• Journal of the Korea Institute of Information Security & Cryptology
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• v.28 no.5
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• pp.1047-1057
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• 2018

As the number of services offered on the Internet exponentially increases, password managers are increasing popular applications that store several passwords in an encrypted database (or password vault). Browser-integrated password managers or locally-installed password managers store the password vault on the user's device. Although a web-based password manager stores the password vault on the cloud server, a user can store the master password used to sign in the cloud server on her device. An attacker that steals a user's encrypted vault stored in the victim's device can make an offline attack and, if successful, all the passwords in the vault will be exposed to the attacker. This paper investigates the vulnerability of the password vault stored in the device and develops attack programs to verify the vulnerability of the password vault.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.30 no.4
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• pp.631-646
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• 2020

The government is pursuing a policy to remove plug-ins for public and private websites to create a convenient Internet environment for users. In general, financial institution websites that provide financial services, such as banks and credit card companies, operate fraud detection system(FDS) to enhance the stability of electronic financial transactions. At this time, the installation software is used to collect and analyze the user's information. Therefore, there is a need for an alternative technology and policy that can collect user's information without installing software according to the no-plug-in policy. This paper introduces the device fingerprinting that can be used in the standard web environment and suggests a guideline to select from various techniques. We also propose a user authentication model using device fingerprints based on machine learning. In addition, we actually collected device fingerprints from Chrome and Explorer users to create a machine learning algorithm based Multi-class authentication model. As a result, the Chrome-based Authentication model showed about 85%~89% perfotmance, the Explorer-based Authentication model showed about 93%~97% performance.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.30 no.4
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• pp.559-572
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• 2020

As internet technology advances, users can share content online, and many sharing services exist. According to a recently published digital forensic study, when playing an online streaming service, you can restore the played video by reconstructing the Chrome cache file left on local device such as a PC. This can be seen as evidence that the user watched illegal video content. From a different point of view, copyright infringement occurs when a malicious user restores video stream and share it to another site. In this paper, we selected 23 online streaming services that are widely used both at home and abroad. After streaming videos, we tested whether we can recover original video using cache files stored on the PC or not. As a result, the paper found that in most sites we can restore the original video by reconstructing cache files. Furthermore, this study also discussed methodologies for preventing copyright infringement in online streaming service.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.8
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• pp.1449-1458
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• 2006

Electronic Navigational Charts (ENCs) are digital charts which contain a great variety of data on coast and sea regions. Although they contain much information that ordinary people are interested in, there is no easy way to access because they are coded in the specialized data forma, and can be visualized by using specialized system. Therefore, supporting systems need to be developed for ordinary people to easily access ENCs. This paper proposes a framework for the ENC systems based on the Web. It relies on quite general standards such as Ceography Markup Language (GML) and Scalable Vector Graphics (SVG). In the framework, ENCs coded in S-57 format are first translated into GML to be stored in a database. Once the database is built, users can request to the database what they want. According to the user request, relevant data are retrieved, and then translated into SVG to be displayed on the Web browser. By using the framework, ordinary people may easily access coast and sea information contained in the ENCs. Furthermore, the framework may provide interoperability by virtue of XML-based standards such as GML and SVG, and efficiency by virtue of database. To validate the feasibility of proposed framework, a prototype system is developed and tested.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.10
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• pp.2324-2330
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• 2010

In middle and high school to learn the principles of fluid mechanics to Experiments in space and time constraints and difficulties for the study of the principles of fluid mechanics to the problem is superficial. In this paper, Pascal's principles, Archimedes' Principle, Bernoulli's Theorem, etc. learning about the fluid mechanics and implemented in Web Browser, In connection with flash and HTML, web simulation is to implement. Web Based Instruction program that implemented a comparative analysis became an effect of 15% to industrial total high school students in satisfaction, Interest, Achievement. The fluid mechanics education through engineering design and web design through the actual web server is implemented on the Internet over broadband. Department of Education, this study the fluid mechanics and the Internet will contribute to the development of distance education.

• The KIPS Transactions:PartD
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• v.11D no.1
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• pp.195-202
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• 2004

This paper describes the development of a window manager based on the real time operating system, Qplus-p, for small internet appliance. Current window managers for small internet appliance are originally developed for desktop environment and then modified for embedded systems. So they have inadequate functions for small internet appliances and do not perfectly support Hangul. The Qplus-P window manager adds the Hangul processing function to Matchbox window manager, a royalty-free window manager for small Internet appliance and provides a new Hangul input method called Amikey. Input mode can be changed automatically from Hangul mode to English mode and vice versa by Amikey. In addition, Qplus-P window manager provides Hangul supported basic applications such as web browser, e-mail client, MP3 player. We developed the window manager by porting open sources to target system after adding Hangul supported functions to them.

• The Transactions of the Korea Information Processing Society
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• v.7 no.9
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• pp.2903-2912
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• 2000

The paper is a design and implementation of the Hybrid Messaging System as integrating electronic mail system and common mail system based on PKI(Public Key Infrastructure), A user writes mail through Web Browser and sends the mail to Web Server. CGHCommon Gateway Interface) program sends the mail that was received through the Web Sever to Post Office Electronic Mail Server using SMTP(SimpleMail Transfer Protocol), The End Process program of the Hybrid Messaging System in a Post Office fetches the mail from the Post Office Electronic Mail Server using POP3 (Post Office Protocol 3), prints it and deliver it to recipients, Also, the Hybrid Messaging System is able to sign the mail with a sign private key that the Certificate Authority publics for users and encrypts the mail with a public key of the Post Office Web Server.

• The KIPS Transactions:PartD
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• v.10D no.4
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• pp.671-678
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• 2003

A digital video is usually very long temporally. requiring large storage capacity. Therefore, users want to watch pre-summarized video before they watch a large long video. Especially in the field of sports video, they want to watch a highlight video. Consequently, highlight video is used that the viewers decide whether it is valuable for them to watch the video or not. This paper proposes how to create soccer video highlight using the structural features of the caption such as temporal and spatial features. Caption frame intervals and caption key frames are extracted by using those structural features. And then, highlight video is created by using scene relocation, logical indexing and highlight creation rule. Finally. retrieval and browsing of highlight and video segment is performed by selection of item on browser.

• KIPS Transactions on Computer and Communication Systems
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• v.5 no.10
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• pp.339-346
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• 2016

1 person media is becoming the leading trend among several media in the Internet era exploiting the individual desire of showing off. But, the vast accessibility of Internet produces the worry about privacy risk, which concludes in the increasement of closed SNS. In this paper, we propose a system based on PWW (Person Wide Web) where a person is producing a media and share it with other persons. PWW is an information system which consists of a smart-phone, mobile anchors, a standard web document, and his own cloud storage. An information consumer gets the link using his smart-phone from the mobile anchors attached on the objects in the field. The web browser in the smart-phone obtains the web documents designated by the link and presents it. We also explains the 1 person media system based on PWW and presents the example utilized in the field. We compared and analyzed the security factor of the system based on between WWW and PWW, and concluded that PWW is better than WWW in the aspect of security.

• Journal of KIISE:Software and Applications
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• v.26 no.12
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• pp.1404-1417
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• 1999

웹과 같은 분산 환경에서는, 웹 브라우저 상에서 SQL 형식의 공간 질의를 수행시키는 것과 또한 서버로부터 그 질의 결과를 보는 것이 가능하다. 그러나, 격자 이미지(raster image)와 같은 대용량 공간 데이타를 포함하는 질의 결과를 웹 브라우징할 때 발생하는 많은 문제점들 중에서, 사용자 응답 시간의 지연은 매우 중요한 문제이다. 본 논문에서는 사용자의 재요청(callback) 접근 패턴이 공간적 근접성(spatial locality)을 따른다는 가정하에서의, 사용자 응답 시간을 최소화하기 위한 새로운 프리페치(prefetch) 전략에 대해서 서술한다. 본 논문의 프리페치 전략은 다음과 같이 요약될 수 있다. 첫째, 프리페치 알고리즘은 사용자의 접근 패턴을 잘 반영하는 힐버트 곡선(Hilbert-curve) 모델을 바탕으로 한다. 둘째, 프리페치 전송 비용을 줄이기 위해서 사용자의 재요청 시간 간격(think time)을 이용한다. 본 논문에서는, 힐버트 곡선을 이용한 프리페치 전략의 성능 평가를 위해서 다양한 실험을 하였으며, 그 결과로 프리페치를 하지 않는 방식보다 높은 성능 향상이 있음을 보인다.Abstract In distributed environment(e.g., WWW), it would be possible for the users to submit SQL-like spatial queries and to see their query results from the server on the Web browser. However, of many obstacles which result from browsing query results including large spatial data such as raster image, the delay of user response time is very critical. In this paper we present a new prefetch policy which can alleviate user response time on the assumption that user's callback access pattern has spatial locality. Our prefetch policy can be summerized as follows: 1) our prefetch algorithm is based on the Hibert-curve model which well replects user's access pattern, and 2) it utilizes user's callback interval to reduce prefetch network transmission cost. In this paper we conducted diverse experiments to show that our prefetch policy achieves higher performance improvement compared to other non-prefetch methods.