• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1995.03a
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• pp.40-62
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• 1995

A micro positioning system using piezoelectric actuators have very wide application region such as ultra-precision machine tool optical device measurement system. In order to keep a high precision displacement resolution it to useful to take a position sensor and feedback of the error. From the practical point of view high-resolution displacement sensor systems are very expensive and it is difficult to make such a sensitive sensor work properly in a poor operational environment of industry. In this study a piezo-electric micro-depth control system which does not require position sensor but piezoelectric voltage feedback has been developed. It is driven by hysteresis-considering reference input voltage calculated in advance and actuator/sensor characteristics of piezoelectric materials. From the result of experiments a fast and stable response of micro-depth control system has been achieved and an efficient technique to control the piezoelectric actuator suggested.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.1014-1019
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• 2003

It seems inevitable for residential buildings to be high-rise and allocated near traffic roads due to the overcrowding in urban area. Acoustic environment in those area has been seriously deteriorated by the increase of traffic vehicles. Commonly used sound barriers have a limitation in controlling noise due to diffraction noise of sound barrier. Hence sound barrier is not effective to attenuate noise especially for the residential units in high level. This work aims at evaluating noise reduction according to the tunnel section shape by using 1/5 scale model. We carried out a number of field measurements for 1/5 scale model of Noise Barrier Tunnel with various sectional shape. The results from predictions and the measurement show generally good agreement.

• Journal of the Korea Safety Management & Science
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• v.12 no.2
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• pp.41-48
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• 2010

The Purpose of this study was to comprehend the influence that worker's job stress caused by the distinct characteristics of construction work affect on construction management. Proven through previous studies of job stress measurement method, physical environment, job demands, job autonomy, interpersonal conflict are derived as typical factors. We analyzed causal relationships between the factors using structural equation modeling under the hypothesis that job stress have effect on the construction management. As a result, successful job stress management for construction management plan is proposed.

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2004.05a
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• pp.195-201
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• 2004

In design stage of high precision manufacture/inspect ion FAB building, it is necessary to investigate the vibration allowable limits of high precision equipment and to study a structure dynamic characteristics of C/R and Sub-structure in order to provide a structure vibration environment to satisfy thess allowable limits. The aim of this study is to investigate the dynamic characteristics of PC-Type mock-up structures designed for next TFT LCD FAB through vibration measurement and analysis procedure, therefore, to provide a proper dynamic structure design for high precision manufacture/inspection work process, which satisfy thess allowable limits.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11b
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• pp.1361-1364
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• 2001

The recent national contract (Ecotechnopia 21) supported by the ministry of environment puts much significance on new issues for the assessment of human effects arising from vibration and noise exposed to human. This paper focuses only on hand-arm vibration since it has been a major problem in protecting vibration exposure to human. To set up a systematic way of assessing adverse effects of hand-arm vibration, surveys were made on recent international standards and researches related to hand-arm vibration. The measurement and evaluation methods of hand-arm transmitted vibration, the relationship between vibration exposure and effects on health, and the assessment methods of nerve dysfunctions are addressed in this paper. Those methods are linked into a logical way of assessing effects of hand-arm vibration on human. Finally, the current activities and achievements in this work are briefly summarised.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11b
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• pp.691-694
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• 2001

The recent national contract (Ecotechnopia 21) supported by the ministry of environment puts much significance on new issues for the assessment of human effects arising from vibration and noise exposed to human. This paper focuses only on hand-arm vibration since it has been a major problem in protecting vibration exposure to human. To set up a systematic way of assessing adverse effects of hand-arm vibration, surveys were made on recent international standards and researches related to hand-arm vibration. The measurement and evaluation methods of hand-arm transmitted vibration, the relationship between vibration exposure and effects on health, and the assessment methods of nerve dysfunctions are addressed in this paper. Those methods are linked into a logical way of assessing effects of hand-arm vibration on human. Finally, the current activities and achievements in this work are briefly summarised.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.11a
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• pp.500-505
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• 2000

Recently, with the increasing of construction works, large construction equipment are used to reduce the term of work and labor cost in construction field. Therefore, construction equipment noise has caused much annoyance for a number of dweller in nearby construction field and it has become a very serious problem in our living environment. Neverthless, in our country, adequite guidelines for the construction equipment noise are very deficiency because of the lack of basic data and insufficient research works. From this point of view, this study attempts to survey the characteristics of attenuation and propagation of Sand Drain Method in construction field. On the basis of measurement value, we analysed about prediction possibility of Sand Drain Method. This study also present a basic data found a effective plans for Sand Drain Method.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.56 no.1
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• pp.45-54
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• 2020

In this study, an automatic system for improving the working environment and increasing production efficiency of a laver aquaculture industry in Korea was developed by combining a hydraulic control system and a load cell in a current landing work of the laver. The improved gathering laver system allowed the automatic gathering process of the laver in the sea with the hydraulic control system connected to a cutting machine of the laver on the operating ship, which has been used for gathering the laver semi-automatically in a form of the traditional farming method. The transporting process of the laver from an operating ship to the land was improved as follows. A frame installed on the operating ship and the bag nets were designed and made to hold about 1,000 kg of the laver inside. The bag nets contain the laver on the improved operating ship were tied in knots and hooked on a crane using a load cell. The weight is measured immediately by lifting the bag nets through the load cell system. Weight information is communicated to the fishermen and successful bidders through the application. The advantages of the improved system can help fishermen to fish by improving their working environment and increasing production efficiency. The field survey to improve the landing operation of the laver aquaculture was conducted in Gangjin, Goheung, Shinan, Wando, Jindo, and Haenam in South Jeonnam Province. A total of 10 sites including Gunsan in Jeonbuk Province, Daebu Island in Ansan City, Jebu Island in Hwaseong City in Gyeonggi Province, and Seocheon in Chungnam Province were searched to collect data. Prototypes of the system were tested at the auction house of laver located in Goheung, where laver collection using hydraulic control and landing using road cell could be improved.

• Journal of the Korean Institute of Gas
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• v.18 no.2
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• pp.55-61
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• 2014

In this study, we evaluated the measurement of working environment, the amount of exposure, the hazards and risks of biphenyl, that was registered as 2A in IARC. Based on the exposure scenario, it was calculated that the exposure amounts are $1.0{\times}10^{-2}$, $4.2{\times}10^{-4}$, $7.0{\times}10^{-6}mg/m^3$, respectively, and the $RfC_{work}$ is 0.21, 2.13, 0.53 $0.31mg/m^3$ as carcinogenicity, target toxicity (oral), target toxicity (inhalation), developmental toxicity, respectively. According to these hazards evaluation and risk assessments, it was estimated that 0.57, 0.39 as carcinogenicity and non-carcinogenicity (developmental toxicity), respectively. It was also estimated relatively lower risks below 1. But since biphenyl is hazardous used much amounts, and could be exposed to workers directly, it was determined to require exposure monitoring to protect workers' health.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.33 no.3
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• pp.273-279
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• 2023

Objectives: Objectives of this study were: 1) to introduce industrial situation and health hazards of synthetic fiber, 2) to review a case of chronic obstructive pulmonary disease in a worker exposed to synthetic fiber reported to the Korea Occupational Disease Surveillance Center, and 3) to suggest supplementary measures for the occupational health system for workers exposed to synthetic fibers. Methods: Respiratory exposure, health hazards, and exposure standards for synthetic fiber dust in Korea and other countries were reviewed. In addition, a case of chronic obstructive pulmonary disease due to exposure to nylon dust reported to the Korea Occupational Disease Surveillance Center was reviewed and summarized. Results: The worker was a 53-year-old non-smoking male who had been involved in the nylon weaving process for 26 years. He had shortness of breath from three years ago. He was diagnosed with chronic obstructive pulmonary disease. PM1.0, PM_2.5, and PM10 were measured at 26.6 ㎍/m³, 48.2 ㎍/m³, and 91.7 ㎍/m³, respectively. Fiber components estimated as nylon fiber were detected in the microscopic examination of a solid sample. Conclusions: For workers exposed to synthetic fiber dust, special health examinations of the respiratory system, regular work environment measurement, and work environment management through workplace health management should be performed. It is necessary to research on health effects of synthetic fibers.