• Applied Chemistry for Engineering
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• v.16 no.1
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• pp.45-51
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• 2005

$K^+-{\beta}^{{\prime}{\prime}}-Al_2O_3$ in the $K_2O-Li_2O-Al_2O_3$ ternary system was synthesized using aluminum nitrate solution as a starting material. For the synthesis of pure $K^+-{\beta}^{{\prime}{\prime}}-Al_2O_3$, raw materials with chemical composition of $0.84K_2O{\cdot}0.082Li_2O{\cdot}5.2Al_2O_3$ were mixed in solution state. The effects of dispersant and solution-pH were investigated in minimizing the particle size and on the synthesis of pure $K^+-{\beta}^{{\prime}{\prime}}-Al_2O_3$. Ethanol was used for a dispersant, and $NH_4OH$ solution and nitric acid were added for pH adjustment. The solution pH was increased from 1.0 to 7.5 by 0.5 increments. Each sample was calcined at $1200^{\circ}C$ for 2 h and characterized with X-ray diffraction and particle size analyzer. The pH of solution significantly effected both particle size and phase formation, while the addition of ethanol only effected particle size. The synthesis of pure $K^+-{\beta}^{{\prime}{\prime}}-Al_2O_3$ was favored by addition of nitric acid (for pH control).

• Proceedings of the Korean Information Science Society Conference
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• 2005.07a
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• pp.817-819
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• 2005

P2P 네트워크의 발달과 DRM 기술의 발전에 힘입어 지적 재산권 소유자와 P2P 네트워크 사용자들에게 있어 P2P를 기반으로 하는 DRM에 대한 발전이 크게 대두되고 있다. 본 논문에서는 pure P2P를 기반으로 하는 DRM 시스템의 설계에 대해 제안한다. 이를 위해 기존에 제안되었던 P2P를 기반으로 하는 DRM 시스템과 라이센스 관리 기법들에 대해서도 아울러 설명함으로써 P2P를 기반으로 하는 DRM 시스템 모델과 효율적인 라이센스 관리 기법을 제시한다.

• Proceedings of the KAIS Fall Conference
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• 2006.05a
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• pp.540-544
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• 2006

사용자가 자료를 직접 송수신하기 위한 P2P 네트워크 환경에는 하이브리드 P2P 네트워크 환경과 순수 P2P 네트워크 환경이 있다. 하이브리드 P2P 네트워크 환경에서 모든 피어들은 서버에 연결되어 있기 때문에, 피어들 간 메시지를 전달할 수 없는 네트워크 고립 상태가 발생되지 않는다. 그러나 순수 P2P 네트워크 환경에서 각 피어들은 서버 없이 서로 직접 연결하여 다른 피어로부터 서비스를 제공받기 때문에, 각 피어들 간의 통신을 중재하는 특정 피어가 종료할 경우 대상 피어들과의 통신이 단절되는 네트워크 고립 현상이 발생될 수 있다. 본 논문에서는 이러한 문제점을 해결하기 위해 각 피어들로 하여금 인접한 피어로부터 IP 주소를 얻어 목록으로 관리하게 함으로써, 연결된 피어가 종료할 경우 목록으로 유지된 IP 주소로 연결하여 네트워크 그룹에 지속적으로 참여할 수 있게 하는 기법을 연구하였다.

• The Pure and Applied Mathematics
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• v.2 no.1
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• pp.35-41
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• 1995

We consider the linear differential equations y〃'＋ P($\chi$)y'＋Q($\chi$)y=0 (1)(y"＋P($\chi$)y)'-Q($\chi$)y =0 (2) Where (2) in the adjoint of (1) and P($\chi$), Q($\chi$) are continuous functions satisfying P($\chi$)$\geq$0, Q($\chi$)$\leq$0, P($\chi$)-Q($\chi$)$\geq$0 on [a, ${\alpha}$). (3) In this, we show that a condition a oscillatory of(1).(omitted)

• The Pure and Applied Mathematics
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• v.17 no.3
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• pp.257-268
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• 2010

We investigate the existence of the following Dirichlet boundary value problem $({\mid}u'\mid^{p-2}u')'\;+\;(p\;-\;1)[\alpha{\mid}u^+\mid^{p-2}u^+\;-\;\beta{\mid}u^-\mid^{p-2}u^-]$ = (p - 1)h(t), u(0) = u(T) = 0, where p > 1, $\alpha$ > 0, $\beta$ > 0 and ${\alpha}^{-\frac{1}{p}}\;+\;{\beta}^{-\frac{1}{p}}\;=\;2$, $T\;=\;{\pi}_p/{\alpha}^{\frac{1}{p}}$, ${\pi}_p\;=\; \frac{2{\pi}}{p\;sin(\pi/p)}$ and $h\;{\in}\;L^{\infty}$(0,T). The results of this paper generalize some early results obtained in [8] and [9]. Moreover, the method used in this paper is elementary and new.

• The Pure and Applied Mathematics
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• v.7 no.2
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• pp.79-86
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• 2000

In this paper, we introduce the classes H(p,q,k),K(p;k) of operators determined by the Heinz-Kato-Furuta inequality and Holer-McCarthy inequality. We characterize relationship between p-quasihyponormal, $\kappa$-quasihyponormal and $\kappa$-p-quasihyponormal operators. And it is proved that every operator in K(p;1) for some $0 is paranormal.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2005.05a
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• pp.477-482
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• 2005

Recently, client computing trend has been changed from server oriented information application to network based P2P(Peer to Peer) services. The conventional client/server method has the merit of accessing abundant information, on the other side P2P has the merit of synchronized community support and information exchange. P2P has four meaning of point to point, peer to peer, person to person and path to profitability. In manufacturing system field, the second meaning is interested. P2P is classified to three type such as conventional client/server, hybrid P2P and pure P2P. The third is really peer to peer concept. The related technologies with P2P are P2P searching, XML, cooperation, IPv6, computing sharing and P2P communication. This paper describes the scheme of P2P and related contents. And through the P2P based technology, a P2P-based collaborative machine and a vertical portal machine are introduced in this paper. The scheme of the machines mentioned above is suggested for cooperation in manufacturing system and u-Manufacturing.

• The KIPS Transactions:PartA
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• v.11A no.4
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• pp.257-266
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• 2004

Mobile agents are defined as processes which can be autonomously delegated or transferred among the hosts in a network in order to perform some computations on behalf of the user and co-operate with other agents. Currently, mobile agents are used in various fields, such as electronic commerce, mobile communication, parallel processing, search of information, recovery, and so on. In pure P2P network environment, if mobile agents that require computing resources rashly migrate to another peers without consideration on the peer's capacity of resources, the peer may have a problem that the performance of the peer is degraded due to lack of resources. To solve this problem, we propose resource reservation based load balancing scheme of using RMA(Resource Management Agent) that monitors workload information of the peers and that decides migrating agents and destination peers. In mobile agent migrating procedure, if the resource of specific peer is already reserved, our resource reservation scheme prevents other mobile agents from allocating the resource.

• Journal of Periodontal and Implant Science
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• v.32 no.4
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• pp.697-709
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• 2002

The present study was performed to evaluate the effect of citric acid on the change of implant surface microstructure according to application time. Implants with pure titanium machined surface, titanium plasma-sprayed surface, and sand-blasted, large grit, acid etched surface were utilized. Implant surface was rubbed with pH 1 citric acid for $\frac{1}{2}$ min., 1 min., 1 $\frac{1}{2}$ min., 2 min., and 3min, respeaively in the test group and implant surface was not treated in the control group. Then, the specimens were processed for scanning electron microscopic observation. The following results were obtained. 1. Both test and control group showed a few shallow grooves and ridges in pure titanium machined surface implants. There were not significant differences between two groups. 2. In titanium plasma-sprayed surfaces, round or amorphous particles were deposited irregularly. The irregularity of titanium plasma-sprayed surfaces conditioned with pH 1 citric acid was lessened and the cracks were increased relative to the application time of pH 1 citric acid. 3. Sand-blasted, large grit, acid etched surfaces showed the macro/micro double roughness. The application of pH 1 citric acid didn't change the characteristics of the sand-blasted, large grit, acid etched surfaces. In conclusion, the application of pH 1 citric acid to titanium plasma-sprayed surface is improper. And pure titanium machined surface implants and sand-blasted, large grit, acid etched surface implants can he treated with pH 1 citric acid for peri-implantitis treatment if the detoxification of these surfaces could be evaluated.

• The Pure and Applied Mathematics
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• v.17 no.2
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• pp.167-173
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• 2010

In this paper, we introduce the concept of a weakly P-space which is a generalization of a P-space and prove that for any covering map f : $X{\rightarrow}Y$, X is a weakly P-space if and only if Y is a weakly P-space. Using these, we investigate the minimal basically disconnected cover of weakly P-spaces and their products.