• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.2
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• pp.163-170
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• 2008

The aeroelastic stability analysis of a soft-in-plane, composite hingeless rotor blade in hover and in forward flight has been performed by combining the mixed beam method and the aeroelastic analysis system that is based on a moderate deflection beam approach. The aerodynamic forces and moments acting on the blade are obtained using the Leishman-Beddoes unsteady aerodynamic model. Hamilton's principle is used to derive the governing equations of composite helicopter blades undergoing extension, lag and flap bending, and torsion deflections. The influence of key structural modeling issues on the aeroelastic stability behavior of helicopter blades is studied. The issues include the shell wall thickness, elastic couplings and the correct treatment of constitutive assumptions in the section wall of the blade. It is found that the structural modeling effects are largely dependent on the layup geometries adopted in the section of the blade and these affect on the stability behavior in a large scale.

• Journal of People, Plants, and Environment
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• v.22 no.5
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• pp.525-539
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• 2019

Much research has been conducted on user behavior by taking surveys and interviews to plan the green space effectively. However, there is a limitation in understanding detailed user characteristics such as personalities and values. This study applied the Persona-based Scenario Method (PSM) to Hongneung Experimental Forest to understand the detailed needs and behaviors of the users in the forest recreation area. The PSM is a user experience modeling technique, which tries to understand the users by describing the type of users as real people. This study 1) extracts the factors of visitor recreation activities in Hongneung Experimental Forest based on the results of the survey, 2) develops user personas based on the results of survey and comes up with activity factors, and 3) designs user scenarios. As a result of applying the PSM, 64 factors of visitor activities were derived from the observation survey in 14 sites of Hongneung Experimental Forest and 25 key factors of visitor activities were chosen through observer's brainstorming. Second, three types of personas were developed considering the key factors and the results of user characteristics with quantitative and qualitative analysis. Lastly, context scenarios were designed by applying the key factors of visitor recreation activities to the persona model. We identified the design problems of the space and design requirements through the scenarios. This study has significance in that it takes an approach from the user perspective and was applied to the forest recreation area, which was mainly used in product design. The developed personas could be used for deriving design elements and setting the direction for planning considering detailed needs, behaviors and characteristics of users.

• Architectural research
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• v.17 no.1
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• pp.13-20
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• 2015

The physical environment can dramatically affect students' feeling and their behavior, educational attainment, and the way in which we do school activities. Unlimited access to campus areas without appropriate securities have reported an increase of crime in school area and safety issues has encouraged school facility planners to install securities devices at every corner of buildings. However, it is still questionable whether this approach is enough to protect students and staffs from the victimization of crime, including thefts, burglaries and sexual offences. There has been continued doubt about the safety of educational facilities where individual college students are studying and enjoying extra-curricular activities. Therefore, the purpose of this study is intended to investigate the effects of perception of safety by students on the level of academic performance at public outdoor environment of university campus. An extensive literature noted that the central element of modern school design principle mainly holds the theory of crime prevention through environmental design (CPTED) and the concept of defensible space. The second generation of CPTED also focused on social soft issues as well as situational factors, which extends beyond mere physical design to include social factors. The correlation analysis found that the effect of sense of safety does appear to be statistically significant on the facilitation of academic achievement. However, the analysis of Chi-square concluded that the perception of safety was not related to demographic and socio-economic profiles of the group except for gender. Further, stepwise multiple regression analysis revealed that the most prime predictor for academic achievement were 'safe public outdoor space/paths' at university campus environment, implying careful design of public open space and sidewalks based on the guideline of CPTED. The study also demonstrated that as the level of positive perception of safety rose, the overall academic achievement also responded to the specified rate (${\beta}=.99$). Finally, the findings reinforce an evidence that high-quality school environments are a positive factor in student academic performance.

• Journal of the Korean Institute of Landscape Architecture
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• v.21 no.3
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• pp.11-19
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• 1993

This study was intended to clarify the landscape characteristics of the Sosewon Gaden through interpreting the Kim, In Hu's 48 poems(in Chinese characters) which clearly represented the landscape image of th user about this garden by selecting the cultural position of how then the users of the garden interpreted and manipulated its landscape rather than the scientific position. The following were the results from the analysis and review of the review of the woodcut and the 48 poems through names and scenic element. 1. When analyzing the names, those names due to the human experience were the most. This revealed that sensitive perception and experience was emphasized in the garden life. 2. It was important that can be experienced as nature and human beings come in contact each other at stream. 3. The landscape of the Sosewon Garden empasized not only the elements of the form and their combination but also on the unusual experience of human behavior and climatic element. The elements of the form which was recognized as the subject of poet was regarded as the cultural one of this garden and had an ideological background to convey the meaning of the landscape. 4. The Sosewon Garden was divided into four characteristic spaces as it is considered in terms of the sense of place represented in the 48 poems; the approach space, the space for poetic recital, the ideal space, and the space of pleasure.

• Journal of Mechanical Science and Technology
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• v.17 no.3
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• pp.321-328
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• 2003

The elongation of contact length on the line of action is considered with particular reference for roll forming of gears, and for dynamic behavior of the tooth in meshing. However there is no paper that discuss the elongation of contact length in the load meshing of gears. Based on our investigation, the contact length on the line of action elongates more than the kinematically calculated value. In rolling, as the tool approaches the workpiece, the center distance of the gears decreases by a small amount. But, the elongation of contact length is sensitive. Therefore, the contact point on the line of action is difficult to be determined, which complicates the tooth analysis. In this study, the exact relation between the elongation of contact length and the tooth space over the recess or before the approach are revealed by experiments and kinematic theory. This analytical result applies not only for rolling, but also for the single flank meshing which is done under constant center distance.

• 한국경영정보학회:학술대회논문집
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• 2008.06a
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• pp.52-63
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• 2008

Virtuality is a product of the information age, and as it plays a larger role in the activities of individuals, groups and organizations, the issue of how human behavior varies between virtual and physical space has become one of the most important questions facing the management environment of today. The purpose of this article is to examine how virtuality shapes individuals' social relationships within and outside their work groups. We developed a conceptual framework that explores the links between virtuality and social network based on computer-mediated communication theory and social network theory. Using data from 172 individuals of 42 project teams in 5 global business consulting firms, we tested cross-level hypotheses. The results of hierarchical linear modeling (HLM) indicate that virtuality significantly influences individual's internal tie strength as well as external bridging ties. The results also show the effects of virtual process via CMC vary along with the virtual context.

• Korean Institute of Interior Design Journal
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• no.3
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• pp.18-25
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• 1994

Interior design is an inerdisciplinary field that is in the early stages of theory development, it is necessary to build theoretical frame work for the research. The purpose of this study is to present interior design and guidelines in a three generation family apartment for the elderly, and to develop a theoretical framework on the basis of the human ecosystem approach for analysis of relations between elderly and environment. Analysis and investigations are done by literature review about residential environmental characteristics of the elderly based on the findings of the conceptual analysis. Environmenta elements of interor design related to elderly in a three generation family apartment are as follow ; First, Natural environmental element is orientation, site, temperature, local weather. Second, human behavioral element is privacy , interior design requirement based on physical and psychological effect, housing policy, behavior. Third, Human constructed environmental element is size of apartment space, interior design component, human dimension, aesthetic condition.

• Structural Engineering and Mechanics
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• v.35 no.2
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• pp.217-240
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• 2010

A semi-analytical method is presented for accurately prediction of the free vibration behavior of generally laminated composite plates with arbitrary boundary conditions. The method employs the technique of separation of spatial variables within Hamilton's principle to obtain the equations of motion, including two systems of coupled ordinary homogeneous differential equations. Subsequently, by applying the laminate constitutive relations into the resulting equations two sets of coupled ordinary differential equations with constant coefficients, in terms of displacements, are achieved. The obtained differential equations are solved for the natural frequencies and corresponding mode shapes, with the use of the exact state-space approach. The formulation is exploited in the framework of the first-order shear deformation theory to incorporate the effects of transverse shear deformation and rotary inertia. The efficiency and accuracy of the present method are demonstrated by obtaining solutions to a wide range of problems and comparing them with finite element analysis and previously published results.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.51 no.3
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• pp.111-119
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• 2002

This paper proposes a speed control system based on a fuzzy logic approach, integrated with a simple and effective adaptive algorithms. And this paper attempts to provide a thorough comparative insight into the behavior of induction motor drive with PI, direct and improved fuzzy speed controller. A indirect vector controlled induction motor is simulated under varying operating condition. The validity of the comparative results is confirmed by simulation results for induction motor drive system.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.2
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• pp.69-78
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• 1995

Nonlinear analysis methods are developed which will enable the reliable prediction of the dynamic behavior of the space shuttle main engine(SSME) turbopumps in the presence of bearing clearances and other local nonlinearities. A computationally efficient convolution method, based on discretized Duhamel and transition matrix integral formulations, is developed for the transient analysis. In the formulation, the coupling forces due to the onlinearities are treated as external forces acting on the coupled subsystems. Iteration is utilized to determine their magnitudes at each time increament. The method is applied to a nonlinear generic model of the high pressure oxygen turthods, the convolution approach proved to be more accurate and highly more efficient. For determining the nonlinear, steady-state periodic responses, an incremental harmonic balance(IHB) method was also developed. The method was successfully used to determine dominantly harmonic and subharmonic(subsynchronous) responses of the HPOTP generic model with bearing clearances. A reduction method similar to the impedance formulation utilized with linear systems is used to reduce the housing-totor models to their coordinates at the bearing clearances.