• Journal of Internet Computing and Services
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• v.10 no.4
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• pp.223-230
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• 2009

Among the remote user authentication schemes, password-based authentication methods are the most widely used. In 2004, Das et al. proposed a "Dynamic ID Based Remote User Authentication Scheme" that is the password based scheme with smart-cards, and is the light-weight technique using only one-way hash algorithm and XOR calculation. This scheme adopts a dynamic ID that protects against ID-theft attack, and can resist replay attack with timestamp features. Later, many flaws of this scheme were founded that it allows any passwords to be authenticated, and can be vulnerable to impersonation attack, and guessing attack. By this reason many modifications were announced. These scheme including all modifications are similarly maintained security against replay the authentication message attack by the timestamp. But, if advisory can replay the login immediately, this attempt can be succeeded. In this paper, we analyze the security vulnerabilities of Das scheme, and propose improved scheme which can resist on real-time replay attack using the counter of authentication. Besides our scheme still secure against impersonation attack, guessing attack, and also provides mutual authentication feature.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.7B
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• pp.649-658
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• 2009

Due to limited size and limited battery lifetime of sensor node, one has to address the power saving issue in wireless sensor network. The existing power saving algorithm based on data reuse was proposed for the cluster structured wireless sensor network. We state the problem of existing power saving algorithm and propose new power saving algorithm for tree structured wireless sensor network. The proposed algorithm reduces power consumption by buffering the sensed data at the selected relay node for its data lifetime. The optimum buffering node is selected so that the power saving gain is maximized and at the same time, power consumption among sensor nodes are equally distributed in the network. With computer simulations, it is shown that the proposed algorithm outperforms the conventional algorithm in terms of power saving gain.

• The Journal of the Korea Contents Association
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• v.8 no.1
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• pp.203-211
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• 2008

Due to the advent of presumer and digital production of moving picture, a lot of UCC has been generated by editing the previous moving pictures in various way. It causes a lot of problems on copyright, duplication, and content. In reorganizing the contents, it is necessary to increase productivity and reusability by managing production pipeline systematically through the standardization of moving picture content. For this purpose, we try to develop the moving picture content management system that can manage all kinds of information on the production pipeline, based on SCORM of e-learning by considering production, publication and re-editing. Using the meta-data of content object, user and producer can easily search and reuse the contents. Hence, they can choose the contents object according to their preference and reproduce their own creative UCC by reorganizing and packaging the selected objects. The management of copyright by the unit of scene would solve the problem of copyright. The sequencing technique of SCORM as an interactive storytelling method makes it possible to produce individual contents by user's preference.

• Journal of Internet Computing and Services
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• v.19 no.3
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• pp.15-23
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• 2018

A code reuse attack is an attack technique that can execute arbitrary code without injecting code directly into the stack by combining executable code fragments existing in program memory and executing them continuously. ROP(Return-Oriented Programming) attack is typical type of code reuse attack and serveral defense techniques have been proposed to deal with this. However, since existing methods use Rule-based method to detect attacks based on specific rules, there is a limitation that ROP attacks that do not correspond to previously defined rules can not be detected. In this paper, we introduce a method to detect ROP attack by learning command pattern used in ROP attack code using RNN(Recurrent Neural Network). We also show that the proposed method effectively detects ROP attacks by measuring False Positive Ratio, False Negative Ratio, and Accuracy for normal code and ROP attack code discrimination.

• Journal of the Korea Society for Simulation
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• v.21 no.3
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• pp.35-42
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• 2012

Defense Modeling and Simulation aims to provide a computerized war environment where we can analyze weapon systems realistically. As we invest significant efforts to represent weapon systems and their operational environments on the computer, there has been an increasing need to reuse predefined weapon models. In this paper, we introduce OB-Cloud (Ontology-Based Cloud storage) to utilize predefined weapon models. OB-Cloud has been implemented as a repository for OpenSIM (Open Simulation engine for Interoperable Models), which is an integrated simulation environment for aiding weapons effectiveness analysis, under the development of our research team. OB-Cloud uses weapon ontology and thesaurus dictionaries to provide semantic search for reusable models. In this paper, we present repository services of OB-Cloud, including registration of weapon models and semantic retrieval of similar models, and illustrate how we can improve reusability of weapon models, through an example.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.7
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• pp.1391-1396
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• 2012

It is introduced an approach to model for numerical analysis of a sound absorbing material that has different absorbing coefficient according to frequency. For modeling of a sound absorbing material, we tried to model by a traditional modeling method. But it had large differences on frequency domain, especially a capacitance component due to increasing of frequency. We approach to model a sound absorbing material by the Debye polarization technique with non-linear least square method. At first, we estimated parameters form a polyurethane with thickness 25 mm, then we could model a polyurethane with thickness 50 mm using same parameters. Therefor, we could find that the Debye polarization is an useful way to model sound absorbing materials.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.457-457
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• 2015

최근, 우리나라에서는 효과적인 수자원 관리와 추가적인 수원 확보 차원에서 빗물 재이용에 관한 관심이 크게 증대되고 있다. 하지만 국내의 관련된 제도와 기술 지침은 단지 규제 측면에서 빗물이용시설을 설치하도록 제시하고 있어 빗물이용시설의 실제 사용을 고려한 계획이 배제되어 있다. 본 연구의 목적은 실용적인 빗물이용시설의 계획을 위해 SWMM을 이용하여 빗물 재이용의 수요(빗물 재이용 목표량)와 공급(연간 강우량과 패턴)을 반영한 설계 방법을 제시하는 것이다. 이를 위해 SWMM 내에 구현되어 있는 빗물통 모의에 관한 수식을 이용하되, 수식을 목적에 맞도록 일부 변형하여 활용하였다. 그리고 빗물이용시설의 규모는 설정한 목표량을 만족할 수 있는 최소의 크기로 결정하는 것이 적절하고, 장기간의 강우자료를 이용한 물수지 석이 요구되므로 이를 고려하였다. 본 연구에서 제시한 빗물이용시설의 설계 방법은 송산 그린시티 동측지구에 계획된 빗물이용시설의 규모 결정에 활용되었다. 빗물 재이용의 목표량이 일정한 경우, 빗물이용시설의 크기가 커질수록 빗물 재이용 가능량은 로그함수의 형태로 증가하여, 빗물이용시설이 특정 규모 이상으로 커지더라도 빗물 재이용 가능량은 더 이상 증가하지 않는 임계점이 나타난다(그림 1). 따라서 빗물이용시설은 이러한 임계점이 나타나는 규모 정도로 설계하는 것이 합리적이다. 본 연구에서 제시한 빗물 재이용을 고려한 빗물이용시설의 계획은 빗물이용시설을 보다 합리적으로 계획하는데 도움을 줄 수 있을 것으로 판단된다.

• Proceedings of the Korean Information Science Society Conference
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• 2001.04b
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• pp.199-201
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• 2001

데이터베이스 시스템은 웹의 발달과 함께 웹 데이터베이스라는 새로운 단계로 진화하고 있다. 웹 데이터베이스에서는 다양한 데이터 소스의 통합이 가장 큰 이슈로 미디에이터에서 각 래퍼가 가져온 스키마를 통합하는 작업을 수행한다. 미디에이터에서는 이와 같이 데이터 소수의 통합 외에 사용자에게 질의를 각 데이터 소스에 대하여 재작성 하는 기능이 중요하고 이에 대한 다양한 연구가 진행 중이다. 이때 질의를 각 소스가 처리할 수 있는 부질의로 재작성 할 때 필요한 개념이 capability이다. 본 논문에서는 capability를 기반으로 한 질의 시스템에서 사용자에게 제공되는 뷰와 질의에 대해서도 capability를 적용한 사용자 기반 capability 기법을 제안한다. 지금까지 타 연구에서는 소스에 대한 capability만을 고려하여 질의를 재작성 하였지만 본 논문에서는 사용자 기반의 capability를 함께 고려함으로써 사용자 요구사항을 충족시키면서도 비교적 간단한 분석과 매칭 과정에 의해 컴파일 시간 내에 계산이 가능하도록 하는 알고리즘을 제시한다. 또한 네트워크의 문제 등으로 인해 소스 중 일부분이 사용할 수 없는 상황인 경우 소스에 대해 active selection이 가능하도록 하여 대체 질의를 생성할 수 있게 하였다. 간단한 구현과 제시한 기법이 비용을 절감하는 실제적인 방법이며 타 연구와의 비교를 통해 좋은 성능을 가짐을 보인다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.6
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• pp.135-140
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• 2015

The Cyber-Physical Systems (CPS) complexly perform modeling and simulation (M&S) for the various embedded systems. In this case, due to use diverse formatted models, we suggest to apply with the SEDRIS to systematically manage the different formatted data on M&S. The SEDRIS can reduce time and cost with reusing and interoperating environment data developed in the specific domain. To do this, we should input the data transformed the height map for terrain representation in a simulator into raster data of SEDRIS for which interoperate between the existed simulator and the SEDRIS. To solve the problem, we propose the transformation method to transfer the polygon data from RAW file used in terrain representation. With the proposed method, we can provide two advantages. First, it can possibly express the environment data into SEDRIS. Second, we can see the terrain like an image file through a viewer. Therefore, even non-expert easily constructs the terrain environment data.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.6
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• pp.1277-1285
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• 2015

It has been known that the conventional retaining wall system with timber lagging and H pile has several problems such as the irregular gap between H-piles, cutting or adding to standard timber, back fill over first step excavation, and especially break-down accident at the disjoint of wall system. In the practical excavation, these problems may lead to worker's accident and the inefficiency of construction economy. To solve the above problems, a new method using prefabricated retaining wall was proposed and verified. The characteristics of the new method is to replace timber wall as free-sliding steel-lagging and connector. To check its verification and application, laboratory tests such as bending strength, tensile strength, and fatigue strength were carried out. Also, a pilot test in the field and numerical simulations under various ground conditions were performed. From the researches, it is found that the prefabricated retaining wall plate can be superior to the conventional timber lagging plate in the strength. It is also found that the proposed methods can be effective in the reuse of retaining wall plate and safe in the disjoint of wall system. Finally, it is desired that the proposed method will be effective in the reduction of the imported timbers and helpful in the safety of retaining wall construction.