• The Journal of Korean Institute of Communications and Information Sciences
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• v.37B no.9
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• pp.741-749
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• 2012

Ad Hoc Self-Organizing TDMA (ASO-TDMA) has been proposed as a specification to support the multi-hop data communication service for ships over VHF band. It allows for organizing a multi-hop ad-hoc network in a distributed manner by sharing the radio resources among the ships navigating along the route. In this paper, Markov chain analysis is given to provide the average throughput performance for ASO-TDMA protocol Furthermore, the analytical results are verified with computer simulation, which shows that there exists the optimal transmission rate to maximize the average throughput as the subframe size and the number of ships are varying in each hop region.

• Proceedings of the KIEE Conference
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• 2005.07d
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• pp.3037-3039
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• 2005

The AIS(Automatic Identification System) transmits the position of ships and other information to prevent accidents which could occur in the sea. It has to be developed SOTDMA(Self-Organized Time Division Multiple Access) Algorithm which is important on wireless communication method for the AIS because It is based on ITU(International Telecommunication Union) M.1371-1 of the international standard therefore, we need to develop a performance evaluation simulator efficiently to develop and analyze SOTDMA Algorithm. this paper shows the method of designing it. Real ships access The VHF maritime mobile band but in this performance evaluation simulator several ship objects access the shared memory. Real ships are designed as the object and the wireless communication channel is designed as the shared memory. The ships apply for real virtual data which got from assistance hardware and The SOTDMA Algorithm driving state verifies the performance evaluation simulator by IEC(International Electrotechnical commission) 61993-2. After verifying results the performance evaluation simulator is correctly satisfied with IEC 61993-2. So we expect that it helps not only the AIS technology developed but also verify new SOTDMA Algorithm

• Proceedings of the KIEE Conference
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• 2005.10b
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• pp.478-480
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• 2005

The AIS(Automatic Identification System) transmits the position of ships and other information to prevent accidents which could occur in the sea. It has to be developed SOTDMA(Self-Organized Time Division Multiple Access) Algorithm which is important on wireless communication method for the AIS because It is based on ITU(International Telecommunication Union) M.1371-1 of the international standard therefore, we need to develop a performance evaluation simulator efficiently to develop and analyze SOTDMA Algorithm. This paper shows the method of designing it. Real ships access The VHF maritime mobile band but in this performance evaluation simulator several ship objects access the shared memory. Real ships are designed as the object and the wireless communication channel is designed as the shared memory. The ships apply for real virtual data which got from assistance hardware and The SOTDMA Algorithm driving state verifies the performance evaluation simulator by IEC(International Electrotechnical commission) 61993-2. After verifying results the performance evaluation simulator is correctly satisfied with IEC 61993-2. So we expect that it helps not only the AIS technology developed but also verify new SOTDMA Algorithm.

• Proceedings of the KIEE Conference
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• 2004.07d
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• pp.2432-2434
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• 2004

In this paper, we present a novel approach for the structure of Fuzzy Neural Network(FNN) based on wavelet function and apply this network structure to the solution of the tracking problem for mobile robots. Generally, the wavelet fuzzy model(WFM) has the advantage of the wavelet transform by constituting fuzzy basis function(FBF) and the conclusion part to equalize the linear combination of FBF with the linear combination of wavelet functions. However, it is very difficult to identify the fuzzy rules and to tune the membership functions of the fuzzy reasoning mechanism. Neural networks, on the other hand, utilize their learning capability for automatic identification and tuning. Therefore, we design a wavelet based FNN structure(WFNN) that merges these advantages of neural network, fuzzy model and wavelet. To verify the efficiency of our network structure, we evaluate the tracking performance for mobile robot and compare it with those of the FNN and the WFM.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.10a
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• pp.159-162
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• 2007

최근 통신 기술의 발달로 육상이동통신 기술을 해상 및 항공에 확대하려는 시도가 꾸준히 진행되고 있다. 해상 및 항공 통신은 인명 안전을 위한 통신으로 국제 기구에 의해서 최우선적인 보호를 받아 왔다. 그러나 통신 기술의 급속한 발전으로 해상 및 항공 통신망은 기존 음성 위주의 통신망에서 멀티미디어를 처리할 수 있는 디지틀망으로의 전환이 시급히 필요하게 되었다. 해상통신의 경우에는 디지틀 통신 방식을 이용하는 DSC(Digital Selective Calling), AIS(Automatic Identification System) 등을 이미 도입해서 운용 중에 있으며 다른 시스템으로의 확대가 진행 중에 있다. SOLAS 선박뿐 만 아니라 비 SOLAS(Safety Of Life At Sea) 선박들도 디지틀 통신을 활용하면 항행 안전에 매우 도움이 될 것이다. 최근에 ITU-R에서는 VHF(Very High Frequency) 대역에서 데이터 및 이메일 등을 송수신하기 위한 데이터 통신시스템 기술에 대한 논의가 진행 중에 있다. 본고에서는 이 VHF대역 데이터시스템에 대한 기술적 특성을 분석하고 향후 해상통신에서의 디지틀 기술이 도입된 후 전개될 해상통신망에 대해서 기술하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.3
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• pp.576-599
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• 2013

Protocol reverse engineering is useful for many security applications, including intelligent fuzzing, intrusion detection and fingerprint generation. Since manual reverse engineering is a time-consuming and tedious process, a number of automatic techniques have been proposed. However, the accuracy of these techniques is limited due to the complexity of binary instructions, and the derived formats have missed constraints that are critical for security applications. In this paper, we propose a new approach for protocol format extraction. Our approach reasons about only the evaluation behavior of a program on the input message from concolic execution, and enables field identification and constraint inference with high accuracy. Moreover, it performs binary analysis with low complexity by reducing modern instruction sets to BIL, a small, well-specified and architecture-independent language. We have implemented our approach into a system called Icefex and evaluated it over real-world implementations of DNS, eDonkey, FTP, HTTP and McAfee ePO protocols. Experimental results show that our approach is more accurate and effective at extracting protocol formats than other approaches.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.5 no.10
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• pp.1783-1798
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• 2011

Recently, a cryptographic construct, called fuzzy vault, has been proposed for crypto-biometric systems, and some implementations for fingerprint have been reported to protect the stored fingerprint template by hiding the fingerprint features. In this paper, we implement the fuzzy fingerprint vault, combining fingerprint verification and fuzzy vault scheme to protect fingerprint templates. To implement the fuzzy fingerprint vault as a complete system, we have to consider several practical issues such as automatic fingerprint alignment, verification accuracy, execution time, error correcting code, etc. In addition, to protect the fuzzy fingerprint vault from the correlation attack, we propose an approach to insert chaffs in a structured way such that distinguishing the fingerprint minutiae and the chaff points obtained from two applications is computationally hard. Based on the experimental results, we confirm that the proposed approach provides higher security than inserting chaffs randomly without a significant degradation of the verification accuracy, and our implementation can be used for real applications.

• Journal of Sensor Science and Technology
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• v.14 no.4
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• pp.278-285
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• 2005

This paper describes techniques of camera calibration and artificial landmarks detection for the automatic charging of a mobile robot, equipped with a fish-eye camera in the direction of its operation for movement or surveillance purposes. For its identification from the surrounding environments, three landmarks employed with infrared LEDs, were installed at the charging station. When the robot reaches a certain point, a signal is sent to the LEDs for activation, which allows the robot to easily detect the landmarks using its vision camera. To eliminate the effects of the outside light interference during the process, a difference image was generated by comparing the two images taken when the LEDs are on and off respectively. A fish-eye lens was used for the vision camera of the robot but the wide-angle lens resulted in a significant image distortion. The radial lens distortion was corrected after linear perspective projection transformation based on the pin-hole model. In the experiment, the designed system showed sensing accuracy of ${\pm}10$ mm in position and ${\pm}1^{\circ}$ in orientation at the distance of 550 mm.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.10
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• pp.2235-2241
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• 2009

RFID and USN are major technology in Ubiquitous. RFID is an automatic identification method, relying on storing and remotely retrieving data using devices called RFID tags or transponders through RFID reader. USN is wireless sense network and monitoring environment conditions that is temperature, noise, pressure, oscillation. In this paper, we propose wireless sensor network system that is monitoring to optimize environment conditions.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.05a
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• pp.237-240
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• 2010

AIS(Automatic Identification System)는 선박과 육상 및 선박 상호간에 선박의 항행관련 정보를 상호 교환함으로써 안전항해를 제고하기 위하여 도입된 무선설비로서 그 활용도가 매우 높아지고 있으며 AIS 탑재 선박도 증가하고 있다. 그러나 AIS에서 사용하고 있는 초단파의 전파 특성으로 인하여 비교적 근거리 통신만 가능하고 장거리 선박추적 관리를 위한 용도로 활용하는 데는 어려움이 있었다. 이러한 통신권의 한계를 극복하기 위한 방안으로 저궤도 위성을 사용하는 위성 AIS의 도입에 대한 연구가 주요 선진국을 중심으로 추진되고 있으며, 성능을 제고하기 위한 기술 기준 연구도 진행되고 있다. 본 연구에서는 저궤도 위성을 사용한 AIS의 문제점인 메시지 수신확률을 분석하기 위하여 현재 사용 중인 지상파 AIS의 특성 및 저궤도 위성 AIS의 문제점을 분석하고 메시지 수신확률에 대한 시뮬레이션을 수행하여 그 결과를 분석하였다. 분석결과 위성 AIS는 지상파 AIS에 비하여 통신권이 크게 확대되는 반면 채널 용량의 한계 및 채널간 간섭으로 인하여 AIS 메시지 충돌이 심하게 발생하고 메시지 수신 확률이 매우 낮음을 알 수 있었다. 따라서 현재의 지상파 AIS 표준을 적용한 위성 AIS의 실시간 정보 교환은 사실상 불가능하며 위성 AIS의 메시지 수신 확률을 제고하기 위해서는 위성 AIS를 위한 별도의 표준을 제정할 필요가 있음을 알 수 있다.