• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1998년도 제13차 학술회의논문집
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• pp.519-524
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• 1998

This paper presents a robust control scheme of free-joint manipulators to overcome actuator failures and uncertain-ties in Cartesian space where tasks are planned. The control scheme has the adaptation law for the upper bound on the norm of uncertainties through the Lyapunov function approach. To solve the dynamic singularity problem in the controller, the singular and nonsingular regions are investigated based on a computer simulation. Then a singularity-free Cartesian trajectory planning is achieved in order to guarantee the availability of the control scheme. To illustrate the validity of the proposed control scheme, simulation results for a three-link planar robot arm with a free joint are shown.

• 가정과삶의질연구
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• 제16권1호
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• pp.27-38
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• 1998

The purpose of this study was to identify the level of residential privacy perceived by the elderly and also to identify contributing factors on their perception of privacy. This study examined the relations among socio-demographic characteristics housing characteristics and personal perception of privacy. The number of 469 elderly aged 55 and over were interviewed in Seoul. Daejeon Jeonju and Daegu, The data were analyzed by statistical methods such as frequencies means and multiple liner regression analysis. The result showed that the significant variables related to the perception of residential privacy of the elderly were the personal self-esteem age housing tenure pattern of using spaces family solidarity and availability of the perception of private space. The perception of the privacy of the elderly can be affected by personal characteristics and the privacy can be achieved by improving their present housing environment.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2001년도 추계학술발표논문집 (상)
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• pp.363-366
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• 2001

It is very difficult to maintain the performance of estimation models for the new breed of projects since the computing environment changes so rapidly in terms of programming languages, development tools, and methodologies. So, we propose to use the relevant cases for a neural network model, whose cost is the decreased number of cases. To balance the relevance and data availability, the qualitative input factors are used as criteria of data classification. With the data sets that have the same value for certain qualitative input factors, we can eliminate the factors from the model making reduced neural network models. So we need to seek the optimally reduced neural network model among them. To find the optimally case-selective neural network, we propose the search techniques and sensitivity analysis between data points and search space.

• Journal of Electrical Engineering and Technology
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• 제7권2호
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• pp.193-199
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• 2012

Worldwide cardiovascular diseases are the major cause of death. Aside from heart transplants, which are limited due to the availability of human donor hearts, artificial hearts are the only therapy available for terminal heart diseases. For various reasons, a total implantable artificial heart is desirable. But the limited space in the human thorax sets rigorous restrictions on the weight and dimensions of the device. Nevertheless, the appropriate functionality of the artificial heart must be ensured and blood damage must be prevented. These requirements set further restrictions to the drive of this device. In the this paper, two optimization methods, namely, the manual parameter variation and Differential Evolution algorithm, are presented and applied to match the specifications of an artificial heart.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권11호
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• pp.5323-5343
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• 2018

Mobile applications and social networks tend to enhance the need for high-quality content access. To address the rapid growing demand for data services in mobile networks, it is necessary to develop efficient content caching and distribution techniques, aiming at significantly reduction of redundant content transmission and thus improve content delivery efficiency. In this article, we develop optimal cooperative content cache and distribution policy, where a geographical cluster model is designed for content retrieval across the collaborative small cell base stations (SBSs) and replacement of cache framework. Furthermore, we divide the SBS storage space into two equal parts: the first is local, the other is global content cache. We propose an algorithm to minimize the content caching delay, transmission cost and backhaul bottleneck at the edge of networks. Simulation results indicates that the proposed neighbor SBSs cooperative caching scheme brings a substantial improvement regarding content availability and cache storage capacity at the edge of networks in comparison with the current conventional cache placement approaches.

• International Journal of Advanced Culture Technology
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• 제9권1호
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• pp.22-27
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• 2021

Morphology of contemporary city streets is composed of overlapping infrastructures corresponding to the new street within the established organization, contemporary system, future circumstance, and population. As well, two overlaid organizations and morphological, historical, social and physical development lead to sharp acute algle(triangular) site, and the architecture in this site has a restriction on the availability of the internal space and the external design due to outside shape sharpness. We want to have a positive effect on the internal and external design of the architecture in the future by categorization of the shape and processing characteristics of the acute angle corner of the trilateral site. The characteristics and design categorization shown in this case study are as follows. Constitution a unique and independent form, lead streets and shape a exclusive image of the landscape, alleviate sharpness by configuring a acute angle point as a plane, use void to give reserve character, replace roundness for companionability to induce ambience in the road, embrace the characteristics of the site and create internal spaces and functions, emphasize the characteristics of each stairs, retain of uniqueness and highlight the characteristics of a vertical elements.

• ETRI Journal
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• 제44권6호
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• pp.966-976
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• 2022

Optical wireless communication, or free space optics, is a promising solution for backhauls in sixth-generation mobile systems. However, the susceptibility of optical links to weather conditions has led to FSO links being furnished with radio frequency (RF) backups. These Hybrid FSO/RF systems provide enhanced link availability but lead to RF resource wastage. Cognitive radio technology, in contrast, is well known for its optimal use of RF resources and may be combined with an FSO link to create a Cognitive Hybrid FSO/RF system. This work uses such a system to analyze a configuration for a mobile backhaul in sixth-generation mobile systems. This configuration can seamlessly coexist with established large scale RF cellular networks. The performance of this configuration is analyzed with respect to outage probability and average bit error by considering the impact of optical channel turbulence, misalignment loss, RF interference, and noise. Mathematical closed-form expressions are verified by simulations.

• 한국조리학회지
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• 제11권2호
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• pp.67-90
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• 2005

In this study, to improve the quality of school lunch in local colleges, we conducted a survey on students who attend 2 year colleges in Jeju region. With its own unique regional characteristics and the change of its school lunch program from direct management to consignment, there were some questions about how each factor in school lunch program affects on students' satisfaction with it and we tried to present helpful data to improve school lunch programs in each region. The survey took place from May 5 to May 10, 2005 covering the colleges only in Jeju region. There were 200 sets of questionnaires issued and distributed to the students who are currently using school lunch programs. Only 168 sets were retrieved and processed statistically. 2 sets out of 168 questionnaires had to be thrown away because there were wrong entries of some questions, which made overall retrieving rate 83%. In this study, SPSS 10.0 , one of the statistical package programs, was used as an analyzing tool to make Frequency Analysis. To verify credibility, Cronbach's Alpha Element Analysis was done and T-test and ANOVA was also made. After Recurrence Analysis for elements of satisfaction regarding main factors that is considered to be important to customers, we found that importance of following factors: appearance of food, incongruity between main and side dishes, availability of seasonal food, availability of preferred menu, absence of food stock, waiting time, accessibility of food counters, space between chairs, presentation of a menu, food tray's shape, and color of food trays. The importance of those showed high but satisfaction with the same factors was low. So the primary improvement on these factors should be made to increase satisfaction. Finally we concluded that in large extent, importance of each factor definitely affects on students' satisfaction.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제4권4호
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• pp.491-508
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• 2010

In peer-to-peer (P2P) on-demand streaming networks, the alleviation of server load depends on reciprocal stream sharing among peers. In general, on-demand video services enable clients to watch videos from beginning to end. As long as clients are able to buffer the initial part of the video they are watching, on-demand service can provide access to the video to the next clients who request to watch it. Therefore, the key challenge is how to keep the initial part of a video in a peer's buffer for as long as possible, and thus maximize the availability of a video for stream relay. In addition, to address the issues of delivering data on lossy network and providing scalable quality of services for clients, the adoption of multiple description coding (MDC) has been proven as a feasible resolution by much research work. In this paper, we propose a novel caching scheme for P2P on-demand streaming, called Dynamic Buffering. The proposed Dynamic Buffering relies on the feature of MDC to gradually reduce the number of cached descriptions held in a client's buffers, once the buffer is full. Preserving as many initial parts of descriptions in the buffer as possible, instead of losing them all at one time, effectively extends peers’ service time. In addition, this study proposes a description distribution balancing scheme to further improve the use of resources. Simulation experiments show that Dynamic Buffering can make efficient use of cache space, reduce server bandwidth consumption, and increase the number of peers being served.

• 한국식생활문화학회지
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• 제13권5호
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• pp.423-430
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• 1998

The purposes of this study were to (a) measuring attitude and satisfaction of Yonsei university students towards contracted vs. rented university foodservices, (b) determine university students' overall satisfaction & perception regarding the factors improved towards university foodservice and (c) provide recommendation on marketing strategies for university foodservices. Questionnaires were hand delivered to 600 Yonsei University students by designated coordinators. A total of 549 questionnaires were usable; resulting in an 93% response rate. The survey was conducted between October 12 to October 18, 1995. Statistical data analysis was completed using the SAS Programs for descriptive analysis, T-test, ${\chi}^2-test$, ANOVA, Factor Analysis and Stepwise Multiple Regression. The results of this study can be summarized as follows: 1. Performance mean score for contracted foodservice management in terms of food, menu, price, hygiene, facilities was higher than for rented foodservice management. 2. The average satisfaction score for contracted foodservice management in terms of price was lower than for rented foodservice management. There was no gap between contracted foodservice management and rented foodservice management in overall satisfaction score and price satisfaction score. 3. Perception regarding the factors improved of thirteen factors to be improved except operating hours, waiting time, price, food quantity were perceived as better by students. 4. Perception regarding the factors improved have correlation with foodservice qualify attribute's performance. 5. According to multiple regression analysis, 92.05% of the variance in respondents' satisfaction score could be explained by procedure after meal, purchasing procedure, operating hours, availability of breakfast, waiting time, atmosphere, price, facilities, service endeavor to survey satisfaction in foodservice, availability of kitchen and wall space, portion size, taste of food, change of cafeteria name, the number of seats, and variety of menu.