• 한국정보과학회논문지:시스템및이론
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• 제36권2호
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• pp.94-101
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• 2009

본 논문에서는 거리 확인 및 공유 키 기반의 challenge-response를 통하여 사용자를 인증하는 인증 시스템을 제안한다. 인증장치는 전파와 초음파 신호의 도달시간의 차를 이용하여 사용자가 소유한 인중토큰이 유효 거리 이내에 있는지 확인하는 동시에, 인증장치가 송신한 challenge에 대해 인증토큰이 키를 기반으로 정확한 응답을 보내는지를 확인한다. 본 논문에서는 이와 같은 인증시스템을 실제로 구현하고 인증장치와 인증토큰의 초음파 센서 방향과 위치의 변화에 따른 인증 성공률을 분석하였다. 실험 결과에 따르면 인증장치와 인증토큰의 방향이 크게 어긋나 있지 않은 상황에서는 대부분 100%에 가까운 인증 성공률을 보임을 확인할 수 있었다.

• 한국추진공학회지
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• 제8권2호
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• pp.73-84
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• 2004

로켓모터의 성능을 확인하기 위해 지상에서 연소시험을 수행하여 추력, 압력, 온도. 그리고 변형률 등 필요한 데이터를 계측하지만 측정된 추력은 시험대 동특성으로 인해 실제 추력과는 달리 과도진동이 포함된 왜곡된 형태를 나타낼 수 있다. 이러한 경우에는 추력 최대치나 추력 상승시간 등 로켓모터의 성능을 결정하는 값들의 정확한 값을 얻지 못할 수 있다. 따라서 본 논문에서는 이러한 추력 왜곡 현상의 원인을 분석하고 그 문제점을 해결하기 위한 이론적인 방법을 제안한다. 또한 제안된 방법을 가상 시험대에 적용하여 제안한 방법의 적용 가능성을 확인하고, 차후 실험 데이터를 이용한 추력 추정의 기본적인 방향을 제시하고자 한다.

• Structural Engineering and Mechanics
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• 제24권5호
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• pp.543-560
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• 2006

In this paper, first, the equations of motion for a rectangular isotropic plate have been derived. This derivation is based on the Von Karmann theory and the effects of shear deformation have been considered. Introducing an Airy stress function, the equations of motion have been transformed to a nonlinear coupled equation. Using Galerkin method, this equation has been separated into position and time functions. By means of the dimensional analysis, it is shown that the orders of magnitude for nonlinear terms are small with respect to linear terms. The Multiple Scales Method has been applied to the equation of motion in the forced vibration and free vibration cases and closed-form relations for the nonlinear natural frequencies, displacement and frequency response of the plate have been derived. The obtained results in comparison with numerical methods are in good agreements. Using the obtained relation, the effects of initial displacement, thickness and dimensions of the plate on the nonlinear natural frequencies and displacements have been investigated. These results are valid for a special range of the ratio of thickness to dimensions of the plate, which is a characteristic of the Multiple Scales Method. In the forced vibration case, the frequency response equation for the primary resonance condition is calculated and the effects of various parameters on the frequency response of system have been studied.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• 제19권1호
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• pp.28-37
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• 2008

Objectives : This study was conducted in order to examine the reliability and validity of the Children's Color Trails Test (CCTT). The objective of the study was also to provide the Korean normative data for the CCTT. Methods : Normative samples consisted of 766 children and adolescents living in Seoul and aged from 5 to 15 years. Eighty children who were diagnosed with ADHD, based on the DSM-IV criterion, were recruited from Seoul National University Children's Hospital. Among them, 46 ADHD children were receiving medication, while 34 children were drug-free. Results : The scores of the CCTT were significantly correlated with those of the Stroop test. Three factors were extracted through factor analysis-visual tracking and cognitive flexibility, distractibility and susceptibility to interference, and simple attention and impulsivity. The completion time of the CCTT for all children tended to decrease as age increased. There were significant differences in the CCTT scores between the ADHD group receiving medication, the ADHD-drug free group and the normal groups. The CCTT also showed sound test-retest reliability. These results confirmed the reliability and validity of the CCTT. Finally, we provided the Korean normative data for the CCTT. Conclusion : These results suggest that the CCTT is a reliable and valid test, which can be used to assess frontal function related to child psychiatric disorders in Korean children.

• 한국지진공학회논문집
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• 제22권7호
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• pp.401-409
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• 2018

Performance-based seismic evaluation is usually done by considering simplified models for the liquid storage tanks therefore, it is important to validate those simplified models before conducting such evaluation. The purpose of this study is to compare the seismic response results of the FSI (fluid-structure interaction) model and the simplified models for the cylindrical liquid storage tanks and to verify the applicability of the simplified models for estimating failure probability. Seismic analyses were carried out for two types of storage tanks with different aspect ratios (H/D) of 0.45 and 0.86. FSI model represents detailed 3D fluid-structure interaction model and simplified models are modeled as cantilever mass-spring model, frame type mass-spring model and shell type mass-spring model, considering impulsive and convective components. Seismic analyses were performed with modal analysis followed by time history analysis. Analysis results from all the models were verified by comparing with the results calculated by the code and literature. The results from simplified models show good agreement with the ones from detailed FSI model and calculated results from code and literature, confirming that all three types of simplified models are very valid for conducting failure probability analysis of the cylindrical liquid storage tanks.

• 한국간호교육학회지
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• 제13권2호
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• pp.237-245
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• 2007

Purpose: This study was to investigate actual conflicts between newly graduated nurses and preceptors during preceptorship period and the preceptor's core competency related to their conflicts in order to prepare an educational program to develop a preceptor's core competency. Method: A total of 100 questionnaire sheets were collected for data analysis from a valid pair of 94 newly graduated nurses and 94 preceptors. The questionnaire consisted of the preceptor's core competency evaluation tool, and experiences of the conflicts between newly graduated nurses and preceptors. Data was analyzed using SPSS 12.0. Result: Preceptors faced more conflicts than newly graduated nurses, but the former went through conflicts for a shorter time. The conflict-experiencing newly graduated nurses evaluated their preceptor's core competency more excellently than the other's except 'role model'. The conflict-experiencing preceptors evaluated 'learning plan implementation' competency more excellently than the other's. Conclusion: It is advisable to have educational programs and opportunities for increasing preceptor's core competency.

• 한국간호교육학회지
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• 제15권1호
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• pp.89-99
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• 2009

Purpose: The purpose of this study was to describe married female migrants' experiences of health care services and to help nursing researchers, nursing educators, and clinical nurses understand married female migrants' experiences. Method: A conventional content analysis method was utilized. Individual in-depth interviews with 15 married female migrants were conducted. Subject recruitment was performed at a district in Seoul. Results: Ten categories were induced: language barrier, financial burden, insufficient time with a physician, complexity of utilization process, lack of support from peer group, health care providers' discrimination, anxiety regarding lack of information about children's health, health care providers' concerns and efforts to minimize the language barrier, family support, and advanced health care service environment. Conclusion: This study provides basic knowledge regarding married female migrants' experiences related to health care services. Future research should designate and utilize valid instruments to measure the positive and negative experiences and to explore strategies to strengthen the positive features while eliminating the negative ones. Finally, the Korean nursing education curriculum should include cultural competence and knowledge about an ethnic minority's right to health service utilization.

• 대한가정학회지
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• 제49권6호
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• pp.23-37
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• 2011

This research tried to identify how different types of environments related with work-family reconciliation effects the amount of resource exchange between working mothers and their child. In this study, we applied theoretical concepts such as 'Defamiliarization'(rights of mothers to access the work force without any environmental obstacles) and 'Familiarization'(a movement trying to balance work with family and child). This study is an analysis of valid questionnaires filled out by 220 female respondent's who was holding a job and also had children attending elementary, middle, or high school at the time answering the survey questionnaire. Results of this survey are as follows. Mother's attitudes toward familiarization and child's school environments related with defamiliarization had critical effects on mother's perceived resource exchange. And in a further analysis, among the clustered groups of mothers the group which consists of mothers who try to work hardly on both work and family had the highest degree of the resource supplies to their child.

• 한국통신학회논문지
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• 제9권4호
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• pp.170-178
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• 1984

12채널의 TDM/FDM變換時間을 단축시키기 위하여 14點高速DCT와 多相回路를 사용하였다. 이러한 多相回路는 原試型필터를 各채널의 채널 필터로 變換하여 設計되었고 原試型필터에 대하여 分子의 次數는 168次로 對稱性을 갖도록 하였고 分母의 次數는 6次로 하여 CCITT規定을 만족하도록 하였다. 變換에 필요한 곱셈回數는 $0.12267{\times}10^2$ multiplications/sec channel로써 기존의 결과보다 약 15%~40% 단축하였다. 또한 간단한 檢波시스템을 포함하여 PRIME750컴퓨터에 의한 시뮬레이션過程을 거쳐 理論의 타당성이 확인되었다.

• 한국정보처리학회논문지
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• 제5권7호
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• pp.1671-1679
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• 1998

시간지원 데이터베이스는 현실세계에 존재하는 객체에 대한 효율적인 이력 표현과 연산을 지원한다. 특히 시간지원 집계는 현재시점에서 유효한 자료뿐만 아니라 이력 자료로부터 일련의 계산을 통해 부가적인 정보를 생성해내는 기능을 갖는다. 따라서 다양한 유형의 집계함수의 지원은 전반적인 데이터베이스 시스템의 편리함과 성능을 결정하는 중요한 요소가 된다. 이 논문에서는 시간지원 집계 질의에 대한 효율적인 처리 방안으로서 시간지원 집계 트리 전략을 소개하고, 그 처리 비용을 분석하고 성능을 평가한다.