• Journal of Korean Institute of Industrial Engineers
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• v.34 no.1
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• pp.98-107
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• 2008

The purpose of this paper is to present an optimization scheme that aims at minimizing the expected cost per unittime. This study considers a linear connected-(r, s)-ouI-of-(m, n):f lattice system whose components are orderedlike the elements of a linear (m, n)-matrix. We assume that all components are in the state 1 (operating) or 0(failed) and identical and s-independent. The system fails whenever at least one connected (r, s)-submatrix offailed components occurs. To find the optimal threshold of maintenance intervention, we use a simulatedannealing(SA) algorithm for the cost optimization procedure. The expected cost per unit time is obtained byMonte Carlo simulation. We also has made sensitivity analysis to the different cost parameters. In this study,utility maintenance model is constructed so that minimize the expense under full equipment policy throughcomparison for the full equipment policy and preventive maintenance policy. The full equipment cycle and unitcost rate are acquired by simulated annealing algorithm. The SA algorithm is appeared to converge fast inmulti-component system that is suitable to optimization decision problem.

• Journal of Navigation and Port Research
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• v.28 no.7
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• pp.587-591
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• 2004

In order to measure the performance of resources in a port container terminal, we conducted a state transition network simulation to model various equipment processes. The processes that container cranes and transfer cranes perform are idle, wait, move, and work. Vehicles perform idle, wait, empty travel, and full travel. Because cranes, vehicles, and vessels are movable entities and all equipment is classified as either a customer or server, we separated the various stages of the process based upon the state transition network To validate the simulation results, a real system was used to illustrate the use of various measurements using the state transition network.

• Journal of Welding and Joining
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• v.34 no.4
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• pp.9-16
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• 2016

Metal parts are produced by conventional methods such as casting, forging and cutting, extrusion, etc. However, nowadays, with additive manufacturing (AM), it is possible to directly commercialize by means of stacking of equipment to the 3D drawing and use of high precision tools such as laser source. Thus, drawing of materials is an important aspect in delivering good products. AM deals with production of lighter aircraft parts and few more three-dimensional molds, it wish to manufacture special medical parts and want to steadily expand the new market area. The cost of related equipment and materials are still expensive and difficult to obtain on a mass production. However, the ability to make changes and lead the innovation in the paradigm of traditional manufacturing process is still effective. In this paper, we introduce metal AM and the principles of the related devices, metal powder production process, and their application.

• Safety and Health at Work
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• v.13 no.4
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• pp.440-447
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• 2022

Background: Agricultural handle equipment is present on all production areas' farms. They are handy and portable; however, excessive use can lead to acute traumas or accidental injuries. Repetitive movements, awkward postures, and hand-arm vibrations predispose them to pain and work-related musculoskeletal disorders. The purpose of this study was to observe the interaction of handle equipment in terms of electromyographic activity and analyze the postural work-related alterations. Materials and methods: Twenty male agricultural operators, mean age 24±1.54 years, underwent the electromyographic analysis testing their muscular activities with a brushcutter, electric saw, and hedge trimmer in four different test conditions. Results: The brushcutter proved to be the agricultural handle equipment with the higher mean frequency (3.37±0.38 Hz) and root mean square (5.25±1.24 ms^-2). Furthermore, the digital postural analysis showed a general asymmetry of the main arm and the respective side of the trunk. The head resulted right inclined in the anterior frontal plane by 5.7°±1.2°; the right scapula lower than the left in the posterior frontal plane (8.5°±1.8°), and a working trunk inclination of 34.15°±5.7°. Conclusions: Vibrations of handle equipment and awkward working postures represent a risk for agricultural operators. Preventive measures are required to avoid young operators from experiencing musculoskeletal disorders all lifelong.

• Journal of Navigation and Port Research
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• v.29 no.1 s.97
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• pp.91-96
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• 2005

The National Marine Electronics Association(NMEA) is nonprofit-making cooperation composed with manufacturers, distributors, wholesalers and educational institutions. We use the basic port of equipment in order to process the signal from NMEA signal using equipment. When we don't have enough one, we use the multi-port for processing. However, we need to have module development simulation which could multiplex and provide NMEA related signal that we could solve the problems in multi-port application and exclusive equipment generation for a number of signal. For now, we don't have any case or product using NMEA multiplexer so that we import expensive foreign equipment or embody NMEA signal transmission program like software, using multi-port. These have problems since we have to pay lots ci money and build separate processing part for every application programs. Besides, every equipment generating NMEA signal are from different manufactures and have different platform so that it could cause double waste and loss of recourse. For making up for it, I suggest the NMEA multiplexer embodiment, which could independently move by reliable process and high performance single hardware module, improve the memory efficiency of module by designing the optimized Queue, and keep having reliability for realtime communication among the equipment such as main input sensor equipment Gyrocompass, Echo-sound, and GPS.

• Architectural research
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• v.8 no.2
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• pp.43-48
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• 2006

The appropriate fleet estimation of the excavation equipment is a major factor in the determination of the cost and time requirements of a project. But the decision of what kind of equipment selected is often based on heuristic methods or trial and error in Korea. Thus, this study proposes a prototype model that uses genetic algorithms to select fleet estimation of loaders (backhoe) and trucks used in excavation work. To verify the applicability of this model, the case study was performed. And the result of the genetic model was compared with that of the trial & error method. The use of the genetic model suggested this study required 44days, 2 units of backhoes, 7 units of trucks, and a total cost of 171,839,756 won. With the estimated fleet number of equipment, the minimum cost of excavation work can be calculated, taking account of the time-cost trade-off. By utilizing this prototype model, the efficiency of excavation work can be improved.

• Safety and Health at Work
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• v.4 no.3
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• pp.136-141
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• 2013

Background: Occupational end users of pesticides may experience bodily absorption of the pesticide products they use, risking possible health effects. The purpose of this paper is to provide a guide for researchers, practitioners, and policy makers working in the field of agricultural health or other areas where occupational end use of pesticides and exposure issues are of interest. Methods: This paper characterizes the health effects of pesticide exposure, jobs associated with pesticide use, pesticide-related tasks, absorption of pesticides through the skin, and the use of personal protective equipment (PPE) for reducing exposure. Conclusions: Although international and national efforts to reduce pesticide exposure through regulatory means should continue, it is difficult in the agricultural sector to implement engineering or system controls. It is clear that use of PPE does reduce dermal pesticide exposure but compliance among the majority of occupationally exposed pesticide end users appears to be poor. More research is needed on higher-order controls to reduce pesticide exposure and to understand the reasons for poor compliance with PPE and identify effective training methods.

• Journal of The Korean Association For Science Education
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• v.22 no.5
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• pp.957-969
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• 2002

Theoretical benefits and research findings on the use of Microcomputer-based Laboratory (MBL) are considered for using MBL in a way that will be of benefit to students and teachers, and discussed as a whole for further synthesis, including the formulation of a research agenda for future consensus-based action. Based on the findings obtained from a comprehensive review of the literature, using a systematic approach, the uses of MBL were compared and contrasted for advancing understanding of the teaching and learning processes in science and mathematics. A number of benefits were proposed by MBL developers but not investigated by educational researchers. A few research studies considered the following practical aspects raised by classroom science teachers: technical problems of MBL equipment; inaccuracy or incompleteness of presentation; efficient ways for handling class time with MBL instruction; and development of MBL curriculum materials for their own instruction. This lack of research related to the use of MBL in science classrooms resulted in educational research that was neither respected nor utilized by science teachers. Setting a research agenda based on the theoretical benefits and research findings is necessary for the effective use of MBL in science classrooms can help to maximize the prospects for successful school improvement projects while minimizing the innovation-related frustrations of individuals.

• Journal of Distribution Science
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• v.12 no.1
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• pp.5-12
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• 2014

Purpose - The general objective of this study is to explain the governance mechanisms of relational exchanges by considering both economic and relational factors. As regards the relationship between opportunism and governance mechanisms, opportunism was hypothesized as being positively related to the use of the authority mechanism, and negatively related with use of the trust mechanism. Research design, data, and methodology - Purchasing relationships between original equipment manufacturers (OEMs) and their component suppliers were chosen as the empirical setting. Purchasing specialists in each company, who interact regularly with suppliers and have the major responsibility for managing the exchange relationships with suppliers, were used as the respondents for this study. A mail survey methodology was employed to collect data in the final field survey. Results - As predicted, opportunistic behavior is found to be negatively related to the use of the trust mechanism and positively related to the use of the authority mechanism. Therefore, the result supports the proposed hypotheses. Conclusions - By integrating research streams, this study contributes to the marketing discipline by improving our understanding of when and why different mixtures of governance mechanisms are used.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.23 no.3
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• pp.212-221
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• 2013

Objectives: Asbestos fibers are accumulated in negative pressure unit (NPU) or vacuum cleaner in asbestos removal. Failure of operation or poor use performance of the NPU or vacuum cleaner causes asbestos fibers to spread in the air. Asbestos contractors should have an NPU fitted with a HEPA , vacuum cleaner, decontamination area, respirators, wetting equipment, and differential pressure manometer to register with the Ministry of Employment and Labor. There should be performance criteria of equipment used in asbestos removal. But there are none such criteria used in asbestos removal. This study was performed to investigate international or national performance criteria of equipment used in asbestos removal. Methods: Regulations, approved code of practice, guidance and national standards of the UK, USA and Korea were reviewed. A survey was done to investigate the requirements for equipment used in asbestos removal in Korea. Results: Air flow of NPUs used in Korea usually covers from$500m^3/h$ to over $3000m^3/h$. Some requirements for NPUs used in Korea were missing compared to the requirements of British standards for NPUs. All NPUs have different missing requirements. The UK also has separate British standard for leak tests for NPUs. Highly hazardous class vacuum cleaners should be used in asbestos removal in the UK. It has national standards on the operation of vacuum cleaners used in asbestos removal. There is only a certification system for less than 2.5kw rated voltage vacuum cleaners for home use in Korea. Powered (-assisted) respirators with mask are recommended in asbestos removal. Type 5 coveralls should be used in asbestos removal in the UK. There are international standards for requirements and leak tests of type 5 coveralls. A manometer for measuring differential pressure is needed in asbestos removal. The manometer's measuring range should cover less than ${\pm}125$ Pa and the gradation of manometer should be less than 2.5 Pa. The definition of decontamination area should be corrected. Installation of airlock and minimum area should be considered in decontamination area. Conclusions: Equipment should be used in asbestos removal proper performance and no leaks. There should be a certification system for equipment used in asbestos removal. This study can help to a certification system for equipment used in asbestos removal in Korea.