• Journal of Ocean Engineering and Technology
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• v.14 no.1
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• pp.1-5
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• 2000

A numerical analysis for wave motion in the shallow water is presented. The method is based on potential theory. The fully nonlinear free surface boundary condition is assumed in an inner domain and this solution is matched along an assumed common boundary to a linear solution in outer domain. In two-dimensional problem Cauchy's integral theorem is applied to calculate the complex potential and its time derivative along boundary.

• Proceedings of the Korean Magnestics Society Conference
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• 2002.12a
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• pp.132-133
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• 2002

자속밀도를 측정하기 위한 방법으로 Hall 효과; NMR, Fluxgate 등의 다양한 방법등을 사용하고 있다. 그러나 가장 많이 사용되는 방법이 Faraday 전자기 유도 법칙을 이용하여 자속밀도를 측정하는 방법이다. 이 경우 탐지코일에 유도되는 기전력이 자속의 시간 변화율에 비례하기 때문에 자속을 측정하기 위해서는 탐지코일에 유도되는 기전력을 적분을 하여야 한다. (중략)

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 1998.10a
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• pp.166-172
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• 1998

PD 제어기는 산업현장에 가장 널리 운영되는 제어알고리즘이지만 지금까지 보편적으로 사용되고 있는 PID 파라메터 동조방법인 Ziegler-Nichols 동조법으로는 화학공정 같은 비선형 특성이 크거나, 시정수가 큰 플래트에서는 좋은 성능을 얻을 수 없다. 본 논문에서는 릴레이 동조 실험을 통하여 임계 이득과 발진주기를 구하고, 이 값들로부터 Z-N 동조법을 적용하여 초기 동조값을 구한다. 이 값에 의해서 얻어진 공정 출력의 오차와 오차변화율을 입력으로 한 퍼지 동조기를 통하여 PID 제어기의 비례이득과 적분시간을 구하는 동조 방법을 제시한다.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.144.2-144.2
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• 2012

접촉 식쌍성 FZ Ori를 CCD 측광 관측하여 BVRI 광도곡선을 얻고, 12개의 새로운 극심시각을 결정하였다. 먼저 우리가 구한 극심시각들을 포함한 총 218개의 극심시각 자료를 이용하여 FZ Ori의 공전주기 변화를 분석하였다. 그 결과 지난 80년 동안 FZ Ori의 공전주기가 영년 증가하면서 동시에 40~50년 주기로 변화하고 있음을 발견하였다. 우리는 주기적 변화가 제3천체에 의한 광시간 효과로 나타난다고 가정하고 몬테카를로 기법을 이용하여 $X^2_r$인 자 공간에서 최적의 광시간 해를 탐색하였다. 또 이 방법으로 구한 광시간 궤도요소를 궤도 수치적분 프로그램(MERCURY, S34BODY)에 적용하여 질점으로 이루어진 가상의 삼중성계에서 나타나는 광시간 효과를 천체역학적으로 구현하여 보았다. 한편 FZ Ori의 4색 광도곡선을 가장 최근에 개정된 2010 Wilson-Devinney 프로그램에 적용하여 측광학적 해를 구하였다. 기본 시스템 인자 외에 차가운 흑점과 뜨거운 흑점, 그리고 제3광도의 세 요인들을 조합하여 구한 14개의 해 중에서 주성과 반성의 표면에 각각 차가운 흑점과 뜨거운 흑점이 있으면서 제3광도가 검출된 해가 우리의 관측과 가장 잘 맞았다. 그러나 이렇게 구한 제3광도는 광시간 모형으로부터 예측되는 제3천체의 광도에 크게 못 미친다. 추후 분광 관측을 비롯한 다양한 방법을 동원한다면 FZ Ori에 대한 보다 완전한 모형을 얻을 수 있을 것이다.

• Journal of Korean Society of Transportation
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• v.20 no.1
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• pp.65-76
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• 2002

This study is realized using fuzzy evaluation and AHP(the analytic hierarchy process) for the optimum search of traffic route and estimated by the quantitative analysis in the vague subjective judgement. It is different from classical route search and noticed thinking method of human. Appraisal element, weight, appraisal value of route is extracted from basic of the opinion gathering fur the driving expert and example of route model was used for the finding of practice utility. Model assessment was performed attribute membership function making of estimate element, estimate value setting, weight define by the AHP, non additive presentation of weight according to $\lambda$-fuzzy measure, Choquet fuzzy integral.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.11
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• pp.1619-1626
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• 2021

Unlike traditional delta-sigma analog-to-digital converters, incremental analog-to-digital converters enable 1:1 mapping of input and output through a reset operation, which can be used very easily for multiplexing. Incremental analog-to-digital converters also allow for simpler digital filter designs compared to traditional delta-sigma converters. Therefore, starting with analysis in the time domain of the delayed integrator and non-delayed integrator, which are the basic blocks of analog-to-digital converter design, the design equations of a second-order input feed-forward, extended counting, 2+1 MASH (Multi-stAge-noise-SHaping), 2+2 MASH incremental analog-to-digital converter are derived in this paper. This allows not only prediction of the performance of the incremental analog-to-digital converter before design, but also the design of a digital filter suitable for each analog-to-digital converter. In addition, extended counting and MASH design techniques were proposed to improve the accuracy of analog-to-digital converters.

• Korean Journal of Applied Biomechanics
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• v.19 no.2
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• pp.227-235
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• 2009

The purpose of this study was to analyze differences of 45minutes up-hill walking depending on hiking poles and steady walking time. Seven healthy men volunteered for this experiment. Each of them performed up-hill walking with hiking poles and without hiking poles at speed of 3.5km/h during 45minutes on a treadmill. The treadmill was set 25% up-hill inclination. The lower extremity 4 muscles activity including rectus femoris, tibialis anterior, gastrocnemius, biceps femoris was recorded and assessed by using EMG. And Heart rate(HR) and Rating of perceived exertion(RPE) were recorded and analyzed by 15minutes interval. The statistical analysis was two-way ANOVA with repeated measures to compare effects of hiking poles and steady walking time. The level of statistical significance for all tests was P<.05. The results of this study were following : Integrated EMG about four individual muscles doesn't have statistical significancy. However, the sum of IEMG of the four muscles was decreased some with poles than without poles(p<.0l) and IEMG about four muscles was rut different on steady walking time. Second, HR was increased significantly as time up(P<.01). RPE was decreased some with poles than without poles(P<.05) and RPE was increased significantly as time up(P<.01).

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.3 no.4
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• pp.223-234
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• 1991

In this paper, the harbor tranquility problem is analysed by an improved boundary integral equation method. The effect of the diffracted wave transformation induced by the breakwater and structures located at a harbor mouth is considered. Partial reflection concept is also used to consider energy dissipation effects. The present model is verified by comparing the results of the model for rectangular and semi-circular harbors with the analytic solutions. they show a reasonable agreement. Also the wave height distribution of the HUPO harbor computed using the present model agree well to those from the previous hydraulic model tests. It also shows a good agreement with the results from the time-dependent mild slope equation model.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.9
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• pp.107-114
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• 2004

This paper presents block and timing diagrams of the DWA(Data Weighted Averaging) to optimize a feedback time delay of the sigma-delta modulator. Through the MATLAB modeling, the optimized coefficients of the integrators are obtained to design the modulator. The fully differential SC integrators, feedback DAC, 9-level quantizer, and DWA are designed by considering the nonideal characteristics of the modulator. The designed third-order multibit modulator is fabricated in a 0.35${\mu}{\textrm}{m}$ CMOS process. The modulator achieves 75dB signal-to-noise ratio and 74dB dynamic range at 1.2Vp-p 825kHz input signal and 52.8MHE sampling frequency.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.9 s.112
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• pp.895-899
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• 2006

A compact representation of Green function is proposed by applying the discrete wavelet concept in the k-domain, which can be used for the acceleration of scattered field calculations in integral equation methods. Since the representation of Green function is very compact in the joint spatio-spectral domain, it can be effectively utilized in the fast computation of radiation integral of electromagnetic problems. A mathematical expression of Green function based on the discrete wavelet concept is derived and its characteristics are discussed.