• 한국컴퓨터정보학회논문지
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• 제23권10호
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• pp.173-180
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• 2018

In this paper, we analyzed key keywords and research themes in the field of defense research using keyword network analysis and tried to grasp the whole knowledge structure. To do this, we extracted data from 2,165 research data from defense related research institutes from 2010 to 2017 and applied the Pareto rule to the number of abstracts of words and the number of links between words, We extracted a total of 2,303 words based on the criterion and extracted 204 final key words through component analysis. By analyzing the centrality and cohesiveness through these key words, we confirmed the concept of core research in the defense field and derived a total of 7 large groups and 16 small groups of each group in the knowledge structure of the defense area.

• Journal of Magnetics
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• 제22권2호
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• pp.333-343
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• 2017

A rotating magnetic field (RMF) ${\Phi}_1-{\Phi}_2$ model was developed in consideration of the skin effect. The rotating magnetic field's induced three-dimensional flow was simulated numerically, and the influence of the skin effect was investigated. The rotating magnetic field drives the rotating convection in the azimuthal direction, and a secondary convection appears in the radial-meridional direction. The results indicate that ignoring the skin effect results in a smaller azimuthal velocity component and larger radial and axial velocity components, and that the deviation becomes more obvious with the larger dimensionless shielding parameter K.

• Nuclear Engineering and Technology
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• 제39권2호
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• pp.103-110
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• 2007

The High Temperature Gas-cooled Reactor (HTGR) possesses inherent safety features and is recognized as a representative advanced nuclear system for the future. Based on the success of the HTR-10, the long-time operation test and safety demonstration tests were carried out. The long-time operation test verifies that the operation procedure and control method are appropriate for the HTR-10 and the safety demonstration test shows that the HTR-10 possesses inherent safety features with a great margin. Meanwhile, two new projects have been recently launched to further develop HTGR technology. One is a prototype modular plant, denoted as HTR-PM, to demonstrate the commercial capability of the HTGR power plant. The HTR-PM is designed as $2{\times}250$ MWt, pebble bed core with a steam turbine generator that serves as an energy conversion system. The other is a gas turbine generator system coupled with the HTR-10, denoted as HTR-10GT, built to demonstrate the feasibility of the HTGR gas turbine technology. The gas turbine generator system is designed in a single shaft configuration supported by active magnetic bearings (AMB). The HTR-10GT project is now in the stage of engineering design and component fabrication. R&D on the helium turbocompressor, a key component, and the key technology of AMB are in progress.

• Structural Engineering and Mechanics
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• 제20권6호
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• pp.655-672
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• 2005

Seismic random responses due to the wave passage effect are extensively investigated by using the pseudo excitation method (PEM). Two examples are used. The first is very simple but also very informative, while the second is a realistic suspension bridge. Numerical results show that the seismic responses vary significantly with wave speed, especially for low velocity or large span. Such variations are not monotonic, especially for flexible structures. The contributions of the dynamic and quasi-static components depend heavily on the seismic wave velocity and the natural frequencies of structures. For the lower natural frequency cases, the dynamic component has significant effects on the dynamic responses of the structure, whereas the quasi-static component dominates for higher natural frequencies unless the wave speed is also high. It is concluded that if insufficient data on local seismic wave velocity is available, it is advisable to select several possible velocity values in the seismic analysis and to choose the most conservative of the results thus obtained as the basis for design.

• Applied Biological Chemistry
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• 제48권3호
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• pp.292-295
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• 2005

Branched methyl group을 가지는 아프리카산 난(Aerangis confusa, Aerangis kirkii) 꽃의 천연향기성분인 methyl 3-methyloctanoate를 값싼 미생물 발효산물인 itaconic acid를 출발 물질로 하여 제조한 branched metyl group을 부분구조로 가지는 2-methyl-1,4-butandiol를 중간체로 하여 전 공정 9단계로 합성하였다. 최종 향기성분 metyl 3-methyloctanoate의 methyl ester대신 다양한 알킬 ester 화합물을 합성하여 그 향을 비교한 결과 서로 상이한 향 특성을 나타내므로 화장품이나 식품산업에 있어서 유용한 향료조성물의 첨가소재로 개발 가능하리라 사료된다.

• 한국통신학회논문지
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• 제18권3호
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• pp.410-424
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• 1993

본 논문에서 디지털 신호처리를 위한 시스톨릭 배열과 비동기 제어 설계를 새로운 기법에 대하여 작성하였다. 특히, 배열안에 사전에 데이터를 입력하는 방법이나, 전체적인 제어와 같은 예전 방법과 다르게 최적의 성능을 성취할 수 있는 간단하고 내부적인 상호 연결을 갖는 시스톨릭 배열을 제안하고 있다. 이와 같은 디지털 신호처리에 대한 비동기 시스톨릭 배열은 일정하게 설계된 배열에서 비교한 경우 전체 계산 시간을 상당히 줄일 수 있음을 비교를 통해서 다루었다. 비동기 시스톨릭 배열의 중요한 요소는 입력 데이터를 적절하고 효율적으로 제어할 수 있는 통신 프로토콜 설계이다. 마지막으로, Transputer의 병렬 컴퓨터 언어인 OCCAM를 이용하여 배열의 효율성을 비교 분석하고 시뮬레이션의 결과를 보였다.

• 한국정보통신학회논문지
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• 제9권6호
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• pp.1316-1322
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• 2005

인터넷을 통한 전자상거래와 전자서명기술이 대두되면서 부각된 기술이 PKI(Public Key Ifrastructure)이다. PKI는 암호화기반기술에 있어서 여러 가지 새로운 표준들을 가져왔다. 그러나 이 같은 표준화가 활발히 진행되고 있음에도 PKI를 응용한 솔루션들은 가격이 비싸고 느린 단점들이 지적되고 있다. 현재 PKI를 포함한 암호화기술의 주된 관심이 빠른 속도와 보다 향상된 보안성이라고 한다면 이 같은 문제들은 심각한 문제들이라고 할 수 있다. 본 논문은 기존의 PKI구조에서 가지는 몇 가지 문제를 개선하여 짧은 메시지 통신이나 단순 방식 암호화 통신에 단순하고 쉽게 사용될 수 있는 통신 컴포넌트를 설계하고 구현하였다.

• 제어로봇시스템학회논문지
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• 제11권5호
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• pp.471-475
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• 2005

Recently, development of digital technology is occupying a large part of multimedia information like character, voice, image, video, etc. Research about video indexing and retrieval progresses especially in research relative to video. This paper proposes the novel notation in order to retrieve MPEG video in the international standards of moving picture encoding For realizing the retrieval-system, we detect DCT DC coefficient, and then we obtain shot to apply MVC(Mean Value Comparative) notation to image constructed DC coefficient. We choose the key frame for start-frame of a shot, and we have the codebook index generating it using feature of DC image and applying PCA(principal Component Analysis) to the key frame. Also, we realize the retrieval-system through similarity after indexing. We could reduce error detection due to distinguish shot from conventional shot detection algorithm. In the mean time, speed of indexing is faster by PCA due to perform it in the compressed domain, and it has an advantage which is to generate codebook due to use statistical features. Finally, we could realize efficient retrieval-system using MVC and PCA to shot detection and indexing which is important step of retrieval-system, and we using retrieval-system over the internet.

• Journal of Electrical Engineering and Technology
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• 제13권4호
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• pp.1697-1704
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• 2018

As a key component of lighting location system (LLS) for lightning warning, the atmospheric electric field measuring is required to have high accuracy. The Conventional methods of the existent electric field measurement meter can only detect the vertical component of the atmospheric electric field, which cannot acquire the realistic electric field in the thunderstorm. This paper proposed a three dimensional (3D) electric field system for atmospheric electric field measurement, which is capable of three orthogonal directions in X, Y, Z, measuring. By analyzing the relationship between the electric field and the relative permittivity of ground surface, the permittivity is calculated, and an efficiency 3D measurement model is derived. On this basis, a three-dimensional electric field sensor and a permittivity sensor are adopted to detect the spatial electric field. Moreover, the elevation and azimuth of the detected target are calculated, which reveal the location information of the target. Experimental results show that the proposed 3D electric field meter has satisfactory sensitivity to the three components of electric field. Additionally, several observation results in the fair and thunderstorm weather have been presented.

• Design & Manufacturing
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• 제16권4호
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• pp.40-45
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• 2022

The EV electric vehicle market is growing rapidly worldwide. An electric vehicle means a vehicle that uses energy charged through an electricity source as power. The precision of the press is important to mass-produce the drive motor, which is a key component of the electric vehicle. The size of the driving motor is increasing, and The size of the mold is also growing. In this study, the precision of large high-speed presses for mass production of driving motors was measured. A study was conducted on the measurement method of press and the analysis of measurement data. A drive motor is a component that transmits power by converting electrical energy into kinetic energy. EV driven motors have key material properties to improve efficiency. The material properties are the thickness of the material. As a method for improving performance, use a 0.2mm thin steel sheet. Mold is also becoming larger. As the mold grows, the size of the high-speed press for mass production of the driving motor is also increasing. Also, the precision of the press is the most important because it uses a thin iron plate material. So the importance of large press precision is being emphasized. In this study, the effect of large high-speed press structure on precision was verified