• 제목/요약/키워드: essential norm

검색결과 52건 처리시간 0.025초

A POSTERIORI ERROR ESTIMATOR FOR HIERARCHICAL MODELS FOR ELASTIC BODIES WITH THIN DOMAIN

  • Cho, Jin-Rae;J. Tinsley Oden
    • Journal of Theoretical and Applied Mechanics
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    • 제3권1호
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    • pp.16-33
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    • 2002
  • A concept of hierarchical modeling, the newest modeling technology. has been introduced early In 1990. This nu technology has a goat potential to advance the capabilities of current computational mechanics. A first step to Implement this concept is to construct hierarchical models, a family of mathematical models which are sequentially connected by a key parameter of the problem under consideration and have different levels in modeling accuracy, and to investigate characteristics In their numerical simulation aspects. Among representative model problems to explore this concept are elastic structures such as beam-, arch-. plate- and shell-like structures because the mechanical behavior through the thickness can be approximated with sequential accuracy by varying the order of thickness polynomials in the displacement or stress fields. But, in the numerical analysis of hierarchical models, two kinds of errors prevail: the modeling error and the numerical approximation errors. To ensure numerical simulation quality, an accurate estimation of these two errors Is definitely essential. Here, a local a posteriori error estimator for elastic structures with thin domain such as plate- and shell-like structures Is derived using element residuals and flux balancing technique. This method guarantees upper bounds for the global error, and also provides accurate local error Indicators for two types of errors, in the energy norm. Comparing to the classical error estimators using flux averaging technique, this shows considerably reliable and accurate effectivity indices. To illustrate the theoretical results and to verify the validity of the proposed error estimator, representative numerical examples are provided.

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A posteriori error estimator for hierarchical models for elastic bodies with thin domain

  • Cho, Jin-Rae
    • Structural Engineering and Mechanics
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    • 제8권5호
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    • pp.513-529
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    • 1999
  • A concept of hierarchical modeling, the newest modeling technology, has been introduced in early 1990's. This new technology has a great potential to advance the capabilities of current computational mechanics. A first step to implement this concept is to construct hierarchical models, a family of mathematical models sequentially connected by a key parameter of the problem under consideration and have different levels in modeling accuracy, and to investigate characteristics in their numerical simulation aspects. Among representative model problems to explore this concept are elastic structures such as beam-, arch-, plate- and shell-like structures because the mechanical behavior through the thickness can be approximated with sequential accuracy by varying the order of thickness polynomials in the displacement or stress fields. But, in the numerical, analysis of hierarchical models, two kinds of errors prevail, the modeling error and the numerical approximation error. To ensure numerical simulation quality, an accurate estimation of these two errors is definitely essential. Here, a local a posteriori error estimator for elastic structures with thin domain such as plate- and shell-like structures is derived using the element residuals and the flux balancing technique. This method guarantees upper bounds for the global error, and also provides accurate local error indicators for two types of errors, in the energy norm. Compared to the classical error estimators using the flux averaging technique, this shows considerably reliable and accurate effectivity indices. To illustrate the theoretical results and to verify the validity of the proposed error estimator, representative numerical examples are provided.

소아에서 말 언어장애 (Speech and language disorders in children)

  • 정희정
    • Clinical and Experimental Pediatrics
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    • 제51권9호
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    • pp.922-934
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    • 2008
  • Developmental language disorder is the most common developmental disability in childhood, occurring in 5-8% of preschool children. Children learn language in early childhood, and later they use language to learn. Children with language disorders are at increased risk for difficulties with reading and written language when they enter school. These problems often persist through adolescence or adulthood. Early intervention may prevent the more serious consequences of later academic problems, including learning disabilities. A child's performance in specific speech and language areas, such as phonological ability, vocabulary comprehension, and grammatical usage, is measured objectively using the most recently standardized, norm-referenced tests for a particular age group. Observation and qualitative analysis of a child's performance supplement objective test results are essential for making a diagnosis and devising a treatment plan. Emphasis on the team approach system in the evaluation of children with speech and language impairments has been increasing. Evidence-based therapeutic interventions with short-term, long-term, and functional outcome goals should be applied, because there are many examples of controversial practices that have not been validated in large, controlled trials. Following treatment intervention, periodic follow-up monitoring by a doctor is also important. In addition, a systematized national health policy for children with speech and language disorders should be provided.

A Classification of Luxury Fashion Brands' E-commerce Sites

  • Kim, Sunghee
    • 패션비즈니스
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    • 제17권6호
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    • pp.125-140
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    • 2013
  • The aim of this study was to analyze e-commerce sites of luxury fashion brands in order to provide insights on how to enhance online site quality. For the research, forty-eight components of thirty-one luxury fashion brands' e-commerce sites were investigated during October 2013. For the analysis of clustering e-commerce site components and segmenting e-commerce sites of luxury brands, a hierarchical cluster analysis was applied through using the Ward's method and squared Euclidian distance for binary data. Further, Fisher's exact test was applied in order to distinguish three groups of characteristics in the luxury e-commerce sites. These analyses were carried out by SPSS 21. The result indicated that the components of e-commerce sites were grouped into three categories: basic elements, additional elements and elements of building brand identity. These components were categorized by whether their functions were basic and essential or additional and advanced. The other norm of categorization was related to brand identity. Furthermore, the luxury brands' e-commerce sites were segmented into three groups: a group of endeavoring to promote goods, a group of undistinguished performance, and a group of endeavoring to intensify brand identity. In this segmentation, brand identity or promotional aspects were decisive. Overall, luxury brands were trying to convey their traditional strength through their e-commerce sites. In order to achieve this purpose, brand identity or promotional aspects played an important role.

정상교합을 가진 유치열기 아동의 두부방사선 계측학적 연구 (CEPHALOMETRIC ANALYSIS FOR CHILDREN WITH NORMAL OCCLUSION IN THE PRIMARY DENTITION)

  • 서문선;손흥규;백형선;최형준
    • 대한소아치과학회지
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    • 제32권1호
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    • pp.109-118
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    • 2005
  • 소아치과 영역에서 아동의 두부방사선 계측치의 비교분석은 성장과 발육의 평가에 중요하며 부정교합의 조기진단과 치료를 위한 두개 안면부의 형태, 성장 양상을 아는 것에 필수적이다. 이를 위하여 두부방사선 계측학적 표준치가 중요한데 유치열기에 관한 연구는 많지 않으므로 유치열기 정상교합 아동의 표준치를 얻고 과거 연구에서의 계측치와 비교하고자 서울시내 소재의 유아원 아동 중 유치열기의 정상교합을 가진 4세에서 5세 아동으로 본원에 내원한 안모 및 전신 발육 상태가 양호한 아동 46명을 대상으로 측모 두부방사선 계측 사진을 촬영, 분석하여 다음과 같은 결과를 얻었다. 1. 골격성 계측항목에서 각도 계측치는 남녀사이에 유의한 차이가 없고 길이 계측치는 남자가 여자보다 전반적으로 큰 수치를 보였다. 2. SNA는 $81.3^{\circ}$, SNB는 $76.6^{\circ}$, ANB difference는 $4.7^{\circ}$를 나타냈다. 3. Anterior cranial base length에 대한 Mandibular body length의 비율은 남녀모두 0.9:1이었고 Anterior facial height에 대한 Posterior facial height의 백분율은 남자 61.4%, 여자 62.0%를 나타냈다. 4. 치성 계측항목에서는 IMPA는 $84.2^{\circ}$, UA to SN은 $90.8^{\circ}$를 나타냈다. 5. Ricketts의 심미선에 대하여 상순은 2.6mm, 하순은 2.5mm 전방으로 위치하고 있었다.

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자궁암 조기검진행태 예측을 위한 계획된 행동이론과 이성적 행동이론의 적용 (Application of the Theory of Planned Behavior and the Theory of Reasoned Action to Predicting Cervix Cancer Screening Behavior)

  • 김용익;김창엽;신영수;이건세
    • Journal of Preventive Medicine and Public Health
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    • 제34권4호
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    • pp.379-388
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    • 2001
  • Background : Cervix cancer is the most common form of cancer among Korea women. in spite of proof that cervical cancer screening could reduce death rates substantially, the screening rates reported by previous Korean studies remain stubbornly very low. Behavioral studies to increase the cervix cancer screening rate are essential in order to develop the cancer screening program. Objective : To evaluate the factors which are related to the intention and behavior for cervix cancer screening using the Theory of Planned Behavior (TPB) and the Theory of Reasoned Action (TRA). Methods : The survey was conducted from July 21 st to 26th in 1998. Of 3,218 women, 303(12.2%) between 30 and 55 years old, voluntarily participated in the survey in the 3 Myeons in Choongju city. Charge-free cervix cancer screening was provided for the subjects 3 months later. Results : The R-square of both TPB and TRA to the intention (30% and 42%, respectively) was greater than the actual behavior (21% and 13%, respectively. TPB and TRA were found to provide an appropriate framework for the study of cervix cancer screening behavior. However, TRA was more powerful in explaining the intention, not only because the perceived behavioral control component exhibited lower reliability and validity than other components(altitude and subjective norm), but also because there may have been a few limitations in this study design. Consequently, the use of TRA is preferred in attempting to explain intention and actual behavior in this study. Conclusions : This study suggests that a successful intervention program should focus on changing attitudes and reducing psychologic barriers, rather than on just providing information. Physician recommendations, and the support of family members and friends are also very important factors in cervix cancer program participation. Physicians, friends, family members, and opinion leaders in rural areas, all of whom could affect the individual subjective norm, may all have the potential to play great roles as facilitators.

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터널 한계상태설계법 관련 연구 및 적용 동향 (Limit states design for tunnels: related researches and present state of application)

  • 김홍문;김동국;이상덕
    • 한국터널지하공간학회 논문집
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    • 제16권3호
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    • pp.341-346
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    • 2014
  • 대표적인 한계상태설계법은 AASHTO LRFD와 Eurocodes가 있으며, 토목구조물 설계에 폭넓게 적용되고 있다. 그러나 이러한 설계법이 터널설계에 적용될 경우에는 NATM 터널의 라이닝설계와 쉴드터널의 세그먼트 설계에만 제한적으로 적용되고 있다. 최근 유럽에서는 유로코드를 터널설계 전분야에 적용하기 위하여 기준개정(EG12)을 추진하였으나 다른 유로코드(EC2 및 EC3)에 미치는 영향 등을 고려하여 불가피하게 구성하지 않는 것으로 결정되었다. 그러나 여전히 한계상태설계법을 터널설계에 적용하기 위한 연구를 활발히 진행하고 있다. 한계상태설계법은 가까운 장래에 터널을 포함한 토목구조물 설계법의 주류가 될 것이다. 그러므로 Eurocode 7 등 국외 한계상태설계법에 대한 충분한 이해가 중요하며, 국제적인 연구동향을 파악하고 터널설계에 적용하기 위한 연구가 필요하다.

출입문 측면 활동공간 설치기준 개선에 관한 연구 (A Study on Improvement of the Standards for the Manoeuvring space at Doors)

  • 신동홍;박광재
    • 의료ㆍ복지 건축 : 한국의료복지건축학회 논문집
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    • 제25권4호
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    • pp.71-79
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    • 2019
  • Purpose: The manoeuvring space at doors must be secured for users of walking aids, wheelchair users, stroller users, luggage carriers, etc., so clear criteria must be established. The korean standards for the manoeuvring space at doors need to be improved to present clear criteria depending on the type of entrance and the direction of opening and closing. Method: Korean standard, International Standard(ISO 21542, 2011), German Standard(DIN 18040-1, 2010), Austrian Standard(OENORM B 1600, 2017) and Swiss Standard(Norm SIA 500, 2009) were investigated and analyzed. A comprehensive improvement of the criteria for the manoeuvring space at doors is proposed. Results: The manoeuvring space at doors, which is essential for the disabled to use the door, shall be installed with a comprehensive consideration of the width of doors, the Circulation space, the direction of access, and the method of opening and closing of the door. Korean standards, such as the width of doors, the Circulation space, and the manoeuvring space at doors, are different from international and international standards, which require improvement of standards. The criteria for the manoeuvring space at doors shall be clearly improved so as not to be misinterpreted during the installation of doors and the BF-certification. Implication: The criteria for the installation of doors shall be presented as a comprehensive alternative through continued study of details. In addition, improvements in standards that reflect changes in international standards should be made.

캉길렘의 생명철학에서 개체성과 내재적 규범의 문제 (The Problem of Individuality and Intrinsic Norms in Canguilhem's Philosophy of Life)

  • 황수영
    • 의철학연구
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    • 제15권
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    • pp.3-37
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    • 2013
  • 조르주 캉길렘의 의철학에서 의학은 기술이라고 주장된다. 이는 실용적 의미가 아니라 인간의 전체성을 반영하는 가치론적 지평에서 제시된다. 이러한 의학의 특징이 캉길렘의 철학적 사유의 동기가 된다. 의학적 지식은 생리학의 단순한 응용이 아니라 환자 개인의 체험에 기초한 임상적 관찰에서 비롯한다. 의학이 과학이고 그 실행이 순수 지식의 응용이라면 환자는 수동적 대상에 머물게 된다. 그러나 환자는 질병에 수동적으로 노출되기보다는 자신의 생애를 통해 이미 습득된 능동적 태도에 의해 질병의 위협에 대처한다. 캉길렘은 이 점을 '규범성'이라고 특징짓는다. 규범성은 개인의 삶의 핵심이지만 실증주의 의학은 이를 설명할 수 없다. 여기서 캉길렘의 의학사상의 생기론적 특징이 나타난다. 캉길렘의 규범성 개념은 일인칭 주관과 관련되기 때문에 기계론적 설명방식을 벗어난다. 캉길렘의 독창성은 개체성과 가치 그리고 규범에서 의학의 본질을 도출하는 데 있다.

고령층의 키오스크 사용에서의 기술스트레스와 주관적 규범이 그림자노동 지각에 미치는 영향: 실증 분석 (Kiosk Use Among Seniors: An Empirical Investigation of the Effects of Technostress and Subjective Norms on Awareness of Shadow Work)

  • 지도성;고준
    • 정보화정책
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    • 제30권4호
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    • pp.62-88
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    • 2023
  • 키오스크 도입은 인건비 절감 효과를 누리면서 일상생활의 필수요소로 자리매김하고 있지만, 디지털 격차에 따른 고령층 등 약자에 대한 사회문제도 야기해 왔다. 본 연구는 고령층의 셀프서비스 키오스크 사용 중에 발생하는 심리적 경험인 그림자노동 지각 관점에서 키오스크 사용갈등에 연관성이 높은 요인들을 파악하고자 하였다. 고령층 159명의 설문 분석 결과, 고령층 이용자의 기술스트레스 및 주관적 규범은 사용갈등과 유의한 연관성이 있음을 밝혔으며, 그림자노동 지각정도는 이들 관계에서 부분 매개효과를 가지고 있었다. 또한 사용경험은 기술스트레스의 그림자노동지각에 대한 관계를 완화시키는 조절효과를 보였다. 본 연구의 결과는 고령층의 디지털 그림자노동 이슈에 대한 이해를 높이고, 디지털 기술 배려 및 디지털 포용 관점에서 연구적 시사점을 제공한다.