• 한국의학물리학회:학술대회논문집
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• 한국의학물리학회 2002년도 Proceedings
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• pp.302-304
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• 2002

In linac-based stereotactic radiosurgery, assuring the quality of the planning and delivery of external photon beam requires accurate evaluation of beam parameters, usually including output factors, tissue-phantom ratio and off-axis ratios, and measurement of actual dose distributions from simulated treatment. We're going to test the use of calibrated radio chromic film (Gafchromic film; type MD-55, Nuclear associate) using a Lumiscan 75 digitizer to measure absolute dose and relative dose distributions for linac-based radiosurgery unit Relative dose distribution of a human-style spherical acryl phantom were measured using radiochromic film and calculated by treatment planning system. The absolute dose at the sphere center was measured by radiochromic film and micro chamber (Exradin A-14, 0.009cc). What we want to demonstrate in this work, the 'well selected' radiochromic films when external photon beam are used in linac-based stereotactic radiosurgery are very accurate detector for dosimetry.

• Journal of Communications and Networks
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• 제13권2호
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• pp.149-159
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• 2011

In this paper, we study the problem of how to design a medical-grade wireless local area network (WLAN) for healthcare facilities. First, unlike the IEEE 802.11e MAC, which categorizes traffic primarily by their delay constraints, we prioritize medical applications according to their medical urgency. Second, we propose a mechanism that can guarantee absolute priority to each traffic category, which is critical for medical-grade quality of service (QoS), while the conventional 802.11e MAC only provides relative priority to each traffic category. Based on absolute priority, we focus on the performance of real-time patient monitoring applications, and derive the optimal contention window size that can significantly improve the throughput performance. Finally, for proper performance evaluation from a medical viewpoint, we introduce the weighted diagnostic distortion (WDD) as a medical QoS metric to effectively measure the medical diagnosability by extracting the main diagnostic features of medical signal. Our simulation result shows that the proposed mechanism, together with medical categorization using absolute priority, can significantly improve the medical-grade QoS performance over the conventional IEEE 802.11e MAC.

• 한국농림기상학회지
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• 제14권4호
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• pp.269-276
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• 2012

작물모형 평가에 사용되거나 사용할 수 있는 9가지 지표를 소개하였으며 이들의 특징은 다음과 같다. efficiency of model (EF)와 index of agreement (d)은 dimension이 없고 관측수(n)에 의존적이지 않았으며, dimension에 대해서만 자유로운 것은 relative root mean square error (RRMSE), bias factor (Bf)와 accuracy factor (Af)이다. Root mean sqruar, mean error, mean absolute error들은 관측수와 dimension에 영향을 받기 때문에 판단 시 주의가 필요하다. 따라서 이들의 특징을 파악하여 목적에 맞게 모형의 성능을 파악하여야 한다.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회/대한산업공학회 2003년도 춘계공동학술대회
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• pp.966-971
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• 2003

[ $\lceil\;Cost Effectiveness Analysis\;\rfloor$ ] has been widely used to evaluate effectiveness of R&D resources. But, almost of cost effectiveness evaluation systems have some problems, especially estimating method of effect on R&D project is very rough and imprecise. To solve this problem, we have designed new single effect evaluation system, which are able to apply the distribution of order statistics and to transform relative measure into absolute measure for getting single effect.

• 한국의류산업학회지
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• 제9권1호
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• pp.81-88
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• 2007

This study aimed to develop priorities alternatives based on relative rather than absolute assignments on clothing evaluative criteria. The relative comparison approach includes much redundancy and is thus less sensitive to judgemental errors common to techniques using absolute assignments. By deriving evaluative criteria for consumers in choosing clothing, and considering their relative important or value in the priority of evaluation elements. When the consumer selects clothing, it requires multi-criteria decision making exercise and needs to make trade-offs between different alternatives. With an application of the AHP's hierarchical structuring and pair-wise comparisons, this study will determine the weight and priorities of evaluation factor in clothing evaluative criteria in choosing cloth, which will eventually lead to improve management. Items for the setting priority were decided as 'symbol', 'practicality', 'economy', 'vogue', and 'aesthetic' by council. The data for this research were collected from respondents of 108 females in Busan. Data were analyzed by frequency and AHP. As the results, 'economy' was decided as a most important item. And 'a fashionable color' evaluated as that of first priority in the totality evaluation elements.

• 한국정보통신학회논문지
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• 제17권5호
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• pp.1233-1238
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• 2013

대부분의 대학에서 실시되고 있는 강의평가는 교과목의 특성에 따라 많은 차이가 있음에도 불구하고 강의평가의 절대점수를 활용하여 교수평가를 하고 있다. 강의평가의 신뢰성 확보는 교육의 질 향상을 위해 학생들의 의견을 교수에게 피드백한다는 점에서 매우 중요하다. 본 논문에서는 신뢰성 있는 강의평가 결과를 얻기 위해 고려해야할 여러 요소 가운데 학생들의 출석률과 강의평가의 관계를 살펴보고자 한다.

• 산업경영시스템학회지
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• 제38권3호
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• pp.159-168
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• 2015

Aggregate Production Planning determines levels of production, human resources, inventory to maximize company's profits and fulfill customer's demands based on demand forecasts. Since performance of aggregate production planning heavily depends on accuracy of given forecasting demands, choosing an accurate forecasting method should be antecedent for achieving a good aggregate production planning. Generally, typical forecasting error metrics such as MSE (Mean Squared Error), MAD (Mean Absolute Deviation), MAPE (Mean Absolute Percentage Error), and CFE (Cumulated Forecast Error) are utilized to choose a proper forecasting method for an aggregate production planning. However, these metrics are designed only to measure a difference between real and forecast demands and they are not able to consider any results such as increasing cost or decreasing profit caused by forecasting error. Consequently, the traditional metrics fail to give enough explanation to select a good forecasting method in aggregate production planning. To overcome this limitation of typical metrics for forecasting method this study suggests a new metric, WACFE (Weighted Absolute and Cumulative Forecast Error), to evaluate forecasting methods. Basically, the WACFE is designed to consider not only forecasting errors but also costs which the errors might cause in for Aggregate Production Planning. The WACFE is a product sum of cumulative forecasting error and weight factors for backorder and inventory costs. We demonstrate the effectiveness of the proposed metric by conducting intensive experiments with demand data sets from M3-competition. Finally, we showed that the WACFE provides a higher correlation with the total cost than other metrics and, consequently, is a better performance in selection of forecasting methods for aggregate production planning.

• 웰빙융합연구
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• 제6권3호
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• pp.13-18
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• 2023

Purpose: The small-scale environmental impact assessment has been in operation since its implementation in August 2000, and is a system that meets the purpose of sustainable development in consideration of the environment in areas requiring conservation. However, when preparing a small environmental impact assessment report, the contents of the reduction measures are too qualitative, or reports are prepared to simply list the compliance stipulated by individual laws, and the contents of consultations prepared by consultative agencies and review agencies are not much different. In addition, the direction of consultation on development projects for similar locations of the same project type is frequently changed by reflecting the subjective judgment of the consultative officer of the Ministry of Environment (Environment Agency). Therefore, this study attempted to improve the establishment of measures to reduce the existing simple listing of qualitative contents and the inconsistent presentation of review opinions by consultative agencies and review agencies. Research design, data and methodology: The research method extracted absolute evaluation items and relative evaluation items among small environmental impact assessment items, analyzed and presented detailed items, and prepared a distribution table for each section according to the details of the relative evaluation items, and presented them as a table. Results: This study was conducted to derive uniform results with objective indicators in the preparation and consultation process of a small-scale environmental impact assessment. Conclusions: Once a quantitative evaluation is established, the consultant can objectively determine and process the environmental impact.

• 대한기계학회논문집A
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• 제36권3호
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• pp.339-346
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• 2012

철도차량의 집전성능 및 이선율에 대한 사전 평가는 철도차량의 고속화와 더불어 중요시되는 문제이다. 본 논문에서는 유연체 다물체 동역학 해석 기법을 이용하여 가선과 판토그래프 사이의 동적상호작용에 대한 시뮬레이션 모델을 개발하였다. 해석 모델에서 판토그래프는 강체로 모델링 하였으며, 가선계는 탄성 대변형체의 거동을 효과적으로 표현할 수 있는 절대절점좌표를 이용하여 구현하였다. 또한, 가선계와 판토그래프 간의 동적 상호작용의 표현을 위하여 서로간의 상대운동은 슬라이딩 조인트를 이용하여 구속하였다. 개발된 해석 프로그램을 이용하여 철도차량의 주행 속도에 따라 발생하는 접촉력 및 이선율을 평가하였다. 개발 프로그램의 해석 모델 및 시뮬레이션에 대한 신뢰성은 가선계와 판토그래프의 동적 상호작용 시뮬레이션 방법에 대한 국제 규정인 EN 50318에 의하여 검증하였다. 해석 모델의 개발을 통하여 개발 중인 고속철도의 집전성능을 평가할 수 있는 기반을 마련하였다.

• Wind and Structures
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• 제26권6호
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• pp.383-395
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• 2018

An accurate determination of wind speed distribution is the basis for an evaluation of the wind energy potential required to design a wind turbine, so it is important to estimate unknown parameters of wind speed distribution. In this paper, Gumbel distribution is used in modelling wind speed data, and alternative robust estimation methods to estimate its parameters are considered. The methodologies used to obtain the estimators of the parameters are least absolute deviation, weighted least absolute deviation, median/MAD and least median of squares. The performances of the estimators are compared with traditional estimation methods (i.e., maximum likelihood and least squares) according to bias, mean square deviation and total mean square deviation criteria using a Monte-Carlo simulation study for the data with and without outliers. The simulation results show that least median of squares and median/MAD estimators are more efficient than others for data with outliers in many cases. However, median/MAD estimator is not consistent for location parameter of Gumbel distribution in all cases. In real data application, it is firstly demonstrated that Gumbel distribution fits the daily mean wind speed data well and is also better one to model the data than Weibull distribution with respect to the root mean square error and coefficient of determination criteria. Next, the wind data modified by outliers is analysed to show the performance of the proposed estimators by using numerical and graphical methods.