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일축배향 기공채널과 향상된 압축강도를 갖는 다공질 알루미나/뮬라이트 층상 복합체
김규헌,김태림,김동현,윤석영,박홍채,Kim, Kyu Heon,Kim, Tae Rim,Kim, Dong Hyun,Yoon, Seog Young,Park, Hong Chae 한국세라믹학회 2014 한국세라믹학회지 Vol.51 No.1
Three-layer porous alumina-mullite composites with a symmetric gradient porosity are prepared using a controlled freeze/gel-casting method. In this work, tertiary-butyl alcohol (TBA) and coal fly ash with an appropriate addition of $Al_2O_3$ were used as the freezing vehicle and the starting material, respectively. When sintered at $1300-1500^{\circ}C$, unidirectional macro-pore channels aligned regularly along the growth direction of solid TBA were developed. Simultaneously, the pore channels were surrounded by less porous structured walls. A high degree of solid loading resulted in low porosity and a small pore size, leading to higher compressive strength. The sintered porous layered composite exhibited improved compressive strength with a slight decrease in its porosity. After sintering at $1500^{\circ}C$, the layered composite consisting of outer layers with a 50 wt% solid loading showed the highest compressive strength ($90.8{\pm}3.7MPa$) with porosity of approximately 26.4%.
동결주조 다공질 뮬라이트 세라믹스의 제조와 석탄회의 재활용
김규헌,윤석영,박홍채,Kim, Kyu Heon,Yoon, Seog Young,Park, Hong Chae 한국재료학회 2016 한국재료학회지 Vol.26 No.2
In order to fabricate porous mullite ceramics with controlled pore structure and improved mechanical strength, a freeze casting route has been processed using camphene mixed with tertiary-butyl alcohol (TBA) and coal fly ash/alumina as the solvent and the ceramic material, respectively. After sintering, the solidification characteristics of camphene and TBA solvent were evident in the pore morphology, i.e., dendritic and straight pore channels formed along the solidification directions of camphene and TBA ice, respectively, after sublimation. Also, the presence of microcracks was observed in the bodies sintered at $1500^{\circ}C$, mainly due to the difference in solidification volume change between camphene and TBA. The compressive strength of the sintered bodies was found generally to be dependent, in an inverse manner, on the porosity, which was mainly determined by the processing conditions. After sintering at $1300{\sim}1500^{\circ}C$ with 30~50 wt% solid loading, the resulting mullite ceramics showed porosity and compressive strength values in ranges of 83.8~43.1% and 3.7~206.8 MPa, respectively.
식물성 식품원료의 진위 판별을 위한 종 특이 프라이머의 개발
김규헌 ( Kyu Heon Kim ),김용상 ( Yong Sang Kim ),김미라 ( Mi Ra Kim ),이호연 ( Ho Yeon Lee ),정유경 ( Yoo Kyung Jung ),이재황 ( Jae Hwang Lee ),장혜숙 ( Hye Sook Chang ),박용춘 ( Yong Chjun Park ),김상엽 ( Sang Yub Kim ),최장덕 ( 한국산업식품공학회 2014 산업 식품공학 Vol.18 No.4
본 연구에서는 식품 중 식물성 식품원료의 진위 판별을 위하여 분자생물학적 기법을 이용한 판별법을 개발하였다. 종 판별을 위한 유전자로 엽록체에 존재하는 matK 유전자와 핵 내에 존재하는 ITS 유전자 부분을 대상으로 하였으며, 가공식품에의 적용을 고려하여 PCR 산물의 크기는 200 bp 내외가 되도록 종 특이 프라이머(species-specific primer)를 설계하였다. 대상종으로는 버섯류 6종(팽이버섯, 표고버섯, 양송이버섯, 영지버섯, 새송이버섯 및 느타리버섯), 견과류 3종(밤, 잣 및 호두), 과실류 1종(대추), 채소류 6종(알로에, 미나리, 부추, 오이, 고추냉이 및 겨자), 콩류 2종(녹두, 팥) 및 기타 3종(과라나, 흰민들레 및 민들레), 총 21종을 선정하였으며, 종 특이 프라이머를 이용하여 예상되는 PCR 산물의 생성 유무를 확인하였다. PCR 분석 결과, 21종의 식물성 식품원료에 대하여 각각 예상된 PCR 산물을 확인하였으며, 프라이머별로 비교종에서 비 특이적 PCR 산물(non-specific PCR product)이 생성되지 않음을 확인하였다. 본 연구에서 개발된 종 특이 프라이머는 가열 및 가공된 식품 중 21종의 식물성 식품원료의 진위 판별에 이용될 것이며, 불량식품 근절에 적극 활용될 것으로 기대된다. In this study, a detection method was developed and optimized using a molecular biological technique to distinguish 21 vegetable food raw materials. The genes for the distinction of species in the raw materials were targeted at Internal Transcribed Spacer (ITS) in nucleus and the Maturase K (matK) gene in chloroplasts. The species-specific primers were designed for PCR products around 200 bp for their application to processed products. The amplicon size for the following: Winter mushrooms, Shiitakes, Button mushrooms, Lacquer tops, King oyster mushrooms, Oyster mushrooms, Chestnuts, Pine nuts, Walnuts, Aloe, Water dropwort, Scallions, Chinese chives, Cucumbers, Horseradish, Mustard, Mung beans, Red beans, Guarana, Korean dandelions, and Dandelions were confirmed at 166 bp ~ 245 bp, respectively. Non-specific PCR products were not detected in similar species by the species-specific primers. The detection method of raw materials developed in this study would be applied to food safety management for the eradication of adulterated food distribution and protection of consumers’ rights.
AlN-Al<sub>2</sub>O<sub>3</sub> 계에서의 상압소결 질화물복합체
김영우,김규헌,김동현,윤석영,박홍채,Kim, Young Woo,Kim, Kyu Heon,Kim, Dong Hyun,Yoon, Seog Young,Park, Hong Chae 한국세라믹학회 2014 한국세라믹학회지 Vol.51 No.5
Particulate nitride composites have been fabricated by sintering the compacted powder of AlN and 5 - 64.3 mol% $Al_2O_3$, with a small addition of $Y_2O_3$ ($Y_2O_3$/AlN, 1 wt%), in 1-atm nitrogen gas at $1650-1900^{\circ}C$. The composites were characterized in terms of sintering behavior, phase relations, microstructure and thermal shock resistance. AlN, 27R AlN pseudopolytype, and alminium oxynitride (AlON, $5AlN{\cdot}9Al_2O_3$) were found to existin the sintered material. Regardless of batch composition, the AlN-$Al_2O_3$ powder compacts exhibited similar sintering behavior; however, the degree of shrinkage commonly increased with increasing $Al_2O_3$ content, consequently giving high sintered bulk density. By increasing the $Al_2O_3$ addition up to ${\geq}50 mol%$, the matrix phase in the sintered material was converted from AlN or 27R to AlON. Above $1850^{\circ}C$, a liquid phase was formed by the reaction of $Al_2O_3$ with AlN, aided by $Y_2O_3$ and mainly existed at the grain boundaries of AlON. Thermal shock resistance was superior in the sintered composite consisting of AlON with dispersed AlN or AlN matrix phase.
나노점토가 연질 폴리우레탄/점토 다공성 나노복합체의 기계적 특성에 미치는 영향
옥경민,김규헌,김경록,김동현,김춘환,박홍채,윤석영,Ok, Kyung-Min,Kim, Kyu-Heon,Kim, Kyeong-Lok,Kim, Dong-Hyun,Kim, Chun-Hwan,Park, Hong-Chae,Yoon, Seog-Young 한국재료학회 2013 한국재료학회지 Vol.23 No.7
Flexible polyurethane/clay porous nanocomposite foams were synthesized using natural and organically modified montmorillonite clays such as bentonite, closite 10A and closite 30B. The content of nanoclays was varied from 1 to 5 wt% of polyol. Dispersion of clay in Polyurethane(PU) matrix was investigated by X-ray diffraction(Cu-$K{\alpha}$ rays of wavelength $1.54{\AA}$) using an X-ray diffractometer. Also, we determined that the thermal resistance of PU foam increased with added clay, compared to that of pure PU foam. The cell size and the fraction of open cells of the precursor foam were controlled by the addition of clay to the polyurethane foam. Modified clays were found to be more efficient cell openers than the unmodified clay. In addition, the tensile strength and elongation of the polyurethane/clay porous nanocomposites were examined. Increasing clay content increased the mechanical properties of the composites, such as tensile strength, and elongation at break. However, increasing the content over 5 wt% deteriorated the properties of the composites. We found that the nanofillers(bentonite, closite 10A and closite 30B) improved the thermal stability of the nanocomposite foam. The nanocomposite foam containing 3 wt% of closite 30B exhibited the best tensile strength and thermal stability.
김응규(Eung-Kyeu Kim),김규헌(Kyu-heon Kim) 한국정보과학회 2003 한국정보과학회 학술발표논문집 Vol.30 No.1B
화상평면내 미지호흡운동에 기인한 MRI 아티팩트를 제거하기위한 후처리방법을 제안한다. 본 연구에서 호흡운동은 2차원의 선형확대축소운동으로 모델화 된다. 신체조직을 비압축성 유체모양의 물질로 가정할 때, 화상위에서의 단위체적당 푸로톤 밀도는 일정하다고 가정한다. 사용한 모델에 따르면 호흡운동은 위상 오차와 비균일표본화 및 왜곡된 진폭변조를 MR 데이터에 부여한다. 운동 파라메타가 이이 알려져 있거나 추정가능하다고 할 때, MRI 아티팩트를 제거하기 위하여 중첩법에 기초를 둔 재구성 알고리즘을 이용한다. 운동 파라메타가 미지인 경우 스펙트럼 이동법을 적용해서 호흡변동함수와 x 방향 확대계수 및 x 방향 확대중심을 추정한다. 다음으로 에너지 최소법을 이용해서 y 방향 확대계수 및 y 방향 확대중심을 추정한다. 시뮬레이션을 통해서 제안한 방법의 유효성을 확인한다.
박종환(Jong-hwan Park),김규헌(Kyu-heon Kim),이장원(Jang-won Lee),임현정(Hyun-Jeong Yim),윤국진(Kug-jin Yun),정원식(Won-sik Cheong),허남호(Namho Hur) 大韓電子工學會 2011 電子工學會論文誌-SP (Signal processing) Vol.48 No.6
현 3D 실험방송에서는 기존 시스템과의 역호환성 보장을 위해 좌 영상과 우 영상의 듀얼 스트림을 전송하는 서비스 호환(service compatible) 3D 서비스를 진행하고 있다. 이와 같은 듀얼 스트림 방식은 제한된 방송대역 19Mbps에서 좌,우 두 개의 영상을 전송함으로 화질의 제약이 따를 수 있다. 이에 본 논문에서는 상기 고정된 대역폭으로 인한 화질의 열화없이 안정적인 화질을 제공할 수 있는 NRT(Non-RealTime)기반 연동형 지상파 3D 방송 시스템을 제안하였다. 제안한 시스템은 지상파 방송대역에 국한되지 않고 비 실시간으로 좌 또는 우 영상을 미리 전송하여 저장하고 미리 저장된 콘텐츠와 실시간 방송 콘텐츠의 동기화를 통해 고화질 스테레오스코픽 영상을 구성한다. 이를 위해 본 논문에서는 실시간 방송기술과 비 실시간 방송기술을 각각 분석하고 비 실시간 연동형 고화질 3DTV시스템을 구현할 수 있는 알고리즘을 통한 실험결과를 통해 제안한 NRT기반 연동형 지상파 3D 방송 시스템을 검증하였다. A present experimental broadcasting is service compatible to delivery left view and right view of a dual stream for backward compatible with 2D device. It has a limitation of quality for a transmission of dual stream in terrestrial bandwidth 19 Mbps. This paper proposes adjunct terrestrial-3D broadcasting system which can provide a stable quality beyond a limitation of quality from fixed bandwidth. It proposes the system that composes a high quality stereoscopic video through synchronizing Real time broadcasting and Non Real Time broadcasting Regardless of the terrestrial bandwidth. So this paper tries to analyze each technique of Real-Time broadcasting and NRT broadcasting and verify this proposal through the technique of an algorithm that we can implement NRT adjunct high quality 3DTV system and the experiments.