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Evaluation of the critical stroke of an earthworm-like robot for capsule endoscopes
Kwon, Jiwoon,Park, Sukho,Park, Jongoh,Kim, Byungkyu SAGE Publications 2007 Proceedings of the Institution of Mechanical Engin Vol.221 No.4
<P>Recently, the capsule endoscope has been highlighted for the patient's convenience and the possibility of application in the small intestine. However, the capsule endoscope has some limitations in obtaining an image of the digestive organ because its movement depends only on the peristaltic motion. In order to solve these problems, it is necessary to determine the locomotive mechanism of the capsule endoscope. Therefore, the present authors have already proposed an earthworm-like robot, which has a locomotive mechanism. However, this mechanism should be designed so that the earthworm-like robot has a larger stroke than the critical stroke required to perform motion inside the small intestine. In this study, therefore, not only is the modelling of the locomotive process based on a biomechanical study presented but also the movement of the earthworm-like robot in the small intestine is simulated. Through the simulation process, the variation in the critical stroke with regard to the elastic modulus of the mesentery is investigated. Finally, from an in vitro test of the proposed robot, it is found that the experimental result is very similar to that of the simulation. Consequently, the present work will provide guidelines for designing an earthworm-like robot for diagnosis of the small intestine.</P>
Development of the KOSHA Proficiency Testing Scheme on Asbestos Analysis in Korea
Kwon, Jiwoon,Jang, Konghwa,Hwang, Eunsong,Kim, Ki-Woong Occupational Safety and Health Research Institute 2017 Safety and health at work Vol.8 No.3
This commentary presents the regulatory backgrounds and development of the national proficiency testing (PT) scheme on asbestos analysis in the Republic of Korea. Since 2009, under the amended Occupational Safety and Health Act, the survey of asbestos in buildings and clearance test of asbestos removal works have been mandated to be carried out by the laboratories designated by the Ministry of Employment and Labor (MOEL) in the Republic of Korea. To assess the performance of asbestos laboratories, a PT scheme on asbestos analysis was launched by the Korea Occupational Safety and Health Agency (KOSHA) on behalf of the MOEL in 2007. Participating laboratories are evaluated once a year for fiber counting and bulk asbestos analysis by phase contrast microscopy and polarized light microscopy, respectively. Currently, the number of laboratory enrollments is > 200, and the percentage of passed laboratories is > 90. The current status and several significant changes in operation, sample preparations, and statistics of assigning the reference values of the KOSHA PT scheme on asbestos analysis are presented. Critical retrospect based on the experiences of operating the KOSHA PT scheme suggests considerations for developing a new national PT scheme for asbestos analysis.
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.
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.