• Applied Chemistry for Engineering
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• v.16 no.6
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• pp.848-852
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• 2005

The two important problems to solve before the industrialization of the iodine-sulfur (IS) process are (i) methods to separate $H_2SO_4$ and HI and (ii) to maintain constant components. However undesired reaction was occurred and $H_2S$ and S were formed during the Bunsen reaction. It is necessary to forbid the undesired reaction between $H_2SO_4$ and HI by separating the two acids into two different layers. The experimental conditions for the present study was chosen in such a way that to achieve the separation between the two acids and minimize the side reaction. $H_2S$ formation was reduced and the separations of the two liquids were occurred at $H_2O$ molar fraction from 0.86 to 0.909. But the separations between the two liquids were not occurred at $H_2O$ molar fraction more than 0.92.

• Proceedings of the Korean Nuclear Society Conference
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• 1998.05b
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• pp.72-77
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• 1998

액체금속로 노심재료로 사용되고 있는 HT9강의 열처리에 따른 미세조직 변화를 관찰하였다. 열간압연상태에서의 조직은 마르덴사이트, $\delta$-페라이트, 잔류 오스테나이트, 그리고 탄화물로 이루어져 있다. 잔류 오스테나이트는 austenitization하여도 그 함량은 감소하지만 완전히 제거되지는 않았으나, tempering후에는 잔류하지 않았다. 오스테나이트 입자크기는 austenitization 온도가 증가함에 따라 성장하여 11005$^{\circ}C$에서는 약 42$\mu\textrm{m}$였다. Austenitization 온도 증가에 따라 탄화물의 평균 크기 및 평균 면적 분율은 크게 감소하고 있었다. 50$0^{\circ}C$에서 tempering한 경우에는 Fe-rich 탄화물이 석출하였으나, tempering 온도가 증가하면 Cr-rich M$_2$$_3$C$_{6}$ 탄화물이 석출하고 있었다. Austenitization 상태에서는 100$0^{\circ}C$ 까지는 탄화물의 분해가 일어나 경도값이 증가하나 100$0^{\circ}C$ 이상에서는 일정한 경도값을 나타내었다. Tempering한 시편에서는 탄화물의 석출과 전위의 회복으로 인해 tempering 온도가 증가함에 따라 경도값이 급격히 감소하였다.

• Korean Chemical Engineering Research
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• v.49 no.6
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• pp.816-822
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• 2011

Pervaporation is known to be a low energy consumption process since it needs only an electric power to maintain the permeate side in vacuum. Also, the pervaporation is an environmentally clean technology because it does not use the third material such as an entrainer for either an azeotropic distillation or an extractive distillation. In this study, Silicalite-1 particles are hydrothermally synthesized and polydimethylsiloxane(PDMS)-zeolite composite membranes are prepared with a mixture of synthesized Silicalite-1 particles and PDMS-polymer. They are used to separate n-butanol from its aqueous solution. Pervaporation characteristics such as a permeation flux and a separation factor are investigated as a function of the feed concentration and the weight % of Silicalite-1 particles in the membrane. A 1,000 $cm^3$ aqueous solution containing butanol of low mole fraction such as order of 0.001 was used as a feed to the membrane cell while the pressure of the permeation side was kept about 0.2~0.3 torr. When the butanol concentration in the feed solution was 0.015 mole fraction, the flux of n-butanol significantly increased from 14.5 g/ $m^2$/hr to 186.3 g/$m^2$/hr as the Silicalite-1 content increased from 0 wt% to 10 wt%, indicating that the Silicalite-1 molecular sieve improved the membrane permselectivity from 4.8 to 11.8 due to its unique crystalline microporous structure and its strong hydrophobicity. Consequently, the concentration of n-butanol in the permeate substantially increased from 0.07 to 0.15 mole fraction. This composite membrane could be potentially appliable for separation of n-butanol from insitu fermentation broth where n-butanol is produced at a fairly low concentration of 0.015 mole fraction.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2011.04a
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• pp.340-344
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• 2011

건축물 마감재료의 연소시 발생되는 독성가스는 대형화재로 인한 인명피해의 주된 원인 중의 하나이다. 현행 건축법에서는 건축물마감재료에 대하여 동물의 평균행동정지시간을 측정하는 가스유해성시험을 실시하고 있다. 본 연구는 동물시험이 아닌 NFPA 269에 의한 유효량분율(FED: Fractional effective does)을 이용하여 건축물 마감재의 독성지수를 도출하였다. 현행 가스유해성 평가 방법에서 사용되는 채임버(피검상자)를 이용하여 적외선분광분석 및 산소분석기로 연소가스를 정량 분석하였으며, NFPA269에서 규정하는 FED를 도출하였다. 몇 가지 건축재료에 대한 가스유해성시험의 평균행동정지시간과 FED의 상대적인 비교를 통해 연소가스독성평가를 수행하였다.

• Korean Journal of Agricultural and Forest Meteorology
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• v.26 no.2
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• pp.127-139
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• 2024

Climate change has increased extreme weather events likewise heatwaves, heavy rain, and drought. Unlike other natural disaster, drought is a slowly developing phenomenon and thus drought damage increases as the drought continues. Therefore, it is necessary to understand the characteristics and mechanism of drought occurrence. Agricultural drought occurs when the water supply needed by crops becomes insufficient due to lack of soil water. Therefore, soil water is used as a key variable affecting agricultural drought. In this study, we examined the spatio-temporal distribution and trends of drought across the Korean Peninsula by determining the soil available water content (SAWC) through a model that integrated soil, meteorological, and crop data. Moreover, an investigation into the correlation between meteorological variables and the SAWC was conducted to assess how meteorological characteristics influence the nature of drought occurrences. During the soybean cultivation period, the average SAWC was lowest in 2018 at 88.6% and highest in 2021 at 103.2%. Analysis of the spatial distribution of SAWC by growth stage revealed that the lowest SAWC occurred during the flowering stage (S3) in 2018, during the leaf extension stage (S2) in 2019, during the seedling stage (S1) in 2020, again during the flowering stage (S3) in 2021, and during the seedling stage (S1) in 2022. Based on the average SAWC across different growth stages, the frequency of upland drought was the highest at 22 times during the S3 in 2018. The lowest SAWC was primarily influenced by a significant negative correlation with rainfall and evapotranspiration, whereas the highest SAWC showed a significant positive correlation with rainfall and relative humidity, and a significant negative correlation with reference evapotranspiration.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.12
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• pp.1091-1097
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• 2013

In this article, an advanced cooling surface based on micro-post arrays with non-homogeneous configurations is investigated and compared with conventional micro-post arrays with homogeneous configuration. The capillary performance of micro-post arrays are characterized using the capillary rate of rise experiments and numerical simulations which take into account the meniscus curvature. The experimental and numerical results show that that the capillary performance of the micro-post wick can be significantly enhanced, compared with the homogeneous type wick, by employing non-homogeneous configurations. The capillary performance is shown to be primarily a function of the solid fraction and increases linearly with decreasing solid fraction, regardless of the wick configuration, when the solid fraction is larger than 0.25. However, the capillary performance is found to be significantly reduced when the solid fraction falls below approximately 0.25.

• Journal of the Microelectronics and Packaging Society
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• v.9 no.4
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• pp.35-45
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• 2002

The stresses of the underfill/chip interface due to thermal loading was studied using the finite element method. At first, the effective properties of underfill for several volume fractions of silica particles were calculated by Mori-Tanaka method for three different material sets, and the parameters of singularity for the bimaterial edge and the bimaterial wedge were calculated. Consequently, the stresses at the underfill/chip interface with volume fraction of silica particles were investigated. Five different geometric models of flip-chip assembly involving two kinds of bimaterial strips and three kinds of three-layer models were considered under the assumption that the underfill is homogeneous. It was assumed that all components of the flip-chip assembly were linear elastic and isotropic, and their properties were temperature independent. The analysis was conducted in the context of the uncoupled plane thermo-elasticity under a plane strain assumption.

• Journal of Convergence for Information Technology
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• v.12 no.3
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• pp.141-150
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• 2022

Fluid flow and thermal characteristics of laminar nanofluid(water/Al2O3) flow in a circular U-bend tube have been studied numerically. In this study, the effect of Reynolds number and the solid volume fraction and the impact of the U-bend on the flow field, the heat transfer and pressure drop was investigated. Comparisons with previously published experimental works on horizontal curved tubes show good agreements between the results. Heat transfer coefficient increases by increasing the solid volume fraction of nanoparticles as well as Reynolds number. Also, the presence of the secondary flow in the curve plays a key role in increasing the average heat transfer coefficient. However, the pressure drop curve increases significantly in the tubes with the increase in nanoparticles volume fraction.

• Nuclear industry
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• v.16 no.5 s.159
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• pp.59-68
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• 1996

한국원자력연구소는 최근 원자력 선진국인 프랑스로부터 원자로 격납 용기 실험 용역 사업을 국내 최초로 수주, 그동안 꾸준히 수행해 온 중대 사고에 대한 원전 안전성 확보를 위한 연구 성과를 국외에서 인정받게 되었다. 본 실험의 목적은 프랑스 900MWe 표준 원전 캐비티 모형에 대한 중대 사고시 고압 방출에 의해 캐비티 밖으로 방출되는 용융 노심 파편물의 방출량을 측정하고, 방출분율을 예측하는 상관식의 검증과 캐비티의 구조 특성을 고려할 수 있는 상관식을 개발하는 것으로서, 금년 2월부터 내년 1월까지 수행한다.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1996.10b
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• pp.150-156
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• 1996

본 연구에서는 Alaska Usibelli 아역청탄이 사용되는 실린더형 석탄 가스화기내에서 석탄의 입자크기가 반응성 유동장과 주요 생성물의 농도분포에 미치는 영향을 고찰하기 위하여 미분탄 입자의 크기를 40$mu extrm{m}$, 60$\mu\textrm{m}$, 100$\mu\textrm{m}$, 120$\mu\textrm{m}$ 및 140$\mu\textrm{m}$로 각각 나누어 전산모사를 수행하였다. 모사결과, 가스화기 내에서 석탄의 입자크기가 가스화 생성물의 농도와 유동장에 커다란 영향을 미침을 알 수 있었다. 입자의 크기가 100$\mu\textrm{m}$일 때 가스화기 출구에서 주 생성물인 CO와 H2가 초대로 생성되고 이때 이들의 평균 몰분율은 각각 0.62, 0.16(dry basis, inert free)으로 예측되었다.