• 대한전기학회논문지:전력기술부문A
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• 제48권10호
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• pp.1198-1205
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• 1999

This study is focused on the reliability evaluation for distribution system based on deterministic evaluation technique. Average failure rates, average outage time, and average annual outage time of electrical parts and load points are calculated through network reduction method and failure mode & effective analysis method. And reliability indices of distribution system are calculated. Finally, by employing analytic hierarchy process method, unique index which evaluates and improves the distribution system is calculated. As a result, finding weak points and expansion schedule of the system is possible. The usefulness of this method is verified by applying it to the Inchon International Airport.

• 한국환경과학회지
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• 제9권1호
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• pp.13-18
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• 2000

The purpose of this study is to estimate the low-flow statistics at the mountainous watershed. The formulation for the estimation of the design low-flow statistics was obtained by means of a hydraulic approach applied to a simple conceptual model for a mountainous watershed. Three of the independent variables associated with the low-flow statistics is watershed area(A), average basin slope(S) and the base flow recession constant(K); Watershed area was measured from topographic maps and average basin slope is approximated in this study using Strahler's slope determining method. And base flow recession constant computed using Vogel and Kroll's method. Unfortunately, this method is usually unavailable at ungaged sites. In this study, recession constant at ungaged sites is estimated using graphical regression method used by Giese and Mason. The model for estimating low-flow statistics were applied to all 61 catchments in the Sumjin, Mankyung basin.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2004년도 ICEIC The International Conference on Electronics Informations and Communications
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• pp.447-450
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• 2004

This paper proposes remotely sensed image classification method by fuzzy c-means clustering algorithm using average intra-cluster distance. The average intra-cluster distance acquires an average of the vector set belong to each cluster and proportionates to its size and density. We perform classification according to pixel's membership grade by cluster center of fuzzy c-means clustering using the mean-values of training data about each class. Fuzzy c-means algorithm considered membership degree for inter-cluster of each class. And then, we validate degree of overlap between clusters. A pixel which has a high degree of overlap applies to the maximum likelihood classification method. Finally, we decide category by comparing with fuzzy membership degree and likelihood rate. The proposed method is applied to IKONOS remote sensing satellite image for the verifying test.

• 풍력에너지저널
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• 제10권3호
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• pp.5-11
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• 2019

This paper suggests and compares two algorithms, a moving average filter method and a method developed by the National Renewable Energy Laboratory (NREL), to verify the yaw control algorithm characteristic to reduce yaw error for a wind turbine. A characteristic change for yaw movement in accordance with control parameter change that consists of each control method has been verified. Also, yaw simulations were performed using nacelle wind data measured from two areas with different turbulence intensities and the yaw movement data in each area was compared. These two algorithms and real data were compared by calculating mean absolute error (MSE) and the number of yawing (NY). As a result of the analysis, the MSE values were not significantly different between the two algorithms, but the algorithm proposed by the NREL was found to reduce yaw movement by up to 50 percent more than the moving average filter method.

• 한국기후변화학회지
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• 제9권1호
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• pp.47-58
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• 2018

In this study, we evaluated the uncertainty in the process of selecting GCM and downscaling method for assessing the impact of climate change, and influence of user-centered climate change information on reproducibility of Chungju Dam inflow was analyzed. First, we selected the top 16 GCMs through the evaluation of spatio-temporal reproducibility of 29 raw GCMs using 30-year average of 10-day precipitation without any bias-correction. The climate extreme indices including annual total precipitation and annual maximum 1-day precipitation were selected as the relevant indices to the dam inflow. The Simple Quantile Mapping (SQM) downscaling method was selected through the evaluation of reproducibility of selected indices and spatial correlation among weather stations. SWAT simulation results for the past 30 years period by considering limitations in weather input showed the satisfactory results with monthly model efficiency of 0.92. The error in average dam inflow according to selection of GCMs and downscaling method showed the bests result when 16 GCMs selected raw GCM analysi were used. It was found that selection of downscaling method rather than selection of GCM is more is important in overall uncertainties. The average inflow for the future period increased in all RCP scenarios as time goes on from near-future to far-future periods. Also, it was predicted that the inflow volume will be higher in the RCP 8.5 scenario than in the RCP 4.5 scenario in all future periods. Maximum daily inflow, which is important for flood control, showed a high changing rate more than twice as much as the average inflow amount. It is also important to understand the seasonal fluctuation of the inflow for the dam management purpose. Both average inflow and maximum inflow showed a tendency to increase mainly in July and August during near-future period while average and maximum inflows increased through the whole period of months in both mid-future and far-future periods.

• 대한화학회지
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• 제51권2호
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• pp.125-128
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• 2007

Numerov-Cooley 방법을 적용할 때 양쪽에서 전파된 파동함수를 연결시키는 것이 관건인데, 잘 알려진 스프레드시트인 엑셀에서 해찾기 도구를 활용하여 Numerov 방법의 파동함수 연결을 해결하였다. 한쪽방향으로 전파하여 얻은 에너지 값과 반대쪽으로 전파하여 얻은 에너지 값들의 평균을 이용해 상태함수의 고유값을 정하는 방법도 같은 결과를 보임을 확인하였다. 산화질소 분자 퍼텐셜 위에서 이 방법을 적용하였고, 진동에너지에 따른 원자간 평균거리와 터널링 변화를 계산하였다. 진동에너지가 증가하면서 분자 결합 길이는 비례하여 늘어나지만, 터널 효과는 모든 진동 상태가 어느 정도의 확률을 가지며 에너지 증가에 둔감하다는 것을 확인하였다.

• 상하수도학회지
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• 제28권1호
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• pp.33-45
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• 2014

In this study, current sewer infiltration/Inflow(I/I) computation and application method was examined about improvement and adequacy relating to the main issues raised by the field for practitioners. The results of review about infiltration calculation method were considered to be in need of improvement at 'standards of minimum sewage calculation'. Furthermore, the results of review about I/I application method were considered to be in need of improvement at 'standards of seasonal infiltration application' and 'the relative decrease in the Annual evaluation standards'. In addition, annual I/I analysis at JC County for the four years(2009~2012) in respect of operation flow and rainfall data was conducted. The result of annual infiltration analysis, compared average daily sewage generated average infiltration rate was found in 21.95 %, infiltration by unit was found in $0.31m^3/day/cm/km$ and $0.12m^3/day/day$, respectively. The result of annual inflow analysis, average rainfall - Inflow equations was found $y=5.499{\times}$($R^2$ 0.793), and the average Inflow quantity by sewer extension was predicted to $0.66m^3/mm-km$.

• Journal of the Korean Data and Information Science Society
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• 제25권2호
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• pp.411-422
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• 2014

본 연구는 2011학년도 입학하여 여섯 학기 연속 이수한 학생을 대상으로 평균 GPA의 초기값(intercept), 기울기 (slope), 2차항 (quadratic term)을 구하여 이수학기가 늘어나면서 평균 GPA가 어떻게 변화하는지 분석하였다. 구체적으로 이수학기가 늘어나면서 성별과 모집단위에 따라 평균 GPA의 초기값, 기울기, 2차항에 차이가 있는지 분석하였다. 그 결과 초기값에 영향을 주는 변수는 모집단위, 기울기에 영향을 주는 변수는 성별이며 2차항에 영향을 미치는 변수는 하나도 없었다.

• ETRI Journal
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• 제26권5호
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• pp.375-383
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• 2004

This paper proposes a common interleaving method associated with independent channel-encoding among transmitter antenna branches in orthogonal frequency and code division multiplexing based on multiple-input multiple-output (MIMO) multiplexing to achieve an extremely high throughput such as 1 Gbps using a 100 MHz bandwidth. This paper also investigates the average packet error rate performance as a function of the average received signal energy per bit-to-background noise power spectrum density ratio $(E_b/N_0)$. We found that the loss in the required average received $E_b/N_0$ of the proposed method is only within approximately 0.3 dB in up to a 12-path Rayleigh fading channel, using 16QAM and Turbo coding with a coding rate of 5/6. We also clarify that even for a large fading correlation among antenna branches, 1 Gbps is still possible by increasing the transmission power. Therefore, the proposed method reduces the processing rate to 1/4 in the turbo decoder with only a slight loss in the required average received $E_b/N_0$.

• 대한조선학회논문집
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• 제50권4호
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• pp.255-261
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• 2013

This paper presents prediction of ultimate longitudinal strength of a VLCC, "Energy Concentration" for which many benchmark studies have been carried out, based on kinematic displacement method proposed by Tayyar and Bayraktarkatal (2012). Kinematic displacement theory provides semi-analytical solution of average compressive strengths for various kinds of stiffened panels. The accuracy of average compressive strengths obtained from formulas of CSR(common structural rules) for tankers and kinematic displacement method are discussed in the fore part of this paper. Hull girder ultimate strengths using Smith method are also compared for different average compressive strengths. By comparing them with other benchmark results, it is concluded that the new method provides lower bounds, because hull girder strengths under the sagging and hogging moment conditions approach nearly lower bounds.