• Title/Summary/Keyword: Sample selection model

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The Effect of Sports Club Membership Lifestyle on Choice Behavior

  • Sunmun Park;Shuo LI
    • International Journal of Advanced Culture Technology
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    • v.11 no.2
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    • pp.267-275
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    • 2023
  • The purpose of this study is to investigate the influence of sports center members' lifestyles on participation promotion and choice behavior. To this end, more specifically, we intend to establish and clarify a hypothetical model based on the preceding studies of facilitating factors and factors that continue to participate according to the lifestyle of sports center members. In order to achieve this research purpose, the study subjects were set as the population of male and female adults over 20 who are using sports centers in Gwangju Metropolitan City and Jeollanam-do in 2021. As for the sampling method, the sample was extracted using cluster random sampling, and 300 people were used for the actual analysis, excluding 60 copies of double-entry and insincere or unreliable questionnaires. The survey tool was modified and supplemented according to this study based on the questionnaire that had been verified for reliability and validity in previous studies, and all questionnaire items were composed of a 5-point scale. The statistical analysis used for data analysis was frequency analysis, exploratory factor analysis, reliability analysis, and multiple regression analysis using SPSS Windows 21.0 Version. The conclusions obtained in this study through data analysis by such methods and procedures are as follows. First, according to the lifestyle of sports center members, participation promotion factors were found to have a partial influence. Second, according to the lifestyle of sports center members, the selection behavior was found to have a partial influence. Third, it was found that the participation promotion factors of sports center members partially affected the choice behavior.

Evaluation of Regression Models in LOADEST to Estimate Suspended Solid Load in Hangang Waterbody (한강수계에서의 부유사 예측을 위한 LOADEST 모형의 회귀식의 평가)

  • Park, Youn Shik;Lee, Ji Min;Jung, Younghun;Shin, Min Hwan;Park, Ji Hyung;Hwang, Hasun;Ryu, Jichul;Park, Jangho;Kim, Ki-Sung
    • Journal of The Korean Society of Agricultural Engineers
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    • v.57 no.2
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    • pp.37-45
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    • 2015
  • Typically, water quality sampling takes place intermittently since sample collection and following analysis requires substantial cost and efforts. Therefore regression models (or rating curves) are often used to interpolate water quality data. LOADEST has nine regression models to estimate water quality data, and one regression model needs to be selected automatically or manually. The nine regression models in LOADEST and auto-selection by LOADEST were evaluated in the study. Suspended solids data were collected from forty-nine stations from the Water Information System of the Ministry of Environment. Suspended solid data from each station was divided into two groups for calibration and validation. Nash-Stucliffe efficiency (NSE) and coefficient of determination ($R_2$) were used to evaluate estimated suspended solid loads. The regression models numbered 1 and 3 in LOADEST provided higher NSE and $R_2$, compared to the other regression models. The regression modes numbered 2, 5, 6, 8, and 9 in LOADEST provided low NSE. In addition, the regression model selected by LOADEST did not necessarily provide better suspended solid estimations than the other regression models did.

Emission Estimation and Exposure to Hazardous Gaseous Pollutants Associated with Use of Air Fresheners Indoors (실내 방향제 사용에 의한 유해 가스상 오염물질 배출 산정 및 노출 평가)

  • Jo, Wan-Kuen;Shin, Seung-Ho;Kwon, Gi-Dong;Lee, Jong-Hyo
    • Environmental Analysis Health and Toxicology
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    • v.24 no.2
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    • pp.137-148
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    • 2009
  • This study quantitatively investigated the emissions of indoor air pollutants associated with the utilization of air fresheners indoors, and evaluated individual exposure to five specified indoor air pollutants, which were chosen on the basis of selection criteria. An electrically-polished stainless steel chamber (50L) was employed to achieve this purpose. Test air fresheners were selected through three steps: first, on the basis of market sales; second, on the basis on a preliminary head-space study; and lastly, on the basis of emissions of toxic compounds (benzene, ethyl benzene, limonene, toluene, and xylene). The empirical mathematical model fitted well with the time-series concentrations in the environmental chamber (in most cases, determination coefficient, $R^2{\gtrsim}$0.9), thereby suggesting that the empirical model was suitable for testing emissions. The concentration equilibrium appeared 180 min after the introduction of sample air fresheners into the chamber. Both the chamber concentrations of emission rates or factors varied greatly according to air freshener type. It is noteworthy that although benzene, ethyl benzene, toluene, and xylene were emitted from all test air fresheners, their exposure levels were not significant enough to result in any significant health risk. However, certain type of air fresheners were observed to emit significant amount of limonene, which is potentially reactive with ozone to generate secondary pollutants with oxidants such as ozone, hydroxyl radicals, and nitrogen oxides. The exposure levels to limonene associated with the utilization of three air fresheners were estimated to be 13 to 175 times higher than that of other air fresheners. This information can help consumers to select low-pollutant-emitting air fresheners.

Social Benefits of Improved Water Quality at the Taehwa River Based on Citizen's Willingness-to-Pay (시민지불의사에 기초한 태화강 수질개선의 사회적 편익)

  • Kim, Jae-Hong
    • Journal of Environmental Policy
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    • v.6 no.1
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    • pp.83-109
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    • 2007
  • This study evaluates citizen's willingness-to-pay for the benefits from improved water quality of the Taehwa river in Ulsan, Korea, using a contingent valuation method with double-bounded dichotomous choice. The estimation results of the bivariate probit model shows the amounts of willingness-to-pay are monthly 3,458.5 Korean Won per household and yearly 14,760 million Korean Won for total households in Ulsan, Korea. These estimates are equivalent to the social values of improved water quality of the Taehwa river. This study also tests the inter-dependence between two answers, which may occur in the responses of the questions for the double-bounded dichotomous choice, and all the null hypotheses on the inter-dependence are rejected in this study.

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CFD Study for the Design of Coolant Path in Cryogenic Etch Chuck

  • Jo, Soo Hyun;Han, Ji Hee;Kim, Jong Oh;Han, Hwi;Hong, Sang Jeen
    • Journal of the Semiconductor & Display Technology
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    • v.20 no.2
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    • pp.92-97
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    • 2021
  • The importance of processes in cryogenic environments is increasing in a way to address problems such as critical dimension (CD) narrow and bottlenecks in micro-processing. Accordingly, in this paper, we proceed with the design and analysis of Electrostatic Chuck(ESC) and Coolant in cryogenic environments, and present optimal model conditions to provide the temperature distribution analysis of ESC in these environments and the appropriate optimal design. The wafer temperature uniformity was selected as the reference model that the operating conditions of the refrigerant of the liquid nitrogen in the doubled aluminum path were excellent. Design of simulation (DOS) was carried out based on the wheel settings within the selected reference model and the classification of three mass flow and diameter case, respectively. The comparison between factors with p-value less than 0.05 indicates that the optimal design point is when five turns of coolant have a flow rate of 0.3 kg/s and a diameter of 12 mm. ANOVA determines the interactions between the above factor, indicating that mass flow is the most significant among the parameters of interests. In variable selection procedure, Case 2 was also determined to be superior through the two-Sample T-Test of the mean and variance values by dividing five coolant wheels into two (Case 1 : 2+3, Case 2: 3+2). Finally, heat transfer analysis processes such as final difference method (FDM) and heat transfer were also performed to demonstrate the feasibility and adequacy of the analysis process.

A Simple Model of Shrinkage Cracking Development for Kaolinite (수축 균열 발달 과정을 위한 단순 모델)

  • Min, Tuk-Ki;Nhat, Vo Dai
    • Journal of the Korean Geotechnical Society
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    • v.23 no.9
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    • pp.29-37
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    • 2007
  • The experiments have been conducted on Kaolinite in laboratory to investigate the development of shrinkage cracking and propose a simple model. Image analysis method consisting of control point selection(CPS) technique is used to process and analyze images of soil cracking captured by a digital camera. The distributions of crack length increment and crack area increment vary as a three-step process. These steps are regarded as stages of soil cracking. They are in turn primary crack, secondary crack and shrinkage crack stages. In case of crack area, the primary and secondary stages end at normalized gravimetric water content(NGWC) of 0.92 and 0.70 for different specimen thicknesses respectively. In addition, the primary stage in case of crack length also ends at NGWC of 0.92 while the secondary stage stops at NGWC of 0.79, 0.82, and 0.85 for the sample thicknesses of 0.5, 1.0, and 2.0 cm respectively Based on the experimental results, the distributions of crack length increment and crack area increment appear to be linear with a decrease of NGWC. Therefore, the development of shrinkage cracking is proposed typically by a simple model functioned by a combination of three linear expressions.

Development and Validation Study of the Korean Version of Working Relationship Scale (한국형 실천관계 척도 정신장애인 용 개발 연구)

  • Kwon, Jayoung
    • Korean Journal of Social Welfare
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    • v.65 no.3
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    • pp.239-263
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    • 2013
  • This research was carried out in order to develop and validate the Korean Version of Working Relationship Scale for Mentally Disabled Persons, which measures the working relationship between a mentally disabled person and his or her case manager. The first step taken to develop this scale was to construct sample items for the Working Relationship Scale using literature research and three focus group interviews of mentally disabled persons who use local mental health services. Secondly, mentally disabled people were surveyed with these sample items and two professors from the department of social work who specialize in mental health social work and two licensed mental health social workers working in the community mental health field reviewed these sample items to select and compile a final version of the scale. Lastly, the scale's reliability and validity was verified through an empirical study of 569 mentally disabled persons who surveyed the final selection of items. An explanatory factor analysis showed that the sample items can be grouped into three factors. Factor 1 is 'Professional Contribution Factor,' which is related to the professional practice of the case manager; Factor 2 is 'Negative Working Relationship Factor'; and Factor 3 is 'Emotional Bond Factor,' which measures the intimacy between the case manager and the mentally disabled person. A confirmatory analysis of the three-factor format that was discovered in the explanatory factor analysis was carried out with the rest of the randomly divided data, which showed that the model demonstrated a goodness-of-fit. The convergence validity between similar concepts appeared to be appropriate as well. Based on these results, the Korean Version of Working Relationship Scale for Mentally Disabled Persons consisting of a final 33 items is developed and proposed and its implications in social work are discussed.

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A Study on the Optimal Discriminant Model Predicting the likelihood of Insolvency for Technology Financing (기술금융을 위한 부실 가능성 예측 최적 판별모형에 대한 연구)

  • Sung, Oong-Hyun
    • Journal of Korea Technology Innovation Society
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    • v.10 no.2
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    • pp.183-205
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    • 2007
  • An investigation was undertaken of the optimal discriminant model for predicting the likelihood of insolvency in advance for medium-sized firms based on the technology evaluation. The explanatory variables included in the discriminant model were selected by both factor analysis and discriminant analysis using stepwise selection method. Five explanatory variables were selected in factor analysis in terms of explanatory ratio and communality. Six explanatory variables were selected in stepwise discriminant analysis. The effectiveness of linear discriminant model and logistic discriminant model were assessed by the criteria of the critical probability and correct classification rate. Result showed that both model had similar correct classification rate and the linear discriminant model was preferred to the logistic discriminant model in terms of criteria of the critical probability In case of the linear discriminant model with critical probability of 0.5, the total-group correct classification rate was 70.4% and correct classification rates of insolvent and solvent groups were 73.4% and 69.5% respectively. Correct classification rate is an estimate of the probability that the estimated discriminant function will correctly classify the present sample. However, the actual correct classification rate is an estimate of the probability that the estimated discriminant function will correctly classify a future observation. Unfortunately, the correct classification rate underestimates the actual correct classification rate because the data set used to estimate the discriminant function is also used to evaluate them. The cross-validation method were used to estimate the bias of the correct classification rate. According to the results the estimated bias were 2.9% and the predicted actual correct classification rate was 67.5%. And a threshold value is set to establish an in-doubt category. Results of linear discriminant model can be applied for the technology financing banks to evaluate the possibility of insolvency and give the ranking of the firms applied.

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

  • Park, Ji-Young;Hong, Tae-Ho
    • Asia pacific journal of information systems
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    • v.19 no.2
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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.

Empirical Analysis of Selection Criteria of Container Ports in the Bay of Bengal (벵갈만 지역의 컨테이너항만 선택 기준에 관한 연구)

  • Lwin, Theingi;Kim, Hyundeok
    • Journal of Korea Port Economic Association
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    • v.34 no.4
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    • pp.69-84
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    • 2018
  • The purpose of this study is to provide a comparative evaluation of container port criteria at four major container ports in the Bay of Bengal, including Colombo Port in Sri Lanka, Chennai Port in India, Chittagong Port in Bangladesh and Yangon Port in Myanmar. Important container port selection criteria are identified and comparisons among container ports are made using previous studies, personal interviews and questionnaires, completed by top shipping companies, freight forwarders, logistics service providers, and experts in Myanmar. The AHP method is used to verify the research model and hypothesis. This study identified five main criteria and eleven sub-criteria when choosing potential regional hub ports among the four ports in the Bay of Bengal. The main findings from the five main criteria suggest that port efficiency is the highest priority criteria, and the second priority is port costs. The criteria of geographical location and available port facilities are the third and fourth most important, respectively, and the last priority is port's hinterland. Regarding the relative competition among these ports, Colombo Port obtained the highest priority among the four influential factors except for port hinterland. This study has certain limitations that will require future research. First, the sample group for the population size is relatively small. Second, interviewees had limited experience answering questionnaires using this methodology and a limited amount of time was available for respondents for the interviews.