• ETRI Journal
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• v.7 no.4
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• pp.15-23
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• 1985

Korea is trying to build the advanced telecommunications system to lead the information society in advance, which will demand a large amount of internal funds. The degree of rate level of telecommunications services. The objective of this article is to set up the principle which will be applied to decide the level of total revenue requirement(TRR) of telecommunications services in Korea. The trait of the principle is to specify the relation between the investment volume in telecommunications and gross fixed capital formation (G. F. C. F)at the national level. This article also proposes the m,d-term alternatives of strategic variables for the application of the principle.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.16-17
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• 2005

Local lifetime control by ion implantation has become an useful tool for production of modern power devices. In this work, punch-through diodes were irradiated with protons for the high speed power diode fabrication. Proton irradiation was executed at the various energy and dose conditions. Characterization of the device was performed by I-V, C-V and Trr measurement. We obtained enhanced reverse recovery time characteristics which was about 45% of original device and about 73% of electron irradiated device. The measurement results showed that proton irradiation was able to effectively reduce minority carrier lifetime.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.320-323
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• 2002

This paper discusses process design of cold forging for inner tooth part, drum clutch. In respect to high productivity, low material consumption and low piece production costs, Metal forming has more merits than machining process. Net shape forming is huh technology which satisfies merits of metal forming and achieves high accuracy. Recently, net shape forming method widely applied because of high productivity, low material consumption and low piece production costs using press. In this study, the method which accuracy of drum clutch, automatic transmission pin, can be improved is discussed. First, process variables for process design of drum clutch are selected, and then process design is accomplished using forming analysis method. from forming analysis, forming load, stress, unfiling part is obtained. and comparing these results, optimal process design can be determined.

• Nuclear Engineering and Technology
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• v.49 no.1
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• pp.189-195
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• 2017

Gel dosimeters have unique advantages in comparison with other dosimeters. Until now, these gels have been used in different radiotherapy techniques as a reliable dosimetric tool. Because dose distribution measurement is an important factor for appropriate treatment planning in different radiotherapy techniques, in this study, we evaluated the ability of the N-isopropylacrylamide (NIPAM) polymer gel to record the dose distribution resulting from the mixed neutron-gamma field of boron neutron capture therapy (BNCT). In this regard, a head phantom containing NIPAM gel was irradiated using the Tehran Research Reactor BNCT beam line, and then by a magnetic resonance scanner. Eventually, the $R_2$ maps were obtained in different slices of the phantom by analyzing T2-weighted images. The results show that NIPAM gel has a suitable potential for recording three-dimensional dose distribution in mixed neutron-gamma field dosimetry.

• Proceedings of the KIPE Conference
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• 2016.11a
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• pp.147-148
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• 2016

토템폴 구조는 브리지리스 부스트 역률보상회로 중에서도 저손실, 고효율, 저비용 그리고 낮은 전도 EMI의 특징으로 인해 많이 사용된다. 토템폴 구조의 역률보상 회로는 내부 다이오드의 역회복 문제로 인해 Si MOSFET을 이용한 전류연속모드 구동할 수 없어 전류 불연속 모드 혹은 임계 도통 모드로 동작시키는 것이 통상적이다. 본 논문에서는 역회복 문제를 해결해 전류연속모드 구동하기 위해 기존 Si MOSFET보다 낮은 역회복 전하(Qrr)와 역회복 시간(Trr)를 가지는 SiC MOSFET을 이용하여 토템폴 역률 보상 회로를 구현하고 이를 시뮬레이션과 실험을 통해 검증했다.

• Journal of Korean Society for Quality Management
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• v.42 no.3
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• pp.279-290
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• 2014

Purpose: The purpose of this study is to propose adoption of QFD and Stage-gate in order to analyze the quality of korea defense system. Methods: Drawing change data of initial production phase in korea defense system were anlayzed and a practical method was proposed. Results: The results of this study are as follows; Off line Quality Control should be introduced in development phase. Specially, in case of defense system, the best method is QFD(Quality Function Deployment) and Stage-gate process. At first, QFD 1 step defines product planning from VOC(Voice Of Customer), QFD 2 step specifies part planning from product planning, QFD 3 step defines process planning from part planning, QFD 4 step defines production planning from previous process planning. Secondly, Stage-gate process is adopted. This study is proposed 5 stage-gate in case of korea defense development. Gate 1 is located after SFR(System Function Review), Gate 2 is located after PDR(Preliminary Design Review), Gate 3 is located after CDR(Critical Design Review), Gate 4 is located after TRR(Test Readiness Review) and Gate 5 is located before specification documentation submission. Conclusion: Off line QC(Quality Control) in development phase is necessary prior to on line QC(Quality Control) in p roduction phase. For the purpose of off line quality control, QFD(Quality Function Deployment) and Stage-gate process can be adopted.

• Nuclear Engineering and Technology
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• v.49 no.5
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• pp.953-967
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• 2017

In this paper, a complete station blackout (SBO) or complete loss of electrical power supplies is simulated and analyzed in a downward cooling 5-MW pool-type Material Testing Reactor (MTR). The scenario is traced in the absence of active cooling systems and operators. The code nodalization is successfully benchmarked against experimental data of the reactor's operating parameters. The passive heat removal system includes downward water cooling after pump breakdown by the force of gravity (where the coolant streams down to the unfilled portion of the holdup tank), safety flapper opening, flow reversal from a downward to an upward cooling direction, and then the upward free convection heat removal throughout the flapper safety valve, lower plenum, and fuel assemblies. Both short-term and long-term natural core cooling conditions are simulated and investigated using the RELAP5 code. Short-term analyses focus on the safety flapper valve operation and flow reversal mode. Long-term analyses include simulation of both complete SBO and long-term operation of the free convection mode. Results are promising for pool-type MTRs because this allows operators to investigate RELAP code abilities for MTR thermal-hydraulic simulations without any oscillation; moreover, the Tehran Research Reactor is conservatively safe against the complete SBO and long-term free convection operation.

• Journal of the Korea Institute of Military Science and Technology
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• v.25 no.4
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• pp.329-338
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• 2022

This paper provides a case study of development testing and evaluation of design goal of Interferometric SAS (Synthetic Aperture Sonar) system that is developing supported by Civil-Military Technology Cooperation Center in offshore fields. For Deep water operating capabilities evaluation, We have surveyed candidate field, bathymetric mapping and target identification over 200 m depth, East Sea. In testing phase, We have provided environmental information of testing field include water column, seabed and weather condition in real time. And to compare excellency of developing InSAS, we have gather commercial imaging sonar system data with same target. This case study will support the Test Readiness Review of future underwater surveillance system developing via investigate marine testing field environment, testing facilities and planning.

• The Transactions of the Korea Information Processing Society
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• v.2 no.6
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• pp.903-917
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• 1995

In most database systems images have been indexed indirectly using related texts such as captions, annotations and image attributes. But there has been an increasing requirement for the image database system supporting the storage and retrieval of images directly by content using the information contained in the images. There has been a few indexing methods based on contents. Among them, Pertains proposed an image indexing method considering spatial relationships and properties of objects forming the images. This is the expansion of the other studies based on '2-D string. But this method needs too much storage space and lacks flexibility. In this paper, we propose a more flexible index structure based on kd-tree using paging techniques. We show an example of extracting keys using normalization from the from the raw image. Simulation results show that our method improves in flexibility and needs much less storage space.

• Journal of Microbiology and Biotechnology
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• v.19 no.8
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• pp.803-809
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• 2009

Recent evidence has revealed the occurrence of an apoptotic phenotype in Candida albicans that is inducible with environmental stresses such as acetic acid, hydrogen peroxide, and amphotericin B. In the present study, we found that the Chinese herbal medicine Baicalein (BE), which was one of the skullcapflavones, can induce apoptosis in C. albicans. The apoptotic effects of BE were detected by flow cytometry using Annexin V-FITC and DAPI, and it was confirmed by transmission electron microscopy analysis. After exposure to 4 ${\mu}g$/ml BE for 12 h, about 10% of C. albicans cells were apoptotic. Both the increasing intracellular levels of reactive oxygen species (ROS) and upregulation of some redox-related genes (CAP1, SOD2, TRR1) were observed. Furthermore, we compared the survivals of CAP1 deleted, wild-type, and overexpressed strains and found that Cap1p attenuated BE-initiated cell death, which was coherent with a higher mRNA level of the CAP1 gene. In addition, the mitochondrial membrane potential of C. albicans cells changed significantly (p<0.001) upon BE treatment compared with control. Taken together, our results indicated that BE treatment induced apoptosis in C. albicans cells, and the apoptosis was associated with the breakdown of mitochondrial membrane potential.