$LiNbO_{3}$ 단결정 성장과 결정의 특성에 대한 화학양론성과 첨가물$(Mg^{2+})$의 영향

한지웅,주경,심광보,오근호,Han, Ji-Woong,Joo, Kyung,Shim, Kwang-Bo,Auh, Keun-Ho The Korea Association of Crystal Growth 1999 한국결정성장학회지 Vol.9 No.1

본 연구에서는 floating zone 법에 의해서 고융조성의 순수한 $LiNbO_{3}$와 MgO가 5 mol% 첨가된 $LiNbO_{3}$ 단결정을 육성하였다. 화학양론조성의 $LiNbO_{3}$는 순수한 $LiNbO_{3}$를 VTE(vapor transport equilibration) 법에 의해 처리하여 준비하였고 위의 세 결정을 기본으로 하여 결정의 화학양론비와 첨가물($Mg^{2+}$)에 따른 $LiNbO_{3}$의 물성변화를 조사하였다. 공융조성의 $LiNbO_{3}$에서 높은 농도의 MgO 첨가는 화학양론조성 $LiNbO_{3}$와 유사한 특성을 보였다. Curie 온도는 공융조성의 순수한 $LiNbO_{3}$의 $1145^{\circ}C$에서 $1200^{\circ}C$ 이상으로 상승되었고 가시광선 영여그이 흡수단의 위치도 단차장쪽으로 10 nm 이상 이동하였다. MgO가 첨가된 결정의 $OH^{-}$ 흡수밴드의 위치는 40 nm 정도 단파장 영역으로 크게 이동하였다. The effect of dopant and stoichiometry on the physical and optical properties of $LiNbO_{3}$ were studied. We prepared three samples, undoped, MgO doped $LiNbO_{3}$ with congruent composition and near-stoichiometric $LiNbO_{3}$. Dielectric constant and transmittance in UV/VIS/IR light range were measured. The results showed that the features for high [Li]/[Nb] were similar to those for low [Li]/[Nb] but with high [Mg].

사각 격자를 이용한 단열-다공암반내 분리 단열망 구축기법에 대한 연구

한지웅,황용수,강철형,Han, Ji-Woong,Hwang, Yong-Soo,Kang, Chul-Hyung 한국방사성폐기물학회 2006 방사성폐기물학회지 Vol.4 No.1

For the accurate safety assessment of potential radioactive waste disposal site which is located in the crystalline rock it is important to simulate the mass transportation through engineered and natural barrier system precisely, characterized by porous and fractured media respectively. In this work the methods to construct discrete fracture network for the analysis of flow and mass transport through fractured-porous medium are described. The probability density function is adopted in generating fracture properties for the realistic representation of real fractured rock. In order to investigate the intersection between a porous and a fractured medium described by a 2 dimensional rectangular and a cuboid grid respectively, an additional imaginary fracture is adopted at the face of a porous medium intersected by a fracture. In order to construct large scale flow paths an effective method to find interconnected fractures and algorithms of swift detecting connectivities between fractures or porous medium and fractures are proposed. These methods are expected to contribute to the development of numerical program for the simulation of radioactive nuclide transport through fractured-porous medium from radioactive waste disposal site.

CTLA-4 항원의 세포막 도달 기작에서 친수성 N말단 아미노산 잔기의 역할

한지웅,이혜자,김진미,최은영,정현주,임수빈,최장원,정용훈,Han, Ji-Woong,Lee, Hye-Ja,Kim, Jin-Mi,Choi, Eun-Young,Chung, Hyun-Joo,Lim, Soo-Bin,Choi, Jang-Won,Chung, Yong-Hoon 대한면역학회 2002 Immune Network Vol.2 No.2

Background: This study was aimed to differentiate two forms of CTLA-4 (CD152) in activated peripheral blood lymphocyte and clarify the mechanism how cytoplasmic form of this molecule is targeted to cell surface. Methods: For this purpose we generated 2 different anti-human CD152 peptide antibodies and 5 different N'-terminal deletion mutant CTLA4Ig fusion proteins and carried out a series of Western blot and ELISA analyses. Antipeptide antibodies made in this study were anti-CTLA4pB and anti-CTLA4pN. The former recognized a region on extracellular single V-like domain and the latter recognized N'-terminal sequence of leader domain of human CD152. Results: In Western blot, the former antibody recognized recombinant human CTLA4Ig fusion protein as an antigen. And this recognition was completely blocked by preincubating antipeptide antibody with the peptide used for the antibody generation at the peptide concentration of 200 ug/ml. These antibodies were recognized human CD152 as a cytoplasmic sequestered- and a membrane bound- forms in phytohemagglutinin (PHA)-stimulated peripheral blood lymphocyte (PBL). These two forms of CD152 were further differentiated by using anti-CTLA4pN and anti-CTLA4pB antibodies such that former recognized cytosolic form only while latter recognized both cytoplasmic- and membraneforms of this molecule. Furthermore, in a transfection expression study of 5 different N'-terminal deletion mutant CTLA4Ig, mutated proteins were secreted out from transfected cell surface only when more than 6 amino acids from N'-terminal were deleted. Conclusion: Our results implies that cytosolic form of CTLA-4 has leader sequence while membrane form of this molecule does not. And also suggested is that at least N'-terminal 6 amino acid residues of human CTLA-4 are required for regulation of targeting this molecule from cytosolic- to membrane- area of activated human peripheral blood T lymphocyte.

중간 열교환기 높이 상승에 의한 KALIMER-600 원자로 풀 과도 성능 변화 분석

한지웅(Ji-Woong Han),어재혁(Jae-Hyuk Eoh),김성오(Seong-O Kim) 대한기계학회 2010 大韓機械學會論文集B Vol.34 No.11

소듐냉각 고속로 내부기기 배치 변경에 의한 초기냉각 성능변화를 검토하기 위하여 중간열교환기의 수직배치가 다른 3개의 원자로를 대상으로 COMMIX-1AR/P 코드를 활용한 다차원 해석을 수행하였다. 원통좌표계의 중심축을 기준으로 원주방향의 1/4 부분만을 모델링하고 정상상태 및 과도상태 분석을 수행하여 IHX 수직배치 변화가 초기 냉각 특성에 미치는 영향을 분석하였고, DHX를 통한 후기 냉각 모드 개시 시점에 미치는 영향도 분석하였다. 분석 결과 IHX 수직배치 상승은 원자로 풀내부 자연순환 유량을 증가시켜 초기 냉각과정에서 노심 최고 온도의 급격한 상승을 방지할 수 있으며, 초기냉각성능을 향상시키기 위한 관성회전차의 가용설계재원의 범위도 확대시킨다. 또한 IHX 수직배치 상승은 후기냉각모드에 큰 영향을 주지 않으면서 초기냉각성능의 향상에 기여할 수 있을 것으로 사료된다. The effect of increasing the elevation of an IHX (intermediate heat exchanger) on the transient performance of the KALIMER-600 reactor pool during the early phase of a loss of normal heat sink accident was investigated. Three reactors equipped with IHXs that were elevated to different heights were designed, and the thermal-hydraulic analyses were carried out for the steady and transient state by using the COMMIX-1AR/P code. In order to analyze the effects of the elevation of an IHX between reactors, various thermal-hydraulic properties such as mass flow rate, core peak temperature, RmfQ (ratio of mass flow over Q) and initiation time of decay heat removal via DHX (decay heat exchanger) were evaluated. It was found that with an increase in the IHX elevation, the circulation flow rate increases and a steep rise in the core peak temperature under the same coastdown flow condition is prevented without a delay in the initiation of the second stage of cooling. The available coastdown flow range in the reactor could be increased by increasing the elevation of the IHX.

산소부화조건에서의 반응기구 검토

한지웅(Ji-Woong Han),이창언(Chang-Eon Lee) 한국연소학회 2003 KOSCOSYMPOSIUM논문집 Vol.- No.-

연료다단 연소기의 NOx 발생특성에 관한 실험적 연구

한지웅(Ji-Woong Han),안국영(Kook-Young Ahn),김한석(Han-seok Kim),정진도(Jin-Do Chung) 한국연소학회 2001 KOSCOSYMPOSIUM논문집 Vol.- No.-

산소부화화염의 희석방법에 따른 화염특성 변화

한지웅(Ji-Woong Han),이창언(Chang-Eon Lee) 대한기계학회 2003 대한기계학회 춘추학술대회 Vol.2003 No.11

Oxygen-enriched non-premixed flame characteristics was investigated numerically with variation of<br/> dilution methods, which are Flue gas recirculation(FGR) and fuel injection recirculation(FIR). In order to<br/> compare flamelets in various oxygen-enrichment conditions reasonably, the adiabatic flame temperature and<br/> Damkoller number was held fixed by modulating amount of diluents to fuel and oxidizer stream and by<br/> varying global strain rate of flame respectively. Also modified GRI 3.0 reaction mechanism was utilized,<br/> which was able to predict oxygen-enriched methane flame correctly. Fundamental flame characteristics such<br/> as structure, heat release rate and extinction with FGR and FIR were compared in various oxygen enrichment<br/> conditions.

배기가스재순환이 산소부화화염의 CO 및 NO 생성에 미치는 영향

한지웅(Ji-Woong Han),이창언(Chang-Eon Lee) 대한기계학회 2002 대한기계학회 춘추학술대회 Vol.2002 No.5

Two kinds of oxygen-enhanced-EGR flame have been evaluated numerically in counter diffusion flame<br/> geometry with a fixed strain rate. One is CH₄/O₂-CO₂ EGR flame and the other is CH₄/O₂-CO₂-H₂O EGR<br/> flame. Recirculated gas composition was decided on a basis of stoichiometric quantity of product from 1 mole<br/> of methane and 2 mole of oxygen. A small amount of N₂ is included in oxidizer stream, in order to consider<br/> the inevitable N₂ contamination by O₂ production process or air infiltration. Results show that the inclusion of<br/> H₂O in recirculated gas promotes the conversion reaction from CO to CO₂. Under the same flame temperature<br/> condition, the EINO of two flames can be maintained at nearly same level, but the EICO of CH₄/O₂-CO₂-H₂O<br/> EGR flame becomes much less than that of CH₄/O₂-CO₂ EGR flame. CH₄/O₂-CO₂-H₂O EGR combustion is<br/> expected to overcome the shortcomings of abrupt increment of EINO in oxygen-enhanced combustion with<br/> accomplishing higher temperature than that of CH₄/Air flame. The temperature of recirculated gas should be<br/> chosen very carefully, because NO emission is very sensitive to an increment of temperature.

펌프 회전차의 관성모멘트 제공에 의한 KALIMER-600 원자로 풀 과도 성능 분석

한지웅(Ji-Woong Han),어재혁(Jae-Hyuk Eoh),이태호(Tea-Ho Lee),김성오(Seong-O Kim) 대한기계학회 2009 大韓機械學會論文集B Vol.33 No.6

The effect of an inertia moment of a pump flywheel on the thermal-hydraulic behaviors of the KALIMER-600(Korea Advanced LIquid MEtal Reactor) reactor pool during an early-phase of a loss of normal heat sink accident was investigated. The thermal-hydraulic analyses for a steady and a transient state were made by using the COMMIX-1AR/P code. In the present analysis a quarter of the reactor geometry was modeled in a cylindrical coordinate system, which includes a quarter of a reactor core and a UIS, a half of a DHX and a pump and a full IHX. In order to evaluate the effects of an inertia moment of the pump flywheel, a coastdown flow whose flow halving time amounts to 3.69 seconds was supplied to a natural circulation flow in the reactor vessel. Thermal-hydraulic behaviors in the reactor vessel were compared to those without the flywheel equipment. The numerical results showed a good agreement with the design values in a steady state. It was found that the inertia moment contributes to an increase in the circulation flow rate during the first 40 seconds, however to a decrease of it there after. It was also found that the flow stagnant region induced by a core exit overcooling decelerated the flow rate. The appearance of the first-peak temperature was delayed by the flow coastdown during the initial stages after a reactor trip.

반공진 댐퍼 최적화를 통한 비틀림 진동 개선

한지웅(Ji-woong Han),송성영(Seong-young Song),최완(Wan Choi),신순철(Soon-cheol Shin) 한국자동차공학회 2019 한국자동차공학회 학술대회 및 전시회 Vol.2019 No.11