstructure forming may change from diversified strain stage to uniform strain state with the highest energy efficiency at a critical strain energy, while the surface roughness remains unchanged. Under the strain energy transfer, the microstructure shape changes with increasing energy consumption to a critical value. The metal compressive strength, die curvature radius and workpiece thickness promotes energy consumption, while descending velocity promotes processing efficiency. By controlling the energy conversion, the spatial microstructure sizes may be fabricated with an error of about 1.0% and the energy consumption of about 10 mm3/J. In industrial production, it contributes high energy efficiency without coolant pollutant in contrast to mechanical machining and laser machining. As a result, the strain energy conversion and conservation may be regarded as an evaluation for an eco-friendly micro-fabrication.

자연과학편 : 멀리뛰기 발구름 구간에서의 에너지 흐름과 발구름 동작의 운동학적 특성 분석

류재균(JaeKyunRyu),김혜영(HyeYoungKim) 한국체육학회 2008 한국체육학회지 Vol.47 No.4

이 연구는 에너지 흐름을 중심으로 멀리뛰기 발구름 동작의 운동학적 특성을 분석하는 데 목적이 있다. 2002년 부산아시안 게임 결승전을 분석한 22개 점프사례를 운동학적 자료로 이용하였으며, 발구름 동작에서의 에너지 손실과 에너지 변환지수(transformation index) 그리고 발구름을 통해 수평운동에너지가 탄성운동에너지로 전환된 비율인 전환효율(conversion efficiency) 등을 조사하였다. 이와 같은 동역학적 요인들을 이용하여 발구름 특성에 맞는 적절한 도약각도의 범위와 가능한 최대점프거리를 구하였고, 에너지 손실이 작아야 점프거리가 증가하는 게 아니라 선수마다 적절한 에너지 손실과 변환지수의 조합이 존재한다는 것을 제안했다. 또한 전환효율이 클수록 경기력이 좋은 게 아니라 점프력이 우수한 남자 선수일 경우 전환효율보다 발구름다리의 충격량과 근력과 같은 점프력을 강화해야 하고, 도움닫기 속도가 빠른 선수는 전환효율이 클 때 경기력이 우수하였다. 남자보다 도움닫기 속도가 늦고 도약각이 큰 여자선수들의 경우에도 선수들의 특성에 맞는 전환효율과 점프력이 요구되었다. 따라서 이 연구는 멀리뛰기 발구름 동작에서 선수들의 운동학적 특성을 고려한 에너지 변화를 동역학적 요인을 통해 정량적으로 제시하였다. The goal of this study was to analyze the take-off kinematic characteristics for long jumpers by way of mechanical energy flow. The data for this study was recorded at the 2002 Track and Field final in Busan Asian Game. The 22 long jump trials were used as kinematic data. Energy loss, energy transformation index and elastic energy conversion efficiency were investigated during take-off motion in long jump. The maximum jumping distance was determined by the optimal take-off angles through dynamical variables. From this study we found out that the maximum jumping distance was not obtained by reducing the energy loss but by obtaining the proper combination of both energy loss and transformation index. It can be seen in the men's elite groups that athletes with strong jumping ability can improve the jumping performance by strong take-off impact and muscle strength. The athletes with faster running approach can improve the performance by increasing the conversion efficiency. In the women's elite groups, the proper the conversion efficiency and jumping ability were required in order to improve the jumping distance.

4차 산업혁명 기술의 에너지기기 융복합 추세에 따른 에너지효율관리제도의 변화방향에 관한 연구

하윤희 ( Yoonhee Ha ),김은지 ( Eunji Kim ) 한국자치행정학회 2020 한국자치행정학보 Vol.34 No.1

The integration of the smart technologies to energy-use devices is bringing forth a revolutionary change in the practices of energy management. This trend calls for changes in policy and institutional settings with regard to energy management. This study focuses on a new pathway for the energy efficiency management system in response to this great transformation in the energy technology. Specifically, it reviews major issues of energy efficiency management system due to the smartization of energy-use devices and the responses of major countries to this change. Also this study draws policy implications in order to establish the mid- and long-term energy efficiency management system under this technical transformation. Major countries are designing a new regulatory and policy structure to adapt the existing energy management system to the current technical change. Although Korea is leading the global market in the smart home appliances and communication industry, it is far behind in the institutional response to a new trend in energy technologies and markets. To fill the gap and ultimately to lead this transformation, actions are urgent in the policy side. Various formative and incentive institutions and regulations should be examined to find out desirable regulatory and policy framework for the Korean context. Active engagement in the international technology standardization initiatives over related equipment is also important. Including smart energy devices in target items for the energy efficiency management system is a crucial avenue to promote advance in related technologies and achieve actual energy saving. To make it happen, researches on measuring energy efficiency effects should be carried out as soon as possible.

압전 진동 에너지 수확 장치의 에너지 변환 효율에 대한 고찰

김재은(Jae Eun Kim) 대한기계학회 2015 大韓機械學會論文集A Vol.39 No.5

압전 진동 에너지 수확 장치의 설계 및 성능 평가 시 에너지 변환 효율을 고려하는 것은 매우 당연하다. 본 연구에서 고려하는 에너지 변환 효율은 부하 저항이 부착된 압전 진동 에너지 수확 장치에 입력되는 가진 진동 파워 대비 전기 출력 값으로 정의된다. 기존의 연구에서는 근사적으로 임피던스 정합된 부하 저항에서의 전기 출력을 고려한 반면, 본 연구에서는 최적의 임피던스 정합 값을 사용하여 새롭게 에너지 변환 효율 식을 유도하였다. 유도된 식의 타당성을 검증하기 위해 3 개의 서로 다른 전기-역학 연성 계수 값을 갖는 진동 에너지 수확 장치에 대한 유한 요소 해석 결과를 이용하였다. 또한, 부하 저항의 임피던스 정합 방법의 차이에 따른 에너지 변환 및 변환 효율 특성을 살펴보았다. To properly design and assess a piezoelectric vibration energy harvester, it is necessary to consider the application of an efficiency measure of energy conversion. The energy conversion efficiency is defined in this work as the ratio of the electrical output power to the mechanical input power for a piezoelectric vibration energy harvester with an impedance-matched load resistor. While previous research works employed the electrical output power for approximate impedance-matched load resistance, this work derives an efficiency measure considering optimally matched resistance. The modified efficiency measure is validated by comparing it with finite element analysis results for piezoelectric vibration energy harvesters with three different values of the electro-mechanical coupling coefficient. New findings on the characteristics of energy conversion and conversion efficiency are also provided for the two different impedance matching methods.

프랑스의 스마트빌딩 법제의 쟁점에 관한 연구

정재도 한국부동산법학회 2019 不動産法學 Vol.23 No.1

In general, the conceptual elements of smart building are as follows.: ‘intelligent building system with information communication function and automatic control system’, ‘providing and managing energy, lighting, disaster prevention, water resources, heating, ventilation, and air conditioning(HVAC) based on smart sensors and control systems.’ Recently, however, the most discussed issues related to smart buildings are the energy efficiency of buildings, the use of new renewable energy, and the reduction of CO2 emissions. In addition, the issue of protecting personal data is also important. In France, Smart Building is closely related to the energy efficiency improvement of buildings, which is the main goal of ‘Energy Conversion Law for Green Growth’(Loi relative à la transition énergétique pour la croissance verte). Thus, France has been striving to improve the energy and environmental performance of new buildings by preparing legislation for the promotion of ‘energy-efficient buildings’ or ‘environment-friendly buildings’ for public buildings. In addition, based on the Energy Conversion Law for Green Growth, a mid to long term energy plan(PPE) has been prepared to remodel various energy-efficient buildings and develop smart grids and storage systems. Another important issue related to the management of smart buildings is the protection of personal data. Information required for management of smart buildings managed by information and communication technology is personal data about people living in the building, and it is possible to indirectly identify individual lives through processing and analysis of these data. In France, data generated in relation to smart grid is regarded as personal data and protected by the ‘Personal Data Protection Act’(Loi no 78-17 du 6 janvier 1978 relative à 1’ informatique, aux fichiers et aux libertés). Therefore, the Personal Data Protection Committee(Commission nationale de l’informatique et des libertés, CNIL) has become the main body and is carrying out activities to protect personal data. In addition, as the ‘EU General Data Protection Regulation’(GDPR) comes into effect, the explicit consent of building users and the implementation of privacy impact assessment will be carried out in the management of smart buildings in relation to the processing of related personal data. This tendency is not just for France, but for other countries as well. Therefore, even in our case, we think that we should deeply consider and respond to the problem of building energy efficiency system of buildings and the protection of personal data, in legal regulation of smart buildings. 스마트빌딩의 개념요소로는 일반적으로 ‘정보통신기능과 자동제어 시스템을 갖춘 지능형 빌딩 시스템’, ‘스마트센서와 컨트롤 시스템을 기반으로 에너지, 조명, 방재, 수자원, HVAC(Heating, Ventilation, & Air Conditioning) 등의 제공 및 관리’ 등을 들고 있다. 그러나 최근에 스마트빌딩과 관련하여 가장 많은 논의가 이루어지고 있는 주제는 ‘빌딩의 에너지의 효율화, 새로운 재생에너지의 활용, 그리고 이산화탄소 배출량의 감축 문제 등이다. 아울러 개인정보의 보호 문제도 중요하게 제기되고 있다. 프랑스에서도 스마트빌딩은 ‘녹색성장을 위한 에너지전환법’의 주요 목표인 건축물 에너지 효율개선과 밀접한 관련을 맺고 있다. 그리하여 프랑스는 우선 공공건물을 대상으로 ‘에너지수행 우수 건물’ 또는 ‘환경수행 우수 건물’의 증진을 위한 법령을 마련하여 신축 건물의 에너지 및 환경적 성능의 개선에 힘쓰고 있다. 아울러 에너지전환법에 근거하여 중장기에너지계획(PPE)를 마련하여 각종 에너지효율관련 건물의 개조와 스마트 그리드 및 저장시스템 개발을 진행하고 있다. 스마트빌딩의 관리와 관련하여 또 하나 중요한 문제는 개인정보의 보호문제이다. 정보통신기술에 의해서 처리되는 스마트 빌딩 관리에 필요한 정보(data)는 빌딩에서 생활하고 있는 사람들에 관한 정보로서 해당 정보의 가공과 분석을 통해서 개개인의 생활을 간접적으로 식별할 수 있다는 점에서 개인정보의 범주에 속한다고 할 수 있다. 프랑스에서는 스마트 그리드와 관련하여 생성된 정보를 개인정보로 보고 이를 ‘개인정보보호법’에 의해서 보호하고 있다. 따라서 CNIL(개인정보보호위원회)가 주체가 되어서 개인정보의 보호를 위한 활동을 진행하고 있다. 또한 ‘유럽연합의 일반개인정보보호규칙’(GDPR)이 발효됨에 따라 스마트빌딩의 관리에도 관련 개인정보의 처리에 대한 빌딩 사용자들의 명시적인 동의의 요구 및 개인정보 영향평가의 수행이 이루어 질 것으로 보인다. 이러한 법제의 경향은 프랑스만의 경우는 아니며, 다른 나라의 경우에도 마찬가지이다. 따라서 우리의 경우에도 스마트빌딩을 법적으로 규율함에 있어서 빌딩의 에너지 효율화 시스템의 구축이나 정보통신기술로 인한 개인정보 보호의 문제에 대해서 깊이 있는 고민과 대응이 필요할 것으로 생각한다.

Large-scale 초음파 반응기에서의 내부 초음파 에너지 분포 분석

손영규 ( Young Gyu Son ),임명희 ( Myung Hee Lim ),김원장 ( Won Jang Kim ),김지형 ( Jee Hyeong Khim ) 한국물환경학회 2008 한국물환경학회지 Vol.24 No.1

Ultrasonic cavitational energy distributions were measured in a large-scale sonoreator. In application of 110 and 170 kHz of ultrasound, the cavitational energy was just detected near the transducer module. However 35 and 72 kHz ultrasound made good distributions from the module to the end of the sonoreactor, Especially, 72 kHz ultrasound application showed most stable and highest cavitational energy value through the whole length. In the comparison between input power and cavitational energy, linear relationships were obtained in 35 and 72 kHz and it was anticipated that these results would be used for the optimization of input power for the design of sonoreactors. And three dimensional energy distribution was depicted through the mapping of cavitaional energy. Average energy in the large-scale sonoreactor was estimated as 62.8 W, which was about 40 % of input power.

Modeling and Experimental Investigation on Performance of a Wave Energy Converter with Mechanical Power Take-Off

Tri Dung Dang,Cong Binh Phan,Kyoung Kwan AHN 한국정밀공학회 2019 International Journal of Precision Engineering and Vol.6 No.4

This paper presents an experimental investigation on the hydrodynamic performance and energy conversion efficiency of an efficient wave energy converter using a simple conceptual design. The system is based on a mechanical device power take-off (PTO) so-called a bidirectional rotary motion converter (BRMC), which can absorb wave energy by converting bidirectional motion of ocean waves into one-way rotation of an electric generator. First, a prototype system is designed, fabricated and assembled in the Research Institute of Small & Medium Shipbuilding (RIMS). The tests are carried out under different conditions, such as wave profiles, the resistive load coefficients and supplementary masses. A wave simulator is controlled to make harmonic waves with different amplitudes and frequencies. Metal plates are added and fixed on the buoy as supplementary masses. Closed-loop torque control has been applied on the Magneto-Rheological (MR) brake to simulate the induced torque of an electric generator. Moreover, the rotary angle compared to vertical direction, is adjusted to investigate the influence of surge mode and heave mode combination on the absorption energy. The output power is calculated and compared with maximum theoretical absorbed power in heave mode to evaluate the efficiency of the prototype under different conditions. Finally, at optimum condition, the efficiency of the PTO system can reach 80.4% including frictional loss, and the capture width ratio is up to 41.6%.

Enhancement of Thermo-Electric Energy Conversion Using Graphene Nano-platelets Embedded Phase Change Material

유정빈,윤재륜,송영석 한국고분자학회 2021 Macromolecular Research Vol.29 No.8

Phase change materials (PCMs) containing graphene nano-platelets (GNPs) were fabricated and utilized for efficient thermo-electric energy harvesting during the phase transition process. A system composed of two different PCMs at opposite positions can absorb or release large amounts of thermal energy while remaining in a nearly isothermal condition. Based on the Seebeck effect, the energy harvesting system generates electrical current from temperature differences. The increase in the thermal conductivity of the PCMs can create isothermal fields and enhance thermoelectric energy conversion efficiency. In this study, two different PCM composites were found to exhibit higher thermal conductivity with increasing the amount of GNPs filler. The thermal conductivity of the two composites clearly increased to 0.5858 W/mK and 0.4974 W/mK, while the heating and cooling thermo-electric conversion efficiencies were also enhanced to 55.59% and 33.33%. Furthermore, the thermo-electric energy profiles were numerically modeled using the finite element method (FEM) to compare with the experimental results.

Prediction and optimization of hydrogen yield and energy conversion efficiency in a non-catalytic filtration combustion reactor for jet A and butanol fuels

Seyed Reza Shabanian,Sanaz Edrisi,Fatemeh Vahdat Khoram 한국화학공학회 2017 Korean Journal of Chemical Engineering Vol.34 No.8

Hydrogen production is one of main subjects in fuel cells. The traditional method of synthesis gas production is based on fuel reforming using catalysts. The main problem of these methods is sensitivity and fast degradation of catalysts especially when fuels with high sulfur content are used. A new technique for hydrogen production is fuelreforming using non-catalytic filtration combustion in porous media reactors. Various experimental works have been carried out to increase hydrogen production under different operating conditions such as inlet fuel velocity and equivalence ratio. First, we investigated the ability of adaptive neuro fuzzy inference system (ANFIS) for predicting the filtration combustion characteristics. Four distinct ANFIS models were developed for estimating the hydrogen yield and energy conversion efficiency for fuels of jet A and butanol. Eight different membership functions of dsigmf, gauss2mf, gaussmf, gbellmf, pimf, psigmf, trapmf and trimf were tested for training of the ANFIS networks. The results showed that the RMSE of the best developed ANFIS models for estimating of the hydrogen yield of jet fuel, hydrogen yield of butanol, conversion efficiency of jet fuel and conversion efficiency of butanol were 1.399, 1.213, 0.508 and 2.191, respectively. Moreover the R2 values of 0.998, 0.998, 0.999 and 0.999 were obtained for predicting the above mentioned variables, respectively. In the second step, a novel algorithm based on imperialist competitive algorithm (ICA) was used for optimization of hydrogen yield and energy efficiency. The maximum value of hydrogen yield and energy efficiency was 50.46% and 67.88% for jet A and 47.27% and 96.93% for butanol, respectively. The results showed that the imperialist competitive algorithm is an efficient and powerful algorithm to optimize combustion processes.