• Title/Summary/Keyword: reliability design and test

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Comparison of Measured Natural Frequencies of a Railway Bridge Specimen Between Different Excitation Methods (철도교량 시험체의 가진방법에 따른 고유진동수 측정치 변동에 대한 비교 분석)

  • Kim, Sung-Il;Lee, Jungwhee;Lee, Pil-Goo;Kim, Choong-Eon
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.30 no.6A
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    • pp.535-542
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    • 2010
  • Precise estimation of a structure's dynamic characteristics is indispensable for ensuring stable dynamic responses during lifetime especially for the structures which can experience resonance such as railway bridges. In this paper, the results of forced vibration tests of different excitation methods (vibration exciter and impact hammer) are compared to examine the differences and the cause of differences of extracted natural frequencies. Consequently a natural frequency modification method is suggested to eliminate effects of non-structural disturbance factors. Also, sequential forced vibration tests are performed before and after track construction according to the construction stage of a railway bridge, and the variation of natural frequencies are examined. Effect of added mass of vibration exciter and variation of support condition due to the level of excitation force are concluded as the major cause of natural frequency differences. Thus eliminating these effects can enhance the reliability of the extracted natural frequencies. Construction of track affects not only the mass of structure but also the stiffness of the structure. Also, the amount of increase in stiffness varies according to the level of structural deflection. Therefore, reasonable estimation of the level of structural response during operation is important for precise natural frequency calculation at design phase.

Estimation of Fatigue Crack Initiation Life Distribution by Multi-notched Specimen (다응력집중부(多應力集中部)를 가진 판(判)에 의(依)한 피로균열(疲勞龜裂) 발생수명(發生壽命) 분포(分布) 추정(推定))

  • S.W. Kang;D.S. Uom;J.H. Lee
    • Journal of the Society of Naval Architects of Korea
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    • v.29 no.4
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    • pp.234-243
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    • 1992
  • Fatigue crack initiation life has a wide scatter and this makes the fatigue design of structural members difficult. In order to make the fatigue life distribution clear, it is required to prepare a large number of specimens and repeat the fatigue tests under the same loading condition. Such fatigue tests usually take much time and cost. In this study, a fatigue testing method using a multi-notched test specimen for the purpose of estimating the distribution function of fatigue crack initiation life by small number of fatigue tests is used. The purpose of this study is to verify the above fatigue testing method of a multi-notched specimen by using Bayesian reliability analysis, Least square method and Skewness method for the determination of unknown Weibull parameters. The multi-notched specimen is a specimen in which several tens of statistically identical notches are prepared.

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Numerical Study on the Cooling Characteristics of a Passive-Type PEMFC Stack (수동공기공급형 고분자 전해질 연료전지 스택에서의 냉각특성에 대한 전산해석 연구)

  • Lee, Jae-Hyuk;Kim, Bo-Sung;Lee, Yong-Taek;Kim, Yong-Chan
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.34 no.8
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    • pp.767-774
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    • 2010
  • In a passive-type PEMFC stack, axial fans operate to supply both oxidant and coolant to cathode side of the stack. It is possible to make a simple system because the passive-type PEMFC stack does not require additional cooling equipment. However, the performance of a cooling system in which water is used as a coolant is better than that of the air-cooling system. To ensure system reliability, it is essential to make cooling system effective by adopting an optimal stack design. In this study, a numerical investigation has been carried out to identify an optimum cooling strategy. Various channel configurations were applied to the test section. The passive-type PEMFC was tested by varying airflow rate distribution at the cathode side and external heat transfer coefficient of the stack. The best cooling performance was achieved when a channel with thick ribs was used, and the overheating at the center of the stack was reduced when a case in which airflow was concentrated at the middle of the stack was used.

A Study Related to Adolescent Students' School Uniform Behavior and Attitude toward Appearance (청소년의 교복행동과 외모에 대한 태도와의 관련 연구)

  • Han, Mi-Hwa;Lee, Eun-Hee
    • Journal of Korean Home Economics Education Association
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    • v.21 no.2
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    • pp.23-43
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    • 2009
  • This study examined the relativity between school uniform behavior(especially attitude toward school uniform, school uniform satisfaction, school uniform alteration) and attitude toward appearance in the adolescence. From November to December in 2007, 898 middle school and high school students from four schools in Jeollabuk-do Province were analyzed and the influence of relevant variables was understood to gather basic information about the fashion life in the adolescence. This study used SPSS 11.5 for Windows Program to conduct frequency analysis, factor analysis, reliability analysis, ${\chi}^2$-test, t-test, One-way ANOVA, Duncan's multiple comparison test, and Pearson's correlation. The following summarizes the findings of this study: The results of analysing the factors to the response attitude toward uniforms and attitude toward appearance and clothing attitude emerged four dimensions(fashion, symbolism, cleanliness, alternation), three dimensions(needs value conformity toward appearance). In attitude toward uniform, female students were more actively altering their uniforms than male students and middle school students were more sensitive to trends than high school students. However, high school students were more aware of the cleanliness and alteration of uniforms. Overall, most students were not very satisfied with their uniforms (design, color, texture). When students' attitude toward appearance and demographical characteristics were examined, it was found that female students were more aware of desire, value, and conformity in appearances than male students. By age, it was found that high school students were more aware than middle school students. Also, students receiving KRW 30,000 or more for monthly allowance were more aware than others who receive a lower amount between KRW 10,000 and KRW 20,000. Therefore, most students(62.1%) have experiences in altering uniforms. Especially, more female students and more high school students had such experiences. Uniform alteration is more related to attitude to appearance. In other words, students who choose to alter their uniforms are highly aware of desire, value, and conformity toward appearance. Students who are satisfied with all factors regarding attitude toward uniform, except for alteration, did not alter their uniforms that much. In addition, when the relativity between students' attitude toward appearance with uniform was considered, students that are not very satisfied with their uniforms were more aware of desire, value, and conformity toward appearance. In conclusion, it was found that students' attitude toward appearance and school uniform behavior are closely related and their interests in appearance lead to alteration of uniforms, the clothing in which they spend most time of the day. From now on, students' opinions shall be considered when selecting or designing school uniforms.

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The Effects of Self-Congruity and Functional Congruity on e-WOM: The Moderating Role of Self-Construal in Tourism (중국 관광객의 온라인 구전에 대한 자아일치성과 기능일치성의 효과: 자기해석의 조절효과를 중심으로)

  • Yang, Qin;Lee, Young-Chan
    • The Journal of Information Systems
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    • v.25 no.1
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    • pp.1-23
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    • 2016
  • Purpose Self-congruity deals with the effect of symbolic value-expressive attributes on consumer decision and behavior, which is the theoretical foundation of the "non-utilitarian destination positioning". Functional congruity refers to utilitarian evaluation of a product or service by consumers. In addition, recent years, social network services, especially mobile social network services have created many opportunities for e-WOM communication that enables consumers to share personal consumption related information anywhere at any time. Moreover, self-construal is a hot and popular topic that has been discussed in the field of modem psychology as well as in marketing area. This study aims to examine the moderating effect of self-construal on the relationship between self-congruity, functional congruity and tourists' positive electronic word of mouth (e-WOM). Design/methodology/approach In order to verify the hypotheses, we developed a questionnaire with 32 survey items. We measured all the items on a five-point Likert-type scale. We used Sojump.com to collect questionnaire and gathered 218 responses from whom have visited Korea before. After a pilot test, we analyzed the main survey data by using SPSS 20.0 and AMOS 18.0, and employed structural equation modeling to test the hypotheses. We first estimated the measurement model for its overall fit, reliability and validity through a confirmatory factor analysis and used common method bias test to make sure that whether measures are affected by common-method variance. Then we tested the hypotheses through the structural model and used regression analysis to measure moderating effect of self-construal. Findings The results reveal that the effect of self-congruity on tourists' positive e-WOM is stronger for tourists with an independent self-construal compared with those with interdependent self-construal. Moreover, it shows that the effect of functional congruity on tourists' positive e-WOM becomes salient when tourists' self-construal is primed to be interdependent rather than independent. We expect that the results of this study can provide important implications for academic and practical perspective.

Relation of Social Security Network Building, Civil Culture and Community Unity (사회안전망구축과 시민문화 및 지역사회결속의 관계)

  • shin, Sang-Tae;Kim, Chan-Sun
    • Convergence Security Journal
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    • v.15 no.3_2
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    • pp.59-70
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    • 2015
  • This study aims at exploring relation of social security network building, civil culture and community unity. To achieve the purpose, this study selected the general citizens in Seoul Region (Gangdong, Gangseo, Gangnam and Gangbuk) from Jul. 15 to Sept. 15, 2014 as population and sampled 400 people using cluster random sampling. Excluding unhonest data, the number of cases used for the final analysis is 337 people. The collected data were analyzed for the study purpose using SPSSWIN 18.0, as statistical techniques, factor analysis, reliability analysis, correlation analysis, t-test, one-way ANOVA, multiple regression analysis, path analysis etc. were used. First, social security network building has an effect on civil culture. That is, the more activated voluntary crime prevention activity, the higher order law-abiding spirit. The more activated local government security education, police public order service, the higher awareness of participation becomes. First, social security network building has an effect on civil culture. That is, the more activated voluntary crime prevention activity, the higher order law-abiding spirit. The more activated local government security education, police public order service, the higher awareness of participation becomes. The more activated voluntary crime prevention activity, street CCTV facilities, police public order service, the higher tolerance spirit becomes. On the contrary, street CCTV facilities reduce citizens' autonomy. Second, social security network building has an effect on community unity. The more activated street CCTV facilities, police public order service, crime prevention design, the higher a sense of stability becomes. The more activated local government security education, police public order service, crime prevention design, the higher awareness of community becomes. The more activated voluntary crime prevention activity, government security education, police public order service, crime prevention design, the higher community institution becomes. Third, civil culture has an effect on community unity. That is, the more activated awareness of community, tolerance spirit, the higher a sense of stability, awareness of community and community system become. Fourth, social security network building has an effect on civil culture and community unity. That is, social security network building has a low effect community institution directly, but if civil culture is enhanced through social security network building, then it has a high effect on community unity.

A Study on the Various Attributes of E-Sport Influencing Flow and Identification (e-스포츠의 다양한 속성이 유동(flow)과 동일시에 미치는 영향에 관한 연구)

  • Suh, Mun-Shik;Ahn, Jin-Woo;Kim, Eun-Young;Um, Seong-Won
    • Journal of Global Scholars of Marketing Science
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    • v.18 no.1
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    • pp.59-80
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    • 2008
  • Recently, e-sports are growing with potentiality as a new industry with conspicuous profit model. But studies that dealing with e-sports are not enough. Hence, proposes of this paper are both to establish basic model that is for the design of e-sport marketing strategy and to contribute toward future studies which are related to e-sports. Recently, the researches to explain sports-sponsorship through the identification theory have been discovered. Many researches say that somewhat proper identification is a requirement for most sponsors to improve the their images which is essential to sponsorship activity. Consequently, the research for sponsorship associated with identification in the e-sports, not in the physical sports is the core sector of this study. We extracted the variables from online's major characteristics and existing sport sponsorship researches. First, because e-sports mean the tournaments or leagues in the use of online game, the main event of the game is likely to call it online game. Online media's attributes are distinguished from those of offline. Especially, interactivity, anonymity, and expandibility as a e-sport game attributes are able to be mentioned. So, these inherent online attributes are examined on the relationship with flow. Second, in physical sports games, Fisher(1998) revealed that team similarity and team attractivity were positively related to team identification. Wann(1996) said that the result of former game influenced the evaluation of the next game, then in turn has an effect on the identification of team supporters. Considering these results in the e-sports side, e-sports gamer' attractivity, similarity, and match result seem to be important precedent variables of the identification with a gamer. So, these e-sport gamer attributes are examined on the relationship with both flow and identification with a gamer. Csikszentmihalyi(1988) defined the term flow as feeling status for him to be making current positive experience optimally. Hoffman and Novak(1996) also said that if a user experienced the flow he would visit a website without any reward. Therefore flow might be positively associated with user's identification with a gamer. And, Swanson(2003) disclosed that team identification influenced the positive results of sponsorship, which included attitude toward sponsors, sponsor patronage, and satisfaction with sponsors. That is, identification with a gamer expect to be connected with corporation identification significantly. According to the above, we can design the following research model. All variables used in this study(interactivity, anonymity, expandibility, attractivity, similarity, match result, flow, identification with a gamer, and identification with a sponsor) definitely were defined operationally underlying precedent researches. Sample collection was carried out to the person who has an experience to have enjoyed e-sports during June 2006. Much portion of samples is men because much more men than women enjoy e-sports in general. Two-step approach was used to test the hypotheses. First, confirmatory factor analysis was committed to guarantee the validity and reliability of variables. The results showed that all variables had not only intensive and discriminant validity, but also reliability. Then, research model was examined with fully structural equation using LISREL 8.3 version. The fitness of the suggested model mostly was at the acceptable level. Shortly speaking about the results, first of all, in e-sports game attributes, only interactivity which is called a basic feature in online situation affected flow positively. Secondly, in e-sports gamer's attributes, similarity with a gamer and match result influenced flow positively, but there was no significant effect in the relationship between the attractivity of a gamer and flow. And as expected, similarity had an effect on identification with a gamer significantly. But unexpectedly attractivity and match result did not influence identification with a gamer significantly. Just the same as the fact verified in the many precedent researches, flow greatly influenced identification with a gamer, and identification with a gamer continually had an influence on the identification with a sponsor significantly. There are some implications in these results. If the sponsor of e-sports supports the pro-game player who absolutely should have the superior ability to others and is similar to the user enjoying e-sports, many amateur gamers will feel much of the flow and identification with a pro-gamer, and then after all, feel the identification with a sponsor. Such identification with a sponsor leads people enjoying e-sports to have purchasing intention for products produced by the sponsor and to make a positive word-of-mouth for those products or the sponsor. For the future studies, we recommend a few ideas. Based on the results of this study, it is necessary to find new variables relating to the e-sports, which is not mentioned in this study. For this work to be possible, qualitative research seems to be needed to consider the inherent e-sport attributes. Finally, to generalize the results related to e-sports, a wide range of generations not a specific generation should be researched.

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A study on the employment preparation cost and attitude of college student for Job-seeking (국내 대학생의 취업태도 및 취업준비 비용에 관한 연구)

  • Chung, Bhum-Suk;Jeong, Hwa-Min
    • Management & Information Systems Review
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    • v.33 no.4
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    • pp.1-19
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    • 2014
  • This Study focuses on the university students' job attitude and cost of employment preparation. Nowadays, many university and college students spend a big money improving their employment preparation such as studying on foreign language, getting various kinds of certificates and tooth correction, clothing etc. for employment interview. This study investigated the cost of employment preparation and Job attitude of the 484 students of universities and colleges, the analysis of the collected data was conducted with SPSS 12.0 program by using frequency analysis, factor analysis, reliability assessment, correlation test, t-test, one way ANOVA. The university students paid more costs of employment preparation such as a language training abroad, a private training, and clothing than the college students. Also, Allied social science students paid more costs of the language training abroad, and clothing than allied computer science and allied design students. The female students paid more money than male students for tooth correction. The costs of language training abroad, private training and clothing are affected the students' socioeconomic background of a home. Regarding the job attitude of students, the university students are feeling more positive than the college students of the employment efficacy and cognition of the education environment. As result, the differences in the cost of employment preparation by the university type, faculty major course, their sex, and socioeconomic background of a home. The student's employment-efficacy and cognition of the education environment are also differences between the university and the college students. So, to improve the job attitude, developing their ability for employment preparation, educational programs should be arranged in school and continuous researches are needed.

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An Exploratory Study on the Effects of Relational Benefits and Brand Identity : mediating effect of brand identity (관계혜택과 브랜드 동일시의 역할에 관한 탐색적 연구: 브랜드 동일시의 매개역할을 중심으로)

  • Bang, Jounghae;Jung, Jiyeon;Lee, Eunhyung;Kang, Hyunmo
    • Asia Marketing Journal
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    • v.12 no.2
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    • pp.155-175
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    • 2010
  • Most of the service industries including finance and telecommunications have become matured and saturated. The competitions have become severe while the differences among brands become smaller. Therefore maintaining good relationships with customers has been critical for the service providers. In case of credit card and debit card, the similar patterns are shown. It is important for them to maintain good relationships with customers, and therefore, they have used marketing program which provides customized services to customers and utilizes the membership programs. Not only do they build and maintain good relationships, but also highlight their brands from the emotional aspects. For example, KB Card or Hyundai Card uses well-known designers' works for their credit card design. As well, they differentiate the designs of credit cards to stress on their brand personalities. BC Card introduced the credit card with perfume that a customer would like. Even though the credit card is small and not shown to public easily, it becomes more important for those companies to touch the customers' feelings with the brand personalities and their images. This is partly because of changes in consumers' lifestyles. Y-generations becomes highly likely to express themselves in many different ways and more emotional than X-generations. For the Y-generations, therefore, even credit cards in the wallet should be personalized and well-designed. In line with it, credit cards with good design can be seen as an example of brand identity, where different design for each customer can be used to recognize the membership groups that customers want to belong. On the other hand, these credit card companies offer the special treatment benefits for those customers who are heavy users for the cards. For example, those customers who love sports will receive some special discounts when they use their credit cards for sports related products. Therefore this study attempted to explore the relationships between relational benefits, brand identification and loyalty. It has been well known that relational benefits and brand identification lead to loyalty independently from many other studies, but there has been few study to review all the three variables all together in a research model. Furthermore, as reviewed above, in the card industry, many companies attempt to associate the brand image with their products to fit their customers' lifestyles while relational benefits are still playing an important role for their business. Therefore in our research model, relational benefits, brand identification, and loyalty are all included. We focus on the mediating effect of brand identification. From the relational benefits perspective, only special treatment benefit and confidence benefit are included. Social benefit is not applicable for this credit card industry because not many cases of face-to-face interaction can be found. From the brand identification perspective, personal brand identity and social brand identity are reviewed and included in the model. Overall, the research model emphasizes that the relationships between relational benefits and loyalty will be mediated by the effect of brand identification. The effects of relational benefits which are confidence benefit and special treatment benefits on loyalty will be realized when they fit to the personal brand identity and social brand identity. In the research model, therefore, the relationships between confidence benefit and social brand identity, and between confidence benefit and personal identity are hypothesized while the effects of special treatment benefit on social brand identity and personal brand identity are hypothesized. Loyalty, then, is hypothesized to have positive relationships with personal brand identity and social brand identity. In addition, confidence benefit among the relational benefits is expected to have a direct, positive relationship with loyalty because confidence benefit has been recognized as a critical factor for good relationships and satisfaction. Data were collected from college students who have been using either credit cards or debit cards. College students were regarded good subjects because they are in Y-generation cohorts and have tendency to express themselves more. Total sample size was two hundred three at the beginning, but after deleting those data with many missing values, one hundred ninety-seven data points were remained and used for the model testing. Measurement items were brought from the previous literatures and modified for this research. To test the reliability, using SPSS 14, chronbach's α was examined and all the values were from .874 to .928 exceeding over .7. Using AMOS 7.0, confirmatory factor analysis was conducted to investigate the measurement model. The measurement model was found good fit with χ2(67)=188.388 (p= .000), GFI=.886, AGFI=.821, CFI=.941, RMSEA=.096. Using AMOS 7.0, structural equation modeling has been used to analyze the research model. Overall, the research model fit were χ2(68)=188.670 (p= .000), GFI=.886, AGFI=,824 CFI=.942, RMSEA=.095 indicating good fit. In details, all the paths hypothesized in the research model were found significant except for the path from social brand identity to loyalty. Personal brand identity leads to loyalty while both confidence benefit and special treatment benefit have a positive relationships with personal and social identities. As well, confidence benefit has a direct positive effect on loyalty. The results indicates the followings. First, personal brand identity plays an important role for credit/debit card usage. Therefore even for the products which are not shown to public easy, design and emotional aspect can be important to fit the customers' lifestyles. Second, confidence benefit and special treatment benefit have a positive effects on personal brand identity. Therefore it will be needed for marketers to associate the special treatment and trust and confidence benefits with personal image, personality and personal identity. Third, this study found again the importance of confidence and trust. However interestingly enough, social brand identity was not found to be significantly related to loyalty. It can be explained that the main sample of this study consists of college students. Those strategies to facilitate social brand identity are focused on high social status groups while college students have not been established their status yet.

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A Review on Ultimate Lateral Capacity Prediction of Rigid Drilled Shafts Installed in Sand (사질토에 설치된 강성현장타설말뚝의 극한수평지지력 예측에 관한 재고)

  • Cho Nam Jun;Kulhawy F.H
    • Journal of the Korean Geotechnical Society
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    • v.21 no.2
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    • pp.113-120
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    • 2005
  • An understanding of soil-structure interaction is the key to rational and economical design for laterally loaded drilled shafts. It is very difficult to formulate the ultimate lateral capacity into a general equation because of the inherent soil nonlincarity, nonhomogeneity, and complexity enhanced by the three dimensional and asymmetric nature of the problem though extensive research works on the behavior of deep foundations subjected to lateral loads have been conducted for several decades. This study reviews the four most well known methods (i.e., Reese, Broms, Hansen, and Davidson) among many design methods according to the specific site conditions, the drilled shaft geometric characteristics (D/B ratios), and the loading conditions. And the hyperbolic lateral capacities (H$_h$) interpreted by the hyperbolic transformation of the load-displacement curves obtained from model tests carried out as a part of this research have been compared with the ultimate lateral capacities (Hu) predicted by the four methods. The H$_u$ / H$_h$ ratios from Reese's and Hansen's methods are 0.966 and 1.015, respectively, which shows both the two methods yield results very close to the test results. Whereas the H$_u$ predicted by Davidson's method is larger than H$_h$ by about $30\%$, the C.0.V. of the predicted lateral capacities by Davidson is the smallest among the four. Broms' method, the simplest among the few methods, gives H$_u$ / H$_h$ : 0.896, which estimates the ultimate lateral capacity smaller than the others because some other resisting sources against lateral loading are neglected in this method. But it results in one of the most reliable methods with the smallest S.D. in predicting the ultimate lateral capacity. Conclusively, none of the four can be superior to the others in a sense of the accuracy of predicting the ultimate lateral capacity. Also, regardless of how sophisticated or complicated the calculating procedures are, the reliability in the lateral capacity predictions seems to be a different issue.