• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.1170-1175
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• 2003

Recently, the disturbance caused by an optical disk vibration and the external vibration/shock are more serious problem in an optical disk drives (ODD) as an ODD become small size and rotation speed increases. The conventional controller cannot cope with the mentioned problems properly when the disturbance and vibration are larger than some range. Therefore, we propose a new control scheme using a disturbance observer (DOB) and it can control the aforementioned problems. The designed the controller is applied to a commercial ODD in focusing direction, then its validity is proved by experimental method. By rising the disturbance observer theory, the focusing performance is conspicuously improved in the presence of sinusoidal vibrations or a shock disturbance. This algorithm also applies to a tracking structure also, because focusing structure is very similar to it.

• Korean Business Review
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• v.6
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• pp.153-179
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• 1993

The main purpose of this study is to suggest the new strategic management model for the future successful company. The new model consists of the following structure. First, to identify the object dimension. The upper object is to satisfy the customers needs. And the lower object is to satisfy the workers needs. Second, to identify the external enviromental problems dimensions. There are five dimensions. They are ethical responsinilities, government-business alliances, collaboration amongst competitors, innovative invester-company relations, and globalization of enterprise. Third, to identify the internal enviromental problems dimensions. There are two dimensions. They are new organizational forms and integrated subcultures. Fourth, to find the solution for the above dimensions. The solution is as follow. All the managers and workers must have business reengineering minds and apply the complexity management. And the company should construct the strategic information systems.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.559-560
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• 2006

The paper presents solutions of conventional piezoresistive pressure sensors. Deflection of diaphragm by external stress causes some problems, because the electrode is deposited on the diaphragm formed piezoresistors. To solve these problems, piezoresistors is formed by two implantation steps. To fabricate diaphragm, the backside silicon etching step is done by immersing the wafer into TMAH solution. $30{\mu}m$ thick diaphragm is obtained. Sensitivity of the piezoresistive pressure sensor fabricated is 48.6 mV/V-psi.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2019.05a
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• pp.83-84
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• 2019

Free-form buildings refer to geometric external structures in curved form, unlike conventional structures with straight lines. The development of construction technologies for the implementation of these Free-form buildings is ongoing. However, there are still many restrictions on the construction technology of Free-form buildings, resulting in problems such as increased construction period and increased construction costs. Therefore, it is urgent to develop building technology for the construction of Free-form building in order to secure competitiveness in the global Free-form building market. Accordingly, this study proposes Two-sided multi-point press technology that can solve problems of existing technology and implement FCP(Free-form Concrete Panel).

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2039-2042
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• 2008

Recently, Electronic & Electrical Products have problems how to reduce heat in trend reducing size and increasing speed. heat pipes worked by latent heats can solve problems for effective and quiet electronic applications. Heat Pipes have to be suitably designed for the external conditions due to showing optimum performance. it has influence on efficiency of heat pipes to the exterior structure changed by length, bending angle, diameter. Designing heat pipes has depended on experience from trial and error. this method wasted too many resources, but can't guarantee efficiency. to prevent those wastes, this study aims at making the thermal transfer coefficient predicting efficiency. In this study, the thermal transfer coefficient has been made from experimental results that used variables - lengths between heat source and radiation, bending angles, diameters of heat pipes. variables become non-dimensional in modeling process for making the coefficient.

• Journal of Powder Materials
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• v.27 no.4
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• pp.318-324
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• 2020

In the present work, an explicit finite element analysis technique is introduced to analyze the thermal stress fields present in the additive manufacturing process. To this purpose, a finite element matrix formulation is derived from the equations of motion and continuity. The developed code, NET3D, is then applied to various sample problems including thermal stress development. The application of heat to an inclusion from an external source establishes an initial temperature from which heat flows to the surrounding body in the sample problems. The development of thermal stress due to the mismatch between the thermal strains is analyzed. As mass scaling can be used to shorten the computation time of explicit analysis, a mass scaling of 108 is employed here, which yields almost identical results to the quasi-static results.

• Journal of Korea Society of Digital Industry and Information Management
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• v.18 no.4
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• pp.41-46
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• 2022

In the fourth industrial era, when various technologies are fused and combined, new and advanced technologies from other industries are used extensively in the maritime industry field. New security threats are also increasing along with the development of new technologies. In addition, in incorporating convergence technologies into the maritime industry, various problems, such as communication definitions and procedures between technologies and customer-customized delays, occur. In this paper, for the problems mentioned above, research results on the network configuration of safer autonomous vessels by supplementing and fusing existing solutions rather than developing new technologies are proposed. In conclusion, the entire network consists of VDI and presents additional configurations to ensure confidentiality, integrity, and availability, which are the three security elements. According to the composition of such a convergence network, it is intended to help prepare countermeasures to protect internal data from external threats.

• Journal of the Korean Society for Library and Information Science
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• v.7
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• pp.197-223
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• 1980

This paper consists of two parts: the first part discusses general problems of microforms as transmission and storage media of research information, especially in view of user's reactions to this unconventional media. Many articles and surveys from major American library journals and other professional publications have been mentioned and reviewed to find out the common issues which could be relevent to Korean case. The latter part is the analysis of the two sets of surveys. One was done from 5 research libraries in Seoul and the other, from 150 researchers who were the users of the libraries. The major findings are: The research libraries in Korea are in the infant stage of building their microform research collection. They are doing their special effort to level up the weaknesss of the collection. Presently, general level of usage is very low, although the users showed a positive attitude toward this unaccustomed media. They are well convinced with necessity of use of microforms in their research and they have correct ideas about some of the problems they are going to face along with the eventual heavier use of the materials. They are psychologically ready to accept them and to make a good use out of them if some of the external conditions for proper use of the material would be guaranteed.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.2
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• pp.70-75
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• 2014

A track circuit is a critical piece of equipment that allows the existence of the trains on the track to be detected. Train detection is very important for the signal safety equipment. It allows for the confirmation of a train's location, the locking of switch points, the coordination of safe distance between trains, and the advance notice of a train's arrival. Track circuits can be powered by AC or DC. The DC track circuits are usually used on non-electrified tracks. On these tracks, many signal errors can be caused by lightning or problems with the power source. These problems can also cause damages to the rectifiers which must be repaired or replaced, promptly. This issue is especially problematic in the summer because of the higher frequency of thunderstorms. Issues with track circuits also cause problems for other equipment, such as railroad crossings and switch points. This further disrupts the safe operation of trains. This study aims to enhance maintenance efficiency and improve safety by utilizing parallel operation and multiplexing of a DC track circuit as well as installing an external surge protector. The experimental results on the operation of the proposed method is also presented.

• Journal of Korean Library and Information Science Society
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• v.37 no.2
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• pp.73-95
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• 2006

The objective of this study is to analyse the current status and problems of the junior college libraries in Korea which is being placed in the inferior environment relatively and to present the improvement program against hereupon. The concept and an objective of the junior colleges were examined, the problems against an external environment through various statistics of their academic libraries were also presented. The instance academic libraries based on their number of book collection in the city of Taegu area were selected to prepare the improvement program. Information service instance which hits to the junior colleges were collected through analysing the web site of the corresponding library, and the depth interview to the corresponding junior college librarians was also executed.