• Nuclear Engineering and Technology
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• 제38권5호
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• pp.449-454
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• 2006

Neutron imaging technique was used to investigate the water distribution and movement in Polymer Electrolyte Membrane Fuel Cell (PEMFC) at HANARO, KAERI. The Feasibility tests were performed in the first and second exposure rooms at the neutron radiography facility (NRF) at HANARO in order to check the ability of each exposure room, respectively. The feasibility test apparatus was composed of water and pressurized air before making up the actual test apparatus. Due to the low neutron intensity in the second exposure room, the exposure time was too long to investigate the transient phenomena of PEMFC. Although the exposure time was improved to 0.1 sec in the first exposure room, it was difficult to discriminate detail water movement at the channel due to the high noise level. Therefore, the experimental setup must be optimized according to the test conditions. Water discharge characteristics were investigated under different flow field geometries by using feasibility test apparatus and the neutron imaging technique. The water discharge characteristics of a 3-parallel serpentine are superior to those of a 1-parallel serpentine, but water at Membrane Electrode Assembly (MEA) was not removed, regardless of the flow field type.

• 한국전자파학회논문지
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• 제16권8호
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• pp.810-814
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• 2005

TEM 셀 내에 있는 혈액에 대한 삽입 손실과 반사율을 측정하여, 원하는 혈액 흡수 SAR(Specific Absorption Rate) 선택에 따른 TEM셀 입력 전력을 구하였다. 혈액 세포는 피부 세포와 함께 전자파 영향을 연구하기 위한 기준 세포이다. 따라서 SAR에 따른 혈액 세포에 인가할 전력 산출은 정확해야 함은 물론 타당성이 있어야 한다. 이 연구에서는 g당 혈액 세포가 받는 전력을 산출하기 위해 50 g의 혈액을 이용하여 전달 전력 감소를 측정하였다. 측정된 데이터로부터 휴대폰 전자파 생체 흡수율 SAR 0.8, 1.6, 3, 4 mW/g에 해당하는 TEM셀 입력 전력을 계산하였다. 이 연구 결과는 배양 세포의 전자파 방사 장치에 응용함을 목적으로 하고 있다.

• Journal of Preventive Medicine and Public Health
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• 제31권3호
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• pp.404-413
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• 1998

This study was conducted in order to clarify the factors affecting the number of utilization to health center for the shipyard workers who have been work in exposed environment to solvent. At first the tendencies of the number of utilization to health conte. in accordance with cumulative exposure(CE), lifetime weighted average exposure(LWAE), one's place of duty, work contents, states of using safety apparatus, the degree of the knowledge on handling solvents, exposure year. 1). The increase in the cumulative exposure(CE) war significantly higher in the number of utilization to health center. The group with longer exposure year showed significantly higher number of utilization to health center(p<0.01). Considering the work contents such as power blasting, spray, mixing and touch-up, the group of touch-up showed higher number of utilization to health center and this difference was statistically significant(p<0.001). Those who were not using the safety apparatus, showed higher number of utilization to health center, which was statistically significant(p<0.05). The degree of the knowledge on handling the solvent had no relation with using health center. 2) The results conducted from this study by multiple regression analysis in clarifying the factors affecting the number of utilization to health center, CE, exposure year and using safety apparatus was significant factor in utilization of health center.

• 환경위생공학
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• 제11권3호
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• pp.47-52
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• 1996

Personal exposure levels of $NO_{2}$ for office workers and housewives Living in A-San and neighboring prefectures were measured in two seasons with $NO_{2}$ filter badge. $NO_{2}$ concentrations in indoor and outdoor air in their offices and houses were also measured in the same periods. Personal exposure levels in winter ranged from 13 to 132 ppb and its distribution pattern was remarkably different from the other seasons (15.2-17.9 ppb). This fact suggests that use of heating apparatus affects largely $NO_{2}$ indoor air pollution in winter seasons. Actually, $NO_{2}$ exposure levels of subjects used Kerosene heater (43.6ppb) and gas heater (33.4ppb) were higher than those of subjects unused heating apparatus (18.0ppb). Personal exposure levels of $NO_{2}$ for man and woman Living in the same houses were correlated well each other. The time spent indoors for office workers and housewives were both longer than 22 hour a day. Home staying time was about 60% of total indoor staying time for office workers and 90% or more for housewives. Personal exposure levels were significantly related to indoor exposure levels at home all seasons. Furthermore, personal exposure levels could be estimated from $NO_{2}$ concentrations and staying times in various Living environment.

• BMB Reports
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• 제36권3호
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• pp.265-268
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• 2003

Retinoic acid (RA) can transform the Golgi apparatus (GA) into a diffuse vacuolar aggregate and increase the toxicity of some immunotoxins that enter into cells by receptor-mediated endocytosis. An ultramorphological study of the RA-induced GA disruption was performed on F2000 fibroblasts. Cultures were treated with 0.11 to $30\;{\mu}M$ RA for 7 - 180 min. The endocytosis of Limax flavus agglutinin-peroxidase conjugate (LFA), and the interactions between a phorbol ester (PMA) and RA concerning GA disruption, were examined. Exposure to $0.33\;{\mu}M$ RA for 20 min transformed the GA into vacuolar aggregate. These vacuoles were not involved in endocytosis since they remained unstained after endocytosis of LFA. However, the lysosomes were involved in endocytosis, as they were strongly stained. Therefore, a RA-induced shift towards lysosomal routing of the entered LFA was presumed. Exposure to PMA made cells resistant to the Golgi-disturbing effects of RA, indicating that protein kinase C plays an important role in this process.

• ALGAE
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• 제25권1호
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• pp.37-44
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• 2010

A tide-simulating apparatus was developed for culturing marine macroalgae. The objective of this study was to introduce a novel tide-simulating apparatus that can simulate a diurnal or semi-diurnal tidal cycle in the laboratory. In this apparatus, the seaweeds are move up and down and the water level remains the same during the simulated tidal cycle. The apparatus consists of 18 cylindrical culture tanks (3 blocks $\times$ 6 culture tanks) with 12 cm diameter and 24.5 cm long containing up to 2.5 L of seawater. There is a horizontal plate which covered all 18 culture tanks, and it is raised and lowered by a programmable motor that can regulate exposure time. In one application, seaweeds are attached to braided twine hung on Plexiglas air-tubing. The air-tubing is attached to a lid that is set on a horizontal plate. This apparatus is made of colorless Plexiglas to maximize light transmittance. This apparatus is easily disassembled and transportable to any indoor laboratory, wet laboratory, greenhouse, etc. This apparatus also offers considerable flexibility in terms of design. The size of culture tank can be redesigned by either increasing the height of cylinder or/and using a different diameter of cylindrical Plexiglas, therefore, larger/taller thalli can be cultivated. Growth rates of three eulittoral Porphyra species from different tidal elevations have been compared using this device.

• 한국방사선학회논문지
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• 제14권4호
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• pp.353-360
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• 2020

본 연구는 CBCT 장비의 표준 노출 조건(80 kV, 7 mA)을 기준으로 관전압과 관전류를 낮추어 촬영하면서 표준 노출 조건의 물리적 화질 요소값을 유지할 수 있는 노출 조건의 제시를 목표로 두고자한다. 영상의 물리적 화질 요소값의 측정을 위해 변조전달함수(MTF)가 분석되었고 선량 측정을 위해 선량-면적 곱(DAP)을 이용하였다. 관전압(80, 78, 76 kV)과 관전류(7, 6, 5, 4, 3 mA)의 15가지 조합의 노출 조건에서 Sedent ex IQ 팬텀 (Leeds Test Objects Ltd., Boroughbridge, UK)의 CBCT 영상을 얻었고 MTF 10이 각 조건에서 계산 되었다. 표준 노출 조건과 비교시 80 kV-6 mA, 80 kV-5 mA 노출 조건은 MTF 10에 있어 유의한 차이를 보이지 않았기에 본 연구에서 사용된 CBCT 장비의 경우, 80 kV-5 mA로 낮춘 노출 조건에서 물리적 화질요소값을 유지하면서 선량을 감소시킬 수 있는 것으로 판단되어진다.

• Safety and Health at Work
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• 제11권4호
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• pp.509-516
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• 2020

Background: Meta-analyses have shown firefighters to be at an increased risk of several cancer types. Occupational carcinogen exposure may explain these increased risks. This study aims to describe Norwegian fire departments' work conditions from 1950 until today, focusing on factors relevant for potential occupational carcinogen exposure. Methods: With the help of a reference group, we developed a questionnaire on topics related to occupational exposure to carcinogens for the period 1950-2018. Selected Norwegian fire departments provided department-specific responses. Results: Sixteen departments, providing fire services for 48% of the Norwegian population as of 2019 and mainly consisting of professional firefighters, responded to our questionnaire. The introduction of synthetic firefighting foams, more regular live fire training, the introduction of chemical diving, and a higher number of diesel-driven fire service vehicles were identified as changes thought to increase exposure to occupational carcinogens. Changes thought to decrease exposure included the switch from negative to positive pressure self-contained breathing apparatuses, the use of self-contained breathing apparatuses during all phases of firefighting, the use of ventilating fans during firefighting, increased attention to flammable materials used during live fire training, increased attention to handling and cleaning of turnout gear and other equipment, and installment of exhaust removal systems in apparatus bays. Conclusion: Norwegian fire departments' work conditions have seen several changes since 1950, and this could influence firefighters' occupational carcinogen exposure. A peak of carcinogen exposure may have occurred in the 1970s and 1980s before recent changes have reduced exposure.

• Environmental Analysis Health and Toxicology
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• 제12권3_4호
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• pp.43-54
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• 1997

Species, doses and routes extrapolation can be sucessfully carried out by using a physiologically-based pharmacokinetic (PBPK) approach. And PBPK approach to assess risk of hazardous chemicals is reasonable whatever the exposure scenarios are happened. Both partitioning coefficients of chemical between tissue and blood and enzymatic metabolic rate constants are key parameters to build up the PBPK model. In this study, we tried to estimate in vitro metabolic rate constants using a special apparatus instead to measure the in vivo constants which are used to PBPK simulation since the in vitro tests are less expensive and more convenient than in vivo tests. For the purpose, we designed and tested the new system to measure continuously the headspace concentration of VOC. The newly designed system is composed with a diffusion chamber which generates gaseous substrate, a reaction vessel with a recirculating pump to establish a closed system, an autbmatic sampler from a gas phase, a gas chromatography to analyze the headspace. In addition, a cold water condenser is attached between the reaction vessel and pump to reduce the content of gaseous moisture which interferes with chemical analysis. To validate the newly developed methodology, in vitro metabolic rate constants of trichloroethylene (TCE) as a prototype VOC were estimated by simulating observed results with an ACSL program. The simulated results are consistent to those estimated by the other research groups. This finding suggests that our newly designed closed system may be a useful apparatus to estimate in vitro metabolic rate constants for VOC.

• 한국전자파학회논문지
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• 제14권10호
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• pp.1017-1023
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• 2003

최근 전기전자기기 등의 사용에 의한 전자파 발생으로 인체 위해성에 대한 논쟁이 시작되었으며, 지난 20여년 동안 고압선로에서 발생되는 극저주파 전자기장에 만성적인 노출로 인한 인체 위해성에 관한 역학적 연구가 많은 나라에서 진행되어 왔다. 2 mG 이상의 자기장에 지속적으로 노출될 경우에 소아백혈병 등과 같은 암 질병이 발생한다는 연구논문이 발표되고 있다. 고압선로로부터 발생되는 전자파에 의한 장기적인 노출과 암 발생에 관한 상관관계가 과학적으로 명확하게 규명되지 않았고, 또한 잠재적인 건강 위험성에 대한 평가가 입증되지 않았음에도 불구하고, 2000년에 스위스는 민감한 정온시설 지역에 대하여 엄격한 예방적 원칙을 적용하고 있으며, 여러 국가들도 이러한 건강 위험성에 대한 저감정책의 일환으로 자기장 노출 가이드라인을 설정하려는 움직임을 보이고 있다. 다시 말하면, 과학적인 불확실성이 높은 상황에서도 과학적인 연구결과만을 기다리지 않고, 잠재적인 위험성을 예견하여 차후 심각한 위험성에 대한 조치를 미리 적용하는 관리정책이다. 우리나라에서는 아직 이러한 건강 위험성에 대한 관리정책이 아직 마련되어 있지 않은 상태이다. 따라서 고압선로에서 발생되는 전자기장에 만성적인 노출과 소아백혈병 발생과의 상관관계를 밝히기 위한 연구를 지속적으로 해야 하며, 유아원, 초등학교 등의 환경민감시설에 대한 단계별 전자파 방출 권고치를 설정하는 등의 예방적 관리정책을 부분적이나마 도입할 필요가 있다.