• Journal of the Korean Physical Society
• /
• 제73권9호
• /
• pp.1247-1254
• /
• 2018

We study the uncertainty stemming from different theoretical models in the spectroscopic factors extracted from experiments. We use three theoretical approaches, the distorted wave Born approximation (DWBA), the adiabatic distorted wave approximation (ADWA) and the continuum discretized coupled-channels method (CDCC), and analyze the $^{12}C(d,p)^{13}C$, $^{14}C(d,p)^{15}C$ reactions. We find that the uncertainty associated with the adopted theoretical models is less than 20%. We also investigate the contribution from the remnant term and observe that it gives less than 10% uncertainty. We finally make an attempt to explain the discrepancy in the spectroscopic factors of $^{17}C(\frac{3}{2}^+)$ between the ones extracted from experiments and from shell model calculations by analyzing the $^{16}C(d,p)^{17}C$ reaction.

• 한국반도체및디스플레이장비학회:학술대회논문집
• /
• 한국반도체및디스플레이장비학회 2003년도 춘계학술대회 발표 논문집
• /
• pp.94-97
• /
• 2003

본 연구에서는 반도체제조에 필수적으로 사용되는 플라즈마장비의 성능을 예측.분석하여 개발 시간 및 비용의 절감과 장비의 성능을 극대화 할 수 있도록 이론적 전산모사 환경(VIP-SEPCAD)을 개발하고 있다. VIP-SEPCAD는 플라즈마의 물리.화학적 특성을 예측하는 plasma model, 중성화학종들의 반응 및 유돈 특성을 예측하는 neutral reaction-transport model, particle의 유동 특성을 예측하는 particle transport model, particle의 생성 및 성장 특성을 예측하는 particle formation-growth model, 식각 또는 증착되는 웨이퍼 표면변화를 예측하는 surface evolution model로 구성되어 있다. 현재 개발된 VIP-SEPCAD를 이용하여 산소 플라즈마의 특성과 각종 화학성분들의 분포를 예측하고 particle의 거동에 대하여 분석하였다.

• 복식문화학회:학술대회논문집
• /
• 복식문화학회 2000년도 International Costume Culture Conference
• /
• pp.59-60
• /
• 2000

• 한국초전도학회:학술대회논문집
• /
• 한국초전도학회 2007년도 High Temperature Superconductivity Vol.XVII
• /
• pp.2-2
• /
• 2007

• 한국원자력학회:학술대회논문집
• /
• 한국원자력학회 2002년도 춘계공동학술발표회요약집
• /
• pp.186-186
• /
• 2002

• 한국신재생에너지학회:학술대회논문집
• /
• 한국신재생에너지학회 2010년도 추계학술대회 초록집
• /
• pp.111.1-111.1
• /
• 2010

This paper focuses on a systematic configuration of steam reforming fuel processor, particularly designed for small and medium sized hydrogen production application. In a typical integration of the fuel processor, there exist significant temperature gradients over the entire system which has negative effect on both catalyst life-time and system performance. Also, the volumetric inefficiency should be avoided to obtain the possible compactness for the commercial purpose. In the present work, the computational analysis will be performed to gain the fundamental insight on the transport phenomena and chemical reactions in the reformer consisting of preheating, steam reforming (SR), and water gas shift (WGS) reaction beds in the flow direction. Also, the fuel processing system includes a top-fired burner providing necessary thermal energy for endothermic catalytic reactor. A fully two-dimensional numerical modeling for a integrated fuel processing system is introduced for in-depth analysis of the heat and mass transport phenomena based on surface kinetics and catalytic process. In the model, water gas shift reaction and decomposition reaction were assumed to be at equilibrium. A kinetic model was developed and then computational results were compared with the experimental data available in the literature. Finally, the case study was done by considering the key parameters, i.e. steam to carbon (S/C) ratio and temperature. The computer-aided models developed in this study can be greatly utilized for the design of advanced fast-paced compact fuel processors research.

• Korean Chemical Engineering Research
• /
• 제51권1호
• /
• pp.58-67
• /
• 2013

PBT (polybutylene terephthalate)는 저흡수율, 치수 안정성, 내마모성 등 기계적 특성이 우수하며, 전기전자 부품, 자동차 부품, 각종 정밀 부품에 사용된다. DMT (dimethyl terephthalate)와 BD (1,4-butandiol)를 사용하여 PBT의 원료단량체인 BHBT (bis-hydroxybutyle terephthalate)를 생산하는 에스테르 교환 반응 반응에 대해 연구 하였다. 촉매로는 zinc acetate가 사용되었다. 기존의 연구에서는 반응 중 생성 메탄올이 제거되는 반회분식 반응기를 통한 kinetics 연구가 이루어져 역반응이 고려되지 않음에 따른 모델의 부정확함이 있었다. 본 연구에서는 회분식 반응기를 사용하고 반응 중 DMT와 메탄올 양을 정량하여 생성되는 MHBT (methyl hydroxylbutylene terephthalate)와 BHBT를 추정할 수 있도록 하고, 이 반응들에서 역반응들을 고려할 수 있도록 하여 보다 정확한 모델을 제안하였다. 다양한 반응속도 모델을 제시하였고, 이 모델들이 예측한 값들이 실험 데이터와 잘 일치함을 보였다.

• Korean Chemical Engineering Research
• /
• 제51권1호
• /
• pp.144-150
• /
• 2013

본 연구에서는 촉매로 zinc acetate를 사용하였고 dimethyl terephthalate(DMT)와 ethylene glycol(EG)의 에스테르 교환을 통하여 polyethylene terephthalate(PET)의 단량체인 bishydroxyethyl terephthalate(BHET)를 생성하는 반응에 대하여 알아보았다. 기존의 kinetics 연구는 에스테르 교환 반응에서 생성되는 메탄올이 반응계에서 제거되는 반회분식공정을 바탕으로 하여 이때 제거된 메탄올 양을 측정하여 역반응이 무시된 반응 kinetics 모델을 구성하였다. 본 연구에서는 회분식 반응기를 통하여 DMT와 메탄올의 양을 정량하여, 역반응을 고려한 보다 정확한 kinetics 모델을 제안하였고, 제안된 모델의 예측값들이 실험값들과 잘 일치하는 것을 보였다. 또한 모델과 실험값을 분석하여 여러 공정 변수들이 에스테르 교환 반응에 미치는 영향을 조사하였다.

• Nuclear Engineering and Technology
• /
• 제47권6호
• /
• pp.700-711
• /
• 2015

Sodium-cooled fast breeder reactors use liquid sodium as a moderator and coolant to transfer heat from the reactor core. The main hazard associated with sodium is its rapid reaction with water. Sodium-water reaction (SWR) takes place when water or vapor leak into the sodium side through a crack on a heat-transfer tube in a steam generator. If the SWR continues for some time, the SWR will damage the surface of the defective area, causing it to enlarge. This self-enlargement of the crack is called "self-wastage phenomena." A stepwise numerical evaluation model of the self-wastage phenomena was devised using a computational code of multicomponent multiphase flow involving a sodium-water chemical reaction: sodiumwater reaction analysis physics of interdisciplinary multiphase flow (SERAPHIM). The temperature of gas mixture and the concentration of NaOH at the surface of the tube wall are obtained by a numerical calculation using SERAPHIM. Averaged thermophysical properties are used to assess the local wastage depth at the tube surface. By reflecting the wastage depth to the computational grid, the self-wastage phenomena are evaluated. A two-dimensional benchmark analysis of an SWAT (Sodium-Water reAction Test rig) experiment is carried out to evaluate the feasibility of the numerical model. Numerical results show that the geometry and scale of enlarged cracks show good agreement with the experimental result. Enlarged cracks appear to taper inward to a significantly smaller opening on the inside of the tube wall. The enlarged outer diameter of the crack is 4.72 mm, which shows good agreement with the experimental data (4.96 mm).

• Nuclear Engineering and Technology
• /
• 제48권2호
• /
• pp.482-494
• /
• 2016

The Feshbache-Kermane-Koonin (FKK) multi-step direct (MSD) theory of pre-equilibrium reactions has been used to compute the single-step cross-sections for some (p,${\alpha}$) reactions using the knock-on and pick-up reaction mechanisms at two incident proton energies. For the knock-on mechanism, the reaction was assumed to have taken place by the direct ejection of a preformed alpha cluster in a shell-model state of the target. But the reaction was assumed to have taken place by the pick-up of a preformed triton cluster (also bound in a shell-model state of the target core) by the incident proton for the pick-up mechanism. The Yukawa forms of potential were used for the proton-alpha (for the knock-on process) and proton-triton (for the pick-up process) interaction and several parameter sets for the proton and alpha-particle optical potentials. The calculated cross-sections for both mechanisms gave satisfactory fits to the experimental data. Furthermore, it has been shown that some combinations of the calculated distorted wave Born approximation cross-sections for the two reaction mechanisms in the FKK MSD theory are able to give better fits to the experimental data, especially in terms of range of agreement. In addition, the theory has been observed to be valid over a wider range of energy.