• The Transactions of the Korean Institute of Power Electronics
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• v.22 no.6
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• pp.527-534
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• 2017

This paper proposes a new DC link voltage controller for a single-phase power factor correction (PFC) boost converter. The load current of the PFC boost converter affects the capacitor current, whereas the load current changes the output voltage. However, previous works that compensate output current have failed to consider the relationship between load current and duty. Thus, they also fail to maintain a constant output voltage if the load fluctuates under the conditions of a non-rated input voltage. By considering the duty in the load current compensation, the proposed method improves the load transient response regardless of the input voltage. To demonstrate its effectiveness, the proposed method is compared with other control methods by conducting PSM simulations and experiments under a rapidly changing load.

• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.124-127
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• 2001

가상현실 기술을 이용한 컴퓨터 지원 교육훈련 시스템 (VR-CATS: Virtual Reality based Computer Assisted Training System) 개발에 대한 연구를 전력연구원에서는 계속 수행해 왔다. 본 논문에서는 New VR-CATS (울진 3호기 참조)중 가상현실에서의 공동 협동 훈련 시스템(Virtual Reality Collaboration Training System)의 설계에 관하여 서술한다. 공동작업은 발전소 MCR(Main Control Room)을 3D 데이터 모델링 후 가상현실화하고 MCR 내부를 Navigation 할 수 있도록 가상패널(Virtual Panel)을 개발 및 에에 대한 엔지니어링 데이터베이스환경을 작성하여 추후 정확하고 신속한 계기 정보를 얻을 수 있도록 하며 훈련생들이 시뮬레이터실로 가지 않고 MCR에서 발전소를 운전하는 것과 같은 효과를 강의실에서 얻을 수 있다. 또한 설계기준사고 중의 하나인 LOCA 사고 복구 훈련 시나리오를 통하여 실제와 동일한 복구 훈련을 하므로서 효율적이며 현장감있는 교육훈련 수행을 가능케 한다.

• Journal of Power Electronics
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• v.15 no.2
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• pp.530-543
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• 2015

Air-cooling method is adopted on the basis of the requirements for the thermal stability and convenient field use of an electrical source transmitter. The power losses of the transmitter are determined after calculating the losses of the alternating current (AC)-direct current (DC) power supply, the constant-current circuit, and the output circuit. According to the analysis of the characteristics of a heat sink with striped fins and a fan, the engineering calculation expression of the Nusselt number and the design process for air-cooled dissipation are proposed. Experimental results verify that the error between calculated and measured values of the transmitter losses is 12.2%, which meets the error design requirements of less than 25%. Steady-state average temperature rise of the heat sink of the AC-DC power supply is $22^{\circ}C$, which meets the design requirements of a temperature rise between $20^{\circ}C$ and $40^{\circ}C$. The transmitter has favorable thermal stability with 40 kW output power.

• Proceedings of the KIPE Conference
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• 2014.07a
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• pp.118-119
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• 2014

왜곡된 역기전력을 갖는 매입형 영구자석동기전동기를 정현파 전류로 제어할 경우 역기전력의 왜곡으로 인해 발생하는 토크리플은 전동기의 진동, 소음, 효율 저하의 요인이 된다. 저속운전의 경우 토크리플을 상쇄할 수 있는 고조파전류를 인가하여 전류제어에 의해 토크리플을 줄일 수 있다. 그러나 고조파 전류제어에 의한 토크리플 저감은 전류제어기의 대역폭에 의해 전류제어 특성이 좌우되므로 고조파 보상전류의 주파수가 높은 경우 적절한 보상이 되지 않는다. 본 논문에서는 전동기의 고속운전 시 고조파 전류에 해당되는 고조파 전압을 보상함으로써 역기전력에 의한 토크리플을 저감한다. 제안된 토크리플 저감 알고리즘은 시뮬레이션을 통해 검증한다.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.10
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• pp.790-793
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• 2011

In this study, the surface modification for a silicon(Si) mold using $CHF_3$ inductively coupled plasma(ICP). The conditions under that plasma was treated a input ICP power 600 W, an operating gas pressure of 10 mTorr and plasma exposure time of 30 sec. The Si mold surface became hydrophobic after plasma treatment in order to $CF_x$(X= 1,2,3) polymer. However, as the de-molding process repeated, it was investigated that the contact angle of Si surface was decreased. So, we attempted to investigate the degradation mechanism of the accurate pattern transfer with increasing the count of the de-molding process using scanning electron microscope (SEM), contact angle, and x-ray photoelectron spectroscopy (XPS) analysis of Si mold surface.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.111.2-111.2
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• 2013

고주파 전자가속기는 고출력 RF 시스템으로 구동된다. 이러한 고주파 전자가속기에서 고출력 RF 시스템은 종종 고출력 방전으로 인해 가속관에 손상을 입힐 수 있기 때문에 조심스럽게 RF conditioning을 진행 하여야 한다. 일반적으로 RF conditioning은 아주 긴 시간을 필요로 하고, RF 출력을 서서히 높여가며 진행할 필요성이 있다. 한국원자력연구원에서는 9 MeV와 6 MeV 에너지를 출력하기 위해서는 가속관으로 RF 입력을 약 5.5 MW까지 RF conditioning을 진행하여야 한다. 따라서, 본 연구에서는 Klystron 최대 출력이 약 5.5 MW로 한국원자력연구원에서 개발된 S-band (2,856 MHz) RF 전자가속관에 RF conditioning을 진행 하였다. 가속관의 진공을 약 1.0e-7을 유지하면서 반복률을 10 Hz부터 180 Hz로 증가시켰고, RF 입력 파워는 약 6 MW까지 RF conditioning을 진행 하였다. 그 결과 짧은 시간에 RF commissioning을 진행할 수 있었다.

• Smart Media Journal
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• v.10 no.3
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• pp.54-59
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• 2021

Flight data acquired through flight instrumentation equipment during aircraft development play an important role in aircraft development and performance improvement. Therefore, as the reliability of flight instruments is required, inspection systems to check the soundness of flight instruments are very important. In this paper, we analyze the existing test system for flight data instrumentation equipment and present improvements in the hardware and software aspects of the test system. Based on this, we design and implement a test system with improved performance and present test results. Test system with improved performance improves cost savings, flexible application, and maintenance compared to the existing test system. Therefore, the robustness of the instrumentation equipment can be obtained, which can be expected to improve the reliability of flight data.

• Current Optics and Photonics
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• v.6 no.4
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• pp.420-429
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• 2022

In this paper, the details and design process of an optical system for space target detection cameras are introduced. The whole system is divided into three structures. The first structure is a short-focus visible light system for rough detection in a large field of view. The field of view is 2°, the effective focal length is 1,125 mm, and the F-number is 3.83. The second structure is a telephoto visible light system for precise detection in a small field of view. The field of view is 1°, the effective focal length is 2,300 mm, and the F-number is 7.67. The third structure is an infrared light detection system. The field of view is 2°, the effective focal length is 390 mm, and the F-number is 1.3. The visible long-focus narrow field of view and visible short-focus wide field of view are switched through a turning mirror. Design results show that the modulation transfer functions of the three structures of the system are close to the diffraction limit. It can further be seen that the short-focus wide-field-of-view distortion is controlled within 0.1%, the long-focus narrow-field-of-view distortion within 0.5%, and the infrared subsystem distortion within 0.2%. The imaging effect is good and the purpose of the design is achieved.

• International Journal of Naval Architecture and Ocean Engineering
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• v.13 no.1
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• pp.65-74
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• 2021

A key factor that governs the wave interferences of a submerged body is the dimensionless Froude number. Computational Fluid Dynamics (CFD) is used to describe the resistance force coefficients and the generated waves of two SUBOFF submarine models. Grid independence studies are performed on two cases, totally and shallowly submerged cases, with four sets of computing meshes. The highest peaks are marked by red points at given wavelengths, a line is fitted to those points with a least-squares approximation, and the half wake angle at multiple Froude numbers is defined between the fitted line and the centerline of the free surface. The results show that when the depth of the target is 1.1D, constructive interferences occur at Fn = 0.3 and 0.5, while destructive interference occurs at Fn = 0.35 with distortion of the waveform. The half wake angle is less than 19.47° because of the interference between the bow and stern wave systems.

• The Transactions of the Korean Institute of Power Electronics
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• v.27 no.1
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• pp.40-47
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• 2022

At present, the low-voltage, high-current type power supply is mainly used for effective sterilization in the ballast water treatment system. Research on PSFB converters without output capacitors has been ongoing. Such converters effectively treat ballast water without a separate disinfectant through electric pulses by applying a pulse-type power to the output electrode without an output capacitor. However, in the case of the pulse-type electrolysis treatment method, voltage overshoot can occur due to abrupt voltage fluctuations when the load changes, resulting in circuit reliability problems because of the output capacitorless system. Therefore, a new voltage control algorithm is required. In this paper, we will discuss voltage control for pulsed electrolysis topology without an output capacitor. The proposed voltage control method has been verified using Simulation and experiment. The usefulness of the proposed control method has been proven by the experimental results.