• 한국안전학회지
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• 제29권4호
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• pp.184-190
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• 2014

Decommissioning process of nuclear facilities consist of a sequence of problem solving activities, because there may exist not only working environments contaminated by radiological exposure but also industrial hazards such as fire, explosions, toxic materials, and electrical and physical hazards. Therefore, not a few countries in the world have been trying to develop appropriate counter techniques in order to guarantee safety and efficiency of the process. In spite of that, there still exists neither domestic nor international standard. Unfortunately, however, there are few workers who experienced decommissioning operations a lot in the past. As a solution, it is quite necessary to utilize experts' opinions for risk assessment in decommissioning process. As for an individual hazard factor, risk assessment techniques are getting known to industrial workers with advance of safety technology, but the way how to integrate those results is not yet. This paper aimed to find out an appropriate technique to integrate individual risk assessment results from the viewpoint of experts. Thus, on one hand the whole risk assessment activity for decommissioning operations was modeled as a sequence of individual risk assessment steps which can be classified into two activities, decontamination and dismantling, and on the other, a risk assessment structure was introduced. The whole model was inferred with Fuzzy theory and techniques, and a numerical example was appended for comprehension.

• 한국방재안전학회논문집
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• 제10권2호
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• pp.35-41
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• 2017

최근 소화약제 취급 관련 중독사고가 다발하고 있다. 산업이 발전하고 건물이 고층화됨에 따라 다양한 소화약제가 개발되고 있으며, 이에 따라 소화약제의 안전한 사용의 문제가 중요하게 대두되고 있다. 본 연구에서는 소화약제(HCFC-123, HFC-125)에 대한 화학물질 위험성평가를 안전보건공단에서 개발한 CHARM기법을 통해 실시해보았고, 의미 있는 결과를 얻을 수 있었다. 동 연구 자료가 향후 화학물질 안전관리 체계수립에 도움이 될 수 있기를 바란다.

• ETRI Journal
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• 제41권1호
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• pp.84-92
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• 2019

Recent advances in digital holography in the far-infrared region of the spectrum have demonstrated the potential use of digital holography in homeland security as a tool to observe hostile environments in which smoke, flames, and dust impair vision. However, to make this application practical, it is necessary to simplify the optical setup. Here, we show an off-axis, self-reference scheme that spills the reference beam out from the object beam itself and avoids the need for a complex interferometric arrangement. We demonstrate that this scheme allows the reconstruction of high-quality holograms of objects captured under visible as well as far-infrared light exposure. This could pave the way to the industrialization of holographic systems to enable users to see through fire. Moreover, the quantitative nature of the holographic signal is preserved. Thus, the reported results demonstrate the possibility to use this setup for optical metrology.

• Korean Journal of Otorhinolaryngology-Head and Neck Surgery
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• 제61권12호
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• pp.637-643
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• 2018

Radioimmunotherapy (RIT) is a therapy that takes advantage of the "cross-fire" effect of emitted radiation by radionuclides conjugated to tumor-directed monoclonal antibodies (mAb) (including those fragments) or peptides. While RIT has been successfully employed for the treatment of lymphoma, mostly with radiolabeled antibodies against CD20 [$^{90}yttrium$ ($^{90}Y$)-ibritumomab tiuxetan; $Zevalin^{(R)}$ and $^{131}iodine$ ($^{131}I)-tositumomab$; $Bexxar^{(R)}$], its use in solid tumors is more challenging, so far. Immuno-PET, a tool for tracking and quantification of mAbs with PET in vivo, is an exciting novel option to improve diagnostic imaging and guide mAb-based therapy. RIT in solid tumors including head and neck cancer may be an alternative treatment with advances in various biological, chemical, and treatment procedures, and it may help to reduce unnecessary exposure and enhance the therapeutic efficacy. Also, immuno-PET based on RIT might play an important role in cancer staging, in patients or targets selection of targeted therapeutics and in monitoring the response of targeted therapeutics as precision medicine. In this review, fundamentals of RIT/immune-PET and current knowledge of the preclinical/clinical trials in RIT for solid tumor including head and neck cancer are reviewed.

• Steel and Composite Structures
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• 제41권5호
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• pp.731-746
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• 2021

The purpose of this paper is to investigate the axial bearing capacity and residual properties of steel reinforced recycled aggregate concrete (SRC) column after elevated temperature. A total of 48 SRC columns were designed for the static loading test after elevated temperature. The variables include replacement ratios, designed temperature, target duration, thicknesses of cover concrete, steel ratios and stirrup spacing. From this test, the mass loss ratio and stress load-deformation curve were obtained, and the influence of various parameters on residual bearing capacity were analyzed. ABAQUS was used to calculate the temperature field of specimens, and then got temperature damage distribution on the cross-section concrete. It was shown that increasing of the elevated temperatures leaded to the change of concrete color from smoky-gray to grayish brown and results in reducing the bearing capacity of SRC columns. The axial damage and mechanism of SRC columns were similar to those of reinforced natural aggregate concrete columns at the same temperatures. Finally, the calculation method of axial compressive residual bearing capacity of SRC columns recycled concrete columns after high temperature was reported based on the test results and finite element analysis.

• Advances in concrete construction
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• 제16권1호
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• pp.1-20
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• 2023

This study presents the experimental results performed to evaluate the effects of Polyvinyl-alcohol (PVA) and Polypropylene (PP) fibers on the fresh and residual mechanical properties of the hybrid fiber reinforced SCC before and after the exposure of 250℃, 500℃ and 750℃ temperatures. The compressive and splitting tensile strength, modulus of rupture (MOR), ultrasonic pulse velocity (UPV) as well as toughness and weight loss were investigated at different temperatures. PVA and PP fibers were added into SCC mixtures having only macro steel fiber and also having binary hybridization of both macro and micro steel fiber. The results showed that the use of micro steel fiber replaced by macro steel fiber improved the fresh and hardened properties compared to the use of only macro steel fiber. Moreover, it was emphasized that PVA or PP enhanced the residual flexural performance of SCC, generally, while it negatively influenced the workability, weight loss, UPV and the residual strengths with regards to the use of single steel fiber and binary steel fiber hybridization. Compared to the effect of synthetic fibers, PP had slightly more positive effect in the view of workability while PVA enhanced the residual mechanical properties more.

• 한국재난정보학회 논문집
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• 제9권4호
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• pp.449-461
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• 2013

최근 발생한 경북 구미의 불산 누출 및 경남 울산의 염산 누출사고의 예와 같이 화학공장에서 발생되는 사고중대 부분은 저장탱크나 운송배관 및 플랜지호스 등의 손상에 의한 휘발성 유독성물질의 대량누출이며, 이 경우 누출된 지역의 자연환경과 대기 조건에 따른 유독성물질의 확산 거동이 인적, 물적 피해의 중요한 변수가 되기 때문에 위험성평가는 가장 중요한 관심 대상이 된다. 따라서 본 연구에서는 누출물질에 대한 대기 중 확산을 모사하기 위하여 불산 저장탱크에서 누출된 경우를 예제로 선택하여, 수치해석과 ALOHA(Areal Location of Hazardous Atmospheres)의 확산 시뮬레이션을 이용한 결과해석을 수행하였다. 먼저 공정위험분석으로 정성적 평가인 HAZOP(Hazard Operability) 결과를 살펴보면 첫째 공정흐름상(flow) 위험 요소로서 플렌지, 밸브와 호스의 균열 등 손상으로 인한 누출에 의한 운전지연 또는 독성가스누출 등이 발생할 수 있고, 둘째 온도, 압력, 부식으로부터는 화재, 질소공급과 압 그리고 탱크나 파이프 이음관의 내부 부식으로 인한 독성누출의 가능성이 높은 것으로 분석되었다. 다음 결과 영향분석 기법인 ALOHA를 운용한 결과를 살펴보면 Dense Gas Model에 대한 입력 자료값에 따라 미치는 결과 영향이 다소 차이가 있음을 발견하였으나 기상조건으로서 대기안정도 보다는 풍향 및 풍속이 가장 영향을 미치는 것으로 분석 되었다. 또한 풍속이 빠를수록 누출물질의 확산이 잘 일어났고, 수치해석결과인$LC_{50}$과 ALOHA의 AEGL-3(Acute Exposure Guidline Level)과 결과를 비교했을 때 확산길이는 다소 차이가 있지만 확산농도 측면에서는 액체와 증기누출인 경우에 있어서 거의 비슷한 결과를 보였다. 따라서 ALOHA 모델을 운영한 결과 각 시나리오별 경향은 상당히 일치함을 볼 수 있었다. 따라서 추후 수치해석과 확산모델링에 의한 예측농도를 국제적인 기준치인 IDLH(Immediately Dangerous to Life and Health), ERPG(Emergency Response Planning Guideline), AEGL(Acute Exposure Guidline Level)과 비교 함 으로서 독성 가스의 대한 완충거리를 결정 할 수 있고, 이와 같은 연구방법은 유독성물질 누출에 따른 위험성평가를 보다 효율적으로 수행하는데 도움을 줄 것이며, 지역사회 비상대응체계 수립 시 적절하게 활용할 수 있을 것이다.

• 한국산업보건학회지
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• 제24권2호
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• pp.122-129
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• 2014

Objectives: Because of its properties such as resistance to heat, chemicals and corrosion; tensile strength; sound absorption; and affordable price, asbestos has been widely used as a building material, fire resistant and retardant, thermal and heat insulator, soundproofing material, and electrical insulation. Since the prolonged inhalation of asbestos can cause serious illnesses such as lung cancer, mesothelioma, and asbestosis after an incubation period of 20 to 40 years, the mineral was classified as a Group 1 carcinogen by the International Agency for Research on Cancer, an intergovernmental agency forming part of the World Health Organization. Children and infants are more at risk than are adults if they are exposed to carcinogens, due to aweaker immunity that has not yet been fully developed. Most childcare centers are operated all day and children tend to spend a great amount of time in the centers. This is why it is important for them to be systematically isolated from environments that may expose them to asbestos. Materials: In order to understand both indoor and outdoor hazards to which children may have been exposed, the study focused on actual surveys of asbestos used in childcare centers, paying special attention to slate-roofed buildings in the vicinity of the centers. Results: A survey of a total of 211 childcare centers showed that the buildings of 18.1% of the centers contained asbestos, with 60.53% of the material being found in classroom ceilings. "Tex" was the most used material for ceilings, making up 89.47% of all ceilings. An outdoor survey showed that childcare centers in Daegu Metropolitan City had an average of 143 slate-roof buildings within a distance of 1km. Conclusions: Buildings housing mainly toddlers, children, teenagers and others more vulnerable to the toxicity of asbestos are not subject to asbestos investigation by law. A legal and practical basis for asbestos control is required for such buildings. In particular, housing materials which contain asbestos in day care centers require asbestos control. GIS should be used to identify the location of buildings with slate roofing materials in the vicinity of daycare centers in order to gauge toxicity of exposure to asbestos caused by potential asbestos friability possibility in outdoor conditions.

• 한국산업보건학회지
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• 제16권3호
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• pp.233-244
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• 2006

Of many volatile organic detergents for metals, benzine(CAS No. 8030-30-6), of which the toxicity has not yet been proven, has been used as an alternative of the halide compounds in the consideration of toxic effects, global warming and the destruction of ozone layer. In order to evaluate the effects of the benzine on human body by investigating the subchronic inhalation toxicity, to obtain the basic data for establishing the criteria of exposure in working environments and to classify the hazardousness in compliance with the Industrial Safety and Health Act by evaluating the hazardousness, repeated inhalation exposure test was carried with SD rats. The rats were grouped by 10 females and males each. The repetitive inhalation exposures were carried out at 4 levels of concentration of 0 ppm, 60 ppm, 300 ppm, and 1,500 ppm, for 6 hours a day, 5 days a week, for 13 weeks. The results are described hereunder. 1. No death of the animals of the exposed and controlled groups in the test period. Not any specific clinical symptoms, change in feed intake quantity, abnormality in eye test, or change in activity were observed. 2. In the 300 ppm and 1,500 ppm groups, weight reduction in the female groups and weight increase of liver and kidney in the male groups compared with control group were observed with statistical significance(p<0.05). 3. In the blood test, the HCT increased in the male 300 ppm group and the number of hematocyte increased, MCV and MCH decreased in the male 1,500 ppm group. In the female 1,500 ppm group, the HB decreased and the distribution width of the hematocyte particle size increased. In the blood biochemistry test, the TP in the male 1,500 ppm group and the LDH in the female 1,500 ppm group were increased with statistical significance(p<0.05). 4. Under the test conditions of the present study with SD rats, the NOEL was evaluated to be from 60 ppm to 300 ppm for both male and female groups. By extrapolation, the NOEL for human who work 8 hours a day was evaluated to be from 128 ppm to 640 ppm 5. Since the NOEL evaluated in this study do not exceed 60ppm(0.184 mg/L) the test material does not belong to the classification of the hazardous substance "NOEL${\leq}$0.5mg/L/6hr/90day(rat), for continuous inhalation of 6hours a day for 90 days" nor to the basic hazardous chemical substance class 1(0.2 mg/L/6hr/90day(rat) defined by the GHS which is a criteria of classification and identification of chemical compounds. However, considering the boiling point($30-204^{\circ}C$), flashing point($-40^{\circ}C$), vapor pressure(40 mmHg), and the inflammable range(1.0 - 6.0 %), sufficient care should be taken for handling in the safety aspects including fire or explosion.

• 국제초고층학회논문집
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• 제10권4호
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• pp.335-344
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• 2021

In structural engineering practice, understanding the performance of composite columns under extreme loading conditions such as high-rise bulding, long span and heavy loads is essential to accuratly predicting of material responses under severe loads such as fires or earthquakes. Hitherto, the combined effect of partial axial loads and subsequent elevated temperatures on the performance of hollow steel column filled fly ash concrete have not been widely investigated. Comprehensive test was carried out to investigate the effect of elevated temperatures on partial axially loaded square hollow steel column filled fly ash concrete as reported in this paper. Four batches of hollow steel column filled fly ash concrete ( 30 percent replacement of fly ash), (HySC) and normal concrete (CFHS) were subjected to four different load levels, n_f of 20%, 30%, 40% and 50% based on ultimate column strength. Subsequently, all batches of the partially damage composite columns were exposed to transient elevated temperature up to 250℃, 450℃ and 650℃ for one hour. The overall stress - strain relationship for both types of composited columns with different concrete fillers were presented for each different partial load levels and elevated temperature exposure. Results show that CFHS column has better performance than HySC at ambient temperature with 1.03 relative difference. However, the residual ultimate compressive strength of HySC subjected to partial axial load and elevated temperature exposure present an improvement compared to CFHS column with percentage difference in range 1.9% to 18.3%. Most of HySC and CFHS column specimens failed due to local buckling at the top and middle section of the column caused by concrete crushing. The columns failed due to global buckling after prolong compression load. After the compression load was lengthened, the columns were found to fail due to global buckling except for HySC02.