• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2005년도 후기학술대회논문집
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• pp.244-245
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• 2005

This paper presents the heat transfer and pressure drop characteristics during cooling process of carbon dioxide in a horizontal tube. The test section is a tube in tube type heat exchanger with refrigerant flowing in the inner tube and water flowing in the annulus. It was made of a stainless steel tube with the inner diameter of 7.75 [mm], the outer 2 diameter of 9.53 [mm] and length of 6000 [mm]. The refrigerant mass fluxes were $200{\sim}400$ [kg/$m^2s$] and the average pressure varied from 7.5 [MPa] to 10.0 [MPa]. The main results were summarized as follows The heat transfer coefficient of supercritical $CO_2$ increases in decrease of the gas cooler pressure. And the heat transfer coefficient increases with respect to the increase of the refrigerant mass flux. Among some correlations proposed in a transcritical region, Bringer-Smith's correlation has some analogy with experimental results. The pressure drop decreases in increase of the gas cooler pressure and increases with respect to increase the refrigerant mass flux.

• 한국환경과학회지
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• 제3권4호
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• pp.403-408
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• 1994

Catalytic slurry reactors, in which a solid maintained in the rom of fine particles suspended in a liquid, are frequently used in chemical and biochemical and industries. In these processes the particle loading is normally low so that the effects of particles on the liquid-film mass transfer coefacent and the gas-liquid interface area are assumed to be negligible. But it is known from the works, amongst others, that the finely powdered activated carbon can increase the gas-liquid mass transfer significantly in surface-aerated reactors. The stirred cell (13.2cm inside diameter) contained four baffles and at the stirring speeds range of 80 ∼ 300ppm, the gas-liquid interfacial area could be considered as that of the cross section of the vessel (that is, 130.1cm2). When the stirrer speeds were increased, the effective interfacial area was slightly higher than the geometric area and was obtained experimentally from the Danckwerts plots. Key Words : gas-liquid interfacial area, Duckwert's Plot stirred dell. mass transfer coefficient.

• 한국주조공학회지
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• 제8권3호
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• pp.287-295
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• 1988

The experiment was carried out for the purpose of studying the carburization of pure iron ingot and sintered iron powder by solid carbon in the atmosphere of CO gas. The volocity of carburization was estimaed by the diffusion coefficient D calculated by carburization equation. The results obtained were as follow: 1. The higher the carburization temperature, carburization depth and carbon concentration were increased, and the melting zone which had $2.8{\sim}3.4%C$ at the $3{\sim}4mm$ from interface of carburization was formed at $1300^{\circ}C$. 2. The main carburization mechanism of pure iron ingot and the sintered iron powder were proceeded by CO gas up to $1100^{\circ}C$, solid carbon over than $1300^{\circ}C$, respectively. 3. The main carburization mechanism of pure iron ingot at $1200^{\circ}C$ was proceeded by solid carbon, and sintered iron powder was proceeded bs CO gas, however, in case the reaction time, the carburization was proceeded by solid carbon over than 5hrs. 4. The diffusion coefficient D of carbon were $0.559{\times}10^{-6}cm^2.sec^{-1}$ at $1100^{\circ}C$, $0.237{\times}10^{-6}cm^2.sec^{-1}$ at $1200^{\circ}C$, $0.087{\times}10^{-6}cm^2.sec^{-1}$ at $1300^{\circ}C$, in case of pure iron ingot carburized. 5. The diffusion coefficient D of carbon were $0.124\;cm^2.sec^{-1}$ at $1100^{\circ}C$, $0.102\;cm^2.sec^{-1}$ at $1200^{\circ}C$, $0.480\;{\times}10^{-6}cm^2.sec^{-1}$ at $1300^{\circ}C$, in the case of sintered iron carburized at the pressuring $4ton\;/\;cm^2$.

• 공업화학
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• 제10권3호
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• pp.362-366
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• 1999

Poly(vinyl chloride) (PYC) 유도제들로부터 용매증발법을 이용하여 바이오센서용 막을 제조하고 기체 투과특성을 조사하였다. 진공하에서 용매를 증발시켜서 제조된 막보다 공기 중에서 서서히 증발시켜 제조된 막의 투과도 계수가 더 높은 것으로 나타났다. PVC 유도체 막들에 대한 $CO_2$와 $O_2$의 투과도 계수는 공급부의 압력이 증가함에 따라 감소하였다. Carboxylated poly(vinyl chloride) (CPVC) 에 대한 dioctyl phthalate (DOP)의 첨가량이 증가함에 따라 투과도 계수는 증가하였다. 예를 들면 DOP 30 wt. %를 첨가하였을 때, $CO_2$와 $O_2$의 투과도 계수는 100 psig에서 각각 2.03, 0.96 Barrer 이었으며, DOP를 첨가하지 않았을 때 보다 약 4~5배 증가하였다. Poly(vinyl chloride-co-vinyl acetate) (PVCA)를 가수분해함으로써 OH기가 도입된 poly(vinyl chloride-co-vinyl acetate-co-vinyl alcohoI) (Syn-PVCAcAl)에 DOP를 첨가하였을 때 $CO_2$의 투과도 계수에서 시판제품 PVCAcAl보다 비교적 높은 값을 나타내었으나, $O_2$의 투과도 계수에는 차이가 없었다.

• 한국재료학회지
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• 제16권5호
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• pp.312-317
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• 2006

Binary skutterudite $CoSb_3$ compounds were prepared by the encapsulated induction melting (EIM) process, and their thermoelectric, microstructural and mechanical properties were examined. Single-phase ${\delta}-CoSb_3$ was successfully produced by the EIM and subsequent heat treatment at 773 K-873 K for 24 hours in vacuum. Seebeck coefficient increased with increasing heat treatment temperature up to 673 K, showing the positive signs in the range of measuring temperature. However, the samples heat-treated at 773 K-873 K showed negative Seebeck coefficient from room temperature to 400 K, while it showed positive signs above 400 K. Electrical resistivity decreased with increasing temperature, showing typical semiconducting conductivity. Thermal conductivity decreased drastically with increasing heat-treatment temperature. This is closely related with the phase transition to ${\delta}-CoSb_3$.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2010년도 춘계 학술대회 제22권1호
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• pp.221-222
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• 2010

본 연구에서는 콘크리트 탄산화진행을 보다 정확하게 표현하기 위해 콘크리트 투기계수를 탄산화 진행 모델에 적용하여 $CO_2$, $Ca(OH)_2$ 확산 계수를 유추하는 것이 본 연구의 목적이다.

• Korean Chemical Engineering Research
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• 제54권5호
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• pp.648-652
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• 2016

본 연구에서는 구아니딘계 초염기인 1,1,3,3-테트라메틸 구아니딘(TMG)과 에틸렌 글라이콜로 구성된 비수계 흡수제를 충진탑에 적용하여 이산화탄소 흡수특성을 고찰하였다. 흡수탑은 내경이 1 in이고 높이는 0.6 m이며 탑 내부는 $0.16in{\times}0.16in$의 규격을 갖는 다공 충진물로 채웠다. 흡수탑에서의 이산화탄소 제거 효율에 대한 흡수제 농도, 조업온도 등의 영향 뿐 아니라 이들이 물질전달 저항에 미치는 영향을 고찰하였다. 이산화탄소에 대한 TMG의 로딩값은 약 ${\alpha}=1.0mol_{CO2}/mol_{TMG}$에 달하였으며 이산화탄소가 적게 로딩된 흡수제에서는 총괄 물질전달 계수가 TMG의 농도에 비례하였으나 ${\alpha}=0.5$ 이상의 로딩값에서는 총괄 물질전달계수가 오히려 감소하였다. 이는 흡수제의 이산화탄소에 대한 로딩값에 따른 흡수제 점도 증가로 인한 액체상에서의 물질전달 저항 증가로 해석할 수 있다.

• Journal of Korea Trade
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• 제25권2호
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• pp.58-74
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• 2021

Purpose - This paper research on the embodied carbon emission in Sino-Korea trade. It calculates and analyzes the carbon emission coefficient and specific carbon emissions in Sino-Korea trade from 2005 to 2014. Design/methodology - This paper conducted an empirical analysis for embodied carbon emission in Sino-Korea trade during the years 2005-2014, using a multi-region input-output model. First, direct and complete CO2 emission coefficient of the two countries were calculated and compared. On this basis, combined with the world input-output table, the annual import and export volume and sector volume of embodied carbon emission are determined. Then through the comparative analysis of the empirical results, the reasons for the carbon imbalance in Sino-Korea trade are clarified, and the corresponding suggestions are put forward according to the environmental protection policies being implemented by the two countries. Findings - The results show that South Korea is in the state of net trade export and net embodied carbon import. The carbon emission coefficient of most sectors in South Korea is lower than that of China. However, the reduction of carbon emission coefficient in China is significantly faster than that in South Korea in this decade. The change of Korea's complete CO2 emission coefficient shows that policy factors have a great impact on environmental protection. The proportion of intra industry trade between China and South Korea is relatively large and concentrated in mechanical and electrical products, chemical products, etc. These sectors generally have large carbon emissions, which need to be noticed by both countries. Originality/value - To the best knowledge of the authors, this study is the first attempt to research the embodied carbon emission of ten consecutive years in Sino-Korea Trade. In addition, In this paper, some mathematical methods are used to overcome the error problem caused by different statistical caliber in different databases. Finally, the accurate measurement of carbon level in bilateral trade will provide some reference for trade development and environmental protection.

• Journal of Advanced Marine Engineering and Technology
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• 제29권8호
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• pp.946-952
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• 2005

The $CO_{2}$ refrigeration cycle is expected to reduce the compressor work and increase the COP by applying two-phase ejector as a device for the recovery of dissipated expansion energy. In this study, the performance of the cycle was simulated and effects of the ejector shapes on the performance of the $CO_{2}$ refrigeration cycle were investigated. The following results were obtained through the cycle simulation. The COP of the $CO_{2}$ refrigeration cycle with two-phase ejector flow which expansion is occured in the isentropic manner is increased by a maximum of 24 $\%$ than the basic cycle with expansion valve If the velocity nonequilibrium in the mixing process is assumed the COP of the cycle is increased with the increase of the length and the decrease of the section area of the mixing tube. The best cycle performance is obtained when the divergent angle of diffuser is 7.

• 통합자연과학논문집
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• 제8권1호
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• pp.40-47
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• 2015

Glycogen synthase kinase 3 (GSK-3) is a serine/threonine protein kinase that has recently emerged as a promising target in drug discovery. It is involved in multiple cellular processes and associated with the pathogenesis of several diseases. A three-dimensional quantitative structure-activity relationship (3D-QSAR) analysis was performed on a series of GSK-3 inhibitors to understand the structural basis for inhibitory activity. Comparative molecular field analysis (CoMFA) method was used to derive 3D-QSAR models. A reliable CoMFA model was developed using ligand-based alignment scheme. The model produced statistically acceptable results with a cross-validated correlation coefficient ($q^2$) of 0.594 and a non-cross-validated correlation coefficient ($r^2$) of 0.943. Robustness of the model was checked by bootstrapping and progressive scrambling analysis. This study could assist in the design of novel compounds with enhanced GSK-3 inhibitory activity.