• Journal of Information Processing Systems
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• 제8권4호
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• pp.621-652
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• 2012

Software Estimations provide an inclusive set of directives for software project developers, project managers, and the management in order to produce more realistic estimates based on deficient, uncertain, and noisy data. A range of estimation models are being explored in the industry, as well as in academia, for research purposes but choosing the best model is quite intricate. Estimation by Analogy (EbA) is a form of case based reasoning, which uses fuzzy logic, grey system theory or machine-learning techniques, etc. for optimization. This research compares the estimation accuracy of some conventional data mining models with a hybrid model. Different data mining models are under consideration, including linear regression models like the ordinary least square and ridge regression, and nonlinear models like neural networks, support vector machines, and multivariate adaptive regression splines, etc. A precise and comprehensible predictive model based on the integration of GRA and regression has been introduced and compared. Empirical results have shown that regression when used with GRA gives outstanding results; indicating that the methodology has great potential and can be used as a candidate approach for software effort estimation.

• 조명전기설비학회논문지
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• 제22권5호
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• pp.64-72
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• 2008

3상 4선식 전원공급에서 부하의 불평형 운전에 의한 전압 불평형은 전류 불평형을 일으켜 기기의 손실증가에 따른 출력 감소로 전원용량을 증가시키는 것은 물론이고 전기 품질에도 나쁜 영향을 미치고 있다. 전력용 커패시터는 유도성 부하의 역률 보상과 전원을 안정시키기 위해 사용되며, 유도전동기의 여자에 필요한 자화성분을 전원을 대신하여 제공하기도 한다. 전압 불평형이 지속될 경우 커패시터에 전압 스트레스로 작용하여 절연 고장을 일으킬 수 있다. 본 논문에서는 역률 개선용 커패시터가 전압 불평형 증가에 의해 받는 영향을 해석한 결과 전압 및 전류의 크기가 함께 증가하여 스트레스는 점차적으로 높아진다는 것을 확인할 수 있었다.

• 한국정보과학회논문지:시스템및이론
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• 제26권10호
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• pp.1258-1263
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• 1999

본 논문에서는 CRCW(Concurrent Read Concurrent Write)와 CREW(Concurrent Read Exclusive Write) PRAM(Parallel Random Access Machine) 모델에서 무방향성 그래프 G=(V, E)의 극대 매칭을 구하기 위해 간결한 랜덤 병렬 알고리즘을 제안한다. CRCW PRAM 모델에서 m개의 선을 가진 그래프에 대해, 제안된 매칭 알고리즘은 m개의 프로세서 상에서 {{{{ OMICRON (log m)의 기대 수행 시간을 가진다. 또한 CRCW 알고리즘을 CREW PRAM 모델에서 구현한 CREW 알고리즘은 OMICRON (log^2 m)의 기대 수행 시간을 가지지만,OMICRON (m/logm) 개의 프로세서만을 가지고 수행될 수 있다.Abstract This paper presents simple randomized parallel algorithms for finding a maximal matching in an undirected graph G=(V, E) for the CRCW and CREW PRAM models. The algorithm for the CRCW model has {{{{ OMICRON (log m) expected running time using m processors, where m is the number of edges in G We also show that the CRCW algorithm can be implemented on a CREW PRAM. The CREW algorithm runs in {{{{ OMICRON (log^2 m) expected time, but it requires only OMICRON (m / log m) processors.

• Journal of Information Science Theory and Practice
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• 제3권1호
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• pp.6-23
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• 2015

This study develops an effective method for sentiment analysis of user-generated content on drug review websites, which has not been investigated extensively compared to other general domains, such as product reviews. A clause-level sentiment analysis algorithm is developed since each sentence can contain multiple clauses discussing multiple aspects of a drug. The method adopts a pure linguistic approach of computing the sentiment orientation (positive, negative, or neutral) of a clause from the prior sentiment scores assigned to words, taking into consideration the grammatical relations and semantic annotation (such as disorder terms) of words in the clause. Experiment results with 2,700 clauses show the effectiveness of the proposed approach, and it performed significantly better than the baseline approaches using a machine learning approach. Various challenging issues were identified and discussed through error analysis. The application of the proposed sentiment analysis approach will be useful not only for patients, but also for drug makers and clinicians to obtain valuable summaries of public opinion. Since sentiment analysis is domain specific, domain knowledge in drug reviews is incorporated into the sentiment analysis algorithm to provide more accurate analysis. In particular, MetaMap is used to map various health and medical terms (such as disease and drug names) to semantic types in the Unified Medical Language System (UMLS) Semantic Network.

• 한국IT서비스학회지
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• 제11권1호
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• pp.211-221
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• 2012

Many metric-based classification models have been proposed to predict fault-proneness of software module. This paper presents two prediction models using Bayesian classifier which is one of the most popular modern classification algorithms. Bayesian model based on Bayesian probability theory can be a promising technique for software quality prediction. This is due to the ability to represent uncertainty using probabilities and the ability to partly incorporate expert's knowledge into training data. The two models, Na$\ddot{i}$veBayes(NB) and Bayesian Belief Network(BBN), are constructed and dimensionality reduction of training data and test data are performed before model evaluation. Prediction accuracy of the model is evaluated using two prediction error measures, Type I error and Type II error, and compared with well-known prediction models, backpropagation neural network model and support vector machine model. The results show that the prediction performance of BBN model is slightly better than that of NB. For the data set with ambiguity, although the BBN model's prediction accuracy is not as good as the compared models, it achieves better performance than the compared models for the data set without ambiguity.

• 정보처리학회논문지A
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• 제9A권4호
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• pp.589-594
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• 2002

컴퓨터 그래픽에서 L-시스템은 주로 나무나 풀, 꽃 등 자연적인 모습을 생성하기 위해 사용된다. 이는 임의로 제시된 최초의 모양에 다중 축소복사 이론을 반복적으로 적용함으로써 가능하다. 본 논문은 일반적인 L-시스템 나무의 모습을 변형하여 더욱 현실적으로 묘사하는데 목적이 있다. 본 논문에서는, L-시스템에서 사용되는 단순한 반복함수를 적용하는 대신에, 반복함수를 적용하는 과정에서 나뭇가지 하나하나를 생명체로 간주하여 생명체의 속성을 부여한다. 가지의 수명, 생장속도, 모양변화, 외부환경에 따른 유인 등 생명체가 지닌 속성은 파티클 시스템을 구성하는 입자들이 지닌 기본 속성이기도 하다. 속성의 적용을 위해서 개별 속성 별로 필요한 매개변수를 바탕으로 한 가설로서의 모델을 제시하고 결과적인 다양한 나무의 모습을 제시하였다.

• Progress in Superconductivity
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• 제14권1호
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• pp.52-59
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• 2012

In this paper, the robust superconductor flywheel energy storage system(SFESS) controller using $H_{\infty}$ control theory was designed to damp low frequency oscillation of power system. The main advantage of the $H_{\infty}$ controller is that uncertainties of power system can be included at the stage of controller design. Both disturbance attenuation and robust stability for the power system were treated simultaneously by using mixed sensitivity $H_{\infty}$ problem. The robust stability and the performance for uncertainties of power system were represented by frequency weighted transfer function. To verify control performance of proposed SFESS controller using $H_{\infty}$ control, the closed loop eigenvalue and the damping ratio in dominant oscillation mode of power system were analyzed and nonlinear simulation for one-machine infinite bus system was performed under disturbance for various operating conditions. The results showed that the proposed $H_{\infty}$ SFESS controller was more robust than conventional power system stabilizer (PSS).

• 수산해양기술연구
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• 제17권2호
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• pp.85-91
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• 1981

평판 강괴를 연속적으로 주조할 경우에 초기주조 상태에서 Mold 내부의 Support bar 및 용강자중, 주조속도, 용강두께, 이를 지지하는 제어 Roller, 유압기구, 구동 Motor, 그리고 주조조직의 응고 등이 용강의 인발력을 유도하는 Pinch Roller와의 사이에서 동력학적 부평형을 일으켜 Slip 현상을 초래하므로 본 논문에서는 이상의 제요인들을 근거로 Slip 현상을 규명하는 식을 유도하고 강괴의 주조속도, 비중량, 두께의 변화에 대한 Slip Force 거동을 규명하였다. 그 결과 1. 본 논문의 해석식에 의하여 평판강괴 연속주조용 Pinch Roller의 적정압을 설계할 수 있다. 2. 비중량은 순수히 자중만 증가시키는 요인이며 Slip Force는 주조속도변화에 대해서 포물선적으로 증가한다. 3. 주조두께 및 비중량의 변화에 대한 Slip Force는 이에 비례하여 증가하나 특히 두께의 값이 소폭보다 대폭에서 그 변화 값이 크게 나타났다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 추계학술대회 논문집
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• pp.1881-1888
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• 2008

As the ticket issuing methods have been diversified for the convenience of the passengers such as ticketless service(SMS ticket, e-ticket, home ticket), automatic ticket issuing machine and consignment ticket sale, maintaining the current number of ticket booth has been becoming a issue. Too many booth can cause the inefficiency of the cost of labor. According to the Charter of Customer Service of Korail, on the other hand, 95% of passengers have to purchase a train ticket within 5 minutes. This study was designed to present a decision making model for the optimum number of ticket booth which can affect an efficient operation of train station and improvement of customer convenience. And, this paper shows the proper manpower of ticket booth and the change of customer waiting time by analyzing the arrival and ticket issuing time of passengers based on 'Queueing Theory'. However, it is insufficient to be generalized due to some limitations of analysis. This study will contribute to improve customer satisfaction by reducing the waiting time at the ticket booth. In addition, presenting the optimum number of booth is expected to have an effect on the increase of productivity and cost savings.

• Advances in materials Research
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• 제2권4호
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• pp.181-193
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• 2013

Description and theory of spin coating technique has been elaborately outlined and a spin coating machine designed and fabricated using affordable components. The system was easily built with interdisciplinary knowledge of mechanics, fluid mechanics and electronics. This equipment employs majorly three basic components and two circuit units in its operation. These include a high speed dc motor, a proximity sensor mounted at a distance of about 15 mm from a reflective metal attached to the spindle of the motor to detect every passage of the reflective metal at its front and generate pulses. The pulses are transmitted to a micro-controller which process them into rotational speed (revolution per minute) and displays it on a lead crystal display (LCD) which is also a component of the micro-controller. The circuit units are a dc power supply unit and a PWM motor speed controlling unit. The various components and circuit units of this equipment are housed in a metal casing made of an 18 gauge black metal sheet designed with a total area of 1, $529.2cm^2$. To illustrate the use of the spin-coating system, ZnO sol-gel films were prepared and characterized using SEM, XRD, UV-vis, FT-IR and RBS and the result agrees well with that obtained from standard equipment and a speed of up to 9000 RPM has been achieved.