• 디지털산업정보학회논문지
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• 제13권3호
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• pp.43-51
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• 2017

MANET consists of only wireless nodes having limited processing capability. It processes routing and data transmission through cooperation among each other. And it is exposed to many attack threats due to the dynamic topology by movement of nodes and multi-hop communication. Therefore, the reliability of transmitted data between nodes must be improved and security of integrity must be high. In this paper, we propose a method to increase the reliability of transmitted data by providing a secure cryptography protocol. The proposed method used a hierarchical structure to provide smooth cryptographic services. The cluster authentication node issues the cluster authentication key pair and unique key to the nodes. The nodes performs the encryption through two steps of encryption using cluster public key and block encryption using unique key. Because of this, the robustness against data forgery attacks was heightened. The superior performance of the proposed method can be confirmed through comparative experiment with the existing security routing method.

• 대한전기학회논문지:전력기술부문A
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• 제48권7호
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• pp.855-862
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• 1999

A high speed digital distance relaying algorithm based on a least square error method is proposed. To obtain stable phasor values very quickly, first, a lowpass filter which has very short transient period and no overshoot is presented. Secondly, the least square error method having the data window of 3 samples is used by applying a FIR filter which removes the DC-offset component in current relaying signals. Test results show that the proposed distance relaying algorithm detects most of internal faults within a half cycle after faults in a 154[kV] overhead transmission line system.

• ETRI Journal
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• 제38권5호
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• pp.868-878
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• 2016

A multi-screen environment provides a new opportunity for digital signage applications, where various irregularly shaped screens are employed as an effective means for advertisements and information. A formation method applicable to numerous irregularly shaped screens is proposed to provide a new perspective on digital signage applications. The crucial part of the proposed method comes from the geometric sensing of each screen and the formation of a virtual screen where geometrically aligned content extraction and encoding are employed for content transmission to each screen. In addition, a software-based synchronization method for the proposed system is proposed to address the frame-level synchronization between screens. The experimental results of the proposed method show an improved performance of the frame-level synchronization, where the inconsistency between frames is not identified.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제18권6호
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• pp.1619-1637
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• 2024

In today's highly digitized landscape, securing digital communication is paramount due to threats like hacking, unauthorized data access, and network policy violations. The response to these challenges has been the development of cryptography applications, though many existing techniques face issues of complexity, efficiency, and limitations. Notably, sophisticated intruders can easily discern encrypted data during transmission, casting doubt on overall security. In contrast to encryption, steganography offers the unique advantage of concealing data without easy detection, although it, too, grapples with challenges. The primary hurdles in image steganography revolve around the quality and payload capacity of the cover image, which are persistently compromised. This article introduces a pioneering approach that integrates image steganography and encryption, presenting the BitPatternStego method. This novel technique addresses prevalent issues in image steganography, such as stego-image quality and payload, by concealing secret data within image pixels with identical bit patterns as their characters. Consequently, concerns regarding the quality and payload capacity of steganographic images become obsolete. Moreover, the BitPatternStego method boasts the capability to generate millions of keys for the same secret message, offering a robust and versatile solution to the evolving landscape of digital security challenges.

• 한국CDE학회논문집
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• 제16권4호
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• pp.260-267
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• 2011

Nowadays, automobile manufacturers are faced with increasing global competition which is required low cost as well as high quality. To reduce shipping and handling cost and delivery time, lots of automobile manufactures tried to build their new factory in the neighborhood of market. Simultaneously, many factories are under construction in developing countries to make efficient use of low-wage workers. However, because systems are installed in developing countries as the same type of domestic facilities, systems have lots of problems such as high installation cost and inefficient use of manpower. To find core problems and generate optimal solution of these problems, thinking process of TOC(Theory Of Constrains) is used. In case of transmission gear machining system, semi-auto system is proposed as the best solution to increase manpower efficiency and system utilization. Semi-auto system consists of automatic machining process and manual transporting process. The system layout is generated based on semi-auto process concept. And, 3D simulation method using QUEST is used to verify production volume of generated system.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제5권11호
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• pp.2068-2086
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• 2011

Based on the quincunx sub-sampling grid, the New Interleaved Hierarchical INTerpolation (NIHINT) method is recognized as a superior pyramid data structure for the lossless and progressive coding of natural images. In this paper, we propose a new image interpolation algorithm, Edge Adaptive Hierarchical INTerpolation (EAHINT), for a further reduction in the entropy of interpolation errors. We compute the local variance of the causal context to model the strength of a local edge around a target pixel and then apply three statistical decision rules to classify the local edge into a strong edge, a weak edge, or a medium edge. According to these local edge types, we apply an interpolation method to the target pixel using a one-directional interpolator for a strong edge, a multi-directional adaptive weighting interpolator for a medium edge, or a non-directional static weighting linear interpolator for a weak edge. Experimental results show that the proposed algorithm achieves a better compression bit rate than the NIHINT method for lossless image coding. It is shown that the compression bit rate is much better for images that are rich in directional edges and textures. Our algorithm also shows better rate-distortion performance and visual quality for progressive image transmission.

• 한국음향학회지
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• 제21권4호
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• pp.394-400
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• 2002

디지털 음성 통신에서 송신하는 음성 패킷의 전송 에러율을 알면 송신 채널 상황에 적합한 압축 동작을 통하여 전체 통신의 품질을 향상시킬 수 있다. 그러나 현재의 이동통신과 인터넷 통신에서는 음성 패킷의 전송 에러정보를 알려주는 프로토콜이 지원되지 않는다. 본 논문에서는 이를 해결하기 위하여 채널의 전송 에러 정보를 음성 패킷에 삽입하여 실시간으로 전달하는 방법을 제안한다. 제안하는 채널 에러 정보 삽입 방법은 ACELP (algebraic code-excited linear predictin) 코드벡터의 펄스 위치의 상관 관계를 이용하며, 이를 통하여 추가정보 삽입에 의한 음질 저하를 막고 오인식율을 줄일 수 있다. 다양한 음성 데이터를 이용하여 제안한 방법의 성능을 측정하였으며 음질의 저하가 거의 발생하지 않고 정보의 검출 능력과 오인식율에서 만족할 만한 성능을 가지는 것을 확인하였다.

• 한국군사과학기술학회지
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• 제13권4호
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• pp.577-585
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• 2010

The Military Tactical Communication technology for effective network-centric warfare is developing. Targeting broadband wireless transmission, core technology for connection, and Transmission technology that secure survivability under High-speed Movement environment. On the one hand, Tactical data communication system that reflects military characteristic is developing on the base of Legacy communication equipment which is used in the field. Because almost every military units in the field have used voice to communicate which lower efficiency of operation, they have made effort to Substitute voice communication which delays military Operation Tempo to digital communication. The Communications environment of troops in Forward edge of battle field area is very poor. Especially in terms of limited frequency allocation and bandwidth. Therefore, improving the efficiency of frequency is essential for Military Tactical Communication. This paper is about The Data Compression Method for increase of Efficiency in Tactical Data Communication over Legacy Radios which are UHF, VHF, HF Radio. I proposed and proved the most efficient Data Compression Method that reflects military characteristic, after analyzing the experimentation, which simulate CAS(Close Air Support mission) data transmission between Pilot and TACP.

• 대한전자공학회논문지SD
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• 제46권8호
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• pp.12-17
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• 2009

마이크로프로세서를 사용하여 디지털 방식에 의해 온도보상을 하는 버스트 모드 광송신기를 구현하였다. 기존 실시간으로 신호를 처리하는 아날로그 방식의 온도보상 방법에 비하여, 본 연구에서 구현한 디지털 방식의 온도보상은 신호를 샘플링 처리함으로써 고속 버스트 모드 광신호를 효과적으로 처리할 수 있다. 온도보상을 위한 디지털 자동전력조절 방식은 데이터 전송속도에 영향을 받지 않을 뿐만 아니라, 아날로그 방식에 비해 보다 정확하고 효율적이므로 Gb/s 이상의 고속 버스트 광신호 처리에 유용하게 사용될 수 있다.

• 디지털융복합연구
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• 제11권12호
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• pp.423-430
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• 2013

인터넷을 이용한 전자상거래 및 금융 분야가 활성화되어 사용자와 서비스 제공자들 간의 상호 인증이 매우 중요해졌다. ID와 패스워드 기반의 인증은 보안성이 낮기 때문에 일회용 패스워드 인증방식이 많이 사용되고 있다. 기존의 일회용 패스워드 인증방식인 S/Key 인증방식은 평문 전송 외에 여러 문제점이 있고, 김홍기 등의 방식은 세션 키의 생성 및 분배 방법에 관한 제시가 없다는 문제점이 있다. 본 논문에서는 이러한 문제점을 해결하기 위한 프로토콜을 제안하였다.