• KIPS Transactions on Software and Data Engineering
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• v.2 no.11
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• pp.765-778
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• 2013

This paper proposes a test case generation method for Stateflow model using the extended RRT method. The RRT method which has been popularly used for planning paths for complex systems also shows a good performance for test case generation. However, it does not consider the test coverage which is important for test case generation. The proposed extension method hires the concept of test goal achievement to increase test coverage and drives RRT extension in the direction that increases the goal achievement. Considering the concept, a RRT distance metric, random node generation method and modified RRT extension algorithm are proposed. The effectiveness of proposed algorithm is compared with that of the typical RRT algorithm through the experiment using the practical automotive ECUs.

• Proceedings of the Korean Information Science Society Conference
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• 2012.06b
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• pp.193-195
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• 2012

소프트웨어 시스템의 신뢰성과 안정성을 보장하기 위해서는 시스템에 내재된 결함을 가능한 많이 줄이는 것이 중요하다. 이는 테스팅을 통해 수행할 수 있으며, 상태 다이어그램을 기반으로 한 테스팅 기법들이 많이 연구되고 있다. 이러한 연구들은 상태와 전이의 경로 커버리지에 초점을 두고, 메시지 시퀀스에 따른 테스트를 고려한다. 하지만 메시지 시퀀스에 따른 테스트 케이스는 모두 정상적인 환경의 테스트 데이터를 반영하고, 그에 따라 무효한 테스트에 취약성을 보인다. 따라서 본 논문에서는 부가적인 산출물을 최소화하고, 시스템의 예외처리를 강화하기 위해 가상의 비정상 전이와 상태를 추가하여 상태 다이어그램으로부터 무효한 테스트 케이스를 도출하는 방법을 제안한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2000.10b
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• pp.1207-1210
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• 2000

프로토콜을 설계하고 이를 구현하면 IUT가 프로토콜 규격과 일치하는지를 검증하는 적합성 시험을 수행한다. 기존의 시험열 생성 방법은 오일러 경로에 의한 방법을 사용하였으나 이 방법은 전체 경로를 다 포함하지 못한다는 단점이 있다. 이 단점을 개선하여 TPT(Transition Possibility Tree)를 생성하여 확장된 테스트 커버리지를 갖는 서브투어 생성방법이 제안되었다. 이 논문에서 기존에 제안된 TPT 서브투어 생성 방법에서 시험열의 갯수가 많아진다는 단점을 보안하여 TPT 서브투어 생성 방법에서의 효과적인 시험열 선택 방법을 제안하였다. 제안 방법에 의해서 생성된 시험열도 완전한 시험 목적에 부합하지 않는다는 단점은 있으나 시험자가 선택해야 하는 시험열의 양을 최소화하는 데 그 의미가 있다.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.30 no.5
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• pp.847-857
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• 2020

As IoT equipment is commercialized, Bluetooth or wireless networks will be built into general living devices such as IP cameras, door locks, cars and TVs. Security for IoT equipment is becoming more important because IoT equipment shares a lot of information through the network and collects personal information and operates the system. In addition, web-based attacks and application attacks currently account for a significant portion of cyber threats, and security experts are analyzing the vulnerabilities of cyber attacks through manual analysis to secure them. However, since it is virtually impossible to analyze vulnerabilities with only manual analysis, researchers studying system security are currently working on automated vulnerability detection systems, and Firm-AFL, published recently in USENIX, proposed a system by conducting a study on fuzzing processing speed and efficiency using a coverage-based fuzzer. However, the existing tools were focused on the fuzzing processing speed of the firmware, and as a result, they did not find any vulnerability in various paths. In this paper, we propose IoTFirmFuzz, which finds more paths, resolves constraints, and discovers more crashes by strengthening the mutation process to find vulnerabilities in various paths not found in existing tools.

• Journal of the Korean Society for Railway
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• v.16 no.6
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• pp.460-465
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• 2013

Radio propagation in a high-speed railway is affected by ground reflective waves that are due to irregular reflection by the railway track, which consists of rails, sleepers, and gravel. This paper provides a train radio propagation model that simulates an irregular track reflective wave as a random variable. A simulation study using the train radio propagation model shows that the path loss exponent is around 3.0, indicating a reduced path loss compared to the value of 4.0 in the general mobile radio environment. Regressive analysis of the received signal strength indicators measured in the Gyeongbu high-speed railway showed the results identical to those of the simulation. These results confirm the train radio propagation model and can be applied to the coverage estimation and the design of a train radio network.

• Journal of Korea Society of Industrial Information Systems
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• v.17 no.7
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• pp.9-16
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• 2012

In order to extend cell coverage and to cope with shadow areas, a relay-assisted wireless communications system has been widely studied. In this paper, we propose new equalization method for single carrier (SC) frequency domain equalizer (FDE) in amplify-and-forward (AF) relaying multi-path networks to improve the performance at shadow areas. The performance of SC-FDE system in 3-slot based multi-path networks can be improved considerably with the diversity gain which we obtain by equalizing the combined signal from relays by means of the minimum mean square error (MMSE) criteria. We find the weighting coefficients of maximum ratio combining (MRC) and the tap coefficients of MMSE equalizer for SC-FDE in AF relaying multi-path networks. Simulation results show that the proposed system considerably outperforms the conventional SC-FDE system.

• The KIPS Transactions:PartC
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• v.14C no.2
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• pp.139-146
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• 2007

Mobile Sensor Network(MSN) is actively studied due to the advent of mobile sensors such as Robomote and Robotic Sensor Agents(RSAs), However, existing studies on MSN have mainly focused on coverage hole problem which occurs in Stationary Sensor Network(SSN). To address coverage hole problem, these studies make mobile sensors move temporarily so that they do not make the best use of the mobility of mobile sensors, Thus, a mechanism utilizing the continuous movement of mobile sensors is proposed to improve the network coverage performance. However, this mechanism is presently immature and does not explain how to make routing path and send data from mobile sensors to a sink node, Therefore, to efficiently make routing path and send data from mobile sensors to a sink node, we propose a communication protocol for mobile sensor network where mobile sensors continuously move. The proposed protocol deploys not only mobile sensors but also stationary sensors which send sensing data to a sink node instead of mobile sensors. Simulation results show that the proposed protocol improves the performance in terms of network coverage and traffic overhead, compared to conventional SSN protocols.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.2A
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• pp.91-99
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• 2011

Several repeater systems are used to enhance the cell coverage to location such as shadow and rural areas in mobile systems. But the general RF repeater solutions are not suitable for high power outdoor environment because it has the weakness such as self oscillation problem With adoption of a adaptive digital filter technology, feedback interference cancellation repeater prevents oscillation by detecting and canceling the unwanted feedback signal between transmission and receiver antenna. In this paper, dual NLMS based interference cancellation method is proposed and the step size adaptation can be implemented by the estimation of the feedback channel Doppler frequency characteristics. The performance of the proposed algorithm is quantified via analysis and simulation for the static and multipath fading feedback channels.

• Journal of Navigation and Port Research
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• v.26 no.1
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• pp.15-21
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• 2002

Re Ministry of Maritime Affairs and Fisheries in Korea completed the installation of 8 maritime DGPS station mfd is to going install 3 additional Maritime DGPS station for the enhancement of dual coverage in Korean coasts until Oct. 2002. Moreover, Korean government decided to provide the NDGPS service over the whole Korean inland area, which will be schedule to complete until June. 2004. On this paper to evaluate the propagation characteristics of using maritime DGPS site as un element of NDGPS ann to evaluate the required number of additional NDGPS sites, the propagation characteristics of the radio waves of 300kHz bands on sea and land nth are studied With the result of study, the conceptional design of Korean NDGPS System is proposed, which consists of 5 NDGPS sites with modified antenna and tかee coverage monitoring sites.

• Journal of the Korean Society of Clothing and Textiles
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• v.34 no.2
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• pp.189-199
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• 2010

This study develops a coverall design for the body shape and movement of infants. This research analyzed these processes: 1. The current coverall styles preferred for infants. 2. The appropriate products for the real size, body shape, movement, and fit of infants. 3. The observations of the 6 months to 9 months movement and development of infants. 4. The design and creation of a new coverall base in this study, and to check the suitable test the developed coverall design for the infant. The result of this study are: A coverall for infants that lie or crawl on the floor must avoid opening in the center front and a gore has to be added at the crotch of the pants for the better movement of infants. These ways provide infants a neat appearance and easy movement. The test of developed designs shows that the developed coverall design covers the size gap of the trunk loop according to the growth of the infant and the movement of the legs; in addition it provides a positive aesthetic effect. The waistline in the developed coverall (a waistline that should exist lower than the body waistline of the infant) can reduce seam stress because the pressure of the seam line can be absorbed in a dipper. It is one of the suitable design points for infants lying prone all day long in this study.