• Annual Conference on Human and Language Technology
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• 1993.10a
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• pp.47-57
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• 1993

현재 국내에서 한국형 정보 검색 시스템의 중요성을 인식하고, 이를 국내 기술로 구축하려는 여러 시도들이 진행중에 있다. 이 가운데 정보 검색 시스템 구축에 기반이 되는 정보 저장 하부 구조로서, 한글 문서를 위한 효율적인 문서 검색 기법에 대한 연구는 필수적이다. 본 논문에서는 이를 위해 파일 기법을 이용한 한글 문서 검색 기법을 설계한다. 아울러, 제안된 기법을 토대로 실제 시스템을 구현하여 성능을 분석하였다.

• Journal of Internet of Things and Convergence
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• v.1 no.1
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• pp.33-38
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• 2015

Hardware are developed in various architecture. It is necessary to verifying value of variables in modules generated in each clock cycles for timing simulation. In this paper, a test vector generator in software type generates test vectors for timing simulation of 224-bit ECDSA hardware modules in developing stage. It provides test vectors with GUI format and text file format.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.24 no.5
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• pp.781-793
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• 2014

A Public Key Infrastructure (PKI) is security standards to manage and use public key cryptosystem. A PKI is used to provide digital signature, authentication, public key encryption functionality on insecure channel, such as E-banking and E-commerce on Internet. A soft-token private key in PKI is leaked easily because it is stored in a file at standardized location. Also it is vulnerable to a brute-force password attack as is protected by password-based encryption. In this paper, we proposed a new method that detects private key compromise and is probabilistically secure against a brute-force password attack though soft-token private key is leaked. The main idea of the proposed method is to use a genuine signature key pair and (n-1) fake signature key pairs to make an attacker difficult to generate a valid signature with probability 1/n even if the attacker found the correct password. The proposed method provides detection and notification functionality when an attacker make an attempt at authentication, and enhances the security of soft-token private key without the additional cost of construction of infrastructure thereby extending the function of the existing PKI and SSL/TLS.

• Journal of KIISE:Computing Practices and Letters
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• v.14 no.6
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• pp.589-593
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• 2008

These days, as a side effect of the growth of the mobile devices, malwares for the mobile devices also tend to increase and become more dangerous. Because embedded Linux is one of the advanced OSes on mobile devices, a solution to preventing malwares from infecting and destroying embedded Linux will be needed. We present a scheme using signature verification for embedded Linux that prevents executallle-Infecting malwares. The proposed scheme works under collaboration between mobile devices and a server. Malware detection is delegated to the server. In a mobile device, only integrity of all executables and dynamic libraries is checked at kernel level every time by kernel modules using LSM hooks just prior to loading of executables and dynamic libraries. All procedures in the mobile devices are performed only at kernel level. In experiments with a mobile embedded device, we confirmed that the scheme is able to prevent all executable-Infecting malwares while minimizing damage caused by execution of malwares or infected files, power consumption and performance overheads caused by malware check routines.

• Journal of KIISE
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• v.45 no.2
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• pp.106-112
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• 2018

Recently, the number of cyber attacks using malicious code has increased. Various types of malicious code detection techniques have been researched for several years as the damage has increased. In recent years, profiling techniques have been used to identify attack groups. This paper focuses on the identification of attack groups using a detection technique that does not involve malicious code detection. The attacker is identified by using a string or a code signature of the malicious code. In addition, the detection rate is increased by adding a technique to confirm the packing file. We use Yara as a detection technique. We have research about RAT (remote access tool) that is mainly used in attack groups. Further, this paper develops a ruleset using malicious code and packer main feature signatures for RAT which is mainly used by the attack groups. It is possible to detect the attacker by detecting RAT based on the newly created ruleset.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.24 no.5
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• pp.885-896
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• 2014

The files in computer storages can be deleted due to unexpected failures or accidents. Some malicious users often delete data by himself for anti-forensics. If deleted files are associated with crimes or important documents in business, they should be recovered and the recovery tool is necessary. The recovery methods and tools for some filesystems such as NTFS, FAT, and EXT have been developed actively. However, there has not been any researches for recovering deleted files in XFS filesystem applied to NAS or CCTV. In addition, since the current related tools are based on the traditional signature detection methods, they have low recovery rates. Therefore, this paper suggests the recovery methods for deleted files based on metadata and signature detection in XFS filesystem, and verifies the results by conducting experiment in real environment.

• 전자공학회논문지 IE
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• v.43 no.1
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• pp.46-51
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• 2006

Recently, smart card system which is known as easy to portable and also safe from physical, electrical, and software attack is observed to manage information that becomes the target of security in safety. And java card graft upon java technology to smart card platform is having very good advantage with object-oriented techniques and also, java card have the open type OS that can show the same action in different hardware characteristic which allows various application programs. In this paper, we introduced independent execution characteristic of java platform because being set to each smart card was uncomfortable till now and we designed access control member card that allows several administrators in different access privilege by single card using java card. Several administrators can approach to various information of file type that is included on issued card to user by using different PIN. In the proposed method, confirmation of personal information, administration contents update, demand by contents, is possible by single card. At this moment, wish to do safer user certification that improve security limitation which is from PIN, used for user certification, and signature data. In the proposed method, as design and implementation of utilization technology of java card, biometrics, user certification which uses multi PIN, provide that more safety and conveniently.

• KIPS Transactions on Computer and Communication Systems
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• v.6 no.2
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• pp.87-94
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• 2017

Microsoft Office is an office suite of applications developed by Microsoft. Recently users with malicious intent customize Office files as a container of the Malware because MS Office is most commonly used word processing program. To attack target system, many of malicious office files using a variety of skills and techniques like macro function, hiding shell code inside unused area, etc. And, people usually use two techniques to detect these kinds of malware. These are Signature-based detection and Sandbox. However, there is some limits to what it can afford because of the increasing complexity of malwares. Therefore, this paper propose methods to detect malicious MS office files in Computer forensics' way. We checked Macros and potential problem area with structural analysis of the MS Office file for this purpose.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.29 no.4
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• pp.775-784
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• 2019

Malware infringement attacks are continuously increasing in various environments such as mobile, IOT, windows and mac due to the emergence of new and variant malware, and signature-based countermeasures have limitations in detection of malware. In addition, analytical performance is deteriorating due to obfuscation, packing, and anti-VM technique. In this paper, we propose a system that can detect malware based on machine learning by using similarity hashing-based pattern detection technique and static analysis after file classification according to packing. This enables more efficient detection because it utilizes both pattern-based detection, which is well-known malware detection, and machine learning-based detection technology, which is advantageous for detecting new and variant malware. The results of this study were obtained by detecting accuracy of 95.79% or more for benign sample files and malware sample files provided by the AI-based malware detection track of the Information Security R&D Data Challenge 2018 competition. In the future, it is expected that it will be possible to build a system that improves detection performance by applying a feature vector and a detection method to the characteristics of a packed file.

• Journal of Korea Spatial Information System Society
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• v.9 no.1
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• pp.59-77
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• 2007

Advances in mobile techknowledges and supporting techniques require an effective representation and analysis of moving objects. Similarity search of moving object trajectories is an active research area in data mining. In this paper, we propose a trajectory search algorithm for spatio-temporal similarity of moving objects on road network. For this, we define spatio-temporal distance between two trajectories of moving objects on road networks, and propose a new method to measure spatio-temporal similarity based on the real road network distance. In addition, we propose a similar trajectory search algorithm that retrieves spatio-temporal similar trajectories in the road network. The algorithm uses a signature file in order to retrieve candidate trajectories efficiently. Finally, we provide performance analysis to show the efficiency of the proposed algorithm.