• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 추계학술대회 논문집 전기물성,응용부문
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• pp.255-258
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• 2001

This paper proposes a new structure of a fiber-optic illuminator using high Lux RGB LEDs. A simulation program, LightTools, is used for the verification of the model. An LED mounting holder containing 74 RGB LEDs is used as a basic part of its light collector. Since the light output level of current LED lamps is still far below that of conventional lamps, it is required to double the right output in order to replace a conventional illuminator with a halogen lamp. An additional cone-type reflector is installed hemispherically and the resulting structure comprises a basic collector unit. To further increase the output two collector units are connected together in series. As the result, the light output increases nearly 70% with compared to a collector with a basic structure. The system efficiency can be increased more than 8 times with compared to conventional one.

• Nuclear Engineering and Technology
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• 제54권6호
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• pp.2120-2134
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• 2022

A hypothetical core destructive accident (HCDA) has received widespread attention as one of the most serious accidents in sodium-cooled fast reactors. This study combined recent advantages in numerical methods to realize realistic modeling of the complex fluid-structure interactions during HCDAs in a full-scale sodium-cooled fast reactor. The multi-material arbitrary Lagrangian-Eulerian method is used to describe the fluid-structure interactions inside the container. Both the structural deformations and plug rises occurring during HCDAs are evaluated. Two levels of expansion energy are considered with two different reactor models. The simulation results show that the container remains intact during an accident with small deformations. The plug on the top of the container rises to an acceptable level after the sealing between the it and its support is destroyed. The methodology established in this study provides a reliable approach for evaluating the safety feature of a container design.

• Asia Marketing Journal
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• 제19권4호
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• pp.37-59
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• 2018

This study investigates the effects of the distribution channel structure on quality decisions under duopoly competition. I considers a set-up in which two retailers compete on product quality and retail price. In the set-up, the integrated retailer has the power to determine the quality of its exclusive product, while the decentralized retailer does not. For the decentralized retailer, the supplier determines product quality. I find that asymmetric pairs of a decentralized channel by one retailer and an integrated channel by the other retailer can be a Nash equilibrium in a simultaneous-channel-choice model. The two retailers select different levels of quality, and this quality competition benefits retailers by softening price competition. In a sequential-channel-choice model, I find that the leader can obtain a first-mover advantage. From the perspective of the supplier, which can decide the distribution channel structure and level of quality, both suppliers choose the decentralized channel in equilibrium.

• 지역사회간호학회지
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• 제7권1호
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• pp.5-17
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• 1996

The purpose of this study was to identify the differences of the outcomes of visiting nursing service (VNS) between the two types by the organizational structure of health centers. Type I referred to 3 health centers with departmentalization for VNS and type II of 3 health centers providing VNS under the subunit of a department. Data were collected from 38 visiting nurses at the six health centers for their perceived formalization, decision-making authority and job satisfaction, 293 clients for the satisfaction level with VNS served and their records analysis for level of quality care and frequency by the contents of VNS through the questionares during the period from June, 1 to August 30, 1993. Data were analyzed using $\chi^2$, F. t or/and Scheffe test. The result were as follows: 1) There were no significant differences in perceived formalization and decision -making authority of visiting nurses between the two types of health centers. 2) There were significant differences in the level of quality care and frequency of the VNS contents between the two types of health centers. 3) There were no significant differences in perceived clients' satisfaction and job satisfaction of the visting nurses between the two types of health centers. From this study, Not only organizational differentiation with the development of job standards and supportive system but also personnel development are suggested when new health care service in health centers begins.

• Journal of Power Electronics
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• 제18권5호
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• pp.1357-1368
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• 2018

In this paper, a novel high gain bidirectional modular dc-dc converter (BMC) with unipolar and bipolar structures for dc network interconnections is proposed. When compared with traditional dc grid-connecting converters, the proposed converter can achieve a high voltage gain with a simple modular transformerless structure. A sub-modular structure for the BMC is proposed to eliminate the unbalanced current stress between the different power units (levels) in the BMC. This can realize current sharing and standardized production and assembling. In addition, phase-interval operation is introduced to the sub-modules to realize low voltage and current ripple in both sides of the converter. Furthermore, two types of bipolar topologies of the sub-modular BMC were proposed to extend its application in bipolar dc network connections. In addition, the control system was optimized for grid-connection applications by providing various control strategies. Finally, simulations of a 3-level unipolar sub-modular BMC and a 4-level bipolar sub-modular BMC were conducted, and a 1-kW experimental 3-level unipolar prototype was developed to verify the effectiveness of the proposed converter.

• 융합보안논문지
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• 제14권7호
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• pp.17-22
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• 2014

MANET은 빠르게 네트워크를 구축할 수 있다는 특징 때문에 많은 분야에서 활용되고 있다. 그러나 무선 네트워크의 특성과 노드들의 이동으로 인해 많은 보안 위협에 노출되어 있다. 특히 그중에서도 라우팅 프로토콜의 취약점을 이용한 공격이 증가하고 있으며 그 피해 또한 매우 증가하고 있는 설정이다. 본 논문에서는 안전한 라우팅 프로토콜 제공을 위한 two-level 인증 구조를 제안하였다. 제안한 기법에서는 네트워크에 참여하는 노드들에 대하여 신뢰도를 기반으로 한 인증 평가를 실시하여 인증서를 발급해주며, 인증서를 발급받은 노드만이 데이터 전송을 수행하게 된다. 그리고 인증서를 발급받은 노드가 데이터 전송시 제어 패킷의 정보와 자신이 관리하는 PIT 정보를 비교 및 분석하여 악의적인 노드들에 대한 탐지를 수행하게 된다. Ns-2 시뮬레이터를 이용하여 본 논문에서 제안한 기법의 성능을 평가하였으며, 실험을 통하여 우수한 성능을 확인하였다.

• Bulletin of the Korean Chemical Society
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• 제34권5호
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• pp.1401-1406
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• 2013

This study tested the feasibility of observing H/D exchange of intact protein by top-down electron capture dissociation (ECD) mass spectrometry for the investigation of protein structure. Ubiquitin is selected as a model system. Local structural information was obtained from the deuteration levels of c and $z^{\cdot}$ ions generated from ECD. Our results showed that ${\alpha}$-helix region has the lowest deuteration level and the C-terminal fraction containing a highly mobile tail has the highest deuteration level, which correlates well with previous X-Ray and HDX/NMR analyses. We studied site-specific H/D exchange kinetics by monitoring H/D exchange rate of several structural motives of ubiquitin. Two hydrogen bonded ${\beta}$-strands showed similar HDX rates. However, the outer ${\beta}$-strand always has higher deuteration level than the inner ${\beta}$-strand. The HDX rate of the turn structure (residues 8-11) is lower than that of ${\beta}$-strands (residues 1-7 and residues 12-17) it connects. Although isotopic distribution gets broader after H/D exchange which results in a limited number of backbone cleavage sites detected, our results demonstrate that this method can provide valuable detailed structural information of proteins. This approach should also be suitable for the structural investigation of other unknown proteins, protein conformational changes, as well as protein-protein interactions and dynamics.

• JSTS:Journal of Semiconductor Technology and Science
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• 제14권5호
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• pp.632-639
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• 2014

Mechanical stress and the vacuum level are the two main factors dominating the quality factor of a resonator operated in the vacuum range 1 mTorr to 10 Torr. This means that if the quality factor of a resonator is very insensitive to the mechanical stress in the vacuum range, it is sensitive to mainly the ambient vacuum level. In this paper, a wafer-level packaged MEMS resonator with a highly vacuum-sensitive quality factor is presented. The proposed device is characterized by a package with out-of-plane symmetry and a suspending structure with only a single anchor. Out-of-plane symmetry helps prevent deformation of the packaged device due to thermal mismatch, and a single-clamped structure facilitates constraint-free displacement. As a result, the proposed device is very insensitive to mechanical stress and is sensitive to mainly the ambient vacuum level. The average quality factors of the devices packaged under pressures of 50, 100, and 200 mTorr were 4987, 3415, and 2127, respectively. The results demonstrated the high controllability of the quality factor by vacuum adjustment. The mechanical robustness of the quality factor was confirmed by comparing the quality factors before and after high-temperature storage. Furthermore, through more than 50 days of monitoring, the stability of the quality factor was also certified.

• 한국전산구조공학회논문집
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• 제35권3호
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• pp.183-190
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• 2022

경주 방폐물 처분시설의 1단계 시설로 건설된 지하 사일로 구조는 2014년에 10만 드럼 규모로 완공되어 현재 운영중에 있다. 지하 사일로 구조는 지름 25m, 높이 50m로써 방폐물을 저장하는 실린더부분과 돔 부분으로 구성되어 있으며, 돔부분은 운영터널과 연결되는 하부 돔 부분과 상부 돔 부분으로 구분할 수 있다. 지하 사일로 구조의 벽체는 철근콘크리트 라이너이고, 두께는 약 1m이다. 본 논문에서는 지하 사일로 구조의 건설과정 및 운영과정의 단계별 유한요소해석을 수행하였다. SMAP-3D 프로그램을 사용하여 2차원 축대칭 유한요소해석을 수행하였다. 2차원 축대칭 유한요소모델의 신뢰성을 검토하고자 3차원 유한요소해석도 수행하였다. 본 논문에서는 지하 사일로 구조의 구조거동을 분석하고 구조적 안전성을 검토결과를 제시하였다.

• 국제학술발표논문집
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• The 7th International Conference on Construction Engineering and Project Management Summit Forum on Sustainable Construction and Management
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• pp.89-98
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• 2017

The floor heating method generally uses a wet construction method including the installation of resilient material, lightweight foam concrete, heating piping, and finishing mortar. Such a wet construction method not only delays other internal finishing processes during curing period for two mortar pouring process, but also has a disadvantage that it is difficult to replace the floor heating layer when it deteriorated because it is integrated with the frame. Dry floor heating construction method can be a good alternative in that it can solve these defects. Conversely, when it applied to the wall structure that is vulnerable to the interlayer noise compared with the column-beam structure, the question about the heavy-impact sound(HIS) insulation performance is raised. Therefore, conventional dry floor heating method is hard to apply to the wall structure apartments. Therefore, for the purpose to improve the applicability of dry floor heating method in wall structure apartments, this study investigated the change of floor impact sound, especially HIS insulation performance which is one of the required performance for the floor structure. This study tried to examine whether the change of heavy-impact sound pressure level(SPL) shows a tendency at the significant level according to the shape and mass of the floor structure. Through filed experiments on wall structure apartment, this study confirmed that the form of the raised floor shows better HIS insulation performance than the fully-supported form. In addition, it was also confirmed that the HIS insulation performance increases with the mass on the upper part. Moreover, this study found the fact that a mass of about 30 kg/m² or more should be placed on the upper structure to reduce the heavy-impact SPL according to the bang machine measuring method. Although this study has a limit due to insufficient experiment samples, if the accuracy of this study is increased, it will contribute to the diffusion of dry floor heating by setting the HIS insulation performance target and designing the dry floor heating structure that meets the target.