• Title/Summary/Keyword: Consistency test

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Soil Characteristics according to the Geological Condition of Soil Slopes in Landslide Area (산사태지역 토층사면의 지질조건별 토질특성)

  • Kim, Kyeong-Su
    • The Journal of Engineering Geology
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    • v.16 no.4 s.50
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    • pp.359-371
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    • 2006
  • In this study, the soil characteristics are analyzed using the result of various soil tests as an object of the soil layer of natural slopes in landslides areas composed with gneiss, granite, and the tertiary sedimentary rock. To investigate the soil characteristics according to landslide and non landslide areas, soils are sampled from Jangheung, Sangju and Pohang. The landslides at three areas are occurred due to heavy rainfall in same time. The geology of Jangheung area, Sangju area and Pohang area is gneiss, granite, and the tertiary sedimentary rock, respectively. On the basis of the landslide data and the result of soil test, the soil characteristics at the landslide area and the differentiation between landslide area and non landslide area are analyzed. However soil characteristics have a little differentiation to geological condition, the uniformity coefficient and the coefficient of gradation of soils at the landslide area is larger than those of soils at the non landslide area. Also, the proportion of fine particle of soils at the landslide area is higher. The plastic limit of soils sampled from the granite and the sedimentary rock regions is larger than that sampled from the gneiss region. However the liquid limit is irrelevant to the geological condition. Also, the consistency of soils at the landslide area is smaller. The natural moisture content of soils in the sedimentary rock regions is larger than that of the granite and gneiss. It is mainly influenced by mineral composition, soil layer structure, weathering condition, and so on. The soils sampled from landslide area have higher porosity and lower density than those from non landslide area. It means that the soils of landslide area have poor particle size distribution and loose density. Therefore, the terrain slope with poor distribution and loose density is vulnerable to occur in landslides. Also, landslides are occurred in the terrain slope with high permeability. The permeability is mainly influenced by the soil characteristics such as particle size distribution, porosity, particle structure, and the geological origins such as weathering, sedimentary environment. Meanwhile, the shear strength of soils is little difference according to the geological condition. But, the internal friction angle of soils sampled from the landslide area is lower than that of soils from the non landslide area. Therefore, the terrain slope with low internal friction angle is more vulnerable to the landslide.

A Development and Validation Study of the Web-based Korean Version of the Eating Disorder Diagnostic Scale DSM-5 (웹 기반 한국판 섭식장애진단척도 DSM-5의 개발 및 타당화 연구)

  • Lee, Hye Rin;Kwag, Kyung Hwa;Lee, You Kyung;Han, Soo Wan;Kim, Youl-Ri
    • Korean Journal of Psychosomatic Medicine
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    • v.28 no.2
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    • pp.185-193
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    • 2020
  • Objectives : The aim of this study was to develop and to verify the Korean version of the Eating Disorder Diagnosis Scale DSM-5 (K-EDDS) as a web-based diagnostic system, which enables rapid diagnosis of patients for early intervention. Methods : A total of 119 persons participated in the study, including patients with eating disorders (n=38) and college students (n=81). Along with the paper-and-pencil SCOFF, all participants completed the web-based K-EDDS, the Eating Disorder Examination-Questionaire (EDE-Q), and the Clinical Impairment Assessment Questionnaire (CIA). The semi-structured interview using the Eating Disorder Examination Interview (EDE) was conducted for participants with two or more SCOFF scores. Within two weeks, the web-based K-EDDS, the EDE-Q, and the CIA were re-tested. Results : In the exploratory factor analysis, four factors were extracted : body dissatisfaction, binge behaviors, binge frequency and compensatory behaviors. The four subscales of the web-based K-EDDS had significant correlation with each of the four subscales of the EDE-Q. The internal consistency of the web-based K-EDDS was highly satisfactory (Cronbach's alpha=0.93). The diagnostic agreement between the web-based K-EDDS and the EDE was excellent (96.83%), and the web-based K-EDDS's test-retest diagnostic agreement was fairly good (92.86%). The web-based K-EDDS and the CIA also showed significant differences between patients and general population, supporting discriminant validity. Conclusions : This study suggested that the web-based K-EDDS is a valid tool for assisting diagnosis of eating disorders based on DSM-5 in clinical and research fields.

A Longitudinal Validation Study of the Korean Version of PCL-5(Post-traumatic Stress Disorder Checklist for DSM-5) (PCL-5(DSM-5 기준 외상 후 스트레스 장애 체크리스트) 한국판 종단 타당화 연구)

  • Lee, DongHun;Lee, DeokHee;Kim, SungHyun;Jung, DaSong
    • Korean Journal of Culture and Social Issue
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    • v.28 no.2
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    • pp.187-217
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    • 2022
  • The aim of this study is to examine the psychometric properties of the Korean version of the Post-traumatic Stress Disorder Checklist for DSM-5(PCL-5). For this purpose, online surveys were conducted for two times with a one year interval using the data from 1,077 Korean adults at time 1, and 563 Korean adults at time 2. First, from the result of the confirmatory factor analysis, comparing the model fit of the 1, 4, 6, and 7-factor model, the 4, 6, and 7-factor model showed a acceptable fit, and the best fit was seen in the order of the 7, 6, 4-factor model. Second, the internal consistency, omega coefficient, construct validity, average variance extracted, and test-retest reliability results were all satisfactory.. Third, a correlation analysis with the K-PC-PTSD-5 and the sub-factors of BSI-18 was conducted to check the validity of the Korean Version of PCL-5. As a result, a positive correlation was seen with both K-PC-PTSD-5 and BSI-18. Fourth, a hierarchical multiple regression was performed to examine whether the Korean Version of PCL-5 predicts future PTSD, depression, anxiety, and somatization. As a result, the Korean Version of PCL-5 measured at time 1 significantly predicted PTSD, depression, anxiety, and somatization symptoms at time 2. Fifth, by analyzing the ROC curve, the discriminant power of PCL-5 for screening PTSD symptom groups was confirmed, and the best cut-off score was suggested. As a result of the longitudinal validation of Korean version of PCL-5, it was found that this scale is a reliable and valid measure for Korean adults. By looking into the predictive validity of the scale, it was found that the Korean version of PCL-5 can predict not only PTSD symptoms but also PTSD-related symptoms such as depression, anxiety, and somatization. Also, this study differs from previous validation studies measuring PTSD symptoms in that it suggested a cut-off score to help differentiate PTSD symptom groups.

Diversification of Rice Quality for Processing. Physicochemical Characteristics and Inheritance of Floury Endosperm Mutants (특수 가공용 미질개발 : 분상질배유 돌연변이 계통의 이화학적특성과 유전)

  • Kim, Kwang-Ho;Koh, Hee-Jong;Lee, Jang-Hoon;Park, Sun-Zik;Heu, Mun-Hue
    • KOREAN JOURNAL OF CROP SCIENCE
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    • v.38 no.3
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    • pp.264-274
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    • 1993
  • This study was carried out to assess the agronomic characters and physicochemical properties of floury and chalky-endosperm mutant lines induced by chemical mutagen treatment to rice varieties, Hwacheongbyeo and IR24. Linkage analysis of a floury-endosperm gene was carried out using linkage testers. The grain size of brown rice of the mutants was smaller than that of the original varieties. The l, 000-grain and 1$\ell$ weight were lighter in the mutants compared with those in the original varieties. The compound starch granules in the endosperm cell of the mutants showed a loosely-packed crystalline structure. Amylose contents in mutants ranged from 16.9 to 28.5%. Crude protein contents of the mutants were not significantly different from the original rice variety, Hwacheongbyeo, but white core mutant(line 47106) derived from IR24 showed higher protein(l1.32%) compared with IR24(8.30%). The mutants showed slightly harder gel characteristics, and much lower viscosity in Amylograph than original varieties. Steamed rice-cakes from mutant lines showed greater volume than those from original varieties. During the process of alcohol fermentation, Brix in the mutants(especially floury mutants) decreased faster and the alcohol production after 10-day fermentation was much greater in the mutants than in the original varieties. Three different gene loci for floury endosperm characteristics were identified from the allelism test among mutant lines, and the genes were tentatively symbolized as flo-a, flo-b and flo-c, respectively. A floury gene, flo-a, was linked with lg(liguleless) gene in the linkage group N, with R.V. 5.76$\pm$1.72%.

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Development and Validation of Classroom Problem Behavior Scale - Elementary School Version(CPBS-E) (초등학생 문제행동선별척도: 교사용(CPBS-E)의 개발과 타당화)

  • Song, Wonyoung;Chang, Eun Jin;Choi, Gayoung;Choi, Jae Gwang;ChoBlair, Kwang-Sun;Won, Sung-Doo;Han, Miryeung
    • Korean Journal of School Psychology
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    • v.16 no.3
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    • pp.433-451
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    • 2019
  • This study aimed to develop and validate the Classroom Problem Behavior Scale - Elementary School Version (CPBS-E) measure which is unique to classroom problem behavior exhibited by Korean elementary school students. The focus was on developing a universal screening instrument designed to identify and provide intervention to students who are at-risk for severe social-emotional and behavioral problems. Items were initially drawn from the literature, interviews with elementary school teachers, common office discipline referral measures used in U.S. elementary schools, penalty point systems used in Korean schools, 'Green Mileage', and the Inventory of Emotional and Behavioral Traits. The content validity of the initially developed items was assessed by six classroom and subject teachers, which resulted in the development of a preliminary scale consisting of 63 two-dimensional items (i.e., Within Classroom Problem Behavior and Outside of Classroom Problem Behavior), each of which consisted of 3 to 4 factors. The Within Classroom Problem Behavior dimension consisted of 4 subscales (not being prepared for class, class disruption, aggression, and withdrawn) and the Outside of Classroom Problem Behavior dimension consisted of 3 subscales (rule-violation, aggression, and withdrawn). The CPBS-E was pilot tested on a sample of 154 elementary school students, which resulted in reducing the scale to 23 items. Following the scale revision, the CPBS-E was validated on a sample population of 209 elementary school students. The validation results indicated that the two-dimensional CPBS-E scale of classroom problem behavior was a reliable and valid measure. The test-retest reliability was stable at above .80 in most of the subscales. The CPBS-E measure demonstrated high internal consistency of .76-.94. In examining the criterion validity, the scale's correlation with the Teacher Observation of Classroom Adaptation-Checklist (TOCA-C) was high and the aggression and withdrawn subscales of the CPBS-E demonstrated high correlations with externalization and internalization, respectively, of the Child Behavior Checklist - Teacher Report Form CBCL-TRF). In addition, the factor structure of the CPBS-E scale was examined using the structural equation model and found to be acceptable. The results are discussed in relation to implications, contributions to the field, and limitations.

Developing a Tool to Assess Competency to Consent to Treatment in the Mentally Ill Patient: Reliability and Validity (정신장애인의 치료동의능력 평가 도구 개발 : 신뢰도와 타당화)

  • Seo, Mi-Kyoung;Rhee, MinKyu;Kim, Seung-Hyun;Cho, Sung-Nam;Ko, Young-hun;Lee, Hyuk;Lee, Moon-Soo
    • Korean Journal of Health Psychology
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    • v.14 no.3
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    • pp.579-596
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    • 2009
  • This study aimed to develop the Korean tool of competency to consent to psychiatric treatment and to analyze the reliability and validity of this tool. Also the developed tool's efficiency in determining whether a patient possesses treatment consent competence was checked using the Receiver Operating Characteristic curve and the relevant indices. A total of 193 patients with mental illness, who were hospitalized in a mental hospital or were in community mental health center, participated in this study. We administered a questionnaire consisting of 14 questions concerning understanding, appreciation, reasoning ability, and expression of a choice to the subjects. To investigate the validity of the tool, we conducted the K-MMSE, insight test, estimated IQ, and BPRS. The tool's reliability and usefulness were examined via Cronbach's alpha, ICC, and ROC analysis, and criterion related validation was performed. This tool showed that internal consistency and agreement between raters was relatively high(ICC .80~.98, Cronbach's alpha .56~.83)and the confirmatory factor analysis for constructive validation showed that the tool was valid. Also, estimated IQ, and MMSE were significantly correlated to understanding, appreciation, expression of a choice, and reasoning ability. However, the BPRS did not show significant correlation with any subcompetences. In ROC analysis, full scale cutoff score 18.5 was suggested. Subscale cutoff scores were understanding 4.5, appreciation 8.5, reasoning ability 3.5, and expression of a choice 0.5. These results suggest that this assessment tool is reliable, valid and efficient diagnostically. Finally, limitations and implications of this study were discussed.

The Research on Online Game Hedonic Experience - Focusing on Moderate Effect of Perceived Complexity - (온라인 게임에서의 쾌락적 경험에 관한 연구 - 지각된 복잡성의 조절효과를 중심으로 -)

  • Lee, Jong-Ho;Jung, Yun-Hee
    • Journal of Global Scholars of Marketing Science
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    • v.18 no.2
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    • pp.147-187
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    • 2008
  • Online game researchers focus on the flow and factors influencing flow. Flow is conceptualized as an optimal experience state and useful explaining game experience in online. Many game studies focused on the customer loyalty and flow in playing online game, In showing specific game experience, however, it doesn't examine multidimensional experience process. Flow is not construct which show absorbing process, but construct which show absorbing result. Hence, Flow is not adequate to examine multidimensional experience of games. Online game is included in hedonic consumption. Hedonic consumption is a relatively new field of study in consumer research and it explores the consumption experience as a experiential view(Hirschman and Holbrook 1982). Hedonic consumption explores the consumption experience not as an information processing event but from a phenomenological of experiential view, which is a primarily subjective state. It includes various playful leisure activities, sensory pleasures, daydreams, esthetic enjoyment, and emotional responses. In online game experience, therefore, it is right to access through a experiential view of hedonic consumption. The objective of this paper was to make up for lacks in our understanding of online game experience by developing a framework for better insight into the hedonic experience of online game. We developed this framework by integrating and extending existing research in marketing, online game and hedonic responses. We then discussed several expectations for this framework. We concluded by discussing the results of this study, providing general recommendation and directions for future research. In hedonic response research, Lacher's research(1994)and Jongho lee and Yunhee Jung' research (2005;2006) has served as a fundamental starting point of our research. A common element in this extended research is the repeated identification of the four hedonic responses: sensory response, imaginal response, emotional response, analytic response. The validity of these four constructs finds in research of music(Lacher 1994) and movie(Jongho lee and Yunhee Jung' research 2005;2006). But, previous research on hedonic response didn't show that constructs of hedonic response have cause-effect relation. Also, although hedonic response enable to different by stimulus properties. effects of stimulus properties is not showed. To fill this gap, while largely based on Lacher(1994)' research and Jongho Lee and Yunhee Jung(2005, 2006)' research, we made several important adaptation with the primary goal of bringing the model into online game and compensating lacks of previous research. We maintained the same construct proposed by Lacher et al.(1994), with four constructs of hedonic response:sensory response, imaginal response, emotional response, analytical response. In this study, the sensory response is typified by some physical movement(Yingling 1962), the imaginal response is typified by images, memories, or situations that game evokes(Myers 1914), and the emotional response represents the feelings one experiences when playing game, such as pleasure, arousal, dominance, finally, the analytical response is that game player engaged in cognition seeking while playing game(Myers 1912). However, this paper has several important differences. We attempted to suggest multi-dimensional experience process in online game and cause-effect relation among hedonic responses. Also, We investigated moderate effects of perceived complexity. Previous studies about hedonic responses didn't show influences of stimulus properties. According to Berlyne's theory(1960, 1974) of aesthetic response, perceived complexity is a important construct because it effects pleasure. Pleasure in response to an object will increase with increased complexity, to an optimal level. After that, with increased complexity, pleasure begins with a linearly increasing line for complexity. Therefore, We expected this perceived complexity will influence hedonic response in game experience. We discussed the rationale for these suggested changes, the assumptions of the resulting framework, and developed some expectations based on its application in Online game context. In the first stage of methodology, questions were developed to measure the constructs. We constructed a survey measuring our theoretical constructs based on a combination of sources, including Yingling(1962), Hargreaves(1962), Lacher (1994), Jongho Lee and Yunhee Jung(2005, 2006), Mehrabian and Russell(1974), Pucely et al(1987). Based on comments received in the pretest, we made several revisions to arrive at our final survey. We investigated the proposed framework through a convenience sample, where participation in a self-report survey was solicited from various respondents having different knowledges. All respondents participated to different degrees, in these habitually practiced activities and received no compensation for their participation. Questionnaires were distributed to graduates and we used 381 completed questionnaires to analysis. The sample consisted of more men(n=225) than women(n=156). In measure, the study used multi-item scales based previous study. We analyze the data using structural equation modeling(LISREL-VIII; Joreskog and Sorbom 1993). First, we used the entire sample(n=381) to refine the measures and test their convergent and discriminant validity. The evidence from both the factor analysis and the analysis of reliability provides support that the scales exhibit internal consistency and construct validity. Second, we test the hypothesized structural model. And, we divided the sample into two different complexity group and analyze the hypothesized structural model of each group. The analysis suggest that hedonic response plays different roles from hypothesized in our study. The results indicate that hedonic response-sensory response, imaginal response, emotional response, analytical response- are related positively to respondents' level of game satisfaction. And game satisfaction is related to higher levels of game loyalty. Additionally, we found that perceived complexity is important to online game experience. Our results suggest that importance of each hedonic response different by perceived game complexity. Understanding the role of perceived complexity in hedonic response enables to have a better understanding of underlying mechanisms at game experience. If game has high complexity, analytical response become important response. So game producers or marketers have to consider more cognitive stimulus. Controversy, if game has low complexity, sensorial response respectively become important. Finally, we discussed several limitations of our study and suggested directions for future research. we concluded with a discussion of managerial implications. Our study provides managers with a basis for game strategies.

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The Usefulness of Product Display of Online Store by the Product Type of Usage Situation - Focusing on the moderate effect of the product portability - (사용상황별 제품유형에 따른 온라인 점포 제품디스플레이의 유용성 - 제품 휴대성의 조절효과를 중심으로 -)

  • Lee, Dong-Il;Choi, Seung-Hoon
    • Journal of Distribution Research
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    • v.16 no.2
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    • pp.1-24
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    • 2011
  • 1. Introduction: Contrast to the offline purchasing environment, online store cannot offer the sense of touch or direct visual information of its product to the consumers. So the builder of the online shopping mall should provide more concrete and detailed product information(Kim 2008), and Alba (1997) also predicted that the quality of the offered information is determined by the post-purchase consumer satisfaction. In practice, many fashion and apparel online shopping malls offer the picture information with the product on the real person model to enhance the usefulness of product information. On the other virtual product experience has been suggested to the ways of overcoming the online consumers' limited perceptual capability (Jiang & Benbasat 2005). However, the adoption and the facilitation of the virtual reality tools requires high investment and technical specialty compared to the text/picture product information offerings (Shaffer 2006). This could make the entry barrier to the online shopping to the small retailers and sometimes it could be demanding high level of consumers' perceptual efforts. So the expensive technological solution could affects negatively to the consumer decision making processes. Nevertheless, most of the previous research on the online product information provision suggests the VR be the more effective tools. 2. Research Model and Hypothesis: Presented in

    , research model suggests VR effect could be moderated by the product types by the usage situations. Product types could be defined as the portable product and installed product, and the information offering type as still picture of the product, picture of the product with the real-person model and VR. 3. Methods and Results: 3.1. Experimental design and measured variables We designed the 2(product types) X 3(product information types) experimental setting and measured dependent variables such as information usefulness, attitude toward the shopping mall, overall product quality, purchase intention and the revisiting intention. In the case of information usefulness and attitude toward the shopping mall were measured by multi-item scale. As a result of reliability test, Cronbach's Alpha value of each variable shows more than 0.6. Thus, we ensured that the internal consistency of items. 3.2. Manipulation check The main concern of this study is to verify the moderate effect by the product type of usage situation. indicates that our experimental manipulation of the moderate effect of the product type was successful. 3.3. Results As
    indicates, there was a significant main effect on the only one dependent variable(attitude toward the shopping mall) by the information types. As predicted, VR has highest mean value compared to other information types. Thus, H1 was partially supported. However, main effect by the product types was not found. To evaluate H2 and H3, a two-way ANOVA was conducted. As
    indicates, there exist the interaction effects on the three dependent variables(information usefulness, overall product quality and purchase intention) by the information types and the product types. As predicted, picture of the product with the real-person model has highest mean among the information types in the case of portable product. On the other hand, VR has highest mean among the information types in the case of installed product. Thus, H2 and H3 was supported. 4. Implications: The present study found the moderate effect by the product type of usage situation. Based on the findings the following managerial implications are asserted. First, it was found that information types are affect only the attitude toward the shopping mall. The meaning of this finding is that VR effects are not enough to understand the product itself. Therefore, we must consider when and how to use this VR tools. Second, it was found that there exist the interaction effects on the information usefulness, overall product quality and purchase intention. This finding suggests that consideration of usage situation helps consumer's understanding of product and promotes their purchase intention. In conclusion, not only product attributes but also product usage situations must be fully considered by the online retailers when they want to meet the needs of consumers.

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  • An Analysis of the Moderating Effects of User Ability on the Acceptance of an Internet Shopping Mall (인터넷 쇼핑몰 수용에 있어 사용자 능력의 조절효과 분석)

    • Suh, Kun-Soo
      • Asia pacific journal of information systems
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      • v.18 no.4
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      • pp.27-55
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      • 2008
    • Due to the increasing and intensifying competition in the Internet shopping market, it has been recognized as very important to develop an effective policy and strategy for acquiring loyal customers. For this reason, web site designers need to know if a new Internet shopping mall(ISM) will be accepted. Researchers have been working on identifying factors for explaining and predicting user acceptance of an ISM. Some studies, however, revealed inconsistent findings on the antecedents of user acceptance of a website. Lack of consideration for individual differences in user ability is believed to be one of the key reasons for the mixed findings. The elaboration likelihood model (ELM) and several studies have suggested that individual differences in ability plays an moderating role on the relationship between the antecedents and user acceptance. Despite the critical role of user ability, little research has examined the role of user ability in the Internet shopping mall context. The purpose of this study is to develop a user acceptance model that consider the moderating role of user ability in the context of Internet shopping. This study was initiated to see the ability of the technology acceptance model(TAM) to explain the acceptance of a specific ISM. According to TAM. which is one of the most influential models for explaining user acceptance of IT, an intention to use IT is determined by usefulness and ease of use. Given that interaction between user and website takes place through web interface, the decisions to accept and continue using an ISM depend on these beliefs. However, TAM neglects to consider the fact that many users would not stick to an ISM until they trust it although they may think it useful and easy to use. The importance of trust for user acceptance of ISM has been raised by the relational views. The relational view emphasizes the trust-building process between the user and ISM, and user's trust on the website is a major determinant of user acceptance. The proposed model extends and integrates the TAM and relational views on user acceptance of ISM by incorporating usefulness, ease of use, and trust. User acceptance is defined as a user's intention to reuse a specific ISM. And user ability is introduced into the model as moderating variable. Here, the user ability is defined as a degree of experiences, knowledge and skills regarding Internet shopping sites. The research model proposes that the ease of use, usefulness and trust of ISM are key determinants of user acceptance. In addition, this paper hypothesizes that the effects of the antecedents(i.e., ease of use, usefulness, and trust) on user acceptance may differ among users. In particular, this paper proposes a moderating effect of a user's ability on the relationship between antecedents with user's intention to reuse. The research model with eleven hypotheses was derived and tested through a survey that involved 470 university students. For each research variable, this paper used measurement items recognized for reliability and widely used in previous research. We slightly modified some items proper to the research context. The reliability and validity of the research variables were tested using the Crobnach's alpha and internal consistency reliability (ICR) values, standard factor loadings of the confirmative factor analysis, and average variance extracted (AVE) values. A LISREL method was used to test the suitability of the research model and its relating six hypotheses. Key findings of the results are summarized in the following. First, TAM's two constructs, ease of use and usefulness directly affect user acceptance. In addition, ease of use indirectly influences user acceptance by affecting trust. This implies that users tend to trust a shopping site and visit repeatedly when they perceive a specific ISM easy to use. Accordingly, designing a shopping site that allows users to navigate with heuristic and minimal clicks for finding information and products within the site is important for improving the site's trust and acceptance. Usefulness, however, was not found to influence trust. Second, among the three belief constructs(ease of use, usefulness, and trust), trust was empirically supported as the most important determinants of user acceptance. This implies that users require trustworthiness from an Internet shopping site to be repeat visitors of an ISM. Providing a sense of safety and eliminating the anxiety of online shoppers in relation to privacy, security, delivery, and product returns are critically important conditions for acquiring repeat visitors. Hence, in addition to usefulness and ease of use as in TAM, trust should be a fundamental determinants of user acceptance in the context of internet shopping. Third, the user's ability on using an Internet shopping site played a moderating role. For users with low ability, ease of use was found to be a more important factors in deciding to reuse the shopping mall, whereas usefulness and trust had more effects on users with high ability. Applying the EML theory to these findings, we can suggest that experienced and knowledgeable ISM users tend to elaborate on such usefulness aspects as efficient and effective shopping performance and trust factors as ability, benevolence, integrity, and predictability of a shopping site before they become repeat visitors of the site. In contrast, novice users tend to rely on the low elaborating features, such as the perceived ease of use. The existence of moderating effects suggests the fact that different individuals evaluate an ISM from different perspectives. The expert users are more interested in the outcome of the visit(usefulness) and trustworthiness(trust) than those novice visitors. The latter evaluate the ISM in a more superficial manner focusing on the novelty of the site and on other instrumental beliefs(ease of use). This is consistent with the insights proposed by the Heuristic-Systematic model. According to the Heuristic-Systematic model. a users act on the principle of minimum effort. Thus, the user considers an ISM heuristically, focusing on those aspects that are easy to process and evaluate(ease of use). When the user has sufficient experience and skills, the user will change to systematic processing, where they will evaluate more complex aspects of the site(its usefulness and trustworthiness). This implies that an ISM has to provide a minimum level of ease of use to make it possible for a user to evaluate its usefulness and trustworthiness. Ease of use is a necessary but not sufficient condition for the acceptance and use of an ISM. Overall, the empirical results generally support the proposed model and identify the moderating effect of the effects of user ability. More detailed interpretations and implications of the findings are discussed. The limitations of this study are also discussed to provide directions for future research.

    Studies on the Mechanical Properties of Weathered Granitic Soil -On the Elements of Shear Strength and Hardness- (화강암질풍화토(花崗岩質風化土)의 역학적(力學的) 성질(性質)에 관(關)한 연구(硏究) -전단강도(剪斷强度)의 영향요소(影響要素)와 견밀도(堅密度)에 대(對)하여-)

    • Cho, Hi Doo
      • Journal of Korean Society of Forest Science
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      • v.66 no.1
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      • pp.16-36
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      • 1984
    • It is very important in forestry to study the shear strength of weathered granitic soil, because the soil covers 66% of our country, and because the majority of land slides have been occured in the soil. In general, the causes of land slide can be classified both the external and internal factors. The external factors are known as vegetations, geography and climate, but internal factors are known as engineering properties originated from parent rocks and weathering. Soil engineering properties are controlled by the skeleton structure, texture, consistency, cohesion, permeability, water content, mineral components, porosity and density etc. of soils. And the effects of these internal factors on sliding down summarize as resistance, shear strength, against silding of soil mass. Shear strength basically depends upon effective stress, kinds of soils, density (void ratio), water content, the structure and arrangement of soil particles, among the properties. But these elements of shear strength work not all alone, but together. The purpose of this thesis is to clarify the characteristics of shear strength and the related elements, such as water content ($w_o$), void ratio($e_o$), dry density (${\gamma}_d$) and specific gravity ($G_s$), and the interrelationship among related elements in order to decide the dominant element chiefly influencing on shear strength in natural/undisturbed state of weathered granitic soil, in addition to the characteristics of soil hardness of weathered granitic soil and root distribution of Pinus rigida Mill and Pinus rigida ${\times}$ taeda planted in erosion-controlled lands. For the characteristics of shear strength of weathered granitic soil and the related elements of shear strength, three sites were selected from Kwangju district. The outlines of sampling sites in the district were: average specific gravity, 2.63 ~ 2.79; average natural water content, 24.3 ~ 28.3%; average dry density, $1.31{\sim}1.43g/cm^3$, average void ratio, 0.93 ~ 1.001 ; cohesion, $ 0.2{\sim}0.75kg/cm^2$ ; angle of internal friction, $29^{\circ}{\sim}45^{\circ}$ ; soil texture, SL. The shear strength of the soil in different sites was measured by a direct shear apparatus (type B; shear box size, $62.5{\times}20mm$; ${\sigma}$, $1.434kg/cm^2$; speed, 1/100mm/min.). For the related element analyses, water content was moderated through a series of drainage experiments with 4 levels of drainage period, specific gravity was measured by KS F 308, analysis of particle size distribution, by KS F 2302 and soil samples were dried at $110{\pm}5^{\circ}C$ for more than 12 hours in dry oven. Soil hardness represents physical properties, such as particle size distribution, porosity, bulk density and water content of soil, and test of the hardness by soil hardness tester is the simplest approach and totally indicative method to grasp the mechanical properties of soil. It is important to understand the mechanical properties of soil as well as the chemical in order to realize the fundamental phenomena in the growth and the distribution of tree roots. The writer intended to study the correlation between the soil hardness and the distribution of tree roots of Pinus rigida Mill. planted in 1966 and Pinus rigida ${\times}$ taeda in 199 to 1960 in the denuded forest lands with and after several erosion control works. The soil texture of the sites investigated was SL originated from weathered granitic soil. The former is situated at Py$\ddot{o}$ngchangri, Ky$\ddot{o}$m-my$\ddot{o}$n, Kogs$\ddot{o}$ng-gun, Ch$\ddot{o}$llanam-do (3.63 ha; slope, $17^{\circ}{\sim}41^{\circ}$ soil depth, thin or medium; humidity, dry or optimum; height, 5.66/3.73 ~ 7.63 m; D.B.H., 9.7/8.00 ~ 12.00 cm) and the Latter at changun-long Kwangju-shi (3.50 ha; slope, $12^{\circ}{\sim}23^{\circ}$; soil depth, thin; humidity, dry; height, 10.47/7.3 ~ 12.79 m; D.B.H., 16.94/14.3 ~ 19.4 cm).The sampling areas were 24quadrats ($10m{\times}10m$) in the former area and 12 in the latter expanding from summit to foot. Each sampling trees for hardness test and investigation of root distribution were selected by purposive selection and soil profiles of these trees were made at the downward distance of 50 cm from the trees, at each quadrat. Soil layers of the profile were separated by the distance of 10 cm from the surface (layer I, II, ... ...). Soil hardness was measured with Yamanaka soil hardness tester and indicated as indicated soil hardness at the different soil layers. The distribution of tree root number per unit area in different soil depth was investigated, and the relationship between the soil hardness and the number of tree roots was discussed. The results obtained from the experiments are summarized as follows. 1. Analyses of simple relationship between shear strength and elements of shear strength, water content ($w_o$), void ratio ($e_o$), dry density (${\gamma}_d$) and specific gravity ($G_s$). 1) Negative correlation coefficients were recognized between shear strength and water content. and shear strength and void ratio. 2) Positive correlation coefficients were recognized between shear strength and dry density. 3) The correlation coefficients between shear strength and specific gravity were not significant. 2. Analyses of partial and multiple correlation coefficients between shear strength and the related elements: 1) From the analyses of the partial correlation coefficients among water content ($x_1$), void ratio ($x_2$), and dry density ($x_3$), the direct effect of the water content on shear strength was the highest, and effect on shear strength was in order of void ratio and dry density. Similar trend was recognized from the results of multiple correlation coefficient analyses. 2) Multiple linear regression equations derived from two independent variables, water content ($x_1$ and dry density ($x_2$) were found to be ineffective in estimating shear strength ($\hat{Y}$). However, the simple linear regression equations with an independent variable, water content (x) were highly efficient to estimate shear strength ($\hat{Y}$) with relatively high fitness. 3. A relationship between soil hardness and the distribution of root number: 1) The soil hardness increased proportionally to the soil depth. Negative correlation coefficients were recognized between indicated soil hardness and the number of tree roots in both plantations. 2) The majority of tree roots of Pinus rigida Mill and Pinus rigida ${\times}$ taeda planted in erosion-controlled lands distributed at 20 cm deep from the surface. 3) Simple linear regression equations were derived from indicated hardness (x) and the number of tree roots (Y) to estimate root numbers in both plantations.

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