• 한국재료학회지
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• 제20권3호
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• pp.148-154
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• 2010

It is necessary to develop new methods to prevent catastrophic failure of structural material in order to avoid accidents and conserve natural and energy resources. Design of intelligent materials with a self-diagnosing function to prevent fatal fracture of structural materials was achieved by smart composites consisting of carbon fiber tows or carbon powders with a small value of ultimate elongation and glass fiber tows with a large value of ultimate elongation. The changes in electrical resistance of CF-GFRP/GFRP (carbon fiber and glass fiber-reinforced plastics/glass fiber-reinforced plastics) composites increased abruptly with increasing strain, and a tremendous change was seen at the transition point where carbon fiber tows were broken. Therefore, the composites were not to monitor damage from the early stage. On the other hand, the change in electrical resistance of CP-GFRP/GFRP (carbon powder dispersed in glass fiber-reinforced plastics/glass fiber-reinforced plastics) composites increased almost linearly in proportion to strain. CP-GFRP/GFRP composites are superior to CF-GFRP/GFRP composites in terms of their capability to monitor damage by measuring change in electrical resistance from the early stage of damage. However, the former was inferior to the latter as an application because of the difficulties of mass production and high cost. A method based on monitoring damage by measuring changes in the electrical resistance of structural materials is promising for improved reliability of the material.

• 한국산업융합학회 논문집
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• 제23권4_2호
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• pp.637-644
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• 2020

Because suicide accidents sometimes were happened in grand bridges over rivers or sea water recently, it will be necessary that prevention measures be made preparation in advance from now on. Additional safety facilities must be needed in addition to existing safety facilities in such a way as this prevention measure. In order to make cable-stayed bridge safe on wind for additional safety facilities, main girder models with added safety facilities for wind-tunnel tests was made, and wind tunnel experiments was carried out to measure aerodynamic force coefficients. Also, wind-resistant analyses of 3D cable-stayed bridge were performed on the basis of wind-tunnel test results. From the wind experiments, force coefficients of main girder with added safety facilities were assessed, and it is known that there are little possibility of galloping and rotation of steel main girder. Finally, from the wind resistant analyses, it was concluded that wind-resistant safety of cable-stayed bridge was secured on wind speed 60.6m/sec.

• 방사선산업학회지
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• 제9권3호
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• pp.127-130
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• 2015

Since the accident at the Fukushima Daiichi power plant, Prussian blue (PB) has attracted increasing attention as a material for use in decontaminating the environment. We have focused the fundamental mechanism of specific $Cs^+$ adsorption into PB in order to develop high-performance PB-based $Cs^+$ adsorbents. The ability of PB to adsorb Cs varies considerably according to its origin such as what synthesis method was used, and under what conditions the PB was prepared. It has been commonly accepted that the exclusive abilities of PB to adsorb hydrated $Cs^+$ ions are caused by regular lattice spaces surrounded by cyanido-bridged metals. $Cs^+$ ions are trapped by simple physical adsorption in the regular lattice spaces of PB. $Cs^+$ ions are exclusively trapped by chemical adsorption via the hydrophilic lattice defect sites with proton-exchange from the coordination water. Prussian blue are believed to hold great promise for the clean-up of $^{137}Cs$ contaminated water around nuclear facilities and/or after nuclear accidents.

• Advances in Computational Design
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• 제4권2호
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• pp.91-118
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• 2019

Every year, many people are severely injured or lose their lives in accidents such as fire, chemical spill, public pandemonium, school shooting, and workplace violence. Research indicates that the fate of people in an emergency situation involving one or more hazards depends not only on the design of the space (e.g., residential building, industrial facility, shopping mall, sports stadium, school, concert hall) in which the incident occurs, but also on a host of other factors including but not limited to (a) occupants' characteristics, (b) level of familiarity with and cognition of the surroundings, and (c) effectiveness of hazard intervention systems. In this paper, we present EVAQ, a simulation framework for modeling large crowd evacuation by taking into account occupants' behaviors and interactions during an emergency. In particular, human's personal (i.e., age, gender, disability) and interpersonal (i.e., group behavior and interactions) attributes are parameterized in a hazard-impacted environment. In addition, different hazard types (e.g., fire, lone wolf attacker) and propagation patterns, as well as intervention schemes (simulating building repellent systems, firefighters, law enforcement) are modeled. Next, the application of EVAQ to crowd egress planning in an airport terminal under human attack, and a shopping mall in fire emergency are presented and results are discussed. Finally, a validation test is performed using real world data from a past building fire incident to assess the reliability and integrity of EVAQ in comparison with existing evacuation modeling tools.

• Nuclear Engineering and Technology
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• 제52권12호
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• pp.2836-2846
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• 2020

During severe nuclear power plant (NPP) accidents, a H₂/CO mixture can be generated in the reactor pressure vessel by core degradation and in the containment as well by molten corium-concrete interaction. In spite of its importance, a state-of-the-art methodology predicting H₂/CO combustion risk relies predominantly on empirical correlations. It is therefore necessary to develop a proper methodology for flammability evaluation of H₂/CO mixtures at ex-vessel phases characterized by three factors: CO concentration, high temperature, and diluents. The developed methodology adopted Le Chatelier's law and a calculated non-adiabatic flame temperature model. The methodology allows the consideration of the individual effect of the heat transfer characteristics of hydrogen and carbon monoxide on low flammability limit prediction. The accuracy of the developed model was verified using experimental data relevant to ex-vessel phase conditions. With the developed model, the prediction accuracy was improved substantially such that the maximum relative prediction error was approximately 25% while the existing methodology showed a 76% error. The developed methodology is expected to be applicable for flammability evaluation in chemical as well as NPP industries.

• Nuclear Engineering and Technology
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• 제55권7호
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• pp.2504-2515
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• 2023

In past years the Paul Scherrer Institute (PSI, Switzerland) and the Karlsruhe Institue of Technology (KIT, Germany)) collaborated to develop a model to account for the active role of nitrogen in the air oxidation of a Zircalloy cladding. The "PSI-KIT Nitriding Model for Zirconium based Fuel Cladding" model was implemented at PSI into PSI-MELCOR 1.8.6. In order to make a preliminary evaluation of the effect of the new model on the evolution of full-scale spent fuel pool accidents, one spent fuel pool event was analyzed using the PSI research version of PSI-MELCOR 1.8.6, which includes the nitriding model. To adapt an existing input deck for the calculations, a sensitivity study was conducted to find an optimal nodalization for the analyses. The nitriding model results were compared to those calculated with the MELCOR 1.8.6-PSI without the new nitriding model. The results demonstrate the effect of the nitriding reactions in spent fuel pool accident progression. Moreover, they confirm the impact of ZrN formation during cladding oxidation in air when the oxidation reactions lead to oxygen starvation inside the fuel assemblies. The nitriding reaction led to higher chemical heat generation during the accident and to an earlier failure of the cladding than when the effect of nitrogen reactions was not considered. It should be noted that the nitriding model, as implemented in the PSI version of MELCOR 1.8.6 has not yet been conclusively validated. Thereby the results presented in this paper should be treated as a preliminary demonstration of the capabilities of the model.

• 한국수소및신에너지학회논문집
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• 제34권3호
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• pp.297-306
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• 2023

The frequency of fatal accidents that can occur at hydrogen refueling station was compared with the risk criterion for the general public suggested by the health and safety executive. If hydrogen refueling station meets the accident prevention facility standards presented in KGS Code FP216/217, it was confirmed that the risk of hydrogen refueling station was not at an unacceptable (intolerable) risk level. However, the risk of hydrogen refueling station due to small leak was analyzed as low as reasonably practicable. Therefore, methods for improving the safety instrumented function of hydrogen refueling station were reviewed. It was confirmed that the risk of hydrogen refueling station can be affected by the number of installed safety instrumentation system components, redundant architecture, mission time, proof test interval, etc. And methods for maintaining the risk of hydrogen refueling station at an acceptable risk level have been proposed.

• Journal of Nutrition and Health
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• 제50권4호
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• pp.402-414
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• 2017

본 연구는 전북지역 산업체급식소의 정규직과 비정규직 조리종사자 282명을 대상으로 급식소에서의 안전사고, 안전교육 실태 및 안전사고 예방관리의 중요도 및 수행도를 조사하여 산업체급식소의 안전사고 예방을 위한 효율적인 관리방안을 제시하고자 하였으며, 그 결과를 요약하면 다음과 같다. 조사대상자는 정규직 42.2% (119명), 비정규직 57.8% (163명) 이며 96.5%는 여자이었다. 고용형태에 따라서는 연봉수준 (p < 0.001), 직급 (p < 0.001), 평균 연령 (p < 0.001), 급식횟수 (p < 0.001)에서 유의적인 차이를 보였다. 정규직의 66.4%, 비정규직의 53.4%가 안전사고의 경험이 있으며 (p < 0.05), 사고원인은 본인의 부주의 (53.5%)가 가장 큰 원인이었다. 사고처리는 정규직은 회사부담 (71.6%)이 높으며 비정규직은 산재처리 (44.6%)가 높았다. 안전사고는 정규직은 화상 (48.6%), 절단사고 (31.1%)가 높았으며 비정규직은 미끄러짐 (47.8%)과 화상 (44.6%)의 순으로 차이가 있었다. 사고부위는 주로 손과 팔 (63.3%) 이었다. 정규직의 98.3%, 비정규직의 95.1%가 안전사고 예방을 위한 안전교육을 받았으며, 교육은 주로 영양사 (93.4%)가 실시하나 정규직은 산업안전관리공단 (6.8%)과 협회(2.6%)의 교육도 받고 있었다. 교육 빈도는 정규직의 68.4%가 1회, 23.9%가 2회, 7.7%는 3회 이상의 교육을 받았으나 비정규직은 1회 50.3%, 2회 37.4%, 3회 이상 12,2%로 비정규직의 교육 빈도가 유의하게 높았다 (p < 0.05). 교육방법은 주로 강의 (77.2%)로 진행되며, 교육 후 정규직의 37.6%는 별도의 평가가 없으나, 비정규직의 33.5%는 시험, 25.2%는 면담, 12.3%는 실기평가를 실시하고 있었다 (p < 0.05). 교육만족도는 조사대상자의 81.6%가 만족하며 비정규직 (85.2%)이 정규직 (76.9%)보다 더 만족하는 경향을 보였다. 교육 후 정규직의 73.5%, 비정규직의 71.6%만이 실제 작업에 교육내용을 적용하고 있었다. 적용하지 못하는 이유는 업무과중으로 인한 시간부족과 습관적인 작업행태 때문이었다. 산업체급식소의 정규직과 비정규직 조리종사원의 안전사고 예방관리에 대한 정규직과 비정규직의 중요도는 각각 4.26점, 4.15점이며 수행도는 정규직 3.96점, 비정규직 3.94점이었다. 독립표본 t-test로 분석한 결과, 21개의 항목 중 '튀김요리 시 물이 튀지 않게 하며 화상에 주의한다'에서 정규직 (4.43점)이 비정규직 (4.24점)보다 중요도가 유의적으로 높았으나 (p < 0.05), 수행도는 모든 항목에서 정규직과 비정규직간 유의적인 차이는 없었다. 대응표본 t-test 분석결과, 정규직의 중요도와 수행도간의 유의적인 차이를 보였다 (p < 0.001). 전체 21개 항목의 중요도와 수행도간에 유의적인 차이를 보였다. IPA분석결과, 중요도와 수행도가 높은 A영역 (Doing great)에서 '작업장 바닥의 물, 기름을 청소', '작업장과 통로의 물건 정리', '작업 시 미끄럼방지 안전화 착용', '사용하지 않는 호스는 감아서 정리', '화재위험 있는 전열기 코드 뽑기', '튀김요리 시 화상에 주의하며 조리'는 정규직과 비정규직 모두 해당되었으며, 이외 '물기 있는 손으로 전기시설 관리하지 않기'는 정규직에만 해당되었으며 '야채절단기 사용 시전용방망이 사용', '안전하게 칼 관리'는 비정규직에만 포함되었다. 중요도가 높으나 수행도가 낮은 B영역 (Focus here)에서 '출근 후 환기와 가스누출 확인', '콘센트 안전관리'는 정규직과 비정규직 모두 해당되었으며 이외에 '영양사에게 건강상태 보고' 및 '중량물 취급 시 올바른 자세로 작업'은 정규직에만 '가스차단기 작동확인'은 비정규직에만 포함되었다. 중요도는 낮으나 수행도가 높은 C영역(Overdone)에서 '기계설비 잠금장치 확인'은 정규직과 비정규직 모두에 해당되었으며 이외에 '야채절단기 사용 시 전용방망이 사용', '안전하게 칼 관리'는 정규직에 포함되었으며 '물기 있는 손으로 전기시설 관리하지 않기', '전기기구 연결 확인', '영양사에게 건강상태 보고' 및 '중량물 취급 시 올바른 자세로 작업'은 비정규직에 포함되었다. 중요도와 수행도가 낮은 D영역 (Low priority)에 'MSDS관리', '화학물질 위험표시 인지', '화학물질 취급 전 보호 장갑 등의 장비 착용', '작업 전 스트레칭 실시' 및 '보조도구를 이용하여 안전하게 작업대 높이 조정'이 정규직과 비정규직에 포함되었으며 이외에 정규직에 '전기기구 연결 확인', '가스차단기 작동확인'이 추가되었다. 본 연구결과를 종합하면, 전북지역 산업체급식소에서의 안전교육 실시는 잘 진행되고 있으나 아직도 교육을 받지 못하는 비정규직이 있으므로 이에 대한 경영주 및 영양사의 인식전환이 필요하겠다. 또한 조리종사원들의 안전사고 예방관리에 대한 중요도 인식은 고용형태 간 유의적인 차이 없이 높은 수준이었으나 교육 후 업무과중의 이유로 실제 적용하는 어려움이 있는 점을 볼 때 효율적인 업무관리 및 안전사고 예방을 위한 철저한 감독이 요구된다. 특히, 화학물질에 대한 이해 및 MSDS관리에 대한 조리종사원들의 낮은 중요도 인식과 수행도는 향후 안전교육에서 중요하게 다루어야 하겠다. 향후 정규직과 비정규직 구분에 따른 지원의 차이를 줄이고 소속감을 높여 조리종사원의 책임감과 안전의식을 높여 보다 안전한 급식소환경이 될 수 있는 방안이 요구된다.

• 한국환경보건학회지
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• 제41권1호
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• pp.1-10
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• 2015

Objectives: The purpose of this study was to propose an indirect exposure assessment method using a questionnaire survey at a time when direct exposure assessment would be impossible after a chemical accident. Methods: About two weeks after an accident, a questionnaire survey was performed with 1,264 persons from the local community. Variables related to exposure were extracted from the survey contents, weighted and then graded for comparison with subjective symptoms in order to evaluate the extent of exposure. Survey items suitable for reflecting the previous exposure level during the accident were extracted, weighted and divided into quartile ranges. Subjective symptoms showed an increasing tendency with higher exposure level when compared with final exposure level (p<0.01). Results: For the relationship between the final exposure grade and subjective symptoms, as the exposure grade was increasing the rates complaining of symptom also showed an increasing tendency. However, when adjusted for demographic characteristics, there was a tendency for the eye irritation symptom to appear higher in women, and respiratory organ irritation appeared higher in smokers. Conclusions: When the problem of recall bias is considered, this study may not have completely unraveled exposure and the characteristics of the participants can affect subjective symptoms. Nevertheless, the exposure rating method of using a questionnaire showed a significant relationship with symptom level. It can be deemed that assessment of past exposure may be successfully evaluated by questionnaire in cases such as chemical accidents.

• 한국대기환경학회지
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• 제19권5호
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• pp.595-610
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• 2003

The statistical indexes such as RMSE (Root Mean Square Error), Mean Bias error, and IOA (Index of agreement) are used to evaluate 3 Dimensional wind and temperature fields predicted by operational meteorological model RAMS (Regional Atmospheric Meteorological System) implemented in CARIS (Chemical Accident Response Information System) for the dispersion forecast of hazardous chemicals in case of the chemical accidents in Korea. The operational atmospheric model, RAMS in CARIS are designed to use GDAPS, GTS, and AWS meteorological data obtained from KMA (Korean Meteorological Administration) for the generation of 3-dimensional initial meteorological fields. The predicted meteorological variables such as wind speed, wind direction, temperature, and precipitation amount, during 19 ∼ 23, August 2002, are extracted at the nearest grid point to the meteorological monitoring sites, and validated against the observations located over the Korean peninsula. The results show that Mean bias and Root Mean Square Error are 0.9 (m/s), 1.85 (m/s) for wind speed at 10 m above the ground, respectively, and 1.45 ($^{\circ}C$), 2.82 ($^{\circ}C$) for surface temperature. Of particular interest is the distribution of forecasting error predicted by RAMS with respect to the altitude; relatively smaller error is found in the near-surface atmosphere for wind and temperature fields, while it grows larger as the altitude increases. Overall, some of the overpredictions in comparisons with the observations are detected for wind and temperature fields, whereas relatively small errors are found in the near-surface atmosphere. This discrepancies are partly attributed to the oversimplified spacing of soil, soil contents and initial temperature fields, suggesting some improvement could probably be gained if the sub-grid scale nature of moisture and temperature fields was taken into account. However, IOA values for the wind field (0.62) as well as temperature field (0.78) is greater than the 'good' value criteria (> 0.5) implied by other studies. The good value of IOA along with relatively small wind field error in the near surface atmosphere implies that, on the basis of current meteorological data for initial fields, RAMS has good potentials to be used as a operational meteorological model in predicting the urban or local scale 3-dimensional wind fields for the dispersion forecast in association with hazardous chemical releases in Korea.