• Nuclear Engineering and Technology
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• 제45권3호
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• pp.335-346
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• 2013

The Critical Heat Flux (CHF) of water with dispersed alumina nanoparticles was measured for the geometry and flow conditions relevant to the In-Vessel Retention (IVR) situation which can occur during core melting sequences in certain advanced Light Water Reactors (LWRs). CHF measurements were conducted in a flow boiling loop featuring a test section designed to be thermal-hydraulically similar to the vessel/insulation gap in the Westinghouse AP1000 plant. The effects of orientation angle, pressure, mass flux, fluid type, boiling time, surface material, and surface state were investigated. Results for water-based nanofluids with alumina nanoparticles (0.001% by volume) on stainless steel surface indicate an average 70% CHF enhancement with a range of 17% to 108% depending on the specific flow conditions expected for IVR. Experiments also indicate that only about thirty minutes of boiling time (which drives nanoparticle deposition) are needed to obtain substantial CHF enhancement with nanofluids.

• Bulletin of the Korean Chemical Society
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• 제27권2호
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• pp.211-218
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• 2006

This work deals with 24 substances composed of nitrogen-containing heterocycles. The relationships between the chromatographic retention factor (k) and those physicochemical properties which are relevant in quantitative structure-properties relationship (QSPR) studies, such as the polarizability $(\alpha)$, molar refractivity (MR), lipophilicity (logP), dipole moment $(\mu)$, total energy $(E_{tot})$, heat of formation $(\Delta H_f)$, molecular surface area $(S_M)$, and binding energy $(E_b)$, were investigated. The accuracy of the simple linear regressions between the chromatographic retention and the descriptors for all of the compounds was satisfactory (correlation coefficient, $0.8 \leq r \leq 1.0$). The QSPR models of these nitrogen-containing heterocyclic compounds could be predicted with a multiple linear regression equation having the statistical index, r = 1.000. This work demonstrated the successful application of the multiple linear approaches through the development of accurate predictive equations for retention factors in liquid chromatography.

• 설비공학논문집
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• 제19권1호
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• pp.1-9
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• 2007

Water condensate accumulated on the surface of a fin-and-tube heat exchanger significantly affects its thermal and hydraulic performance. The purpose of this study is to investigate the effect of condensate retention on the air-side heat transfer performance and flow friction. Total 12 samples of slit and plate fin-and-tube heat exchangers with varying fin spacing and number of tube rows are tested under dry and wet conditions. The thermal fluid measurements are made using a psychometric calorimeter. Frontal air velocity varies in the range from 0.7 m/s to 1.5 m/s. Using the experimental data, presented are the heat transfer coefficients in terms of Colburn j-factor and friction factor.

• 한방비만학회지
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• 제11권1호
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• pp.25-34
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• 2011

Objectives The purpose of this study was to examine the characteristics of diagnostic pattern questionnaire associated with Body Mass Index in premenopausal women. Methods We studied 41 patients visiting Gangdong Kyung Hee University Hospital from 1st April 2011 to 25th May 2011. The subjects were categorized in two groups, overweight & obesity group (n=12) and low weight & normal group (n=29). We studied the difference of diagnostic pattern questionnaire scores between two groups by Independent samples T-test and correlation between diagnostic pattern questionnaire scores of overweight & obesity group by Pearson's correlation coefficient test using SPSS for windows (version 13.0). Results Blood stasis, retention of undigested food, cold pattern scores of overweight & obesity group were non-significantly higher than low weight & normal group. Heat pattern score of overweight & obesity group was significantly higher than low weight & normal group. Cold-heat, phlegm-cold, blood stasis-cold, phlegm-blood stasis, phlegm-retention of undigested food significantly showed positive correlation coefficient in overweight & obesity group. Conclusions The results suggest that obese women tend to show heat pattern. It seems to be that multiple factors such as phlegm, blood stasis, retention of undigested food are causative of obesity.

• Asian-Australasian Journal of Animal Sciences
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• 제6권2호
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• pp.197-203
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• 1993

The protection of dry matter and nitrogen from rumen degradation of dhaincha seed (Sesbania aculeate) meal was studied using nylon bag technique. The dhaincha seed meal was subjected to various heat treatments that included oven drying, autoclaving and boiling. Similar experiment was conducted with fish meal as reference for comparison. The oven-dried dhaincha meal was found to retain more dry matter and nitrogen than was found boiled or autoclaved meal. While autoclaving appeared to improve nitrogen and dry matter retention to some extent, boiling seemed to cause more loss of dry matter from nylon bag. Heat treatment caused high retention of nitrogen by fish meal. The calculated effective protein degradation was 80.4% and 83.2% for the oven dried fish meal and dhaincha seed meal whereas same values were 74.2% and 86.7% for autoclaved fish and dhaincha seed meal respectively at the outflow rate of 4.4% per hour. The in vitro study revealed higher digestibility for heat treated samples by pepsin. The dry matter, nitrogen and ash content of dhaincha seed meal were 85.93%, 5.93% and 7.31% respectively.

• 구강회복응용과학지
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• 제16권2호
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• pp.123-132
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• 2000

The field of maxillofacial prosthetics is concerned with the prosthetic reconstruction of missing head and neck tissue. Currently, facial prostheses are usually applied in cases of defects caused by the surgical removal of tumors or congenital defects. While silicone has been most widely used for the reconstruction of missing maxillofacial defects, it does not have ideal physical properties. Therefore, bonding a thin polyurethane sheet to silicone prostheses was recommended. In this case skin adhesives were used for the retention of maxillofacial prostheses. But retention of devices has always been problematic. The contributions of implants can be made to solve these problems. Implants have reduced the need for adhesive use, simplifying cleaning procedures and thus extending the life of the prostheses. For implant-retained prostheses, retentive matrix is necessary to hold attachments and/or magnets. The retentive matrix is usually fabricated with autopolymerizing acrylic resin or visible light- polymerized resin. The purpose of this study was to compare the adhesion-in-peel force of silicone adhesive to autopolymerizing acrylic resin and polyurethane sheet with two different surface textures : pumice polish only or retention groove, and three surface primers : Dow corning 1205 primer or Dow corning S-2260 primer or FactorII A-304 primer, and two polymerization methods : room temperature or dry heat oven. The t-peel bond strength of specimens was determined as described in ASTM Standard D1876-72. The results were statistically analyzed using the ANOVA test, multiple range test and t-test The results were as follows. 1. The t-peel bond strength of A-304 primer was the highest and statistically higher than that of S-2260(p<0.05). 2. The t-peel bond strength of specimens with retention groove was statistically higher than that of specimens polished with pumice(p<0.05). 3. The t-peel bond strength of specimens polymerized in dry heat oven was statistically higher than that of specimens in room temperature(p<0.01).

• International Journal of Air-Conditioning and Refrigeration
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• 제17권1호
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• pp.7-14
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• 2009

Water condensate accumulated on the surface of a fin-and-tube heat exchanger significantly affects its thermal and hydraulic performances. The purpose of this study is to investigate the effects of condensate retention on the air-side heat transfer performance and flow friction for various flow and geometric conditions. Total of twelve samples of slit and plate fin-and-tube heat exchangers are tested under dry and wet conditions. The thermal fluid measurements are made using a psychrometric calorimeter. Frontal air velocity varies in the range from 0.7 m/s to 1.5 m/s. Using the experimental data, presented are heat transfer coefficients in terms of Colburn j-factors and friction factors, and these data are compared with the existing correlations.

• 한국수산과학회지
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• 제2권2호
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• pp.105-133
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• 1969

김(해태)의 중요색소인 chlorophyll, carotenoid, phycobilin 색소의 가공 및 저장중의 안정도를 실험하였다. 생김의 색소함량, 생김의 저온저장, 초제$\cdot$건조김의 열 처리, 열 처리한 김의 실온저장시에 일어나는 이들 색소의 면화에 대한 실험 결과를 요약하면 다음과 같다. 1. 생김의 chlorophyll a, xanthophyll (lutein+zeaxanthin), 및 carotene ($\alpha-+\beta-carotene$)의 함량은 각각 1,525, 627, $409{\mu}g/g$였고 $\beta-carotene$, lutein, zeaxanthin, 및 $\alpha-carotene$의 비교 함량은 33.7, 35.9, 12.2, $5.8\%$의 순이었다. 2. 생김을 실온($20^{\circ}-25^{\circ}C),\;2^{\circ}\~5^{\circ}C$, 및 $-15^{\circ}C$에서 저장하였을 때색소의 감소는 대체로 $2^{\circ}\~5^{\circ}C$때가 다른 조건에서 보다 적었는데 carotene만은 $-15^{\circ}C$때가 $2^{\circ}\~5^{\circ}C$때 보바 다소 남은 결과였다. Phycocyanin은 Phycoeythrin 보다 많은 감소를 보였다. 3. 초제$\cdot$일건한 김 또는 초제 직후의 김을 $40^{\circ},\;60^{\circ},\;80^{\circ},\;100^{\circ}C$에서 열 처리하였을 때 양자의 경우 모두저온에서 처리할수록 색소감소가 적었고 carotenoid는 전자보다 후자의 경우 감소량이 적었다. Carotenoid중 xanthophyll은 carotene보다 열에 안정하였다. Phycoerythrin은 phycocyanin보다 열에 불안정한 경향이 였는데 높은 온도일수록 현저하였다. 4. 열 처리한 김을 50일간 저장하였을 때, 색소의 변화는 열 처리 온도에 따라 다소의 차는 있었으나 $60^{\circ}C$에서 처리한 것이 대체로 감소량이 적었다. 그러나 큰 차이는 없었다. Xanthophyll, carotene, phycobilin은 모두 고온에서 처리한 것이 저장중의 색소 감소율이 낮았고 따라서 장기저장이 가능한 것 같은 경향을 나타내었다. Xanthophyll과 carotene은 일광건조하지 않고 열 처리한 것에서 감소가 적은 만면 chlorophyll a는 일건 열 처리한 것에서 낮은 감소를 보였다. 5. 색소의 안정도와 분해반응의 억제를 감안한 열처리조건은 $60^{\circ}C$에서 $6.0\%$ 정도의 수분량을 유지할 때까지 처리하거나 그 이상의 고온에서 처리하되 열에 의한 색소의 분해를 최소한으로 하는 시간으로 한정하는 것이 적당하다고 보았다. 6. 김초제액의 PH조절은 저장중에 있어서의 chlorophyll a의 안정화에 효과가 있었으며 pH 7.8일 때가 성적이 좋았다. 초제액에 한천, 알긴산등의 해조추출물을 첨가하였을 때 김의 균일한 성형과 율택의 증진에 효과가 있었다.

• Nuclear Engineering and Technology
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• 제55권1호
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• pp.180-189
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• 2023

We measured the heat load to a reactor vessel with and without the in-vessel debris bed under an IVR-ERVC condition. Mass transfer methodology was adopted based on heat and mass transfer analogy to achieve high Ra'_H of order ~10¹⁵ with compact test rigs. We postulated the in-vessel debris bed has a flat top and particulate debris was simulated as an identical diameter spheres. We conducted experiments varying the height of the debris bed and the results showed that Nusselt numbers decreased in both uppermost and curved surfaces with the increasing bed height. Once the debris bed is formed, it acts as an obstacle to the natural convective flow, which reduces the buoyancy. The reduction of driving force results in the impaired heat transfer in both upward and downward heat transfers.

• Journal of the Korean Wood Science and Technology
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• 제41권3호
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• pp.173-180
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• 2013

PEG 주입을 통해 열처리 중 목재의 균열을 방지하기 위한 연구에 필요한 기초자료를 제공하기 위해 본 연구가 수행되었다. 국내에서 사용되는 대표적인 침엽수 세 수종의 소시편을 이용하여 PEG 분자량에 따른 침투 속도와 잔류량, 열처리 후 잔류량, 평형함수율 등을 조사하였다. PEG400의 평균 잔류량은 수종별 기본밀도에 반비례하였으며 다른 분자량 PEG에서도 비슷한 경향을 나타냈다. 한 수종 내에서는 PEG 분자량이 클수록 잔류 PEG 양이 감소하는 경향이 뚜렷하다. PEG 주입에 의해 함수율이 2% 내에서 증가하거나 감소하였으며, 시편의 평균 기본밀도는 최고 16.8%까지 증가하였다. 열처리에 의한 중량감소율은 PEG400 시편이 PEG600, PEG1000 보다 컸다. 낮은 분자량의 PEG가 더 많이 용출되었다고 볼 수 있다. 평형함수율은 상대습도가 낮을 때(32%RH) 세 수종 모두 PEG 주입 시편과 무처리 시편의 차이가 없었으나, 상대습도가 증가할수록 PEG 주입 시편이 무처리 시편보다 높게 나타났다.