• 한국추진공학회지
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• 제19권2호
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• pp.9-16
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• 2015

고체 추진제를 연료로 사용하는 DACS의 압력 및 추력을 동시에 제어하기 위한 제어기법을 제안하였다. 두 제어변수를 효과적으로 제어하기 위하여 각 변수의 물리적 특성을 고려한 연속형 루프 닫힘 구조를 적용하였고, 부정정 구조를 가진 제어명령을 효율적으로 분배하기 위하여 가중벡터를 이용한 의사 역행열 기법을 제안하였다. 아울러 높은 가속도를 안정적으로 획득하기 위하여 압력 유도기법을 종말 호밍구간에 적용함으로써 추력과 압력에 관한 명령 분배의 효용성을 입증하였다.

• 전자공학회논문지B
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• 제30B권11호
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• pp.56-65
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• 1993

This paper presents the design consideration of the MFNNs(Multilayer Feed forward Neural Networks) based on the distribution of the given teching patterns. By extracting the feature points from the given teaching patterns, the structure of a network including the netowrk size and interconnection weights of a network is initialized. This network is trained based on the modified version of the EBP(Error Back Propagation) algorithm. As a result, the proposed method has the advantage of learning speed compared to the conventional learning of the MFNNs with randomly chosen initial weights. To show the effectiveness of the suggested approach, the simulation result on the approximation of a two demensional continuous function is shown.

• 전기학회논문지
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• 제67권2호
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• pp.165-172
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• 2018

This paper presents a structure of the retail electricity market based on the local pool with LDERP(Local Distributed Energy Resource Provider) for small energy prosumers. LDERP is an operator for the proposed market, which conducts performance measurement and settlement by the distribution plan determined through contract with participants. The trading process is designed similarly to the negawatt market. In the case study, the many-sided conditions of the proposed market are comparatively analyzed with the existing prosumer programs. The results demonstrate the effectiveness of the proposed framework in determining the purpose of market operating for the benefit of participants according to the various situations.

• Transactions on Electrical and Electronic Materials
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• 제1권4호
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• pp.16-19
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• 2000

Power transistors to be used in Power Integrated Circuits(PIC) are required to have low on resistance, fast switching speed, and high breakdown voltage. The lateral IGBTs(LIGBTs)are promising power devices for high voltage PIC applications, because of its superior device characteristics. In this paper, dual cathode LIGBT(DCIGBT) for high voltage is presented. We have verified the effectiveness of high blocking voltage in the new device by using two dimensional devices simulator. We have analyzed the forward blocking characteristics , the latch up performance and turn off characteristics of the proposed structure. Specially, we have focused forward blocking of LIGBT. The forward blocking voltage of conventional LIGBT and the proposed LIGBT are 120V and 165V, respectively. . The forward blocking characteristics of the proposed LIGBT is better than that of the conventional LIGBT. This forward blocking comparison exhibits a 1.5 times improvement in the proposed LIGBT.

• The Journal of Asian Finance, Economics and Business
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• 제8권12호
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• pp.371-376
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• 2021

The article analyzes the impact of factors affecting the internal control system of chemical enterprises in Vietnam, providing more empirical evidence on factors affecting the system of internal control. Research data is collected in the form of face-to-face interviews and email interviews with managers and employees working in different positions, managers at all levels, chief accountants, and accountants of 52 chemical enterprises in Vietnam. The survey results collected 310 questionnaires. After eliminating the invalid questionnaires due to many blank cells, the authors chose to use 297 questionnaires. Quantitative research was carried out with SPSS 25 software. Research results show that Business Strategy, Organizational Structure, Organization's perception of the instability of the external environment, and Organizational culture are the factors that positively affect the internal control system of chemical enterprises. This can be explained that, for chemical enterprises, Business strategy, Organizational structure, Organization's perception of the instability of the external environment, and Good organizational culture will positively impact the internal control system of chemical enterprises. Based on the research results, the authors have proposed recommendations to enhance the effectiveness of the internal control system of chemical enterprises in Vietnam, thereby contributing to improving the performance of enterprises in the chemical Vietnamese.

• The Journal of Asian Finance, Economics and Business
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• 제7권12호
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• pp.317-328
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• 2020

The board of directors play an important role in corporate climate strategy-making and decisions but might also compromise environmental policies to minimize agency cost. This study critically investigates the relationship between the attributes of the board of directors and the degree of sustainability performance for the energy sector as discussed in the literature. Our study cumulates existing knowledge offering important characteristics for a balanced board structure to increase the board's effectiveness in adopting sustainable initiatives that could reduce the adverse impact of an energy corporation's operation on the environment. Crucial attributes of the board of directors deemed to be positively associated with the commitment to reduce carbon footprint in the environment have been identified. Based on our extensive analysis of the literature we propose a conceptual framework that measures the influence of the board of directors' attributes on corporate environmental and social sustainability performance. The proposed framework will be useful as an initial step for top management and regulators to gain a better understanding of the balanced board structure required to achieve the social and environmental sustainability performance of corporations. Further, this paper contributes to a body of knowledge about how the board of directors could play a crucial role in monitoring social and environmental threats.

• Steel and Composite Structures
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• 제52권4호
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• pp.487-499
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• 2024

The primary objective of this study is to analyze the free vibration behavior of a sandwich cylindrical shell with a defective core and wavy carbon nanotube (CNT)-enhanced face sheets, utilizing the three-dimensional theory of elasticity. The intricate equations of motion for the structure are solved semi-analytically using the generalized differential quadrature method. The shell structure consists of a damaged isotropic core and two external face sheets. The distributions of CNTs are either functionally graded (FG) or uniform across the thickness, with their mechanical properties determined through an extended rule of mixture. In this research, the conventional theory regarding the mechanical effectiveness of a matrix embedding finite-length fibers has been enhanced by introducing tube-to-tube random contact. This enhancement explicitly addresses the progressive reduction in the tubes' effective aspect ratio as the filler content increases. The study investigates the influence of a damaged matrix, CNT distribution, volume fraction, aspect ratio, and waviness on the free vibration characteristics of the sandwich cylindrical shell with wavy CNT-reinforced face sheets. Unlike two-dimensional theories such as classical and the first shear deformation plate theories, this inquiry is grounded in the three-dimensional theory of elasticity, which comprehensively accounts for transverse normal deformations.

• 조명전기설비학회논문지
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• 제25권10호
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• pp.94-101
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• 2011

The proper installation of SPD and the evaluation of the SPD protection distance are basic steps for the effective protection measures of apparatus against surges within a structure. A novel method for installing SPD on the conventional distribution board without any modification was proposed and it's effectiveness was evaluated by experiments. Also, the transient overvoltage occurred across the power line from the SPD to the load was simulated with EMTP software to see how different the protection distances affecting the magnitude of the transient overvoltage. As evaluated, the effective protection method of apparatus against surges, coordinated SPD protection system is suggested as a proper measure to protect within the apartment.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1996년도 추계학술발표회논문집(1)
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• pp.309-314
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• 1996

Feasibility study has been accomplished to evaluate the effectiveness of the in-vessel core debris cooling through lower cavity flooding using two dimensional finite difference scheme. The volume of cerium pool and decay power rate generated in corium pool were evaluated as important parameters to the temperature distribution on the reactor vessel lower head through previous works. In this study, the corium volume based on the System 80＋ core structure and time dependent decay power rate are considered for feasibility evaluation. In addition, preliminary plans for the in-vessel core debris cooling through lower cavity flooding as severe accident management strategy, i.e. flooding timing, method and capacity, are suggested based on the result of the numerical study, international tendency related to in-vessel core debris cooling through lower cavity flooding.

• Journal of Magnetics
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• 제22권2호
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• pp.315-325
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• 2017

Magnetically suspended sensitive gyroscopes (MSSGs) provide an interesting alternative for achieving precious attitude angular measurement. To effectively reduce the measurement error caused by the non-uniformity of the air-gap flux density in a MSSG, this paper proposes a novel compensation method based on measuring and modeling of the air-gap flux density. The angular velocity measurement principle and the structure of the MSSG are described, and then the characteristic of the air-gap flux density has been analyzed in detail. Next, to compensate the flux density distribution error and improve the measurement accuracy of the MSSG, a real-time compensation method based on the online measurement with hall probes is designed. The common issues caused by the non-uniformity of the air-gap flux density can be effectively resolved by the proposed method in high-precision magnetically suspended configurations. Comparative simulation results before and after compensation have verified the effectiveness and superiority of the proposed compensation method.