• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2005년도 춘계학술대회 논문집
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• pp.397-400
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• 2005

Reactor Vessel is one of the most important structural part of nuclear power plant. It is manufactured by various steel forgings such as shell, head and transition ring. Head forgings has been made by open die forging process. After steel melting and ingot making, open die forging has been carried out to get a good quality which means high soundness and homogeniety of the steel forgings by using high capacity hydraulic press. This paper introduced the open die forging process and manufacturing experience of large head forgings which cant be used for the reactor vessel of 1,000MW nuclear power plant.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2002년도 생물공학의 동향 (X)
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• pp.445-448
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• 2002

The Pseudomonas fluorescens KCTC 1767, a selected and identified as potential candidate for stereo-specific resolution of rac-ketoprofen ethyl ester, was systematically investigated in order to induce the high level expression and detailed characterization of the expressing enzyme esterase. We cloned the esterase gene from chromosomal DNA of Pseudomonas fluorescens KCTC 1767 by PCR with two synthetic primers that desinged for simple purification. The recombinant esterase from Pseudomonas fluorescens KCTC 1767 exibited a high conversion rate and enantioselectivity to the (S)-ketoprofen ethyl ester as expected. The enzyme was easily purified to homogeniety by using a metal chelating affinity chromatography as a protein with poly histidine taq, and thus obtained 0.6 mg of protein from a 100 mL culture broth in a single step. The purified enzyme was steadily stable at the pH range from 7.0 to 10. The activity was also retained to be about 70% after the preincubation at $40^{\circ}C$ but over $50^{\circ}C$ lost the activity completely. The molecular mass of the esterase was estimated to be about 43 kDa on SDS-PAGE, and an identical result was also shown in gel filteration chromatography. The specific activity was calculated 27 mM/mg-protein/min by using the rac-ketoprofen ethly ester as a substrate.

• 응용통계연구
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• 제4권1호
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• pp.1-11
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• 1991

다변량분산분석이나 판별분석 등에 있어서 검정의 대상이 되는 공분산행렬의 동일성에 대한 붓스트랩방법의 활용을 살펴보았다. 두 모집단의 공분산행렬을 $\Sigma_1, \Sigma_2^$라 하면, 가설 H : $\Sigma_1 = \Sigma_2$은 불변성의 관점에서 $\Sigma = \Sigma_1 \Sigma_2^{-1}$의 고유값들이 모두 1 이라는 것과 동등하다. 본 연구에서는 (1) $\Sigma = \Sigma_1 \Sigma_2^{-1}$의 표본고유값들에 대한 편의를 붓스트랩에 의해 정정하였으며, (2) 이들의 표본분포를 붓스트랩분포로 추정하여 검정에 활용하였으며, (3) 합동붓스트랩에 의해 바플렛의 수정우도비 검정통계량의 분포를 근사하였다.

• 분석과학
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• 제8권3호
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• pp.273-279
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• 1995

납과 카드뮴을 포함하는 여러 가지 농도의 동결건조된 혈액이 외부정도관리 시료로서 제조되었다. 이 시료들은 흑연료 원자흡수분광법(GFAAS)을 이용하여 성능이 파악되었다. 매트릭스 개선제로서 0.1% ammonium dihydrogen phosphate와 0.1% Triton X-100을 사용하여 섭씨 600 내지 650도의 회화온도에서 혈액에 있는 납과 카드뮴의 정량 분석을 위한 GFAAS의 최적 분석조건이 얻어졌다. 제조된 혈액의 균질도와 안정도는 최적화된 분석조건에서 연구되었다.

• 한국세라믹학회지
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• 제33권1호
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• pp.17-24
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• 1996

Pb(Mg1/3Nb2/3)O3 powder with high purity chemical homogeniety and reactivity was prepared by solvent eva-poration of common solution. The common solution was fabricated using a Pb(NO3)2 Mg(NO)3 and NB solution which was prepared by dissolving NbC in H2O2 acquous solution. In precusor powder prepared by solvent evaporation method the synthetic temperature of Pb(Mg1/3 Nb2/3)O3 phase was lowered. And the formation of homogeneous Pb(Mg1/3Nb2/3)O3 phase was enhanced but the formation of pyrochlore phase was reduced. The dielectric constant of PMN ceramics from the synthesized powder was found to increase with both sintering temperature and excess MgO and subsequent analysis of the microstructures confirmed that this was due to an increase in grain size. The grain size dependence is explained as a consequence of low-permittivity grain boundaries.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1993년도 춘계학술대회
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• pp.38-41
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• 1993

For efficient transmission and storage of digital images, the requirements of image compression is incresing. Because the medical images contain diagnostic information small distortion has been more important factor than the low rate in such images. Generally the distortion in image is the difference of pixel values. However the image is percieved by human visual systems. So it is reasonable that human visual system characteristics be used as criteria of the image compression. In this paper, the Just Noticeable Difference curve is used as criteria of determining the homogeniety of a block and acceptibility of distortions. And Block Truncation Coding using spatial masking effect of eyes is adopted to code the blocks which contain line components. And small blocks which varies slowly can be approximated to polynomial functions successfully. We proposed the hybrid block coding scheme based on the block characteristics and human visual system characteristics. Simulation to several kinds of the medical images using this method showed that medical images can be compressed 5:1 - 10:1 without noticeable distortion.

• 한국미생물·생명공학회지
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• 제21권1호
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• pp.23-29
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• 1993

토양으로부터 nucleoside oxidase 생산균주를 분리하고 Flavobacterium meningosepticum으로 동정하였다. 생산균주의 cell free extract로부터 본 효소를 정제배율 180배, 수율 18로 전기영동적으로 균일하게 정제하였으며 정제효소의 기질 특이성을 검토한 결과 nucleoside만을 산화시키는 전형적인 nucleoside oxidase이었다. Adenosine을 기질로 한 표준효소반응계에서 stoichiometry를 검토한 결과 본 효소는 lmol adenosine을 중간 생성물인 adenosice 5'-aldeh-yde로 산화 후 1 mol adenosine 5'-carboxylic acid까지 2단계로 산화시키면서 동시에 2 mol H2O2를 생성하는 새로운 type의 nucleoside oxidase로 확인되었다. 본 효소의 높은 기질 특이성과 H2O2를 생성하는 반응성은 nucleoside의 신속 간편한 효소학적정량볍 및 임상진단용 시약의 개발에 응용될 수 있음을 시사하였다.

• 한국미생물·생명공학회지
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• 제13권3호
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• pp.185-189
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• 1985

L. sporogenes의 배양여액으로부터 균체외 $\beta$-galactosidase를 ammonium sulfate fractionation, Sephadex G-200 gel filtration, DEAE-Sephadex A-50 ion exchange chromatography와 hydroxyapatite adsorption chromatography등의 4단계 정제공정을 거쳐 순수하게 정제하였다. 정제효소는 347배 정제되어 비활성이 1,585 units/mg 이었으며 수율은 39.5%였다. Sephadex G-200 gel filtration에 의한 native enzyme의 분자량은 140,000이고 SDS-PAGE 에 의해서는 분자량이 72,000 한가지로 나타났으므로 L. sporogenes의 $\beta$-galactosidase는 동일한 subunit 2개로 구성된 dimer 효소이다.

• Biomolecules & Therapeutics
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• 제2권2호
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• pp.155-160
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• 1994

Human immunodeficiency virus type 1 (HIV-1) protease is essential for the replication of the virus and it is therefore an attractive target for antiviral drugs of HIV-1. Several dipeptide isosteres containing 2-isoxazoline or $\alpha$-hydroxy ketomethylene have been synthesized and their inhibitory effects on the HIV-1 protease examined. The enzymatically active HIV-1 protease was purified to homogeniety from E. coli transformed with a recombinant plasmid (pMAL-pro) containing the entire gene encoding the protease. The purified protease had the substrate specificity with Km value of 9.8$\mu$M when an undecapeptide His-Lys-Ala-Arg-Val-Leu-(p-nitro)Phe-Glu-Ala-Nle-Ser-amide was used as a substrate, and the products from the substrate after specific cleavage by HIV-1 protease were analyzed by HPLC. The synthetic compounds containing dipeptide isosteres showed specific inhibitory effects while a dipeptide isostere containing an isoxazoline ring inhibited the HIV-1 protease competitively with Ki value of 500 $\mu$M. Even if the inhibition effects of HIV-1 protease were not very high, these novel dipeptide isosteres can be used as key structural moieties for developing specific inhibitors of HIV-1 protease.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2003년도 추계학술발표강연 및 논문개요집
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• pp.136-136
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• 2003

In fiber optic networks, system size and cost can be significantly reduced by development of optical components through planar optical waveguides. One important step to realize the compact optical devices is to develop planar optical amplifier to compensate the losses in splitter or other components. Planar amplifier provides optical gain in devices less than tens of centimeters long, as opposed to fiber amplifiers with lengths of typically tens of meters. To achieve the same amount of gain between the planar and fiber optical amplifier, much higher Er doping levels responsible for the gain than in the fiber amplifier are required due to the reduced path length. These doping must be done without the loss of homogeniety to minimize Er ion-ion interactions which reduce gain by co-operative upconversion. Sol-gel process has become a feasible method to allow the incorporation of Er ion concentrations higher than conventional glass melting methods. In this work, Er-doped $SiO_2$-A1$_2$ $O_3$ films were prepared by two different method via sol -Eel process. Tetraethylorthosilicate(TEOS)/aluminum secondary butoxide [Al (OC$_4$ $H_{9}$)$_3$], methacryloxypropylcnethoxysaane(MPTS)/aluminum secondary butofde [Al(OC$_4$ $H_{9}$)$_3$] systems were used as starting materials for hosting Er ions. Er-doped $SiO_2$-A1$_2$ $O_3$ films obtahed after heat-treating, coatings on Si substrate were characterized by X-ray din action, FT-IR, and N-IR fluorescence spectroscopy. The luminescence properties for two different processing procedure will be compared and discussed from peak intensity and life time.