• 전력전자학회논문지
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• 제13권2호
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• pp.135-144
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• 2008

일반적으로 Intelligent power module (IPM)의 상부 스위치 구동을 위한 플로팅 전원 공급 방법으로 부트스트랩 회로가 많이 사용되고 있다. 부트스트랩 회로는 구성이 간단하고 집적화가 가능하다는 장점이 있으나 몇 가지 문제점을 가지고 있다. 상부 스위치 게이트 드라이버 회로에 전원을 공급하기 위해 매 주기마다 충분한 에너지를 충전할 수 있는 시간이 요구되며, 충전된 에너지는 한정적이므로 스위치 턴 온 (turn-on)시간의 제한을 갖게 된다. 그리고 주파수가 낮아질수록 부트스트랩 커패시터 용량이 증가하여 집적화에 장애요인이 된다. 이러한 단점은 전하 펌프 회로를 사용함으로써 보완될 수 있다. 본 논문에서는 IPM의 플로팅 전원 공급 방법으로 전하 펌프 회로를 적용하여 분석하였으며, 이러한 분석을 기반으로 전하 펌프 회로의 설계 방법을 제안하였다. 분석과 제안된 설계 방법의 타당성을 검증하기 위하여 시뮬레이션과 실험을 수행하였으며, 제시된 결과는 제안된 설계 방법의 유용성을 입증하였다.

• Journal of Power Electronics
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• 제11권2호
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• pp.218-227
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• 2011

The subject of variable step size maximum power point tracking (MPPT) algorithms has been addressed in the literature. However, most of the addressed algorithms tune the variable step size according to two variables: the photovoltaic (PV) array voltage ($V_{PV}$) and the PV array current ($I_{PV}$). Therefore, both the PV array current and voltage have to be measured. Recently, maximum power point trackers that arc based on a single variable ($I_{PV}$ or $V_{PV}$) have received a great deal of attention due to their simplicity and ease of implementation, when compared to other tracking techniques. In this paper, two methods have been proposed to design a variable step size MPPT algorithm using only a single current sensor for stand-alone battery storage PV systems. These methods utilize only the relationship between the PV array measured current and the converter duty cycle (D) to automatically adapt the step change in the duty cycle to reach the maximum power point (MPP) of the PV array. Detailed analyses and flowcharts of the proposed methods are included. Moreover, a comparison has been made between the proposed methods to investigate their performance in the transient and steady states. Finally, experimental results with field programmable gate arrays (FPGAs) are presented to verify the performance of the proposed methods.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2008년도 추계종합학술대회 B
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• pp.100-103
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• 2008

본 논문에서는 AMBA 기반으로 사용될 수 있는 H.264용 Encoder Hardware 모듈(Intra Prediction, Deblocking Filter, Context-Based Adaptive Variable Length Coding, Motion Estimation)을 Integration하여 설계하였다. 설계된 모듈은 한 매크로 블록당 최대 440 cycle내에 동작한다. 제안된 Encoder 구조를 검증하기 위하여 JM 9.4부터 reference C를 개발하였으며, reference C로부터 test vector를 추출하며 설계 된 회로를 검증하였다. 제안된 회로는 최대 166MHz clock에서 동작하며, 합성결과 Charterd 0.18um 공정에 램 포함 약 180만 gate 크기이다. MPW제작시 chip size $6{\times}6mm$의 크기와 208 pin의 Pakage 형태로 제작하였다.

• 한국전기전자재료학회논문지
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• 제21권4호
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• pp.300-304
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• 2008

A novel characterization method was investigated to estimate the trap generation during the program /erase cycles in nand flash memory cell. Utilizing Fowler-Nordheim tunneling current, floating gate potential and oxide electric field, we established a quantitative model which allows the knowledge of threshold voltage (Vth) as a function of either program or erase operation time. Based on our model, the derived results proved that interface trap density (Nit) term is only included in the program operation equation, while both Nit and oxide trap density (Not) term are included in the erase operation equation. The effectiveness of our model was tested using 50 nm nand flash memory cell with floating gate type. Nit and Not were extracted through the analysis of Program/Erase speed with respect to the endurance cycle. Trap generation and cycle numbers showed the power dependency. Finally, with the measurement of the experiment concerning the variation of cell Vth with respect to program/erase cycles, we obtained the novel quantitative model which shows similar results of relationship between experimental values and extracted ones.

• Corrosion Science and Technology
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• 제7권6호
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• pp.328-331
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• 2008

Corrosion behaviour of water intake gate steel structures with different protective measures was investigated. Five material alternatives were taken for investigation, including: imported and recycled stainless steel, carbon steel with hot zinc spraying, painting and composite coatings. Results of corrosion rate for carbon steel, SUS 304, hot zinc spray coats in three water systems of Mekong river basin (saline, blackish and fresh) were also presented. Corrosion rate of carbon steel decreased with decreasing salinity in the investigated water environments. Meanwhile, these values for zinc coated steel, behaved by another way. Environmental data for these systems were filed and discussed in relation with corrosion characteristics. Method of Life Cycle Assessment (LCA) was applied in materials selection for water intake gate construction. From point of Life Cycle Cost (LCA) the following ranking was obtained: Zinc sprayed steel < Recycled stainless steel < Composite coated steel < Painting steel < SUS 304 From investigated results, hot zinc spray coating has been applied as protective measure for steel structures of water intake systems in Mekong river basin.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2005년도 추계종합학술대회
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• pp.237-240
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• 2005

본 논문에서는 AMBA 기반으로 사용될 수 있는 H.264용 CAVLC모듈의 새로운 구조와 설계를 하였다. 설계된 모듈은 Annex B.1 의 long-start code방식과 RTP 방식을 지원하며, 한 매크로 블록당 최대 420 cycle내에 동작한다. 제안된 구조를 검증하기위하여 JM 8.5부터 reference C를 개발하였으며, reference C로부터 test vector를 추출하여 개발된 회로를 검증하였다. 제안된 회로는 54MHz clock에서 동작하며, 합성결과 hynix 0.35 um TLM 공정에 14096 gate크기이다.

• 한국정보통신학회논문지
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• 제13권12호
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• pp.2647-2654
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• 2009

본 논문에서는 AMBA 기반으로 사용될 수 있는 H.264용 Encoder Hardware 모듈 (Intra Prediction, Deblocking Filter, Context-Based Adaptive Variable Length Coding, Motion Estimation)을 Integration하여 설계하였다. 설계된 모듈은 한 매크로 블록당 최대 440 cycle내에 동작한다. 제안된 인코더 구조를 검증하기 위하여 JM 9.4부터 reference C를 개발하였으며, reference C로부터 test vector를 추출하여 설계 된 회로를 검증하였다. 제안된 회로는 최대 166MHz clock에서 동작하며, 합성결과 Charterd 0.18 um 공정에 램 포함 약 173만 gate 크기이다. MPW제작시 chip size $6{\times}6mm$의 크기와 208 pin의 Package 형태로 제작 하였다.

• Journal of Power Electronics
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• 제10권4호
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• pp.342-350
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• 2010

Randomizing the switching frequency (RSF) to reduce the electromagnetic interference (EMI) of switching power converters is a well-known technique that has been previously discussed. The randomized pulse position (RPP) technique, in which the switching frequency is kept fixed while the pulse position (the delay from the starting of the switching cycle to the turn-on instant within the cycle) is randomized, has been previously addressed in the literature for the same purpose. This paper presents a double-hybrid technique (DHB) for EMI reduction in dc-dc switching regulators. The proposed technique employed both the RSF and the RPP techniques. To effectively spread the conducted-noise frequency spectrum and at the same time attain a satisfactory output voltage quality, two parameters (switching frequency and pulse position) were randomized, and a third parameter (the duty ratio) was controlled by a digital compensator. Implementation was achieved using field programmable gate array (FPGA) technology, which is increasingly being adopted in industrial electronic applications. To evaluate the contribution of the proposed DHB technique, investigations were carried out for each basic PWM, RPP, RSF, and DHB technique. Then a comparison was made of the performances achieved. The experimentally investigated features include the effect of each technique on the common-mode, differential-mode, and total conducted-noise characteristics, and their influence on the converter’s output ripple voltage.

• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 2002년도 추계학술발표논문집
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• pp.228-233
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• 2002

In this study, Life Cycle Assessment method has been carried out the Corrugated board box in considering environmental aspects by quantifying the environmental emission and assessing its environmental impact potential. The system boundary in this study is selected from cradle to gate stage(raw material acquisition, raw material production and product manufacturing) of the paper product. To evaluate the environmental impact potential, impact categories are divided into 8 categories. As a results, abiotic resource depletion of the impact categories has the largest contribution to the total impact potential as 31.02% of total, Next were continued ecotoxicity having a contribution of 27.17%. In the life cycle, environmental impacts from law material production stage were contributed largely as 80.78%.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집B
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• pp.878-884
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• 2001

IGCC(Integrated Gasification Combined Cycle) power plant are becoming more attractive because of fuel flexibility and low emission. In this study, performances are evaluated when the low caloric value syngas fuels producted in gasification process is used a gas turbine originally designed naturel gas fuel. Using GateCycle computational thermal analysis model, performances of GE 7FA gas turbine are predicted for using four types of syngas. Also, off design performance is presented for firing syngas fuel in the gas turbine.