• 한국콘텐츠학회논문지
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• 제11권4호
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• pp.414-427
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• 2011

본 연구는 컷오프 수준에 따라 활성화 셀(cell) 수와 래더(ladder) 수 등의 통계량의 변화를 살펴보고, 컷오프 수준의 변화에 따른 가치 맵이 어떻게 변화하는지를 제시하며, 주어진 조건(100명의 응답자에게 최대 5개의 중요한 속성을 선택하도록 하여 가치사슬을 만든 후 이를 이용하여 가치 맵을 그렸을 경우)하에서 정보손실을 최소화하면서 설명력이 있는 최적의 컷오프 수준 결정과 이에 따른 가치 맵을 표현하고자 한다.

• Journal of Power Electronics
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• 제17권1호
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• pp.41-55
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• 2017

This study proposes a novel zero voltage transition (ZVT) pulse width modulation (PWM) DC-DC interleaved boost converter with an active snubber cell. All the semiconductor devices in the converter turn on and off with soft switching to reduce the switching power losses and improve the overall efficiency. Through the interleaved approach, the current stresses of the main devices and the ripple of the output voltage and input current are reduced. The main switches turn on with ZVT and turn off with zero voltage switching (ZVS). The auxiliary switch turns on with zero current switching (ZCS) and turns off with ZVS. In addition, the snubber cell does not create additional current or voltage stress on the main switches and main diodes. The proposed converter can smoothly achieve soft switching characteristics even under light load conditions. The theoretical analysis and operating stages of the proposed converter are made for the D > 50% and D < 50% modes. Finally, a prototype of the proposed converter is implemented, and the experimental results are given in detail for 500 W and 50 kHz. The overall efficiency of the proposed converter reached 95.5% at nominal output power.

• 한국통신학회논문지
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• 제38C권9호
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• pp.781-786
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• 2013

Multiplexing information over parallel data channels based on RF MIMO concept is possible to achieve considerable data rates over large transmission ranges with just a single transmitting element. Visual multiplexing MIMO techniques will send independent streams of bits using the multiple elements of the light transmitter array and recording over a group of camera pixels can further enhance the data rates. The proposed system is a combination of the reliance on computer vision algorithms for tracking and OOK cell frame modulation. LED array are controlled to transmit message in the form of digital information using ON-OFF signaling with ON-OFF pulses (ON = bit 1, OFF = bit 0). A camera captures image frames of the array which are then individually processed and sequentially decoded to retrieve data. To demodulated data transmission, a motion tracking algorithm is implemented in OpenCV (Open source Computer Vision library) to classify the transmission pattern. One of the most advantages of proposed architecture is Computer Vision (CV) based image analysis techniques which can be used to spatially separate signals and remove interferences from ambient light. It will be the future challenges and opportunities for mobile communication networking research.

• 한국해양바이오학회지
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• 제7권2호
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• pp.52-57
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• 2015

The purpose of this study was to investigate a relationship between ultraviolet radiation and initial cell density (ICD) of microalgae using a floating marine photobioreactor (PBR). To examine the effect of ultraviolet (UV) radiation in sunlight on biomass productivity as a function of ICD, 0.5-L floating PBRs covered with or without UV cut-off film were placed in an outdoor rectangular tank containing 200 L of water. At the lower ICDs, 0.01 and 0.05 g/L, biomass productivities in the PBRs without UV cut-off film decreased by $278{\pm}21%$ and $222{\pm}3%$ compared with those with the film, respectively. In contrast, the presence of UV cut-off film did not have a significant effect on biomass productivities at the higher ICDs, 0.25 and 1.25 g/L. When the differences in biomass productivity made by the UV cut-off film were plotted against the sum of cell projection area per light receiving area of the PBR, the results revealed that the inhibitory effect of UV on biomass productivity can be negligible when the sum of cell projection area is equal to the light receiving area of the PBR. These results show that photoinhibition caused by UV radiation could be eliminated via operating the PBR with a proper ICD.

• KSBB Journal
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• 제6권3호
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• pp.263-270
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• 1991

The optimal cell concentration and dilution rate for maximum ethanol productivity were obtained using dynamic simulation in cell recycled continuous bioreactor. The good control performance was observed using rule-based STR (self-tuning regulator) compared to conventional STR. Rule-base contained the scheme to implement the STR in an efficient on-off way and the scheme for the controlled variable to reach the optimal value in a short time. Since a mathematical model was used to analyze and estimate the changes of the state variables and the parameters, it was possible to understand the physical meaning of the system.

• 한국정보처리학회논문지
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• 제3권2호
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• pp.305-314
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• 1996

B-ISDN망은 ATM방식으로 멀티미디어 정보를 전송하고자 할 때, 발생될 수 있는 셀의 종류로써 미디어 정보를 갖고 있는 미디어셀과 동기 정보를 갖고 있는 동기셀로 각각 분리하였다. 트래픽 입력원을 NO-OFF 발생원으로 하는 Leaky Buck에서 확률 분포 함수를 기반으로 한 미디어셀 손실식과 동기셀 손실식을 유도하였다. 멀티미디어 동기셀은 종기 정보의 무결성과 실시간 요건을 만족시키기 위해서는 지연 민감 요건과 손실 민감 요건을 모두 갖추어야 한다. 이러한 요건을 만족 시키기 위해 우선 순위 제어 기법이 필요할 트래픽 모델링 시뮬레이션을 통해 성능 평가한 걸과, 동기셀 손실 효과 를 최소화할 수 있는 공간 우선 순위 제어 기법과 동기셀 지연 효과를 최소화할 수 있는 시간 우선 순위 제어 기법을 동시에 적용하여야 하는 필요성을 제시하였다.

• 한국통신학회논문지
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• 제22권8호
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• pp.1755-1764
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• 1997

본 논문에서는 ATM 스위치의 단일버퍼를 논리적으로 분할하는 버퍼관리 메카니즘을 제안하고, 컴퓨터 시뮬레이션을 수행하여 할당된 가중치와 제안된 셀 처리 스케줄링 알고리즘(scheduling algorithm)에 대한 트래픽(CBR/VBR/ABR)의 셀 손실확률 및 셀 지연시간을 분석하였다. 제안한 스위치의 버퍼링 시스템은 입력되는 트래픽을 특성별로 분류하여 논리적으로 분할된 버퍼에 저장하고, 스위치의 출력포트로 셀을 전송하기 위하여 동적인 라운드 로빈(round-robin) 서비스를 수행한다. 또한, 버퍼에 가중치를 설정하여 트래픽의 QoS를 보장할 수 있는 4가지의 라운드 로빈 셀 서비스 스케줄링을 분석하였다. SIMSCRIPT II.5를 이용한 시뮬레이션에서 스위치로 입력되는 트래픽은 트래픽 기술자 파라메터를 이용하여 CBR/VBR/ ABR 트래픽이 혼합된 3가지 클래스 트래픽으로 모델링하였으며 VBR과 ABR트래픽은 ON/OFF 소스로, CBR트래픽은 Poisson 소스로 모델링하였다. 본 논문에서 제안하는 버퍼관리 메카니즘과 셀 서비스 알고리즘을 분석한 결과 버퍼에 할당된 가중치의 크기와 가중치를 변화시키는 VC내퍼의 종류, 그리고 적용하는 셀 처리 알고리즘 등에 따라 각 VC가 요구하는 QoS를 보상할 수 있음을 알았다.

• Journal of Power Electronics
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• 제17권2호
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• pp.561-569
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• 2017

Power converter design requires simulation accuracy. In addition to the requirement of accurate models of power semiconductor devices, this paper highlights the role of considering a very good description of the converter circuit layout for an accurate simulation of its electrical behavior. This paper considers a simple experimental circuit including one switching cell where a MOSFET transistor controls the diode under test. The turn-off transients of the diode are captured, over which the circuit wiring has a major influence. This paper investigates the necessity for accurate modeling of the experimental test circuit wiring and the MOSFET transistor. It shows that a simple wiring inductance as the circuit wiring representation is insufficient. An adequate model and identification of the model parameters are then discussed. Results are validated through experimental and simulation results.

• 한국광학회지
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• 제10권1호
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• pp.27-31
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• 1999

DuPont 社의 광폴리머를 홀로그램 기록매질로 사용하여, 반사형 LCD에 적용할수 있는 단색의 홀로그래픽 반사판을 설계 및 제작하였다. 홀로그램 동작파장을 514nm로 하여 기록함으로써, 녹색 영역에서 가장 밝은 이미지를 구현할 수 있었다. 이미지의 방행을 표면방사와 분이시킴으로써 높은 콘트라스트 미를 얻을수 있는데, 제작한 홀로그래픽 반사판을 TN-LC cell에 적용하여, 6:1의 on/off 콘트라스트 비를 얻었다.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2000년도 춘계학술대회논문집 - 한국공작기계학회
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• pp.153-158
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• 2000

This paper addresses an intelligent robot control system using an off-line programming to teach a precise assembly task of electronic components in a flexible way. The investigated task consists of three job: heat caulking test, soldering on a circuit board, and checking of soldering defects on the back cover of a camera. This study investigates the remodelling of the most complicated cell in terms of the accuracy and fault rate among the twelve cells in a camera back-cover assembly line. We have attempted to enhance back-cover assembly line. We have attempted to enhance soldering quality, to add task flexibility, to reduce failure rate, and to increase product reliability. This study modifies the cell structure, and improves the soldering condition. The developed all system implements the real-time control of assembly with vision data, and realized an easier task teaching on off-line programming.