• The KIPS Transactions:PartD
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• 제10D권3호
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• pp.375-386
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• 2003

A rapid growth of mobile devices and a proliferation of wireless networks lead to changing the existing environment into a mobile environment. Expansion of mobile environment makes a pressing need of mobile databases, and there are several solutions to achieve it. But they still accompany with some problems. Especially, the current synchronization server that manages consistently many mobile database management systems is based on the centralized method to synchronize data between the mobile database systems. It is the major factor that causes the lower performance of the whole system. Furthermore, the fault tolerance has not been considered in the existing systems. Therefore, we suggest the mobile agent-based mobile database system in order to resolve the problems. The system, we propose in this paper, provides the high-performance of the whole system by mobile grouping, and also may support a fault-tolerance management method.

• Transactions on Electrical and Electronic Materials
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• 제14권3호
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• pp.133-138
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• 2013

Acrylonitrile-butadiene-styrene (ABS) plastic is a polymer material extensively used in electrical and electronic applications. Nickel (Ni) thin film was deposited on ABS by electroless plating, after its surface was treated and modified with atmospheric plasma generated by means of dielectric barrier discharges (DBDs) in air. The method in this study was developed as a pre-treatment for electroless plating using DBDs, and is a dry process featuring fewer processing steps and more environmentally friendliness than the chemical method. After ABS surfaces were modified, surface morphologies were observed using a scanning electron microscope (SEM) to check for any physical changes of the surfaces. Cross-sectional SEM images were taken to observe the binding characteristics between metallic films and ABS after metal plating. According to the SEM images, the depths of ABS by plasma are shallow compared to those modified by chemically treatment. The static contact angles were measured with deionized (DI) water droplets on the modified surfaces in order to observe for any changes in chemical activities and wettability. The surfaces modified by plasma showed smaller contact angles, and their modified states lasted longer than those modified by chemical etching. Adhesion strengths were measured using 3M tape (3M 810D standard) and by 90° peel-off tests. The peel-off test revealed the stronger adhesion of the Ni films on the plasma-modified surfaces than on the chemically modified surfaces. Thermal shock test was performed by changing the temperature drastically to see if any detachment of Ni film from ABS would occur due to the differences in thermal expansion coefficients between them. Only for the plasma-treated samples showed no separation of the Ni films from the ABS surfaces in tests. The adhesion strengths of metallic films on the ABS processed by the method developed in this study are better than those of the chemically processed films.

• The Journal of the Korea Contents Association
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• 제17권2호
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• pp.308-315
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• 2017

This study aims to review the differences and distinctive characteristics between storytelling method of virtual reality contents and storytelling method of conventional contents instead of focusing on economic and industrial effects of virtual reality contents. As a specific target, this study discusses how existing storytelling method of webtoons as a single contents genre can be applied to virtual reality contents when webtoons are adapted into virtual reality contents. The purpose of this study is to find limitations and possibilities for the storytelling technique of virtual reality contents. The results of this study showed that the essence of storytelling in virtual reality contents is in three roles of the users of virtual reality. The users of virtual reality must play the roles of service user, audience of contents, and director of story. This is because the most important storytelling techniques in media contents like editing and change of camera viewpoint can no longer be forced in virtual reality contents. Storytelling techniques in virtual reality contents are much limited compared to the conventional contents in terms of user interaction, expansion of senses, and guarantee of freedom.

• The Journal of the Korea Contents Association
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• 제9권7호
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• pp.57-66
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• 2009

Zigbee is a universal communication standard used in USN and is utilized in various applications. Zigbee protocol provides an address within a single PAN network, and at this time, it uses DAA. This is a method that divides a 16-bit address area into blocks with a fixed size according to the depth to assign one to each node. However, this method is limited because it has to assign addresses in 16 bits. As the depth increases, the number of nodes also increases exponentially to the maximal number of routers provided to each depth. Therefore, it is difficult to construct a huge network with numerous routers and large depth as in the places which are wide or have many shadow areas. Besides, since all the operations are performed in a single PAN network, it is hard to make several PANs into a single network. This article suggests new addressing and routing methods that can construct several PAN networks into a single network and combine broad area with less limitation in the number of routers and depth by extending the Zigbee-based network. Moreover, this paper has tested its performance and has verified its usability through substantive tests.

• Smart Structures and Systems
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• 제6권4호
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• pp.373-388
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• 2010

The updated finite element model of K$\ddot{o}$m$\ddot{u}$rhan Highway Bridge on the Firat River located on the $51^{st}$ km of Elazi$\breve{g}$-Malatya highway is obtained by using analytical and experimental results. The 2D and 3D finite element model of the bridge is created by using SAP2000 structural analyses software, and the dynamic characteristics of the bridge are determined analytically. The experimental measurements are carried out by Operational Modal Analysis Method under traffic induced vibrations and the dynamic characteristics are obtained experimentally. The vibration data are gathered from the both box girder and the deck of the bridge, separately. Due to the expansion joint in the middle of the bridge, special measurement points are selected when experimental test setups constitute. Measurement duration, frequency span and effective mode number are determined by considering similar studies in literature. The Peak Picking method in the frequency domain is used in the modal identification. At the end of the study, analytical and experimental dynamic characteristic are compared with each other and the finite element model of the bridge is updated by changing some uncertain parameters such as material properties and boundary conditions. Maximum differences between the natural frequencies are reduced from 10% to 2%, and a good agreement is found between natural frequencies and mode shapes after model updating.

• Journal of Korea Multimedia Society
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• 제10권11호
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• pp.1417-1426
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• 2007

As one of schemes to protect multimedia content. it is the selective encryption scheme to encrypt partially multimedia content. Compared AES(advanced encryption standard) of traditional encryption, the selective encryption scheme provides low security but is applicable to applications of multimedia content not to require high secrecy. In this paper, we improve the image scrambling scheme proposed by Van De Ville which scrambles an image without bandwidth expansion using DPSS(discrete prolate spheroidal sequence) to make it more secure based on Shujun's research which verifies the secrecy of Van De Ville's scheme. The proposed method utilizes an orthonormalized random matrix instead of Hadamard matrix for secret matrix and to add it for providing high secrecy against statistical attack or known-plaintext attack using some statistical property or estimate of secret matrix from a scrambled image. The experimental results show that the proposed method is more secure than the existing scheme. In addition, we show that the proposed method can be applied to access control or copy control of watermarking application.

• Journal of Agricultural Extension & Community Development
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• 제21권3호
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• pp.181-213
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• 2014

This study analyzes the approach method for the excavation of the outstanding projects in order to improve the ODA quality in the agricultural sector in a situation of the recent quantitative expansion of the Korea's ODA. This analysis is based on the ODA development paradigm of the international society, Korea's ODA development trends, the problems of system, procedure and contents. The analysis drew five approaches, such as an approach based on the strategies, an approach based on the comparative advantage, an approach based on the partnership, an approach based on the networking, an approach of modeling. If each approach method is applied to the excavation of project closely linked to other approach methods, it would be easier to excavate outstanding project. And it could lead to enhancement of project effectiveness. This study introduced the KAPEX program which excavate the customized ODA projects through the application of these approach methods.

• Journal of the Microelectronics and Packaging Society
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• 제27권3호
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• pp.61-67
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• 2020

In this paper, we calculated the warpage of bare substrates and chip attached substrates by using FEM (Finite Element Method), and compared and analyzed the effect of the chips' attachment on warpage. Also, the effects of layer thickness of substrates for reducing warpage were analyzed and the conditions of layer thickness were analyzed by signal-to-noise ratio of Taguchi method. According to the analysis results, the direction of warpage pattern in substrates can change when chips are attached. Also, the warpage decreases as the difference in the CTE (coefficient of thermal expansion) between the top and bottom of the package decreases and the stiffness of the package increases after chips are loaded. In addition, according to the impact analysis of design parameters on substrates where chips are not attached, in order to reduce warpage, the inner layers of the circuit layer Cu1 and Cu4 has be controlled first, and then concentrated on the thickness of the solder resist on the bottom side and the thickness of the prepreg layer between Cu1 and Cu2.

• The KIPS Transactions:PartC
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• 제11C권6호
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• pp.821-828
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• 2004

To analyze the usage information of system and network resources to the each grid application by measuring the real time traffic and calculating the statistic information, we suggested the kernel-based monitoring methods by researching the efficient monitoring method. This method use small system resourcesand measure the monitoring information accurately with less delay than the usual packet capture methods such as tcpdump. Also we implemented the monitoring systems which can monitor the used resources of system and network for grid application using the suggested kernel-based monitoring method. This research can give the useful information to the development of grid application and to grid network scheduler which can assign the proper resources to the grid application to perform efficiently. Network administrator can decide whether the expansion of network is required or not using the monitoring information.

• The KIPS Transactions:PartB
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• 제10B권7호
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• pp.795-802
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• 2003

To live autonomously, intelligent agents such as robots or virtual characters need ability that recognizes given environment, and learns and chooses adaptive actions. So, we propose an action selection/learning mechanism in intelligent agents. The proposed mechanism employs a hybrid system which integrates a behavior-based method using the reinforcement learning and a cognitive-based method using the symbolic learning. The characteristics of our mechanism are as follows. First, because it learns adaptive actions about environment using reinforcement learning, our agents have flexibility about environmental changes. Second, because it learns environmental factors for the agent's goals using inductive machine learning and association rules, the agent learns and selects appropriate actions faster in given surrounding and more efficiently in extended surroundings. Third, in implementing the intelligent agents, we considers only the recognized states which are found by a state detector rather than by all states. Because this method consider only necessary states, we can reduce the space of memory. And because it represents and processes new states dynamically, we can cope with the change of environment spontaneously.