• Journal of Energy Engineering
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• v.4 no.3
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• pp.364-371
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• 1995

100MW급 유류 연소 드럼형 열병합발전소의 주증기온도와 드럼수위 제어를 위한 비선형 PMBC를 개발하고 그 성능을 PID 알고리즘과 비교하였다. "first principle" approach를 사용하여 개발된 프로세스 모델은 정상상태를 과도상태에서 그 정확도를 현장의 데이터와 비교 검증한 것으로 제어기 성능 평가와 설계에 적합한 정교한 것이다. PMBC와 PID 제어의 성능을 부하증가와 연료의 열량변화 등의 외란에 비교한 결과, PMBC가 PID에 비하여 속응성, 절대오차 적분차, 제어노력 등에서 월등하게 우수한 것을 확인하였다. 것을 확인하였다.

• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.857-859
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• 1992

The molten carbonate fuel cell is a new method for generating power which uses coal gasification gas and reformed liquid natural gas for fuel at very high efficiency and with minimal pollution. The purpose of this research is to investigate principle, properties and research status of internal reforming molten carbonate fuel cell.

• Journal of the Korean Society of Safety
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• v.15 no.1
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• pp.93-99
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• 2000

This paper presents a study on the assessment of electrical fire hazards by electric circuits with leakage. The hazards are evaluated with the energy supplied by earth-leakage currents which flow in the circuits simulating the actual circuit of domestic premises. Also, operating time and current of ELB are measured by an experimental approach. A common specification of ELB used in this paper has a sensitivity of 30[mA] for leakage current working on the current-balance principle. Total charges and energy of leakage currents are calculated quantitatively by a theoretical approach and compared with the results obtained from experiments.

• Proceedings of the KIPE Conference
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• 1998.07a
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• pp.438-443
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• 1998

A simple single-stage AC/DC forward converter with transformer magnetic energy feedback technique for power factor correction is proposed. The operational principle of the proposed converter is presented. The proposed converter gives the good power factor correction, low line current harmonic distortions, and tight output voltage regulation. The prototype shows high power factor with low line current harmonics.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1995.05a
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• pp.163-172
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• 1995

100 MW급 유류연소 드럼형 열병합발전소의 주증기온도 제어를 위한 비선형 process model based control (PMBC)을 개발하고 그 성능을 PID 알고리즘과 비교하였다. 비선형 PMBC에서는 프로세스의 메캐니즘을 비교적 충실히 반영하는 모델이 필요한데, 사용된 모델은 first principle approach를 사용하여 개발된 것으로 제어기 성능 평가와 설계에 적합한 정교한 것이다. 비선형 PMBC는 비선형 피드백, feedforward, decoupling을 제공하고 분산제어에 적합하면서 모델링 오차에 민감하지 않은 장점이 있다. PMBC와 PID 제어의 성능을 부하증가와 연료의 열량변화등의 외란에 비교한 결과, PMBC가 PID에 비하여 속응성, 절대오차 적분치, 제어노력등에서 월등하게 우수한 것을 확인하였다.

• Journal of Biosystems Engineering
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• v.14 no.3
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• pp.151-157
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• 1989

A mathematical model was developed to predict traction forces of rigid wheels. The modeling was based on the energy principle that the total energy delivered to a driving wheel is equal to the works done by the useful traction force and motion resistance of that wheel. The effect of the wheel slippage was also included in the modeling. Verification of the proposed model was provided by comparing the tractive coefficients predicted by the model to those obtained experimentally at the in-door soil bin tests. The model predictions were found to be a reasonable agreement with the experimental results.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.06a
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• pp.187-188
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• 2009

• Journal of Fisheries and Marine Sciences Education
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• v.27 no.5
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• pp.1303-1309
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• 2015

The behavior and flow characteristics of the floating wave energy converter were analyzed by using CFD in this study. The average significant wave height was confirmed as 0.5~2.0m from the Korean coastal sea area. This study was carried out by selecting a range of 1.0~1.6m in the wave height to simulate the operations of realistic wave energy converter system. The principle of a piston wave maker was applied in order to produce periodic wave. The behavior of the wave energy converter and the state of the wave overtopping according to the generated periodic wave were confirmed through the unsteady three-dimensional flow analysis. It was found that the wave overtopping rate according to the generated periodic wave was in range of the 11.6~30.0 kg/s.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.12 no.4
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• pp.272-279
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• 2002

The time-dependent frequency and energy of free vibration of the spagetti problem, that is the axially moving continuum with time-varying length, are investigated. Exact expressions for the natural frequency and time-varying vibration energy are derived by dealing with traveling waves. The vibration period increases with increasing length, but the free vibration energy decreases. When the string undergoes retraction, the vibration energy increases with time. The free response of the time-varying string is represented by superposing two traveling waves.

• Journal of Power Electronics
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• v.15 no.6
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• pp.1438-1445
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• 2015

A new DC-DC power converter is researched for renewable energy and battery hybrid power supplies systems in this paper. At the charging mode, a renewable energy source provides energy to charge a battery via the proposed converter. The operating principle of the proposed converter is the same as the conventional DC-DC buck converter. At the discharging mode, the battery releases its energy to the DC bus via the proposed converter. The proposed converter is a non-isolated high step-up DC-DC converter. The coupled-inductor technique is used to achieve a high step-up voltage gain by adjusting the turns ratio. Moreover, the leakage-inductor energies of the primary and secondary windings can be recycled. Thus, the conversion efficiency can be improved. Therefore, only one power converter is utilized at the charging or discharging modes. Finally, a prototype circuit is implemented to verify the performance of the proposed converter.