• The Korean Journal of Applied Statistics
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• v.24 no.6
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• pp.1077-1094
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• 2011

We accomplish clustering analyses for yeast cell cycle microarray expression data. To reflect the characteristics of a time-course data, we screen the genes using the test statistics with Fourier coefficients applying a FDR procedure. We compare the results done by model-based clustering, K-means, PAM, SOM, hierarchical Ward method and Fuzzy method with the yeast data. As the validity measure for clustering results, connectivity, Dunn index and silhouette values are computed and compared. A biological interpretation with GO analysis is also included.

• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.175-178
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• 1999

원형단면을 갖는 수신용 하이드로폰과 같은 면적의 정사각형 단면을 가정하여, 상온의 증류수를 매질로 초음파 변환기에서 방사되는 음장의 공간적 분포를 모의실험하였다. 이러한 "정사각형 평면 근사 평균법(이후 평면 근사 평균법)"을 이용하여, x-축 주사, z-축 주사, xy-평면 주사 및 xz-평면 주사를 모의실험하여 실제 실험에서 나타날 수 있는 여러 가지 현상을 조사하였다. z-축 주사 모의 실험 결과는 Beissner의 이론과 비교하여 비교적 잘 일치하였다

• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.205-209
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• 2017

최근 우리나라의 수자원 관련 기술의 발전과 연구는 상당한 속도로 이루어지고 있다. 그 중 유량측정 분야는 모든 수자원계획과 관리의 근간이 되는 분야로 그 중요성이 상당한 부분을 차지한다. 대부분의 자연하천에서 저평수기는 물의 흐름이 비교적 안정된 정상류 흐름이므로 유속계를 통해 유속분포 및 평균유속의 비교적 정확한 측정이 가능하다. 반면, 홍수기 유량측정은 하천의 수리특성이 급변하고 인력, 장비, 안전 등의 문제로 소극적인 측정을 할 수 밖에 없는 것이 현실이다. 홍수기 유량 측정방법은 부자 측정방법과 전자파 표면유속계와 같은 비접촉식 측정방법에 의존하고 있다. 부자법과 전자파 표면유속계는 평균유속과 유량을 계산하기 위해 측정 유속의 보정계수를 활용하여 평균유속으로 환산하여 사용한다.

• Journal of the Korean Data and Information Science Society
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• v.20 no.6
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• pp.1103-1118
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• 2009

When we wish to estimate the mean or total of a finite population, the numbering of the population units is of importance. In this paper, we have proposed two methods for estimating the mean or total of a population having a linear trend, for the case when the reciprocal of the sampling fraction is an even number and the sample size is an odd number. The first method involves drawing a sample by using a method which is a generalization of Singh et al's (1968) modified systematic sampling, and using interpolation in determining the estimator. The second method involves selecting a sample by modified systematic sampling, and estimating the population parameters by the regression estimation method. Under the criterion of the expected mean square error based on Cochran's (1946) infinite superpopulation model, the proposed methods have been compared with existing methods. We have also made a comparison between the two proposed methods.

• Journal of Korea Water Resources Association
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• v.38 no.10 s.159
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• pp.811-824
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• 2005

The ADCP is an instrument based on Doppler effect, which measures discharge of a river in a short time while crossing it. In this study we aim to make a comparison of the discharge results from a moving-vessel ADCP with those measured by velocity-area method at the same cross-section, and to investigate the characteristics of velocity and discharge data using ADCP. Bathymetry measured by ADCP almost coincides with that by direct depth measurements. Because velocity data from ADCP are essentially instantaneous, individual velocity profiles obtained by ADCP are rather different from time-averaged velocity profiles. But spatially averaged velocity profiles of the individual ADCP data near the comparable verticals have similar vertical velocity pattern with the time-averaged ones. The average velocity profile from repeatedly crossed data is also similar with the time-averaged one. In case of the velocity distribution, individual and spatially averaged data for the sub-width of mid-section method Have good agreement with those by velocity-area method. Discharge data determined by averaging several ADCP measurement transects have $0.1\%{\~}9.3\%$ of difference with those from velocity-area method, and as the number of measurement increases, the relative difference to the velocity-area method decreases.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.05b
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• pp.289-293
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• 2005

본 연구에서는 일별 저수지군 최적연계운영 모형(CoMOM 4.0 : Coordinated Multireservoir Operating Model version 4.0)을 낙동강 수계 실시간 일별 운영에 CoMOM을 적용할 경우를 상정하여, 불확실성을 고려한 실시간 모의 운영을 수행하였다. 실시간 일 운영 시 며칠 정도의 유입량 예측은 가능할 것으로 예상하여 유입량 예측일수의 정확도 증가에 따른 연계 운영 효과를 산정해 본 결과, 전반적으로 과거 실적치에 비하여는 좋지만, 예측일 수가 늘어남에 따라 수계 내 연간 평균 저수량은 감소하는 대신 평균 발전량은 증가하여, 연계운영 총체적 효과가 기하급수적으로 증가됨을 알 수 있었다. 미래 유입량을 전혀 예측하지 못할 경우에는 일평균 유입량을 예측 유입량으로 하여 실시간 댐군 연계모의운영을 하였고, 그 경우에도 여수로 방류로 인한 수계 외 유출을 연 평균 약 214백만$m^3$ 정도 감소시키는 반면, 수계 내 전체 댐 군의 평균저수량을 55백만$m^3$ 증가 시키며, 연간 평균 발전량은 25GWh (약 22.5억원/년의 추가 발전수입) 증가 시킬 수 있을 것으로 분석되었다.

• Journal of Navigation and Port Research
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• v.28 no.6
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• pp.509-515
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• 2004

The aim of this paper is to forecast passenger numbers and freight volumes in 2005 and it is proposed optimal tonnage of passenger ship. The forecasting of passenger numbers and freight volumes is important problem in order to determine optimal tonnage of passenger ship, port plan and development. In this paper, the forecasting of passenger numbers and freight volumes are performed by the method of neural network using back-propagation learning algorithm. And this paper compares the forecasting performance of neural networks with moving average method and exponential smooth method As the result of analysis. The forecasting of passenger numbers and freight volumes is that the neural networks performed better than moving average method and exponential smoothing method on the basis of MSE(mean square error) and MAE(mean absolute error).

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.5
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• pp.1763-1773
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• 1991

본 연구에서는 포화수증기와 공기의 혼합기내에서 분무수적으로의 열 및 질량 전달률을 계산하기 위하여 수적의 부분혼합모형과 비혼합모형에 대하여 수적내 과도온 도분포의 해석해를 적용성이 보장되면서도 계산상의 어려움이 수반되지 않는 형태로 구하기 위하여 수적내부의 열전도해석에 있어서 적분법을 적용하였다. 적분법으로 얻어지는 과도온도분포의 해는 유한차의 다항식으로 표시되어 비혼합모형인 경우 각시 간 구간의 경계에서의 온도분포가 연속성을 유지하면서 물성치들의 온도에 대한 종속 성이 쉽게 고려되고 계산도 용이한 형태이다. 본 보에서 제시하는 해석결과의 적용 성을 조사하기 위하여 완전혼합모형을 포함하는 세가지 수적모형들에 대한 계산결과들 로부터 얻어진 시간변화에 따른 수적의 무차원 체적평균온도변동을 유효한 실험결과들 과 비교, 검토하였으며, 부분혼합모형에 대하여 혼합기의 압력, 수적의 초기온도, 혼 합기 속에 포함되어 있는 수증기의 체적분율, 수적의 초기크기, 수적의 초기속도 및 분사각도가 주위혼합기로부터 수적으로 전달되는 열 및 질량전달에 미치는 영향을 조] 사하고 도출된 대표적인 검토 결과를 제시하였다.

• The Transactions of the Korea Information Processing Society
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• v.7 no.8
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• pp.2565-2574
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• 2000

The error diffusion method is good for reproducing continuous image to binary image. However the reproduction of edge characteristic is weak in power spectrum analysis of display error. In this paper. we present an edge-enhanced error-diffusion method which include pre-processing algorithm for edge characteristic enhancement. Pre-processing algorithm consists of the difference value between current pixel and local average of original image and weighting function of pre-filter. First. it is obtained the difference value between current pixel and the local average of peripheral pixels(5x5) in original image. Second, weighting function of pre-filter is composed by function including absolute value and sign of difference value. The improved Error diffusion algorithm using pre-processing algorithm, present a good result visually which edge characteristic is enhanced. The performance of the proposed algorithm is compared with that of the conventional edge-enhanced error diffusion by measuring the RAPSD of display error, the egde correlation and the local average accordance.

• The Korean Journal of Nuclear Medicine Technology
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• v.18 no.2
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• pp.8-16
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• 2014

Purpose The quantitative analysis of gallbladder emptying is very important in diagnosis of motility disorder of gallbladder and in biliary physiology. The GBEF obtain the statics aquisition method or the dynamic acquisition method in two ways. The purpose of this study is to compare the GBEF value of statics acquisition method and the dynamic acquisition method. And we find the best way for calculate GBEF. Materials and Methods The quantitative hepatobiliary scan with $^{99m}Tc$-mebrofenin was performed of 27 patients. Initial images were acquired statically, for 60 min after injection of the radioactive tracer. And if the gallbladder is visualized to 60 min, performed stimulation of gallbladder (1egg, 200 mL milk). After that, started acquisition of dynamic image for 30 min. After that, image of after fatty meal of the statics method were acquired on equal terms with 60 min image. The statics GBEF was calculated using the images of before fatty meal and post fatty meal by the statics method. The dynamic GBEF was calculated using the images of time of maximum bile juice uptake ($T_{max}$) and time of minimum bile juice uptake ($T_{min}$) images from the gallbladder time-activity curve. A bile juice is secreted from gallbladder while eating a fatty meal. that is named early GBEF and that was calculated using before fatty meal image of the statics method and 1 min image of the dynamic method. Results The result saw very big difference between two according to $T_{max}$. The result, were as follows. 1) In case of less than 1 min, the dynamic mean GBEF was $40.1{\pm}21.7%$, the statics mean GBEF was $51.5{\pm}23.6%$ in 16 cases. The early mean GBEF was $14.0{\pm}29.1%$. The GBEF of statics method was higher because that include secreted bile juice while performed stimulation of gallbladder. A difference of GB counts according to acquisition method and the early bile juice counts was $17.6{\pm}14.8%$ and $13.5{\pm}15.3%$. 2) In case of exceed than 1 min, the dynamic mean GBEF was $31.0{\pm}19.7%$, the statics mean GBEF was $21.3{\pm}19.4%$ in 7 cases. The early GBEF was $-6.9{\pm}4.9%$. The GBEF of dynamic method was higher because that include concentrated bile juice to $T_{max}$. A difference of GB counts according to acquisition method and the early bile juice counts was $14.3{\pm}7.3%$ and $5.9{\pm}3.9%$. Conclusion The statics method is very easy and simple, but in case of $T_{max}$ delay, the GBEF can be lower. The dynamic method is able to calculate accurately in case of $T_{max}$ delay, but in case of $T_{max}$ is less than 1 min, the GBEF can be lower because dynamic GBEF exclude secreted bile juice while performed stimulation of gallbladder. The best way to calculate GBEF is to scan with dynamic method preferentially and to choose suitable method between the two way after conform $T_{max}$ on the T-A curve of the dynamic method.