• Journal of Environmental Science International
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• v.17 no.1
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• pp.45-56
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• 2008

This study was to assess the lifetime cancer and non-cancer risk of exposure of worker and user at public facilities in Korea to volatile organic compounds (VOCs). We measured the concentrations of two aldehydes and five VOCs in indoor air at 424 public buildings that 8 kinds of public facilities (70 movie theaters, 86 offices, 86 restaurants, 70 academies, 22 auditoriums, 30 PC-rooms, 30 singing-rooms and 30 bars) all over the country. There were estimated the human exposure dose and risks with averages of the using-time and frequency for facility users and office workers, respectively. Carcinogens (formaldehyde, acetaldehyde, and benzene) were estimated the lifetime excess cancer risks (ECRs). non-carcinogens (toluene, ethylbenzene, xylene, and styrene) were estimated the hazard quotients (HQs). The average ECRs of formaldehyde and benzene for facility worker and user were $1{\times}10^{-3}{\sim}1{\times}10^{-4}\;and\;1{\times}10^{-4}{\sim}1{\times}10^{-5}$ level, respectively, in all facilities. HQs of four non-carcinogens did not exceed 1.0 for all subjects in all facilities. The estimated ECRs for restaurant and auditorium were the highest, and the PC-room and bar were the next higher facilities. Furthermore, people in a smoking facility had the highest cancer risk. Higher ECRs of formaldehyde and benzene were observed in indoor smoking facilities such as restaurant and auditorium. Higher HQs of toluene and xylene were observed at the restaurant and office building.

• Journal of Environmental Science International
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• v.3 no.1
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• pp.65-76
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• 1994

The regiospecific potential for the reductive dechlorination of 2-, 3-, 4-, 2, 3-, 2, 4-, and 3, 4-chlorophenols (CPs) was studied in mono- and di-CP(DCP) adapted sediment slurries(10% solids). Freshwater sediments adapted to transform 2-CP dechlorinated all tested mono- and di-CPs except 4-CP without a lag period. Adaptation to 2-CP, thus, enhanced the onset of dechlorination of 3-CP and all ortho-substituted CPs tested. Sediment adapted to transform 3-CP dechlorinated all test CPs, except 4-CP and 2, 4-DCP, without a lag period. Sediment adapted to individual DCPs (2, 3-, 2, 4-, and 3, 4-DCP_ exhibited dechlorination(no lag phase) of 2-CP, 2, 3-, 2, 4-, and 3, 4-CDP. Interestingly, meta-cleavage of 3, 4-DCP in all tested adapted sediment occurred, while para-cleavage occurred in 3, 4-DCP adapted sediment. Sediment adapted to dechlorinate ortho and meta-chlorines exhibited a preference for meta following ortho-cleavage, but not for para-cleavage, while the preference for reductive dechlorination was ortho>meta>para for mono-CPs and ortho>para>meta for DCPs in unadapted freshwater anoxic sediments.

• Journal of the Korean Society of Tobacco Science
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• v.36 no.1
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• pp.20-25
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• 2014

As part of a balanced testing battery, subchronic inhalation studies on rats are performed to ensure that proposed cigarette modifications do not increase the toxicity of smoke and to demonstrate any instances where a modification may actually contribute to harm reduction. For subchronic inhalation studies with aerosols, the OECD suggests an exposure regimen of 6 hours/day (OECD Guideline 413, 1981), but alternative regimens have also been published: 1 hour/day and $2{\times}1$ hour/day. The aim of this study was to validate a rodent nose-only exposure system for the assessment of inhalation toxicity of cigarette smoke. In this study, cigarette smoke exposure system is consisted of cigarette smoke generator, smoke concentration adjusting system, and 20-port nose-only exposure system. Male SD rats were exposed for 35 days ($2{\times}1$ hour/day) to 3R4F Reference cigarette smoke and analysed major monitoring items of OECD Gudeline 413. WTPM, was measured in the test atmosphere, respiratory function (Buxco Biosystems) during exposure, postexposure urinary exposure biomarkers and alveolar neutrophiles in BAL fluid (Day 35) were evaluated. Validation demonstrated steady WTPM ($257{\pm}20ug/L$, $502{\pm}27ug/L$) and spatial uniformity (<10%). Nose port temperature ($22{\sim}26^{\circ}C$ and RH (45~75%) were acceptable over 35 days. Reductions in respiratory rate and minute volume and increase in the neutrophiles in BALF and the urinary exposure biomarkers were observed cigarette smoke dose dependently. This validation and 35-day inhalation study has shown that the rodent nose-only exposure system may be useful in the inhalation toxicity assessment of cigarette smoke.

• Journal of the korean academy of Pediatric Dentistry
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• v.33 no.4
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• pp.704-709
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• 2006

Ectopic eruption should be understood as a change in the course of the normal eruption path of a dental bud at any moment in its origin. Transposition is a unique and extreme form of ectopic eruption. The treatment for ectopic eruption and transposition is various from simple observation to surgical exposure and orthodontic traction, according to direction of erupting tooth degree of developing root apex and eruption space etc. Autotransplantation is transplantation of tooth from one area of the mouth to another in the same individual or is moving a eruption tooth into extraction socket or surgically prepared socket, and autotransplantation is considered as a treatment of choice for the ectopic eruption when orthodontic traction is unable or when tooth movement is limited. These cases which were treated with autotransplantation of maxillary lateral incisor and maxillary canine were reported, and good esthetic and functional result were induced.

• Applied Chemistry for Engineering
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• v.29 no.5
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• pp.489-496
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• 2018

Fuel cells are seen as eco-friendly energy resources that convert chemical energy into electrical energy. However, proton exchange membrane fuel cells (PEMFCs) have problems such as the use of expensive platinum catalysts for the reduction of conductivity under high temperature humidification conditions. Thus, an anion exchange membrane fuel cell (AEMFC) is attracting a great attention. Anion exchange fuel cells use non - Pt catalysts and have the advantage of better efficiency because of the lower activation energy of the oxygen reduction reaction. However, there are various problems to be solved including problems such as the electrode damage and reduction of ion conductivity by being exposed to the carbon dioxide. Therefore, this mini review proposes various solutions for different problems of anion exchange fuel cells through a wide range of research papers.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.171-171
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• 2011

헬륨냉동계통은 연구용 원자로인 하나로에서 냉중성자를 생산할 수 있도록 설치된 수조내기기 내의 감속재인 수소가 정상적으로 열 사이펀을 유지하기 위한 주요 계통이다. 헬륨냉동계통은 헬륨가스를 압축하는 헬륨 압축부분과 헬륨가스를 팽창시켜 저온을 생성시키는 헬륨 팽창부분으로 나누어진다. 헬륨 압축부분은 두 개의 스크류가 맞물려 회전하면서 약 1.05 bar(a)의 헬륨가스를 최대 13 bar(a)까지 압축시키는 압축기가 있으며, 헬륨 팽창부분인 냉동박스의 팽창 터빈은 self-acting gas bearing에 의해 구동되며, 저온모드 운전 시작시 헬륨 압축부분에서 일부의 가스는 팽창 터빈 축(shaft)으로 유입되어 회전속도가 서서히 증가하면서 고속으로 회전하여 극저온의 헬륨가스(14~18 K)를 생성하는 주요 기기이다. 헬륨을 팽창하는 부분인 냉동박스 내로 헬륨 압축가스를 유입하기 전에 압축된 헬륨가스 내 불순물의 순도를 분석하여 냉동박스의 주요 부품인 팽창터빈의 운전에 영향을 미치지 않는 것이 가장 중요하다. 따라서 헬륨 저압측에 헬륨가스 내 불순물 즉, 수소($H_2$), 수분($H_2O$), 질소($N_2$), 탄화수소류(CxHy) 및 오일(Oilaerosol) 등의 함량을 분석하기위해 가스 분석기가 설치되어 있으며, 냉동박스 내로 유입되기 전에 헬륨압축에서 순환되는 가스 내 불순물인 수분, 질소, 탄화수소류 및 오일은 10 vpm 이하이어야 하며, 수소 함량은 0.1 % 이내이어야 한다. 헬륨 압축부분에서 순환되는 가스의 불순물이 요구 조건에 만족하도록 헬륨 고압측과 헬륨 저압측에 cryogenic adsorber를 설치하여 가스 내 불순물을 제거하는 가스순도제어 작업을 수행해야 한다. cryogenic adsorber를 사용하기 위해서는 장치 내의 불순 가스를 공정진공도(1.33 X $10^{-3}$ mbar) 이하로 진공배기하는 작업이 매우 중요하다. 이는 계통의 헬륨가스가 오염되지 않도록 하는 것으로 cryogenic adsorber 내에는 액체질소를 충전하여 액체질소 온도에 노출된 활성탄층을 헬륨가스가 흐르면서 수분, 질소, 탄화수소류 및 오일 등이 제거된다. 이 논문에서는 헬륨냉동계통의 가스 순도 제어 작업을 통해 헬륨가스의 순도가 요구조건 이하로 만족하며, 팽창 터빈의 운전에 영향을 미치지 않음을 기술하고자 한다.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2003.11a
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• pp.202-206
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• 2003

In this study, a modified bituminization technology has been developed, which needs no grinding of the granular resin waste, and enables the solid form to keep its shape stability as good as that of a cemented solid from Also, the study intended to apply the developed technology to the practical treatment of radioactive resin waste. In the experiment, the granular type resin was used and the straight-run distillation bitumen with penetration rate 60/70 was used as the solidifying agent. The PE was used as the additive. The shape stability increased remarkably with the additive of PE, which act as a binder in the solid form. The shape of the solid form was maintained without failure during the long-term exposure test when the additive content of spent PE is more than 10wt%. The proper ranges of bitumen content, PE content and operating temperature are 30-50wt%, 10-20wt% and $180^{\circ}C$ respectively. The bituminized solid form of radioactive resin waste by the technology of this study has the remarkably superior quality than the conventional solid forms, partially for the shape stability.

• Journal of the Korean Wood Science and Technology
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• v.29 no.4
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• pp.60-66
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• 2001

For examine anti-degradation factors of acetylated wood, acetylated wood was incubated on Trametes versicolor. The laccase activity was examined in broth culture and solid fermentation that contain acetylated chips. The change of acetyl groups and chemical composition in the acetylated wood having massloss analysed by $^{13}C$-CP/MAS NMR. The laccase activity was detected in broth culture. When the T. versicolor contact to acetylated wood directly, the laccase activity was very low and couldn't maintain during test periods. Through the analysing of $^{13}C$-CP/MAS NMR, the acetylation took place carbohydrates as well as lignin and hydroxyl group of amorphous region was more easily substituted that of crystalline region The spectral analyses of $^{13}C$-CP/MAS NMR were shown that introduced acetyl bond was stable against fungal attack.

• The Journal of the Korea institute of electronic communication sciences
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• v.12 no.6
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• pp.1121-1126
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• 2017

Various studies such as INS(: Inertial Navigation System) are conducting to estimate the position of UAV, because the GPS information of UAV is at risk like the GPS jamming. The position estimation using DoA and RTT are used to apply many radar systems, and that process can be applied in datalink of UAV. The general monopulse feed in UAV datalink is Multi-horn, because of the wide BW(: Band Width) and frequency range. And it needs wide SNR range of tracking because of the limited transmit power of airborne unit. The estimation error of position increase at low SNR, and the DoA is valid in only 3dB beam width but high SNR causes false of mainlobe detection because of large sidelobe. In this paper, We propose the method to achieve higher accuracy of DoA estimation on low SNR and review some idea that able to detect mainlobe.

• Journal of Environmental Impact Assessment
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• v.28 no.6
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• pp.616-625
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• 2019

Health impact assessment is implemented within the Environmental impact assessment for the purpose of minimizing health damage by predicting the impact on human health following implementation of the development project. In health impact assessment, manual revision is required due to the lack of consistency in the method of estimating hazardous air pollutants emissions. This study estimated the emissions by calculating the emissions of hazardous air pollutants based on the actual industrial complex development cases and completed health impact assessments. As a result of risk assessment based on exposure concentration using CALPUFF model, the risk assessment results were different for each of the emission estimation methods, and manual improvement on the emission estimation method is needed.