• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.19 no.6
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• pp.476-484
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• 2007

Recently, in accordance with the buildings are becoming to large-sizes, high-stories, the large scaled facilities and equipments in machine room are quite demanding, and the generated noise volume according to this situation is on increasing. Since such noise is becoming to the object of a serious civil appeal, it is the real situation that a reduction countermeasure against the machine room equipment noise is keenly necessitated. On such viewpoint, this study has recorded, measured the noises which were generated from each individual as same as the whole equipped machines and tools, on the object of the dormitory machine rooms of the 3 colleges that haying mutually different peculiarities, then after grasp-ing their characters and acoustic powers, this research has verified its prediction possibility and the authenticity by comparison the estimated numerical value with the actually measured numerical value through the acoustic simulation. After grasping the prediction possibility in such way, by utilization of the sound absorption material in the machinery room, from the stage of design, the soundproof measures for the noise reduction at machine room could be regulated effectively, and it is also considered that such data would be utilized as the fundamental material for an establishment of the measure for sound insulation.

• Knowledge Management Research
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• v.10 no.4
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• pp.163-183
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• 2009

Numerous studies in the field of buyer-supplier relationship research have focused on the buyer's performance. In contrast, supplier's performance has been paid relatively little attention by researchers, especially the research about the supplier's innovation in the relationship is still in its early stage. In this paper, we examine the relation between the attribute of buyer-supplier relationship and the attribute of supplier's innovation through case research. We define the attribute of buyer-supplier relationship as 'tie strength' (Granovetter, 1973), and the attribute of supplier's innovation as 'exploitation or exploration' (March, 1991). We selected the semiconductor equipment industry of U.S.A, Japan and Korea and firm (JUSUNG Engineering) as cases that examine the relation. We found that a strong tie relationship is positively associated with supplier's exploitation based innovation, and a weak tie relationship is positively related to it's exploration based innovation in this research also. In addition, we could verify reduction of strong tie relationship cause supplier's organizational change.

• Interaction and multiscale mechanics
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• v.1 no.3
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• pp.369-379
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• 2008

A combined stochastic diffusion and mean-field model is developed for a systematic study of the grain growth in a pure single-phase polycrystalline material. A corresponding Fokker-Planck continuity equation is formulated, and the interplay/competition of stochastic and curvature-driven mechanisms is investigated. Finite difference results show that the stochastic diffusion coefficient has a strong effect on the growth of small grains in the early stage in both two-dimensional columnar and three-dimensional grain systems, and the corresponding growth exponents are ~0.33 and ~0.25, respectively. With the increase in grain size, the deterministic curvature-driven mechanism becomes dominant and the growth exponent is close to 0.5. The transition ranges between these two mechanisms are about 2-26 and 2-15 nm with boundary energy of 0.01-1 J $m^{-2}$ in two- and three-dimensional systems, respectively. The grain size distribution of a three-dimensional system changes dramatically with increasing time, while it changes a little in a two-dimensional system. The grain size distribution from the combined model is consistent with experimental data available.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.1205-1211
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• 2017

The Propulsion System Test Complex(PSTC) was constructed for the verification test of each stage's propulsion system of KSLV-II. Main Control System(MCS) is the system to operate the onboard equipment and the ground equipment of the PSTC simultaneously. This paper describes the critical design, the development status, and test results of Main Control System. The MCS will be used for the interface connection between ground control systems and onboard equipment. Test sequence and operation process of the Work Manager will be conducted by MCS.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.5
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• pp.50-59
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• 2003

It was known that high pressure injection is an effective method to enhance thermal efficiency and decrease exhaust emissions in diesel engines. If injection pressure becomes ultra high, it is predicted that there may be a suitable injection pressure which the enhancement rate of spray characteristics is moderate. Also, there may be a limit injection pressure which spray characteristics is reversed and get worse. But these are unknown. To investigate a suitable injection pressure and a limit injection pressure, ultra high pressure injection equipment(UHPIE), which can realize the injection pressure of 3,200bar, was developed. UHPIE is a basic apparatus of single shot injection, and ultra high pressure was achieved by second stage rapid compression in short time. From the evaluation of UHPIE, a injection curve like a conventional diesel engine(jerk type) was realized. Also, it was proved that repetition of experiment was excellent. Therefore it was found that there was no problem to perform the study on the ultra high pressure injection with UHPIE. Consequently, the foundation of the study on ultra high pressure injection could be established.

• Journal of Electrical Engineering and Technology
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• v.9 no.2
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• pp.635-642
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• 2014

The space charge behaviors of oil-paper insulation affect the stability and security of oil-filled converter transformers of traditional and new energies. This paper presents the results of the electrical aging of oil-impregnated paper under AC-DC combined voltages by the pulsed electro-acoustic technique. Data mining and feature extractions were performed on the influence of electrical aging on charge dynamics based on the experiment results in the first stage. Characteristic parameters such as total charge injection and apparent charge mobility were calculated. The influences of electrical aging on the trap energy distribution of an oil-paper insulation system were analyzed and discussed. Longer electrical aging time would increase the depth and energy density of charge trap, which decelerates the apparent charge mobility and increases the probability of hot electron formation. This mechanism would accelerate damage to the cellulose and the formation of discharge channels, enhance the acceleration of the electric field distortion, and shorten insulation lifetime under AC-DC combined voltages.

• Journal of the Korean Society of Systems Engineering
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• v.14 no.2
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• pp.33-40
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• 2018

This paper is based on the interim result of ongoing research and development project to develop a software system which support procurement activities, namely PeMSS (Procurement Engineering Management Support System). PeMSS is a system that enables development requirements for each equipment and help designing equipment meeting the purchase requirements. Procurement at EPC (Engineering Procurement and Construction) and operational stage of a plant is an important area that determines the integrity and profitability of the plant. Procurement of unsuitable equipment due to selection of suppliers that do not meet or omit critical requirements in purchase specification can result in enormous cost increase due to such as delay in EPC project, unsatisfactory performance and reduced plant operation time. In spite of the importance of the procurement engineering, there is a lack of support system for systematic preparation of purchase specification, so development of the procurement specification is basically relying on the experience of the engineers in charge. Accordingly, it is needed to develop the PeMSS to help procurement engineers develop procurement specification based on systems engineering approach. This paper introduces the design of the PeMSS.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.05a
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• pp.237-238
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• 2023

When primer is applied manually, adhesion performance decreases due to a decrease in primer penetration performance on the surface, and construction period delay may occur due to a long time due to a decrease in work efficiency when a large area is worked using a conventional roller. In addition, in the case of the roller method, precision work in corners and narrow spaces is not possible, so it is urgent to come up with measures to ensure uniform quality. In addition, secondary work occurs to remove fine powder from the surface before primer application, resulting in construction period delay due to the rise of the working stage. Therefore, in this study, equipment was used instead of manual work for primer work, and as a result, penetration performance and adhesion performance were improved about twice. From these results, it was confirmed that favorable results such as improving work speed, securing high quality, improving the working environment, and resolving the shortage of functional workers can be obtained.

• ETRI Journal
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• v.10 no.3
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• pp.157-164
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• 1988

In proportion to the increased density in electronic packaging from chip to system levels of telecommunication system, thermal management is becoming a vital subject to save the cost of the electronic product and to maintain high reliability. The key to the successful application of the thermal management technique is the capability to predict the equipment thermal behaviors in early stage of system development and product design. This paper describes the application of correlations of natural convection to TDX-10 digital switching system, which has been under the 5 year development project since 1987, in order to predict equipment temperature and thermal behaviors whihin a rack.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.25 no.1
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• pp.58-64
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• 2015

There are a lot of different types of noise from construction site and it depends on construction stage, equipment type and number of operating equipments. The problem is that the almost noise from construction site is high level and some kinds of noise levels are over 100 dB. In addition, if construction site is located in downtown, there are a few options to reduce noise level. Therefore several site mitigation plans were developed to reduce different types of construction noises such as breaker work, gang form and asphalt saw. They were applied in site and evaluated noise reduction performance. The test result of site insertion loss was between 4~8 dB depends on the equipment and type of work.