• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.1226-1231
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• 2009

This paper presents operating characteristics of internal heat exchanger(IHX) for $CO_2$ geothermal heat pump in the heating mode. Mass flow rate of $CO_2$, inlet temperatures of $CO_2$ at high and low pressure side were selected as main effect factors by using fractional factorial DOE(Design of Experiments). And RSM(Response Surface Method) was used in optimization phase. The results show that heat transfer rate of IHX increases when either inlet temperature of low pressure side decreases or inlet temperature of high pressure side increases. Effectiveness of IHX increases with increasing of inlet temperature of either high pressure side or low pressure side. Finally, performance contour map was provided over the operation ranges of the main design factors.

• Journal of Energy Engineering
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• v.13 no.3
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• pp.219-227
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• 2004

World have been encouraged to develop technologies that contribute to CO$_2$ emission reduction for many years. Those technologies can be categorized into capture, storage or sequestration, utilization, etc. There have been lots of efforts, in Korea, to develop the technology as well. In this paper, the impact factors of the technologies, especially in CDRS (Carbon Dioxide Reduction & Sequestration Center), were selected and were weighed by SMM (Storing Models Method) and AHP (Analytic Hierarchy Process) in order to evaluate the four representative areas of the technologies.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.5 no.5
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• pp.480-483
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• 2004

Butylene carbonate(4-ethyl-l,3-dioxolan-2-one), one of the cyclic carbonate was synthesized by the thermal degradation of poly(butylene carbonate). The poly(butylene carbonate) was made from 1,2-Epoxybutane and carbon dioxide which is one of the main green house gas. The prepared cyclic carbonate was identified by GC-Mass. This synthetic method is an alternative way to prepare cyclic carbonates.

• Prospectives of Industrial Chemistry
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• v.23 no.4
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• pp.13-19
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• 2020

수년간 고농도 미세먼지 발생으로 인한 실내공기질 관리방안에 관한 논의가 계속되고 있다. 특히, 시민들이 하루에 1.75시간 이상 지하철 및 버스 등의 대중교통 내에서 머물고 있는 것으로 발표되고 있어 환경부에서는 2019년 대중교통에서의 공기질 관리 방안을 강화하는 것으로 발표한 바 있다. 최근 철도차량 등의 대중교통 차량에서 공기질 개선장치가 도입되고 있는 추세이긴 하나, 대부분의 기존 대중교통차량에서는 공기질 개선장치가 적용되어 있지 않고 대기질이 나쁨인 경우 실내 환기가 어려워 이용 시민들의 건강을 해칠 수 있는 상황이다. 이러한 상황에서 강화되는 실내공기질관리법을 만족하기 위해서는 다양한 대중교통 차량에서의 공기질 관리기술을 토대로 신규차량 뿐만 아니라 기존차량에서 적용할 수 있는 실제적인 논의가 필요하다. 본 기고문에서는 대중교통에서의 공기질 현황을 알아보고 효율적인 공기질개선을 위한 미세먼지 및 이산화탄소 저감에 관한 연구동향을 정리하고자 한다.

• Clean Technology
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• v.9 no.4
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• pp.197-206
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• 2003

We performed removal of aromatic compounds, benzene and toluene, from soil and zeolite using supercritical carbon dioxide. Extraction was performed at $50^{\circ}C$ and 27.7 MPa with changing the extent of pollutant concentration and the results were compared and analyzed. Experiments were carried out using flow method and high pressure extractor of 1.27 cm in diameter and 25cm in length was used. The pollutants were sampled every ten minutes and their concentrations were analyzed with GC/FID. As a result, highly contaminated sample followed solubility/elution model and slightly contaminated sample followed desorption/kinetics model. At the same condition benzene was extracted faster than toluene. In the case of zeolite, more time is required to extract pollutants than soil. This phenomena was due to high adsorption capacity of zeolite. In the case of highly contaminated soil, we could correlate experimental data using simple Brady's fixed bed extractor model. But in the case of slightly contaminated soil, that was governed with desorption/kinetics model, there was some errors.

• Journal of the Korea Society of Computer and Information
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• v.25 no.1
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• pp.117-124
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• 2020

In this paper, we proposed a plan to maintain comfortable indoor air quality in nursing homes by suggesting ways to reduce items temporarily exceeding the reference values through real-time concentration variation analysis of indoor air quality. Five items including PM10, CO₂, CO, VOC, and Radon are measured at nursing homes in spring (April) and autumn (September) was carried out and all of the measured items were analyzed to satisfy the criteria set by the Indoor Air Quality Control Act. As a result of the analysis of the real-time concentration change, the concentration of CO₂ was close to the reference value based on the number of occupants in the sick room. Due to the disinfectant (alcohol) used to disinfect and the auxiliary tools (adhesive) used in the operation of the program such as making and coloring, it was analyzed to temporarily exceed the standard value in the hall. In conclusion, it is possible to provide pleasant indoor air quality and contribute to securing the nursing home's competitiveness if periodic ventilation, natural disinfectant and eco-friendly product are used in consideration of the thermal environment.

• Korean Journal of Food Science and Technology
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• v.31 no.5
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• pp.1300-1307
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• 1999

Supercritical fluid extraction was applied to recycling triglyceride from used shortening. Used shortening and its fractions were analyzed with high performance size exclusion chromatography for their composition in triglycerides, polymer and low molecular weight compounds. Conjugated diene value and color of the fractions were also measured with a UV spectrophotometer and a colorimeter, respectively. Pressure and temperature ranges employed were $15{\sim}30$ MPa and $40{\sim}60^{\circ}C$, respectively. Concentration of fat in supercritical (SC) $CO_2$ ranged from $0.3\;X\;10^{-3}{\sim}7.4\;X10^{-3}(g\;fat/g\;CO_2)$. An exponential relation between concentration of fat in SC $CO_2$ and density was observed. Color of the extracts was light yellow which was very close to that of the fresh shortening. Low molecular weight compounds were preferentially concentrated in the initial fraction, while polymer was extracted in the final fraction. Conjugated diene value of the initial fractions was clearly lower than that of feed. It increased sharply as the polymer content in the fraction became significantly large.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.7
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• pp.200-206
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• 2018

The aim of this study was to evaluate the effect of Ropivacaine on pain following laparoscopic surgery. Between March 2015 and June 2017, all 97 patients with renal mass who elected to receive laparoscopic nephrectomy were reviewed, retrospectively. Normal saline (0.9%) was used as a control in 45 patients while Ropivacaine was used for local anesthesia in the instillation group (n=52). Pain score (visual analog scale) of the shoulder and upper abdominal area between the two groups was significantly different between recovery time and 24 h (p<0.05), with no significant differences between 48 and 72 h (both p>0.05). In the instillation group, pain score of shoulder and abdominal pain in the two groups according to the amount of CO2 used was not significantly different between recovery time and 24, 48, and 72 h (all p>0.05). Ropivacaine reduced shoulder and upper abdominal pain that occurred within 24 h after surgery. Effective pain control with Ropivacaine is needed in the early postoperative period when a large amount of CO2 is used in laparoscopic surgery.

• Korean Chemical Engineering Research
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• v.46 no.3
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• pp.550-554
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• 2008

The synthesis of dimethyl carbonate (DMC) from methanol and supercritical carbon dioxide over $K_2CO_3/ZrO_2$ catalysts have been studied. The catalysts were prepared by impregnating $ZrO_2$ with an aqueous $K_2CO_3$ solution. The optimum calcination temperature to disperse K species on the $ZrO_2$ surface was found to be 673 K. Monoclinic $ZrO_2$ was not active, as itself, for the DMC production. However, when the $K_2CO_3$ was impregnated on the $ZrO_2$, the catalytic performance was improved. Besides the catalyst, $CH_3I$ was used as a promoter. The $CH_3I$ promoter as well as the $K_2CO_3/ZrO_2$ catalyst was found to take an important role to improve the production of DMC. The optimum quantities for the catalyst and the promoter were estimated. The effect of the catalyst and the promoter for the DMC synthesis from methanol and supercritical carbon dioxide was investigated and the reaction mechanism was proposed.

• Journal of the Microelectronics and Packaging Society
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• v.25 no.4
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• pp.105-109
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• 2018

We studied graphene synthesis to porous Cu to improve the characteristics of carbon dioxide reduction of cu. Cu powders were formed through Thermal Chemical Vapor Deposition(TCVD) to Porous Cu/Graphene structures synthesized with graphene. As a result of electrochemical experiments using a 0.1 M $KHCO_3$ electrolyte at an applied potential of -1.0 V to -1.4 V, the current density of Porous Cu/Graphene was 1.8 times higher than that of Porous Cu. As a result of evaluating the product, CO and $H_2$ were generated to Porous Cu electrode. On the other hand, the product of porous Cu/Graphene produced CO, $CH_4$ and $C_2H_4$. It is considered that the graphene causes longer carbon dioxide adsorption time, which means that the intermediates formed during the reaction remain on the electrode surface for a longer time. As a result, it can be concluded that the production reaction of the C2 compound could be continuously performed.