• 한국전기전자재료학회논문지
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• 제26권6호
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• pp.441-445
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• 2013

ZnO nanowires on the a-, c- and m-plane oriented 4H-SiC substrates were grown by using a high temperature tube furnace. Ti/Au electrodes were deposited on ZnO nanowires and a-, c- and m-plane 4H-SiC substrates, respectively. The shape and density of the ZnO nanowires were investigated by field emission scanning electron microscope. It was found that the growth direction of nanowires depends strongly on growth parameters such as growth temperature and pressure. In this work, The sensitivity of nanowires formed a-, c- and m-plane oriented 4H-SiC gas sensor was measured at $300^{\circ}C$ with CO gas concentration of 80%. The nanowires grown on a-plane oriented 4H-SiC show improved sensing performance than those on c- and m-plane oriented 4H-SiC due to the increased density of nanowire on a-plane 4H-SiC.

• Biomolecules & Therapeutics
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• 제27권6호
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• pp.577-583
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• 2019

Human cytochrome P450 2C9 is a highly polymorphic enzyme that is required for drug and xenobiotic metabolism. Here, we studied eleven P450 2C9 genetic variants-including three novel variants F69S, L310V, and Q324X-that were clinically identified in Korean patients. P450 2C9 variant enzymes were expressed in Escherichia coli and their bicistronic membrane fractions were prepared The CO-binding spectra were obtained for nine enzyme variants, indicating P450 holoenzymes, but not for the M02 (L90P) variant. The M11 (Q324X) variant could not be expressed due to an early nonsense mutation. LC-MS/MS analysis was performed to measure the catalytic activities of the P450 2C9 variants, using diclofenac as a substrate. Steady-state kinetic analysis revealed that the catalytic efficiency of all nine P450 2C9 variants was lower than that of the wild type P450 2C9 enzyme. The M05 (R150L) and M06 (P279T) variants showed high $k_{cat}$ values; however, their $K_m$ values were also high. As the M01 (F69S), M03 (R124Q), M04 (R125H), M08 (I359L), M09 (I359T), and M10 (A477T) variants exhibited higher $K_m$ and lower $k_{cat}$ values than that of the wild type enzyme, their catalytic efficiency decreased by approximately 50-fold compared to the wild type enzyme. Furthermore, the novel variant M07 (L310V) showed lower $k_{cat}$ and $K_m$ values than the wild type enzyme, which resulted in its decreased (80%) catalytic efficiency. The X-ray crystal structure of P450 2C9 revealed the presence of mutations in the residues surrounding the substrate-binding cavity. Functional characterization of these genetic variants can help understand the pharmacogenetic outcomes.

• 한국미생물·생명공학회지
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• 제16권5호
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• pp.393-397
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• 1988

고도 호열성균의 Adenylate kinase가 phospho cellulose column의 adenosine-penta-phospho adenosine affinity elution으로부터 균일하게 정제되었다. 분자량은 SDS PAGE와 gel filtration으로부터 22,000의 단량체로 밝혀졌다. 효소반응의 최적온도는 8$0^{\circ}C$이였으며 정반응의 활성화 에너지는 22.4kcal/mole이었다. 본 효소는 6M guanidine-HCI에 활성을 잃지 않았으며 10$0^{\circ}C$에서 한시간에 75%의 활성을 유지하였다. AMP, ADP, ATP에 대한 Km치는 0.01mM, 0.017mM, 0.067mM이었다.

• Asian Pacific Journal of Cancer Prevention
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• 제14권9호
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• pp.5495-5501
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• 2013

Background: Alu elements are one of the most common repetitive sequences that now constitute more than 10% of the human genome and potential targets for epigenetic alterations. Correspondingly, methylation of these elements can result in a genome-wide event that may have an impact in cancer. However, studies investigating the genome-wide status of Alu methylation in cancer remain limited. Objectives: Oral squamous cell carcinoma (OSCC) presents with high incidence in South-East Asia and thus the aim of this study was to evaluate the Alu methylation status in OSCCs and explore with the possibility of using this information for diagnostic screening. We evaluated Alu methylation status in a) normal oral mucosa compared to OSCC; b) peripheral blood mononuclear cells (PBMCs) of normal controls comparing to oral cancer patients; c) among oral epithelium of normal controls, smokers and oral cancer patients. Materials and Methods: Alu methylation was detected by combined bisulfite restriction analysis (COBRA) at 2 CpG sites. The amplified products were classified into three patterns; hypermethylation ($^mC^mC$), partial methylation ($^uC^mC+^mC^uC$), and hypomethylation ($^uC^uC$). Results: The results demonstrate that the $%^mC^mC$ value is suitable for differentiating normal and cancer in oral tissues (p=0.0002), but is not significantly observe in PBMCs. In addition, a stepwise decrease in this value was observed in the oral epithelium from normal, light smoker, heavy smoker, low stage and high stage OSCC (p=0.0003). Furthermore, receiver operating characteristic (ROC) curve analyses demonstrated the potential of combined $%^mC$ or $%^mC^mC$ values as markers for oral cancer detection with sensitivity and specificity of 86.7% and 56.7%, respectively. Conclusions: Alu hypomethylation is likely to be associated with multistep oral carcinogenesis, and might be developed as a screening tool for oral cancer detection.

• 한국재료학회지
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• 제12권5호
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• pp.414-422
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• 2002

Three different multi-component white cast irons alloyed with Cr, V, Mo and W were prepared in order to study their as-cast and solidification structures. Three combinations of the alloying elements were selected so as to obtain the different types of carbides and matrix structures : 3%C-10%Cr-5%Mo-5%W(alloy No.1), 3%C-10%V-5% Mo-5%W(alloy No. 2) and 3%C-17%Cr-3% V(alloy No.3). The as-cast microstructures were investigated with optical and scanning electron microscopes. There existed two different types of carbides, $M_7C_3$ carbide with rod-like morphology and $M_6C$ carbide with fishbone-like one, and matrix in the alloy No. 1. The alloy No. 2 consisted of MC carbide with chunky and flaky type and needle-like $M_2C$ carbide, and matrix. The chunky type referred to primary MC carbide and the flaky one to eutectic MC carbide. The morphology of the alloy No. 3 represented a typical hypo-eutectic high chromium white cast iron composed of rod-like $M_7C_3$ carbide which is very sensitive to heat flow direction and matrix. To clarify the solidification sequence, each iron(50g) was remelted at 1723K in an alumina crucible using a silicon carbide resistance furnace under argon atmosphere. The molten iron was cooled at the rate of 10K/min and quenched into water at several temperatures during thermal analysis. The solidification structures of the specimen were found to consist of austenite dendrite(${\gamma}$), $ ({\gamma}+ M_7C_3)$ eutectic and $({\gamma}+ M_6C)$ eutectic in the alloy No. 1, proeutectic MC, austenite dendrite(${\gamma}$), (${\gamma}$+MC) eutectic and $({\gamma}+ M_2C)$ eutectic in the alloy No. 2, and proeutectic $M_7C_3$ and $ ({\gamma}+ M_7C_3)$ eutectic in the alloy No 3. respectively.

• 한국건축시공학회지
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• 제10권4호
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• pp.67-74
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• 2010

현재 국내 농촌에서는 농업경쟁력을 갖추기 위해서 재배시설의 현대화 및 대형화를 추진하고 있다. 이러한 노력에도 불구하고 농촌시설물 관련 안정성 및 기술력의 문제로 인해서 해마다 자연재해로 인한 농촌시설물의 훼손 및 붕괴 사고가 빈번히 발생하고 있다. 그러므로 본 연구의 목적은 위와 같은 문제들을 해결하기 위한 하나의 방법으로써 농촌시설물을 건설 및 사용하고자 하는 모든 사람들이 보다 손쉽게 농촌시설물을 건설하고 유지관리 하는데도움을 줄 수 있는 P-C-M 지원 프로토타입 시스템 개발이다. 본 연구에서는 P-C-M 지원 시스템 프로세스 모듈설계 및 지원 시스템 알고리즘을 개발하였으며, 최종적으로는 프로토타입 시스템을 개발하였다. 이를 통하여 농촌시설물 P-C-M 지원 시스템이 개발된다면 사용자와 업체들이 보다 원활한 정보 공유를 통해서 농촌시설물의 안정성 확보 및 기술력 확보에 도움을 줄 수 있을 것으로 기대된다.

• 한국잠사곤충학회지
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• 제39권2호
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• pp.106-113
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• 1997

Three indigenous mulberry species of Morus tiliaefolia Makino, Morus mongolica C. K. Shneider and Morus bombycis Koidz. were naturally crossed and their fertilities and fruit characteristics were investigated during the years of 1996 and 1997. M. tiliaefolia Makino and M. mongolica C.K. Schneider showed low fertility, but M. bombycis Koidz. was medium in fertility. The fruits of M. tiliaefolia Makino were red-purple and midium in size and high sugar content, but those of M. mongolica C.K. Schneider were light red and small but extremely high sugar content. The total acidity of fruits was 0.73, 0.50 and 0.36-0.94% in M. tiliaefolia Makino, M. mongolica C.K. Schneider and M. bombycis Koidz. respectively. Regarding ripenening stage, M. mongolica C.K. Schneider was early and M. tiliaefolia Makino was medium, while M. bombycis Koidz was early or medium.

• 한국수산과학회지
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• 제24권1호
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• pp.39-51
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• 1991

굴 양식장 수역에 있어서 식물플랑크톤에 의한 기초생산력을 파악하기 위해 한산-거제만과 가막 양만을 대상으로 1년간 $^{14}C$ 법으로써 조사하였다. 한산-거제만의 경우, 일간기초생산력은 평균 $0.52gC/m^2/day(0.22{\~}1.02gC/m^2/day)$로 여름에 비교적 높고 겨울에 낮았다. 연간기초생산력은 $189gC/m^2/yr$로 추정되었다. 엽록소 a양은 평균 $1.70mg/m^3$로서 비교적 여름에 높았다. 가막양만의 경우, 일간기초생산력은 평균 $0.91gC/m^2/day\;(0.11{\~}3.61gC/m^2/day)$로 여름에 최고치 그리고 가을에 최저치를 보였다. 연간기초생산력은 $334gC/m^2/yr$로 추정되었다. 엽록소 a 양은 평균 $2.34mg/m^3$로서 여름에 최고치를 보였으며, 겨울에도 비 교적 높았다. 두 굴 양식장의 수면적을 고려하면, 식물플랑크톤에 의해 생산되는 탄소량은 한산-거제만이 9,450ton이고 가막양만이 37,000ton이었다. 본 조사수역의 기초생산력은 봄의 생산력 증가와 함께 여름에 높은 생산력을 보였다.

• 대한수학회보
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• 제26권1호
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• pp.69-74
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• 1989

Recently one of the present authors [2] asserted that a real hypersurface of a complex space form M$^{n}$ (c), c.neq.0, is of cyclic parallel if and only if AJ=JA and he showed also a complete and connected cyclic-parallel real hypersurface of M$^{n}$ (c), is congruent to type $A_{1}$, $A_{2}$ or A according as c>0 or c<0. A real hypersurface of a complex space form M$^{n}$ (c) is said to be covariantly cyclic constant if the cyclic sum of covariant derivative of the second fundamental form is constant. The purpose of the present paper is to extend theorem 3 and 4 in [2] when the hypersurfaces are of coveriantly cyclic constant, that is a real hypersurface of a complex space form M$^{n}$ (c), c.neq.0, is of covariantly cyclic constant if an only if AJ=JA, and a complete and connected covariantly cyclic constant real hypersurface of M$^{n}$ (c) is congruent to type $A_{1}$, $A_{2}$ or a according as c>0 or c<0.

• 한국광학회지
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• 제18권5호
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• pp.333-336
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• 2007

[ $-40^{\circ}C$ ]에서 $85^{\circ}C$의 온도에서 냉각장치 없이 동작하는 1.31 um 비냉각 DFB-LD가 유기 금속 화학 증착법에 의해 성장되었다. 높은 전광변환효율을 갖는 레이저의 제작은 스트레인이 인가된 다중양자우물 구조의 최적화를 통해 가능하며, 특히 스트레인의 양, 양자 우물의 두께, 전위장벽의 두께, 양자 우물의 수, 활성층의 폭에 주로 영향을 받는다. 본 연구에서 제작된 DFB-LD는 $25^{\circ}C$와 $85^{\circ}C$에서 전광변환효율은 0.38[mW/mA]와 0.26[mW/mA], 발진개시전류는 각각 7.1[mA]와 19.8[mA]의 값을 가졌다.