• International Journal of Ocean System Engineering
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• v.3 no.4
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• pp.164-168
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• 2013

Tidal-current power is now recognized as a clean power resource. The turbine blade is the fundamental component of a tidal current power turbine. The kinetic energy available within a tidal current can be converted into rotational power by turbine blades. While in service, turbine blades are generally subjected to cyclic fatigue loading due to their rotation and the rotor-tower interaction. Predicting the fatigue life under a hydrodynamic fatigue load is very important to prevent blade failure while in service. To predict the fatigue life, hydrodynamic load data should be acquired. In this study, the vibration characteristics were analyzed based on three-dimensional unsteady simulations to obtain the cyclic fatigue load. Our results can be applied to the fatigue design of horizontal-axis tidal turbines.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.10
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• pp.164-168
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• 2003

An automotive wheel bearing is one of the most important components to guarantee the service life of a passenger car. The endurance life of a bearing is affected by many parameters such as material properties, heat treatment, lubrication conditions, operating temperature, loading conditions, bearing geometry, the internal clearance of bearing and so on. In this paper, we analyze the relation between loads and deformations of wheel bearing units for optimal bearing unit design. On the basis of it, we calculate the endurance life of w heel bearing units and analyze the contribution of bearing geometric parameters on the endurance life by using Taguchi method.

• Wind and Structures
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• v.32 no.5
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• pp.501-508
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• 2021

The turbine industry demands a reliable design with affordable cost. As technological advances begin to support turbines of huge sizes, and the increasing importance of wind turbines from day to day make design safety conditions more important. Wind turbines are exposed to environmental conditions that can affect their installation, durability, and operation. International Electrotechnical Commission (IEC) 61400-1 design load cases consist of analyses involving wind turbine operating conditions. This design load cases (DLC) is important for determining fatigue loads (i.e., forces and moments) that occur as a result of expected conditions throughout the life of the machine. With the help of FAST (Fatigue, Aerodynamics, Structures, and Turbulence), an open source software, the NREL 5MW land base wind turbine model was used. IEC 61400-1 wind turbine design standard procedures assessed turbine behavior and fatigue damage to the tower base of dynamic loads in different design conditions. Real characteristic wind speed distribution and multi-directional effect specific to the site were taken into consideration. The effect of these conditions on the economic service life of the turbine has been studied.

• Computational Structural Engineering
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• v.23 no.5
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• pp.23-33
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• 2010

• Journal of the Korean housing association
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• v.12 no.2
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• pp.181-190
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• 2001

The purpose of this study is to analysis web sites which relate to housing environment on Internet and to suggest guidelines which are needed in digital life. Data are in 53 web sites searched by housing environmental word such as people, living, town and so on. The web sites are analyzed by key words. The results of this study were as follow: The web sites are divided into e-housing community, e-housing management, e-housing workplace and e-housing design. These are the digital life of new type. E-housing community sitess key words are 3D virtual world, chatting, information, service, community etc. E-housing community is related to making new wired community cross time and space. E-housing management sitess key words are guard management, apartment management, building management etc. E-housing management sites provide the useful information of housing management. E-housing workplace sitess key words are virtual office. conference etc. E-housing workplace sites enable us to work in cyberspace. E-housing design sitess key words are design, interior, furniture etc. E-housing design sites provide marketing, consulting and designing in relation to the house. The web life style on cyberspace is common and makes many changes happen in house life and environment.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.6
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• pp.1197-1202
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• 2017

Security services that support electric energy service gateway require relatively high reliability. In particular, the application services that accompany communications and data are run organically. Each of the security services should support a secure service platform that supports a secure, scalable life cycle for existing services which should be extends security layer of Universal Middleware. In this convergence platform, it is the study of security transfer modular services that allow independent life cycle management of systems through Universal middleware. First, It is modular in terms of energy consumption service and data, enabling real-time operation, communications, remote management and applications. Second, the life cycle of the secure module to support start, stop and updating of the security module by applying the security policy module layer concept. It is modular system enabling to design of dyanmic models in the smart grid, the service was intended to be standardized and applied to the security service platform.

• Journal of the Ergonomics Society of Korea
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• v.31 no.1
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• pp.63-76
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• 2012

Objective: The main objective of this study is to propose a user-centered assessment metric for ubiquitous services. Background: As the ubiquitous era took off, the interactions between ubiquitous services and users have come to take an important position. It is essential to conceptualize a new assessment model that considers human-system interaction capability with a user-centered design perspective. Method: The evaluation model for the interactivity of ubiquitous service was approached from the concept of usability and inter-personality of services. As a validation study, suggested assessment metric was utilized to evaluate the u-Home service. Priority weighting of each assessment metric was derived using the quantification type-I analysis. Results: To evaluate interactivity, this study suggested a quantitative metric for user testing performed after classifying the interactivity characteristics to contextualization; ubiquity; user experience; and service capability. Conclusion: This study suggest the metric for the ubiquitous service that are experienced in real life, and introduced the concept of ubiquitous service interactivity. Application: The suggested evaluation metric can be used to evaluate interactivity level of ubiquitous service and identify the potential problem and usability requirements at the early stage of service development.

• Journal of Digital Convergence
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• v.15 no.3
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• pp.301-306
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• 2017

With the popularization of smart-phone, a variety of application service user is a rising trend now. In contrast, studies concerning library application service that cast a long shadow over the life of students and citizens still lacking in many ways. This study evaluates user experience of Young-in Si public library application service, and investigates user requirements. I searched the real user reviews about Young-in Si library application both App store and Android market. As the final outcome, I found inconveniences and improvements of this service. The application is intuitive, but requires consistent design, strong identity and customizing main page. It will be suggested specific guidelines for the public library mobile services in other areas.

• International Journal of Highway Engineering
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• v.15 no.2
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• pp.47-55
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• 2013

PURPOSES : This study aimed to evaluate the feasibility of AASHTO86 design method for Bonded Concrete Overlay. METHODS : The Feasibility of AASHTO86 design method for Bonded Concrete Overlay is investigated based on the following study : i) Sensitivity analysis of designed service life of Bonded Concrete Overlay by major design input for AASHTO86 guide. ii) Comparison of actual Bonded Concrete Overlay life and predicted Bonded Concrete Overlay life by AASHTO86. iii) Finding the stress component influence the potential distress of Bonded Concrete Overlay based on 3-d FEM analysis. iv) Exploring the limitation of AASHTO86 in the aspect of design input. RESULTS : Sensitivity analysis showed that the condition of existing pavement significantly on the Bonded Concrete Overlay life. Also the overlay thickness affect the Bonded Concrete Overlay life. The comparison of actual Bonded Concrete Overlay life and predicted Bonded Concrete Overlay life showed relatively good agreement when the early distress sections are excluded in comparison. Bonding stress occurred at the interface may be larger than the bond strength used in the specification of Bonded Concrete Overlay construction. CONCLUSIONS : Bonded Concrete Overlay life predicted by the AASHTO86 may not be reliable. Number of points to improve the reliability in the design of Bonded Concrete Overlay are suggested in this study.

• Korean Institute of Interior Design Journal
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• v.22 no.5
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• pp.3-10
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• 2013

The principle of aging-in-place should be fundamental in designing post-retirement homes to support baby boomers' healthy aging in their current living conditions. This study investigated Korean-American baby boomers' opinions about their life images in their post-retirement homes and the needs for supportive services therein. A questionnaire survey was conducted, and a total of 247 responses were used for statistical analyses. As the most important life image for their post-retirement homes, baby boomers emphasized the living environments offering various recreational activities. They indicated the post-retirement homes close to their children or family members as the next important life image. These opinions differed depending on their socioeconomic characteristics. In particular, baby boomers with higher-income preferred housing environments offering diverse recreational activities while those with lower-income preferred the housing close to more employment opportunities. In terms of supportive services available in the post-retirement homes, they wanted 'healthcare assistance services' and 'diverse recreational programs.' Gender, educational attainment, and annual income affected their preferences in these services, though. Based on the findings, this study concluded that post-retirement housing environments should create spaces to accommodate various recreational activities and include places for them to work in near-home environments. In the community, various need-based customized recreational activities and educational programs should be planned considering different socioeconomic characteristics of baby boomers. All these considerations will provide supportive residential environments for their successful aging in place.