• Journal of The Korean Astronomical Society
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• v.29 no.spc1
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• pp.143-144
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• 1996

Two-component models (normal star and degenerate star components) are the simplest realization of clusters with a mass spectrum because the high mass stars quickly evolve off leaving degenerate stars behind, while low mass stars survive for a long time as main-sequence stars. In the present study we examine the post-collapse evolution of globular clusters using two-component Fokker-Planck models that include three-body binary heating. We confirm that a simple parameter ${\epsilon}{\equiv} (E_{tot}/t_{rh})/(E_c/t_{rc})$ well describes the occurrence of gravothermal oscillations of two-component clusters. Also, we find that the degree of instability depends on the steepness of the mass function such that clusters with a steeper mass function are less exposed to instability.

• 한국전산유체공학회:학술대회논문집
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• 2004.10a
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• pp.43-46
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• 2004

Numerical analysis for pressure drag on boattail afterbodies have been studied by Mach number, boattail angle and length ratio of body diameter and base diameter using CFD-FASTRAN that the commercial external flow CFD code. The numerical results have been compared with the experimental data that have been shown pressure drag reduction and supersonic turbulent flow characteristics for boattail afterbodies. And the prediction equation tot boattail base drag has been made by the numerical results about Mach number and boattail configuration parameters.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1992.10a
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• pp.204-208
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• 1992

The purpose of this research is to construct the experimental test set-ups and establish a series of performance test program for the domestically developed fluid couplings, and to provide a software to store and utilize these experimental data which can be used to improve the performance of the fluid coupling and solve on the job problems confronted in operation. The performance test consists of taking measurement of torque rpm and efficiency of the fluid coupling for three different amount of working fluid inside with various loads to the output shaft and finally investigating the torque rpm and efficiency characteristics of the fluid coupling with respect to these parameters. The results of this study can contribute valuable references tot the development of variable speed fluid coupling and torque converter currently pursued by the domestic industry.

• Proceedings of the IEEK Conference
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• 2003.07a
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• pp.262-265
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• 2003

Radiofrequency thermal ablation (RTA) as one of the microwave hyperthermia is becoming the treatment of choice for small but inoperable tumors of the liver. In this paper, we designed the applicator composed of semi-rigid coaxial cable antenna with a ring slot for RTA. To optimize the maximum output of radiation at 2450 MHz, we simulated the antenna using Electromagnetic simulation tools Maxwell program and analyzed the return loss and the electric field $E_{tot}$ at the near-field region between the simulation results and measurement results. As a result, we obtained the return loss of -29.786 dB at 2450 MHz when the antenna was placed between two blocks of a pig's liver, and the measurement results agreed with the simulation results well. Therefore, this semi-rigid coaxial cable antenna with a ring slot can be used very usefully as the applicator for RTA.r RTA.A.

• Proceedings of the IEEK Conference
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• 2003.11b
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• pp.191-194
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• 2003

In this paper, we describe the effective way of keyboard-hacking prevention and authentication system using a Smart Card. These days the securing information matters for pc-users are becoming more important as the internet business grows rapidly, and the ubiquitous computing environment is open tot everyone. Therefore, PC authentication is necessary to handle the access control to the target PC. Also, the keyboard-inputting information is necessary to be protected properly against the malicious attack. In this paper, we propose the keyboard-hacking protect systems and authentication system using a Smart Card, and show the conveniency and efficiency in the results.

• Journal of Family Resource Management and Policy Review
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• v.8 no.3
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• pp.33-46
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• 2004

This study examined the effects of consumers' perceptions and expectations about refund on consumers' behavior to refund and its outcome. Major results of this study could be summarized as follows. First, consumers' perceptions and expectations about refund were higher in the case of defective products. However, consumers' behavior to refund were generally passive resulting in the low chance of refund. When there was no defects in product, consumers perceptions and expectations for refund were generally lower resulting in passive and the low chance of refund. Second, when there was defects in product, both consumers' perceptions and expectation tot refund influenced their active behaviors for refund, but not in the successful outcome. In contrast, when there was no defect, those two variables impacted on the behaviors for refund positively In addition, the more active those behaviors requesting for refunds were, the more successful outcome in refund request.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.6
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• pp.1416-1424
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• 1996

The problem of optimaizing multiframe targe detection (MFTD) performance si discussed. The MFTD problem is treated as a multiple hypothesis desision problem, and a ne optimality criterion for the MFTD problem is established. It is of Neyman-Pearson (NP) type which is extended to multiple hypothesis cases. An optimal solution with respect tot eh established criterion is derived, and also proposed is a suboptimal solution which reduces the compelexity accompanying the optimal one. The trade-off between the reduction of complexity and the amount of loss in the detection performance is also studied. The proposed algorithm is applied to an active sonar system and the performance is evaluated via Monte-Carlo simulations.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.12S
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• pp.1292-1298
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• 2003

In this paper, dc reactor lot the inductive high-Tc superconducting fault current limiter (SFCL) was optimally designed by finite element method(FEM). The Prototype high-Tc do reactor was manufactured and compared to the results of design. This dc reactor consists of 4∼stacked double pancake coils which are wounded with Bi-2223 wire coated with SUS315L. Kapton tape is used for the insulation of turn to turn and layer to layer. Each pancake is connected in series by soldering Finally, optimal design and manufacture method lot the dc reactor is suggested in this paper. Through the comparison of result of optimal design and experimental result of prototype high-Tc superconducting dc reactor, reliance on the design of the high-Tc dc reactor tot the 1.2 kV/80 A SFCL is proved.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.28A no.9
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• pp.752-760
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• 1991

The computer aided analysis is performed to investigate the influence of physical parameters (thickness and doping concentration, etc.) in the window, emitter, base on the efficiency characteristics of a uniformly doped hetroface cell. A field aided heteroface cell is newly designed on a basis of optimum data obtained from the theoretical analysis. The field aided heteroface cell fabricated using MOCVD exhibits a total/active area conversion efficiency of EFF. (tot) = 18.9% /EFF. (act.) = 21.4% under the natural incident light of 56.2 mW/cm\ulcorner having a low series resistance of Rs = 0.94 \ulcornercm\ulcornerand a high spectral response of S.R. (ext) > 90% in a range of $7700{\AA}$ < $8500{\AA}$.

• Bulletin of the Korean Chemical Society
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• v.35 no.2
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• pp.513-517
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• 2014

Two donor-acceptor-donor monomers such as 3,5-bis(4-bromophenyl)-1,2,4-oxadiazole (BOB) and 3,5-bis(5-bromothiophen-2-yl)-1,2,4-oxadiazole (TOT) incorporating electron transporting and hole blocking 1,2,4-oxadiazloe moiety were copolymerized with light emitting fluorene derivative via Suzuki polycondensation to afford two new polymers, PFBOB and PFTOT, respectively. The optical studies for polymers PFBOB and PFTOT revealed that the band gaps are 3.10 eV and 2.72 eV, respectively, and polymer PFBOB exhibited a deep-blue emission while polymer PFTOT showed blue emission in chloroform and as thin film. The photoluminescence quantum efficiencies (${\Phi}_f$) of polymers PFBOB and PFTOT in chloroform calculated against highly blue emitting 9,10-diphenylanthracene (DPA, ${\Phi}_f=0.90$) were 1.00 and 0.44, respectively.