• Journal of the Korean Society for Precision Engineering
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• v.23 no.3 s.180
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• pp.171-178
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• 2006

The sonication mettled is widely used with surfactants to suspend individual single-walled carbon nanotubes in solution, and it is well known that sonication-induced tube cutting occurs. Recently, it is found out that ultrasonicated nanotubes yield simultaneous separation by tube length and diameter. Nanotubes that have been cut shortest possess the greatest enrichments of large-diameter species. In this study, single-walled carbon nanotubes are cut using a ball milling method. Similar fracture behavior is observed fur the ball milled nanotubes: i.e., large diameter tubes are cut shorter. The ability to separate carbon nanotubes by diameter and length will contribute to tile development of nanotube-based applications.

• Proceedings of the KWS Conference
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• 1998.10a
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• pp.129-132
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• 1998

The dynamic resistance monitoring in primary circuit or T/C is one of the important issues in that in-process and real time quality assurance of resistance spot weld is needed to increase the product reliability. It is well known that tile dynamic resistance curve gives us very useful information about nugget growth and weldability. In the present paper, a new dynamic resistance detecting method is presented as a practical manner of weld quality assurance using instantaneous current and voltage measured by primary circuit. Primary dynamic resistance patterns are basically similar to those of the secondary, but there is evident advantage such as no extra devices are needed to obtain the quality assurance index and eventually feedback control will be possible caused by T/C based monitoring system.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.11a
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• pp.357-362
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• 1996

LOFT LBLOCA test, LP-02-6 was analyzed using RELAP5/MOD3.2. It has a distinguished thermal-hydraulic phenomenon of a positive bottom-up core flow in tile blowdown phase. A modified nodalization which is based on that used in LP-LB-1 calculation by Lubbesmeyer was used in the calculation. RELAP5/MOD3.2 predicted overall system hydraulic behavior relatively well. However, the bottom-up quenching in the middle part of the core was not predicted sufficiently. It was demonstrated also that the peak cladding temperature can be predicted well by adjusting a discharge coefficient. But more improvements are needed in order to apply this code to actual plants with less user dependency.

• Journal of KSNVE
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• v.8 no.6
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• pp.1037-1042
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• 1998

This paper discusses the dependence of the convergence rate on the acoustic error path in these popular algorithms and introduces new algorithms which increase the convergence region regardless of the time-delay in the acoustic error path. We also Propose a novel control algorithm (AFC/CAFC) for tonal noise cancellation. The proposed algorithm estimates the magnitude and phase of the tonal noise. The algorithm uses the steepest descent method for the phase/magnitude estimation. Performances of tile CAFC algorithm are presented in comparison with those by the AFC algorithm based on computer simulations and experiments.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2000.10a
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• pp.17-20
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• 2000

Change in business has ushered in new corporate value for the success of the future. Excellent companies understand this and seek to realise the new value to procure their status in the market. The new corporate value is composed of those of employees', customers' and shareholders', and of these three, the first is the footing for improving tile others. Korea Telecom has measured employees' value every you since 1998 with an eye to achieving corporate vision, Cyberworld Leader. In this paper, we analyse the case of two leading telcos to enhance employees' value. After that, we explicate the goals, concepts and future directions of the analysis of employees' value in Korea Telecom.

• Proceedings of the Safety Management and Science Conference
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• 2001.05a
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• pp.39-43
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• 2001

The existent system of management for Measurement of Safety Cost are not effective because of the data loss and time loss and occurrence of errors through manual calculation. Therefore, tile development of the software for measurement of safety cost can solve the problem through the systematic calculation for safety cost and converting the related data to database, and also can build the strategy of the investment of Safety cost through analysing and comparing with the past data in the database. As a part of development of the software of Measurement of Safety Cost which is appropriate for the domestic environment, this study is developing a software based on Noguji method, which is one of the methods of Measurement of Safety Cost, and to appraise the efficiency of the management of Measurement of Safety Cost we will implement and improve the software in the case of the domestic enterprises.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.4 s.121
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• pp.363-369
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• 2007

The purpose of the study is to obtain acoustical information to prevent eavesdropping of the glass window. Speech intelligibility was investigated on the vibration sound detected from the glass window of a conference room. Objective test using speech transmission index(STI) was performed to estimate quantitatively the speech intelligibility. STI was determined based on tile modulation transfer function(MTF) of the room-glass window system. Using Maximum Length Sequency(MLS) signal as a sound source, impulse responses of the glass window and MTF were determined by signals from accelerometers and laser doppler vibrometer. Finally, speech intelligibility of the interior sound and window vibration were compared under different sound pressure levels and amplifier gains to confirm the effect of measurement condition on the speech intelligibility.

• Journal of the Korean Professional Engineers Association
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• v.16 no.1
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• pp.13-19
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• 1983

As one of staff members participated in the full course of the plant construction project of On-san Refinery to its successful completion. I had my past expierence that the plant construction project was so complicated, and a Long period required, and thus there were so money problems to be solved. Among the problem, I mainly noticed that the following listed points were solved and improved. 1. Each drawing should be in every accuracy possible. 2. Contract should be specified in every detail possible. 3. All invoiced prices of breack down list should be coped with the current market prices. 4. All execution of work should be in the most accuracy. A. Planing execution of work. B. Coordination with supervisor group. C. Economical method for execution of work. D. Safety control. 3, Calculation work field should be established seperately 6. Each staff members should be work at the best of his pride.

• Journal for History of Mathematics
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• v.16 no.3
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• pp.101-108
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• 2003

The RSA cryptosystem is most commonly used for providing privacy and ensuring authenticity of digital data. 1'his system is based on the difficulty of integer factoring. Many attacks had been done, but none of them devastating. They mostly illustrate the dangers of improper use of RSA. Improper use implies many aspects, but here we imply the misuse of the parameters of RSA. Specially, sizes of parameters give strong effects on the efficiency and the security of the system. Parameters are also related each other. We analyze the relation of them. Recently many researchers are interested in side-channel attacks. We also investigate partial key exposure attacks, which was motivated by side-channel attacks. If a fraction of tile secret key bits is revealed, the private key will be reconstructed. We also study mathematical background of these attacks, solving modular multivariate polynomial equations.

• Proceedings of the Korean DIstribution Association Conference
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• 2003.05a
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• pp.55-70
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• 2003

The most transport companies are placing increasing emphasis on powerful new techniques for planning their vehicle operations. They have tried to improve their vehicle control and customer service capability by adopting tile advanced information technology, such as GPS(Global Position System) and Using Digital Map. But researches on the VRSP(vehicle routing St schedule problem) in this situation were very few. The purpose of this research is to develop vehicle scheduling heuristics for making a real-time dynamic VRSP under the situation that GPS and using Digital Map are equipped to the transport company. Modified savings techniques are suggested for the heuristic method and an insertion technique is suggested for the dynamic VRSP. The urgent vehicle schedule is based on the regular vehicle schedule. This study suggest on VRSP system using GPS and Digital Map and the performance of the suggested heuristics is illustrated through an real case example.