• Title/Summary/Keyword: Difference-in-differences analysis

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Comparison of OC and EC Measurement Results Determined by Thermal-optical Analysis Protocols (열광학적 분석 프로토콜에 의한 유기탄소와 원소탄소 측정값 비교)

  • Kim, Hyosun;Jung, Jinsang;Lee, Jinhong;Lee, Sangil
    • Journal of Korean Society for Atmospheric Environment
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    • v.31 no.5
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    • pp.449-460
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    • 2015
  • Carbonaceous aerosol is generally classified into OC (organic carbon) and EC (elemental carbon) by thermal optical analysis. Both NIOSH (National institute of occupational safety and health) with high temperature (HighT) and IMPROVE-A (Interagency monitoring of protected visual environments) with low temperature (LowT) protocols are widely used. In this study, both protocols were applied for ambient $PM_{2.5}$ samples (Daejeon, Korea) in order to underpin differences in OC and EC measurements. An excellent agreement between NIOSH and IMPROVE-A protocol was observed for TC (total carbon). However, significant differences between OC and EC appeared and the differences were larger for EC than OC. The main differences between two protocols are temperature profile and charring correction method. For the same charring correction method, HighT_OC was 10% higher than LowT_ OC, while HighT_EC was 15% and 33% lower than LowT_EC for TOT (thermal-optical transmittance) and TOR (thermal-optical reflectance), respectively. This difference may be caused by the temperature of OC4 in He step and possibly difference in POC (pryorilized OC) formation. For the same temperature profile, OC by TOT was about 26% higher than that by TOR. In contrast, EC by TOT was about 50% lower than that by TOR. POC was also dependent on both temperature profile and the charring correction method, showing much distinctive differences for the charring correction method (i.e., POC by TOT to POC by TOR ratio is about 2). This difference might be caused by different characteristics between transmittance and reflectance for monitoring POC formation within filters. Results from this study showed that OC and EC depends on applied analysis protocol as shown other studies. Because of the nature of the thermal optical analysis, it may not be possible to have an absolute standard analysis protocol that is applicable for any ambient $PM_{2.5}$. Nevertheless, in order to provide consistent measurement results for scientists and policy makers, future studies should focus on developing a harmonized standard analysis protocol that is suitable for a specific air domain and minimizes variations in OC and EC measurement results. In addition, future elaborate studies are required to find and understand the causes of the differences.

Evaluating Correlation between Geometrical Relationship and Dose Difference Caused by Respiratory Motion Using Statistical Analysis

  • Shin, Dong-Seok;Kang, Seong-Hee;Kim, Dong-Su;Kim, Tae-Ho;Kim, Kyeong-Hyeon;Cho, Min-Seok;Noh, Yu-Yoon;Yoon, Do-Kun;Suh, Tae Suk
    • Progress in Medical Physics
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    • v.27 no.4
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    • pp.203-212
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    • 2016
  • Dose differences between three-dimensional (3D) and four-dimensional (4D) doses could be varied according to the geometrical relationship between a planning target volume (PTV) and an organ at risk (OAR). The purpose of this study is to evaluate the correlation between the overlap volume histogram (OVH), which quantitatively shows the geometrical relationship between the PTV and OAR, and the dose differences. 4D computed tomography (4DCT) images were acquired for 10 liver cancer patients. Internal target volume-based treatment planning was performed. A 3D dose was calculated on a reference phase (end-exhalation). A 4D dose was accumulated using deformation vector fields between the reference and other phase images of 4DCT from deformable image registration, and dose differences between the 3D and 4D doses were calculated. An OVH between the PTV and selected OAR (duodenum) was calculated and quantified on the basis of specific overlap volumes that corresponded to 10%, 20%, 30%, 40%, and 50% of the OAR volume overlapped with the expanded PTV. Statistical analysis was performed to verify the correlation with the OVH and dose difference for the OAR. The minimum mean dose difference was 0.50 Gy from case 3, and the maximum mean dose difference was 4.96 Gy from case 2. The calculated range of the correlation coefficients between the OVH and dose difference was from -0.720 to -0.712, and the R-square range for regression analysis was from 0.506 to 0.518 (p-value <0.05). However, when the 10% overlap volume was applied in the six cases that had OVH value ${\leq}2$, the average percent mean dose differences were $34.80{\pm}12.42%$. Cases with quantified OVH values of 2 or more had mean dose differences of $29.16{\pm}11.36%$. In conclusion, no significant statistical correlation was found between the OVH and dose differences. However, it was confirmed that a higher difference between the 3D and 4D doses could occur in cases that have smaller OVH value.

The Advertising Effects of Fashion Sexual Appeal Advertising (패션 성적소구광고의 광고효과에 관한 연구)

  • Lee, Seung-Hee
    • Journal of Fashion Business
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    • v.13 no.4
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    • pp.154-162
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    • 2009
  • The purpose of this study was to examine if there are the differences in advertising effects among three fashion sexual advertisements in terms of sexual appeal levels(high/medium/low). Through three pre-tests, three stimuli were chosen for this study. Three hundred female college students in Seoul participated in this study. For data analysis, descriptive statistics, factor analysis, ANOVA analysis, and reliability test were used. The results were as follows: First, from the factor analysis on advertising attitudes, three factors such as emotional, behavioral, and cognitive factors were produced. Second, there were significant differences in three sexual appeal levels among three advertising attitude factors. Third, there was also a significant difference in three sexual appeal levels on brand attitude. Finally, there was not a significant difference in the sexual appeal levels on purchase intention. Based on these results, this study would provide significant and efficient fashion advertising strategies to fashion advertising marketers and advertisement creators as implications.

The Measurement of Physical Properties of Outdoor Exposed Members

  • Kim, Gwang-Chul;Kim, Jun-Ho
    • Journal of the Korean Wood Science and Technology
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    • v.47 no.3
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    • pp.311-323
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    • 2019
  • The number of newly constructed traditional Korean houses, i.e., Hanoks, and light-frame buildings is increasing. However, related research is limited owing to the lack of awareness regarding safety evaluations. Therefore, this study conducted an outdoor exposure test to accurately evaluate wooden constructions. Spruce, pine, and fir (SPF) material was monitored for a year, wherein the SPF material was artificially dried under 18% moisture content, and its physical properties and color differences were measured once a month. Large differences were observed in the material's weight and moisture content, which are indexes sensitive to daily range and rainfall; however, no significant difference was found for other basic properties in the pre and post test results. Herein, $L^*$, $a^*$, and $b^*$ values represent color differences; these values exhibited a general decrease after the test. Such differences were attributed to the loss of lignin in the wood. The color difference value was high between the months of May and July, when the daily range and rainfall significantly fluctuated. Multiple regression analysis was performed on the $a^*$ value (redness indicator), daily range, rainfall, and ultraviolet index. The results indicated that the daily range influenced redness the most. According to the estimated regression equation, the daily range and redness are positively correlated. Based on the results, the types and influence of independent variables on color difference are expected to change as the wood's duration of outdoor exposure and the amount of data obtained both increase.

Sensibility Images of Korean Traditional Chumoni (한국전통주머니에 나타난 감성이미지)

  • 강정현;권영숙
    • Journal of the Korean Society of Costume
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    • v.53 no.4
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    • pp.1-16
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    • 2003
  • The purpose of this study is to investigate the sensibility images of Korean Traditional Chumoni. The detailed methodology of this study is as follows. Selections of stimuli to analyse the sensibility images of Korean Traditional Chumoni were made up of 15 stimuli. The survey has been done for the 15 slide stimuli with semantic differential hi-polar scales which are consist of 23 couples of sensibility words. The subjects were 150 female students majoring in clothing and textile. 150 male students majoring in other department and 150 female students majoring in other department in the twenties between 2001. 3. 30 and 2001. 4. 4. The obtained data were analyzed by factor analysis, cluster analysis. ANOVA. The major finds were as follows. 1. To explain the hierarchy of the sensibility of Korean Traditional Chumoni, two image groups were classified, one is noble and characteristic image the other is splendid and intensive image. Finally it represented noble and splendid image. 2. As result of the factor analysis. 3 factors which are Attraction, Decorativeness, Gravity were found to be constructing factors for the sensibility images of Korean Traditional Chumoni. 3. By cluster analysis, 4 clusters were determined according to Korean Traditional Chumoni. Cluster 1 is splendid. multi-colored and realistic in patteren. Cluster 2 is consist of 'true chumonis' and one-colored. Cluster 3 is modal in pattern. Cluster 4 is simple without any decorations. As to the difference of image of Korean Traditional Chumoni, there were significant differences amang 3 factors by cluster Cluster 1 was found most attractive and grave. Cluster 2 was found most decorative. 4. As to the difference of image of Korean Traditional Chumoni, there were significant differences amang 3 factors by decoration. Gold foil was found most attractive and grave. Embroidery was found most decorative. 5. As to the difference of image of Korean traditional chumoni, there were differences in Decorativeness and Gravity by sex and there were differences in Attraction by major.

Proposal of Research Methodology Using The Measurement of Perception Difference

  • YANG, Hoechang
    • Journal of Wellbeing Management and Applied Psychology
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    • v.2 no.2
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    • pp.39-45
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    • 2019
  • The purpose of this study is to solve the problem of revision or abbreviation of questionnaires based on the previous studies suggested by many existing empirical studies. In addition, this study aims to provide the theoretical basis of the research method which has been variously approached since it presents the methodology that can directly measure the research object. For this purpose, this study proposed a more elaborate analysis method using the differences in perception of individuals who are interested in cognitive research. Specifically, the perception gap(D) can be used as an independent variable, a dependent variable, and a moderating variable. And this study suggested an effective research approach using the measurement of perception difference. The difference of perception suggested that it can be used as a measure to overcome the limitations of existing researches used it as independent variables or mediating variables that measure only one factor of expectation and performance or importance and satisfaction. In addition, it is highly likely that various analyzes on the perception differences, which are the result of measuring target factors for the same person, will be quite effective in the situation where follow-up of respondents is difficult. This study is expected to overcome various limitations reported by empirical studies such as scale utilization problem and follow-up survey difficulty. In future research, it was expected that the limitation of the factor derivation process in the research approach could be complemented by web crawling and text mining of big data analysis.

An Analysis of the Differences in Foodservice Industry Employees Service Orientation Factor (외식업체 종사원의 서비스 지향성 요인에 관한 차이 분석)

  • Kim, Ki-Young;Min, Kye-Hong
    • Culinary science and hospitality research
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    • v.13 no.1 s.32
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    • pp.166-178
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    • 2007
  • A review of literature relating to the research topic and a survey method have been implemented in order to analyze effects of service orientation. For data analysis, a reliability analysis was performed to test the reliability of the construct and a series of an exploratory factor analysis was used for the validity test. The findings of the study were as follows: Classified into sex, service leadership factor and service skill factor showed meaningful difference between groups. Classified with age, service training factor, service leadership factor, service standardization factor, service technology factor, and service compensation factor showed meaningful difference between groups. Classified with scholarship, service compensation factor showed meaningful difference. Classified into working year, employees' discretion factor showed meaningful difference. Classified into work department, service training factor and employees' right factor showed meaningful difference. In addition, classified into monthly average incomes, employees' discretion factor showed meaningful difference.

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A Study on Difference between Korea and China Consumers in importance of Attributes, Shopping Value and Loyalty in Social Commerce (한국과 중국소비자의 소셜커머스 속성의 중요도, 쇼핑가치 및 충성도 차이에 관한 연구)

  • Kim, Moon-Jung
    • Journal of Distribution Science
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    • v.13 no.1
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    • pp.47-55
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    • 2015
  • Purpose - The objective of this study is to verify whether there are differences between Korean and Chinese consumers in the importance of the attributes such as shopping value and loyalty in social commerce. With the purpose of finding out these differences, the following questions are set up as research questions. First, will there be a difference between Korea and China in the importance of attributes of social commerce? Second, will there be a difference between Korean and Chinese consumers in shopping value? Third, will there be a difference between Korean and Chinese consumers in their loyalty? Research design, data, and methodology - The researchers collected data through self-administered questionnaires from Korean and Chinese consumers who had used social commerce within the past six months before answering the questionnaire. First, for social commerce users in Korea, comprising male and female university students in Chungcheong, a questionnaire was circulated. For social commerce users in China, university students within Beijing were surveyed. Responses to 336 questionnaires were used, excluding those with no answers or unreliable answers. Data coding and data cleaning were used. SPSS 18.0 was used. First, exploratory factor analysis is done to verify the validity of testing tools, and Cronbach's α coefficient is used to verify credibility. For factor analysis, the Varimax method is used. To verify the internal consistency reliability of each factor, the Cronbach's α coefficient is used to verify the credibility. Second, a T-test is done to verify differences between Korean and Chinese consumers for the importance of attributes. Third, ANOVA (Analysis of variance) is done to verify differences between Korean and Chinese consumers in shopping value and loyalty. Results - When Korean and Chinese consumers use social commerce, first, the importance of the attributes of social commerce is affected by four factors; playfulness and economic factors are more important to Korean consumers than Chinese consumers. As for informativeness factors, including product information and quality, and buyer comments, there was no confirmed difference between Korean and Chinese consumers. The convenience factor is more important to Chinese consumers than Korean consumers. Second, the factors affecting shopping value for Korean and Chinese consumers were hedonic shopping value and rational shopping value. To see the difference between Korean and Chinese consumers in shopping value factors, a t-test is conducted. As a result, in the rational shopping value factors of social commerce, Korean consumers scored higher than did Chinese consumers. These results were verified to be meaningful through statistics. In the hedonic shopping value factor of social commerce, Korean consumers scored higher than Chinese consumers. These results showed a significant difference. Third, loyalty in social commerce is higher for Chinese consumers than for Korean consumers. However, there is no difference in loyalty depending on sex. Conclusion - These results will hopefully be valuable and used in the future by Korean companies that wish to enter the Chinese social commerce market.

Hairdo Attitude.Hairdo Involvement Importances and Differences Depending on Age (헤어 태도.헤어 관여의 중요도와 연령에 따른 차이)

  • Lee, Hye-Won;Kim, Mi-Young
    • The Research Journal of the Costume Culture
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    • v.15 no.6
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    • pp.917-928
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    • 2007
  • The purposes of this study were to investigate the hairdo attitude and hairdo involvement importances and differences depending on age. For the experimental work, questionnaires for research are prepared and asked to people who are women living in Seoul and Kyoung-Ki Do. They are collected from September to October 2006. 406 questionnaires are used in the analysis. The collected data were 'analyzed by using SPSS 12.0 software with factor analysis, Cronbach's alpha, paired T-test, and T-test. The results of this study were as follows; To analyze differences in the hairdo attitude and the hair involvement depending on different age groups, two groups were identified: one group of women aged $20{\sim}35$, and the other group of those aged $45{\sim}60$. 1. When the hairdo attitude factors were prioritized, orientations toward 'constancy' and 'consciousness of others' were found to be most critical, followed by those toward 'leader's fashion conformity' and 'distinct individuality'. When the hairdo involvement factors were prioritized, 'interests and pleasure in hairdo' were found to be most important, followed by 'symbolic representation', 'risk awareness', 'coordination of hairdo', and 'fashionableness'. 2. When difference in the hairdo attitude was analyzed, a significant difference was shown in orientations toward 'leader's fashion conformity' and 'consciousness of others'. 3. As for the hairdo involvement of the groups, a significant difference was found only in 'coordination of hairdo', signalling that the younger women put more focus on the coordination.

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Purchase Intention of Fashion Goods on Internet Shopping Mall - The Difference to Follow Internet Shopping Mall Utility Actual Condition and the Socioeconomic Variable - (인터넷 쇼핑몰에서 패션상품 구매의도에 관한 연구 - 사회경제적 변수 및 인터넷 쇼핑몰 사용실태에 따른 차이 -)

  • Jung, Jin-Ho;Park, Hea-Ryung
    • The Korean Fashion and Textile Research Journal
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    • v.3 no.3
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    • pp.249-256
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    • 2001
  • This study was to investigate difference across socioeconomic groups in factors of purchase intention of apparel in internet shopping mall and in satisfaction were internet shopping mall. A questionnaire was administered to collage students majoring in fashion design during May of 2001. Data was analyzed by using Factor analysis, T-test, one-way ANOVA, Duncan test, ${\chi}^2$-test. Factor analysis yield three factors of purchase intention, purchase stimulus, convenience and economic and rationality. Significant differences were found across levels of monthly pocket money and types of payment for purchase apparel of internet shopping mall purchase stimulus (factor 1). In convenience and economics (factor 2), differences were also significant across levels of purchase frequency, product price and payment ways of internet sopping mall. Significant difference was identified across sex type and levels of product price purchased in internet shopping mall (factor 3). Regarding internet shopping mall satisfaction, differences were significant across levels monthly pocket money and apparel purchase frequency of in internet shopping mall.

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