• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.11 no.6
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• pp.880-890
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• 1999

The purpose of this study is to investigate the performance of an autocascade refrigeration system using the refrigerant miktures of R744 (carbon dioxide) and R134a (1,1,1,2-tetrafluoroethane) as working fluids by simulation and experiment. Cycle simulation using a constant UA model in heat exchangers has been performed for R744/134a mixtures of the compositions in the range of from 10/90 to 30/70 by weight percentage. Variations of mass flow rate of refrigerant, compressor work, refrigeration capacity and COP with respect to mass fraction of R744/134a mixture were presented. Performance test has been executed in an autocascade refrigeration system by varying secondary fluid temperatures at evaporator and condenser inlets. Experimental results show similar trend with those from the simulation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.7
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• pp.1642-1647
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• 2009

Changes in aerosol characteristics during 2006 ${\sim}$2008 Asian dust events in Cheoan were investigated by measuring mass, ion and elemental concentrations of fine and coarse particles. The average mass concentrations of daily TSP, PM10, PM2.5 were 214.9, 160.3, and 95.9${\mu}\;g/m^3$during Asian dust events, which were 3.08, 2.58, and 1.95 times higher than Non-asian dust events. The maximum concentrations of TSP, PM10, and PM2.5 were 850.1, 534.4, and 233.3${\mu}\;g/m^3$, which were 12.19, 8.60, and 4.76 times higher, respectively. Increases in ion concentrations were not significant during Asian dust events, but elemental concentrations including soil components such as Fe, Al, Ti increased by 17.1 and 43.4 times for fine and coarse particles, respectively. The results clearly indicate that metallic components from soil constituents were the major components in Asian dusts sampled at Cheonan.

• Proceedings of the Korean Nuclear Society Conference
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• 1998.05b
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• pp.527-532
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• 1998

모의 폐액으로 부터 팔라디움을 회수하여 촉매를 제조하였다. 모의 폐액은 장수명핵종 소멸처리 전환시의 군분리 공정에서 발생하는 8성분 폐액으로 하였다. 팔라디움의 회수율은 99.5% 이상이며, 그 순도는 99% 이상의 고품질의 것이었다 회수된 팔라디움을 사용하여 소수성촉매를 제조하였으며, 이 촉매는 400$m^2$/g 이상의 높은 비표면적을 갖는 것으로 나타났다. 질량비로 10%의 시제품촉매를 제조하여 93%의 삼중수소 교환반응효율을 얻을 수 있었다.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.6
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• pp.1159-1170
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• 2000

It is necessary to improve the ambient air quality through the proper treatment and control of pollutants by designating air pollutants to regulatory ones. Especially, human took a concern for particulate matters which raised visibility reduction, public health effects and injury of property for urban areas. In order to reduce the effect of particulate matters, we need to establish proper control strategies based on the concentration characteristics of particulate matters. In this study. to evaluate the characteristics of $PM_{2.5}$ and $PM_{10}$. thirty-eight samples of $PM_{2.5}$ and $PM_{10}$ were collected at Nam-Gu sampling site where continuous air monitoring system has been operated, from May, 1999 to November, 1999, and their concentrations for the mass and anion components($Cl^-$, $NO_3{^-}$, $SO_4{^{2-}}$) were analyzed. The important conclusions obtained in this study were as followings. Total average mass concentrations of $PM_{2.5}$ and $PM_{10}$ were 35.016 and $50.293{\mu}g/m^3$ respectively. and $PM_{2.5}/PM_{10}$ ratio was calculated 0.692. Total average concentrations of anion components in $PM_{2.5}$ were $1.581(Cl^-)$, $3.690(NO_3{^-})$ and $12.825(SO_4{^{2-}}){\mu}g/m^3$ and those in $PM_{10}$ were $2.471(Cl^-)$, $5.819(NO_3{^-})$ and $14.414(SO_4{^{2-}}){\mu}g/m^3$ respectively. From the correlations analysis. the correlation coefficient between mass concentration of $PM_{2.5}$ and $PM_{10}$ was calculated as 0.945. The correlation coefficients between $PM_{2.5}$ and anion components were analyzed as $Cl^-$(0.025), $NO_3{^-}$(0.788) and $SO_4{^{2-}}$(0.500) respectively, and the correlation coefficients between $PM_{10}$ and anion components were analyzed as $Cl^-$(-0.019), $NO_3{^-}$(0.806) and $SO_4{^{2-}}$)(0.535) respectively.

• Journal of Bio-Environment Control
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• v.20 no.1
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• pp.14-20
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• 2011

Objective of this research was to investigate the volatile aroma compounds and phenol contents for preservative effects. Aerial part of 5 Korean natured species of thyme located in Jeju alpine, jeju middle mountain, Kyeonggido, Ulleung island, and Gangwondo was analyzed by thermal desorption gas chromatograph mass spectrometer (TD-GC-MSD) method. Jeju middle mountain thyme was relatively high 62 species and has been investigated a high concentration of $7365.22{\mu}g/m^3$ contents according to the quantitative analysis. Total phenol contents containing thymol and carvacrol of Jeju middle mountain thyme were relatively high and showed 35.92%.

• Journal of Korea Multimedia Society
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• v.14 no.10
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• pp.1262-1274
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• 2011

A fast and stable deformation model is essential for realistic simulation of image morphing. In order to stabilize deformation, we used two internal thin plate mass-spring systems that compute the displacements of the x- and y-components of all nodes on the mesh. The deformation results are globally smoother and more stable due to the direction limitation of thin plate mass-spring systems. One-to-one deformation is one of the important issues in image morphing. We focus on fast removing overlaps in the process of deformation. To rapidly remove overlaps, the external forces are set automatically on four or eight neighboring nodes. The speed of removing overlaps is faster when external forces are set on four or eight neighbouring nodes than when on two neighbouring nodes.

• Applied Chemistry for Engineering
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• v.30 no.2
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• pp.155-159
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• 2019

As a part of improving the quality for the fraction of the waste plastics pyrolysis oil (WPPO), the recovery of paraffin components contained in the fraction was investigated by dimethylformamide (DMF) equilibrium extraction. The fraction of a distilling temperature of $120{\sim}350^{\circ}C$ recovered from WPPO by the simple distillation and the aqueous solution of DMF were used as a raw material and solvent, respectively. The concentrations of paraffin components ($C_{12}$, $C_{14}$, $C_{16}$ and $C_{18}$) contained in the raffinate decreased by increasing the mass fraction of water in the solvent at an initial state ($y_{w,0}$), whereas, the concentrations of paraffin components contained in the raffinate increased by increasing the mass ratio of the solvent to the feed at an initial state $(S/F)_0$. The concentrations of $C_{12}$, $C_{14}$, $C_{16}$ and $C_{18}$ paraffin components present in the raffinate recovered at $(S/F)_0=10$ were about 1.37, 2.0, 2.46 and 3.16 times higher than those of the raw materials, respectively. Recovery rates (residue rates present in raffinate) of paraffin components rapidly increased with increasing $y_{w,0}$, and decreasing $(S/F)_0$. The raffinate recovered through this study was expected to be used as a renewable energy.

• Proceedings of the Korean Nuclear Society Conference
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• 1997.05b
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• pp.217-222
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• 1997

핵연료 물질인 금속 우라늄과 이산화 우라늄의 플라즈마 기체에 의한 에칭 연구가 수행되었다. 연구에 사용된 플라즈마 기제는 CF$_4$와O$_2$의 혼합기체이며 CF$_4$/O$_2$의 혼합비. 시편 표면의 온도, R.F power, 그리고 압력에 따른 에칭율을 측정하였다. L-metal의 경우는 R.F power를 50W로 고정하고 아주 낮은 $O_2$의 성분비와 반응시간에 따른 에칭정도를 질량결손으로 계산하였다. $UO_2$의 에칭에 있어서는 CF$_4$/O$_2$의 비가 4:1에서 가장 높은 에칭율을 보였으며 그 에칭율은 최대 1000 monolayers/min 이었으며 U-metal의 경우 그 에칭율은 $UO_2$와 비교하여 10배 가량 낮은 것으로 나타났다.

• Proceedings of the Korean Nuclear Society Conference
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• 1997.10a
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• pp.784-789
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• 1997

원자력 발전소에서의 중대사고시, 고온의 노심 용융물이 원자로 공동으로 떨어지면 노심용융물과 콘크리트간의 반응(MCCI)에 의한 여러가지 현상으로 인해 격납용기의 건전성을 위협할 수 있다 본 연구에서는 국내 원전에서의 MCCI 현상에 대한 실험과 해석결과를 살펴보았다. 실험은 영광원전 3,4호기 원자로 공동구조물의 콘크리트를 대상으로 thermite 20kg을 사용한 것이며 해석은 MELCOR 코드내의 MCCI 상세해석 모듈인 CORCON-MOD3를 이용하였다. 해석에 사용된 콘크리트의 화학성분과 열물성은 실험을 통하여 측정한 값을 사용하였으며 해석결과는 실험 결과와 비교하였다. 또한 GORCON 코드에서의 MCCI 현상의 해석시 용융물의 초기온도, 용융물의 질량, 콘크리트의 종류에 따른 예측결과들을 비교하였다. MCCI 현상의 해석시 콘크리트의 종류에 따른 가스발생량과 구성성분의 변화가 크게 나타남으로 콘크리트의 화학적 구성성분을 적합하게 입력하여야 한다. 콘크리트로의 종류에 따른 하부로의 열유속은 크게 차이가 없으나 침식율은 크게 차이가 나며 이는 콘크리트의 상변화 잠열의 차이에서 기인한 것이다. CORCON 코드는 실험에 비해 작은 침식율을 예측하고 있으며 콘크리트의 침식율은 용융물의 양에 비해 초기온도의 변화에 더 큰 영향을 받는 것으로 예측하고 있다.

• Journal of the Korean Society of Food Science and Nutrition
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• v.35 no.10
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• pp.1378-1384
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• 2006

A survey was conducted for 221 male and 191 female college students to study correlations between dietary food intakes and body composition. Among the subjects 75 male and 82 female students were analyzed body protein mass, body mineral mass, percent body fat, waist-hip ratio (WHR), body mass index (BMI) and fitness score using Inbody 3.0. The results show that 94.6% of the males and 24.7% of the females were observed at high level in body protein mass. As for body mineral mass, 86.4% of the males were observed below the normal range. As for WHR, 32.1% of the males and 43.5% of the females were evaluated as abdominal obesity. As for BMI, 34.8% of the males were observed above the normal range. In female students, correlation coefficient between sodium intakes and age showed significantly negative 0.232 while correlation between calcium intakes and self-reported health status showed significantly positive 0.234. In males, correlation coefficient between fiber intakes and self-reported health status resulted in significantly positive 0.237 and that between BMI and age showed significantly positive 0.276. In females, correlation coefficient between type of living and WHR showed significantly positive 0.253 and that between self-reported health status and percent body fat showed significantly positive 0.230. Also correlation coefficient between body protein mass and sodium intakes showed significantly negative 0.276 in female students.