• Title/Summary/Keyword: critical criteria

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Tunnel Safety Assessment by using the Concept of the Critical Strain in the Ground (한계변형률 개념을 활용한 터널안전성 평가)

  • Park, Si-Hyun;Park, Sung-Kun
    • Proceedings of the Korean Geotechical Society Conference
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    • 2010.03a
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    • pp.571-576
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    • 2010
  • In this study, an application method of critical strains concept for tunnels' safety by using the values of measured displacements which are obtained in the field is discussed. The aim is to: (1) study on the engineering meanings of critical strains concept by reviewing the previous researches and application examples with measured displacement values; (2) study on the engineering reasonability of critical strains concept with the view point of a tunnel engineering and a geotechnical engineering; (3) study on the features of ground deformation due to tunneling and reciprocal relation between total displacement and measured displacement; (4) evaluate a tunnel safety by using domestic measurements collected in the field; and (5) re-evaluate the control criteria which were previously used in the field, with the view point of critical strains concept. Consequently, it was confirmed that critical strains in the ground has a reasonability and a possibility of unified or common concept with the view point of a tunnel engineering.

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A study on critical strain based damage-controlled test for the evaluation of rock tunnel stability (암반터널 안정성 평가를 위한 손상제어실험 기반의 한계변형률에 관한 연구)

  • Lee, Kang-Hyun;Kim, Do-Hoon;Park, Jeong-Jun;Lee, In-Mo
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.13 no.6
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    • pp.501-517
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    • 2011
  • In general, the tunnel stability during excavation is assessed by comparing measured displacements at roof and sidewall to control criteria. The control criteria were established based on the past experience that considered ground conditions, size of the tunnel cross section, construction method, supports, etc. Therefore, a number of researches on the control criteria using the critical strain have been conducted. However, the critical strain obtained from uniaxial compression tests have drawbacks of not taking damage in rock mass due to increase of stress level and longitudinal arching into account. In this paper, damage-controlled tests simulating stress level and longitudinal arching during tunnel excavation were carried out in addition to uniaxial compression tests to investigate the critical strain characteristics of granite and gneiss that are most abundant rock types in Korean peninsula. Then, the critical strains obtained from damage-controlled tests were compared to those from uniaxial compression tests; the former showed less values than the latter. These results show that the critical strain obtained from uniaxial compression tests has to be reduced a little bit to take stress history during tunnel excavation into account. Moreover, the damage critical strain was proposed to be used for assessment of the brittle failure that usually occurs in deep tunnels.

A Study on the Selective Criteria and Information Soruce of Imported Apparel Brand (해외의류상표 도입시 선택기준과 정보탐색 행동)

  • 권영아
    • Journal of the Korean Society of Costume
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    • v.47
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    • pp.101-112
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    • 1999
  • This study examined 1) retail buyer's reasons for buying imported apparel and brand license business and 2) types of information sources which they searched for the businesses 3) types of product/vendor selective criteria Seventy subjects of one hundred samples responded. They were designers merchandisers of apparel companies and buyers of department stores. The results of empirical studies were summarized as follows: 1) Buyers & merchandisers recognized domestic market responses as the most important information source for selecting foreign brand. The critical problem of buying and brand license was deficiency of professionals in fashion retail 2) Buyers & merchandisers primarily recognized brand identity and exclusive style of the product when selecting puoduct or vendor. 3) Buyers & merchandisers primarily recognized return policy and good delivery of the vendor when selecting vendor 4). There were relationships among incormation sources selective criteria of product/vendor and buyer's characteristics.

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Application of Multi-criteria Decision Making Techniques for Water Resources Planning: 2. Sensitivity Analysis of Weighting and Performance Values (수자원 계획수립을 위한 다기준의사결정기법의 적용: 2. 가중치와 평가치에 대한 민감도 분석)

  • Chung, Eun-Sung
    • Journal of Korea Water Resources Association
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    • v.45 no.4
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    • pp.383-391
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    • 2012
  • This study aims to present the sensitivity analysis approach for multi-criteria decision making (MCDM) method to reduce the uncertainty of weighting and performance values. This study focuses on two major problems of the uncertainty for MCDM method. The first major problem is how to determine the most critical criterion and the second is how to determine the most critical measure of performance. This study used the application of weighted sum method for water resources planning. The criticality degrees and the sensitivity coefficients of criterion and alternative are used. This results of sensitivity analysis can be applied to the general water resources planning in real.

Study on the fatigue crack initiation life in rail wheel contact (철도차량용 휠과 레일의 피로균열시작 수명에 관한 연구)

  • 김태완;설광조;조용주
    • Proceedings of the KSR Conference
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    • 2002.10a
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    • pp.733-738
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    • 2002
  • In this study, contact fatigue in wheel-rail contact is simulated. It is necessary to calculate contact stress and subsurface stresses accurately to predict fatigue behavior. Contact stresses are obtained by contact analysis of semi-infinite solid based on influence function and subsurface stress field obtained by using rectangular patch solutions. Based on these stress values, several multiaxial high-cycle fatigue criteria are used and the critical loads corresponding to fatigue limits are calculated. The simulation results show that the critical load is decreasing rapidly and the site of crack initiation also moves rapidly to the surface from the subsurface when friction coefficient exceeds a specific value for all of three fatigue criteria.

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A Critical Examination of Recent Studies On the Definition of Services (서비스 개념을 둘러싼 최근논의에 대한 비판적 고찰)

  • Seo, Hwan-Joo
    • Journal of Information Technology Services
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    • v.7 no.4
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    • pp.287-300
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    • 2008
  • Our Study aims to examine, from a critical perspective, recent approaches to the definition of services, Studies that deal with the question of how to characterize services offer three types of response. The first approach developed by classical economists proposes to use technical criteria (immateriality, non-separability between consumption and production, non-storage, heterogeneity) as foundation for a specific definition of services. The second, which is today most widely cited definition, that of Peter Hill proposes an institutional or a relation-oriented definition which emphasizes service triangle. Finally, the work of Gadrey, which investigates the impact of new technologies on service activities, offers a new general definition of services that is compatible with the existence of several demand rationales.

Development and Validation of a Behaviorally Anchored Rating Scale for Peer Evaluation in Group Projects (조별 과제 동료평가 행동기준평정척도 개발 및 타당화 연구)

  • Shin, Tae Seob
    • Journal of Engineering Education Research
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    • v.21 no.5
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    • pp.32-39
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    • 2018
  • The purpose of this study was to develop and validate a behaviorally anchored rating scale for peer evaluation in group projects based on social interdependence theory. A mixed method involving a qualitative and quantitative approach was used in this study. In the qualitative study, both the individual and group interviews were conducted to college students regarding their cooperative learning experiences. Data from this qualitative research was analyzed based on 5 elements of cooperative learning and 'critical incidents' were extracted from students' own voices that would serve as specific rating criteria in the scale. Once the 'critical incidents' have been incorporated into the scale, validation from 3 independent experts was conducted. In the quantitative study, correlations with relevant variables were analyzed to examine the criteria-referenced validity. Findings suggest that the behaviorally anchored rating scale for peer evaluation in group projects can be used in various team-based learning contexts.

Development of the assessment method for weekly groundwater resources management vulnerability using the correlation between groundwater level and precipitation considering critical infiltration concept (한계 침투량을 고려한 강우와 지하수위의 상관관계를 이용한 주 단위 지하수자원 관리 취약시기 평가 방법 개발)

  • Lee, Jae-Beom;Yang, Jeong-Seok;Kim, Il-Hwan
    • Journal of Korea Water Resources Association
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    • v.51 no.12
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    • pp.1237-1245
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    • 2018
  • We developed the assessment method for weekly groundwater resources management vulnerability. To consider the effect of precipitation on groundwater level, we calculated correlation coefficient between groundwater level and precipitation applying critical infiltration concept. We developed the vulnerability assessment criteria and calculated weights for criteria using the entropy method. Weekly groundwater resources management vulnerability of small administrative districts were estimated using developed method in this research. The developed method can be a basis for the establishment of the spatio-temporal groundwater resources management plan.

The Roles of Critical Care Advanced Practice Nurse

  • Sung, Young-Hee;Yi, Young-Hee;Kwon, In-Gak;Cho, Yang-Ae
    • Journal of Korean Academy of Nursing
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    • v.36 no.8
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    • pp.1340-1351
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    • 2006
  • Purpose. To determine and compare the perception among nurses and doctors of the roles and tasks of critical care advanced practice nurses (APNs) in order to establish standardized and formally agreed role criteria for such critical care APNs. Method. This study measured and analyzed the necessity of each of the roles and tasks of critical care APNs, as perceived by nurses and doctors, through a survey of 121 participants: 71 nurses in 7 intensive care units (ICUs) at a general hospital in Seoul, and 50 doctors who used ICUs. Data collection utilized a questionnaire of 128 questions in the following fields: direct practice (79), leadership and change agent (17), consultation and collaboration (15), education and counseling (11), and research (6). Results. Both the nurses' and the doctors' groups confirmed the necessity of critical care APNs, with doctors who frequently used ICUs indicating a particularly strong need. As for the priority of each role of critical care APNs, the nurses considered direct practice to be the most critical, followed by education and counseling, research, consultation and collaboration, and leadership and change agent. The doctors also considered direct practice to be the most critical, followed by education and counseling, consultation and collaboration, research, and leadership and change agent. There was a statistically significant difference between how the two groups regarded all the roles, except for the consultation and collaboration roles. As for the necessity of each role of critical care APNs, the nurses considered research to be the most necessary, followed by education and counseling, consultation and collaboration, leadership and change agent, and direct practice. The doctors, on the other hand, considered education and counseling to be the most necessary, followed by research, consultation and collaboration, leadership and change agent, and direct practice. The responses of the two groups to all the roles, except for education and counseling roles, were significantly different. Conclusion. Nurses and doctors have different perceptions of the roles and tasks of critical care APNs. Thus, it is necessary for the combined nursing and medical fields to reach an official agreement on a set of criteria to standardize for the roles and tasks of critical care APNs.