• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• 제21권4호
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• pp.96-103
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• 2007

In this paper, we present a novel and numerically efficient algorithm for high resolution TOA(Time Of Arrival) estimation under indoor radio propagation channels. The proposed algorithm is not dependent on the structure of receivers, i.e, it can be used with either coherent or non-coherent receivers. The TOA estimation algorithm is based on a high resolution frequency estimation algorithm of Minimum-norm. The efficiency of the proposed algorithm relies on numerical analysis techniques in computing signal or noise subspaces. The algorithm is based on the two step procedures, one for transforming input data to frequency domain data and the other for estimating the unknown TOA using the proposed efficient algorithm. The efficiency in number of operations over other algorithms is presented. The performance of the proposed algorithm is investigated by means of computer simulations.. Throughout the analytic and computer simulation results, we show that the proposed algorithm exhibits superior performance in estimating TOA estimation with limited computational cost.

• The Journal of the Acoustical Society of Korea
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• 제24권3E호
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• pp.109-114
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• 2005

In this paper, we present a phase coherent all-digital transceiver for underwater acoustic communication, which allows the system to reduce complexity and increase robustness in time variant underwater environments. It is designed in the digital domain except for transducers and amplifiers and implemented by using a multiple digital signal processors (DSPs) system. For phase coherent reception, conventional systems employed phase-locked loop (PLL) and delay-locked loop (DLL) for synchronization, but this paper suggests a frame synchronization scheme based on the quadrature receiver structure without using phase information. We show experimental results in the underwater anechoic basin at MOERI. The results show that the adaptive equalizer compensates frame synchronization error and the correction capability is dependent on the length of equalizer.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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• pp.999-1004
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• 2004

In this study, we identify contribution of structure-borne-noise of vehicle HVAC system using Multi-Dimensional spectral analysis (MDSA) method. Firstly, to identify the applicability of MDSA method, the case of HVAC system was modeled with four input / single output system. The four inputs which is given vibration data is composed of blower, evaporator, heater and duct. The single output is noise data from driver's seat. When the blower motor is operating, we analyze the contributions of four input / single output. As a result of experiment, we identify efficiency of systems modeled with four input / single output through ordinary coherence function (OCF) and multiple coherence function (MCF).

• The Journal of the Acoustical Society of Korea
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• 제24권4호
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• pp.230-237
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• 2005

The angle-tracking of maneuvering targets is required to the state estimation and classification of targets in underwater acoustic systems. The Problem of angle-tracking multiple closed and crossing targets has been studied by various authors. Sword et al. Proposed a multiple target an91e-tracking algorithm using angular innovations of the targets during a sampling Period are estimated in the least square sense using the most recent estimate of the sensor output covariance matrix. This algorithm has attractive features of simple structure and avoidance of data association problem. Ryu et al. recently Proposed an effective multiple target angle-tracking algorithm which can obtain the angular innovations of the targets from a signal subspace instead of the sensor output covariance matrix. Hwang et al. improved the computational performance of a multiple target angle-tracking algorithm based on the fact that the steering vector and the noise subspace are orthogonal. These algorithms. however. are ineffective when a subset of the incident sources are coherent. In this Paper, we proposed a new multiple target angle-tracking algorithm for coherent and incoherent sources. The proposed algorithm uses the relationship between source steering vectors and the signal eigenvectors which are multiplied noise covariance matrix. The computer simulation results demonstrate the improved Performance of the Proposed algorithm.

• 한국공간정보시스템학회:학술대회논문집
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• 한국공간정보시스템학회 2004년도 춘계 학술발표회 논문집 제1권1호(통권1호)
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• pp.275-278
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• 2004

This paper focused on problems of design, construction, and maintenance caused by construction implementation processes. They were analyzed through case study of structure safety diagnosis projects. From the case study, it is expected that the introduction of Construction Management from the first stage of procurement will improve construction cost increase or burden on small design company. It strengthens coherent management from design and source contractor selection to build review of responsibility. The coherency will prevent changes in designing or infirm unreliable construction. It is desirable that expert opinions are considered when structure changes and establishment occur and that, if necessary, actions such as source selection, periodic audits, and diagnosis arc checked and fed back to maintenance.

• Sijohaknonchong
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• 제21집
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• pp.5-22
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• 2004

If Sijo poetry is referred to a text which is composed of sentences. its textuality can be explored in terms of 1) the figurative words used in each line. 2) the logical sequence between lines. 3) the syntactic composition of each line. With the ancient Sijo poem. 1) it is composed of logical sentences as a result of extremely restraining from using figurative words that could prevent the reader from grasping the logical sequence within the work; 2) there is a clear cohesion between lines that can make each work perfectly coherent; 3) each line has a balanced syntactic structure, so the entire structure of a Sijo poem is '6 phrases in lines'. With the modem Sijo peom. 1) it abounds in figurative words, which prevent the work from having a logical sequence, and sometimes even from having three lines; 2) there is a loose cohesion between lines which can't make each work coherent; 3) it sometimes destroys the syntactic structure, '6 phrases in 3 lines', unique to traditional Sijo poetry. I think that this trend of modern Sijo poetry can cause haphazard the existence of modern Sijo poetry.

• Journal of the Speleological Society of Korea
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• 제82호
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• pp.13-16
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• 2007

Several research projects funded by National GIS Master Plan have started to produce several outcomes that need to be applied in the real world situation. To make the project results more useful and to improve upon the current results, it is necessary to integrate the project outcomes produced under various circumstances into a consistent and coherent structure.

• Journal of Korean Society of Industrial and Systems Engineering
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• 제21권48호
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• pp.153-164
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• 1998

본 논문은 2-상태 시스템의 신뢰도 계산을 위하여 Heidtmann[3]이 제시한 가역 알고리즘을 부울 대수를 사용하여 경로집합으로부터 절단집합을 유도하거나, 역으로 절단집합으로부터 경로집합을 유도함으로서 효율성을 입증하였으며, 포함-불포함 공식(inclusion-exclusion formula)과 추축 분해법칙(pivotal decomposition rule)을 이용하여 직·병렬구조 및 복합구조의 신뢰도를 계산할 수 있는 알고리즘을 개발, 분석하였다.

• Bulletin of the Korean Chemical Society
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• 제34권3호
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• pp.892-898
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• 2013

A field emission projection microscope was constructed to investigate the atomic and chemical-bonding structure of molecules using electron in-line holography. Fringes of carbon nanotube images were found to be interferograms equivalent to those created by the electron biprism in conventional electron microscopy. By exploiting carbon nanotubes as the filament of the electron biprism, we measured the transverse coherence length of the electron beam from tungsten field emitters. The measurements revealed that a partially coherent electron-beam was emitted from a finite area.

• Journal of Korean Society of Industrial and Systems Engineering
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• 제15권26호
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• pp.85-93
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• 1992

수작업 또는 컴퓨터에 의하여 신뢰도 방정식을 얻을 때 반드시 그것의 옳고 그름을 검정해 볼 필요가 있다. 본 논문에서는 결합구조에 있어서 이항변수를 사용한 이항 성분으로 이항 시스템을 설계하는 법을 제시하였고 검정하기 위하여 검정 방법 두 가지를 신뢰도 방정식의 정확성을 제안하였다. 아울러 몇 가지 예를 들어 계산상의 효과가 배가되었음을 입증하였다.