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- 저자 : 권지운 ( Jiwoon Kwon ) (검색결과 13 건)
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충청북도 제천시 폐석면광산 주변 토양에서 검출되는 각섬석의 크기 분포
권지운,최성원,김현욱,Kwon, Jiwoon,Choi, Sung Won,Kim, Hyunwook 대한자원환경지질학회 2014 자원환경지질 Vol.47 No.5
본 연구는 석면형태와 비석면형태의 구분을 위하여 충청북도 제천시에 소재한 한 폐석면광산 지역의 토양 중 트레모라이트와 악티노라이트 섬유의 크기 특성을 파악하였다. 폐석면광산 주변지역의 토양과 트레모라이트 석면 암석을 채취하고, 투과전자현미경으로 길이 $5{\mu}m$ 이상이며 길이대너비 비율이 3:1 이상인 섬유의 크기를 측정하여 알려진 석면형태와 비석면형태를 보이는 트레모라이트의 크기 분포와 비교하였다. 연구 결과 섬유의 너비는 기하평균으로 토양시료 $1.2{\mu}m$, 석면 암석 $0.3-0.6{\mu}m$, NIST 트레모라이트 $1.3{\mu}m$, HSL 트레모라이트 $0.2{\mu}m$ 이었다. 길이대너비 비율은 기하평균으로 토양시료 7.3, 석면 암석 13.7-30.1, NIST 트레모라이트 7.2, HSL 트레모라이트 37.8 이었다. 토양시료는 알려진 석면형태의 트레모라이트 뿐만 아니라 비석면형태의 트레모라이트에 비해서도 가늘고 길이대너비 비율이 큰 섬유를 적게 함유하였다. 따라서 연구 대상 토양시료 중의 트레모라이트-악티노라이트는 전형적 석면형태로 분류할 수 없으며, 대부분은 광산 및 채석장으로부터 바람에 의해 비산된 석면으로 인한 오염의 결과가 아닌 것으로 추정된다. 토양 중 석면의 관리를 위해서 석면 오염 여부를 조사 시에는 감섬석의 크기 분포가 함께 고려되어야 한다. This study is for discrimination between asbestiform and non-asbestiform based on size characteristics of tremolite-actinolite fibers in soils from a closed asbestos mine, Jecheon, Chungcheongbuk-do, Korea. Soils and tremolite asbestos rocks were collected from a closed asbestos mine area. The dimensions of fibers with minimum $5{\mu}m$ in length and 3:1 in aspect ratio were measured using transmission electron microscopy (TEM) and compared to the known tremolite populations ranging from asbestiform to non-asbestiform. The geometric means of width of soils, asbestos rocks and National Institute for Standard and Technology (NIST) and Health and Safety Laboratory (HSL) reference samples were $1.2{\mu}m$, $0.3-0.6{\mu}m$, $1.3{\mu}m$ and $0.2{\mu}m$, respectively. The geometric means of aspect ratio of soils, asbestos rocks and NIST and HSL reference samples were 7.3, 13.7-30.1, 7.2 and 37.8, respectively. The population of tremolite-actinolite fibers from soils compared to known asbestiform and non-asbestiform tremolite was lack of thin and high aspect ratio fibers. Upper results suggest that tremolite-actinolite fibers in soils cannot be classified into a commercial grade asbestos. The tremolite-actinolite fibers do not mainly appear to be the result of contamination from distance asbestos sources by wind. For the management and control of asbestos in soils, size distributions of amphiboles should be incorporated into asbestos survey results of soils.
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권지운(Jiwoon Kwon),박석호(Sukho Park),김병규(Byungkyu Kim),박장현(Jahng-hyon Park) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.5
In order to develop the earthworm-like locomotive mechanism, which will be mounted in capsule type endoscope, bio-material property is essential information. Especially, the friction force between capsule endoscope and the tissues of the gastro-intestinal (GI) tract is crucial parameter since it affects the mobility of endoscope. In this paper, we propose the bio-material property measuring system which can supply the information to design of the locomotive mechanism. This system is actuated by DC motor and controlled by PID controller. Also, the measured data is acquired by AD board (D-space Inc.). By using the proposed measuring system, we evaluate the effects of design parameters that affect the friction force between the capsule endoscope and GI tract to get the dominant ones. Through the test, we conclude that diameter and shape are major parameters, however, velocity, mass and stroke are minor parameters of friction force.
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탄소나노튜브 복합체 취급 작업자의 공기 중 입자상 물질 노출 특성
권지운 ( Jiwoon Kwon ),김성호 ( Sungho Kim ),장미연 ( Miyeon Jang ) 한국산업보건학회 (구 한국산업위생학회) 2020 한국산업보건학회지 Vol.30 No.1
Objectives: The purpose of this case study is to assess workers’ exposure to carbon nanotubes (CNTs) and characterize particles aerosolized during the process of producing CNT-enabled polytetrafuoroethylene(PTFE) composites at a worksite in Korea. Methods: Personal breathing zone and area samples were collected for determining respirable concentrations of elemental carbon (EC) using NIOSH(National Institute for Occupational Safety and Health) Method 5040. Personal exposure to nano-sized particles was measured as the number concentration and mean diameter using personal ultrafine particle monitors. The number concentration by particle size was measured using optical particle sizers (OPS) and scanning mobility particle sizers (SMPS). Transmission electron microscopy (TEM) area samples were collected on TEM grids and analyzed to characterize the size, morphology, and chemistry of the particles. Results: Respirable EC concentrations ranged from 0.04 to 0.24 μg/m<sup>3</sup>, which were below 23% of the exposure limit recommended by NIOSH and lower than background concentrations. Number concentrations by particle size measured using OPS and SMPS were not noticeably elevated during CNT-PTFE composite work. Instant increase of number concentrations of nano-sized particles was observed during manual sanding of CNT-PTFE composites. Both number concentrations and mean diameters did not show a statistically significant difference between workers handing CNT-added and not-added materials. TEM analyses revealed the emission of free-standing CNTs and CNT-PTFE aggregate particles from the powder supply task and composite particles embedded with CNTs from the computer numerical control (CNC) machining task with more than tens of micrometers in diameter. No free-standing CNT particles were observed from the CNC machining task. Conclusions: Significant worker exposure to respirable CNTs was not found, but the aerosolization of CNTs and CNT-embedded composite particles were observed during handing of CNT-PTFE powders and CNC machining of CNT-PTFE composites. Considering the limited knowledge on the toxicity of CNTs and CNT composite particles to date, it seems prudent to take a precautionary approach for the protection of workers’ health.
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작업환경측정시료의 분석수탁기관과 자율정도관리 참여와의 연관성
김성호 ( Sungho Kim ),권지운 ( Jiwoon Kwon ),조현민 ( Hyunmin Cho ),박해동 ( Hae Dong Park ) 한국산업보건학회 (구 한국산업위생학회) 2021 한국산업보건학회지 Vol.31 No.2
Objectives: The necessity of samples for analysis requested by working environment monitoring institutes (WMIs) has grown recently. The collection of samples of a few chemical substances requested by WMIs is allowed under the current occupational safety and health act in Korea, leading to an expansion of samples for analysis requested by institutes (SRIs). The objective of this study was to identify the number of institutes for analyzing requested samples (IARS), SRIs, and their participation in a non-mandatory proficiency test. Methods: Questionnaires were completed by all WMIs. The collected information was quantity of analysis equipment, sorting of chemicals from SRIs, and the number of SRIs. This was compared in terms of the participation in the non-mandatory proficiency test. Results: All WMIs in Korea responded to the survey, establishing a 100% response rate. There were 52 (29%) IARS among the 179 WMIs in Korea. The total number of samples of acid for ion chromatograph (IC) analysis requested by WMIs was 21,165, which is the most. Even the number of IARS for crystalline silicon oxide was less than other top-five IARS. The total amount of samples was 13,863, which was the second most. The calculated participation score for IARS was significantly higher than other WMIs (p<0.001). According to participation in the non-mandatory proficiency test by type of substance, such as crystalline silicon oxide and formaldehyde among IARS, the number of SRIs from those IARS was significantly higher than IARS that did not participate in the proficiency test (p<0.05). Conclusions: IARS had a high frequency of participation in the non-mandatory proficiency test and the number of SRIs at IARS participating in the proficiency test was higher among IARS. With the revision of the occupational health and safety act in Korea, the number of IARS participating in the non-mandatory proficiency test might increase.
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유형민(Hyung Min Yu),조용근(Yong Geun Cho),권지운(Jiwoon Kwon),한승오(Seung Oh Han) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.4
로봇암의 회전 토크를 높이기 위해 사용되는 감속기는 모터, 모션 제어기와 함께 산업용 협동 로봇의 3 대 핵심 부품으로써 로봇의 성능을 결정하는 하나의 중요한 요소이다. 따라서 감속기의 신뢰성은 로봇의 수명을 결정하는 핵심 요소이며 전세계적으로 유명한 선진사 제품의 감속기는 30,000 시간 이상의 내구성을 보증한다. 본 연구에서는 선진사의 감속기 내구 수명을 분석하여 향후 국산 제품의 내구 수명을 결정하는 각 파라미터의 기준을 제시하기 위해 가속계수를 적용한 벤치 테스트를 통해 감속기 표면에서 발생하는 온도와 시험 종료 후 초기 감속비 유지 여부를 분석하였다. 가속계수는 Weibull분포에 기반한 평균 무고장 시간을 산출하고, 하모닉 드라이브의 허용 토크를 고려하여 산출되었으며 시험 결과 감속비의 오차는 5% 미만, 표면 온도는 안정구간에서 60℃를 유지하였다. Harmonic reducer used to enhance the torque of robot arm is one of the core part applied to collaborative industrial robot, and therefore the reliability of this part is crucial to determine the robot performance. In this study, reduction ratio and surface temperature was suggested as parameters to define the functional failure in reliability perspective. The harmonic reducer produced by leading company was studied experimentally by accelerated life testing technique for analyzing the suggested parameters. Acceleration factor was obtained by mean time between failure (MTBF) based on Weibull distribution with consideration of allowable torque for harmonic drive. It was noted that the discrepancy of the reduction ratio is less than 5% and the temperature is maintained at 60℃ in the steady state. Consequently, this result can be used in new reducer development as reliability criteria.
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