• Journal of agriculture & life science
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• v.44 no.6
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• pp.191-199
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• 2010

How to determine rental rates of agricultural machinery operation is the most important factor for economic units which are consigned to practice agricultural operations. Economic units as consigner for agricultural operations include agricultural cooperatives, local government, and farm operators, and so on. Thus the methods to set a rental rate of agricultural machinery operation are different across these economic units. This study describes benefits and problems associated with the model of cost accounting which is used as a method to determine a rental rate of agricultural machinery operation, and suggests a theoretical desirability of the rental pricing method, based on an accounting system and information on costs.

• Progress in Superconductivity and Cryogenics
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• v.11 no.3
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• pp.26-30
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• 2009

Korea Superconducting Tokamak Advanced Research(KSTAR) device is composed of 30 superconducting magnets, magnet structure, vacuum vessel, cryostat, current feeder system, and etc. KSTAR device is operated in the cryogenic temperature and high magnetic field. We install about 800 sensors - temperature sensors, stain gages, displacement gages, hall sensors - to monitor the thermal, mechanical, electrical status of KSTAR during operation. As a tremendous numbers of sensors should be installed for monitoring the KSTAR device, the method of effective installation was developed. The sensor test was successfully carried out to check its reliability and its reproduction in the cryogenic temperature. The sensor signal is processed by PXI-based DAQ system and communicated with central control system via machine network and is shown by Operator Interface(OPI) display in the main control room. In order to safely operate the device, any violations of mechanical & superconductive characteristic of the device components were informed to its operation system & operator. If the monitored values exceed the pre-set values, the protective action should be taken against the possible damage. In this paper, the system composition, operation criteria, operation result were presented.

• Journal of the Korean Society of Industry Convergence
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• v.26 no.6_2
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• pp.1109-1115
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• 2023

The shell and tube-type heat exchanger was the most utilized in industrial field because of its simple structure and wide operation conditions and so on. This study was performed to investigate the characteristics of behavior of thermal flow according to operation condition of small-sized shell and tube-type heat exchanger. The operation conditions, here, were set up to flow rate of hot air with temperature of 100℃, number of baffle and cut rate of baffle(BCR) using numerical analysis. As the results, both mean relative pressure and relative pressure drop was increased with quadratic curve in case of less than BCR 25%, however, decreased linearly in case of more than BCR 25%. The collision with first baffle by flow velocity and temperature, of hot air, respectively, was depended on BCR. Further it showed that the behaviors between flow velocity and temperature were almost similar.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.1241-1245
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• 2011

High RAM performance and efficient operation plan and maintenance equipment and policies are needed for improving the system availability performance such as punctuality and schedule adherence while reducing life cycle cost. Because railway systems are repairable, complex and have multi-echelon maintenance support structure, it is much complicated to set RAM performance targets and operation and maintenance plan. It is not easy to solve these problem by mathematical method and simulation can be consider for them. This article suggests the conceptual simulation model for analysing availability of railway system which has complex system structure and operation/maintenance environment.

• The KSFM Journal of Fluid Machinery
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• v.15 no.3
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• pp.51-56
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• 2012

This study analyzed the influence of firing biogas on the performance and operation of a gas/steam turbine combined system. A reference gas/steam turbine combined system, designed with biogas fuel(57% volumetric methane) was set up and off-design simulation was made to investigate operating characteristics when a couple of operating schemes to mitigate turbine blade overheating were applied. Performance at base-load operation using each scheme was compared and part load operation using the variable inlet guide vane was analysed. Also, differences in operating characteristics and performance caused by changes in the methane content of biogas and ambient temperature were examined.

• Korean Journal of Computational Design and Engineering
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• v.1 no.1
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• pp.20-32
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• 1996

The boundary evaluation technique for Boolean operation on non-manifold models which is regarded as the most popular and powerful method to create and modify 3-D CAD models has been developed. This technique adopted the concept of Merge and Selection in which the CSG tree for Boolean operation can be edited quickly and easily. In this method, the merged set which contains complete information about primitive models involved is created by merging primitives one by one, then the alive entities are selected following the given CSG tree. This technique can support the hybrid representation of B-rep(Boundary Representation) and CSG(Constructive Solid Geometry) tree in a unified non-manifold model data structure, and expected to be used as a basic method for many modeling problems such as data representation of form features, and the interference between them, and data representation of conceptual models in design process, etc.

• IE interfaces
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• v.21 no.1
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• pp.75-84
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• 2008

It is a difficult task for decision makers(DMs) to choose an appropriate release plan which balances the conflicts between water storage and hydro-electric energy generation in a multi-reservoir operation problem. In this study, we proposed a DEA-based ranking procedure by which the DM can rank the potential alternatives and select the best solution among the Pareto-optimal solutions. The proposed procedure can resolve the problem of mix inefficiency that may cause errors in measuring the efficiency of alternatives. We applied the proposed procedure to the multi-reservoir operation problem for the Geum-River basin and could choose the best efficient solution from the Pareto-set which were generated by the Coordinated Multi-Reservoir Operating Model.

• Korean Journal of Hydrosciences
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• v.4
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• pp.65-79
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• 1993

Selection of the best operating rule among a set of alternatives for a multipurpose reservoir system operation requires to evaluate many minor criteria in addition to the major objectives assessed to the system. These problems are sufficiently complex and difficult that they are beyond heuristic decision rules and experiences in case several noncommensurable multiple criteria are included in the evaluation. With the assistance of multicriterion decision analysis techniques, it is possible to select the best one among various alternatives by systematically comparing and ranking the alternatives with respect to the criteria of choice. Evaluation criteria for multipurpose reservoir system operating rules were identified and defined, and the multicriterion decision analysis techniques were applied to evaluate the four existing operating rules of the Chungju multipurpose project according to the identified nine multiple criteria. The application results show that the methodology is very efficient to select the best operation alternative among a finite number of operating rules with many evaluation criteria for a large-scale reservoir system operation.

• IE interfaces
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• v.16 no.4
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• pp.496-506
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• 2003

This study examines the background and necessity of the product certification (KS) and the system authentication (ISO 9000), and their characteristic so as to compare and analyze the possibility of interaction of product certification and system authentication. It tries to suggest an efficient operation system as an integrated management system and analyzes the certification case of K, a manufacturer of kitchen utensils. We believe that the study will help companies minimize their expenses and efforts to establish, operate, and maintain the corporate standard system. In addition, to effectively achieve our goal, we have also made a study of both literature and case and suggested technical guidance to get integrated management system certification. By these methods, we analyzed the effects and problems that come with the introduction and application of the integrated system of product certification and system authentication in order to set up a system to fit to the mechanism of Korean companies. Moreover, we have suggested the model of integrated operation and the benefits that come after acquiring certification.

• Journal of the Korean Operations Research and Management Science Society
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• v.26 no.1
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• pp.71-85
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• 2001

This paper considers a cost model for a U-shaped manufacturing cell formation which incorporates a required number of machines and various material flows together under multi-part multi-cell environment. The model is required to satisfy both the specified operation sequence of each part and the total part demand volume, which are considered to derive material handling cost in U-shaped flow line cells. In the model several cost-incurring factors including set-up for batch change-over, processing time for operations of each part, and machine failures are also considered in association with processing load and capacity of each cell. Moreover, a heuristic for a good machine layout in each cell is newly proposed based on the material handling cost of each alternative sequence layout. These all are put together to present an efficient heuristic for the U-shaped independent-cell formation problem, numerical problems are solved to illustrate the algorithm.