• 제목/요약/키워드: multi-sample problem

검색결과 84건 처리시간 0.021초

월성1호기 사용후 핵연료 건식저장 캐니스터의 열적 안전성에 미치는 대기 조건 인자의 영향 (Parametric Effects of Ambient Conditions on Thermal Safety of Wolsong (CANDU) Unit 1 Spent Fuel Dry Storage Canister)

  • Park, Jong-Woon;Chun, Moon-Hyun;Shon, Soon-Hwan;Song, Myung-Jae
    • Nuclear Engineering and Technology
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    • 제25권1호
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    • pp.166-177
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    • 1993
  • 사용후 핵연료 건식 저장 캐니스터의 핵연료 바스켓 안에 있는 CANDU 37소자 핵연료 다발의 최대 온도를 계산하기 위한 단순화된 열해석 방법과 함께 대기 조건 인자들이 캐니스터 내부의 최대 핵연료 온도에 미치는 영향을 조사하기 위해 수행한 표본 해석 결과를 제시하였다. 3가지 모우드(mode)의 열전달이 공존하는 캐니스터 내부핵연료 다발의 복잡한 기하학적 구조에 대한 다차원열전달 문제를 풀기 위하여 건식저장 캐니스터에 저장된 CANDU 사용후 핵연료 다발들을 등가 및 동심의 핵연료 실린더(cylinder)로 대치하였다. 추가적인 입력 자료 및 열전달 상관식을 이용하여 등가 핵연료 실린더의 단순화된 축대칭, 2차원, 복수 모우드(multi-mode)의 열전달 문제를 기존의 컴퓨터 코드인 HEATING5로 해석하였다. 예측한 온도 분포와 식물 모형 실험 결과의 비교는 만족스러울 정도로 일치함을 보여주고 있다.

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다분류 SVM을 이용한 DEA기반 벤처기업 효율성등급 예측모형 (The Prediction of DEA based Efficiency Rating for Venture Business Using Multi-class SVM)

  • 박지영;홍태호
    • Asia pacific journal of information systems
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    • 제19권2호
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    • pp.139-155
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    • 2009
  • For the last few decades, many studies have tried to explore and unveil venture companies' success factors and unique features in order to identify the sources of such companies' competitive advantages over their rivals. Such venture companies have shown tendency to give high returns for investors generally making the best use of information technology. For this reason, many venture companies are keen on attracting avid investors' attention. Investors generally make their investment decisions by carefully examining the evaluation criteria of the alternatives. To them, credit rating information provided by international rating agencies, such as Standard and Poor's, Moody's and Fitch is crucial source as to such pivotal concerns as companies stability, growth, and risk status. But these types of information are generated only for the companies issuing corporate bonds, not venture companies. Therefore, this study proposes a method for evaluating venture businesses by presenting our recent empirical results using financial data of Korean venture companies listed on KOSDAQ in Korea exchange. In addition, this paper used multi-class SVM for the prediction of DEA-based efficiency rating for venture businesses, which was derived from our proposed method. Our approach sheds light on ways to locate efficient companies generating high level of profits. Above all, in determining effective ways to evaluate a venture firm's efficiency, it is important to understand the major contributing factors of such efficiency. Therefore, this paper is constructed on the basis of following two ideas to classify which companies are more efficient venture companies: i) making DEA based multi-class rating for sample companies and ii) developing multi-class SVM-based efficiency prediction model for classifying all companies. First, the Data Envelopment Analysis(DEA) is a non-parametric multiple input-output efficiency technique that measures the relative efficiency of decision making units(DMUs) using a linear programming based model. It is non-parametric because it requires no assumption on the shape or parameters of the underlying production function. DEA has been already widely applied for evaluating the relative efficiency of DMUs. Recently, a number of DEA based studies have evaluated the efficiency of various types of companies, such as internet companies and venture companies. It has been also applied to corporate credit ratings. In this study we utilized DEA for sorting venture companies by efficiency based ratings. The Support Vector Machine(SVM), on the other hand, is a popular technique for solving data classification problems. In this paper, we employed SVM to classify the efficiency ratings in IT venture companies according to the results of DEA. The SVM method was first developed by Vapnik (1995). As one of many machine learning techniques, SVM is based on a statistical theory. Thus far, the method has shown good performances especially in generalizing capacity in classification tasks, resulting in numerous applications in many areas of business, SVM is basically the algorithm that finds the maximum margin hyperplane, which is the maximum separation between classes. According to this method, support vectors are the closest to the maximum margin hyperplane. If it is impossible to classify, we can use the kernel function. In the case of nonlinear class boundaries, we can transform the inputs into a high-dimensional feature space, This is the original input space and is mapped into a high-dimensional dot-product space. Many studies applied SVM to the prediction of bankruptcy, the forecast a financial time series, and the problem of estimating credit rating, In this study we employed SVM for developing data mining-based efficiency prediction model. We used the Gaussian radial function as a kernel function of SVM. In multi-class SVM, we adopted one-against-one approach between binary classification method and two all-together methods, proposed by Weston and Watkins(1999) and Crammer and Singer(2000), respectively. In this research, we used corporate information of 154 companies listed on KOSDAQ market in Korea exchange. We obtained companies' financial information of 2005 from the KIS(Korea Information Service, Inc.). Using this data, we made multi-class rating with DEA efficiency and built multi-class prediction model based data mining. Among three manners of multi-classification, the hit ratio of the Weston and Watkins method is the best in the test data set. In multi classification problems as efficiency ratings of venture business, it is very useful for investors to know the class with errors, one class difference, when it is difficult to find out the accurate class in the actual market. So we presented accuracy results within 1-class errors, and the Weston and Watkins method showed 85.7% accuracy in our test samples. We conclude that the DEA based multi-class approach in venture business generates more information than the binary classification problem, notwithstanding its efficiency level. We believe this model can help investors in decision making as it provides a reliably tool to evaluate venture companies in the financial domain. For the future research, we perceive the need to enhance such areas as the variable selection process, the parameter selection of kernel function, the generalization, and the sample size of multi-class.

Modified partial least squares method implementing mixed-effect model

  • Kyunga Kim;Shin-Jae Lee;Soo-Heang Eo;HyungJun Cho;Jae Won Lee
    • Communications for Statistical Applications and Methods
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    • 제30권1호
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    • pp.65-73
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    • 2023
  • Contemporary biomedical data often involve an ill-posed problem owing to small sample size and large number of multi-collinear variables. Partial least squares (PLS) method could be a plausible alternative to an ill-conditioned ordinary least squares. However, in the case of a PLS model that includes a random-effect, how to deal with a random-effect or mixed effects remains a widely open question worth further investigation. In the present study, we propose a modified multivariate PLS method implementing mixed-effect model (PLSM). The advantage of PLSM is its versatility in handling serial longitudinal data or its ability for taking a randomeffect into account. We conduct simulations to investigate statistical properties of PLSM, and showcase its real clinical application to predict treatment outcome of esthetic surgical procedures of human faces. The proposed PLSM seemed to be particularly beneficial 1) when random-effect is conspicuous; 2) the number of predictors is relatively large compared to the sample size; 3) the multicollinearity is weak or moderate; and/or 4) the random error is considerable.

다자유도 비강 자동 검체 채취 로봇 메커니즘 개발 (Development of Multi-DoF Automatic Nasopharyngeal Swab Sampling Robot)

  • 이종복;김호빈;김선우;김상도;이호석;김용재;박신석;이종원
    • 로봇학회논문지
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    • 제18권2호
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    • pp.164-171
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    • 2023
  • To control the spread of COVID-19, it is important to identify the infection in its incipient stages so that the infected persons can be dealt with accordingly. The currently used face to face sampling method may increase the risk of infection for medical professionals as it exposes them to the asymptomatic yet infectious patients. This can result in further increases in the load on the medical system and workload of the medical staff. As a solution to this problem, in this paper, we present a robotic system for rapid non-face-to-face automatic nasopharyngeal swab sample collection. The system consists of a custom designed 7-DoF manipulator equipped with a specially developed safety mechanism for restricting the maximum force applied by the tip of the swab. During the swab sampling process, the force applied by the tip of the swab is continuously monitored in real-time by a 3-axis force sensor in order to detect contact with the nasopharynx. The possibility of using this system for automaticnasopharyngeal swab sample collection is proven through experimentation with a phantom model.

IHP 알고리즘을 이용한 SIMO 시스템용 적응 직접 결정 등화기 연구 (An Adaptive Decision-Directed Equalizer using Iterative Hyperplane Projection for SIMO systems)

  • 이원철
    • 한국통신학회논문지
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    • 제30권1C호
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    • pp.82-91
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    • 2005
  • 본 논문은 iterative hyperplane projection 을 이용한 효율적인 APA(affine projection algorithm)을 소개한다. 다양한 적응 알고리즘들 중 APA는 랭크 부족 문제를 해결하며 고속 수렴의 특성 때문에 다양한 응용분야에 적용되고 있다. SIMO(Single-Input-Multiple-Output) 시스템을 위한 STDE(Space-Time Decision- directed Equalizer) 적용 시 흔히 단일 채널 환경에서 발생하는 "shifting invariance property"를 이용할 수 없으므로 인해 FTF(Fast Transversal Filter)와 같이 저 복잡도를 갖는 고속 적응 알고리즘을 사용할 수 없다. 따라서 APA 기반의 STDE 기능을 수행하는 과정에서 SMI(Sample Matrix Inversion) 처리가 불가피하며, 계산상의 복잡도가 증가하게 된다. 이러한 문제점을 해결하고자 본 논문에서는 APA 기법 고유의 우수한 추적 특성 및 고속 수렴 성질을 유지하면서, 낮은 복잡도를 갖는 IHP(Iterative Hyperplane Projection) 알고리즘 기반의 효율적인 수정 APA 기법을 소개한다. 제안된 IHP 기반 APA 기법의 성능을 확인하기 위하여, 무선 SIMO 채널 환경 하에서 제안된 IHP-APA 알고리즘을 적용한 STED에 대한 비트 에러 오률 (BER) 특성과 계산량 분석을 통해서 우수성을 입증하였다.

대학교 음주관련 정책 환경이 대학생 음주문제에 미친 영향 (Effects of Policy and Environmental Characteristics of University on Drinking Problems among University Students)

  • 김광기;제갈정;이기일;박정은
    • 보건교육건강증진학회지
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    • 제29권2호
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    • pp.83-91
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    • 2012
  • Objectives: This study is to examine that drinking problems among university students were accounted for not only by student's individual characteristics but alcohol policy and environmental characteristics of the university in which students were enrolled. Method: Secondary data analysis was employed in which variables under study were derived from a raw data of a nationwide representative sample in 2009. Raw data under analysis included 3,665 students from 63 universities across Korea. Organizational and environmental characteristics of the university were collected from university administrators while individual characteristics and drinking behavior from the students in using self-administrated questionnaire. Multilevel regression analyses were employed to describe alcohol policy effects on students's drinking problems measured by AUDIT by using HLM7.0. Results: ICCs indicate that variation in drinking problem depends on alcohol policy of university. Multilevel regression models identified statistically significant factors in explaining variance of drinking problems. Group means on drinking problem are affected by indicators representing alcohol policy with level of drinking problem of student being decreased in accordance to level of availability of alcohol on campus. Conclusions: It is concluded that drinking problems among university students were associated with both individual characteristics and alcohol policy of the university they enrolled. This study supports policy belief that interventions at environmental as well as individual level are required to prevent drinking problem among university students.

Search for Ultra-faint Dwarfs in the Halo of M60, Giant Elliptical Galaxy in Virgo

  • LEE, JEONG HWAN;LEE, MYUNG GYOON;JANG, IN SUNG
    • 천문학회보
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    • 제41권2호
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    • pp.63.2-63.2
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    • 2016
  • One of the well-known problems in the lambda cold dark matter (${\Lambda}CDM$) models is a missing satellite problem. The slope of the mass function of low mass galaxies predicted by ${\Lambda}CDM$ models is much steeper than that based on the luminosity function of dwarf galaxies in the local universe. This implies that the model prediction is an overestimate of low mass galaxies, or that the current census of dwarf galaxies in the local universe may be an underestimate of dwarf galaxies. Previous studies of galaxy luminosity functions to address this problem are based mostly on the sample of galaxies brighter than Mv ~ -10 in the nearby galaxies. In this study we try to search for ultra-faint galaxies (UFDs), which are much fainter than those in the previous studies. We use multi-field HST ACS images of M60 in the archive. M60 is a giant elliptical galaxy located in the east part of the Virgo cluster, and hosts a large population of globular clusters and UCDs. Little is known about the dwarf galaxies in this galaxy. UFDs are much fainter, much smaller, and have lower surface brightness than normal dwarf galaxies so HST images of massive galaxies are an ideal resource. We present preliminary results of this search.

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Registration of Aerial Image with Lines using RANSAC Algorithm

  • Ahn, Y.;Shin, S.;Schenk, T.;Cho, W.
    • 한국측량학회지
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    • 제25권6_1호
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    • pp.529-536
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    • 2007
  • Registration between image and object space is a fundamental step in photogrammetry and computer vision. Along with rapid development of sensors - multi/hyper spectral sensor, laser scanning sensor, radar sensor etc., the needs for registration between different sensors are ever increasing. There are two important considerations on different sensor registration. They are sensor invariant feature extraction and correspondence between them. Since point to point correspondence does not exist in image and laser scanning data, it is necessary to have higher entities for extraction and correspondence. This leads to modify first, existing mathematical and geometrical model which was suitable for point measurement to line measurements, second, matching scheme. In this research, linear feature is selected for sensor invariant features and matching entity. Linear features are incorporated into mathematical equation in the form of extended collinearity equation for registration problem known as photo resection which calculates exterior orientation parameters. The other emphasis is on the scheme of finding matched entities in the aide of RANSAC (RANdom SAmple Consensus) in the absence of correspondences. To relieve computational load which is a common problem in sampling theorem, deterministic sampling technique and selecting 4 line features from 4 sectors are applied.

건축물의 피난계획에 관한 기초적 연구 (A Basic Study on the Evacuation Plans of Buildings)

  • 고치원
    • 한국화재소방학회논문지
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    • 제14권4호
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    • pp.1-6
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    • 2000
  • With the "Fire Protection Building Plan" of the Building Center of Japan as a sample, actual evacuation plans used for large scaled and multi-storied buildings are analyzed. Sufficient number of samples were classified into 6 categories. For room evacuation, time to pass through the exit was the most critical point for larger spaces and movement time in the room was the key for smaller evacuation object zone and less number of evacuees. Seen from the location of fire breakout point, it was witnessed that the numbers of crowding at the exits of the fire escape staircase are serious for floor level evacuation. For vertical traffic line, it was actually proved that time to fire escaping floor is problem of higher buildings. It was also proved that special evacuation methods are in practical use in many buildings in japan.

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Robust Predictive Feedback Control for Constrained Systems

  • Giovanini, Leonardo;Grimble, Michael
    • International Journal of Control, Automation, and Systems
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    • 제2권4호
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    • pp.407-422
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    • 2004
  • A new method for the design of predictive controllers for SISO systems is presented. The proposed technique allows uncertainties and constraints to be concluded in the design of the control law. The goal is to design, at each sample instant, a predictive feedback control law that minimizes a performance measure and guarantees of constraints are satisfied for a set of models that describes the system to be controlled. The predictive controller consists of a finite horizon parametric-optimization problem with an additional constraint over the manipulated variable behavior. This is an end-constraint based approach that ensures the exponential stability of the closed-loop system. The inclusion of this additional constraint, in the on-line optimization algorithm, enables robust stability properties to be demonstrated for the closed-loop system. This is the case even though constraints and disturbances are present. Finally, simulation results are presented using a nonlinear continuous stirred tank reactor model.