• Journal of the Korean Society of Safety
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• v.27 no.3
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• pp.131-140
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• 2012

Though there might exist not a few differences between cyclic works and atypical works, many researchers have applied the same assessment techniques that used for repetitive works, which may result introduce bias in their conclusions. This research aimed to verify whether there exist non-negligible work characteristics and/or dissimilarity among works with different work nature and whether one of the most prevalent assessment techniques for assessing ergonomic hazards of musculoskeletal disorders, REBA, can be applied to atypical works. For a general hospital, an automobile repair shop, and two auto-part assembly plants which manufactures quite different parts, a questionnaire survey and field investigation and ergonomic assessment were carried out and analyzed statistically with reference to the 3rd Quantification technique. The results showed that there exist remarkable difference between physical factors in cyclic works and atypical non-cyclic works. As for repetitive work, body posture was significant factors affecting on musculoskeletal disorders while atypical works seemed to have none which implied that the necessity of taking psychosocial factors into account for assessment of hazards. Complain rate in repetitive works was highest shoulder, back, and neck or wrist in sequence. However, there existed no consistent trend in complain rate in atypical works. And, though weight of manufacturing objects was a common factor that can partly explain musculoskeletal complain, time duration was significant in atypical work whereas repeatability and body posture were significant in repetitive works. As being the results, to summarize, it could be said that application of conventional ergonomic assessment techniques regardless of repetitiveness would be fruitless, and that the necessity of a unique methodology focused on atypical non-cyclic works should not be neglected.

• Journal of Korean Tunnelling and Underground Space Association
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• v.4 no.1
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• pp.57-70
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• 2002

Since early in the 90's, the need for construction of underground rock structures such as long and large section traffic tunnel, energy storage cavern, industrial facility, etc. has been largely increased because the Korean territory is not wide and about 65 % of the land consists of mountainous region. The initial rock stress measurement has been widely conducted to provide the quantitative information on the stress state of engineering site at the design stage of underground rock structures. Among the diverse methods developed for measuring rock stress, hydraulic fracturing test is most popularly used because it is applicable at pre-construction stage and has no limit in testing depth. In this paper, the characteristics of initial rock stress state in mountainous region were studied on the basis of the in-situ hydraulic fracturing stress measurement results from the 60 test boreholes in various parts of Korea.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.29 no.5
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• pp.259-268
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• 2017

This paper proposes a hydrogen-based social economy derived from fuel cells capable of replacing fossil fuels and resolving global warming, It thus provides an entry for developing economically feasible social configurations to make use of bio-hydrogen production systems. Bio-hydrogen production works from the principle that microorganisms decompose water in the process of converting CO to $CO_2$, thereby producing hydrogen. This study parts from an analysis of an existing 157-ton class NA1 bio-hydrogen reactor that identifies the state of feedstock and reactor conditions. Based on this analysis, we designed a 1-ton class bio-hydrogen reactor process simulator. We carried out thermal analyses of biological heat reactions, sensible heat, and heat radiation in order to calculate the thermal load of each system element. The reactor temperature changes were determined by modeling the feed mixing tank capacity, heat exchange, and heat storage tank. An analysis was carried out to confirm the condition of the feed mixing tank, heat exchanger, heat storage tank capacity as well as the operating conditions of the system so as to maintain the target reactor temperature.

• Spatial Information Research
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• v.3 no.1
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• pp.39-46
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• 1995

Rural water resources systems may be largely constituted by two parts. One is rural water supply systems such as reservoirs, wells, pumping stations. The other is rural water demand systems which include municipal water, irrigation water, industrial water, livestocks water, inland fisheries water and envir¬onmental water in rural areas. planning to develop rural water resources systems is a very hard task because of their complicated factors and the large number of spatial data to investigate and manipulate. A Geographic Information SystemCGIS) will be a powerful and efficient tool to handle the spatial data and to plan the land use. All data can be efficiently maintained and easily updated. This paper refers to the construction of a GIS for planning rural water resources systems applied to Kokseong County, Cheonnam Province, Republic of Korea. The Geographic Informa¬tion was constituted by 4 layers of base map and 11 layers of thematic map.

• Korean Business Review
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• v.15
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• pp.99-114
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• 2002

Recently several business models concerning e-Business has been introduced. But the different environment for each business requires the business model which is contingent to its specific situation. We, therefore, need to develop the e-Business models considering environment factors such as capital size, technology level, collection ability and amount of information, profit or target customers, etc. There can be several ways to create the value of an e-Business firm. A way among them is to develop limited area by focusing on core parts of the firm. This way leads for the firm to search the investment priority in order to solve the problem, which is to set a proper production and investment level for concentrating on competitively excellent areas of the firm. In this paper, we propose a method to decide the investment priority effectively when making a decision using fuzzy information. The method by our model is to minimize tolerances of given business fuzzy goals.

• Korean Journal of Materials Research
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• v.21 no.6
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• pp.320-326
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• 2011

Flat rolling of wire is an industrial process used to manufacture electrical flat wire, medical catheters, springs, piston segments and automobile parts, among other products. In a multi-step wire flat rolling process, a wire with a circular crosssection is rolled at room temperature between two flat rolls in several passes to achieve the desired thickness to width ratio. To manufacture a flat wire with a homogeneous microstructure, mechanical and metallurgical properties with an appropriate pass schedule, this study investigated the effect of each pass schedule (1stand ~ 4stand) on the microstructures, mechanical properties and widths of cold rolled high carbon steel wires using four-pass flat rolling process. The evolutions of the microstructures and mechanical properties of the widths of cold rolled wires during three different pass schedules of the flat rolling process of high carbon wires were investigated, and the results were compared with those for a conventional eight-pass schedule. In the width of cold rolled wires, three different pass schedules are clearly distinguished and discussed. The experimental conditions were the same rolling speed, rolling force, roll size, tensile strength of the material and friction coefficient. The experimental results showed that the four-pass flat cold rolling process was feasible for production of designed wire without cracks when appropriate pass schedules were applied.

• Safety and Health at Work
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• v.8 no.1
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• pp.84-88
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• 2017

Background: Workers in slaughterhouses are exposed to a wide range of biological contaminants, such as bacteria and fungi, due to their working environment. This study aimed to assess the prevalence of respiratory disorders among workers in slaughterhouses. Methods: This study was conducted on 81 workers in slaughterhouses and 81 healthy office workers as a reference group. The American Thoracic Society standard respiratory symptoms questionnaire was used to determine the prevalence of respiratory disorders. Besides, lung function tests were conducted using a calibrated spirometer at the beginning (preshift) and at the end (postshift) of the $1^{st}$ working day. Single-stage Anderson sampler was used to measure the concentration of bioaerosols in different parts of slaughterhouses. Results: The prevalence of respiratory disorders, such as cough, productive cough, breathlessness, phlegm, and wheezing, was 3.17, 4.02, 3.07, 4.66, and 3.94 times, respectively, higher among workers in slaughterhouses compared with the reference group. Conclusion: The prevalence of respiratory disorders was significantly higher among workers in slaughterhouses. Thus, the significant reduction in the percentage predicted lung function among workers in slaughterhouses might be associated with exposure to bioaerosols in their work environment.

• Journal of the Korea Society of Computer and Information
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• v.8 no.3
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• pp.188-196
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• 2003

The hazardous enterprise has been increasing its relative importance day by day in the economy of our country and the world. However, it's mostly true to have been relatively neglected in the field of technical strategy. This is to provide for methodological frame about the research in this field in the future by researching on what kind of technical and marketing strategies make what kind of effect on the result of hazardous enterprise together with the strategy for success by meeting the necessity of this research. Therefore, the individual variable within this research was divided into three parts like technical strategy, marketing strategy and industrial environment. It used the type division of venture-company(High-tech type, Superior enterprise type, Boutique type, General enterprise type) as a controllable variable and the result of hazardous enterprise as a subordinate variable. The result of this research is that the technical strategy of hazardous enterprise has lots of possibilities to raise the financial result if it raises technical reform and supplementary character and technical integration level in case that newly-established hazardous enterprise with relatively lower capital power than big enterprise pursues technical strategy.

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.6
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• pp.84-92
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• 2005

This paper is concerned with optimum design of a center-pillar assembly induced by the high-speed side impact of the vehicle. In order to simulate deformation behavior of the center-pillar assembly, simplified finite element model of the center-pillar and a moving deformable barrier are developed based on results of the crash analysis of a full vehicle model. In optimization of the deformation shape of the center-pillar, S-shaped deformation is targeted to guarantee reduction of the injury level of a driver dummy in the crash test. Tailor-welded blanks are adopted in the simplified center-pillar model to control the deformation shape of the center-pillar assembly. The thickness of each part which constitutes the simplified model is selected as a design parameter. The thickness of parts which have significant effect on the deformation mechanism are selected as design parameters with sensitivity analysis based on the design of experiment technique. The objective function is constructed so as to minimize the weight and lead to an S-mode deformation shape. The result shows that the simplified model can be utilized effectively for optimum design of the center-pillar members with remarkable saving of computing time.

• International Journal of Precision Engineering and Manufacturing
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• v.8 no.2
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• pp.38-43
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• 2007

This paper describes ultrasonically assisted grinding used to obtain a glossy surface quickly and precisely. High-quality surfaces are required for plastic injection molding dies used in the production of plastic parts such as dials for cellular phones. Traditionally, in order to finish the dies, manual polishing by a skilled worker has been required after the machining processes, such as electro discharge machining (EDM), which leaves an affected layer, and milling, which leaves tooling marks. However, manual polishing causes detrimental geometrical deviations of the die and consumes several days to finish a die surface. Therefore, a machining process for finishing dies without manual polishing to improve the surface roughness and form accuracy would be extremely valuable. In this study, a 3D positioning machine equipped with an ultrasonic spindle was used to conduct grinding experiments. An electroplated diamond tool was used for these experiments. Generally, diamond tools cannot grind steel because of excessive wear as a result of carbon atoms diffusing into bulk steel and chips. However, ultrasonically assisted grinding can achieve a fine surface (roughness Rz of $0.4{\mu}m$) on die steel without severe tool wear. The final aim of this study is to realize mirror surface grinding for injection molding dies without manual polishing. To do this, it is necessary to fabricate an electroplated diamond tool with high form accuracy and low run-out. This paper describes a tool-making method for high precision grinding and the grinding performance of a self-electroplated tool. The ground surface textures, tool performance and tool life were investigated A ground surface roughness Rz of 0.14 um was achieved Our results show that the spindle speed, feed rate and cross feed affected the surface texture. One tool could finish $5000mm^2$ of die steel surface without any deterioration of the ground surface roughness.