• 한국막학회:학술대회논문집
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• 한국막학회 1995년도 춘계 총회 및 학술발표회
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• pp.11-15
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• 1995

Polysulfone (PS) membranes were prepared by the phase inversion process using water or isopropanol as nonsolvent. The Flory-Huggins theory for a ternary system nonsolvent/solvent/polymer is applied to describe the thermodynamic equilibria of the components. The calculated ternary phase equilibria show that demixing of a PS binary solution with n-methylpyrrolidone (NMP) will be fast in a water coagulation bath and will be delayed in an isopropanol bath. The prepared membranes were characterized by SEM, gas adsorption-desorption measurement, and permeability test. The membrane, which is precipitated by fast demixing in a water bath, has nodular structures in the skin region and includes finger-like cavities in the sublayer. The membrane coagulated by isopropanol has a very dense and thick skin structure, which is formed by delayed demixing. The membrane coagulated by isopropanol showed considerably lower pore volume and surface area compared to that observed with water coagulation method. With dimethylformamide (DMF) as solvent and 2-3 wt% of water, the solution can show the liquid-liquid phase separation due to agglomation of the polymer-lean phase from the homogeneous solution. The membranes, which were coagulated near an equilibrium state, show the large (micron size) round pores in the whole membranes. The pores do not contribute the permeation characteristics.

• 한국안전학회지
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• 제12권3호
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• pp.106-113
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• 1997

The thermal characteristics of two binary mixtures by sodium azide/manganese dioxide and ferric oxide, two ternary mixtures by sodium azide/silicon dioxide/manganese dioxide and ferric oxide were studied to obtain the basic data of gas-generating agents for air bags. The thermal reaction for all mixtures started at about $420^{\circ}C$, but the temperature at which the reaction rate reached a maximum was different with the states of samples. According to reaction results, nitrogen, nitrogen oxide and nitrogen dioxide were detected by GC-MS and so many kinds of new chemicals from sodium azide and metal oxide mixtures by XRD. NMS is considered as most stable and reasonable mixture for this types of gas-generating agents.

• Advances in materials Research
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• 제1권3호
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• pp.205-219
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• 2012

Co-Re alloy development is prompted by the search for new materials for future gas turbines which can be used at temperatures considerably higher than the present day single crystal Ni-based superalloys. The Co-Re based alloys are designed to have very high melting range. Although Co-alloys are used in gas turbine applications today, the Co-Re system was never exploited for structural applications and basic knowledge on the system is lacking. The alloy development strategy therefore is based on studying alloying additions on simple model alloy compositions of ternary and quaternary base. Various strengthening possibilities have been explored and precipitation hardening through fine dispersion of MC type carbides was found to be a promising route. In the early stages of the development we are mainly dealing with polycrystalline alloys and therefore the grain boundary embrittlement needed to be addressed and boron addition was considered for improving the ductility. In this paper recent results on the effect of boron on the strength and ductility and the stability of the fine structure of the strengthening TaC precipitates are presented. In the beginning the alloy development strategy is briefly discussed.

• 한국주조공학회지
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• 제31권3호
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• pp.130-136
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• 2011

Effects of GBF (gas bubbling filtration) treatment conditions and scrap ratio on the electric conductivity of a commercial pure aluminum for diecasting were investigated using by specific gravity and electrical conductivity measurement system, hydrogen gas analyzer, XRD, and EDS. Electrical conductivities of specimen mixed Al scrap ratio until 60% from 0% were decreased with increasing the precipitates amount and size of AlFeSi ternary intermetallic compound on the grain boundary as well as amount of porosity in the grain. On the other hand, electrical conductivities was reincreased gradually in spite of scrap ratio increase from 80% to 100%. Size of AlFeSi compound formed on the grain boundary were coarsened with the increament of scrap ratios untill 80% and GBF treatment time simultaneously.

• 조명전기설비학회논문지
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• 제21권2호
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• pp.9-14
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• 2007

Plasma display panel(PDP) 의 동작전압, 밝기, 방전늦음 시간, 광 효율, 수명, 잔상 등의 방전특성은 PDP내부의 동작가스의 혼합비율에 영향을 많이 받기 때문에, 높은 비율의 Xe 가스가 첨가된 PDP의 연구가 최근에 활발히 진행되고 있다. 그러나 high Xe이 패널에 주입되더라도 방전 개시전압과 유지전압의 상승 등의 문제점 들이 발생하고 있다. 본 연구에서는 이러한 문제를 해결하기 위한 방법으로 Ne+Xe+Kr 3원 가스에서의 가스혼합비율에 따른 방전 전압과 마진, 휘도, 광 효율을 연구하였다.

• 폴리머
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• 제32권1호
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• pp.63-69
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• 2008

두 가지 서로 다른 첨가제(additive)를 사용한 셀룰로오스 블렌드들의 기계적 성질과 모폴로지를 비교하였다. 용액 블렌딩법을 통해 만든 셀룰로오스 블렌드에는 폴리(비닐 알코올) (poly(vinyl alcohol)), PVA)과 에틸렌 글리콜(ethylene glycol, EG) 등의 첨가제가 사용되었다. 고분자 매트릭스에 사용된 첨가제의 양에 따라 블렌드 필름의 물성들은 다양하게 변하였다. PVA와 EG가 각각 30 wt%와 10 wt% 포함되었을 때 셀룰로오스 블렌드 필름의 최종인장 강도와 초기 탄성률은 가장 높은 값을 보였다. 용액 블렌딩법을 이용하여 EG를 셀룰로오스 블렌드(셀룰로오스/PVA (70/30=w/w))에 섞은 삼성분계(ternary system) 필름을 얻었으며, 이 필름에서는 EG가 40 wt% 포함되었을 때 기계적 물성이 가장 높은 값을 가졌다. 또한, 이 값은 셀룰로오스를 이용한 이성분계 블렌드 필름들보다 더 높은 기계적 성질을 나타내었다. 삼성분계 블렌드 필름에서 산소 투과도($O_2TR$)는 EG 함량이 증가할수록 가스 투과도 역시 일정하게 감소하였다. 전체적으로는 블렌드된 셀룰로오스 필름의 기계적 성질이 순수한 셀룰로오스보다 더 우수하였다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2012년도 추계 학술논문 발표대회
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• pp.65-66
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• 2012

The cement used in the construction industry of the manufacturing process, large amounts of the greenhouse gas, CO₂ and is currently being studied for cement substitutes that reduce greenhouse gas issue. Therefore, the this study as a replacement for cement industrial by-product of blast furnace slag, red mud, silica fume and alkali-activator, using only inorganic composites without high-temperature calcination process were manufactured. The waste gypsum board micro powder added to compensate for the shrinkage cracks, the compressive strength and flow, and length change characteristics were investigated. Consequently, The setting time was shortened as GB added And liquidity was reduced. GB 2%, 7 days curing the added strength of specimens was the highest. Came out, and change the length of the Plain least.

• 한국세라믹학회지
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• 제37권2호
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• pp.164-167
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• 2000

Flue gases in the iron foundry consist of 15~20% CO2 as an air pollution gas whose emission should be mitigated in order to protect the environment. In the present study, ultrafine powders of NixZn1-xFe2O4 as a potential catalyst for the CO2 decomposition were prepared by the coprecipitation methods. Oxygen deficient ferrites (MeFe2O4-$\delta$) can decompose CO2 as C and O2 at a low temperature of about 30$0^{\circ}C$. The XRD result of synthesized ferrites showed the spinel structure of ferrites and ICP-AES and EDS quantitative analyses showed the composition similar with initial molar ratios of the mixed solution prior to reaction. The BET surface area of the (Ni, Zn)-ferrites was about 77~89.5$m^2$/g and their particle size was observed about 10~20 nm. The CO2 decomposition efficiency of the oxygen deficient (Nix, Zn1-x)-ferrites was the highest at x=0.3, and the ternary (Ni, Zn)-ferrites was better than that of binary Ni-ferrites.

• Nuclear Engineering and Technology
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• 제53권8호
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• pp.2488-2498
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• 2021

The wall film-wise condensation plays an important role in the heat transfer processes of heat exchangers, refrigerators, and air conditioner. In the field of nuclear engineering, steam condensation is often utilized in safety systems to remove the core decay heat under both transient and accident conditions. In particular, passive containment cooling system (PCCS), are designed to ensure containment safety under severe accident conditions. A computational fluid dynamics (CFD) scale analysis has been conducted to calculate the heat transfer rate of the PCCS. However, despite the increase in computing power, there are challenges in the long-term transient simulation of containment using CFD scale codes. In this study, a heat structure coupling between the CFD and system analysis codes was performed to efficiently analyze PCCS. In addition, the component unstructured program for interfacial dynamics (CUPID) was improved to analyze the condensation behavior of ternary gas mixtures. Thereafter, the condensation heat transfer on the primary side was calculated using the improved CUPID and CFD code, whereas that on the secondary side was simulated using MARS. Both the coupled codes were validated against the CONAN facility database. Finally, conjugate heat transfer simulations with wall condensation in the presence of non-condensable gases were appropriately performed.

• 멤브레인
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• 제22권2호
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• pp.128-134
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• 2012

본 연구에서는 hydroxy polyimide (HPI)로 용매 증발법에 의해 제조가 되었다. 비다공성막의 기체투과성능측정 결과로써, $CO_2$ 투과도는 약 85 Barrer이고, $CO_2/N_2$선택도는 23으로 측정되었다. 고분자, 용매, 비용매-첨가제의 3성분계 시스템을 도입하여 평막과 중공사막을 제조하였고, 모폴로지와 기체투과성능을 전계방출형전자주사현미경과 버블플로우메타로 측정하였다. 평막과 중공사막에서 $CO_2$투과도와 $CO_2/N_2$ 선택도는 각각 18.28 GPU, 70 GPU를 6.72, 8.63으로 나타남을 확인하였다. 중공사막이 평막보다 기체투과특성이 우수하다는 것을 확인하였다.