뉴튼- 랩슨 조류계산법의 확장을 위한 손실 보정 알고리즘

채명석 건국대학교 대학원 1994 국내석사

헤밍웨이의 상징주의 - "노인과 바다"를 중심으로 -

채명석 원광대학교 2006 국내석사

상사의 리더십 유형이 직무만족과 조직몰입에 미치는 영향에 관한 연구

채명석 광운대학교 대학원 2007 국내석사

The Purposes of this study are to find out a leadership style most suitable for business management based on the transformational leadership and transactional leadership that Bemard M. Bass proposed, to investigate the primary impact of leadership style on the subordinate's job satisfaction and job involvement to his/her supervisor, as well as the differential effect of leadership styles by moderation variables such as age, position, gender and of co-work etc. In this study, there are three hypothesis suggested in order to know effective leadership style in the organizational employee focusing the transformational leadership and transactional leadership. The established three hypothesis are as follows: First, According to the leadership style, job involvement will be different. Here, leadership styles are divided into charisma, contingent reward, individual consideration, intellectual stimulation, exceptional management. Second, According to the situational variables of organizational members recognizing leadership style will be different, Here, situational variables are divided into age, gender, educational background, rank, department and continuous service year, etc. Third, According to the leadership style, job satisfaction will be different. In order to verify these hypothesis it is chosen the method of crossbar analysis, factor analysis and regression analysis. In testing hypothesis, there are not significant relation between situational variables and leadership style. And transformational leadership styles showed significant influences on the job involvement of subordinates, while transactional leadership styles showed significant influences in the job satisfaction. In future research, there is need for considering more situational factors and specific organizations.

고분자 전해질 연료전지에서 장기 내구성 평가 및 수소 내 포함된 불순물이 성능에 미치는 영향에 관한 연구

채명석 울산대학교 대학원 2015 국내석사

에너지 고갈, 환경 문제 등이 세계적인 이슈가 되면서 화석 연료의 대안으로 수소 에너지와 이를 사용하는 연료전지의 중요성이 강조되고 있다. 수소연료전지 기술은 수소의 화학에너지를 전기에너지로 바로 전환하므로 공해물질을 거의 배출하지 않아 친환경적이며, 발전효율이 높아 (약 40% 이상) 에너지 절감효과가 매우 크다. 또한, 수소, 천연가스, 에탄올, 메탄올 등 다양한 연료를 사용할 수 있어 차세대 대체에너지 기술로서 기대를 모으고 있다. 국내에서는 스택 부품을 구성하는 소재를 대부분 국외에서 수입하여 시제품을 개발하고 있다. 따라서 원천소재인 촉매 및 담지체, 전극슬러리 기술을 우선확보, 재현성을 위한 분석기법과 평가기법 개발, MEA 성능 및 내구성 개선을 위한 변수 별 제조 기술 및 평가분석, 수소 내 포함된 불순물 회복 실험을 통한 연료전지 스택의 핵심기술을 확보하는 것이 필수적이다. 본 연구에서는 수소연료전지 촉매의 내구성에 대한 실험을 수행하였으며, 크게 두 가지 실험을 진행하였다. 첫 번째, 고분산 / 고효율 백금 합금 촉매의 내구성능 평가를 진행하였으며, anode 및 cathode용 촉매를 선별하여 제조한 MEA가 500시간 장기 운전 시 ECSA가 30% 이하로 줄어드는 것을 목표로 두고 실험을 수행하였다. 두 번째는 스택에서 수소 내 포함된 불순물에 따른 성능 감소 및 회복 경향 파악 실험을 진행하였다. 두 실험을 통해 촉매의 백금 함량을 줄임과 동시에 내구성능을 높이고, 수소연료전지에 주입되는 연료의 가격을 줄여 수소연료전지 상용화를 앞당기는 데에 기여할 것으로 기대된다. The importance of the fuel cell that uses hydrogen energy is being emphasized because of global issues such as energy depletion and environmental problems. Hydrogen fuel cell technology is an eco-friendly because it does not nearly exhaust pollutants since switch directly the chemical energy of hydrogen into electrical energy. And the energy-saving effects are very large because of the high power generation efficiency (about 40% or more). Further, it has been expected as the next generation of alternative energy technologies because it is possible to use a variety of fuels, such as hydrogen, natural gas, ethanol and methanol. In Korea, most of the stack components are imported from abroad to develop prototypes of fuel cell stack. Therefore, it is essential to ensure the core technology of the fuel cell stack. For example, there are something, such as development of the source material of catalyst, supports and electrode slurry technology, analysis and assessment techniques for reproducibility, manufacturing and evaluated techniques according to the analysis parameters for MEA performance and durability improvements, recovery experiment contained impurities in hydrogen. In this study, experiments were performed for the durability of the fuel cell catalyst. And two experiments were performed significantly. First, experiments were performed for durability test of high dispersion and efficiency platinum alloy catalyst. After selecting a catalyst for the anode and cathode, the long-term durability test was performed 500 hours using the manufactured MEA. And the experiments were performed with ECSA. It was aimed reducing to 30% or less. Second, experiments were performed for performance according to the impurity contained in the hydrogen and determine the recovery trend in stack. It is thought that we could improve the durability at the same time as reducing the platinum content of the catalyst through two experiments. And it is expected to contribute to accelerate the hydrogen fuel cell commercialization by reducing the price of the fuel to be injected into the hydrogen fuel cell.

센서 장착오차를 고려한 차량용 INS/GPS/NHC 복합항법시스템

채명석 경일대학교 일반대학원 2022 국내석사

차량의 항법정보를 위해 INS(Inertial Navigation System)를 사용할 수 있다. 그러나 INS 단독으로 사용하기에는 시간에 따른 오차 증가를 막을 수 없다. 따라서 INS의 단점을 보완하기 위해 GPS(Global Positioning System)와 결합하는 INS/GPS 복합항법시스템을 구성할 수 있다. INS와 GPS는 상호보완적인 특성을 지니고 있기 때문에 안정적인 항법 정보를 제공할 수 있다. 그러나 도로환경에서는 터널, 도심/산악지역 등 GPS 음영지역이 많이 존재한다. 이때는 측정치 갱신 없이 pure INS로 동작하기 때문에 오차가 점점 증가한다. 이 문제를 해결하기 위해 INS/GPS 복합항법시스템에서 차량의 운동특성인 NHC(Non Holonomic Constrain) 정보를 측정치로 활용하여 INS/GPS/NHC 복합항법시스템을 구성할 수 있다. 이는 추가적인 센서 없이 항법 정확도를 향상시키는 방법이다. NHC는 Slip이나 점프현상이 없는 정상적인 상황에서 동체 좌표계 상의 y축과 z축의 속도는 0이라는 정보이다. 기존에는 차량의 동체 좌표계와 IMU(Inertial Measurement Unit)의 센서 좌표계는 일치하다고 가정하고 NHC를 사용했다. 그러나 실제로는 차량에 IMU를 장착하는 과정에서 동체 좌표계와 센서 좌표계는 장착 비정렬로 인해 일치하지 않게 된다. 이 경우 센서 좌표계에서는 NHC 조건이 성립하지 않게 되기 때문에 NHC 정보를 사용하게 되면 오히려 항법정보의 정확도는 떨어지게 된다. 이 문제를 해결하기 위해 IMU의 장착 비정렬을 정확하게 추정/보상 해주어야 하며, NHC 정보를 정확히 활용하기 위해 IMU의 장착 비정렬을 고려한 결합필터를 설계하여야 한다. 본 논문에서는 제안하는 결합필터는 상태변수에 y축과 z축 장착 비정렬을 추가하였으며, INS의 비선형성을 고려하여 EKF(Extended Kalman Filter)기반으로 결합필터를 설계한다. 그리고 장착 비정렬의 추정 성능 및 항법정보의 정확도를 분석하기 위해 NHC와 GPS의 측정치 사용방법에 따라 Case를 구분하여 Monte Calro 시뮬레이션 기반으로 분석한다. 그리고 차량 실험을 통해 제안하는 방법인 IMU의 장착 비정렬을 고려한 INS/GPS/NHC 복합항법시스템이 기존에 사용하던 장착 비정렬을 고려하지 않은 복합항법시스템 보다 항법결과가 우수하다는 것을 검증한다. INS (Inertial Navigation System) can be used for vehicle navigation informatio n. However, using INS alone cannot prevent an increase in error over time. Therefore, an INS/GPS integrated navigation system combined with a GPS (Global Positioning System) can be configured to make up for the shortcomings of the INS. Since INS and GPS have complementary characteristics, they can provide stable navigation information. However, in the road environment, there are many GPS shaded areas such as tunnels and urban /mountain areas. At this time, the error increases more and more because it operates with pure INS without updating the measured value. In order to solve this problem, the INS/GPS/NHC integrated navigation system can be configured by utilizing the NHC(Non Holonomic Constrain) information. This is a way to improve navigation accuracy without additional sensors. NHC is information that the velocity of the y-axis and z-axis on the fuselage coordinate system is zero in a normal situation without slip or jump phenomenon. In the past, NHC was used on the assumption that the body coordinate system of the vehicle and the sensor coordinate system of the IMU(Inertial Measurement Unit) match. However, in reality, in the process of mounting the IMU on the vehicle, the fuselage coordinate system and the sensor coordinate system do not match due to the mounting misalignment. In this case, since the NHC condition is not satisfied in the sensor coordinate system, the accuracy of the navigation information is rather lowered when the NHC information is used. To solve this problem, IMU mounting misalignment must be accurately estimated/compensated, and a coupling filter that considers IMU mounting misalignment must be designed to accurately utilize NHC information. In this paper, the proposed coupling filter adds y-axis and z-axis mounting misalignment to the state variables, and designs an EKF(Extended Kalman Filter)-based coupling filter in consideration of the nonlinearity of INS. Then, in order to analyze the estimated performance of mounting misalignment and the accuracy of navigation information, Cases are divided according to the usage of NHC and GPS measurements and analyzed based on Monte Calro simulation. And it proves that the INS/GPS/NHC integrated navigation system that considers the mounting misalignment of the IMU, which is a method proposed through vehicle experiments, has better navigation results than the conventional integrated navigation system that does not consider the mounting misalignment.

한국 디지털방송의 외주제작에 있어 문제점 및 개선에 관한 연구 : 지상파 방송을 중심으로

채명석 成均館大學校 2002 국내석사

송전손실 재분배와 전압의존형 부하모델을 적용한 유전알고리즘 기반의 무효전력 최적배분

채명석 건국대학교 대학원 2000 국내박사

This study presents the optimal reactive power dispatch problem with consideration of the transmission loss re-distribution and the voltage dependent load models based on a modified genetic algorithm. For the economic operation of a power system, the optimal reactive power dispatch(ORPD) is one of the most important problems together with the economic load dispatch and the optimal power flow. ORPD is to minimize transmission losses and improve the voltage profile by adjusting the reactive power source, while other problems are to minimize the total fuel cost in a given system. As generally known, the severe imbalance of the reactive power which is often caused by a suddenly increasing air conditioning load can bring about the voltage security problem in a power system and result in the system collapse. In such a situation, the transmission loss of power systems is exponentially increased and most a generated real power is consumed with transmission losses. And also the variation of load voltage will affect not only active power loads but also reactive power balances which may result in ultimate imbalance of reactive power supply in power systems. Therefore, the transmission loss and the voltage dependency of electrical load should be considered elaborately to make the accuracy of ORPD study higher in practical sense. That is why, in the study, the concept of transmission loss re-distribution and voltage dependent load models are introduced to ORPD problem. The conventional reactive power and voltage control problems have been solved on the basis of mathematical techniques such as linear programming and nonlinear programming which have some disadvantages such as a certain possibility of local solution, computation divergence and the limitation of problem size, etc. Many papers have been published since Carpentier proposed the nonlinear program techniques that aim to minimize transmission losses. Recently, many efforts on the fields have focussed on the non-mathematical approaches such as evolution strategies, the intelligent algorithms in order to complement the disadvantages of the mathematical techniques. This paper purposes a new genetic algorithm based approach which can handle the reactive power and improve voltage profiles to complement the disadvantages of the conventional studies. In this study, newly designed equality constraints which can reflect the effect of transmission loss and the voltage dependency of loads is adapted. And also the proper modification of genetic operators which are specially designed to optimum within a given domain. The new equality constraints include loss re-distribution algorithms(LRDA) that can distribute the system loss to all the generator, and voltage dependent load models(VDLM) with which voltage characteristics according to the power consumption pattern of the load can be observed. The main features of the improved genetic algorithm in the study can be summarized as follows: - For the coding method of the chromosome, a floating point implementation method, was used that can give a high accuracy with specially designed genetic operator in the boundary of a large scale domain in comparison with a binary implementation method, and have a merit that can be closely coded to the real variables for the ORPD problems. - The fitness function is properly designed to aim its maximum value, thus objective function to be minimized. - The arithmetic crossover, heuristic crossover and assortive arithmetic crossover are sequentially applied, according to the size of objective function in the progress of a generation number. - In order to avoid an occurrence of a initial local optimum at the optimizing process, the modified dynamic mutation based on a uniform mutation and dynamic mutation is proposed. The performance of the proposed study has been evaluated to show the improvement of voltage profiles and the minimization of transmission losses through the various case studies with the IEEE 14-bus test system and the IEEE 30-bus test system.