• 제목/요약/키워드: critical criteria

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

  • 박시현;박성근
    • 한국지반공학회:학술대회논문집
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    • 한국지반공학회 2010년도 춘계 학술발표회
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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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암반터널 안정성 평가를 위한 손상제어실험 기반의 한계변형률에 관한 연구 (A study on critical strain based damage-controlled test for the evaluation of rock tunnel stability)

  • 이강현;김도훈;박정준;이인모
    • 한국터널지하공간학회 논문집
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    • 제13권6호
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    • pp.501-517
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    • 2011
  • 일반적으로 터널 시공현장에서는 계측된 천단 및 내공변위와 계측관리기준을 비교하여 터널의 안정성을 판단한다. 현재 계측관리기준은 지반조건, 터널단면의 크기, 시공방법, 지보재량 등을 고려한 경험을 통해 세워지고 있는 실정이다. 따라서 새로운 계측관리기준으로 한계변형률을 이용하는 방법에 대한 연구가 다수 수행되었다. 그러나 대부분의 연구는 일축압축강도실험에서 얻어진 한계변형률을 기준으로 삼고 있어 실제 터널 굴착 시 발생하는 응력의 증가 및 종방향 아칭에 의한 암반 손상을 고려하지 않는 문제점을 가지고 있다. 따라서 본 연구에서는 국내 대표 암종인 화강암과 편마암의 한계변형률 특성을 조사하기 위하여 일축압축강도실험과 응력의 증가 및 종방향 아칭을 고려한 손상제어실험을 수행하였다. 손상제어실험에서 얻어진 한계변형률은 일축압축강도실험에서 얻어진 한계변형률보다 다소 작게 나타났다. 이는 일축압축강도실험에서 얻은 한계변형률은 터널 굴착 시의 응력이력을 고려하여 다소 감소시켜야 한다는 것을 의미한다. 또한 대심도 터널에서 흔히 발생하는 취성파괴를 평가하기 위한 손상한계변형률을 제안하였다.

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

  • 권영아
    • 복식
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    • 제47권
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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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수자원 계획수립을 위한 다기준의사결정기법의 적용: 2. 가중치와 평가치에 대한 민감도 분석 (Application of Multi-criteria Decision Making Techniques for Water Resources Planning: 2. Sensitivity Analysis of Weighting and Performance Values)

  • 정은성
    • 한국수자원학회논문집
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    • 제45권4호
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    • pp.383-391
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    • 2012
  • 본 연구는 다기준 의사결정 문제에서 항상 발생하는 가중치와 대안들의 평가치에 대한 불확실성을 최소화하기 위해 민감도 분석을 수행하는 절차를 제시하였다. 제기되는 가중치에 대한 불확실성을 극복하기 위해 일반적으로 순위가 뒤바뀔 수 있는 가장 민감한 평가기준의 결정과 대안의 효과 측정자료의 결정이 있다. 본 연구는 유량확보와 수질개선을 위한 수자원 계획수립을 위해가중합계법을 이용한 문제에 두 경우의 민감도분석을 모두수행하였다. 이 과정에서 결정계수와 민감도 계수를 산정하여 이용하였다. 본 연구에서 제시한 민감도 분석 과정은 향후 수자원 계획 수립에 폭넓게 활용될 수 있다.

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

  • 김태완;설광조;조용주
    • 한국철도학회:학술대회논문집
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    • 한국철도학회 2002년도 추계학술대회 논문집(I)
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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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서비스 개념을 둘러싼 최근논의에 대한 비판적 고찰 (A Critical Examination of Recent Studies On the Definition of Services)

  • 서환주
    • 한국IT서비스학회지
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    • 제7권4호
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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.

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

  • 신태섭
    • 공학교육연구
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    • 제21권5호
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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.

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

  • 이재범;양정석;김일환
    • 한국수자원학회논문집
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    • 제51권12호
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    • pp.1237-1245
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    • 2018
  • 본 연구에서는 주 단위 지하수자원 관리 취약시기 평가 방법을 개발하였다. 강수의 지하수위에 대한 영향을 고려하기 위하여 한계 침투량을 고려한 강우이동평균 방법을 통해 지하수위와의 상관계수를 산정하였다. 취약 시기 평가 기준을 개발하고 평가 기준에 대한 가중치를 엔트로피 방법을 이용하여 산정하였다. 강수와의 상관계수와 산정된 가중치를 이용한 주 단위 지하수자원 관리 취약시기 평가 방법을 개발하였으며, 개발한 방법을 통하여 소규모 행정구역을 대상으로 취약시기를 평가하였다. 본 연구에서 개발된 방법은 지역적일뿐만 아니라 계절적인 지하수자원의 효율적 관리 대책 수립의 근거가 될 수 있을 것이다.

The Roles of Critical Care Advanced Practice Nurse

  • Sung, Young-Hee;Yi, Young-Hee;Kwon, In-Gak;Cho, Yang-Ae
    • 대한간호학회지
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    • 제36권8호
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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.