• Journal of the Computational Structural Engineering Institute of Korea
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• v.20 no.6
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• pp.691-697
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• 2007

Numerical eigen analysis of beam-like structure can be easily and effectively done by various conventional beam theory-based methods. However, in case of the structures composed of composite-sectioned beams, the application of conventional numerical methods requires one to derive both equivalent material and geometry properties. In the present paper, these equivalent properties are derived by the transformed section method and the test FEM program is coded. The numerical accuracy of the proposed method is verified through the comparison with the ANSYS 3-D model.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.185.2-185.2
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• 2012

저궤도 위성 비행모델 기능시험은 위성체 내부 전장품들 간의 접속 확인과 조립 및 연결상태를 확인하는 시험을 우선적으로 수행한다. 위성체의 전원선 확인 시험은 전기 전자적 조립 시험에서 가장 처음으로 수행하는 시험이다. 전력조절분배장치로부터 전장품 각각의 하드웨어로 공급되는 50볼트 주전원 또는 28볼트 부전원이 정상적으로 공급하게 되는지를 검증한다. 위성체 하니스가 설치된 후, 각각의 하드웨어에 공급되는 전원의 극성 및 연속성 시험을 수행한다. 전력조절분배장치는 태양전지판으로부터 얻어진 전력이 레귤레이터에 의해 정류된 전압을 받아 릴레이나 FET를 통하여 모든 전장품에 전원을 공급하는 주요 장비이다. 전력조절분배장치 내부나 외부 하니스 오류로부터 생길 수 있는 잘못 리드된 전원으로부터 전장품을 보호하기 위하여 하니스를 하드웨어에 연결하기 전에 우선적으로 전원선 확인 시험을 수행한다. 위성체 전원선 확인 시험은 위성체와 기능시험장비를 연결하여 시리얼 명령어를 통해 전력조절분배장치 내부의 FET 동작을 조절하며, FET 동작 상태 및 전장품에 접속되는 입력 단에서의 전압 및 전원 특성 등을 점검한다. 위성체의 주전원 50볼트 라인의 연결도 확인과 부전원 28볼트 라인의 연결도 확인 및 전력제어 유닛 내부 FET의 기능 확인을 수행하며 또한, 전력제어부 외부에 공급하는 28볼트 펄스와 15볼트 펄스를 측정 검증하는 시험을 수행한다.

• Aerospace Engineering and Technology
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• v.9 no.1
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• pp.9-16
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• 2010

In this study, structural analyses were carried out on the composite sandwich panel which was tested under compression loading. In the structural analyses, three types of finite element modelling were considered and linear buckling analysis and nonlinear analysis were performed for each FE-model. Through the analyses, it was found that shell elements for face parts and solid elements for core part were appropriate for the better prediction of the buckling load of the panel. If the material failure of the face is critical than overall buckling of the sandwich panel, the use of one shell element through the thickness direction was suitable in the FE-model for the better predictions of failure location and failure load.

• Journal of the Korea Society for Simulation
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• v.20 no.3
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• pp.49-58
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• 2011

The workloads of facilities and laborers are important for the capacity planning in a factory. They are always referenced whenever a factory develops a new product, increases the production quantity and makes a plan of new investment. There are many measuring methods for estimating the workload effectiveness of facilities and laborers. In this paper, various measuring methods including survey, work sampling, micro-motion study, data gathering from ERP system and simulation, are analyzed for comparing the accuracy of workload. This case study is conducted in a Korean company that produces semiconductor parts like leadframe and packaging substrate.

• Journal of the Korea Safety Management & Science
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• v.20 no.3
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• pp.11-19
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• 2018

This study suggests a model of production information system that can reduce manufacturing lead time and uniformize quality by using DNC S/W as a part of constructing production information management system in the industrial field of the existing marine engine block manufacturing companies. Under the effect of development of this system, the NC machine interface device can be installed in the control computer to obtain the quality information of the workpiece in real time so that the time to inspect the process quality and verify the product defect information can be reduced by more than 70%. In addition, the reliability of quality information has been improved and the external credibility has been improved. It took 30 minutes for operator to obtain, analyze and manage the quality information when the existing USB memory is used, but the communication between the NC controller computer and the NC controller in real time was completed to analyze the workpiece within 10 seconds.

• Information and Communications Magazine
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• v.29 no.11
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• pp.3-10
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• 2012

정보통신기술의 급속한 발전으로 인해 인터넷은 사회 전분야를 변화시키고 있으며 다양하고 폭넓은 이용 행태에 따라 지금 이 순간에도 엄청난 데이터를 생산해 내고 있다. 대부분의 인터넷 데이터는 제한적인 활용 이외 단순 생성과 소멸을 반복해 왔으나 최근 들어 빅데이터(Big Data)라는 핵심 키워드의 부상으로 인터넷 데이터에 대한 관심이 고조되고 있다. 과거에도 데이터 마이닝(Data Mining), 비즈니스 인텔리전스(Business Intelligence), 라이프 로그(Life Log) 등을 통해 데이터 기반의 부가가치를 창출하려는 노력은 시도되어 왔다. 그렇다면 왜 다시 빅데이터라는 이름으로 재부상 하고 있는 것일까? 이는 정보통신기술의 진화와 맞물려 새롭게 부상하고 있는 인터넷 글로벌 기업들이 지속적으로 생성되는 다양한 데이터들을 확보하고 그 속에서 숨겨진 가치를 찾고 인사이트(Insight)를 도출하려는 시도를 통해 데이터 보유와 활용이 새로운 경쟁력이 될 수 있음을 입증하고 있기 때문이다. 이러한 시도들은 빅데이터를 다양한 분야에서 중요한 이슈로 자리매김하게 하고 있다. 이러한 상황에서 과연 우리는 빅데이터 시대를 어떻게 리드하고 무엇에 집중하여야 할 것인가? 본 연구는 현재 뜨거운 감자로 부상한 빅데이터를 정의하고 빅데이터 시장분석, 사례분석, 정책분석을 통해 시사점을 도출하여 향후 다가올 빅데이터 시대의 국가경쟁력 확보를 위한 빅데이터 이니셔티브(Initiative)의 필요성과 중점 방향 등을 제언하고자 한다.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.52 no.8
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• pp.452-461
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• 2003

The reliability and accuracy of the information on control rod position are very important to the reactor safety and the design of the core protection system. A survey on the RSPT(Reed Switch Position Transmitter) type control rod position indicator system and its actual implementation in the existing nuclear power plants in Korea was performed first. The control rod position indicator having the high performance for SMART was developed on the basis of RSPT technology identified through the survey. The arrangement of permanent magnet and reed switches is the most important procedure in the design of control rod position indicator. The hysteresis of reed switches is one of the important factors in a repeat accuracy of control rod position indicator as well. This paper investigates efficiency of the magnetic flux concentrator and the hysteresis using FEM and verified differences in physicals characteristics by comparing the results of FEM and those of the experiment. As a result, it is shown that the characteristics of prototype control rod position indicator have a good agreement with the results of FEM.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.51 no.12
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• pp.670-675
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• 2002

AC loss is an important issue in the design of high-T$_{c}$ superconducting Power cables. The cables consists of a number of Bi-2223 tapes wound on a former. In such cables tapes have different critical current characteristics intrinsically. And they are electrically connected to each other and current leads by soldering. These make loss measurements considerably complex, especially for short samples of laboratory size. Special cautions are required in the positioning of voltage leads for measuring the true loss voltage. In this work the at losses in a single layer model cable have been experimentally investigated for different contacts and arrangements of voltage leads. The results show that the losses are not dependent on both arrangements and contact positions of the voltage leads. This implies that loss flux is only in a cylindrical conductor section. The measured losses also agree well with those based on a monoblock model and are independent of frequencies. This means that the measured AC loss of the model cable is purely hysteretic in nature.e.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.4 no.4
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• pp.311-317
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• 2011

Recently, RFID is substituted for bar codes according to advance in the ubiquitous computing environments, but the RFID system has several problems such as security and privacy because it uses radio frequencies. Firstly, unauthorized reader can easily read the ID information of any Tag. Secondly, Attacker can easily fake the legitimate reader using the collected Tag ID information,such as the any legitimate tag. This paper proposed improved RFID authentication protocol based on SSG. SSG is organized only one LFSR and selection logic. Thus SSG is suitable for implementation of hardware logic in system with extremely limited resources such as RFID tag and it has resistance to known various attacks because of output bit stream for the use as pseudorandom generator. The proposed protocol is secure and effective because it is based on SSG.

• The Transactions of the Korean Institute of Power Electronics
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• v.10 no.6
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• pp.618-625
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• 2005

This paper has achieved that an optimal design and experiments of heater and cathode of electron gun that serve to embody high current density in CRT display. For the high brightness, high resolution and larger size in CRT display, high current density of electron gun is indispensible. An Impregnation style cathode is used, and must heighten operating temperature of heater to get high current density for this, it is proportional hereupon and power dissipation increases. In this paper, to get low power cathode with high current density, There are produced and tested sample that differ lead type of heater, coating method, the pitch and number of winding of the first and second coiling in the heat emission area for the low power design of high current density cathode heater in this paper.