• Food Science of Animal Resources
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• v.42 no.2
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• pp.280-294
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• 2022

This study aimed to evaluate the effectiveness of propolis extract as a natural preservative for livestock products in term of chemical and microbiological characteristics by meta-analysis. The stages carried out in this study were identification, selection, checking suitability, and the resulting selected articles were used in the meta-analysis. The selection results obtained a total of 22 selected journal articles consisting of 9 articles for analysis of the antimicrobial activity of propolis extract and 13 articles for analysis of the chemical and mirobiological characteristics of livestock products. The articles were obtained from electronic databases, namely Science Direct and Google Scholar. The model used in this study is the random-effect model involving two groups, control and experimental. Heterogeneity and effect size values were carried out in this study using Hedge's obtained through openMEE software. Forest plot tests and data validation on publication bias was obtained using Kendall's test throught JASP 0.14.1 software. The results showed that there is a significant relationship between propolis extract with the results of the antimicrobial activity (p<0.05). In addition, the results of the application of propolis extract on the livestock products for the test microbes and the value of thiobarbituric acid reactive substances (TBARs) showed significant results (p<0.05). Conclusion based on the random-effect model on the effectiveness of antimicrobial activity of propolis extract and their apllication as a natural preservative of the chemical and microbiological characteristics of livestock products is valid by Kendall's test (p>0.05). Propolis in this case effectively used as natural preservatives in livestock products.

• Journal of Distribution Science
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• v.15 no.10
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• pp.41-50
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• 2017

Purpose - Online product review has become a crucial part of the online retailer's market performance for a wide range of products. This research aims to investigate how an individual reviewer's review frequency and timing affect her/his average attitude toward products. Research design, data, and methodology - To conduct reviewer-level analysis, this study uses 42,172 posted online review messages generated by 6,941 identified reviewers for 59 movies released in the South Korea from July 2015 to December 2015. This study adopts Tobit model specification to take into account the censored nature and the selection bias arising from the nature of J-shaped distribution of movie rating. Results - Our estimation results support that the negative impact of review frequency and timing on valence. Furthermore, review timing has an inverted-U relationship with the user's average valence and enhance the negative effect of review frequency. Conclusions - This study contributes to the growing literature on the understanding how eWOM is generated at the individual consumer level. On the basis of the main empirical findings, this study provides insights into building a recommendation system in online retail store based on the consumer's review history data - frequency, timing, and valence.

• The Korean Journal of Health Service Management
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• v.11 no.3
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• pp.65-78
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• 2017

Objectives : Obesity is a worldwide health concern due to an increasing obese population. This study proposed to analyze the differences in medical costs and care utilization between obese and normal group using propensity score matching. Methods : Data were collected from the sample cohort database by the Korea National Health Insurance Corporation. Propensity score matching(PSM) was applied to control selection bias, and factors affecting obesity were used as covariates in PSM. Results : The results showed higher medical costs and care utilization in the obese group than the normal group. According to gender and medical type, there were differences in the relationships between obesity and medical charges and utilization. In particular, the differences in the female population were larger in both outpatients and inpatients than the male population. Conclusions : It is important to manage obesity, because obesity has a negative effect on national health insurance costs. These findings suggest directions for future research.

• Human Ecology Research
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• v.55 no.3
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• pp.289-301
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• 2017

This study was to analyze the effects of the career education program for students with disabilities. The analysis was performed based on two research questions. First, the total effect size on the career program for students with disabilities was considered. Second, the difference of the effect size between the sub-groups regarding dependency variables, types of disabilities, types of schools, number of people, and number of sessions was also included for analysis. For this, the author reviewed a database and analyzed 12 previous studies, presented in five master thesis and seven Korean journals from 2005 to 2015 based on the author's selection criteria. Subsequently, 27 effect size was found. The publication bias was analyzed by Rosenthal's fail-safe N. The overall effect size for all studies on the random effect model was 1.717, which was positive and high in value. Given the heterogeneity among the effect size, the subgroup analysis was conducted, and indicated that the effect size was significantly high when the purpose of the program was related to the student's self-decision ability. The results demonstrated that the programs were specified for students with intellectual disabilities, when the schools were elementary, when the number of students in a group was 1-10, and when program sessions lasted more than 21 times, the effect size was high. Implication for the future research and program implication were discussed on these findings.

• The Korean Journal of Applied Statistics
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• v.29 no.7
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• pp.1361-1371
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• 2016

Quantile regression provides a variety of useful statistical information to examine how covariates influence the conditional quantile functions of a response variable. However, traditional quantile regression (which assume a linear model) is not appropriate when the relationship between the response and the covariates is a nonlinear. It is also necessary to conduct variable selection for high dimensional data or strongly correlated covariates. In this paper, we propose a penalized quantile regression tree model. The split rule of the proposed method is based on residual analysis, which has a negligible bias to select a split variable and reasonable computational cost. A simulation study and real data analysis are presented to demonstrate the satisfactory performance and usefulness of the proposed method.

• Information Systems Review
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• v.15 no.3
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• pp.141-149
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• 2013

When evaluating effectiveness of a government's supporting program, there is a tendency to simply compare the performances of the treated before and after the program or to compare the differences in the performances of the treated and untreated before-after the program. However, these ways of evaluating effectiveness have problems because they can't account for environmental changes affecting the treated or effects coming from the differences between the treated and the untreated. Therefore, in this paper, sequential applications of PSM and DID are suggested as a means to overcome those problems. It turns out that this approach enables us to eliminate self-selection bias and thus better evaluate effectiveness.

• Korean Management Science Review
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• v.27 no.1
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• pp.91-105
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• 2010

We proposed and stratified a selection standard model on Open Source Functional Board which could be found in Web. So we could grasp the weight about Performance Evaluation from the viewpoints of planners, developers, and web disigner professional of views. We suggested applying diverse measurement types in case of item which could chart Evaluation Standards on chosen sample boards. In case of item which couldn't do that, we compared and analyzed it by using selective type of 9 point scaling method on professionalists in every sample board. As a result of weight on upper estimate section of evaluation model chart, the order of importance was convenience(0.334), performance(0.333), function(0.240) and design(0.093) respectively. It indicates that there is more weight on performance and convenience which are hard to be structurally modified than designs and functions that are directly shown to the users. Also, it was evident that opposite results came out when using 9-point scale survey and measurement with objective data such as function and performance. The reason is because the surveyed subject can have his or her own subjectivity and bias unlike objective data. However, objectivity of the administrator is also an important factor thus both two perspectives have to be all considered when selecting the bulletin board.

• Communications for Statistical Applications and Methods
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• v.24 no.5
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• pp.493-505
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• 2017

Maximum likelihood estimation (MLE) of the generalized extreme value distribution (GEVD) is known to sometimes over-estimate the positive value of the shape parameter for the small sample size. The maximum penalized likelihood estimation (MPLE) with Beta penalty function was proposed by some researchers to overcome this problem. But the determination of the hyperparameters (HP) in Beta penalty function is still an issue. This paper presents some data adaptive methods to select the HP of Beta penalty function in the MPLE framework. The idea is to let the data tell us what HP to use. For given data, the optimal HP is obtained from the minimum distance between the MLE and MPLE. A bootstrap-based method is also proposed. These methods are compared with existing approaches. The performance evaluation experiments for GEVD by Monte Carlo simulation show that the proposed methods work well for bias and mean squared error. The methods are applied to Blackstone river data and Korean heavy rainfall data to show better performance over MLE, the method of L-moments estimator, and existing MPLEs.

• The Journal of Korean Medicine
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• v.21 no.4
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• pp.129-137
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• 2000

Objectives: The aim of this study was to investigate the attitude toward the oriental hospital among 1,234 outpatients. Methods: A questionnaire about the general characteristics of patients, the decision-maker of use and the reason of choice or alteration was implemented. Results: The results of this survey as follows: Among outpatients 56.4 % were female in sex, 25.6 % were below 9 years of age; in educational level, 50.1 % were college graduates. Among outpatients, 33.6% chose the oriental hospital as their first choice and the rest were recommended by other persons. The recommenders were mostly relatives(73.9 %), female(73.4 %), young(30-39 years old, 40.1 %), high educational level (above the college, 54.9 %) people. 37.8 % among outpatients were secondary selection after the western medical clinic for the same symptom and sign. 7.0 % were the concomitant users of both therapies. 62.8 % among the concomitant users did not notify the western doctor about the dual therapies. The reasons they did not notify their Western doctors were 'be afraid of western doctor s bias' (42.6 %), 'no special reason' (29.6 %). Conclusions: The appropriate transfer system between oriental and western clinic must be constructed and the proper recognition about dual therapies will be needed among patients and doctors who practice both kinds of medicine.

• The Journal of Korean Medicine
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• v.41 no.1
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• pp.93-106
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• 2020

Objectives: The aim of this review is to ascertain whether Bojungikgi-tang and its modifications is more effective than non-specific management in chronic fatigue syndrome (CFS). Methods: We collected clinical trials to investigate the effects of Bojungikgi-tang and non-specific management on general symptoms, fatigue, and sleep quality in CFS patients. The databases used for data retrieval were Pubmed, Central Cochrane, CNKI, VIP, CiNii, OASIS, RISS, and Koreamed. We performed selection/exclusion process from the found records according to prespecified criteria, and assessed the final included trials according to the Cochrane risk of bias tool. The included studies were classified on the basis of interventions in experimental group. Results: Seven randomized controlled trials (476 participants) were eligible and their results were synthesized in the meta-analysis. The synthesis showed a substantial effect of Bojungikgi-tang (relative risk 0.20 [95% CI 0.13 to 0.31], Z=7.44, P<0.00001; I²=0%) and combination of Bojungikgi-tang and Sosiho-tang (relative risk 0.15 [95% CI 0.08 to 0.28], Z=5.85, P<0.00001; I²=0%) compared with non-specific management on improvement of general symptoms. However, we could not find sufficient clinical research records to determine their effects of improvement on fatigue and sleep quality. Conclusions: Bojungikgi-tang and its modifications are more effective than non-specific management for improvement of general symptoms in CFS post-treatment.