• Steel and Composite Structures
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• 제43권5호
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• pp.581-601
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• 2022

The main objective of this research work is to investigate the free vibration behavior of annular sandwich plates resting on the Kerr foundation at thermal conditions. This sandwich configuration is composed of two FGM face sheets as coating layer and a porous GPLRC (GPL reinforced composite) core. It is supposed that the GPL nanofillers and the porosity coefficient vary continuously along the core thickness direction. To model closed-cell FG porous material reinforced with GPLs, Halpin-Tsai micromechanical modeling in conjunction with Gaussian-Random field scheme is used, while the Poisson's ratio and density are computed by the rule of mixtures. Besides, the material properties of two FGM face sheets change continuously through the thickness according to the power-law distribution. To capture fundamental frequencies of the annular sandwich plate resting on the Kerr foundation in a thermal environment, the analysis procedure is with the aid of Reddy's shear-deformation plate theory based high-order shear deformation plate theory (HSDT) to derive and solve the equations of motion and boundary conditions. The governing equations together with related boundary conditions are discretized using the generalized differential quadrature (GDQ) method in the spatial domain. Numerical results are compared with those published in the literature to examine the accuracy and validity of the present approach. A parametric solution for temperature variation across the thickness of the sandwich plate is employed taking into account the thermal conductivity, the inhomogeneity parameter, and the sandwich schemes. The numerical results indicate the influence of volume fraction index, GPLs volume fraction, porosity coefficient, three independent coefficients of Kerr elastic foundation, and temperature difference on the free vibration behavior of annular sandwich plate. This study provides essential information to engineers seeking innovative ways to promote composite structures in a practical way.

• 실천공학교육논문지
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• 제14권1호
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• pp.75-83
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• 2022

파이썬 프로그래밍 언어를 강의하는 과목은, 일반 대학에서 모든 재학생이 필수로 이수하는 교양 과목으로 대부분 운영되고 있다. 이를 통해, 컴퓨팅 사고에 의한 기초 프로그래밍 과정을 학습한 비전공자 학생들이 다양한 전공 분야에서 SW를 적용할 수 있는 융합 역량을 강화하고 있다. 기존 연구결과에서는 컴퓨팅 사고 개념 이해와 코드 작성 역량에 대한 다양한 평가 방법들이 제시되었다. 그러나, 평가 문제 사례는 제시되지 않아, 실제 과목 운영 시 적용하는 데 어려움이 있다. 이에 본 논문에서는 비전공자들을 위한 교양과목으로 적용할 수 있는 파이썬 기초 프로그래밍 커리큘럼을 ADDIE 모형에 따라 제안하였다. 그리고 제안된 상세 커리큘럼에 따른 파이썬 요소별 평가 문제 사례를 1차와 2차로 나누어 제안하였다. 마지막으로 본 평가 문제 사례를 적용한 강좌에서 산출된 비전공자 학생들의 평가 점수 결과를 바탕으로 제안한 평가 문제의 유효성을 분석하였다. 제안된 평가 문제 사례는 실시간 온라인 비대면 평가 방식으로 적용하여, 효과적으로 비전공자 학생들의 프로그래밍 역량을 평가할 수 있음을 확인하였다.

• Steel and Composite Structures
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• 제48권3호
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• pp.275-291
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• 2023

This paper has focused on presenting vibration analysis of trapezoidal sandwich plates with 3D-graphene foam reinforced polymer matrix composites (GrF-PMC) core and FG wavy CNT-reinforced face sheets. The porous graphene foam possessing 3D scaffold structures has been introduced into polymers for enhancing the overall stiffness of the composite structure. Also, 3D graphene foams can distribute uniformly or non-uniformly in the plate thickness direction. The effective Young's modulus, mass density and Poisson's ratio are predicted by the rule of mixture. In this study, the classical theory concerning the mechanical efficiency of a matrix embedding finite length fibers has been modified by introducing the tube-to-tube random contact, which explicitly accounts for the progressive reduction of the tubes' effective aspect ratio as the filler content increases. The First-order shear deformation theory of plate is utilized to establish governing partial differential equations and boundary conditions for trapezoidal plate. The governing equations together with related boundary conditions are discretized using a mapping-generalized differential quadrature (GDQ) method in spatial domain. Then natural frequencies of the trapezoidal sandwich plates are obtained using GDQ method. Validity of the current study is evaluated by comparing its numerical results with those available in the literature. It is explicated that 3D-GrF skeleton type and weight fraction, carbon nanotubes (CNTs) waviness and CNT aspect ratio can significantly affect the vibrational behavior of the sandwich structure. The plate's normalized natural frequency decreased and the straight carbon nanotube (w=0) reached the highest frequency by increasing the values of the waviness index (w).

• 한국터널지하공간학회 논문집
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• 제11권3호
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• pp.229-242
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• 2009

본 논문에서는 터널굴착으로 발생한 지표면에서의 최대 침하 및 수평변위와 총 침하부피량을 추정하기 위하여 서로 상이한 지층에서 다양한 깊이 및 직경, 서로 다른 시공조건(지반손실량)을 가진 터널에 대해 수치해석을 수행하였다. 수치해석 결과로부터 얻어진 지표면에서의 최대 침하량은 터널 굴착부 천단에서의 최대 침하량과 지층별, 터널직경 및 깊이, 시공조건(지반손실량)별로 비교되었으며, 또한 지표면에서의 최대 침하량은 지표면에서의 최대 수평변위량과도 비교하였다. 뿐만 아니라, 터널굴착부에서 발생한 지반손실량($V_L$)과 지표면에서 형성된 총 침하부피량($V_s$)을 지층 및 터널깊이와 직경을 달리하여 상호 비교하였다. 수치해석을 통해 얻어진 결과는 그 적용성과 타당성을 검증하기 위하여 기존 현장계측자료와의 비교가 수행되었으며, 이를 통해 본 연구의 수치해석 결과가 향후 터널굴착으로 발생된 주변 지반의 거동을 파악하고 분석하는 실무자료로서 활용될 수 있다는 것을 파악하였다.

• 한국식생활문화학회지
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• 제39권1호
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• pp.13-29
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• 2024

A checklist of dietary behavior items for the elderly was developed based on Korean dietary guidelines. First, a literature review was conducted, and 63 preliminary items, including 30 items on food intake, 12 on eating habits, and 21 on dietary culture, were obtained to evaluate the dietary guidelines. The preliminary items were evaluated by experts using Lawshe's method to verify the content validity. They were then revised, resulting in 52 items: 25, 11, and 16 in the food intake, eating habits, and dietary culture domains, respectively. A face-to-face survey was conducted on 331 people over 65 years of age in the metropolitan area, and their one-day food intake was surveyed using a 24-hour recall method in August 2022. The 48 items, including 24, 11, and 13 items on food intake, eating habits, and dietary culture, respectively, correlated significantly with the evaluation indicators of nutrient intake, such as mean adequacy ratio, dietary diversity score, and nutrient intake density. These items were considered suitable for evaluating the elderly's compliance with dietary guidelines.

• Steel and Composite Structures
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• 제51권1호
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• pp.73-91
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• 2024

This paper has focused on presenting vibration analysis of trapezoidal sandwich plates with a damaged core and FG wavy CNT-reinforced face sheets. A damage model is introduced to provide an analytical description of an irreversible rheological process that causes the decay of the mechanical properties, in terms of engineering constants. An isotropic damage is considered for the core of the sandwich structure. The classical theory concerning the mechanical efficiency of a matrix embedding finite length fibers has been modified by introducing the tube-to-tube random contact, which explicitly accounts for the progressive reduction of the tubes' effective aspect ratio as the filler content increases. The First-order shear deformation theory of plate is utilized to establish governing partial differential equations and boundary conditions for the trapezoidal plate. The governing equations together with related boundary conditions are discretized using a mapping-generalized differential quadrature (GDQ) method in spatial domain. Then natural frequencies of the trapezoidal sandwich plates are obtained using GDQ method. Validity of the current study is evaluated by comparing its numerical results with those available in the literature. After demonstrating the convergence and accuracy of the method, different parametric studies for laminated trapezoidal structure including carbon nanotubes waviness (0≤w≤1), CNT aspect ratio (0≤AR≤4000), face sheet to core thickness ratio (0.1 ≤ ${\frac{h_f}{h_c}}$ ≤ 0.5), trapezoidal side angles (30° ≤ α, β ≤ 90°) and damaged parameter (0 ≤ D < 1) are carried out. It is explicated that the damaged core and weight fraction, carbon nanotubes (CNTs) waviness and CNT aspect ratio can significantly affect the vibrational behavior of the sandwich structure. Results show that by increasing the values of waviness index (w), normalized natural frequency of the structure decreases, and the straight CNT (w=0) gives the highest frequency. For an overall comprehension on vibration of laminated trapezoidal plates, some selected vibration mode shapes were graphically represented in this study.

• 대한간호학회지
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• 제36권6호
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• pp.1002-1011
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• 2006

Purpose: The purpose of this study was to determine characteristics of nursing science and identify expected outcomes from baccalaureate graduates, and to develop accreditation standards and criteria reflecting the characteristics of the nursing profession. Methods: A methodological research design was utilized in this study. Related literature reviews and the nursing education program goals and objectives of the 99 nursing schools in Korea were analyzed. A cross-sectional survey research design was utilized to test the validity of the developed characteristics of the nursing profession and their accreditation criteria and standards. The face validity was from the advisory committee and public committee hearing. Results: The characteristics of nursing science were defined with five concepts including humanity, scientific knowledge, professionalism, therapeutic relationship, and facilitating well-being. The expected outcomes from graduates were identified as providing holistic nursing, critical thinking, establishing professionalism and leadership, construction of a therapeutic relationship, and skilled nursing practice. Finally6 standards and 14 criteria reflecting the unique characteristics of the nursing profession were developed for accreditation. These proposed accreditation standards and criteria are a challenge to promote the quality of nursing science.

• 보건교육건강증진학회지
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• 제24권4호
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• pp.41-64
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• 2007

Objectives: The purpose of this study was to verify the validity of the evaluation indicators on safety and health education programs provided to Korean industrial workers, by developing further. Methods: To develop the early evaluation indicator, the secondary analysis was made on 'Survey on Industrial safety & health trends', the national wide survey data product by Korea Occupational Safety & Health Agency, as well as the various examinations on literatures. To validate such developed evaluation indicator, 13 safety and health managers in Focus Group discussion to prove the reliability of the contents were composed. To confirm the face validity, the interview with 6 industrial safety and health education experts was held to study the appropriateness of the content. With the cooperation from Korea Occupational Safety & Health Agency, the structured survey was performed with the safety and health managers from 588 businesses who participated in the education program for the later half of 2006. In this study, the number of responses was randomly divided into 1:1 two groups, in which one group was for the Exploratory Factor Analysis and the other group was for the Confirmatory Factor Analysis. Results: The results were as follows. First, for the Structure category, 18 evaluation indicators were developed into 4 evaluation categories such as a preliminary examination, education staff and organization, education environment and rules/ regulation. Secondly, the Activity category was comprised of 10 evaluation indicators with respect to 2 areas of curriculum satisfaction and program evaluation. Finally, for the Output category, 9 evaluation indicators were developed into 2 evaluation areas such as documentation and information share and education effects. Conclusions: The evaluation indicators developed through this study will possibly develop and be applied to evaluation tools on safety and health education program, which may further become the standardized indicators to better operate the industrial safety and health education programs.

• 대한치과교정학회지
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• 제42권5호
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• pp.235-241
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• 2012

Objective: The purpose of this study was to evaluate the validity of the 3-dimensional (3D) superimposition method of digital models in patients who received treatment with rapid maxillary expansion (RME) and maxillary protraction headgear. Methods: The material consisted of pre- and post-treatment maxillary dental casts and lateral cephalograms of 30 patients, who underwent RME and maxillary protraction headgear treatment. Digital models were superimposed using the palate as a reference area. The movement of the maxillary central incisor and the first molar was measured on superimposed cephalograms and 3D digital models. To determine whether any difference existed between the 2 measuring techniques, intra-class correlation (ICC) and Bland-Altman plots were analyzed. Results: The measurements on the 3D digital models and cephalograms showed a very high correlation in the antero-posterior direction (ICC, 0.956 for central incisor and 0.941 for first molar) and a moderate correlation in the vertical direction (ICC, 0.748 for central incisor and 0.717 for first molar). Conclusions: The 3D model superimposition method using the palate as a reference area is as clinically reliable for assessing antero-posterior tooth movement as cephalometric superimposition, even in cases treated with orthopedic appliances, such as RME and maxillary protraction headgear.

• 임상간호연구
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• 제18권2호
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• pp.317-328
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• 2012

Purpose: This study was done to provide oncology nurses systemic guidelines designed to perform telephone counseling in outpatient settings treating patients with chemotherapy. Methods: Symptoms which are frequently questioned were identified through case reports recorded by 4 clinical nurse specialists from January 4 to December 31. 2010. Fifteen clinical experts and two hemato-oncologists reviewed the developed draft. Their opinions were synthesized to arrive at consensus on the ideal guidelines. This process confirmed content validity. The two hemato-oncologists also verified the face validity. Results: The six symptoms which were most frequently asked about were identified through 4,644 case reports and concerned pain, fever, skin alteration, nausea/vomiting, stomatitis and diarrhea. Evidence-based telephone triage guidelines for the 6 major symptoms in patients receiving chemotherapy were developed. Conclusion: These guidelines will help oncology nurses from novice to expert incorporate evidence-based telenursing into their practice.