• 대한핵의학회지
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• 제4권2호
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• pp.55-66
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• 1970

Reappraisal measurements of apparent half survival time of red cell by $^{51}Cr$ method was made and effects of blood-letting over red cell survival were observed. The study was performed on 53 normal male subjects under three different experimental conditions. 1. Group 1 Mean $^{51}Cr$ red cell half survival by ACD wash method was 29.7 days. $T\frac{1}{2}$ of Ascorbic acid method was 29.0 days in group with 100 mg dose and 29.1 days in group with 50 mg dose respectively. There was no difference between these two methods in regards to red cell half survival. No difference were noted in amount of ascorbic acid administered. 2. Group 2 As daily amount of blood loss is increased the shortening of red cell half survival was noted. Rapid phase was seen when blood loss ranged 10 to 25 ml per day, while slow phase noted when more loss amounted 25 ml or more daily. Thus, it was clear that there was more than an exponential relation between $T\frac{1}{2}$ and the amount of blood loss. 3. Group 3 $T\frac{1}{2}$ measured by cpm per whole blood was within normal range and $T\frac{1}{2}$ measured by cpm per red cell mass showed shortening tendency when compared with the former in the group measured after blood loss (from 25 ml daily up to 100 ml daily in 10 days). In the group with rather constant blood loss of 100 ml daily for 10 consecutive days revealed the significant difference in two measurements (P<0.01). 4. $T\frac{1}{2}$ in non-steady state When red cell production is increased compared with red cell destruction, $T\frac{1}{2}$ measured by cpm per red cell mass being shorter than that by cpm per whole blood. Shortening of $T\frac{1}{2}$ measured by cpm per whole blood is more prominent. if red cell destrction is enhanced and exceeds production. 5. It is clear that when expressing red cell destruction rate, $T\frac{1}{2}$ measured by cpm per whole blood is more adequate and production more consistent with cpm red cell mass. 6. $T\frac{1}{2}$ measured during blood-letting, when corrected by amount of blood loss, it remains normal. It is erroneous to use conventional equational when measuring $T\frac{1}{2}$ in non-steady. $T\frac{1}{2}$ measured by cpm per whole blood is considred more applicable in clinical evaluation.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1996년도 춘계학술발표회논문집(2)
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• pp.669-674
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• 1996

The analysis for the coolability of the reactor cavity in typical Korean 1000 MWe Nuclear Unit under severe accidents is performed using MELCOR 1.8.3 code. The key parameters molten core-concrete interaction(MCCI) such as melt temperature, concrete ablation history and gas generation are investigated. Total twenty cases are selected according to ejected debris fraction and coolant mass, The ablation rate of concrete decreases as mass of the melt decreases and coolant mass increases. Heat loss from molten pool to coolant is comparable to total decay heat, so concrete ablation is delayed until water is absent and crust begins to remove. Also, overpressurization due to non-condensible gases generated during corium and concrete interacts can cause to additional risk of containment failure. It is concluded that flooded reactor cavity condition is very important to minimize the cavity ablation and pressure load by non-condensible gases on containment.

• Gut and Liver
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• 제12권6호
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• pp.633-640
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• 2018

Background/Aims: Obesity is a risk factor for gastroesophageal reflux disease (GERD), with several studies demonstrating positive associations between body mass index (BMI) and GERD symptoms. However, little is known about the effect of BMI changes on erosive esophagitis (EE). In this study, we investigated whether BMI reduction could resolve EE. Methods: A retrospective cohort study was performed to assess the natural course of EE according to changes in BMI. Participants undergoing health check-ups from 2006 to 2012 were enrolled, and 1,126 subjects with EE were included. The degree of esophagitis was measured by upper endoscopy and serially checked over a 5-year follow-up. Logistic regression and Cox proportional hazards models were used to investigate the association between BMI reduction and EE resolution. Results: Substantial weight loss is associated with EE resolution. The adjusted odds ratio for EE resolution was 1.44 (95% confidence interval [CI], 1.09 to 1.92) among participants with a decrease in BMI compared to those with no decrease in BMI. The EE resolution rate was related to the degree of BMI reduction. The effect of weight loss on EE resolution was higher among subjects who lost more weight. Compared with subjects with no decrease in BMI, the hazard ratios for EE resolution were 1.09 (95% CI, 0.89 to 1.35), 1.31 (95% CI, 1.01 to 1.72) and 2.12 (95% CI, 1.44 to 3.12) in subjects with BMI reductions of ${\leq}1$, 1-2, and >$2kg/m^2$, respectively. Conclusions: EE resolution is associated with a decrease in BMI, and weight loss is potentially an effective GERD treatment.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2005년도 학술발표회 논문집
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• pp.215-219
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• 2005

A macro spreadsheet model, WEANES (Wet Pond Annual Efficiency Simulation Model), has been developed to predict the long-term or annual removal efficiencies of wet retention/detention basins. The model uses historical, site-specific, multi-year, rainfall data, usually available from a nearby National Oceanic and Atmospheric Administration (NOAA) climatological station to estimate basin efficiencies which are calculated based on annual mass loads. Other required input parameters are: 1) watershed parameters; drainage area, pervious curve number, directly connected impervious area, and ti me of concentration, 2) pond parameters; control and overflow elevations, pond side slopes, surface areas at control elevation and pond bottom; 3) outlet structure parameters; 4) pollutant event mean concentrations; and 5) pond loss rate which is defined as the net loss due to evaporation, infiltration and water reuse. The model offers default options for parameters such as pollutant event mean concentrations and pond loss rate. The model can serve as a design, planning, and permitting tool for consulting engineers, planners and government regulators.

• 한국화재소방학회논문지
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• 제33권1호
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• pp.39-44
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• 2019

본 연구에서는 구획 화재 시 벽면을 구성하고 있는 재료 특성과 질량 유속의 상관관계를 분석하였다. 이를 위해서 내화보드와 철판 각각을 사용하여 폭 0.3 m, 높이 0.5 m 그리고 길이 3.0 m의 한 쪽 면이 밀폐된 구조물을 제작하였으며, 헵탄 풀 화재 실험을 수행하여 연소면적 $0.01m^2$과 $0.0225m^2$ 각각에 대해서 화원의 위치 변화에 따른 질량 감소율을 산출하였다. 그 결과 헵탄의 질량 유속은 연소 초기 $0.0087kg/m^2{\cdot}s$에서 내화보드 구조물의 경우 최대 $0.166kg/m^2{\cdot}s$로 증가하였으며, 철판 구조물의 경우 최대 $0.019kg/m^2{\cdot}s$ 증가하는 것으로 나타났다. 이러한 결과는 구획 공간에서 화재 확산을 보다 정확하게 예측하기 위해서는 재료의 열적 특성과 기하학적 형상을 고려하여 화재시나리오가 구성되어야 하는 것을 의미한다.

• 방재기술
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• 통권19호
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• pp.22-28
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• 1995

The rate of heat release is probably the single most important measure of fire hazard. Several tech-niques were developed for the measurement of rate of heat release, but were not suitable for fire test-ing purpose. Recently the application of oxygen consumption principle made it possible to development of well-characterized heat release rate measurement apparatus, the furniture calorimeter for large-scale fire tests and the cone calorimeter for bench-scale fire tests. The cone calorimeter can be used to determine the ignitability as well as heat release rate and smoke development, mass loss rate, combustion gas production etc. from burning materials. Thus, test method using cone calorimeter, an internationally recognized and accepted for the evalua-tion of fire properties, is a very promising tool for combustion study on various kind of materials and products.

• 한국화재소방학회논문지
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• 제22권1호
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• pp.84-92
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• 2008

본 연구에서는 영동지역의 대표 수종인 소나무와 떡갈나무를 대상으로 주요 부위별 열적특성을 고찰하고자 콘칼로리미터 시험을 수행하여 중량변화, 착화시간, 화염유지시간, 발열량 그리고 CO와 $CO_2$ 배출농도를 비교 분석하였다. 소나무와 떡갈나무 모두 가지의 총중량감소가 가장 크게 나타났으며, 낙엽의 착화시간이 9 s 정도로서 가장 빠르게 나타났다. 낙엽과 수피부위의 화염유지시간은 $640{\sim}1,016s$ 정도였으며, 총방출열량은 낙엽비 생엽의 2배 정도인 60.1 $MJ/m^2$로 가장 높게 나타났다. 또한, CO 및 $CO_2$의 최대 배출농도는 떡갈나무의 가지부위가 소나무의 가지보다 2.82배 이상 높게 나타남으로써 소나무와 떡갈나무의 열적특성은 부위별로 많은 차이가 있음을 확인하였다.

• 대한지리학회지
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• 제50권2호
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• pp.165-183
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• 2015

15세기 이래로 인간의 토지이용으로 인한 토양유실은 그 어느 때보다 급격하게 증가하였다. 그러나 '현재와 같은 토양유실이 계속되면 언제까지 토양이 유지될 수 있는가?'라는 물음에 우리는 정작 답할 수 없었다. 이는 토양생성률을 정량화하는 것이 쉽지 않았기 때문이다. 최근 우주선유발 동위원소를 이용하여 토양생성률을 정량화하는 기법이 등장하였고 국내에도 이를 적용한 시도가 있었다. 본 연구는 우주선유발 동위원소를 이용한 토양생성률 및 토양생성함수 도출 원리를 소개하고, 국내 토양생성률 연구결과를 20세기 이후의 토양유실률 자료와 비교 분석하여 토양의 지속가능기간을 예측해보았다. 대관령 고원에서 추정한 인류세 이전의 토양생성률은 평균 $0.05[mm\;yr^{-1}]$으로 밝혀졌으며, 20세기 후반 인간의 토지이용이 집약적으로 나타나는 농경지에서의 토양유실률은 이에 비해 많게는 60배나 상회하였다. 현재의 토지이용이 유지될 경우, 대하천 상류지역 농경지의 표층토양은 빠르면 수십 년내 사라질 것으로 예측된다.

• 한국터널지하공간학회 논문집
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• 제5권3호
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• pp.241-250
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• 2003

암반은 그 특성상 매우 불균질하며, 조사 및 시험을 통하여 얻을 수 있는 자료는 아주 한정적이다. 이러한 이유 때문에 암반 중에 구조물을 구축하는 작업은 많은 불확실성 (uncertainties)을 내포하게 된다. 터널 설계에 있어서 주요 설계 파라미터인 지보패턴, 굴진장 및 굴착방법 등은 최적의 값으로 결정되어야 하나 그 결정이 쉽지 않으며, 결정을 잘못할 경우 원하지 않는 risk, 즉 터널 안정성의 저하 혹은 지보재의 지나친 보강으로 인한 경제적 손실을 발생시킨다. 본 연구에서는 터널설계 시 주요한 설계 파라미터인 지보패턴 및 굴진장을 위험도 분석 기법에 근거하여 결정하는 방법을 소개하였다. 지보량이 증가할수록 신뢰지수가 증가하여 터널의 안정성이 증가함을 정량적으로 확인할 수 있었으며, 터널의 붕괴 등으로 말미암아 발생할 수 있는 손실비용 및 공사비를 고려하여 위험도 분석을 실시함으로서 최적의 지보패턴 및 굴진장을 정량적으로 결정할 수 있었다.

• 한국토양비료학회지
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• 제50권5호
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• pp.325-335
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• 2017

This study was carried out for 30 days in aeration type and agitation type reactor to characterize organic matter decomposition and ammonia volatilization during the liquid composting of pig slurry, and organic matter and nitrogen removal rate through mass balance analysis was analyzed. In the aeration type reactor, the pH increased from 7.0 to 9.13, and TS 34.5%, VS 33.4%, $BOD_5$ 71.2%, $COD_{Cr}$ 62.3% and TOC 83.2% were removed. In addition, 44.6% of TN and 65.0% of ${NH_4}^+-N$ were removed. In the agitation type reactor, the pH increased from 7.0 to 8.10, and the removal rates of TS 0.9%, VS 0.5%, $COD_{Cr}$ 27.5%, $BOD_5$ 28.9% and TOC 41.3% were obtained. And TN and ${NH_4}^+-N$ showed removal rate of 25.3% and 29.2%, respectively. The first order kinetics constant related to $BOD_5$ degradation was $-0.039day^{-1}$ for aerobic liquid composting and $-0.013day^{-1}$ for agitated reactor. Nitrogen loss in aerobic liquid composting was about 2.3 times higher than that of agitated reactor, whereas FAN/TAN in aerobic liquid composting was about 7.9 times higher than that of agitation type reactor. Therefore, despite the low FAN/TAN in the agitation type reactor, the nitrogen loss rate was relatively high.