• Proceedings of the KIPE Conference
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• 2011.07a
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• pp.25-26
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• 2011

In some cases of grid connected system using photovoltaic modules, high voltage step up ratio is required. In this paper, non-isolated 2-stage cascaded boost converter with coupled inductor is proposed. Due to reduce the input current ripple and size of the inductor by using coupled inductor method, this topology is suitable for MIC(Module Integrated Converter). The operational characteristic of the proposed topology is verified through the theorical analysis, simulation and experimental waveform.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.1
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• pp.371-374
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• 2011

In this paper, a software development for design of the small photovoltaic system which is used to LED lighting is presented. For optimal design of photovoltaic systems, the operating power consumption of the LED load is considered to estimate the capacity of the solar module and battery. In order to give system design engineers a high ease of use, the software tool provides a graphical user interface and monitoring function to check operation of the system prior to installation.

• Proceedings of the KIPE Conference
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• 2008.06a
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• pp.535-537
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• 2008

This paper proposes a modularized two-stage charge equalization converter for a series-connected lithium-ion battery string. In this paper, the series-connected battery sting is modularized into M modules, and each module has K cells in series. With this modularization, low voltage stress on the electronic devices can be achieved. A two-stage dc-dc converter with cell selection switches is employed. The first stage dc-dc converter steps down the high bus voltage to about 10 V. The second stage dc-dc converter integrated with selection switches equalizes the cell voltages. A prototype for 88 lithium-ion battery cells is optimally designed and implemented. Experimental results verify that the proposed equalization method has good cell balancing performance showing low voltage stress, small size, and low cost.

• Journal of the Optical Society of Korea
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• v.18 no.6
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• pp.639-645
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• 2014

In this paper, the scheme of a single module for simultaneous operation of all-optical computing circuits, namely half adder and half subtractor, are realized using semiconductor optical amplifier (SOA) based logic gates. Optical XOR gate by employing a SOA based Mach-Zehnder interferometer (MZI) configuration is used to get the sum and difference outputs. A carry signal is generated using a SOA-four wave mixing (FWM) based AND gate, whereas, the borrow is generated by employing the SOA-cross gain modulation (XGM) effect. The obtained results confirm the feasibility of our configuration by proving the good level of quality factor i.e. ~5.5, 9.95 and 12.51 for sum/difference, carry and borrow, respectively at 0 dBm of input power.

• Convergence Security Journal
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• v.5 no.3
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• pp.87-92
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• 2005

The performance of a cryptographic module is the most important thing to achieve a high performance VPN system which realizes information security by encrypting and decrypting all the communicating data packets. However the cryptographic operations require much computation power and software cryptographic systems reveal bad performance. Thus, it is strongly recommended to develop a VPN system employing hardware component. This paper introduces a case study of developing a PCI add-on card which supports several block cipher algorithms such as DES, 3DES, AES, and SEED. The performance of them was measured by embedding the card in a commercial VPN system.

• Journal of Korea Game Society
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• v.2 no.2
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• pp.46-51
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• 2002

In this study, a real-time simulation method for the phenomena, which are too complex to be simulated during real-time computer games, was proposed based on the neural network. The procedure of proposed method is to 1) obtain correlation data between input parameters and output parameters by mathematical modeling, code analyses, and so on, 2) train the neural network with the correlation data, 3) and insert the trained neural network in a game program as a simulation module. For the case that the number of the input and output parameters is too high to be analyzed, a method was proposed to omit parameters of little importance. The method was successfully applied to severe accidents of nuclear power plants, reflecting that the method was very effective in real time simulation of complex phenomena.

• Proceedings of the KIPE Conference
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• 1999.07a
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• pp.37-40
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• 1999

DSP를 이용한 Brushless DC (BLDC) 모터의 초고속 센서리스 제어 기법 및 그 결과가 제시된다. 초고속 BLDC 모터의 센서리스 제어를 위해서 주 제어기로 DSP TMS320C240이 사용되며 제어 기법으로는 Pulse Amplitude Modulation(PAM) 기법이 사용된다. RAM 제어 기법을 사용함으로서 인버터는 six-step 방식으로 구동되며 속도 제어는 인버터 DC 링크 앞 단 쵸퍼의 전압 제어에 의해 이루어진다. 회전자 위치는 역기전력 센싱 방식에 의해 추정되며 TMS320C240의 Event Manager Module에 입력되어 Commutation 위치 및 속도가 계산된다. 계산된 속도는 디지털 PI 제어 알고리즘에 의해 처리되며 제어기의 출력은 쵸퍼의 duty 비를 변화시킨다. 개발된 DSP 제어 보드 및 제어 알고리즘의 성능을 시험하기 위해 실험이 수행되었으며 전체 제어 알고리즘은 DSP TMS320C240의 어셈블리 프로그램에 의해 구현된다. 결과로 최고 속도 50000 [rpm]에서 이상적인 응답 특성을 얻을 수 있었다.

• Proceedings of the KIEE Conference
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• 1999.07f
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• pp.2712-2714
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• 1999

The small signal model for input series-output parallel connected converter system employing charge control together with input capacitor voltage feedback loop is developed. From the model developed, the effect of input capacitor voltage feedback loop to the system stability and outer loop compensator design is analyzed. Theoretical results and simulation show that input capacitor voltage feedback loop has no critical effects on the system stability, so the system can be reduced to a equivalent single module for the stability analysis and outer loop compensator design.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.163-163
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• 2010

기존 LED의 접합온도 및 열저항은 PKG 단계에서 측정 가능 하였다. PKG에서의 접합온도 측정방식과 같은 방법으로 C사의 1W High Power LED XP2 20개를 직렬 연결하여 모듈을 구성한 20W 가로등 모듈에 대하여 접합온도를 측정 하였다. 측정결과 20W 가로등 모듈의 접합온도는 약 $61^{\circ}C$로 나타났다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.11
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• pp.1720-1729
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• 2001

Wear characteristics of Nylon and acetal pinions against steel gears for different pitch line velocities was studied with a power circulating gear test rig under unlubricated condition. Specific wear rate was measured as a function of tooth number, module, tooth width and total revolution. The worn tooth surfaces were examined with a profile projector. The Nylon pinion showed lower specific wear rate than the acetal pinion. However, the Nylon pinion was fractured at high tooth loads, whereas the acetal pinion exhibited a steady wear behavior. The wear characteristics of Nylon pinion varied significantly with the Pitch line velocity. Wear occurred most severely at the tooth tip and the region immediately below the pitch line of pinion. The dominant wear mechanisms were adhesion and abrasion.