• 한국태양에너지학회 논문집
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• 제35권3호
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• pp.65-71
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• 2015

A solar thermal simulator is suitable for indoor experiments of solar receivers and reactors when solar insolation and weather conditions are not favorable. Moreover, due to the easy control of electric power input, the solar thermal simulator allows the adjustment of power input incident on solar receivers and reactors and thus the implementation of accurate experiments. We manufactured a solar simulator, which is comprised of three sets of a xenon lamp and an elliptical reflector. In order to serve as a test facility, optical characterization of the solar simulator via radiation heat flux measurement is a critical prerequisite. We applied the flux mapping method to measuring the heat flux distribution of the three lamps. We presented the measurement results in terms of the heat flux distribution, the peak heat flux, the power distribution, the maximum power, and the efficiency for electric power conversion into radiation power. Characterization results show that our solar simulator provides the peak heat flux of $3,019kW/m^2$, the maximum power of 16.9 kW, and the conversion efficiency of 45%, additionally with a 10% operation margin for output increase.

• 대한방사선기술학회지:방사선기술과학
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• 제42권1호
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• pp.1-7
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• 2019

In order to analyze the factors affecting incidence angle and incident point when conducting a general radiography using Sella Turcica, the length and width of the head bone according to age and gender, length and width of Sella Turcica, and the distance between the front and the top of EAM to Sella Turcica were measured. The subjects were 400 patients who underwent a Skull series. For statistical analysis, t-test and ANOVA analysis were conducted using SPSS Ver.22.0. For post-test, Duncan was conducted and if the results were 95% or more (p<.05), it was determined to be significant. As a result of this study, the average length of the head bone was 177.45 mm, where the males were 182.84 mm and the females were 172.05mm showing that males were measured longer (p<.001). The width of the head bone was 116.98mm on average, where the males were 119.18mm and the females were 114.77mm(p<.001) showing that males were measured longer. The average length of Sella Turcica was 4.59mm, where the males were 4.54mm(p<.001) and the females were 4.63mm(p<.001) showing that females were measured longer. The average length of Sella Turcica was 7.08mm, where the males were 7.01mm(p<.001) and the females were 7.16mm(p<.001) showing that females were measured longer. The general radiology examination of Sella Turcica at a medical facility should be conducted in consideration of age and gender in accordance with the characteristics of Koreans.

• 스마트미디어저널
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• 제11권5호
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• pp.56-62
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• 2022

배수지는 정수처리 된 물을 급수하기 위해 정수물을 모아두는 저장소로서, 물의 수요량에 따라 급수량을 조절하여 안정적으로 물을 공급하기 위해 배수지의 수위 관리는 매우 중요하다. 현재 배수지 내에 수위 계측 센서를 설치하여, 가압장의 펌프운영을 통해 배수지의 최적 수위를 관리하고 있으나, 센서의 오작동 및 통신두절 등 사고대응을 관리자 감시에 의존하고 있어, 사고의 위험을 안고 있다. 본 연구에서는 배수시설의 안정적 운영을 위하여, 배수지의 수위 변화 예측 인공지능 모델을 제안하였으며, 배수지 수위 변화 예측모델의 현장적용에 대한 안정성을 확인하기 위하여 수위 데이터의 결측 상황에 대한 시뮬레이션을 통하여, 실제 수위 변화값과 예측된 수위 변화값의 비교를 통하여 모델의 유용성을 확인하였다.

• Nuclear Engineering and Technology
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• 제54권10호
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• pp.3855-3863
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• 2022

An evaluation of the radiation shielding performance of high-Z-particle-loaded polylactic acid (PLA) composite materials was pursued. Specimens were produced via fused deposition modeling (FDM) using copper-PLA, steel-PLA, and BaSO₄-PLA composite filaments containing 82.7, 75.2, and 44.6 wt% particulate phase contents, respectively, and were tested under broad-band flash x-ray conditions at the Sandia National Laboratories HERMES III facility. The experimental results for the mass attenuation coefficients of the composites were found to be in good agreement with GEANT4 simulations carried out using the same exposure conditions and an atomistic mixture as a model for the composite materials. Further simulation studies, focusing on the Cu-PLA composite system, were used to explore a shield design parameter space (in this case, defined by Cu-particle loading and shield areal density) to assess performance under both high-energy photon and electron fluxes over an incident energy range of 0.5-15 MeV. Based on these results, a method is proposed that can assist in the visualization and isolation of shield parameter coordinate sets that optimize performance under targeted radiation characteristics (type, energy). For electron flux shielding, an empirical relationship was found between areal density (AD), electron energy (E), composition and performance. In cases where ${\frac{E}{AD}}{\geq}2MeV{\bullet}cm{\bullet}g^{-1}$, a shield composed of >85 wt% Cu results in optimal performance. In contrast, a shield composed of <10 wt% Cu is anticipated to perform best against electron irradiation when ${\frac{E}{AD}}<2MeV{\bullet}cm{\bullet}g^{-1}$.

• Architectural research
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• 제24권4호
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• pp.105-111
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• 2022

During pandemic period, college students lost lots of such academic opportunities as extra-curriculum social activities, contact classes, and friendly socializing in university campus area, etc. Previous many studies have shown that physical environment has certain relevance on the well-being of human-beings. Recent public statistics on mental health had shown an increase in psychological distress and a decrease in college students and people's well-being during the lockdown in response to the Covid-19 pandemic. However, there were little evidence on what the college students in dormitory suffered from COVID-19 incident in relation with their physical environment. The purpose of this study is to investigate the relationship between environmental factors and psychological well-being of dormitory students in university campus. In order to explore the impact of physical environment on students' psychological well-being, survey instrumentation consisted of 25 indices were employed to measure the level of awareness to each index. A Chi-square analysis on individual characteristics of 200 students found that number of students living in single dwelling unit was statistically significant to maintain their psychological well-being, except for number of students living in each dwelling unit (χ² =128.92, p= .004). Pearson correlation analysis also found that there exists statistically significant relationship between psychological well-being of students and environmental factors. Further, stepwise multiple regression analysis revealed that the most prime predictor for psychological well-being of students residing in dorm was "use of furniture" (β= .281), implying careful design, lay-out and easy-access to interior furniture by facility planner. The study also demonstrated that as the level of positive perception of physical environmental features rose, overall psychological well-being of students also responded positively at specified rate. Finally, the findings reinforce a solid evidence that carefully well-coordinated physical environments play an important role in maintaining emotional stability of college students in dorm even in pandemic period.

• 한국수소및신에너지학회논문집
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• 제35권1호
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• pp.66-74
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• 2024

This study addresses the escalating issue of worldwide hydrogen gas accidents, which has seen a significant increase in occurrences. To comprehensively evaluate the risks associated with hydrogen, a two approach was employed in this study. Firstly, a qualitative risk assessment was conducted using the bow-tie method. Secondly, a quantitative consequence analysis was carried out utilizing the areal locations of hazardous atmospheres (ALOHA) model. The study applied this method to two incidents, the hydrogen explosion accident occurred at the Muskingum River power plant in Ohio, USA, 2007 and the hydrogen storage tank explosion accident occurred at the K Technopark water electrolysis system in Korea, 2019. The results of the risk assessments revealed critical issues such as deterioration of gas pipe, human errors in incident response and the omission of important gas cleaning facility. By analyzing the cause of accidents and assessing risks quantitatively, the effective accident response plans are proposed and the effectiveness is evaluated by comparing the effective distance obtained by ALOHA simulation. Notably, the implementation of these measures led to a significant 54.5% reduction in the risk degree of potential explosions compared to the existing risk levels.

• 농촌의학ㆍ지역보건
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• 제28권1호
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• pp.15-27
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• 2003

Objectives: This study was conducted to compare the medical care patterns of hypertensive patients between rural and urban areas. Methods: We selected one rural county(Region A where there were 19 public health centers; one health center, 8 health sub-centers and 10 community health posts) and two urban districts(Region B and C where there was no health sub-center and community health post) in Daegu city. Region B had similar socioeconomic characteristics with rural county A while region C had different characteristics. The medical insurance records of 14,422 incident patients (2,501 in region A, 4,873 in region B and 7,048 in region C) with diagnostic code of hypertension from September 1998 to August 1999 were reviewed. Incident patient was defined as a patient who had no record of medical fee claim for hypertension to the national health insurance corporation in past 6 months and visited a medical facility for hypertension for the first time. The data for annual visit days, annual prescription days and annual total medical expenses were abstracted. The medical care pattern was categorized by the number of annual visit days and prescription days. The most proper care group was defined as the patient who visited 6-15 days with 240 prescription days or more in a year. Results: The type of medical facilities for the most visit was clinics, 373.% and it was followed by general hospitals, 28.2%; public health centers, 24.7%; and hospitals, 9.8% in region A(p<0.05). In region B, it was clinics, 63.1% and followed by general hospitals, 27.6%; health center, 5.2%; and hospitals, 4.1%(p<0.05). In region C, it was clinics, 53.8% and followed by general hospitals, 35.0%; health center, 6.3%; and hospitals, 4.9%(p<0.05). Annual mean total medical expenses per patient was highest in region C(won195,993) and followed by region A(won191,683) and region B(won178,713). The proportion of the most proper care group was 7.7% in region A, 5.2% in region B and 6.7% in region C(p<0.05). According to the type of medical facilities for the first visit, the proportion of the most proper care group was highest(14.7%) in the patients of public health centers, and it was followed by general hospitals, 8.8%; clinics, 3.6%; and hospitals, 2.0% in region A(p<0.05). In region B, it was highest in general hospitals, 9.7% and followed by hospitals, 4.0%; health center, 3.6%; and clinics, 3.4%(p<0.05). In region C, it was highest in general hospitals, 10.1% and followed by clinics, 5.2%; hospitals, 4.1%; and health center, 3.1%(p<0.05). Conclusions: The proportion of proper care for hypertension was higher in rural area and it was attributed to the care of health center, sub-centers and community health posts which appeared to follow patients better than hospitals and clinics.

• 한국가스학회지
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• 제16권1호
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• pp.39-45
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• 2012

천연가스 공급 시설은 가스 소비자에게 사용의 편리성과 동시에 위험성을 제공하기 때문에 매우 까다로운 위험관리 대상이다. 따라서 그 위험을 최대한 낮추면서 가스 공급을 위해서는 합리적 안전 관리 의사 결정 방법이 필요하며 정량적 위험성 평가(QRA)는 그 적합한 도구로 인식되고 있다. 하지만 수백여개에 이르는 가스 공급 시설들에 대하여 QRA 수행하는 것은 전문가 부족과 분석 시간이 오래 소요되는 문제로 인해 효과적으로 이루어지기 어렵다. 이에 본 논문에서는 가스 공급시설에 대하여 QRA를 보다 효율적으로 수행할 수 있는 시스템 체계를 제시하였다. 이 체계의 핵심적 특징은 사고점이라고 지칭한 분석점에 전문가가 사전 분석을 통해 대상 설비(들)에 대한 사고 빈도/결과 분석에 필요한 값을 얻기 위한 질의서와 내부 계산식을 만들어놓고 일반 사용자는 그 점을 지도에 위치시키고 그 내부 질의에서 요구하는 값을 입력함으로써 QRA가 수행되는 것이다. 궁극적으로 이는 QRA 분석 절차에 있어서 분업화가 가능하다는 아이디어에 기반하여 제시된 것이며 본 논문에서는 실제적 시스템 구축과 적용을 통해 그 체계의 유효성을 확인하였다.

• 대한방사선기술학회지:방사선기술과학
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• 제39권4호
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• pp.643-649
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• 2016

사이클로트론을 이용하여 $^{18}F^-$동위원소를 생산하는 경우 가속된 양성자 빔은 사이클로트론의 금속부품들과 반응하여 방사화를 일으킨다. 그 중에서도 빔과 주요하게 반응하는 표적집합체를 구성하는 표적실, 표적창에 장반감기의 핵종이 많이 발생한다. 이러한 표적집합체의 방사화 핵종을 잘 이해하는 것은 사이클로트론 운영자와 유지 보수 작업자를 위해서 매우 중요하다. 본 연구에서는 IBA(Ion Beam Application)사 사이클로트론 Cyclone 18/9 기기의 표적집합체 유지보수 작업자의 방사선 안전지침을 마련하기 위해서 사이클로트론 가동 후 표적집합체에 발생되는 주요 핵종을 분석하고, 또한, 사이클로트론 가동정지 직후부터의 선량감소율을 실험적으로 측정하였다. $^{18}F^-$동위원소 생산 후 표적집합체의 잔류 방사화 핵종의 종류 및 방사능농도를 확인하기 위하여, 표적실내 잔류물질 및 표적창 하버포일 시료를 채취하여 고순도 게르마늄(HPGe) 감마핵종분석기로 측정하여 분석하였다. 또한, 사이클로트론 가동직후 사이클로트론에서 발생되는 선량률을 시간에 따라 측정하였다. 감마핵종분석과 선량률감소에 대한 데이터는 추후 사이클로트론 운영의 방사선안전을 위한 데이터로 활용될 수 있을 것으로 기대된다.

• 한국가스학회지
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• 제21권6호
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• pp.88-95
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• 2017

국내에서 독성가스의 사용은 반도체, 디스플레이 및 태양광 등 첨단산업의 발전에 따라 증가하고 있는 추세이다. 최근 5년간 국내 독성가스 소비량 현황을 살펴보면 연평균 12% 정도 증가 추세에 있지만, 아직까지 사용에만 관심이 집중되고 있고, 사후 처리나 안전에는 다소 소홀한 것이 사실이다. 2012년 9월 발생한 구미 불산 누출사고는 이러한 안전관리 부재를 단적으로 보여주는 사례이다. 이 사고로 인하여 정부, 업계 및 학계에서는 화학물질(독성가스) 누출사고 등에 대한 관심을 갖게 되었고, 정부 주도로 화학물질안전관리대책 등이 수립되어 추진되어 왔지만 아직까지 안전관리 사각지대가 많은 실정이다. 본 연구에서는 반도체, 디스플레이 업종에서 사용되는 저감설비에서 배출되는 가스상 물질에 대한 처리효율에 대한 효과적인 측정방법을 개발하는 것이 목적이다. 국립환경과학원과 UNFCCC에서 제시하는 반도체 & 디스플레이 업종에서 사용되는 온실가스 저감시설의 처리효율 측정방법 가이드라인에 대해 실증시험을 통해 맹독성가스 시설에도 오차 범위 내에서 적용 가능한지를 살펴보고 맹독성가스 저감시설에 대한 차별화된 효율성 측정 방법을 제시하였고, 독성가스 사고에 대한 선제적 예방을 위해서 독성가스 저감시설 등 안전설비에 대한 제3자 인증제도 도입의 필요성을 제안하였다.