• 물과 미래
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• 제12권2호
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• pp.49-55
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• 1979

본 연구는 관수로내의 부정류 즉 펌푸모터의 시동, 정지 및 발브 조절시에 압력관수로에 나타나는 급변류의 현상, 특히 수격작용의 해석을 Computer에 의해 자동해석하는 방법을 강구하였다. 따라서 사용되는 관수로가 펌푸, 관망, 터널, 조압수조, 분기관, 저수지, 폐단관 및 발브장치를 갖는 일련의 관수로내에 일어나서 전자계산기를 사용하면 송수 또는 배수관로 설계에 있어 설계자의 시간과 노력을 감소하고 정확한 결과를 얻을 수 있는 장점이 있다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -3
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• pp.1451-1454
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• 2002

In recent years, there are growing concerns about land mobile satellite (LMS) communication systems and mobile stratospheric communication systems (SCS) for the purpose of service upgrade of personal and mobile communications in near future. It is important to possess accurate channel model for prediction of the above system performance. Thus, in this paper, we evaluate the bit error rates of a coded BPSK system based on realistic channel model which can be applied to stratospheric communication systems. The channel data was made by fitting the parameters of probability distribution model to measured data. This approach was proposed by Corraza〔1〕and modified by You〔2〕. And also the effects of channel codings on the system performance are analyzed. As results, we can get the performance curve characteristics on realistic Rician log-normal fading channels with various communication environments.

• 태양에너지
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• 제19권4호
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• pp.63-69
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• 1999

The conventional grid connected PV(Photovoltaic) system has a unstable output pattern due to its dependence on the weather condition, although solar-cell array averagely has a regular output characteristics to have a peak output nearly at noon. Therefore assuming the high density grid connection in the future, this unstable output pattern can be one of the main reasons to generate power disturbance such as voltage variation, frequency variation and harmonic voltage generation in low voltage distribution line. However general grid connected solar-cell system do not have functions to cope with these disturbances. Therefore this study proposed a advanced type grid connected PV system with functions to suppress output power fluctuation due to solar-cell array output variation and showed the levelling effect of fluctuation due to instantaneous array output variation.

• 산업공학
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• 제19권4호
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• pp.333-341
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• 2006

RFID (Radio Frequency Identification) is a technology that can input identification information to microchip and make goods, animals, persons recognized, chased, and managed using radio frequency, and is founded on the core technology of ubiquitous environment of the future. In this paper, we propose a RFID integrated system designed to manage the lifecycle of an individual product efficiently. The proposed system can enable traceability and visibility of items through their entire life by integrating distribution and banking information on the basis of EPCglobal Network. It may provide the infra of Digital Manufacturing and RTE (Real Time Enterprise) and effective information sharing structure with existing legacy system (ERP, CRM, SCM) by real time.

• Transactions on Electrical and Electronic Materials
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• 제7권5호
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• pp.217-223
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• 2006

When only partial information is available about equipment failures (installation date and amount, as well as failure and replacement rates), data on sufficiently large number of yearly populations of the components can be combined, and estimation of model parameters may be possible. The parametric models may then be used for forecasting of the system's short term future failure and for formulation of replacement strategies. We employ the Weibull distribution and show how we estimate its parameters from past failure data. Using Monte Carlo simulations, it is possible to assess confidence ranges of the forecasted component performance data.

• 한국정보기술응용학회:학술대회논문집
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• 한국정보기술응용학회 2005년도 6th 2005 International Conference on Computers, Communications and System
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• pp.331-334
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• 2005

This paper suggests the Ethernet aggregation to XGMII framing procedure (EAXFP) mechanism to economically combine the traffic adaptation technology with the link aggregation method in designing 10 Gigabit Ethernet (10 GbE) interfaces. This design sidesteps the data-loss issues that can result from designing an interface with only one link. The most critical issue in relation to the link aggregation interface is the algorithm used to control frame distribution between the ten ports. The proposed EAXFP mechanism offers an efficient link aggregation method as well as an efficient frame distribution algorithm, which maximize the throughout of the 10 GbE interface. In the experiment and analysis of the proposed mechanism, it was also discovered that the 10 GbE interface that uses the proposed EAXFP mechanism significantly reduced the packet loss rate. When there will be heavy traffic loads come about in the future, the proposed EAXFP mechanism assures an efficient and economical transmission performance on the router system.

• 경영과학
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• 제10권2호
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• pp.27-42
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• 1993

Markov chain models can be used to predict the state of the system in the future. We extend the existing Markov chain models in two ways. For the stationary model, we propose a procedure that obtains the transition probabilities by appling the empirical Bayes method, in which the parameters of the prior distribution in the Bayes estimator are obtained on the collaternal micro data. For non-stationary model, we suggest a procedure that obtains a time-varying transition probabilities as a function of the exogenous variables. To illustrate the effectiveness of our extended models, the models are applied to the macro and micro time-series data generated from actual survey. Our stationary model yields reliable parameter values of the prior distribution. And our non-stationary model can predict the variable transition probabilities effectively.

• 유통과학연구
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• 제12권5호
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• pp.93-107
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• 2014

Purpose - The pool of entrepreneurs with progressive qualities such as creativity and innovation was considered concurrently with such factors as work and capital that stimulate economic development and growth. This study aims to present a model to support the development of a strategic approach for achieving an overall academic entrepreneurship system in Iran. Research design, data, and methodology - The research design of this study is based on applied research because of its objectives, using principles and techniques formulated for basic research to solve operational and real organizational issues. This design also drives the method used, describing and interpreting the findings. Secondary data (library research) was used for this study's data collection. Because of this research's essential characteristics, no hypothesis is launched, and no research setting, questionnaire design, population or population sampling, validity or reliability tests, or statistical analysis are needed. Results and Conclusions - The model is created using a strategic approach acting in an octal setting comprising social, cultural, legal, economic, political, technological, competitive, and natural environments to present a conceptual framework for future studies.

• 유통과학연구
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• 제13권10호
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• pp.5-13
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• 2015

Purpose - This study aims to suggest appropriate policies and performance indicators for financial aid recipients. It analyzes the existing regular government policy funds support project, especially its propriety and reasonability. Research design, data, and methodology - When financial aid is effective, it should be able to predict small enterprise business results. Additionally, there should be an evaluation, checking before and after performance rates so that the rate of achievement and outcome can be measured. This study's contribution for small enterprises is in researching the best way to improve this support system. Results - The Small Enterprise and Market Service (SEMAS), currently designated as a support organization for implementing the government financial aid project, has assessment indicators. However, these focus mainly on quantitative indicators and survey results. Conclusions - In the future, there is some need to draw up measures, setting the right direction for developing policies for the small enterprise fund loans and improving the management of the plans. Eventually, this effort will dispel concerns about the present support policy, which is considered to be weakening small enterprises.

• 산업경영시스템학회지
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• 제36권1호
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• pp.36-43
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• 2013

Many retailer store managers are experiencing the situation where some customers balk at purchasing products if the stock is low. In this paper, we extend the single period newsvendor model in an environment of customer balking behavior occurring at double threshold inventory levels assuming the chance of sales during balking is a discrete function of inventory level. Our analysis is based on the assumption that only the mean and the variance of demand are known, without assuming any specific distributional form. We derive the explicit general expression of optimal order quantity with unknown distribution of demand with double threshold inventory levels of customer balking. Then, we illustrate the concepts developed here through simple numerical examples and conclude the future research topics under balking situation.