• Journal of Hydrogen and New Energy
• /
• v.14 no.1
• /
• pp.61-68
• /
• 2003

This paper presents the methodology to analyze flow duration characteristics and performance prediction technique for small hydro power(SHP) Plants and its application. The flow duration curve can be decided by using monthly rainfall data at the most of the SHP sites with no useful hydrological data. It was proved that the monthly rainfall data can be characterized by using the cumulative density function of Weibull distribution and Thiessen method were adopted to decide flow duration curve at SHP plants. And, the performance prediction technique has been studied and development. One SHP plant was selected and performance characteristics was analyzed by using the developed technique, Primary design specfications such as design flowrate, plant capacity, operational rate and annual electricity production for the SHP plant were estimated, It was found that the methodology developed in this study can be a useful tool to predict the performance of SHP plants and candidate sites in Korea.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.14 no.5
• /
• pp.1159-1166
• /
• 1994

This study presents the methodology for the performance analysis and prediction of small hydro power plants(SHP). Rainfall data are characterized to estimate the flow duration curve of SHP, using the cumulative density function of Weibull distribution. The model for the performance analysis of SHP is developed. Also, the performance characteristics of the existing Anheung Plant located in Han River basin are analyzed by using the developed model. As a result, it was found that the model is suitable to analyze the performance characteristics of existing SHP and to predict the primary design performance such as the design flowrate, capacity, rate of operation and annual electricity production of SHP.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.14 no.3
• /
• pp.89-97
• /
• 2014

In this paper, we propose real-time program that measure open-close frequency of mouth and eyes to detect drowsiness of a driver. This program detects a face to the CCD camera image using OpenCV library. Then that extracts each area using CDF for eye detection and Active Contour for mouth detection based on detected face. This system measures each frequency of Open-Close using extracted area data of eyes and mouth. We propose foundation technique how to perform sleepiness decision of users based on measurement data.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.38B no.4
• /
• pp.240-246
• /
• 2013

In heterogeneous networks, the almost blank subframes (ABS) for inter-cell interference coordination (ICIC), which can be protected from the CCI due to unutilized subframes (i.e., ABS) is proposed. However, the analytical model for ABS-based systems has not been fully studied yet. In this paper, we derive a new analytical model to evaluate the performance of ABS-based systems. In an analytic model, we assume that each carrier in multicarrier systems, such as in OFDMA, is subject to large-scale fading, which is independent of other carriers. As a performance measure, we present the cumulative distribution function (CDF) for the effective SINR. We show the accuracy of the analytical model via simulation results.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.41 no.11
• /
• pp.1099-1108
• /
• 2017

Data points obtained by conducting repetitive experiments under identical environmental conditions are, theoretically, required to correspond. However, experimental data often display variations due to generated errors or noise resulting from various factors and inherent uncertainties. In this study, an algorithm aiming to determine valid bounds of input variables, representing uncertainties, was developed using probabilistic and statistical methods. Furthermore, a reliability assessment was performed to verify and validate applications of this algorithm using bolt-fastening friction coefficient data in a sample application.

• Water for future
• /
• v.24 no.1
• /
• pp.63-71
• /
• 1991

This study represents the methodology for feasibility analysis of small hydro power plants. Cumulative density function of Weibull distribution and Thi-essen method were adopted to beside flow duration curve at candidate sites. The performance prediction model and construction cost estimation model for tunnel-type small hydro power plants were developed. Eight candidate sites existing on Han river selected and surveyed for actual sites reconnaissance. The performance characteristics and economical feasibility for these sites were analyzed by using developed models. As a result, it was found that the optimum design flowrates with the lowest unit generation cost for tunnel-type small hydro power plants were the flowrate concerning with between 20 % and 30 % of time ratio on the flow duration curve. Additionally, primary design specifications such as design flowrate, effective head, capacity, annual average load factor, annual electricity production were estimated and discussed for surveyed sites.

• Proceedings of the Korean Society of Broadcast Engineers Conference
• /
• 2011.11a
• /
• pp.349-352
• /
• 2011

모바일 IPTV는 이동통신망을 이용하여 방송서비스를 제공한다. 이동통신망을 통해 원활하게 방송서비스를 제공하기 위해서는 극복해야 할 기술적인 장벽이 몇 가지 존재한다. 그 중 하나로, 사용자가 기지국과 기지국 사이를 이동하는 경우 통신망은 연속적으로 서비스를 제공하기 위해 상대 기지국에 사용자의 정보를 전달하는 핸드오버 절차가 수행된다. 핸드오버 절차가 수행되면 시간의 지연이 발생하는데, 시간 지연은 방송 품질에 영향을 미칠 수 있다. 따라서 핸드오버의 발생에 따른 성능 분석은 원활한 방송 서비스를 제공하는데 있어 필수적인 과정으로 볼 수 있다. 본 논문은 핸드오버 성능을 분석하기 위하여 기본적인 무선 액세스 네트워크의 기능이 이미 구현되어 있는 NLS(Network-level Simulator)를 이용한 모의실험 방법을 제시한다. 하지만, 성능 분석에 필요한 기능이 모두 NLS에 포함되어 있지는 않다. 따라서 본 논문에서는 NLS 중 하나인 QualNet을 이용하여 핸드오버 성능 분석에 필요한 기능을 구현하는 방법을 예로 설명한다. 성능은 핸드오버 지연시간과 지연시간의 CDF(Cumulative Distribution Function) 로서 나타낸다.

• Journal of The Korean Astronomical Society
• /
• v.27 no.2
• /
• pp.103-117
• /
• 1994

To extend the work of Gott, Park, and Lee (1989), statistical properties of gravitational lensing in a wide variety of cosmological models involving non-zero cosmological constant is investigated, using the redshifts of both lens and source and observed angular separation of images for gravitational lens systems. We assume singular isothermal sphere as lensing galaxy in homogenous and isotropic Friedmann­Lemaitre-Robertson- Walker universe, Schechter luminosity function, standard angular diameter distance formula and other galaxy parameters used in Fukugita and Turner (1991). To find the most adequate flat cosmological model and put a limit on the value of dimensionless cosmological constant $\lambda_0$, the mean value of the angular separation of images, probability distribution of angular separation and cumulative probability are calculated for given source and lens redshifts and compared with the observed values through several statistical methods. When there is no angular selection effect, models with highest value of $\lambda_0$ is preferred generally. When the angular selection effects are considered, the preferred model depends on the shape of the selection functions and statistical methods; yet, models with large $\lambda_0$ are preferred in general. However, the present data can not rule out any of the flat universe models with enough confidence. This approach can potentially select out best model. But at the moment, we need more data.

• Journal of Communications and Networks
• /
• v.13 no.4
• /
• pp.319-326
• /
• 2011

Beamforming techniques have been successfully utilized for traffic channels in order to solve the interference problem. However, their use for control channels has not been sufficiently investigated. In this paper, a (semi-) centralized beamforming strategy that adaptively changes beam patterns and controls the total transmit power of cells is proposed for the performance enhancement of the common channel in hierarchical cell structure (HCS) networks. In addition, some examples of its practical implementation with low complexity are presented for two-tier HCS networks consisting of macro and pico cells. The performance of the proposed scheme has been evaluated through multi-cell system-level simulations under optimistic and pessimistic interference scenarios. The cumulative distribution function of user geometry or channel quality has been used as a performance metric since in the case of common control channel the number of outage users is more important than the sum rate. Simulation results confirm that the proposed scheme provides a significant gain compared to the random beamforming scheme as well as conventional systems that do not use the proposed algorithm. Finally, the proposed scheme can be applied simultaneously to several adjacent macro and pico cells even if it is designed primarily for the pico cell within macro cells.

• IE interfaces
• /
• v.7 no.3
• /
• pp.201-212
• /
• 1994

In this paper, we develop computerized procedures of the S-Curve, the cumulative progress rates of load input, applied to shipbuilding basic plan. For a real world ship yard, we study the application related problems and develop more efficient procedures of applying the curves in terms of usability and computerization. The yard currently do not have any mathematical expression for the S-Curve. They express the curves using data tables which represents data points of the manually drafted S-Curve graphs, which causes the difficulties in efficient computerization. Another problem the yard has is the lack of the feedback procedure of the actual load different from the initial plan. Due to those problems, the application procedures of the S-Curve require much time and endeavor amounting two full time employees. To resolve the problems, we develop the mathematical expression of the S-Curve using beta distribution function and the feedback procedure regenerating the planned load reflecting the difference between the initial plan and its realization. To build user friendly program, the graphic user interface is also developed using OSF/MOTIF toolkits. Through the development, we reduce the burden required in applying the curves to a part-time job of one employee.