• Journal of the Korea Academia-Industrial cooperation Society
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• v.4 no.4
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• pp.380-386
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• 2003

As Internet is spreaded widely, the virtual communities among people with the same interest and hobby are dynamically created. The exchange of fruitful opinion and information makes them to be closed, not only with the help of the messaging system but also wireless terminals. The messaging system is a core technology supporting the global community services like chatting, messenger, short message services, and file sharing services. The paper focus on the design of software architecture for messaging system and the engineering model for QoS support.

• Journal of Advanced Marine Engineering and Technology
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• v.31 no.4
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• pp.335-342
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• 2007

A propulsion and lift shafting system in an air cushion vehicle is flexible multi-elements system which consists of two aeroderivative gas turbines with own bevel gears, four stage lift fan reduction gear, two stage propulsion reduction gear air propellers and high capacity of lifting fans. In addition, the system includes the multi-branched shafting with multi-gas turbine engines and thin walled shaft with flexible coupling. Such a branched shafting system has very intricate vibrating characteristics and especially, the thin walled shaft with flexible couplings can lower the torsional natural frequencies of shafting system to the extent that causes a resonance in the range of operating revolution. In this study, to evaluate vibrational characteristics some analytical methods for the propulsion and lift shafting system are studied. The analysis, including natural frequencies and mode shapes, for five operation cases of the system is conducted using ANSYS code with a equivalent mass-elastic model.

• Proceedings of the IEEK Conference
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• 2000.11a
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• pp.389-392
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• 2000

Electronics and Telecommunications Research Institute (ETRI) developed the Ka-band satellite communications payload. This system is able to provide a high data rate communication service with a bandwidth of 200 MHz, a wideband digital flunking services up to 155 Mbps and asymmetrical internet multimedia service. The system employs the common receive/transmit antenna and the 2-for-1 redundant scheme for the LNA-Downconverters. The different types of high power amplification, TWTA for one chain and SSPA for the other chain, are used lot the variety of experimental options. For the reliable test of the payload, EGSE was also developed. The parametric RF tests were carried out in order to measure the performance of Ka-band communication subsystem, in most case the results of RF performance test complied the payload requirement.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1289-1294
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• 2008

Electrostatic discharge(ESD) phenomenon is a serious reliability concern. It causes approximately most of all field failures of IC. To quality the ESD immunity of IC product, there are some test methods and standards developed. ESD events have been classified into 3 models, which are HBM, MM and CDM. All the test methods are designed to evaluate the ESD immunity of IC products. This study provides an overview among ESD test methods on ICs and an efficient ESD stress method. We have estimated on all pin combination about the positive and negative ESD stress. We make out the weakest stress mode. This mode called a worst-case mode. We proposed that positive supply voltage pin and I/O pin combination is efficient because it is a worst-case mode.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.174-179
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• 2004

To maintain design-knowledge database and manage configuration for requirement of performance test and safety standard of High Speed Railroad, It is established that managment system of performance test and safety standard and then constructed that design-knowledge database and documented a performance test and safety specification for supporting performance test and safety system using computer-aided tool.

• Electronics and Telecommunications Trends
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• v.11 no.1 s.39
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• pp.49-64
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• 1996

Computer-Aided Control Engineerig(CACE) 프레임워크는 컴퓨터 제어시스템의 개발비용과 신뢰성에 대한 위기에 대처하여, 제어시스템 엔지니어링 분야의 독립적인 소프트웨어 패키지들을 상호 호환성 있게 통합하여 컴퓨터 제어시스템의 모델링과 구현, 유지보수 및 소프트웨어 재사용에 이르는 라이프사이클 전단계에 걸쳐 일관적으로 사용될 수 있어야 한다. 이러한 개념의 개방형 통합 소프트웨어 패키지 운영체제가 광범위한 응용분야에서 재사용될 수 있도록 하기 위해서는 다음과 같은 5가지 서비스 클래스를 제공하는 프레임워크라는 기반구조에 의해 개발되어야 한다. 프레임워크에서 제공하려는 서비스들은 여러 응용분야의 소프트웨어 패키지들을 통합적으로 운영하기 위하여 필수적으로 요구되는 서비스 개념으로서 데이터베이스 서비스, 모델정의 서비스, 태스크 운영 서비스, 사용자 대화 서비스, 프로세스 통신을 위한 메시지 서비스들이 존재한다.

• Korean Journal of Remote Sensing
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• v.12 no.2
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• pp.97-110
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• 1996

In this paper, we describe the structure, function, and the operation method of the high resolution CCD camera system on the KITSAT-3, which will be launched in 1998. We have developed the camera system with the University of Stellenbosch in the Republic of South Africa. Currently we are doing the environmental test for the engineering model of the camera system. The main purposes of the system are the technology acquisition and operation test. The around resolution of the system is 15 m at the 800 Km earth orbit.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.05a
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• pp.294-295
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• 2018

Nowadays, the construction industry utilizes 3D models in the designing process, on which research is being conducted to establish an automated system for project cost estimation in connection with information related to construction such as material unit costs and wages, beyond the level of design interference review and construction quantity estimation. In this process, the project cost is estimated in connection with unit price data after takeoff the quantity based on the 3D model attributes and data types. A way to reduce cost and risk would be first developing prototypes of some of essential buildings and works, comparing and validating the outcomes, and then extending to the whole scope, because estimates differ on the basis of the scope and level of 3D design models as well as the data accuracy. This study analyzes case studies of project cost estimation by computing the quantity on the basis of 3D model in the construction industry and explores methodologies and management measures applicable for estimating nuclear power plant construction project costs.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.9
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• pp.799-804
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• 2016

Broadband powerline communication (BPLC) uses distribution lines as a medium for achieving effective bidirectional data communication along with electric current flow. As the material characteristics of power lines are not good at the communication channel, the development of power line communication (PLC) systems for internet, voice, and data services requires measurement-based models of the transfer characteristics of the network suitable for performance analysis by simulation. In this paper, an analytic model describing a complex transfer function is presented to obtain the attenuation and path parameters for a multipath power line model. The calculated results demonstrated frequency-selective fading in multipath channels and signal attenuation with frequency, and were in good agreement with the experimental results. Inductive coupling units are used as couplers for coupling the signal to the power line to avoid physical connections to the distribution line. The inductance of the ferrite core, which depends on the frequency, determines the cut-off frequency of the inductive coupler. Coupling loss can be minimized by increasing the number of windings around the coupler. Coupling efficiency was improved by more than 6 dB with three windings compared to the results obtained with one winding.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.3B
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• pp.311-319
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• 2006

A bed level change model(SED-FLUX) is introduced based on the realistic sediment transport process including bed load and suspended load behaviours at the bottom boundary layer. The model SED-FLUX includes wave module, hydrodynamic module and sediment transport and diffusion module that calculate suspended sediment concentration, net sediment erosion flux($Q_s$) and bed load flux. Bed load transport rate is evaluated by the van Rijn's TRANSPOR program which has been verified in wave-current fields. The net sediment erosion flux($Q_s$) at the bottom is evaluated as a source/sink term in the numerical sediment diffusion model where the suspended sediment concentration becomes a verification parameter of the $Q_s$. Bed level change module calculates a bed level change amount(${\Delta}h_{i,j}$) and updates a bed level. For the model verification the limit depth of the bed load transport is compared with the field experiment data and some formula on the threshold depth for the bed load movement by waves and currents. This model is applied to the beach profile changes by waves, then the model shows a clear erosion and accumulation profile according to the incident wave characteristics. Finally the beach evolution by waves and wave-induced currents behind the offshore breakwater is calculated, where the model shows a tombolo formation in the landward area of the breakwater.