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실시간 모바일 레이트레이싱 하드웨어를 위한 소프트 쉐도우 생성 기법
권혁주(Hyuck-Joo, Kwon),홍덕기(Dukki Hong),박우찬(Woo-Chan, Park),이상훈(Sanghoon Lee) 한국컴퓨터그래픽스학회 2017 컴퓨터그래픽스학회논문지 Vol.23 No.3
본 논문에서는 실시간 모바일 레이트레이싱에서 사실적인 그림자를 생성하기 위한 새로운 그림자 생성 기법을 제시한다. 일반적으로 레이트레이싱에서는 그림자 광선을 샘플링 하여 부드러운 그림자를 생성한다. 지금까지 이런 생성 방법은 처리 해야 할 광선의 수를 증가시키기 때문에 성능 저하의 요인이 되어왔다. 제안하는 소프트 쉐도우 생성 기법과 하드웨어 구조는 선택적 그림자 생성과 삼각형 주소 캐싱을 통해 샘플링에 의한 성능 저하를 최소화시킴으로써 이런 문제를 해결하였다. 제안된 하드웨어 구조는 모바일 레이트레이싱 하드웨어에 통합 가능한 수준이며, FPGA상에서 성능 평가 되었다. 평가 결과 제안된 기법의 성능은 4, 8, 그리고 16 샘플에 대해서 이전 기법 대비 평균 40%, 50% 그리고 56% 수준으로 향상 되었으며, 우리는 제안된 하드웨어 구조를 통해 실시간으로 소프트 쉐도우를 생성할 수 있음을 확인하였다. In this paper, a novel soft shadow method is suggested to support realistic shadows in mobile ray tracing. In ray tracing, soft shadow is generally generated by sampling a shadow ray. As this sampling method increases the number of rays to be processed, it has undermined the performance. We designed the proposed soft shadow processing method and hardware architecture to overcome this problem through selective shadow generation and triangle address caching for minimizing the performance degradation caused by sampling. The proposed hardware architecture can be integrated into a mobile ray-tracing hardware and was evaluated in terms of its performance on the FPGA. Based on the results, the rendering performance about 4, 8, and 16 samples were improved, respectively, by 40%, 50%, and 56% on average compared to the previous method, and it was found that the real-time soft shadow processing is feasible with the proposed hardware architecture.
White - Light - Emitting Materials for Organic Electroluminescent Devices
김덕영(Duck Young Kim),권오관(Oh Kwan Kwon),권혁주(Hyuck Joo Kwon),김영관(Young Kwan Kim),손병청(Byoung Chung Sohn),하윤경(Yun Kyoung Ha) 한국유화학회 2001 한국응용과학기술학회지 Vol.18 No.1
N/A White emission is important for applying organic EL devices to full-color flat panel display and backlight for liquid crystal display. In order to obtain white emission, the use of a light-emitting material which shows the white emission by itself is advantageous for these applications because of its high reliability and productivity. A chelate-metal complex such as zinc bis(2-(2-hydroxyphenyl) benzothiazolate) (Zn(BTZ)_2 was known to emit white light with a broad electroluminescence. In this study, the electroluminescent characteristics of Be(BTZ)_2 and Mg(BTZ)_2, as well as Zn(BTS)_2 were investigated using organic electroluminescent devices with the structure of ITO/TPD/ Be(BTZ)_2, Mg(BTZ)_2, or Zn(BTZ)_2/Al. It was found that the device containing Be(BTZ)_2 showed the highest power efficiency.
Eicosanoic Acid Langmuir-Blodgett(LB) 박막을 이용한 분자 다이오드의 전기적 특성
구자룡 ( Ja Ryong Koo ),이호식 ( Ho Sik Lee ),권혁주 ( Hyuck Joo Kwon ),손병청 ( Byoung Chung Sohn ) 한국유화학회 2003 한국응용과학기술학회지 Vol.20 No.2
N/A Electron transfer through an Langmuir-Blodgett(LB) monolayer film sandwiched between metal electrodes. We used an eicosanoic acid material and the material was very famous as a thin film insulating material. Eicosanoic acid monolayer was deposited by Langmuir-Blodgett(LB) technique and a subphase was a CdCl_2 solution as a 2×10^4 mol/L. Also we used a bottom electrode as an Al/Al_2O_3 and a top electrode as a Al and Ti/Al. Here, the Al_2O_3 on the bottom electrode was deposited by thermal evaporation method. The Al_2O_3 layer was acted on a tunneling darrier and insulating layer in tunnel diode. It was found that the proper transfer surface pressure for film deposition was 25 mN/m and the limiting area per molecule was about 24 A^2/molecule. When the positive and negative bias applied to the molecular device, the behavior shows that a tunnel switching characteristics. This result were analyzed regarding various mechanisms.