• Journal of Korean Institute of Industrial Engineers
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• v.24 no.4
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• pp.639-647
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• 1998

We consider a multiclass production system processed by a single machine with cyclic order. Each part belongs to one of several classes and arrives at each queue in a Poisson process. The processing discipline at each queue is either exhaustive or gated. We introduce a new approach to analysis of mean waiting times for each queue. We formulate mean waiting times as cost functions on state of the system. The mean waiting times are obtained by solving a set of O($J^2$) linear equations, where J is the number of queues in the system. We also obtain the mean number of parts of each queue in the system at an arbitrary time. Based on this result, we plot the numerical values of the mean waiting times for several parameter settings.

• IE interfaces
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• v.13 no.4
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• pp.639-645
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• 2000

Virtual manufacturing systems that perform production activities ahead of real production in virtual world can reduce time and cost to develop, design, plan, and manage new products. In this paper, a virtual manufacturing system is constructed as a tool to support decision making by using VRML and Java. The basic structure of the virtual manufacturing system and the operation models are also presented. The developed system helps any related persons to share design and manufacturing information, and to perform their tasks collaboratively through Internet. The other function of the system is to monitor operation status in real time.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.400-403
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• 2004

In conventional methods, the availability of floating crane has determined the size of a concrete caisson. However, this paper introduces a new method for larger caisson production that make it possible to complete caisson fabrication and launch out without use of floating crane. The new method carries out multi-step fabrication of caisson and horizontal transfer of caisson on a single casting bed which consists of collapsible soffit form, trough, aero go watercaster system or low frictional PTFE added jacking system, half-submergible floating dock. To make the new method successfully launched, the static and dynamic analysis is carried out to obtain the stability of caisson launching and experimental research is conducted in evaluating friction occurred between PTFE pad and steel track. Lastly, the comparison of the new method and the conventional method are detailed. With significant benefits in construction costs reduction and construction time reduction, this new method in this paper would be recommended for extensive application in large port and harbor construction projects.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.2
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• pp.327-332
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• 2008

New RF matcher module has been proposed in this paper for improvement of RF matcher in plasma etcher system using in semiconductor and display panel manufacturing process. New designed warm gear was used instead of bevel gear in new driving module, and control system was re-arranged with one-chip micro-process technique. The matching performance of new match module was improved in various process condition with reduction of backlash and matching time, and flexible motion of motor compared commercial match module. However this new type RF match module will improve the productivity in etching process of the mass production line.

• Journal of People, Plants, and Environment
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• v.21 no.6
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• pp.493-500
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• 2018

The distribution of standing wreaths has reached about 7.1 million per year and the size of the standing wreath market is estimated to be at least 700 billion won. Among them, 20 to 30 percent are estimated to be reused, resulting in damage to flowerfarms' sales of 110 to 160 billion won per year. Due to the unique characteristics of conventional 3-tier standing wreaths in terms of transportation and installation, companies that lack design expertise have monopolized local distribution markets, and the issue of illegally using standing wreaths has been raised. These issues have highlighted the need for developing new designs and establishing a distribution system to expand the consumption of flowers. This study was carried out to identify consumers' perception of reused standing wreaths and the current systems introduced to prevent the distribution of reused standing wreaths such as the real-name standing wreath production system, the authenticity certificate system, and new standing wreaths. The results of a consumer survey showed that consumers' perception of reused standing wreaths has been high and that reused standing wreaths need to be actively regulated to establish fair trade order and protect consumers' rights. Although the effectiveness of the real-name system, the authenticity certificate system, and new standing wreaths was found to be insufficient, the introduction of these systems was essential and necessary for continuous promotion through broadcasting media.

• Proceedings of the KAIS Fall Conference
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• 2001.11a
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• pp.173-176
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• 2001

A company needs to maintain its machines always workable in order to keep the manufacturing time minimal. If any troubles un, they should be fixed as soon as possible. But, the complexity of modem machines make the trouble shooting difficult. So, it is important that the monitoring system for automated production system to fix every trobule easily. In this paper new, inverter control system for TG feedback a formula Control was developed. The motor control system with TG feedback controller as an effect of load disturbance, it is very difficult to guarantee the robustness of Control System. The function of the implementation are TG feedback type, and temperature scheme. The Inverter Control System approach is based on master-slave control concept. To show validity of the developed new inverter control system severial experiments are illustrated.

• New & Renewable Energy
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• v.20 no.1
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• pp.145-174
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• 2024

Addressing climate change necessitates evidence-based policies grounded in science. The use of forest biomass for energy production is based on a broad scientific consensus at the international level. However, some environmental groups in South Korea are opposing this system of energy production. Through this study, the authors aim to reduce unnecessary confusion and foster an atmosphere conducive to meaningful evidence-based policies. We have classified the issue into eight categories: biological carbon cycle, carbon debt, nature-based solutions, air emissions, cascading principles and sustainability certification, forest environmental impacts, climate change litigation, and the behavior of environmental groups and public perception. Consequently, the following key points were derived: (1) the actions of some environmental groups seem to follow a similar pattern to denialist behavior that denies climate change and climate science; (2) the quality of evidence for campaigns that oppose the use of forest biomass for energy production is low, with a tendency to overgeneralize information, high uncertainty, and difficulty in finding new claims.; (3) most of the public believes that forest biomass energy is necessary, and the governments of major countries are aware of its importance. Significantly, Forest biomass for energy is based on an overwhelming level of scientific consensus recognized internationally.

• Journal of Hydrogen and New Energy
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• v.9 no.1
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• pp.38-45
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• 1998

An energy crisis is expected in near future. Fossil fuel such as oil and natural gas has been used and will be no longer supplied enough to demand in the beginning of coming century. The use of the fuel makes a lot of environmental pollution to threaten human being's health especially in big cities and produces a lot of $CO_2$ to make green house effect of the earth. It is the time to use clean fuel such as hydrogen to prevent the expected energy crisis and the pollution. A new engine such as fuel cell can be used instead of the conventional internal combustion engine with 2 to 3 times higher efficiency of the conventional engine. The fuel cell uses hydrogen and oxygen and produces electric energy and pure water, which is a calm engine without air pollution. In big cities the city buses and the taxies powered by hydrogen fuel cells are suggested to be operated for clean environment. A model of the total energy system for production, transportation and utilization of hydrogen is calculated.

• The Journal of the Korea Contents Association
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• v.10 no.8
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• pp.159-167
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• 2010

Since success of in the box office, there are not only highly interested in 3D Stereoscopic in Media market but also has been briskly supporting for 3D Stereoscopic producing in variety platforms including film, broadcasting, mobile They expect 3D Stereoscopic will be a new standard format for media of domestic market as well as overseas. However there are required professional production system and grant capital for 3D Stereoscopic production. In case of domestic industry, there are not forged through specialized production system and lack of 3D Stereoscopic producing. They are needed not only Pipeline for 3D Stereoscopic production but also strategic supporting like specialized education and test-bed for 3D Stereoscopic production. It is able to established efficient and specialized system for 3D Stereoscopic production given the pipeline proposal.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.59 no.4
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• pp.377-386
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• 2023

As discarded fishing gear settles or floats on the seabed, it destroys the spawning and habitat of fisheries resources that causes various safety accidents and adverse effects on the environment, such as generating microplastics and causing ship accidents. In order to solve this problem, this study is intended to present an implementation plan for establishing a fishing gear deposit system in order to use it as basic data for establishing policies for fishing gear management in Korea. In order to successfully implement the fishing gear deposit system, the deposit system must be established in the form of fishing gear completed at the production stage. It was found that the marking of the object should be easy, and that determining an appropriate deposit amount to motivate the return of waste fishing gear and establishing a convenient return procedure for returned waste fishing gear were important factors. In addition, transparent management of unreturned deposits and mandatory use of fishing gear subject to the deposit system for fishermen will be necessary. The role of a specialized organization to manage and operate all of these procedures is also very important. It is necessary to establish a new mandatory provision in the Fisheries Act to require fishermen who directly use fishing gear to use fishing gear with a deposit refund mark, and to ensure the implementation of the deposit system by linking it with the evaluation items of government policy projects. Since the main purpose of the deposit system is to collect discarded fishing gear, a support plan will be necessary in accordance with the purchase project for fishing waste salvaged by local governments in 2020.