• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.11 no.4
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• pp.537-541
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• 1999

The system performance of a room air conditioner using R410A was experimentally evaluated and compared with that of R22 system. The results indicated that the cooling EER(energy efficiency ratio) of R410A was 1% higher than that of R22 at the outdoor temperature of $35^{\circ}C$. As outdoor temperature increases above $35^{\circ}C$ ambient, EER of the R410A system decreased more substantially compared with R22 system. R410A showed higher compressor discharge temperature than that of R22 system at the outdoor temperature of higher than $50^{\circ}C$.

• 연구논문집
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• s.25
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• pp.77-90
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• 1995

For improving performance of heat pump system, researcher has adapted 2-stage economizer cycle and developed a high-efficiency screw compressor, new working medium(non-azeotropic mixed refrigerant) and counterflow heat exchangers operating with a small temperature difference. Target of this study is development of high performance heat pump system with the 2-stage economizer system using the non-azeotropic mixed refrigerant. For the purpose of excuting target, we constucted computer simulation programs, compared and examed various types of cycle and non-azeotropic mixture. Based on the results from computer simulation we selected optimum mixtures and reflected design and production process of performance test equipment with the 1-stage econmizer system. In order to accomplish the final target, design and production of the 2-stage economizer system, we performed pilot test using the 1-stage economizer performance test system and finally design and production of the 2-stage economizer system.

• Resources Recycling
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• v.8 no.3
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• pp.31-36
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• 1999

In the process of manufacturing acrylonitrile, azeotrope of water-acetonitrile is formed as by-product. To1uene-ethylacetate mixture was selected as solvent to determine the liquid-liquid equilibria for to1uene(l)-water(2)-acetomtrile(3)-ethyjacetate(4) system. The experimental he-line data were correlated with the UNIFAC model. The distribution and selectivity for quaternary system was also studied.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1995.04a
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• pp.61-61
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• 1995

1993년 국내토양으로부터 분리동정된 Streptomyces속 균주중 항종양성이 우수한 균주 3주(DKM104, DKM117, DKM409)를 선정하고 이들을 대량 배양하여 종양억제인자를 분리하고 시험관내 종양세포 독성능 및 생체내 항암활성능과 이들 물질생산과 PLASMID DNA와의 관련성, $LD_{50}$등을 시험하여 새로운 항종양물질의 개발을 목적으로 하였다. 분리선별균주의 배양조건을 확립하였으며 배양여액을 국성이 적은 유기용매로부터 큰쪽으로 단계적으로 유효성분을 추출하여 Gel Chromatography를 이용하여 유효성분을 분획하였다. 시험관내 항종양능 시험은 MTT colorimetric검정법을 이용하여 $IC_{50}$값을 산정하였으며 생체내 항종양능은 마국의 NIC에서 권장하는 tumor panel system에 따랐다. 선정된 균주의 plasmid 분리는 alkalin lysis법을 채택하였으며 agarose gel electrophoresis로 plasmid profile을 시험하였다. Novobiocin등을 이용하여 Curing test를 시행하였고 독성실험은 $LD_{50}$량을 구해 항암효과 측정시에 Maximum dost로 투여하였고 최고용량을 기준으로 일정한 공비를 적응하여 3단계의 투여량을 설정하였다.(중략)

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.14 no.6
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• pp.468-476
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• 2002

This paper deals with heat and mass transfer characteristics and performance evaluation of a counter flow double-tube condenser for a multi-component refrigerant mixture. The local heat and mass transfer characteristics of ternary zeotropic refrigerant mixtures composed of HFC32/HFC125/HFC134a are evaluated for a counter flow double-tube condenser cooled by water. Then, the local values of vapor quality, thermodynamic states at bulk vapor, vapor-liquid interface and bulk liquid, heat flux and condensation mass flux are obtained. The heat exchange performance for ternary zeotropic refrigerant mixtures composed of HFC32/HFC125/HFC134a on the total pressure drop and the heat transfer characteristics are also compared with those for R404A, R410A, R502, R22, R32, Rl23 and R134a.

• Korean Chemical Engineering Research
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• v.46 no.5
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• pp.892-897
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• 2008

A new ethanol dehydration process utilizing a thermally coupled distillation column is proposed to reduce the energy requirement of the existing dehydration processes. An entrainer of benzene is used in the proposed system having the column profile similar to the equilibrium composition profile for the maximum distillation column efficiency, and the feed composition is arranged to close to the boundary of different distillation regions. It is found that the proposed distillation system gives some 18% of energy saving over the existing process. In addition, design guidelines are suggested for other azeotropic distillation process.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.12
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• pp.1049-1056
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• 2000

In this study, condensation heat transfer coefficients(HTCs) of 2 nonazeotropic refrigerant mixtures of HFC32/HFC134a and HFC134a/HCFC123 at various compositions were measured on a horizontal smooth tube. All data were taken at the vapor temperature of 39$^{\circ}C$ with a wall subcooling of 3~8K. Test results showed that HTCs of tested mixtures were 11.0~85.0% lower than the ideal values calculated by the mass fraction weighting of the pure components HTCs. Thermal resistance due to the diffusion vapor film was partly responsible for the significant reduction of HTCs with these nonazeotropic mixtures. The measured data were compared against the predicted ones by Colburn and Drew\`s film model and a good agreement was observed.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.15 no.7
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• pp.563-571
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• 2003

The forty vapor-liquid equilibrium data of the binary system, HFC125＋Propane, were measured between 273.15 and 313.15 K at 10 K interval and the composition range 0.2∼0.75, respectively. Experiments were performed in a circulation type apparatus in which the vapor phase was forced through the liquid phase. The composition at equilibrium were mea-sured by gas chromatography, and its response was calibrated using gravimetrically prepared mixtures. Vapor-liquid equilibrium data were calculated by using CSD equation of state and compared with the experimental data.

• The Mathematical Education
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• v.51 no.3
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• pp.211-221
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• 2012

We discovered that definition of a Geometrical Progression(Sequence) have some differences in domestic textbooks & some foreign countries' books. This will be able to cause a chaos when students divide whether a sequence is a Geometrical Progression(Sequence) or not, and a question error when teachers compose questions about convergence conditions of Infinite Geometric progressions & series. We took a question investigation for students about definition of a Geometrical Progression(that is called G. P.), we discovered that high level students have an error about definition of a G. P.. So We modified expressions of terminology in domestic textbooks appropriately through a Geometrical Progression(Sequence), infinite series, & infinite geometrical series in some foreign countries' books.

• Proceedings of the Membrane Society of Korea Conference
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• 1998.10a
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• pp.115-117
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• 1998

생물 발효 공정에 의해 생산된 부탄올 수용액은 농도가 희박하여 농축 공정이 필요하다. 기존의 농축 공정 중 투과증발공정은 공비혼합물이나 비점이 근접한 혼합물등을 분리하는데 에너지가 적게 들고, 분리 효과가 뛰어나며, 조업이 용이하고, 공정이 차지하는 공간이 적다는 장점을 가지고 있다. 산업적으로 관심을 갖는 5 wt% 이하의 부탄올 수용액을 효과적으로 농축시키기 위해 투과증발공정이 사용된다. 현재 투과증발공정에 사용되는 막에는 elastomeric membrane, plasma treated membrane, UV-grafted membrane, polymer blend membrane이 연구 개발되어 사용되고 있는데, 이중 플라즈마 처리방법을 통해 막을 제조 할 경우, 플라즈마 대상 물질의 선택 폭이 넓고, 분리물과 막간의 친화력을 향상 시키기 위해 분리물과 유사한 화학구조를 갖게 할 수 있으며, 형성된 코팅 층이 crosslinking되어 안정성을 갖는 장점이 있다. 따라서 본 연구에서는 플라즈마 처리법을 통해 투과증발막을 제조하고 제조된 막을 부탄올 농축에 사용하여 막의 성능을 조사하였고, 막의 성능과 접촉 각, sorption, heat of mixing간의 상관 관계에 대해 살펴 보았다.