• 한국국방경영분석학회지
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• 제31권2호
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• pp.105-115
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• 2005

To ensure interoperability among TADILs, we need inter-operational system of tactical data link that allows sharing of specific, planned information among different TADILs. In this paper, we have proposed the design of a conceptual software architecture of inter-operational system. For developing of a conceptual software architecture, we analyze the actual condition of ADSI used in the US military and identify functions and quality-attributes. Based on these factors, we design the conceptual software architecture for inter-operational system of tactical data link using Attribute-Driven Design(ADD) method. ADD is consist of three phases - choose the module to decompose, refine the module, repeat the steps for every module that needs further decomposition. To evaluate of ADD results, we apply the Software Architecture Analysis Method(SAAM) which is consist of making evaluation scenarios, choosing indirect scenarios, evaluation scenarios' interaction, and creating an overall evaluation. Through the evaluation, we verify the conceptual software architecture of inter-operational system.

• Journal of Power Electronics
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• 제11권5호
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• pp.677-687
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• 2011

In this paper a cycloconverter-type high frequency transformer link inverter with a reduced switch count is analyzed and designed. The proposed topology consists of an H-bridge inverter at the transformer's primary side and a cycloconverter with three bidirectional switches at the secondary. All of the switches of the cycloconverter operate in non-resonant zero voltage and zero current switching modes. To overcome a high voltage surge problem resulting from the transformer leakage inductance, phase angle control based on natural commutation is employed. The effectiveness of the proposed inverter is verified by constructing s 750W prototype. Experimentally, the inverter is able to supply a near sinusoidal output voltage with a total harmonic distortion of less than 1%. For comparison, a PSpice simulation of the inverter is also carried out. It was found that the experimental results are in very close agreement with the simulation.

• 정보처리학회논문지:컴퓨터 및 통신 시스템
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• 제8권3호
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• pp.73-78
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• 2019

무선 네트워크에서 토폴로지의 빈번한 변화로 노드 간 링크 단절과 경로재설정이 발생하여 네트워크 내에 제어메시지 과부하와 같은 문제점들이 발생한다. 본 연구에서는 링크 단절과 제어 메시지 과부하와 같은 문제점을 해결하기 위하여 무선 네트워크 환경에서 주변 노드 탐색과정, 경로 탐색과정, 경로 관리과정의 3단계로 경로 설정을 수행하고 경로 관리 과정에서 존 마스터가 수집한 라우팅 테이블의 정보를 이용하여 링크 안정성 값을 산출한다. 그리고 산출 된 링크 값을 존 마스터가 모니터링 하여 임계 값 이하로 되면 링크 단절로 예측하고 해당 송수신 노드에게 경로 재설정을 수행하게 된다. 제안한 기법은 이동 노드 수 변화에 따른 데이터 처리량, 평균 경로 설정 시간 및 이동 노드의 속도 변화에 따른 데이터 처리량에서 기존의 OLSR 프로토콜보다 성능 향상을 나타내었다.

• 한국도로학회논문집
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• 제10권1호
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• pp.145-154
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• 2008

본 연구의 목적은 출발시각기준 실시간 링크통행시간 추정정보의 질을 평가하는 것이다. 이에 본 연구는 통행시간 정보의 질을 정확성(추정오차)과 신속성(시간처짐) 측면에서 평가하였다. 그리고 통행시간 정보의 질과 링크길이 및 혼잡수준과의 관계를 규명하였다. 분석결과, 출발시각기준 실시간 링크통행시간 추정정보의 정확성과 신속성은 서로 상충관계임을 알 수 있었다. 또한 정확성을 나타내는 '추정오차' 는 계통오차(systematic error)와 혼잡수준을 반영하는 평균자승오차(MSEE)로 구성되는 것으로 분석되었다 시간처짐은 '최소시간처짐', '혼잡에 의한 시간처짐', '갱신간격에 의한 시간처짐'으로 구분하여 평가하였다. 이를 실제 AVI자료에 적용한 결과, 링크길이와 혼잡수준에 관계없이 추정오차가 5%일 때, 시간처짐은 약 10분 정도 발생하는 것으로 나타났다.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2008년도 정기 학술대회
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• pp.100-103
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• 2008

Recently Development of construction system that subjective operators share and control information efficiently based on the three-dimensional space and design information throughout life cycle of construction project is progressing dynamically. In case of civil structures which are infrastructure, Demand for structure of complex system which has multi-functions such as super and smart bridges and express rails is increasing and system development which computerizes and integrates process of structure design is in need. For that, research about link way between three dimensional modeling data and structure analysis programs should be preceded. In this research, therefore, research about interface design between three dimensional virtual modeling data to automate efficient civil-structure-design and nonlinear finite element analysis program which is made up of reinforced concrete material model that express material's character clearly.

• Journal of Astronomy and Space Sciences
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• 제37권1호
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• pp.11-18
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• 2020

Satellite optical communication has gained significant attention owing to its many quality features (e.g., a larger bandwidth, license free spectrum, higher data rate, and better security) compared to satellite microwave communication. Various experiments have been performed during many space missions to demonstrate and characterize inter-satellite links, downlinks, and uplinks. Korea has also planned to establish an experimental communication system using a geostationary earth orbit (GEO) satellite and the Geochang station as an optical ground station for low Earth orbit (LEO)-to-ground optical relay links. In this study, the performance of inter-satellite communication links and downlinks was investigated for the new Korean experimental communication system in terms of link margin, bit error rate (BER), and channel capacity. In particular, the performance of the inter-satellite links was analyzed based on the receiving apertures and the transmitting power, while that of the downlink was analyzed in terms of atmospheric turbulence conditions and transmitting power. Finally, we discussed two system parameters of receiving aperture and transmitting power to meet the three criteria of link margin, BER, and channel capacity.

• 전력전자학회논문지
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• 제26권3호
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• pp.205-213
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• 2021

Due to the advantage of reducing the voltage applied to the switch semiconductor, the input series and output parallel combination is widely used in systems with high input voltage and large output current. On the other hand, the LLC converter is widely used as a high-efficiency power converter, and when connected by ISOP combination, there is a possibility that input voltage imbalance may occur due to a mismatch of passive devices. To avoid damaging the switching device, this study analyzed the DC-link voltage imbalance of a high-capacity supply using an ISOP LLC converter. In addition, the case where DC-link unbalance control was applied and the case not applied was analyzed respectively. Based on this analysis, an initial start-up algorithm was proposed to prevent input power semiconductor device damage due to DC-link over-voltage. The effectiveness of the proposed algorithm has been verified through simulations and experiments.

• 한국공간구조학회논문집
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• 제22권4호
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• pp.39-48
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• 2022

The energy dissipation of inverted V-type eccentric steel braced frames can be achieved through the yielding of a slit link, through yielding of a number of strips between slits when the frame is subjected to inelastic cyclic deformation. On the other hand, the development of seismic resistance system without residual deformation is obtained by applying the superelasdtic shape memory alloy (SMA) material into the brace and link elements. This paper presents results from a systematic three-dimensional nonlinear finite element analysis on the structural behavior of the eccentric bracing systems subjected to cyclic loadings. A wide scope of structural behaviors explains the horizontal stiffness, hysteretic behaviors, and failure modes of the recentering eccentric bracing system. The accurate results presented here serve as benchmark data for comparison with results obtained using modern experimental testing and alternative theoretical approaches.

• Journal of Power Electronics
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• 제3권1호
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• pp.1-9
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• 2003

This paper presents a performance analysis of typical Auxiliary Resonant Commutation Snubber-assisted three phase voltage source soft switching inverter which can operate under a condition of Zero Voltage Switching (ZVS) using a digital control scheme which is suitable for high power applications compared with resonant DC link snubber assisted soft switching inverter. The system performances of this inverter are illustrated and evaluated on the basis of experimental results.

• Journal of Power Electronics
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• 제12권6호
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• pp.925-934
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• 2012

Three-phase controlled converters have many applications in the utility interfacing of renewable energy sources and adjustable speed drives as a rectifier or inverter. The utility line currents of these converters have a high harmonic distortion, which is more than the harmonic standards. This paper introduces a new technique for circulating the third harmonic currents from the dc-link to the line currents to reduce their harmonic contents. The proposed system uses a single-phase PWM converter to control the angle and amplitude of the injection current for each of the firing angle of a three-phase converter. A detailed analysis is introduced to achieve a relationship between the firing angle of the three-phase controlled converter and the power angle of the PWM converter. In addition, a detailed design for the other injection path components is introduced. A simulation and experimental work is introduced to prove the mathematical derivations. Analysis, simulation and experimental results prove the superiority of the proposed technique.