The objective of this research is to study how rotation speeds affect mechanical properties with friction welding between semi-solid metal 7075 aluminum alloys and semi-solid metal 356 aluminum alloys. The factor of interest is rotation speeds with different conditions at 800 1000 1200 1400 and 1600 rpm respectively. 1.8 millimeter for burn of length 30 seconds for welding time and clockwise rotation are set as a control constant condition for the entire experiment. After friction welding we found that different rotation speeds significantly affected mechanical properties of these alloys. At rotation speed 1400 rpm the maximum tensile strength is 122.24 MPa and the maximum hardness in welded zone is 140.5 HV. The microstructure size is 2.250 µm long and 2.144 µm wide. Its size in welded zone is practically small because of friction force. Moreover this friction force causes the mixture of MgZn2 and Mg2Si in welded zone.

The purposes of this research were to study sexual risk behavior among adolescent and to explore factors affecting sexual risk behavior among adolescent with early sexual intercourse. Research sample was 396 Mathayom Suksa 1 students (lower-secondary students) in secondary schools under the Jurisdiction of the Office of Basic Education Commission Bangkok which was obtained by multi-stage sampling. Data were collected by questionnaire. Data were analyzed by frequency percentage mean standard deviation independent t-test One Way ANOVA Multiple Comparison and Pearson Product Moment Correlation Coefficientsoftware.The result of the study on sexual risk behavior among adolescent with early sexual intercourse was found at the low level. For the factors affecting sexual risk behavior among adolescent with early sexual intercourse they were found that the personal factor including gender parents marital status family type family accommodation and self-sexual acquisition influenced sexual risk behavior among adolescent with early sexual intercourse at the low level. The attitude factor including they were found that the personal factor including sexual values and attitudes toward opposite sex influenced the sexual risk behavior at the high level. The family factor including family raising family sexual communication and supporting of the association of the opposite sex influenced sexual risk behavior among adolescent with early sexual intercourse at the low level. The social factor including friends were found the low-level sexual risk behavior while low-level sexual knowledge acquisition from schools influenced the high-level of sexual risk behavior and sexual content in the media influenced the moderate-levelsexual risk behavior.For the research hypothesis results of the comparison of the personal factor and the social factor toward sexual risk behavior among adolescent with early sexual intercourse it was found that the there was significantly difference forthe personal factor including gender family accommodation and self-sexual acquisition. However there were not significantly different for the parents’ marital status and family type. There was significantly difference for the family factor including family raising family sexual communication and supporting of the association of the opposite sex.The result of the difference between the personal factor and the social factor toward sexual risk behavior among adolescent with early sexual intercourse was found that there was significantly difference for the personal factor including gender family accommodation and self-sexual acquisition. The result of the difference between the attitude factorand the social factor toward sexual risk behavior among adolescent with early sexual intercourse was found that the attitude factor including sex value and attitude toward opposite sex had negative correlation with sexual risk behavior among adolescent with early sexual intercourse at statistical significance. The social factor including friend and sexual content in the media had positive correlation with sexual risk behavior among adolescent with early sexual intercourse at statistical significance. While sexual knowledge acquisition from school did not have the correlation.

Quantitative research synthesis employed statistical methods to synthesize several research papers which were identical in terms of research problems Meta-Analysis in order to discover a standard index that was able to synthesize the aforementioned research papers and to measure the quantifiable effects of manipulated variable on the dependent variable. Regarding this article the author presented and explained Longford’s estimation of effect size which is one of the most efficient and recent estimations. The study proved the background and functional model of the estimator of effect size. In addition the calculation examples following the estimator of Longford’s effect size were demonstrated by meta-analysis.

The objectives of this research were (1) To study the influence of supervisor’s transformational leadership and organizational justice on job satisfaction of employees of BAAC head office; (2) To study the influence of supervisor’s transformational leadership organizational justice and job satisfaction on organizational commitment of employees of BAAC head office. (3) To validate the causal relationship model of supervisor’s transformational leadership and organizational justice on job satisfaction and the organizational commitment of employees of BAAC head office with empirical data. The variables in this investigation consisted of the following: supervisor’s transformational leadership and organizational justice consist as the independent variables; job satisfaction as mediating variable; and organizational commitment as dependent variable. The researcher used quantitative methods which involved empirical research. The instrument of research was a questionnaire used to collect data from 399 employees from BAAC head office. The statistics used in data analysis were frequency mean percentage and structural equation model analysis. It was found that the model was consistent with the empirical data. Goodness of fit measures were found to be Chi-square (2) = 122.230; Degree of freedom = 150; p-value = 0.952; Relative Chi-square (2/df) = 0.815; Goodness of Fit Index (GFI) = 0.980; Adjusted Goodness of Fit Index (AGFI) = 0.938; Comparative Fit Index (CFI) = 1.000; Standardized Root Mean Square Residual (SRMR) = 0.020 and Root Mean Square Error of Approximation (RMSEA) = 0.000. It was also found that: 1. Supervisor’s transformational leadership had positive and direct influence on employee’s job satisfaction. 2. Supervisor’s transformational leadership had positive and direct influence on organizational commitment. 3. Organizational justice in the dimension of distributive justice had positive and direct influence on job satisfaction. 4. Organizational justice in the dimension procedural justice had positive and direct influence on job satisfaction. 5. Organizational justice in the dimension of distributive justice had positive and direct influence on organizational commitment. 6. Job satisfaction had positive and direct influence on organizational commitment. Based on these findings the researcher recommends that BAAC head office more fully focus on supervisor’s transformational leadership organizational justice in the dimensions of distributive justice and procedural justice to deepen the job satisfaction and organizational commitment.

The objectives of this research were (1) To study the influence of the service quality which consisted of the dimensions of tangible reliability responsiveness assurance and empathy on customer trust; (2) To study the influence of the service quality and customer trust on customer satisfaction; (3) To study the influence of customer trust and satisfaction on the positive word of mouth; (4) To study the influence of customer trust and satisfaction on customer revisit and (5) To validate the causal relationship model of the influence of service quality on trust customer satisfaction customer positive word of mouth and revisit of Rama II Hospital with empirical data. The variables in this investigation consisted of the following; service quality which consisted of the dimensions of (1) tangible; (2) reliability (3) responsiveness (4) assurance and (5) empathy as the independent variable; customer trust and satisfaction as mediating variables and customer positive word of mouth and revisit as dependent variables.