• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2002년도 춘계학술대회논문집
• /
• pp.1238-1243
• /
• 2002

In this study, the validity of the acoustic impedance model and the estimation model by electro-acoustic analogy suggested by Maa for predicting the absorptive performance of multiple layer perforated plate systems is investigated. From the comparison between the experiment and calculation for the absorption performance of double layer perforated plate system, the calculated results of using Rao and Munjal's impedance model and transfer matrix method are closer to the experimental values than those of using Maa's impedance model and electro-acoustic analogy. Therefore, in order to apply the acoustic impedance model and the estimation model by electro-acoustic analogy suggested by Maa to the multiple layer perforated plate systems, it is necessary that the suggested acoustic impedance and estimation models should be re-examined.

• 대한전기학회논문지:전력기술부문A
• /
• 제52권8호
• /
• pp.450-456
• /
• 2003

This paper proposes a multiple time-series model with dummy variables for one-hour ahead load forecasting. We used 11 dummy variables that were classified by day characteristics such as day of the week, holiday, and special holiday. Also, model specification and selection of input variables including dummy variables were made by test statistics such as AIC(Akaike Information Criterion) and t-test statistics of each coefficient. OLS (Ordinary Least Squares) method was used for estimation and forecasting. We found out that model specifications for each hour are not identical usually at 30％ of optimal significance level, and dummy variables reduce the forecasting error if they are classified properly. The proposed model has much more accurate estimates in forecasting with less MAPE (Mean Absolute Percentage Error).

• 경영과학
• /
• 제28권3호
• /
• pp.1-13
• /
• 2011

Hub-and-spoke transportation network is a powerful and useful network structure that takes full advantage of economies of scale on routes between hubs. In recent studies, the network structure is extended to hybrid hub-andspoke that allows direct transportation between spokes. In this study, we considered more extended network structure which is called hybrid multiple hub-and-spoke that has multiple hubs and allows direct transportation between spokes. We developed a mathematical optimization model for automotive service parts transportation planning under hybrid multiple hub-and-spoke network structure. The model suggests a long-term transportation route planning and a short-term vehicle assignment planning. The model is verified by simulation and validated in real world application to Hyundai Mobis automotive service parts transportation planning. From the simulation result, the model reduced the transportation cost about 24.7%, the total distance about 6.8% and the CO2 emissions about 8.8%. In real world application for 6 months from July to December 2010, the model reduced the transportation cost about 9.1% by changing the long-term transportation route without daily vehicle assignment planning.

• 물과 미래
• /
• 제28권1호
• /
• pp.81-90
• /
• 1995

본 연구에서는 장기간의 수문기상자료를 보유하고 있으나 유출량자료의 관측년한이 짧은 유역에서 장기간의 월유출량자료를 확장하고 예측할 수 있는 추계학적 시스템 모형을 개발하고자 한다. 그 방법으로 주기성과 경향성을 갖는 월유출량, 월강수량 및 윌증발량자료를 시계열 분석하여 seasonal ARIMA 형태의 단변량 모형을 유도하는 한편, 각 계열간의 교차상관분석으로부터 월강수량 및 윌증발량을 입력변수로 하고 월유출량을 출력변수로 하는 다중 입력-단일 출력관계의 설명모형을 유도하여 단변량 시계열모형과 비교 검토하였다. 본 연구의 결과 월유출량자료의 확장과 예측에 있어서 다중 입출력모형의 정확성과 적용가능성이 매우 높은 것으로 판단되었다.

• 한국전자통신학회논문지
• /
• 제8권8호
• /
• pp.1201-1206
• /
• 2013

영상에서 얼굴 및 얼굴 특징을 추출하기 위한 기법으로 active appearance model(AAM)이 있다. 본 논문에서는 두 개의 AAM을 이용하여 얼굴 특징을 추출하는 multiple active appearance model(MAAM) 기법을 제안한다. 두 개의 AAM은 학습 데이터에 대한 파라미터를 조절하여 상반되는 장단점을 가지도록 생성하고, 서로의 단점을 보완할 수 있도록 한다. 제안된 방법의 성능을 평가하기 위해 100장의 영상에 대해서 얼굴 특징추출 실험을 하였다. 실험 결과 기존의 AAM 하나만을 사용하는 기법에 비해 적은 횟수의 피팅만으로도 정확도 높은 결과를 얻을 수 있었다.

• 한국건축시공학회지
• /
• 제13권1호
• /
• pp.66-74
• /
• 2013

In the early stages of a construction project, the most important thing is to predict construction costs in a rational way. For this reason, many studies have been performed on the estimation of construction costs for apartment housing and office buildings at early stage using artificial intelligence, statistics, and the like. In this study, cost data held by a provincial Office of Education on elementary schools constructed from 2004 to 2007 were used to compare the multiple regression model with an artificial neural network model. A total of 96 historical data were classified into 76 historical data for constructing models and 20 historical data for comparing the constructed regression model with the artificial neural network model. The results of an analysis of predicted construction costs were that the error rate of the artificial neural network model is lower than that of the multiple regression model.

• International Journal of Fuzzy Logic and Intelligent Systems
• /
• 제6권1호
• /
• pp.39-46
• /
• 2006

We propose an global color model based method for tracking motions of multiple human using a networked multiple-camera system in intelligent space as a human-robot coexistent system. An intelligent space is a space where many intelligent devices, such as computers and sensors(color CCD cameras for example), are distributed. Human beings can be a part of intelligent space as well. One of the main goals of intelligent space is to assist humans and to do different services for them. In order to be capable of doing that, intelligent space must be able to do different human related tasks. One of them is to identify and track multiple objects seamlessly. In the environment where many camera modules are distributed on network, it is important to identify object in order to track it, because different cameras may be needed as object moves throughout the space and intelligent space should determine the appropriate one. This paper describes appearance based unknown object tracking with the distributed vision system in intelligent space. First, we discuss how object color information is obtained and how the color appearance based model is constructed from this data. Then, we discuss the global color model based on the local color information. The process of learning within global model and the experimental results are also presented.

• 한국시뮬레이션학회논문지
• /
• 제13권1호
• /
• pp.41-50
• /
• 2004

The purpose of this paper is to analyse the manager's policy to maximize the profit in a multiple-server queueing facility with a limited queue capacity. We assume that the level of advertizing effects on the arrival rate of customers to the facility. The model without ‘word of mouth effect’ is assumed that the arrival rate is independent on the qualify of service level. We estimate the service quality by the balking rate of customers from system. We extend this to the model with ‘word of mouth effect’. To achieve the maximum profit, the most important factor is the considerably high utilization of facility for both models. Given service rate, we should maintain an effective arrival rate to some extent. To this end, among the available options, an increase of advertizing effort is more desirable than reducing the fee if the service value of customers remains unchanged. We also investigate whether the variability of service time has a significant impact on determining the optimal policy. The cost of service variability is not so expensive as that in a single server model due to the reduced variability of service times in a multiple-server model.

• 대한원격탐사학회지
• /
• 제25권3호
• /
• pp.271-285
• /
• 2009

Multi-temporal satellite imagery can be changed into a transform image that emphasizes the changed area only through the application of various change detection techniques. From the transform image, an automated change detection model calculates the optimal threshold value for classifying the changed and unchanged areas. However, the model can cause undesirable results when the histogram of the transform image is unbalanced. This is because the model uses a single threshold value in which the sign is either positive or negative and its value is constant (e.g. -1, 1), regardless of the imbalance between changed pixels. This paper proposes an advanced method that can improve accuracy by applying separate threshold values according to the increased or decreased range of the changed pixels. It applies multiple threshold values based on the cumulative producer's and user's accuracies in the automated binary change detection model, and the analyst can automatically extract more accurate optimal threshold values. Multi-temporal IKONOS satellite imagery for the Daejeon area was used to test the proposed method. A total of 16 transformation results were applied to the two study sites, and optimal threshold values were determined using accuracy assessment curves. The experiment showed that the accuracy of most transform images is improved by applying multiple threshold values. The proposed method is expected to be used in various study fields, such as detection of illegal urban building, detection of the damaged area in a disaster, etc.

• 한국안전학회지
• /
• 제33권6호
• /
• pp.37-41
• /
• 2018

Process safety technology has developed from qualitative methods such as HAZOP (hazard and operability study) to semi-quantitative methods such as LOPA (layer of protection analysis), and quantitative methods are actively studied these days. Quantitative risk assessment (QRA) is often based on fault tree analysis (FTA). FTA is efficient, but difficult to apply when failure events are not independent of each other. This problem can be avoided using a Markov process (MP). MP requires definition of all possible states, and thus, generally, is more complicated than FTA. A method is proposed in this work that uses an MP model and a Weibull distribution model in order to construct a reliability model for multiple dependent failures. As a case study, a pressure safety valve (PSV) is considered, for which there are three kinds of failure, i.e. open failure, close failure, and gas tight failure. According to recently reported inspection results, open failure and close failure are dependent on each other. A reliability model for a PSV group is proposed in this work that is to reproduce these results. It is expected that the application of the proposed method can be expanded to QRA of various systems that have partially dependent multiple failure states.