• Title/Summary/Keyword: Program design and evaluation

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Stability Analysis and Reliability Evaluation of the Pretensioned Soil Nailing System (프리텐션 쏘일네일링 시스템의 안정해석 및 신뢰도 분석)

  • 김홍택;강인규;박사원;고용일;권영호
    • Journal of the Korean Geotechnical Society
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    • v.15 no.2
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    • pp.105-127
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    • 1999
  • Application of the soil nailing method is continuously extended in maintaining stable excavations and slopes. Occasionally, however, ground anchor support system may not be used because of space limitations in urban excavation sites nearby the existing structures. In this case, soil nailing system with relatively short length of nails could be efficiently adopted as an alternative method. The general soil nailing support system, however, may result in excessive deformations particularly in an excavation zone of the existing weak subsoils. Pretensioning the soil nails then, could play important roles in reducing deformations mainly in an upper part of the nailed-soil excavation system as well as improving local stability. In the present study, the analytical procedure and design technique are proposed to evaluate maximum pretension force and stability of the pretensioned soil nailing system. Also proposed are techniques to determine the required thickness of a shotcrete facing and to estimate probability of a failure against the punching shear. The predicted results are compared with the limited measurements obtained from the excavation site constructed by using the pretensioned soil nails. Based on the proposed procedure and technique, effects of the radius of a influence circle and dilatancy angle on the thickness of a shotcrete facing, bonded length and safety factors are analyzed. In addition, effects of the reduction of deformations expected by pretensioning of the soil nails are examined in detail throughout an illustrative example and FLAC$^{2D}$ program analysis.s.

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Evaluation of Fire Resistance of Unprotected Concrete-filled Rectangular Steel Tubular Columns under Axial Loading (재하가열시험에 의한 무내화피복 콘크리트충전 각형강관기둥의 내화성능평가)

  • Ahn, Jae Kwon;Lee, Cheol Ho
    • Journal of Korean Society of Steel Construction
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    • v.26 no.4
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    • pp.323-334
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    • 2014
  • In this paper, experimental program and associated numerical study were carried out to evaluate the fire resistance of unprotected concrete-filled rectangular steel tubular (CFT) columns subjected to the standard fire. The key testing parameters included the length effect, the load ratio, and the sectional dimensions of the CFT columns. Temperature distribution and axial deformation of the CFT column specimens were measured and analyzed. Rather early local buckling of steel tubes was observed in all the specimens. This caused subsequent load transfer from steel tube to concrete, and eventually triggered concrete crushing, or complete loss of the load bearing capacity of the column. This implies that the limit state of local buckling as well as overall flexural buckling should be incorporated in fire design procedure. As expected, the fire resistance time of specimen with higher load ratio consistently lessened. The prediction of fire resistance time of unprotected CFT columns based on the limiting steel temperature in current design codes or the formula proposed by previous studies is slightly conservative compared to the fire test results available. To establish the finite element analysis model that can be used to predict the thermal and structural behaviour of unprotected CFT columns in fire, the fully coupled thermal-stress analysis was also tried by using the commercial code ABAQUS. The numerical results showed a reasonable global correlation with the experimental results.

Effect of Horticultural Therapy on the Stress and Serum Cortisol of Demented Elders (원예치료가 치매노인의 스트레스 및 혈중 코티졸 호르몬에 미치는 영향)

  • Yun, Suk-Young;Choi, Byung-Jin
    • Horticultural Science & Technology
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    • v.28 no.5
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    • pp.891-894
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    • 2010
  • This study was conducted in order to examine the effects of horticultural therapy on stress in demented elders, and for this purpose, we analyzed stress-related physiological changes in demented elders under the care of an elderly facility who had not taken medication and consented to blood tests. The horticultural therapy program included only flower decoration, which was preferred by the participants, aiming ultimately to reduce stress. First, a one-to-one session was given for forming rapport and the horticultural therapist had many conversations about plants with the elders. Furthermore, the participants were induced to be absorbed into the horticultural activities, though a short while, so that they might forget troubles. Evaluation was made by measuring subjective stress and the blood cortisol hormone concentration before and after the horticultural therapy and examining differences between them. Subjective stress increased from 12.88 to 17.88 in the control group, but decreased significantly from 13.88 before the therapy to 6.38 after in the experimental group (p = 0.007). When the blood cortisol hormone level was measured as a physiological indicator of stress, it decreased significantly from $11.33{\mu}g{\cdot}L^{-1}$ before the horticultural therapy to $9.85{\mu}g{\cdot}L^{-1}$ after (p = 0.037). These results suggest that horticultural therapy reduces the blood cortisol hormone level and is effective in easing stress.

Evaluation on Fire Available Safe Egress Time of Commercial Buildings based on Artificial Neural Network (인공신경망 기반 상업용 건축물의 화재 피난허용시간 평가)

  • Darkhanbat, Khaliunaa;Heo, Inwook;Choi, Seung-Ho;Kim, Jae-Hyun;Kim, Kang Su
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.25 no.6
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    • pp.111-120
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    • 2021
  • When a fire occurs in a commercial building, the evacuation route is complicated and the direction of smoke and flame is similar to that of the egress route of occupants, resulting in many casualties. Performance-based evacuation design for buildings is essential to minimize human casualties. In order to apply the performance-based evacuation design to buildings, it requires a complex fire simulation for each building, demanding a large amount of time and manpower. In order to supplement this, it would be very useful to develop an Available Safe Egress Time (ASET) prediction model that can rationally derive the ASET without performing a fire simulation. In this study, the correlations between fire temperature with visibility and toxic gas concentration were investigated through a fire simulation on a commercial building, from which databases for the training of artificial neural networks (ANN) were created. Based on this, an ANN model that can predict the available safe egress time was developed. In order to examine whether the proposed ANN model can be applied to other commercial buildings, it was applied to another commercial building, and the proposed model was found to estimate the available safe egress time of the commercial building very accurately.

A Study on Image Preferences of Fashion Product According to Life-Style Groups -Focused on Middle-Aged Women between 35 and 59 Years Old- (라이프스타일 유형에 따른 패션 제품의 이미지 선호도(제 1보) -35$\sim$59세 중년 여성을 중심으로-)

  • Shim, Jung-Hee;Ywoun, Myeong-Heum
    • Archives of design research
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    • v.20 no.1 s.69
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    • pp.143-154
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    • 2007
  • The purpose of this study is to investigate fashion product image evaluation according to life-style groups of middle-aged women. The subject of investigation was 352 middle-aged women from 35 to 59 living in Daegu by random sampling method in April and May, 2005. The investigation was carried out by questionnaires which were composed of 3 sections: Fashion product image measure, Life style research and demographic variables(age, academic background, occupation, monthly clothing allowance, monthly income). The statistical methods to analyze the data were frequency, percentage, average, factor analysis, cluster analysis, ANOVA, Duncan's multiple range test. The results are summarized as follows: 1. As a result of factor analysis for fashion product image, the four factors including noble image, bold image, practical image, female image were extracted. 2. Middle-aged women were classified into four life-style groups including tradition oriented group, negative oriented group, activity oriented group and appearance oriented group. 3. Significant differences in fashion product image preferences according to life-style groups were found. Tradition oriented group preferred noble image and practical image. Negative oriented group tended to pursue practical image. Activity oriented group pursued a bold image. Appearance oriented group liked a noble image the best and then noble image, bold image in order.

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Evaluation on machining accuracy according to convergence angle and radius of curvature value used for fabricating custom abutments (맞춤형 지대주 제작에 사용되는 수렴 각과 곡률 반경의 값에 따른 가공 정확도 평가)

  • Hong, Min-Ho;Choi, Sung-Min;Kwon, Tae-Yub
    • Korean Journal of Dental Materials
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    • v.44 no.4
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    • pp.329-336
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    • 2017
  • This study evaluates the machining accuracy of the custom abutment design according to the selected convergence angle and radius of curvature value in the CAD program. Ten custom abutments were designed based on dental CAD. And then, the fabricated custom abutment was scanned ten times using a contact scanner. The data of the scanned custom abutment was saved as "Test STL" file. The Geomagic studio software was used to superposition each exported as an "Test STL" file with the CAD-reference-model STL file (CRM) specified by the same name. In the experimental results, the A8 group (convergence angle $8^{\circ}$) showed lower error than the A4 group (convergence angle $4^{\circ}$) . In addition, the higher the radius of curvature, the less error in the top and chamfer regions of the custom abutment (p< 0.05). Overall, the convergence angle and radius of curvature value in the custom abutment design were found to affect the machining accuracy.

Development of a Crash Cushion Using the Frictional and Inertial Energy by Computer Simulation (컴퓨터 시뮬레이션에 의한 관성과 마찰 에너지를 이용하는 충격흡수시설의 개발)

  • Kim, Dong-Seong;Kim, Kee-Dong;Ko, Man-Gi;Kim, Kwang-Ju
    • Journal of the Korean Society of Hazard Mitigation
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    • v.9 no.2
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    • pp.23-30
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    • 2009
  • Crash cushions are protective devices that prevent errant vehicles from impacting on fixed objects. This function is accomplished by gradually decelerating a vehicle to a safe stop in a relatively short distance. Commonly used crash cushions generally employ one of two concepts to accomplish this function. The first concept involves the absorption of the kinetic energy of a moving vehicle by crushable or plastically deformable materials and the other one involves the transfer of the momentum of a moving vehicle to an expendable mass of material located in the vehicle's path. Crash cushions using the first concept are generally referred to as compression crash cushions and crash cushions using the other concept are generally referred to as inertial crash cushion. The objective of this research is the development of a compression-type crash cushion by employing the two concepts simultaneously. To minimize the number of full-scale crash tests for the development of the crash cushion, preliminary design guide considering inertial and frictional energy absorption was constructed and computer simulation was performed. LS-DYNA program, which is most widely used to analyze roadside safety features, was used for the computer simulation. The developed crash cushion satisfied the safety evaluation criteria for various impact conditions of CC2 performance level in the Korean design guide.

The impacts of the experince of donation for education to improve the teaching efficacy of pre-technology teacher with Invent touring activity (발명체험 교육기부활동이 예비기술교사의 교수 효능감에 미치는 영향)

  • Choi, Yu-Hyun;Lim, Yun-Jin;Lee, Eun-Sang;Lee, Dong-Won
    • 대한공업교육학회지
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    • v.38 no.2
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    • pp.156-175
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    • 2013
  • The purpose of this study was to verify that the impacts of experience of donation for education to improve the teaching efficacy of pre-technology teacher. The Invention experience of donation for education was performed with Invent-touring sponsored by Chunnam National University Invention Education Center for Teachers and was included by development of creative problem solving program, program execution and evaluation. Research participants were Technology education Majors and minors 20 students. The active locations were D children community center, K alternative school, D Elementary School and D middle school. For the study, various literature researches were reviewed intensively about donation for education and teaching efficacy. The instrument for the study was the modified STEBI(Science Teaching Efficacy Beliefs Instrument) for technology education by 3 experts. This study was designed by single group pre and post test design (One-Group Pretest-Posttest Design) and was conducted by the pre-test and post-test. Check the reliability of the tool was conducted with Cronbach ${\alpha}$ coefficient analysis, pre-test 0.840, post-test 0.746. The analysis of data from the 5% significance level, paired sample t-test was performed using the SPSS 19.0 statistical tool. The results were as follows: 1. Teaching efficacy of pre-technology teachers who participated in the invention experience for educational donation technology has improved. 72. The qualitative study was performed by the interviews with students who participated in. Humanism was positively change and learning opportunity was provided to develop the competence of technology education teacher. Based upon the conclusion of this study, the donation activity for invention education need to use learning strategies for pre-technology teacher to improve teaching efficacy.

Analysis Model for Approximate Evaluation of Stiffness for Semi-Rigid Connection of Wooden Structures (목조 구조물 접합부의 강성에 대한 근사평가를 위한 해석모델)

  • Cho, So-Hoon;Lee, Heon-Woo;Park, Moon-Jae;Kim, Taejin;Kim, Jong-Ho
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.28 no.1
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    • pp.93-100
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    • 2015
  • Modern wooden structures usually are connected with steel fastener type connectors. And joints using multiple connectors in wooden structures will form semi-rigid connection. If connection in wooden structure would be designed to be pinned joint, the underestimate for loads transmitted through connection, would result in the deficient capacity of resistance in connection. And if joints in wooden structures would be assumed to be fully-rigid joint, amount of fasteners needed at the connection could be excessively increased. It will give a bad effect in the view of beauty, constructability and economy. Estimate for the reasonable stiffness of connection might be essential in design of reasonable connection in wooden structure. This paper will suggest analysis modelling technique that can represent approximate stiffness of connections using a common analysis program for double shear connection in order to give help in performing easily the design of wooden structure. It is verified that the suggested approximate analysis modelling technique could represent the behavior in connection by comparing the analysis results with test results for tensile, bending moment.

Consumer Awareness and Evaluation of Retailers' Social Responsibility: An Exploratory Approach into Ethical Purchase Behavior from a U.S Perspective (소비자인지도화령수상사회책임(消费者认知度和零售商社会责任): 종미국시각출발적도덕구매행위적탐색성연구(从美国视角出发的道德购买行为的探索性研究))

  • Lee, Min-Young;Jackson, Vanessa P.
    • Journal of Global Scholars of Marketing Science
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    • v.20 no.1
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    • pp.49-58
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    • 2010
  • Corporate social responsibility has become a very important issue for researchers (Greenfield, 2004; Maignan & Ralston, 2002; McWilliams et al., 2006; Pearce & Doh 2005), and many consider it necessary for businesses to define their role in society and apply social and ethical standards to their businesses (Lichtenstein et al., 2004). As a result, a significant number of retailers have adopted CSR as a strategic tool to promote their businesses. To this end, this study sought to discover U.S. consumers' attitudes and behavior in ethical purchasing and consumption based on their subjective perception and evaluation of a retailer. The objectives of this study include: 1) determine the participants awareness of retailers corporate social responsibility; 2) assess how participants evaluate retailers corporate social responsibility; 3) examine whether participants evaluation process of retailers CSR influence their attitude toward the retailer; and 4) assess if participants attitude toward the retailers CSR influence their purchase behavior. This study does not focus on actual retailers' CSR performance because a consumer's decision making process is based on an individual assessment not an actual fact. This study examines US college students' awareness and evaluations of retailers' corporate social responsibility (CSR). Fifty six college students at a major Southeastern university participated in the study. The age of the participants ranged from 18 to 26 years old. Content analysis was conducted with open coding and focused coding. Over 100 single-spaced pages of written responses were collected and analyzed. Two steps of coding (i.e., open coding and focused coding) were conducted (Esterberg, 2002). Coding results and analytic memos were used to understand participants' awareness of CSR and their ethical purchasing behavior supported through the selection and inclusion of direct quotes that were extracted from the written responses. Names used here are pseudonyms to protect confidentiality of participants. Participants were asked to write about retailers, their aware-ness of CSR issues, and to evaluate a retailer's CSR performance. A majority (n = 28) of respondents indicated their awareness of CSR but have not felt the need to act on this issue. Few (n=8) indicated that they are aware of this issue but not greatly concerned. Findings suggest that when college students evaluate retailers' CSR performance, they use three dimensions of CSR: employee support, community support, and environmental support. Employee treatment and support were found as an important criterion in evaluation of retailers' CSR. Respondents indicated that their good experience with a retailer as an employee made them have a positive perception and attitude toward the retailer. Regarding employee support four themes emerged: employee rewards and incentives based on performance, working environment, employee education and training program, and employee and family discounts. Well organized rewards and incentives were mentioned as an important attribute. The factors related to the working environment included: how well retailers follow the rules related to working hours, lunch time and breaks was also one of the most mentioned attributes. Regarding community support, three themes emerged: contributing a percentage of sales to the local community, financial contribution to charity organizations, and events for community support. Regarding environments, two themes emerged: recycling and selling organic or green products. It was mentioned in the responses that retailers are trying to do what they can to be environmentally friendly. One respondent mentioned that the company is creating stores that have an environmentally friendly design. Information about what the company does to help the environment can easily be found on the company’s website as well. Respondents have also noticed that the stores are starting to offer products that are organic and environmentally friendly. A retailer was also mentioned by a respondent in this category in reference to how the company uses eco-friendly cups and how they are helping to rebuild homes in New Orleans. The respondents noticed that a retailer offers reusable bags for their consumers to purchase. One respondent stated that a retailer uses its products to help the environment, through offering organic cotton. After thorough analysis of responses, we found that a participant's evaluation of a retailers' CSR influenced their attitudes towards retailers. However, there was a significant gap between attitudes and purchasing behavior. Although the participants had positive attitudes toward retailers CSR, the lack of funds and time influenced their purchase behavior. Overall, half (n=28) of the respondents mentioned that CSR performance affects their purchasing decisions making when shopping. Findings from this study provide support for retailers to consider their corporate social responsibility when developing their image with the consumer. This study implied that consumers evaluate retailers based on employee, community and environmental support. The evaluation, attitude and purchase behavior of consumers seem to be intertwined. That is, evaluation is based on the knowledge the consumer has of the retailers CSR. That knowledge may influence their attitude toward the retailer and thus influence their purchase behavior. Participants also indicated that having CSR makes them think highly of the retailer, but it does not influence their purchase behavior. Price and convenience seem to surpass the importance of CSR among the participants. Implications, recommendations for future research, and limitations of the study are also discussed.