• Journal of the Korean Data and Information Science Society
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• 제28권1호
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• pp.227-235
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• 2017

When the spatial information of each location is given specifically as coordinates it is popular to use the geographically weighted regression to incorporate the spatial information by assuming that the regression parameters vary spatially across locations. In this paper, we relax the linearity assumption of geographically weighted regression and propose a geographically weighted least squares-support vector machine for estimating geographically weighted mean by using the basic concept of kernel machines. Generalized cross validation function is induced for the model selection. Numerical studies with real datasets have been conducted to compare the performance of proposed method with other methods for predicting geographically weighted mean.

• 대한전자공학회논문지SD
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• 제47권5호
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• pp.10-15
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• 2010

Hadamard code를 이용한 spectral-amplitude-coding optical code-division multiple-access(OCDMA)는 효율적인 시스템을 구성할 수 있으나 $2^n$개의 code length만을 갖는 특성을 지닌다. 이의 한계성을 극복할 수 있는 extended Hadamard codes를 제안하고 주된 잡음인 phase-induced intensity noise(PIIN)를 분석하여 향상된 시스템의 특성을 보인다.

• 대한전자공학회논문지SD
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• 제48권8호
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• pp.5-9
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• 2011

Hadamard code를 이용한 spectral-amplitude-coding optical code-division multiple-access(OCDMA) 시스템은 $2^n$개의 code length만을 갖는 특성을 지니어 최대 사용자 수의 조절이 어렵고 phase-induced intensity noise(PIIN)가 커서 효율적인 시스템 구성이 어렵다. 이의 한계성을 극복할 수 있는 modified Hadamard codes를 제안하고 잡음 분석을 통하여 향상된 시스템 특성을 보인다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2008년도 하계종합학술대회
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• pp.437-438
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• 2008

This paper proposes a 8th-order single loop band-pass sigma-delta modulator that satisfies a wide bandwidth of 6MHz, which is required for a HDTV application. The proposed architecture is based on a simple analog structure that enlarges the noise shaping with a low OSR. In addition, a feedforward scheme is used to relax op-amp performance requirements. The proposed modulator has been simulated using the 0.18um 1.8v TSMC technology. The simulation results show that the bandwidth is 6MHz and SNQR is 70dB.

• 항공우주정책ㆍ법학회지
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• 제9권
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• pp.247-258
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• 1997

Inchon International Airport (IIA) is one of many new airports being constructed in the Asia Pacific region. IIA is located at the center of Northeast Asia connecting 43 major cities within 3.5 hour flight. With the sate-of-the-art airport facilities, IIA will also have the diverse functions of a modern airport for international business, where airport users can work and relax at the same time. It will be built for the multifunction of Pentaport - Airport, Businessport, Teleport, Seaport and Leisureport. IIA will be a leading hub airport for Northeast Asia in the coming 21st century. This paper will focus on the development plan for Inchon International Airport and its current status.

• ETRI Journal
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• 제25권4호
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• pp.270-273
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• 2003

This paper presents a simple process to integrate thin-film inductors with a bottom NiFe magnetic core. NiFe thin films with a thickness of 2 to 3${\mu}m$ were deposited by sputtering. A polyimide buffer layer and shadow mask were used to relax the stress of the NiFe films. The fabricated double spiral thin-film inductor showed an inductance of 0.49${\mu}H$ and a Q factor of 4.8 at 8 MHz. The DC-DC converter with the monolithically integrated thin-film inductor showed comparable performances to those with sandwiched magnetic layers. We simplified the integration process by eliminating the planarization process for the top magnetic core. The efficiency of the DC-DC converter with the monolithic thin-film inductor was 72% when the input voltage and output voltage were 3.5 V and 6 V, respectively, at an operating frequency of 8 MHz.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 2006년도 춘계공동학술대회 논문집
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• pp.1221-1226
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• 2006

The use of Artificial Neural Networks (ANN) has received increasing attention in the analysis and prediction of financial time series. Stationarity of the observed financial time series is the basic underlying assumption in the practical application of ANN on financial time series. In this paper, we will investigate whether it is feasible to relax the stationarity condition to non-stationary time series. Our result discusses the range of complexities caused by non-stationary behavior and finds that overfitting by ANN could be useful in the analysis of such non-stationary complex financial time series.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 2006년도 춘계공동학술대회 논문집
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• pp.25-32
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• 2006

Given a schedule of train to be routed by a Railway Stock, Railway Stock Routing Problem determine a sequence of train while satisfying turnaround time and maintenance restrictions. The objective is to minimize the Railway Stock during a week and each day simultaneously. And we prove that Railway Stock Routing Problem with maintenance restrictions is NP-hard. In this paper, we present two stage approaches that solve the Railway Stock Routing Problem in a reasonable time. In first stage we relax maintenance restrictions and formulate as a Min-cost-flow problem. Then, in the second stage, we attempt to satisfy maintenance restrictions using ours heuristic algorithm. We show the computational result of applying to an actual train schedule data.

• 한국철도학회논문집
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• 제9권4호
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• pp.419-424
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• 2006

In this paper we study on a method to predict and to demonstrate the reliability of the Korea high speed train control system in quantitative point of view. For the prediction of the reliability in train control system which is composed of electronic parts, Relax Software 7.7 automation tool is employed and MIL-HDBK-217 Handbook that is a standard for the prediction of the failure rate in electronic components is used. Mean Time Between Failure (MTBF) is predicted based on the failure rate of the subsystems, State Modeling and Markov Modeling method is used to express a reliability function of the train control system composed by hardware redundancy as a function of time. We propose a Reliability Test which is performed on the level of the subsystems and Failure Report, Analysing, Correction action system which use the test operation data to prove the predicted reliability.

• 제어로봇시스템학회논문지
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• 제4권4호
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• pp.420-426
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• 1998

It is the purpose of this paper to make a preliminary study on the use of repetitive control to improve velocity accuracy by eliminating repetitive disturbances caused by machining inaccuracies of the axis of rotation location. If the control system can be intelligent enough to compensate for such machining errors, then one may be able to improve the accuracy of the velocity control, or alternatively, one may maintain the same accuracy and relax the machining tolerances required. This could decrease cost significantly. Experiments are performed testing repetitive control methods on a constant speed rolling operation testbed. The experimental results show very substantial decreases in the tracking error of the system. Spectral data of the output motion are given to demonstrate the attenuation of the disturbance frequencies and harmonics, related to the bandwidth being used. It is seen that the simplest form of repetitive control which is very easily implemented, can produce striking improvement in control system performance in such belt drive rolling operations, and the learning can be accomplished in a short time.