• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.04a
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• pp.556-560
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• 2002

In this paper, we propose a remote controller for robot manipulator using local area network(LAN) and internet. To do this, we develope a server-client system as used in the network field. The client system is in any computer in remote place for the user to log-in the server and manage the remote factory. the server system is a computer which controls the manipulator and waits for a access from client. The server system consists of several control algorithms which is needed to drive the manipulator and networking system to transfer images that shows states of the work place, and to receive a Tmp data to run the manipulator The client system consists of 3D(dimension) graphic user interface for teaching and off-line task like simulation, external hardware interface which makes it easier for the user to teach. Using this server-client system, the user who is on remote place can edit the work schedule of manipulator, then run the machine after it is transferred and monitor the results of the task.

• Journal of the Korea Society of Computer and Information
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• v.26 no.6
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• pp.115-127
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• 2021

It is not an easy task for a user to find the correct documents that a user really wanted at once from a vast amount of the search results. For this reason, various methods of recommending documents by taking the user's preferences into consideration based on the user's document browsing history have been proposed. However, the document recommendation methodology based on the document browsing history also has a limitation that only the information the user has viewed is utilized, but the intent of the user searching for the document is not fully utilized. Therefore, we propose a document recommendation method based on the user's search intent that utilizes information on "Why" the user reads the document, instead of the information on "Who" reads the document. In order to confirm the feasibility of the proposed methodology, an experiment was conducted by analyzing 239,438 actual user's search history of one of the most popular e-commerce platform companies in Korea. As a result, our methodology showed superior performance compared to the existing content-based or simple browsing history-based recommendation model.

• Journal of the Korea Society of Computer and Information
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• v.22 no.12
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• pp.117-123
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• 2017

The personalized search algorithm is a search system that analyzes the user's IP, cookies, log data, and search history to recommend the desired information. As a result, users are isolated in the information frame recommended by the algorithm. This is called 'Filter bubble' phenomenon. Most of the personalized data can be deleted or changed by the user, but data stored in the service provider's server is difficult to access. This study suggests a way to neutralize personalization by keeping on sending random query words. This is to confuse the data accumulated in the server while performing search activities with words that are not related to the user. We have analyzed the rank change of the URL while conducting the search activity with 500 random query words once using the personalized account as the experimental group. To prove the effect, we set up a new account and set it as a control. We then searched the same set of queries with these two accounts, stored the URL data, and scored the rank variation. The URLs ranked on the upper page are weighted more than the lower-ranked URLs. At the beginning of the experiment, the difference between the scores of the two accounts was insignificant. As experiments continue, the number of random query words accumulated in the server increases and results show meaningful difference.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.7
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• pp.693-701
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• 2002

In this paper, we analyze the coverage of asynchronous IMT(International Mobile Telecommunication)-2000 reverse link with a MUD(Multi-User Detector) system. The MUD system is utilized to increase the coverage of reverse link. Also we have considered a propagation loss model and an interference effect. Because it is very difficult that we have calculated the interference accurately, so a fractional cell loading factor(F) is used in this paper. We make use of a MUD efficiency($\beta$) to analyze the performance; this efficiency is presented the MAI of reduction. A simulation utilizes Hata's model, we calculated the coverage according to voice and data services. In this paper, we have assumed that the frequency of carrier has 800 MHz or 1.9 GHz, and a bandwidth is decided 3.84 MHz. We have predicted the performance of actual system by the analysis of capacity and coverage.

• Journal of Communications and Networks
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• v.14 no.5
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• pp.471-480
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• 2012

Reliable detection of primary user activity increases the opportunity to access temporarily unused bands and prevents harmful interference to the primary system. By extracting a global decision from local sensing results, cooperative sensing achieves high reliability against multipath fading. For the effective combining of sensing results, which is generalized by a likelihood ratio test, the fusion center should learn some parameters, such as the probabilities of primary transmission, false alarm, and detection at the local sensors. During the training period in supervised learning, the on/off log of primary transmission serves as the output label of decision statistics from the local sensor. In this paper, we extend unsupervised learning techniques with an expectation maximization algorithm for cooperative spectrum sensing, which does not require an external primary transmission log. Local sensors report binary hard decisions to the fusion center and adjust their operating points to enhance learning performance. Increasing the number of sensors, the joint-expectation step makes a confident classification on the primary transmission as in the supervised learning. Thereby, the proposed scheme provides accurate parameter estimates and a fast convergence rate even in low signal-to-noise ratio regimes, where the primary signal is dominated by the noise at the local sensors.

• Convergence Security Journal
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• v.23 no.4
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• pp.43-52
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• 2023

Many businesses and organizations use smartcard-based user authentication for remote access. In the meantime, through various studies, dynamic ID-based remote user authentication protocols for distributed multi-server environments have been proposed to protect the connection between users and servers. Among them, Qiu et al. proposed an efficient smart card-based remote user authentication system that provides mutual authentication and key agreement, user anonymity, and resistance to various types of attacks. Later, Andola et al. found various vulnerabilities in the authentication scheme proposed by Qiu et al., and overcame the flaws in their authentication scheme, and whenever the user wants to log in to the server, the user ID is dynamically changed before logging in. An improved authentication protocol is proposed. In this paper, by analyzing the operation process and vulnerabilities of the protocol proposed by Andola et al., it was revealed that the protocol proposed by Andola et al. was vulnerable to offline smart card attack, dos attack, lack of perfect forward secrecy, and session key attack.

• Journal of Convergence for Information Technology
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• v.11 no.2
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• pp.1-9
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• 2021

OASIS(Online Archiving & Searching Internet Sources) is a web archiving project of the National Library of Korea started in 2004 to systematically collect, manage, and preserve online digital information resources. In this study, the following problems were derived by analyzing the access log of the OASIS website and conducting a user survey. First, people's awareness of the OASIS project was very low, and there were many first-time visitors to the website. Second, active promotion and service reorganization to improve the use of OASIS was insufficient. The study suggested that the improvement point of this was to strengthen its own direct promotion and indirect promotion in connection with other agencies. In addition, it was proposed to enhance the service through user-customized services and to reinforce content that induces interest and fun.

• Proceedings of the Korea Multimedia Society Conference
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• 2012.05a
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• pp.402-403
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• 2012

최근 정보화 사회 발전에 따라 기업 비밀의 유출사고가 빈번하게 발생하고 있으며 지식 정보의 가치가 커짐에 따라 기업의 피해도 같이 증가하고 있다. 외부의 공격으로 개인 또는 기업의 중요한 정보가 유출되거나 정당하지 않은 목적으로 수집, 가공되어 오/남용되어 정보의 악영향을 초래하고 있기 때문에 효율적으로 기업 정보를 관리하는 방법을 요구하고 있다. 본 논문에서는 사용자 인증과 문서 접근 시 자신의 보안 등급과 관련 부서를 확인하고 사용자 등급에 맞는 OTP(One-Time Pad)를 부여하여 사용자 등급에 맞는 문서만을 열람할 수 있다. 또한 문서의 무결성 보장과 문서 열람 Log를 통해 효율적이고 안전하게 접근 통제를 할 수 있다.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.27 no.1
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• pp.5-14
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• 2017

Many web services which use OAuth Protocol offer users to log in using their personal profile information given by resource servers. This method reduces the inconvenience of the users to register for new membership. However, at the time a user finishes using OAuth client web service, even if he logs out of the client web service, the resource server remained in the login state may cause the problem of leaking personal information. In this paper, we propose a solution to mitigate the threat by providing an additional security behavior check: when a user requests to log out of the Web Client service, he or she can make decision whether or not to log out of the resource server via confirmation notification regarding the state of the resource server. By utilizing the proposed method, users who log in through the OAuth Protocol in the public PC environment like department stores, libraries, printing companies, etc. can prevent the leakage of personal information issues that may arise from forgetting to check the other OAuth related services. To verify our study, we implement a Client Web Service that uses OAuth 2.0 protocol and integrate it with our security behavior check. The result shows that with this additional function, users will have a better security when dealing with resource authorization in OAuth 2.0 implementation.

• Journal of KIISE:Computer Systems and Theory
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• v.36 no.6
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• pp.463-475
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• 2009

Flash memory is suitable for real time systems because of its consistent performance for random access, low power consumption and shock resistance. However, flash memory needs blocking time to perform a garbage collection to reclaim invalidated pages. Moreover, the worst-case garbage collection time is significantly longer than the best-case garbage collection time. In this paper, we propose a FTL (Flash Translation Layer) mapping scheme called KAST (K-Associative Sector Translation). In the KAST scheme, user can control the maximum association of the log block to limit the worst-case garbage collection time. Performance evaluation using simulation shows that not only KAST completes the garbage collection within the specified time but also provides about 10~15% better average performance than existing FTL schemes.