• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.7
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• pp.3095-3111
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• 2018

Spectrum sensing (SS) is one of the fundamental tasks for cognitive radio. In SS, decisions can be made via comparing the test statistics with a threshold. Conventional adaptive algorithms for SS usually adjust their thresholds according to the radio environment. This paper concentrates on the issue of adaptive SS whose threshold is adjusted based on the Markovian behavior of primary user (PU). Moreover, Bayesian cost is adopted as the performance metric to achieve a trade-off between false alarm and missed detection probabilities. Two novel adaptive algorithms, including Markov Bayesian energy detection (MBED) algorithm and IMBED (improved MBED) algorithm, are proposed. Both algorithms model the behavior of PU as a two-state Markov process, with which their thresholds are adaptively adjusted according to the detection results at previous slots. Compared with the existing Bayesian energy detection (BED) algorithm, MBED algorithm can achieve lower Bayesian cost, especially in high signal-to-noise ratio (SNR) regime. Furthermore, it has the advantage of low computational complexity. IMBED algorithm is proposed to alleviate the side effects of detection errors at previous slots. It can reduce Bayesian cost more significantly and in a wider SNR region. Simulation results are provided to illustrate the effectiveness and efficiencies of both algorithms.

• Fire Science and Engineering
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• v.27 no.6
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• pp.83-88
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• 2013

Catastrophic disasters are sprouting out recently, i.e., the radiation leaks and the hydrofluoric acid gas leaks, etc. The restoration work for these kinds of disasters is very harmful and dangerous for human beings to handle themselves, thus allowing manless robots to fly the reconnaissance planes over to the disaster stricken areas and do the necessary work instead. For this endeavor and purpose, we created and tested an intelligent robot that can inspect those areas, using Mbed (ARM processor) technology temperature sensors and gas sensors aided by CAM (Computer-Aided Manufacturing) cameras. Also, HTTP Server, PC, androids and their combined efforts allow their remote controlled operation from far away with timing control. These intelligent robots can be on duty for 24 hours, minimizing the accidents and crimes and what not, and can respond more quickly when these misfortunes actually happen. We can anticipate the economic effects as well, derived from the reduced needs for hiring human resources.

• Review of KIISC
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• v.30 no.3
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• pp.11-16
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• 2020

기술의 발전으로 이론으로만 존재하던 양자 알고리즘의 실현 가능성이 보이면서 기존 암호체계의 위협이 발생할 것으로 예측하고 있다. 미국 국립표준기술연구소에서는 양자컴퓨터 환경에서도 안전한 새로운 공개키 기반의 암호체계가 필요하다는 것을 강조하였고 양자내성암호 표준을 위한 공모전을 개최하였다. 암호는 네트워크 통신에서 중요한 역할을 하고 있고 네트워크 보안 프로토콜로 TLS가 많이 사용된다. 본 논문에서는 IoT와 같은 경량 환경에 적합한 TLS 라이브러리인 mbedTLS 상에서의 격자기반 양자내성 키 교환 알고리즘을 구현하고 성능을 평가하여 양자내성암호의 사용 가능성에 대해 제시한다.

• Journal of Institute of Control, Robotics and Systems
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• v.21 no.11
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• pp.1038-1043
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• 2015

When the study on the relationship between the Head-of-Bed (HOB) angle and ventilator-associated pneumonia is performed, the fact that the HOB angle can only be measured intermittently imposes a significant limitation on the study. Therefore, there has been demand for the development of a device that can measure the HOB angle continuously. In this paper, we propose the rapid prototyping of an HOB measurement system using open-source hardware and software. The proposed system helps to maintain the HOB angle at a particular angle by displaying the angle and helps the medical study of pneumonia patients by enabling continuous data acquisition. Firstly, we eliminate the process of making an MCU board by utilizing an open-source hardware mbed LPC1768. Secondly, we reduce the software development time by using libraries and hence enabling the easy use of peripherals. Thirdly, for rapid prototyping, we build the enclosure of the proposed system using a 3D printer. The proposed system can be attached and detached to and from a bed. Therefore, we can attach it to the bed of a patient for whom measurement of the HOB angle is necessary. Finally, we check the measurement performance and the validity of the proposed system through an experiment utilizing an incremental encoder.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.30 no.6
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• pp.1079-1085
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• 2020

Fuzzing is used to find vulnerabilities for a library. Because library fuzzing only tests the implemented functions, in order to achieve higher code coverage, additional functions that are not implemented should be implemented. However, if a function is added without regard to the calling relationship of the functions in the library, a problem may arise that the function that has already been tested is added. We propose a novel method to improve the code coverage of library fuzzing. First, we analyze the function call graph of the library to efficiently add the functions for library fuzzing, and additionally implement a library function that has not been implemented. Then, we apply a hybrid fuzzing to explore for branches with complex constraints. As a result of our experiment, we observe that the proposed method is effective in terms of increasing code coverage on OpenSSL, mbedTLS, and Crypto++.

• Journal of Internet of Things and Convergence
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• v.8 no.1
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• pp.79-85
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• 2022

Internet of Things (IoT) connects devices with various platforms, computing power, and functions. Due to the diversity of networks and the ubiquity of IoT devices, demands for security and privacy are increasing. Therefore, cryptographic mechanisms must be strong enough to meet these increased requirements, while at the same time effective enough to be implemented in devices with long-range specifications. In this paper, we present the performance and memory limitations of modern cryptographic primitives and schemes for different types of devices that can be used in IoT. In addition, detailed performance evaluation of the performance of the most commonly used encryption algorithms in low-spec devices frequently used in IoT networks is performed. To provide data protection, the binary ring uses encryption asymmetric fully homomorphic encryption and symmetric encryption AES 128-bit. As a result of the experiment, it can be seen that the IoT device had sufficient performance to implement a symmetric encryption, but the performance deteriorated in the asymmetric encryption implementation.

• Review of KIISC
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• v.28 no.5
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• pp.26-30
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• 2018

사물인터넷 서비스는 다양한 기능과 성능을 갖는 디바이스와 게이트웨이, 플랫폼, 서비스가 서로 상호 연동/통신함으로써 실현된다. 해당 서비스의 안전성 및 신뢰성을 보장하기 위해선 서비스 각 구성 요소에 적절한 보안 기술이 필요하다. 서비스 및 API 수준에서는 OpenID-connect, OAuth2, SAML, XACML과 같은 인증/인가, 접근 제어 기법이 필요하며, 플랫폼 및 프로토콜 수준에서는 MQTT, CoAP, HTTPS, RSPF 프로토콜 및 보안 절차가 필요하다. 한편, 이들 보안 기술은 공통적으로 TLS/DTLS 보안 프로토콜을 사용한다는 특성을 가진다. 이에, 본 논문에서는 사물인터넷의 디바이스, 게이트웨이, 플랫폼에서 손쉽게 사용될 수 있도록 TLS/DTLS 보안 칩 개발 사례를 소개하고 이를 TLS 오픈 소프트웨어 스택인 mbedTLS와의 연동 사례를 소개함으로써 사물인터넷 구성 요소에 공통적으로 활용 가능한 보안 기술 구현 사례를 살펴본다.