• Journal of Fisheries and Marine Sciences Education
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• v.5 no.1
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• pp.23-30
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• 1993

The Korea Seaman's Act is providing that fishermen s salaries are exceptionally defined and working hours and paid leave are not defined at all. Significant problems of Fishermen's Labor Condition are, (1) It is hard to guarantee the basic right of fishermen as their wages are variable depending on the catch. (2) Excessive working hours would hamper the labor reproduction ability and increase the frequency of disaster. (3) Moreover, fishermen have to search for a new job following the lay off after working aboard during the period defined by contract. The possible implement of Seamen's Act are : (1) The wage system must be unified by regular wages. If it is hard to perish the lay system its relative importance should be diminished whereas the fixed minimum wages and the allowance depending on the position and working days should be paid. (2) This discrimination of the fishing vessels from merchant should be eliminated by removing the item on the Act which excludes the fishermen on the working hours. If it is hard to do so practically the lower regulations defining the maximum periods of duty and minimum periods of rest for fishermen must enact separately as in Japan and England. (3) The difference in the provisions of paid leave between the merchant seamen and fishermen must be abolished (4) It is the most desirable to improve the fishermen's labor conditions through the completion of the Act. However, before doing this, the employers and employees must try to solve the problems through the collective agreement by themselves.

• Journal of The Korean Society of Agricultural Engineers
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• v.62 no.1
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• pp.105-115
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• 2020

With the decrease of the agricultural population in Korea, the workers who is vulnerable to labor are increasing in agricultural industry because of aging, feminization of population. They are exposed in poor working environment with higher temperature and concentrations of dust, gas. Higher concentration of harmful gas and dust can cause chronic and acute disease to workers depending on exposure intensity and frequency. In order to improve the working environment in the livestock facilities, It is important to secure monitoring data of the thermal environment and the concentration of harmful gases and fine dust. Multi-point measurement was performed to analyze the regional environmental conditions in the pig rooms. When analyzing the working environment, video monitoring was conducted to analyze the concentration changes of ammonia, hydrogen sulfide and fine dust according to worker movement and work type. Ammonia and hydrogen sulfide monitoring result showed 1.5~2 times higher concentrations than other work when working in the pigs living zone, and 2~4 times higher than other work when working to increase the activity of pigs. In the case of fine dust, the result was 1.3 times higher than the worker's exposure standard in a specific work. The concentrations of gases and dusts from pig farms are not of concern for acute poisoning in normal work, but there is a risk of chronic respiratory disease if they are continuously exposed. Accordingly, there is a need for development of work environment monitoring device tailored to workers and preparation of alternatives.

• The Journal of the Korea Contents Association
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• v.16 no.12
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• pp.170-180
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• 2016

Objectives: While the proportion of the non-regular workers youth increases in labor market, the differential conditions of temporary employee are increased. Methods: Research objects were 4,322 youth (from 15 to 29) among members of workers who responded to 2014 PSWCI panel report. Statistical analyses were performed using the SAS version 9.4 (SAS Institute Inc., Cary, NC, USA). Data were analyzed using frequency test, t-test, ANOVA and multiple regression. Results: According to results of analysis, youth had differences in youth temporary workers, working conditions, classification of occupation, working period, and health conditions based on work-time conditions. Conclusions: Youth workers, policies on working hours will need to take steps toward reducing working hours and improve a health promoting hierarchy for work environment.

• Journal of Preventive Medicine and Public Health
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• v.26 no.1 s.41
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• pp.20-36
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• 1993

Work-related low back pain is one of the major factors that cause the loss of working power especially in actively working age, therefore controlling the work-related low back pain is one of the major issues in the field of industrial safety and health. This study was performed for detecting the risk factors and proposing the efficient control program of the work-related low back pain. The subjects were male workers employed at the manufacturing industry in Pusan with longer than 6 months' working duration. The data was collected by self-reported questionnaire and interview from May 1 to October 31,1992. The contents of questionnaire were as follows:. the experience of low back pain within the recent one month, general characteristics(age, marital status, education level, religion, regular exercise), physical characteristics(height, weight), employment status(working duration, daily working hours, rest during work, satis(action fur the job), type of work and working environments(posture, forward bending, lifting and movement, satisfaction for table and chair). The result was analyzed for 608 entire respondents by case-control comparative method. The number of cases was 152 with a history of work-related low back pain, so the relative frequency of self-reported work-related low back pain was 25.0%, and the number of controls was 344 without any history of low back pain. As a result, two characteristics of the employment status(working duration, satisfaction fur the job) and all characteristics of type of work and working environments showed a statistical significance between the case and control groups(p<0.01). The Oddb ratios of these variables for Work-related low back pain were calculated. They were 7.88 for the satisfaction fur chair, 7.86 for lifting and movement,3.31 for satisfaction for table, and 2.22 fur bending forward(p<0.01). And for the multivariate logistic regression analysis confirmed that unsatisfaction for table was independent risk factor for Work-related low back pain. In summary, though this study was based upon the self-reported questionnaire and the subjective complaints, the satisfaction for chair, lifting and movement, satisfaction for table, and bending forward concerned with the type of work and working environments were considered as the main factors causing the work-related low back pain, and the work-related low back pain may be preventable by the ergonomic control of these factors.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.05a
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• pp.234-237
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• 2007

To protect a satellite and electronic equipment from the acoustic load generated by rocket propulsion system, many launch vehicle use acoustic blanket. Acoustic load is main source of random vibration working on the payload. Most high frequency region of the acoustic loads is reduced by payload fairing skins and acoustic blanket, but low frequency region is not. In order to reduce acoustic load of low frequency region, we designed array resonator panel which was made of composite materials. Insertion loss capacity of the payload fairing with acoustic blanket was verified from PLF acoustic test in the acoustic chamber.

• Progress in Superconductivity and Cryogenics
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• v.3 no.2
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• pp.49-54
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• 2001

The purpose of this study is to analyze the characteristics of the linear compressor for Stirling refrigerator. To ensure high performance and long life of the FPFD(Free Piston. Free Displacer) type Stirling refrigerator, the operating parameters of the linear compressor should be optimized. The experimental results show that the operating frequency of the linear compressor has significant effect on the input power characteristics. and that the compressor with higher charging pressure of working fluid has high pressure ratio. For the high performance of the linear compressor. compressor should be operated at the resonance frequency with respect to the given charging pressure.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.591-595
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• 1997

In analysis of piping vibration of petrochemical plant, the forcing functions mainly depend upon the equipment working mechanism and vibration resources in the piping systems. In general, harmonic function is used for the system with rotary equipments. Mechanical driving frequencies, wave functions, and response spectrum are used for reciprocating compressors, surge vibration of long transfer piping, and seismic/wind vibration, respectively. In this study, for the spray injection case inside the pipe, forcing function was modeled, in which two different fluids are distributed uniformly. To confirm the results, the scheme used for the forcing function was applied for real piping system. The vibration mode of the real system was consistent with the 4th mode obtained by simulation using the forcing function formulated in this study.

• 제어로봇시스템학회:학술대회논문집
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• 1987.10b
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• pp.370-375
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• 1987

Damping piston with an orifice in the piston head is utilized to improve the damping characteristics of a pneumatic push-push type rotary actuator. Through linearized analysis, the optimum size of orifice, which gives maximum damping effect at the frequency where damping is desired. most, is predicted. The frequency response test of teal system were carried out to see the effects of damping piston and to obtain true optimum size of orifice by trying orifices of various size near the predicted value. During the tests, both air and helium were tried as working fluid, and a lag-lead compensation circuit was incorporated to improve system dynamics. The finally chosen orifice size is a little bigger than that predicted from analysis, however it gives high damping effects for the finally designed pneumatic system enough to have wide frequency response bandwidth.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.1026-1031
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• 2003

A vibration isolation system fur a large reverberation chamber (1,228㎥, 1,000ton) has been installed. The reverberation chamber generates loud noise and induces high level of vibration to perform spacecraft acoustic environmental tests. The isolation system prevents vibration transfer from the chamber to enclosure buildings. This paper describes logical design process and commissioning experiments of the system. Design criteria have been induced from rigid body model of the chamber. Finite element model has been employed to select the characteristics of rubber pads. A total of 21 rubber pads have been installed between the chamber and supporting pedestals. A sand bag of 800kg was dropped on the chamber floor to measure the natural frequency of the isolation system. Absolute transmissibility has been measured while generating 145㏈ in the chamber. The natural frequency of the chamber is 10.5㎐, which is 80% of estimated value. Overall transmissibility at working frequency range (25㎐-10,000㎐) is less than -6㏈.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.627-632
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• 2002

The paper considers acoustic analysis of the shock absorbing muffler within a rotary compressor. The internal space of the compressor is modelled as a combination of cavities and pipes. A simple one-dimensional impedance approach is used fur the acoustic analysis in the low frequency range, with ignoring the effects of gas flow and temperature gradients that are closely related to power efficiency of the compressor. Using the similarity between the vibration isolator and the shock absorbing muffler, the source strength transmissibility is newly proposed as a performance measure of the muffler and its validity is supported by power analysis. Some Important muffler design rules obtained are; (1) a muffler cavity and its opening throat should be used as a pair, (2) a long thin throat is desirable for high frequency noise isolation, (3) a large muffler cavity should be used with care since it shortens the working frequency range of the muffler. The rules were applied to redesign a compressor muffler currently in use, and a significant improvement was achieved by simply attaching a throat to the outlet holes of the muffler.