• Title/Summary/Keyword: Regression Testing

Search Result 702, Processing Time 0.027 seconds

A Validation Study on the Mediating Effect of Parental Support on the Relationship Between Adolescents' Experiences of Discrimination and Depression

  • Chun-Ok Jang
    • International Journal of Advanced Culture Technology
    • /
    • v.12 no.2
    • /
    • pp.360-367
    • /
    • 2024
  • The purpose of this study was to examine the role of parental support in mitigating the impact of discrimination experiences on depression among children and adolescents. This focus was based on the premise that experiences of discrimination can negatively affect peer relationships as well as behavioral and emotional development in youths who spend a significant amount of time with their peers at school. We aimed to explore the mediating role of parental support and to present policy and practical recommendations from a social welfare perspective. For this purpose, data from the "2020 Survey on the Human Rights of Children and Adolescents" was utilized, involving 9,000 students ranging from 4th to 6th grade in elementary school, grade in middle school, and grade in high school from across the country. The study was conducted targeting these groups. For research analysis, frequency analysis using SPSS 26.0 was employed to calculate the general characteristics of the study subjects and the reliability coefficient of the testing tool. And regression analysis was conducted to verify the mediating effect of parental support on the impact of discrimination experiences on depression. The analysis revealed that there were 4,473 males (51.9%) and 4,150 females (48.1%), and that experiences of discrimination had a negative effect on depression (B=311, P<0.001). It was found that the more frequent the experiences of discrimination, the higher the level of depression, and the more a youth experienced discrimination, the greater the psychological depression they endured.

Correlation of rebound hammer and ultrasonic pulse velocity methods for instant and additive-enhanced concrete

  • Yudhistira J.U. Mangasi;Nadhifah K. Kirana;Jessica Sjah;Nuraziz Handika;Eric Vincens
    • Structural Monitoring and Maintenance
    • /
    • v.11 no.1
    • /
    • pp.41-55
    • /
    • 2024
  • This study aims to determine the characteristics of concrete as identified by Rebound Hammer and Ultrasonic Pulse Velocity (UPV) tests, focusing particularly on their efficacy in estimating compressive strength of concrete material. The study involved three concrete samples designed to achieve a target strength of 29 MPa, comprising normal concrete, instant concrete, and concrete with additives. These were cast into cube specimens measuring 150×150×150 mm. Compressive strength values were determined through both destructive and non-destructive testing on the cubic specimens. As a result, the non-destructive methods yielded varying outcomes for each correlation approach, influenced by the differing constituent materials in the tested concretes. However, normal concrete consistently showed the most reliable correlation, followed by concrete with additives, and lastly, instant concrete. The study found that combining Rebound Hammer and UPV tests enhances the prediction accuracy of compressive strength of concrete. This synergy was quantified through multivariate regression, considering UPV, rebound number, and actual compressive strength. The findings also suggest a more significant influence of the Rebound Hammer measurements on predicting compressive strength for BN and BA, whereas UPV and RN had a similar impact on predicting BI compressive strength.

Distribution Strategies for Food Safety in the Foodservice Industry: Microbial Contamination of Beverages and Cakes

  • Yunseon CHOE;Soyeon YEO;Seungjun LEE;Jinkyung CHOI
    • Journal of Distribution Science
    • /
    • v.22 no.10
    • /
    • pp.103-110
    • /
    • 2024
  • Purpose: This study investigated the microbial status of beverages and desserts containing strawberries sold at coffee outlets in Busan, South Korea. The study sought to identify differencesin types of foodservice management and microbial status of beverages and desserts. Research design and methodology: This study compared microbial status between franchised and single-unit outlets via microbial laboratory tests. In addition, impact of risk factors on microbial status were investigated. We analyzed the data using independent t-tests and chi-square tests. In order to measure the impact of risk factors on microbial status, multiple regression was run. We expected franchised outlets to be more likely to apply food safety practices than single-unit outlets. The principal results: Results of microbial testing showed that franchised outlets had a higher microbial status than single-unit outlets. The results showed that franchise outlets were more inclined to adhere to food safety practices than single-unit outlets when it comes to total number of bacteria however for coliform group results showed otherwise. Major conclusions: These study results suggest that a standard food safety and sanitation manual for coffee outlets is needed, especially for single-unit coffee outlets. The current inspection items should be revised accordingly to ensure customer safety.

Evaluation of direct tensile strength for ultra-high-performance concrete using machine learning algorithms

  • Sanghee Kim;Woo-Young Lim
    • Computers and Concrete
    • /
    • v.34 no.3
    • /
    • pp.367-378
    • /
    • 2024
  • This study evaluates the direct tensile strength of ultra-high-performance concrete (UHPC) using tests. A total of 45 dogbone-shaped specimens are tested, with the test variables being the fiber volume fraction and notch length. The test results showed that the material properties of UHPC were largely dependent on the fiber volume fraction and compressive strength. When steel fibers with more than 1% fiber volume fraction are mixed in the manufacturing of UHPC, the tensile strength can be more than twice that of plain UHPC. In addition, the incorporation of steel fibers enabled the significant improvement of the initial cracking strength. However, the effect of the notch length on the tensile behavior was insignificant. An assessment of the direct tensile strength is conducted using machine-learning algorithms (ML). For evaluation of the direct tensile strength of UHPC using ML, a total of 98 test data, including 53 data from other research works and 45 data from this experimental program, were collected. In total, 67 data with a 70% confidence interval on a normal distribution curve were selected, with 47 data among 67 used for ML training and 20 data used for ML testing. As a result, the machine-learning algorithm with a steel fiber volume fraction predicted that the tensile strength has an average of 0.98 and the lowest values of regression evaluation metrics among analytical and ML-based models. It is considered that an ML-based model can help to predict a more accurate tensile strength of UHPC.

Testing the Relationship between Person-Organizational Value Fit and Performance (개인-조직가치 부합수준과 성과관계 검증)

  • Park, Yang-Kyu;Yeo, Sung-Chil
    • The Korean Journal of Applied Statistics
    • /
    • v.24 no.2
    • /
    • pp.411-424
    • /
    • 2011
  • The studies of congruence in organizational research have explored the concepts such as person-job fit person-organization fit, or person-environment fit. The relevant studies dealt with the fit level as an important influencing factor on the performance. In particular, researchers have agreed that employees can be motivated by the high level fit of person-organization. However, few research developing an alternative methodological approach has been done. For the purpose mentioned above the statistics like D, |D| or $D^2$ and the Q values such as Q(the correlation between two sets of interval measures) or $Q_r$(the correlation between two rankings) have been conventionally adopted in spite of numerous methodological problems. In general, these traditional indices such as difference scores, or Q values, are nondirectional and add an extra weight to differences of lager magnitude. Therefore, Edwards (1993) introduced the polynomial regression and the response surface analysis to overcome flaws with conventional approaches. However, the method-ological approaches did not reflect the profile characteristics of person-organizational value fit and wouldn't be a proper solution for the fit level of person-organization value maximizing performance. Hence, this paper investigates alternative methodological approaches, the multivariate polynomial regression and the multiple response surface analysis, to avoid the problems issued from conventional ways.

Correlations Between the Physical Properties and Compression Index of KwangYang Clay (광양점토의 물리적 특성과 압축지수의 상관성)

  • Bae, Wooseok;Kim, Jongwoo
    • Journal of the Korean GEO-environmental Society
    • /
    • v.10 no.7
    • /
    • pp.7-14
    • /
    • 2009
  • The correlation equation empirically proposed to obtain compression indexes has been proposed to conveniently obtain the value using the soil parameter that can be obtained through simple tests when the number of time of consolidation testing is low or the distribution is large but most of the analyzed regions are limited to certain regions abroad or in the country and multiple data were integrated for use in many cases, thus it is not very reasonable to apply it. Therefore, to establish a new design method considering the uncertainty of the ground, it was selected the Kwangyang port area of which the data have been collected recently thus are relatively more reliable as the subject region of the study in order to maximally reduce the uncertainty of test data. After performing the verification of the normality of the consolidation test data obtained from the selected region and the transformation of variables, a prediction formula was proposed through the regression model with the transformed variables and the proposed regression model with transformed variables was compared with existing empirical equations to verify the suitability of the proposed model formula. After analyzing, it was confirmed that the coefficient of determination was increased after the Box-Cox variable transformation, thus the explanatory power was being enhanced and through the root-mean-square-error method, it was confirmed that the proposed model formula showed the most closed value to the test value.

  • PDF

The Effect of female Hormone on Knee Joint Laxity (여성 호르몬이 무릎의 느슨함(laxity)에 미치는 영향)

  • Park, Sang-Kyoon
    • Korean Journal of Applied Biomechanics
    • /
    • v.19 no.1
    • /
    • pp.99-106
    • /
    • 2009
  • The purpose of this study was to determine whether hormone levels change knee laxity in healthy females. Twenty three healthy females were recruited for the study. Serum estradiol and progesterone levels were recorded three times during the subjects' menstrual cycles. The first measurements were taken between day 3 and 7 of the follicular phase and the second data collection coincided with ovulation, 24 to 48 hours after the estrogen surge detected by an ovulation predictor kits. Based on a 28 day cycle, the third data collection occurred approximately 7 days later during the luteal phase. Knee joint laxity was recorded at the same intervals with a KT 2000 arthometer. Hormone levels and phases were compared to passive knee joint laxity with multiple regression analysis. Estradiol and progesterone levels differed significantly across the three tests. Knee joint laxity increased during ovulation. Based on a multiple regression analysis, estradiol and progesterone levels predicts 77.9% to 80.9% of the laxity at 20lb and 30lb loads. An antagonistic relationship between estradiol and progesterone was found when testing for knee laxity. Serum hormone levels have moderate power in predicting knee joint laxity. Individual hormonal profiling in female athletes would allow researchers to access the structural properties of the ACL, such as the laxity which may provide beneficial information to understand female ACL injury mechanism in sports activity.

A Study of Parallel Test Among Three ADVIA 2120 System (3대의 ADVIA 2120 System 평행시험에 대한 연구)

  • Chang, Sang-Wu;Cho, Eun-Hae;Kim, Nam-Yong;Chu, Kyung-Bok;Lee, Suk-Jong;Hong, Sung-No;Oh, Jong-Do
    • Korean Journal of Clinical Laboratory Science
    • /
    • v.38 no.1
    • /
    • pp.16-21
    • /
    • 2006
  • Parallel testing means ordering a number of tests at the same time so abnormalities in any of the tests can be found quickly and used in making the diagnosis. This is a good medical strategy to eliminate diseases and it is relatively inexpensive if all the tests are potential sources of information and performed on the same analyzer. In regression, the equation for the straight line is recast as y = bx + a. This change in terminology leads to confusion. Here a is the y-intercept or constant and b is the coefficient or slope of the line. A few more words of caution about regression - as in all of statistics there are certain assumptions: the x value is a true measure, both X and Y distributions are normal, and homoscedasticity, i.e., the variance of y is the same for each value of x. In this study the linearity classification made by different scientists were always in agreement. Typical examples of curves that were considered linear are presented in Fig. 1-5. Because these automated procedures values were usually within five percent of each other the curvature could be easily detected. The plot of the WBC, RBC, hemoglobin, hematocrit and platelet concentrations from approximately 74.4 to $0{\times}10^3/{\mu}L$ and $80.4-0{\times}10^3/{\mu}L$, $5.6-0{\times}10^6/{\mu}L$ and $6.1-0{\times}1106/{\mu}L$, 18.3-0 g/dL and 19.0-0 g/dL, 54.1-0% and 56.8-0% and 642.0 to $0.03{\times}10^3{\mu}L$ and $754.0-0{\times}10^3/{\mu}L$ on the ADVIA 2120 C Versus and A and B typical of an acceptable linear study as shown in Fig. 1-5. The grand mean of R2, intercept and slope is 0.99898, 0.99459 and 1.54626.

  • PDF

Prediction of Pumping Friction Resistance Coefficient in Pipe Influenced by Concrete Rheology Properties (콘크리트의 레올로지 특성에 따른 펌핑관내 마찰저항계수의 예측에 관한 연구)

  • Kim, Hyung-Rae;Cho, Ho-Kyoo;Kim, Jung-Chul;Lee, Kewn-Chu
    • Journal of the Korea Institute of Building Construction
    • /
    • v.14 no.2
    • /
    • pp.118-126
    • /
    • 2014
  • The establishment of the technology for evaluating friction resistance and pipe pressure and the relation of the fluid characteristics and pumpability of concrete is essential for concrete pumping performance for the rapid construction of super-tall buildings. In this study, a quantitative evaluation of concrete fluid characteristics and surface friction resistance was performed, applying different concrete mix proportions and pumping conditions. To achieve this, we developed a temporary horizontal pumping evaluation system to measure pipe pressure and surface friction characteristics, and performed an experiment to investigate the relations between concrete rheology characteristics and friction resistance in pipe. The experiment found that in terms of the rheology characteristics, plastic viscosity was reduced remarkably after pumping. As well, high regression between the surface friction and pressure gradient was confirmed. This means that it is possible to evaluate the friction resistance between concrete and pipe by means of a pumping system that includes a frictional resistance testing pipe. In addition, high regression between the plastic viscosity of concrete after pumping and friction resistance coefficient was confirmed. Finally, it is considered that pumping pressure can be predicted using the friction resistance coefficient derived in this study, and it has high regression.

A Study on Startups' Dependence on Business Incubation Centers (창업보육서비스에 따른 입주기업의 창업보육센터 의존도에 관한 연구)

  • Park, JaeSung;Lee, Chul;Kim, JaeJon
    • Korean small business review
    • /
    • v.31 no.2
    • /
    • pp.103-120
    • /
    • 2009
  • As business incubation centers (BICs) have been operating for more than 10 years in Korea, many early stage startups tend to use the services provided by the incubating centers. BICs in Korea have accumulated the knowledge and experience in the past ten years and their services have been considerably improved. The business incubating service has three facets : (1) business infrastructure service, (2) direct service, and (3) indirect service. The mission of BICs is to provide the early stage entrepreneurs with the incubating service in a limited period time to help them grow strong enough to survive the fierce competition after graduating from the incubation. However, the incubating services sometimes fail to foster the independence of new startup companies, and raise the dependence of many companies on BICs. Thus, the dependence on BICs is a very important factor to understand the survival of the incubated startup companies after graduation from BICs. The purpose of this study is to identify the main factors that influence the firm's dependence on BICs and to characterize the relationships among the identified factors. The business incubating service is a core construct of this study. It includes various activities and resources, such as offering the physical facilities, legal service, and connecting them with outside organizations. These services are extensive and take various forms. They are provided by BICs directly or indirectly. Past studies have identified various incubating services and classify them in different ways. Based on the past studies, we classify the business incubating service into three categories as mentioned above : (1) business infrastructure support, (2) direct support, and (3) networking support. The business infrastructure support is to provide the essential resources to start the business, such as physical facilities. The direct support is to offer the business resources available in the BICs, such as human, technical, and administrational resources. Finally, the indirect service was to support the resource in the outside of business incubation center. Dependence is generally defined as the degree to which a client firm needs the resources provided by the service provider in order to achieve its goals. Dependence is generated when a firm recognizes the benefits of interacting with its counterpart. Hence, the more positive outcomes a firm derives from its relationship with the partner, the more dependent on the partner the firm must inevitably become. In business incubating, as a resident firm is incubated in longer period, we can predict that her dependence on BICs would be stronger. In order to foster the independence of the incubated firms, BICs have to be able to manipulate the provision of their services to control the firms' dependence on BICs. Based on the above discussion, the research model for relationships between dependence and its affecting factors was developed. We surveyed the companies residing in BICs to test our research model. The instrument of our study was modified, in part, on the basis of previous relevant studies. For the purposes of testing reliability and validity, preliminary testing was conducted with firms that were residing in BICs and incubated by the BICs in the region of Gwangju and Jeonnam. The questionnaire was modified in accordance with the pre-test feedback. We mailed to all of the firms that had been incubated by the BICs with the help of business incubating managers of each BIC. The survey was conducted over a three week period. Gifts (of approximately ₩10,000 value) were offered to all actively participating respondents. The incubating period was reported by the business incubating managers, and it was transformed using natural logarithms. A total of 180 firms participated in the survey. However, we excluded 4 cases due to a lack of consistency using reversed items in the answers of the companies, and 176 cases were used for the analysis. We acknowledge that 176 samples may not be sufficient to conduct regression analyses with 5 research variables in our study. Each variable was measured through multiple items. We conducted an exploratory factor analysis to assess their unidimensionality. In an effort to test the construct validity of the instruments, a principal component factor analysis was conducted with Varimax rotation. The items correspond well to each singular factor, demonstrating a high degree of convergent validity. As the factor loadings for a variable (or factor) are higher than the factor loadings for the other variables, the instrument's discriminant validity is shown to be clear. Each factor was extracted as expected, which explained 70.97, 66.321, and 52.97 percent, respectively, of the total variance each with eigen values greater than 1.000. The internal consistency reliability of the variables was evaluated by computing Cronbach's alphas. The Cronbach's alpha values of the variables, which ranged from 0.717 to 0.950, were all securely over 0.700, which is satisfactory. The reliability and validity of the research variables are all, therefore, considered acceptable. The effects of dependence were assessed using a regression analysis. The Pearson correlations were calculated for the variables, measured by interval or ratio scales. Potential multicollinearity among the antecedents was evaluated prior to the multiple regression analysis, as some of the variables were significantly correlated with others (e.g., direct service and indirect service). Although several variables show the evidence of significant correlations, their tolerance values range between 0.334 and 0.613, thereby demonstrating that multicollinearity is not a likely threat to the parameter estimates. Checking some basic assumptions for the regression analyses, we decided to conduct multiple regression analyses and moderated regression analyses to test the given hypotheses. The results of the regression analyses indicate that the regression model is significant at p < 0.001 (F = 44.260), and that the predictors of the research model explain 42.6 percent of the total variance. Hypotheses 1, 2, and 3 address the relationships between the dependence of the incubated firms and the business incubating services. Business infrastructure service, direct service, and indirect service are all significantly related with dependence (β = 0.300, p < 0.001; β = 0.230, p < 0.001; β = 0.226, p < 0.001), thus supporting Hypotheses 1, 2, and 3. When the incubating period is the moderator and dependence is the dependent variable, the addition of the interaction terms with the antecedents to the regression equation yielded a significant increase in R2 (F change = 2.789, p < 0.05). In particular, direct service and indirect service exert different effects on dependence. Hence, the results support Hypotheses 5 and 6. This study provides several strategies and specific calls to action for BICs, based on our empirical findings. Business infrastructure service has more effect on the firm's dependence than the other two services. The introduction of an additional high charge rate for a graduated but allowed to stay in the BIC is a basic and legitimate condition for the BIC to control the firm's dependence. We detected the differential effects of direct and indirect services on the firm's dependence. The firms with long incubating period are more sensitive to indirect service positively, and more sensitive to direct service negatively, when assessing their levels of dependence. This implies that BICs must develop a strategy on the basis of a firm's incubating period. Last but not least, it would be valuable to discover other important variables that influence the firm's dependence in the future studies. Moreover, future studies to explain the independence of startup companies in BICs would also be valuable.