• 한국조경학회지
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• 제27권4호
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• pp.80-86
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• 1999

The purpose of this study was to suggest a case study and anlaysis of the visual impact in dam construction through visual impact assessment method in Dong-sang river. The results can be summarized as follows; 1) For the evaluation of the visual impact of dam construction, five steps such as field analysis of visual status, finding visual sensitivity area and visual control point, making visual simulation material and evaluation, and visual impact analysis and assessment were suggested as desirable. 2) In the case study, the visual impact of dam construction was evaluated to be simple, unique, modern, static, cool and unfamiliar. 3) There was a few difference between the pre-construction and post-construction in statistical test. Especially, The dam in Man-Jee area was evaluated to be artificial, unique and destroyed in statistical difference, and then we design dam structure with visual friendliness. 4) In conclusion, there was high correlation between pre-construction landscape and post-construction landscape through semantic differential scale method using eleven adjectives. Therefore, we state that there is no visual impact for the dam construction for the moment.

• Structural Engineering and Mechanics
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• 제91권2호
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• pp.197-209
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• 2024

The vibration of elastically supported bidirectional functionally graded (BDFG) sandwich beams on an elastic foundation is investigated. The sandwich structure is composed of upper and lower layers of BDFG material and the core layer of isotropic material. Material properties of upper and lower layers are assumed to vary continuously along the length and thickness of the beam with a power-law function. Hamilton's principle is used to deduce the vibration equations of motion of the sandwich Timoshenko beam. Then, the partial differential equation of motion is spatially discretized into a time-varying ordinary differential equation in terms of Chebyshev differential matrices. The eigenvalue equation associated with the free vibration is formulated to study the influence of various slenderness ratios, material gradient indexes, thickness ratios, foundation and support spring constants on the vibration frequency of BDFG sandwich beams. The present method can provide researchers with deep insight into the impact of various geometric, material, foundation and support parameters on the vibration behavior of BDFG sandwich beam structures.

• 대한수학교육학회지:수학교육학연구
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• 제14권3호
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• pp.221-237
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• 2004

본 연구는 개념적 은유의 분석을 통해 RME 기반 대학 미분방정식 수업에 참여한 학생들의 개념적 모델의 변환을 탐구하였다. 분석 결과 학기초 이산적이고 양적인 개념적 모델이 학생들의 수학적 토의 맥락에서 지배적이었으나 맥락문제탐구에 기반한 수학적 의미의 재조정 과정을 통해 연속적이고 질적인 사고를 반영하는 개념적 모델이 발생하여 기존의 개념적 모델이 확장됨이 밝혀졌다. 이와 같은 개념적 모델의 변환은 본 프로젝트 교실 참여가 학생들의 미분방정식에 대한 문제해결적 사고의 유연성을 증대시키는데 기여하였음을 보여준다. 이와 같은 분석 결과에 기초하여, 본 논문은 학생들의 개념적 모델의 변환을 촉발한 교수학적 요소에 대한 논의를 통해 학생들의 개념적 모델 변환이 가지는 사회문화적 의미를 조명하고 RME 기반 수학 수업 모델의 학교 현장 적용에 유용한 시사점을 제공하였다.

• 한국통신학회논문지
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• 제35권1A호
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• pp.1-9
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• 2010

본 논문을 통해 i.n.d 레일리 패이딩 체널에서 서로 다른 변조/복조 기법을 사용하는 중계기들로 구성된 선택적 복호 후 재전송 네트워크의 성능평가를 보여준다. 본 논문은 i.i.d와 i.n.d 레일리 패이딩 채널 모두에서 선택적 복호 후 전송 프로토콜이 최대 다이버시티를 얻을 수 있다는 것을 보여준다. 또한 SC(selection combining)기법을 사용하는 시스템과 MRC(maximal ratio combining)기법을 사용하는 시스템의 성능을 비교하여 결합기술의 효과를 연구하였다. 높은 SNR에서 시뮬레이션 결과와 수식적 분석 결과가 정확하게 일치하는 것을 보여준다.

• 한국수학교육학회지시리즈A:수학교육
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• 제42권3호
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• pp.387-402
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• 2003

Realistic Mathematics Education (RME) focuses on guided reinvention through which students explore experientially realistic context problems to develop informal problem solving strategies and solutions. This research applied this philosophy of RME to design a differential equation course at a university level. In particular, the course encouraged the students of the course to use numerical methods to solve differential equations. In this context, the purpose of this research was to describe the developmental process in which the students constructed and reinvented Euler algorithm in the class. For the purpose, this paper will present the didactical principle of RME and describe the process of developmental research to investigate the inferential process of students in solving the first order differential equation numerically. Finally, the qualitative analysis of the students' reasoning and use of symbols reveals how the students reinvent Euler algorithm under the didactical principle of guided reinvention. In this research, it has been found that the students developed deep understanding of Euler algorithm in the class. Moreover, it has been shown that the experience of doing mathematics in the course had a positive impact on students' mathematical belief and attitude. These findings imply that the didactical principle of RME can be applied to design university mathematical courses and in general, provide a perspective on how to reform mathematics curriculum at a university level.

• 대한기계학회논문집A
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• 제20권5호
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• pp.1486-1497
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• 1996

The problem of determining the 3-demensional motion of any two rough bodies after a collision involves some rather long analysis and yet in some points it differs essentially from the corresponding problem in tdwo dimensions. We consider a special problem where two rough ellipsolids moving in any manner collide, and analyze the three dimensional impact process with Coulomb friction and Poisson's hypothesis. The differential equations that describe that process of the impact induce a flow in the tangent velocity space, the flow patterns characterize the possible impact cases. By using the graphic method in impulse space and numerical integration thchnique, we analyzed the impact process inall the possible cases and presented the algorithm for determining the post-impact motion. The principles could be applied to the general problem in three dimensions. We verified the effectiveness of the analysis results by simulating the numerous significant examples.

• Smart Structures and Systems
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• 제24권1호
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• pp.95-110
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• 2019

The semi-active impact damper (SAID) is proposed to improve the damping efficiency of traditional passive impact dampers. In order to investigate its damping mechanism and vibration control effects on realistic engineering structures, a 20-story nonlinear benchmark building is used as the main structure. The studies on system parameters, including the mass ratio, damping ratio, rigid coefficient, and the intensity of excitation are carried out, and their effects both on linear and nonlinear indexes are evaluated. The damping mechanism is herein further investigated and some suggestions for the design in high-rise buildings are also proposed. To validate the superiority of SAID, an optimal passive particle impact damper ($PID_{opt}$) is also investigated as a control group, in which the parameters of the SAID remain the same, and the optimal parameters of the $PID_{opt}$ are designed by differential evolution algorithm based on a reduced-order model. The numerical simulation shows that the SAID has better control effects than that of the optimized passive particle impact damper, not only for linear indexes (e.g., root mean square response), but also for nonlinear indexes (e.g., component energy consumption and hinge joint curvature).

• Asia pacific journal of information systems
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• 제27권4호
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• pp.191-215
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• 2017

This study investigated the antecedents and the performance impact of two types of Smartphone functions (communication vs. computing functions) in organizational environment and the moderating impact of Smartphone users' organizational roles. More specifically, identifying two distinct types of Smartphone functions such as communication functions and computing functions (including informational, social network, and resource management functions), we investigated the impact of three antecedents (Smartphone dependency, task mobility, and perceived critical mass) on the use of the two Smartphone functions and how organizational workers' perceived performance gains differ by using these two different Smartphone functions for their workplace activities. We tested our hypotheses with survey data collected from 176 organizational workers. Our findings suggest that Smartphone dependency, task mobility and perceived critical mass of Smartphone use are significantly associated with the use of the two different functions, and that the use of computing functions is more strongly associated with perceived performance gain than the use of communication functions. We also found that managerial roles played by individual workers differently moderate the impact of Smartphone use on perceived performance gain. The present findings enable researchers and practitioners to better understand the impact of Smartphone use in workplaces.

• Journal of Preventive Medicine and Public Health
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• 제42권3호
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• pp.199-207
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• 2009

Objectives : Research on the gender differences of health among older Korean people has been limited compared with the research for other stages of life. This study first examined the patterns and magnitude of the gender differences of health in later life. Second, we examined the gender differences in the health of older men and women that were attributable to differing socioeconomic conditions. Methods : Using the nationally representative 2005 Korean National Health and Nutrition Examination Survey, the gender differences in disability and subjective poor health were assessed by calculating the age adjusted and gender-specific prevalence. Logistic regression analyses were used to assess if the differences between the men and women for health could be explained by differential exposure to socioeconomic factors and/or the differential vulnerability of men and women to these socioeconomic factors. Results : Our results indicated that older women were more likely than the men to report disability and poor subjective health. The health disadvantage of older women was diminished by differential experiences with socioeconomic factors, and especially education. The differences shrink as much as 43.7% in the case of disability and 35.4% in the case of poor subjective health by the differential exposure to educational attainment. Any differential vulnerability to socioeconomic factors was not found between the men and women, which means that socioeconomic factors may have similar effect on health in both genders. Conclusions : Differential socioeconomic experience and exposure between the men and women might cause gender difference in health in old age Koreans.

• 한국경제지리학회지
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• 제26권1호
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• pp.55-71
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• 2023

본 논문은 도시성장, 신 도시개발, 개발업자, 도시계획가, 주택, 부동산 시장, 커뮤니티 계획, 커뮤니티 자금 조달, 지방 정부, 토지 이용 계획, 공공시설, 개발 비용에 초점을 맞추어 개발부담금 산정에 대해 이론적으로 고찰하였다. 개발부담금을 누가 부담해야 하는지에 대한 많은 질문이 실증적 분석을 기반으로 한 답변을 요구한다. 이러한 질문에는 토지 소유자가 부담하는 정도, 다양한 수준의 개발부담금이 커뮤니티의 사회경제적 혼합에 미치는 영향, 지역 내 재정 혜택의 분배 등이 포함된다. 더 광범위한 질문은 개발부담금의 차별적 부과가 도시 및 지역 형태에 어떻게 영향을 미치는가 그리고 개발부담금이 지역 성장을 보다 효율적으로 또는 덜 효율적으로 만드는가에 관한 것이다. 누가 개발부담금을 궁극적으로 지불하는가? 시장이 개발부담금에 어떻게 반응하는지에 대한 실증적 평가는 매우 부족하지만, 전반적으로 거주자(주민과 사용자)가 개발부담금의 대부분을 지불하는 것으로 알려져 있다.