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이종원소와 결정성을 제어한 실크 카본 펠트의 리튬-TEMPO 흐름 전지에서의 전기화학적 특성 연구
윤승욱(Seung Uk Yoon),정지인(Ji In Jung),윤영수(Young Soo Yun),진형준(Hyoung-Joon Jin) 한국고분자학회 2020 폴리머 Vol.44 No.4
Silk fiber, a precursor rich in heteroatom, was heat-treated at various temperatures from 800 to 2800℃ to prepare carbon felts that have different heteroatom contents and carbon microstructures. With the heat treatment temperatures, the heteroatom contents of the silk-derived carbon felts (SCFs) gradually decreased, their graphitic carbon structures were continuously developed, and their electrical conductivities were linearly improved. By comparing with electrochemical reactivities of SCFs as an electrode in the lithim-2,2,6,6-tetramethylpiperidine-1oxyl (Li-TEMPO) redox flow battery (Li-TEMPO RFB) system, it was found that a redox potential separation of the SCFs heat-treated at 2800℃ (SCF2800) was reduced by ~61 mV at 10 mV s<SUP>-1</SUP> compared with the SCF heat-treated at 800℃ (SCF800). In addition, in a galvanostatic charge/discharge tests at current densities from 0.1 to 2 mA g<SUP>-1</SUP>, the capacity retention of SCF2800 is ~24% higher than that of SCF800. Moreover, in an impedance resistance measurement, the charge transfer resistance of SCF2800 which occurs in an interface between electrolyte and electrodes was much lower than that of SCF800. These results provide that the electrical conductivity of electrode materials is the key on the electrochemical performances of Li-TEMPO RFBs which is much more significant than the catalytic effect of heteroatoms on the surface of electrode materials.
그래픽스 응용을 위한 다시점 텍스처 및 깊이 정보의 근접 무손실 부호화
윤승욱(Seung-Uk Yoon),호요성(Yo-Sung Ho) 대한전자공학회 2009 電子工學會論文誌-SP (Signal processing) Vol.46 No.1
본 논문에서는 복잡한 삼차원 장면을 다시점 텍스처와 깊이맵을 이용해 표현하고 이를 부호화하는 기법을 제안한다. 이를 위해 입력 다시점 데이터를 압축된 텍스처 및 깊이맵쌍 포맷으로 변환하고 제안한 코덱인 X-Codec을 통해 손실을 최소화하면서 부호화 효율을 향상시킨다. 우선 제안한 부호화 시스템은 다시점 색상과 깊이영상을 입력으로 사용하므로 기존의 기하학 기반 렌더링 기법과 달리 렌더링 속도가 장면의 복잡도가 아닌 입력 영상의 해상도에 따라 좌우된다. 또한, 영상을 블록 단위로 나누어 부호화와 복호화를 수행하기 때문에 임의 영역 접근이 용이하고, 그래픽스 프로세싱 유닛을 이용한 실시간 렌더링이 가능하다. 실험결과 제안한 방법은 다시점 데이터를 이용한 다시점 렌더링, 선택적 복호화, 깊이정보를 이용한 삼차원 장면의 조작 등 다양한 기능을 동시에 제공하므로 대용량 데이터로부터 삼차원 장면을 탐색하는 그래픽스 응용에 유용하다. This paper introduces representation and coding schemes of multiview texture and depth data for complex three-dimensional scenes. We represent input color and depth images using compressed texture and depth map pairs. The proposed X-codec encodes them further to increase compression ratio in a near-lossless way. Our system resolves two problems. First, rendering time and output visual quality depend on input image resolutions rather than scene complexity since a depth image-based rendering techniques is used. Second, the random access problem of conventional image-based rendering could be effectively solved using our image block-based compression schemes. From experimental results, the proposed approach is useful to graphics applications because it provides multiview rendering, selective decoding, and scene manipulation functionalities.
계층적 깊이영상 정보의 압축 부호화를 위한 전처리 방법
윤승욱(Seung-Uk Yoon),김성열(Sung-Yeol Kim),호요성(Yo-Sung Ho) 한국방송·미디어공학회 2004 방송공학회논문지 Vol.9 No.3
The layered depth image (LDI) is an efficient approach to represent three-dimensional objects with complex geometry for image-based rendering (IBR). LDI contains several attribute values together with multiple layers at each pixel location. In this paper, we propose an efficient preprocessing algorithm to compress depth information of LDI. Considering each depth value as a point in the two-dimensional space, we compute the minimum distance between a straight line passing through the previous two values and the current depth value. Finally, the minimum distance replaces the current attribute value. The proposed algorithm reduces the variance of the depth information; therefore, it improves the transform and coding efficiency.
첨가제가 나트륨 이온 전지용 고분자전구체 기반 하드카본 음극 표면에 형성되는 고체 전해질 내부상 특성에 미치는 영향
김하영(Hayoung Kim),윤승욱(Seung Uk Yoon),박수봉(Subong Park),진형준(Hyoung-Joon Jin) 한국고분자학회 2020 폴리머 Vol.44 No.1
Polymeric precursor-based hard carbon with a disordered turbostratic structure has a high capacity of approximately 300 mA h g<SUP>-1</SUP> as an anode material for a sodium-ion battery. However, hard carbon has a limited cycle performance owing to the formation of unstable solid electrolyte interphase (SEI). To improve the cycle performance, several studies are underway to find suitable additives. In this study, the effects of fluorocarbon carbonate (FEC) and succinic anhydride (SA) on the life characteristics of hard carbon were investigated and the reasons were examined. All additives negatively affected the cycle performance because they increase film resistance. The high film resistance in the electrolyte with FEC was due to the formation of the SEI layer with the introduction of the sodium fluoride component with a relatively high barrier energy of 3.34 eV. On the other hand, the high film resistance in the electrolyte with SA was due to the formation of a thick formed SEI layer, and the reason of the increase in film resistance of the two additives was different.
전국 일부 학교 건축물 내의 실내 공기 및 인식도 조사
손종렬(Jong-Ryeul Sohn),윤승욱(Seung-Uk Yoon),김종혁(Jong-Hyuk Kim),이용식(Yong-Sik Lee),최한영(Han-Young Choi),김영성(Young-Sung Kim),손부순(Bu-Soon Son),양원호(Won-Ho Yang),김민회(Min-Hoi Kim) 대한환경위생공학회 2005 대한환경위생공학회지 Vol.20 No.3
Recently, indoor air quality (IAQ) in workplace, residential environments and schools has been concerned of people, scientists and related the public, and has recognized the healthy effectsrelated to IAQ, specially in schools in Korea. Therefore, objectives of this study in this study were to measure and compare the perception of IAQ of selected air pollutants in Seoul from April to September 2004. Measurement place measured 2 schools of Seoul and local 9 schools (by Kyonggi Province, Chungchong-bukdo Chungchong-namdo, Chollado-bukdo, Cholla-namdo, Kyongsang-bukdo, Kyongsang-namdo, Kwangju, schoolin Pusan each 1 place). Temperature, humidity, illumination, carbon monoxide, carbon dioxide, TBC (total bacteria count), noise, PM10, TVOC(total volatile organic compounds), HCHO (formaldehyde) were measured simultaneously. Also, we performed a questionnaire survey of 250 students and 50 teachers about their awareness for the importance of IAQ in their schools. Among this article, we handled noise, carbon monoxide, carbon dioxide, TBC, TVOC, HCHO, PM 10 in our conclusion. Major results were as follows ; Carbon monoxide (CO) was lower than indoor air standard of Korea. Carbon dioxide (CO₂) appeared that 4 schools among our sample target school exceeded in normal standard. 4 schools were almost similar with normal standard. TBC appeared that 7 schools among 11 schools were higher than standard. Noise measured school's mean value passed exceeded standard. And school which passed over standard appeared to 7 schools among 11 schools. HCHO was exceeded 4 schools by standard that excess and certainly interrelation between school's establishment year and facilities of construction was detected. PM10 was exposed all schools by fitness in standard. TVOC appeared that 9 schools among 11 measurement school was exceeded health effect standard of Japan.