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.

유전자 마커를 이용한 하수오, 백수오, 이엽우피소 및 절관우피소종 판별 연구

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),김재이(Jae-I Kim),최장덕(Jang Duck Choi),장영미(Young-Mi Jang) 한국약용작물학회 2014 한국약용작물학회 학술대회논문집 Vol.2014 No.2

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-Al₂O₃ 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.

건강기능식품에서 HPLC-UVD를 이용한 자일로올리고당 시험법의 표준화 연구

이세윤,정희선,김규헌,이미영,최정호,안정선,권광일,이혜영,Se-Yun Lee,Hee-Sun Jeong,Kyu-Heon Kim,Mi-Young Lee,Jung-Ho Choi,Jeong-Sun Ahn,Kwang-Il Kwon,Hye-Young Lee 한국식품위생안전성학회 2024 한국식품위생안전성학회지 Vol.39 No.2

본 연구는 자일로올리고당의 과학적이고 체계적인 표준화된 시험법을 마련하여 다양한 제형의 제품에 적용하고자 하였다. 최적화된 시험법을 마련하기 위해 초음파 처리 시간, 산 가수분해 시간 및 농도를 검토하여 전처리 방법을 비교 평가하였으며, HPLC-UVD를 이용하여 시료 중의 자일로올리고당을 분석하였다. 분석 시 1-phenyl-3-methyl-5-pyrazoline (PMP)으로 유도체화하고, photo diode array (PDA)가 장착된 high performance liquid chromatography (HPLC) (Nanospace SI-2)를 사용하였으며, 칼럼은 Cadenza C₁₈ (4.6 × 250 mm, 3 ㎛)이었으며, 이동상은 pH를 6.0으로 맞춘 20 mM 인산완충용액과 아세토니트릴을 78:22 비율로 혼합하여 사용하였고, 0.5 mL/min 유속으로 254 nm로 하여 분석하였다. 건강기능식품 등 시험법 마련 표준절차에 관한 가이드라인에 따라 밸리데이션을 수행하고, 표준화된 시험법을 이용하여 유통 중인 건강기능식품 대상 품목에 대해 시험법 적용 여부를 확인하였다. 표준화된 시험법은 자일로올리고당을 함유한 건강기능식품 품질관리에 대한 신뢰성을 더 높일 것으로 본다. This study aimed to develop a scientifically and systematically standardized xylooligosaccharide analytical method that can be applied to products with various formulations. The analysis method was conducted using HPLC with Cadenza C₁₈ column, involving pre-column derivatization with 1-phenyl-3-methyl-5-pyrazoline (PMP) and UV detection at 254 nm. The xylooligosaccharide content was analyzed by converting xylooligosaccharide into xylose through acid hydrolysis. The pre-treated methods were compared and evaluated by varying sonication time, acid hydrolysis time, and concentration. Optimal equipment conditions were achieved with a mobile phase consisting of 20 mM potassium phosphate buffer (pH 6)-acetonitrile (78:22, v/v) through isocratic elution at a flow rate of 0.5 mL/min (254 nm). Furthermore, we validated the advanced standardized analysis method to support the suitability of the proposed analytical procedure such as specificity, linearity, detection limits (LOD), quantitative limits (LOQ), accuracy, and precision. The standardized analysis method is now in use for monitoring relevant health-functional food products available in the market. Our results have demonstrated that the standardized analysis method is expected to enhance the reliability of quality control for healthy functional foods containing xylooligosaccharide.

HPLC-UVD를 이용한 건강기능식품에서 클로로겐산과 카페인 동시분석법 최적화 및 적용성 검증

정희선,이세윤,김규헌,이미영,최정호,안정선,오재명,권광일,이혜영,Hee-Sun Jeong,Se-Yun Lee,Kyu-Heon Kim,Mi-Young Lee,Jung-Ho Choi,Jeong-Sun Ahn,Jae-Myoung Oh,Kwang-Il Kwon,Hye-Young Lee 한국식품위생안전성학회 2024 한국식품위생안전성학회지 Vol.39 No.2

본 연구는 그린커피빈추출물이 「건강기능식품의 기준 및 규격」에 추가로 등재될 경우를 대비하여 표준화된 클로로겐산 시험법을 설정하고, 카페인이 동시 분석되도록 최적화하는 연구를 진행하였다. 최적화된 시험법을 마련하기 위해 기기분석 및 전처리 조건을 비교·분석하여 클로로겐산과 카페인을 30% 메탄올 추출하여 인산용액과 인산 함유 아세토니트릴으로 액체크로마토그래프를 통해 330 nm, 280 nm에서 분석하도록 시험법을 설정하였다. 시험법 밸리데이션 결과, 직선성 정량범위 내에서 상관계수(R²) 0.999 이상의 유의수준을 보였고, 클로로겐산과 카페인 검출한계는 0.5와 0.2 ㎍/mL, 정량한계는 1.4와 0.4 ㎍/mL로 나타났다. 정밀도와 정확도 결과는 AOAC 밸리데이션 가이드라인를 통해 적합함을 확인하였고, 클로로겐산 및 카페인 동시분석법을 최종적으로 마련하였다. 또한, 시제품과 유통제품을 통해 제형별 적용성 검토하여 클로로겐산과 카페인을 동시에 정량 가능한 시험법임을 재확인하였다. 최적화된 시험법은 클로로겐산을 함유한 건강기능식품 품질관리에 대한 신뢰성을 더 높일 것으로 본다. In this study, we analyzed chlorogenic acid indicator components in preparation for the additional listing of green coffee bean extract in the Health Functional Food Code and optimized caffeine for simultaneous analysis. We extracted chlorogenic acid and caffeine using 30% methanol, phosphoric acid solution, and acetonitrile-containing phosphoric acid and analyzed them at 330 and 280 nm, respectively, using liquid chromatography. Our analysis validation results yielded a correlation coefficient (R²) revealing a significance level of at least 0.999 within the linear quantitative range. The chlorogenic acid and caffeine detection and quantification limits were 0.5 and 0.2 ㎍/mL and 1.4, and 0.4 ㎍/mL, respectively. We confirmed that the precision and accuracy results were suitable using the AOAC validation guidelines. Finally, we developed a simultaneous chlorogenic acid and caffeine analysis approach. In addition, we confirmed that our analysis approach could simultaneously quantify chlorogenic acid and caffeine by examining the applicability of each formulation through prototypes and distribution products. In conclusion, the results of this study demonstrated that the standardized analysis would expectably increase chlorogenic acidcontaining health functional food quality control reliability.

360 VR 영상의 프로젝션 포맷 및 성능 평가 방식

박성환(Park, Seong-Hwan),김규헌(Kim, Kyu-Heon) 한국방송·미디어공학회 2019 한국방송공학회 학술발표대회 논문집 Vol.2019 No.6

분산 동영상 코딩의 코딩 방식에 따른 성능 평가와 공간 계층화 코더로서의 가능성에 대한 연구

김대연(Dae-Yeon Kim),박광훈(Gwang-Hoon Park),김규헌(Kyu-Heon Kim),서덕영(Doug-Young Suh) 한국방송·미디어공학회 2007 방송공학회논문지 Vol.12 No.6

분산 동영상 코딩 (Distributed video coding)은 Slepian과 Wolf 그리고 Wyner와 Ziv의 정보 이론에 기반을 둔 새로운 동영상 압축 패러다임이다 수신측의 보조정보를 이용하는 손실 압축인 분산 동영상 코딩은 계산의 복잡도를 디코더쪽으로 옮김으로써 적은 연산량의 동영상 인코딩을 가능하게 한다. RD 성능은 기존의 인트라 프레임 코딩보다 뛰어나지만 움직임 보상 (motion-compensated) 기반 인터 프레임 코딩의 성능에는 미치지 못한다. 본 논문은 DVC의 기본 개념과 구조에 대하여 소개하고 실험을 통하여 코딩 방식에 따른 성능을 비교 분석하며 나아가 공간 계층화 코더로서의 DVC의 성능을 보인다. Distributed video coding is a new video coding paradigm based on Slepian-Wolf and Wyner-Ziv's information theory. Distributed video coding whose decoder exploits side information transfers its computational burden from encoder to decoder, so that encoding with light computational power can be realized. RD performance is superior than that of standard video coding without motion compensation process but still has a gap with that of coding with motion compensation process. This paper introduces basic theory of distributed video coding and its structure and then shows RD performances of DVCs whose coding style is different from each other and of a DVC as a spatial scalable video coder.