• 한국항공우주학회지
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• 제50권9호
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• pp.609-616
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• 2022

메쉬 반사판 안테나의 성능은 반사판 표면의 형상 오차에 크게 의존하게 된다. FDM(Force Density Method)을 이용하여 반사판 케이블 네트의 형상설계 연구가 수행되고 있다. 하지만 결정된 형상 일부에 반사판 실효면적의 감소가 발생하고, 케이블의 기하학적 비선형을 고려한 변형 해석은 불가능하다. 본 연구에서는 기하학적 특성을 고려한 케이블 네트 형상설계 방법론을 제시하고 설계된 형상의 실효성을 검증한다. 기하학적 비선형성을 고려한 케이블 네트의 유한요소 모델을 개발한다. 경계조건의 하중 변화에 따른 형상변형 해석을 통하여 케이블 네트 형상 설계변수 특성을 제시하고자 한다.

• 반도체디스플레이기술학회지
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• 제15권4호
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• pp.61-66
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• 2016

This paper presents the implementation for a network structure of railway cars using a point to point communication. Most of network's representative specifications for a train are the FIP (Field Bus), MVB (Multifunction Vehicle Bus), CAN and WTB (Wire Train Bus) which is used by ALSOM, SIEMENS and BOMBADIER as major in this field. These networks in a physical layer use a multi-drop method, connected from $1^{st}$ car to $n^{th}$ car of a train through a cable without any extra services such as an electric part, amplifier. However waveforms which is passed through a long cable in the multi-drop are distorted by a capacitance or resistance of the cable or environments. Also since using a cable connected directly from $1^{st}$ car to $n^{th}$ car, if over two trains make double head, it isn't easy to distinguish ID for each railway cars. So by using the point to point network per each car, it is able to reduce a distortion. Also since reducing distortion, this communication speed can be been higher and transmit and receive any packets more stably. Using proposed token in a packet, this can make ID per each railway car automatically. Finally experimental results show the good performance and effectiveness of the proposed method.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 C
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• pp.2057-2059
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• 2000

The underground transmission system has been internationally developing the voltage class of which increase to realizing high reliability and efficiency. Under this situation, if a company don't do much labor to elevating one's technology, the company will be hard to compete against other companies in trade. Our company has successfully developed 275kV oil-filled cable and its accessory in 1999 for Malaysia project, which was based on accumulated technological know-how, which is the highest voltage level among awarded oversea underground transmission networks in Korea. The power cable and its accessories were subjected to type approval test in accordance with IEC 60141-1 and TNB tender documents. This paper describes the main features of the type approval tests of the cable and its accessories.

• 한국전자파학회논문지
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• 제28권11호
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• pp.872-879
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• 2017

본 논문은 direct digital synthesizer, 연산 증폭기 및 이득/위상 검출기로 구성된 소형 임피던스 분석기를 사용하여 차분 주파수 영역 반사 계측을 기반으로 한 케이블 결함 모니터링 시스템을 제시한다. 제안된 시스템은 주파수 영역 반사계측을 위한 고가의 벡터 네트워크 분석기를 저비용으로 대체할 수 있으므로, 장기간 동안 다중 지점을 모니터링하는 센서 네트워크 구성이 가능하다. 이 시스템의 성능은 전원 케이블의 결함 지점을 진단하는 실험을 통해 검증하였다.

• KIEE International Transactions on Power Engineering
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• 제3A권2호
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• pp.63-69
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• 2003

The necessity of compact high temperature superconducting cables is more keenly felt in densely populated metropolitan areas. Because the compact high-temperature superconducting cables can be installed in ducts and tunnels, thereby reducing construction costs and making the use of underground space more effective, the effect of introducing it to the power system will be huge. Seoul, Korea, is selected as a review model for this paper. The loads are estimated by scenario based on a survey and analysis of 345kV and 154kV power supply networks in this area. Based on this, the following elements for an urban transmission system are examined. (1) A method of constructing a model system to introduce high-temperature superconducting cables to metropolitan areas is presented. (2) A case study is conducted through the analysis of power demand scenarios, and the amount of high-temperature superconducting cable to be introduced by scenario is examined. (3) The economy involved in expanding existing cables and introducing high-temperature superconducting cables(ducts or tunnels) following load increase in urban areas is examined and compared., and standards for current cable ducts are calculated. (4) The voltage level that can be accommodated by existing ducts is examined.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2001년도 봄 학술발표회 논문집
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• pp.233-240
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• 2001

Artificial neural networks(ANN) have been exploited where the relationship among information is very complicated and nonlinear. It is appropriate to computerize the information and knowledge used in the preliminary design stage where it lacks of formality of representation of designers' experience and intuition. However, most designers start the preliminary design stage with very little information. Therefore, the ANN model for this stage must be designed to have input much less than output. This case usually causes big troubles such as in learning time, convergence and reliability of solutions. To address this problem, this paper proposes multi-level neural networks for progressive structural design considering that all the design information can not be obtained at a time but are growing gradually. The use of multi-level networks developed in this paper has been proved its validity by applying it to the preliminary design of cable-stayed bridges.

• 한국전산구조공학회논문집
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• 제15권2호
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• pp.261-270
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• 2002

신경망은 설계자의 경험과 통찰력과 같은 비정형적 정보에 의존하는 초기 구조설계단계의 시스템화에 매우 적합하다. 초기 구조설계단계를 시작하는 시점에서는 설계정보가 매우 적음을 생각해 볼 때, 신경망 모델은 제한적인 적은 정보를 입력으로 하고 상대적으로 훨씬 많은 출력을 가지도록 설계되어야 한다. 그러나, 이러한 상황은 신경망 학습시 학습속도, 수렴, 출력 값의 신뢰성등 여러 가지 문제점을 초래한다. 본 연구에서는 이러한 문제점을 해결하기 위하여 설계 정보가 점진적으로 증가하는 흐름을 가지고 있다는 점에 착안해서 다단계 신경망을 제시하고, 이를 토대로 사장교 초기 구조설계시스템에 대한 원형을 구현하였다. 본 연구결과 초기 구조설계단계 전체에 대해서 하나의 신경 망으로 설계하는 것 보다 다단계 신경 망으로 나누어서 동일한 작업을 수행하도록 하는 것이 훨씬 유리하다.

• Smart Structures and Systems
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• 제6권3호
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• pp.263-275
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• 2010

In the last decade, wireless sensor networks have emerged as a promising technology that could accelerate progress in the field of structural monitoring. The main advantages of wireless sensor networks compared to conventional monitoring technologies are fast deployment, small interference with the surroundings, self-organization, flexibility and scalability. These features could enable mass application of monitoring systems, even on smaller structures. However, since wireless sensor network nodes are battery powered and data communication is the most energy consuming task, transferring all the acquired raw data through the network would dramatically limit system lifetime. Hence, data reduction has to be achieved at the node level in order to meet the system lifetime requirements of real life applications. The objective of this paper is to discuss some general aspects of data processing and management in monitoring systems based on wireless sensor networks, to present a prototype monitoring system for civil engineering structures, and to illustrate long-term field test results.

• 대한산업공학회지
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• 제34권2호
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• pp.205-215
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• 2008

convergence networks (BcN). The problem seeks to minimize the total cost of switch and cable while satisfying the requirement of demand and quality of service (QoS). We develop mixed integer programming models to obtain the optimal switch location of the access network. We develop a Tabu Search (TS) heuristic algorithm for finding a good feasible solution within a reasonable time limit. We propose real networks with up to 25 nodes and 180 demands. In order to demonstrate the effectiveness of the proposed algorithm, we generate lower bounds from nonlinear QoS relaxation problem. Computational results show that the proposed heuristic algorithm provides upper bounds within 5% optimality gap in 10 seconds.

• ETRI Journal
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• 제28권5호
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• pp.631-637
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• 2006

In this paper we study the optimization issues of ring networks employing novel parallel multi-granularity hierarchical optical add-drop multiplexers (OADMs). In particular, we attempt to minimize the number of control elements for the off-line case. We present an integer linear programming formulation to obtain the lower bound in optimization, and propose an efficient heuristic algorithm called global bandwidth resource assignment that is suitable for the design of large-scale OADM networks.