• Journal of Internet Computing and Services
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• v.12 no.4
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• pp.135-143
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• 2011

The smartphone allows learners to be involved in learning environments in which students actively study from anywhere and at anytime. Because learners can keep engaged in the environment where they can access to the internet, they can efficiently study in transit using various features and functions of smartphone. Smart learning is a unique learning based on mobility and functions of mobile digital devices including searching and sharing information and using various applications. For the effective use of smartphones in e-learning systems, the contents and learning management systems should be designed to meet effective teaching and learning principles, such as interactivity and collaborations. In smart learning, learning contents for effective learning need to be integrated with typical functions of smartphones and to develop small pieces of learning contents according to learning topics. In the case of learning management systems, it should reflect understanding of learners' environment using a PA agent program and provide personalized learning services.

• Journal of Internet Computing and Services
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• v.11 no.6
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• pp.87-110
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• 2010

Recently competitive Korean companies are suffered from financial loss due to illegal exposure of their own proprietary know-how secrets, since it is difficult to watch hidden illegal channels to leak them due to their digitalization. Today the DRM-based system designed to protect such secrets is insufficient to prevent it, since DRM-based protection system cannot defend the intelligent robbery of secrets, in special, employee's robbery. The MSEC is much appropriate to secure secrets against employee's robbery. Our paper notes that IGMP, MSEC and SNMP can work easily together to realize secure system that satisfy strong security condition for prevention from leaking secrets. Since the previous research was on the architectural design for prevention of illegal exposure, this paper proposes the efficient protocol based on MSEC protocol. Our protocol satisfies the strong security conditions that the principles that the secret should be stored/distributed only in an encrypted shape, and should be separated physically from its encryption key, and should be carried in registered mobile storage separate from its processing device, and should be verified in terms of both user and device. Thus this paper proposes both the protocol for secret document distribution and its group key management.

• Journal of Internet Computing and Services
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• v.11 no.3
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• pp.43-51
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• 2010

In this paper, we evaluate the system throughput and the method of optimal wireless resource allocation for the access zone (AZ) and relay zone (RZ) in downlink when the cell coverage is extended using the non-transparent Relay Station (RS) in a 2-hop cellular relay system based on IEEE802.16j, which uses the OFDMA-TDD structure. For the analyses, we first introduce the MAC (Media Access Control) frame structure in the non-transparent mode, then we investigate the interfering elements in both AZ and RZ for the network devices such as the Mobile Station (MS) and RS. Through computer simulation, we analyze the cell coverage extension and system throughput in terms of the distance between Base Station (BS) and RS, then we present the amount of the optimal allocation of wireless resource for the AZ and RZ in downlink using our results.

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.12
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• pp.1234-1238
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• 2010

In recent, there have been done many studies on applications that monitor the information of mobile objects using Wireless Sensor Networks (WSN). A density query that finds out an area spread by density that a target object requires in the whole sensing field is a field of object monitoring applications. In this paper, we propose a novel homogeneous network-based in-network density query processing scheme that significantly reduces query processing costs and assures high accuracy. This scheme is based on the possibility-based expected region selection technique and the result compensation technique in order to enhance the accuracy of the density query and to minimize its energy consumption. To show the superiority of our proposed scheme, we compare it with the existing density query processing scheme. As a result, our proposed scheme reduces about 92% energy consumption for query processing, while its network lifetime increases compared to the existing scheme. In addition, the proposed scheme guarantees higher accuracy than the existing scheme in terms of the query result.

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.12
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• pp.1154-1164
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• 2010

As an useful application in broadcasting services, the targeting service has been mainly studied to improve the service satisfaction and user usage in various media service environments based on user profile, preferences, and usage history. Targeting service is expanding its domain from broadcasting contents to interstitial contents and from fixed TV devices to mobile devices. Service data also include advertisement data, coupon, and information about media contents as well as simple broadcasting data. In this paper, the targeting data service is designed and implemented on articles, advertisement and broadcasting information on the basis of the user information. To adapt this to web-based media contents, information on user profile, preferences, and usage history is newly defined on the basis of the user metadata developed in TV-Anytime Forum and the user information defined in OpenSocial. The targeting data service is implemented to generate user preferences information and usage history pattern based on the similarity among user preference, contents information, and usage history. Based on performance evaluation, we prove that the proposed targeting data service is effectively applicable to web-based media contents as well as broadcasting service.

• 한국HCI학회:학술대회논문집
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• 2009.02a
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• pp.52-55
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• 2009

With the recent development of virtual reality, it has been actively investigated to develop user interfaces for immersive interaction. Immersive user interfaces improve the efficiency and the capability of information processing in the virtual environment providing various services, and provide effective interaction in the field of ubiquitous and mobile computing. In this paper, we propose an virtual reality platform "My Workspace" which renders an 3D virtual workspace by using an immersive user interface. We develop an interface that integrates an optical see-through head-mounted display, a Wii remote controller, and a helmet with infrared LEDs. It estimates the user's gaze direction in terms of horizontal and vertical angles based on the model of head movements. My Workspace expands the current 2D workspace based on monitors into the layered 3D workspace, and renders a part of 3D virtual workspace corresponding to the gaze direction. The user can arrange various tasks on the virtual workspace and switch each task by moving his head. In this paper, we will also verify the performance of the immersive user interface as well as its usefulness with the usability test.

• Journal of Internet Computing and Services
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• v.6 no.3
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• pp.45-54
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• 2005

Recently, researches on various base technologies for wireless Internet services have been conducted. In the WAP (Wireless Application Protocol) Forum, a WAP gateway which does mutual conversion between existent wired Internet protocols and WAP protocols was proposed. In this paper, CSA(Client Side Agent) and SSA(Server Side Agent) for WAP gateway environments are designed and implemented, as a way of improving communication efficiency in such restrictive environments as wireless communications. Located on mobile WAP devices(CSA) and a WAP Gateway(SSA), the agents perform communication efficiency improvement activities such as a packet header reduction mechanism and a data reduction mechanism using data differencing analysis in order to reduce the size of data transmission in wireless communication environments. The Internet phone emulator of Phone.com is used in order to make sure that the implemented agents work correctly, Experimental results show that the implemented agents reduce the size of data transmission significantly.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.23 no.2
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• pp.147-155
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• 2013

Proxy re-encryption scheme has advantage where plaintext does not get exposed during re-encryption process. This scheme is popular for sharing server-saved data in case of cloud computing or mobile office that uses server to save data. Since previous proxy re-encryption schemes can use re-encryption key over and over again, it may abuse re-encryption. To solve this problem, conditional proxy re-encryption scheme was proposed. But, it is computationally expensive generate the same number of re-encryption key with the number of condition values. In this paper, we propose an efficient conditional proxy re-encryption scheme in terms of re-encryption key generation. The proposed scheme uses only encryption and decryption process. Therefore it has advantage to generate one re-encryption key for one person. The proposed scheme is secure against chosen-ciphertext attack.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.8
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• pp.1401-1406
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• 2006

Mobile Ad-hoc networks have recently attracted a lot of attention in the research community as well as in industry. Although the previous research mainly focused on various of Ad-hoc in routing, we consider, in this paper, how to efficiently support applications such as variable Goocasting basd on Ad-hoc networks. The goal of a geocasting uotocol is deliver data packets to a group of nodes that are located within a specified geocasting region. Previous research that support geocast nice in mobilie computing based on Ad-hoc have the non-optimization problem of data delivery path, overhead by frequent reconstruction of the geocast tree, and service disruption problem. In this paper, we propose the mobility pattern based geocast technique using variable service range according to the nobility of destination node and resource reservation to solve this problem. The experimental results show that our proposed mechanism has improved performance of Connection & Network Overhead than previous research.

• Journal of Navigation and Port Research
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• v.40 no.6
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• pp.369-374
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• 2016

Recently, due to the rapid development of smart computing technology, there have been a lot of studies on 3D navigation, and consequently the advanced commercial 3D navigation system and 3D VTS system are on the market. Even the 3D technology is well known and wide spreaded, unfortunately, the secret of code behind is still unleashed. The purpose of this paper is to show the basic methodologies to display ENC features under 3D display environment to meet the requirement of S-52 standards. The OpenGL ES is used to develop 3D ENC Viewer for further use on mobile platforms and web based vessel monitoring system. P articularly, area object triangulation, complex line drawing, polygon pattern filling and symbol drawing by texture mapping are explained in detail. The result of performance test is shown as table for correlation of SENC file size to display speed.