• Proceedings of the Korea Database Society Conference
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• 2008.05a
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• pp.183-192
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• 2008

This paper is to provide the guideline of U-commerce Adoption In the Ubiquitous environment. Personalization is the Key in U-commerce. The guideline helps the understand difference personalization in U-commerce with M-commerce or E-commerce. we described U-commerce's prospective applications and personalization characteristics. So, according to TAM, we described what the perceived values of adoption and how perceived values of adoption can effect to adoption intention.

• 한국방재학회:학술대회논문집
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• 2008.02a
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• pp.127-130
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• 2008

This study demonstrates a basic concept and designing direction for the realisation of disaster prevention planning in u-City(u-BangjaeCity) that is from establishing a planning system in terms of the areas of professional disaster and safety management for the national disaster management. and designing disaster or safety management system via using ubiquitous technology for the scientific disaster management. In order to realise u-City it is necessary to maps out interrelation amongst various services such as traffic, environment and disaster prevention. Domestic and international case studies regarding the tendency of disaster prevention planing in u-City and its analysis could be the fundamental resource in order to develop the standard model of u-BangjaeCity.

• Journal of the Korean Mathematical Society
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• v.47 no.4
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• pp.819-830
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• 2010

We prove, in this article, that a ring R is a stable exchange ring if and only if so are all its Pierce stalks. If every Pierce stalks of R is artinian, then $1_R$ = u + $\upsilon$ with u, $\upsilon$ $\in$ U(R) if and only if for any a $\in$ R, there exist u, $\upsilon$ $\in$ U(R) such that a = u + $\upsilon$. Furthermore, there exists u $\in$ U(R) such that $1_R\;{\pm}\;u\;\in\;U(R)$ if and only if for any a $\in$ R, there exists u $\in$ U(R) such that $a\;{\pm}\;u\;\in\;U(R)$. We will give analogues to normal exchange rings. The root properties of such exchange rings are also obtained.

• Bulletin of the Korean Mathematical Society
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• v.51 no.1
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• pp.189-206
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• 2014

In this paper, we prove the global existence and uniqueness of the dissipative Kirchhoff equation $$u_{tt}-M({\parallel}{\nabla}u{\parallel}^2){\triangle}u+{\alpha}u_t+f(u)=0\;in\;{\Omega}{\times}[0,{\infty}),\\u(x,t)=0\;on\;{\Gamma}_1{\times}[0,{\infty}),\\{\frac{{\partial}u}{\partial{\nu}}}+g(u_t)=0\;on\;{\Gamma}_0{\times}[0,{\infty}),\\u(x,0)=u_0,u_t(x,0)=u_1\;in\;{\Omega}$$ with nonlinear boundary damping by Galerkin approximation benefited from the ideas of Zhang et al. [33]. Furthermore,we overcome some difficulties due to the presence of nonlinear terms $M({\parallel}{\nabla}u{\parallel}^2)$ and $g(u_t)$ by introducing a new variables and we can transform the boundary value problem into an equivalent one with zero initial data by argument of compacity and monotonicity.

• Communications of the Korean Mathematical Society
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• v.38 no.4
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• pp.1045-1061
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• 2023

Using variational methods, Krasnoselskii's genus theory and symmetric mountain pass theorem, we introduce the existence and multiplicity of solutions of a parameteric local equation. At first, we consider the following equation $$\{-div[a(x,{\mid}{\nabla}u{\mid}){\nabla}u]\,=\,{\mu}(b(x){\mid}u{\mid}^{s(x)-2}-{\mid}u{\mid}^{r(x)-2})u\;in\;{\Omega},\\u\,=0\,on\;{\partial}{\Omega},$$ where Ω⊆ ℝ^N is a bounded domain, µ is a positive real parameter, p, r and s are continuous real functions on ${\bar{\Omega}}$ and a(x, ξ) is of type |ξ|^p(x)-2. Next, we study boundedness and simplicity of eigenfunction for the case a(x, |∇u|)∇u = g(x)|∇u|^p(x)-2∇u, where g ∈ L^∞(Ω) and g(x) ≥ 0 and the case $a(x,\,{\mid}{\nabla}u{\mid}){{\nabla}u}\,=\,(1\,+\,{\nabla}u{\mid}^2)^{\frac{p(x)-2}{2}}{\nabla}u$ such that p(x) ≡ p.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.3
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• pp.143-149
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• 2019

In this study, a U-shape composite beam was developed to be effectively used for a steel parking lot which is 8m or lower in height. When the U-shape composite beam was applied to a steel parking lot, essential considerations were story-height and long-span. In addition, due to the mixed structural system with reinforced concrete and steel material, the U-shape composite beam needed to have a structural integrity and reliable performance over demand capacity. The main objective of this study was to investigate the performance of the structure consisting of the reinforced concrete (RC) slab and U-shape beam. A U-shape composite beam generally used at a parking lot served as a control specimen. Four specimens were tested under four-point bending. To calculate theoretical values, strain gauges were attached to rebar, steel plate, and concrete surface in the middle of the specimens. As the results, initial yielding strength of the control specimen occurred at the bottom of the U-shaped steel. After yielding, the specimen reached the maximum strength and the RC slab concrete was finally failed by concrete crush due to compressive stress. The structural performance such as flexural strength and ductility of the specimen with the increased beam depth was significantly improved in comparison with the control specimen. Furthermore, the design of the U-shape composite beam with the consideration of flexural strength and ductility was effective since the structural performance by a negative loading was relatively decreased but the ductile behavior was evidently improved.

• Journal of the Korea Convergence Society
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• v.6 no.4
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• pp.243-248
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• 2015

U-Healthcare is a convergence service with medical care and IT which enables to examine, manage and maintain the patient's health any time and any place. For communication conducted in U-Healthcare service, the transmission methods are used that patient's medical checkup analysis results or emergency data are transmitted to hospital server using wireless communication method. At this moment when the attacker who executes the malicious access makes DRDoS(Distributed Reflection DoS) attack to U-Healthcare devices or BS(Base Station), various damages occur that contextual information of urgent patients are not transmitted to hospital server. In order to deal with this problem, this study suggests DRDoS attack scenario and countermeasures against DRDoS and converges with Big Data which could process large amount of packets. When the attacker attacks U-Healthcare devices or BS(Base Station), DB is interconnected and the attack is prevented if it is coincident. This study analyzes the attack method that could occur in U-Healthcare devices or BS which are remote medical service and suggests countermeasures against the security threat using Big Data.

• The Journal of the Korea institute of electronic communication sciences
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• v.1 no.2
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• pp.127-135
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• 2006

The Korea built successfully e-Korea based on the best of internet infrastructure which was constructed in the world. Continually, Korea is constructing u-City for twenty-first century to enhance the quality of life and to grow up IT industrial. But there is no standard model for u-City because three main builders, central government, local autonomous entities, and communication carriers have respectively their objects, targets and domains. If u-City would be constructed by the common infrastructure for ubiquitous communication, it will be possible to provide any ubiquitous services and compatibility. And the communication infrastructure has to be reflected on the first stage of city planning to reduce high cost for u-City construction. This paper mentions firstly the ranges of communication infrastructure and shows how to construct it each range.

• Journal of Advanced Navigation Technology
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• v.13 no.4
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• pp.577-585
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• 2009

Various studies on individual health-care application services have been lively going on due to recent development of information and communication technology and improvement of life quality. Moreover, U-health care area is emerging as a new growth industry as the demand of U-health care service for a quality life grows with the development of medical technology and ubiquitous environment. U-health care system for crew members on ships, who need to spend much time on sea far from their families, is especially needed because they find their job much more stressful not only physically but also mentally than any other people in different jobs do and have less chance to get proper medical services in time. In this paper, we suggested how to get more accurate and objective U-health wellbeing index by complementing SF-36, the general heath care index model in order to managing health of crew. Also we designed the U-health wellbeing index service system which can provide appropriate sports programs or diet contents according to health index.

• 한국IT서비스학회:학술대회논문집
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• 2009.05a
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• pp.467-470
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• 2009

U-City is the key element of the future knowledge-based society where every citizen will be benefited from the most advanced information technology. The following research reengineers the old process to define the rational and efficient process of the U-City construction project(BPR: Business Process Reengineering). In order to achieve the goal, identify and diagnose problem points, outline the improved plan, and readjust the managing system and process to propose better process. And Lastly, redefine the best efficient process by simple modeling using the UML(Unified Modeling Language). The goal of the systematic proposal is to make contributions to a base of the green growth to be the development of the Sustainable U-City.