• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.12 no.3
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• pp.1-10
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• 2013

Most of the current traffic signal controller use load switches to transmit high voltage power to the signal lamps. The direct transmission of high voltage power may cause a lot of problems like leakages of electric power, obstructions of pedestrian, environmental disfigurements. To overcome these problems, the development of digital type signal controller has been trying in the various methods. Digital communication between a master controller and signal lamps is the most important part to improve control performance in the digital type controller. A communication system for the digital signal controller was developed in this study. The system bases on CAN specification, includes ID structure for most peripheral devices like loops, signal lamps, push buttons, police switches. The operability of this system verified with a software based CAN simulation tool.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.4
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• pp.744-752
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• 2017

ECQV implicit certificate reconstructs the public key from the certificate without validation of the signature unlike the explicit certificate. Like this, the certificate and the public key is implicitly validated when a public key is reconstructed from a certificate. Hence, ECQV implicit certificate is shorter than the explicit certificate due to be only comprised of the public key reconstruction data instead of the signature and the public key, and faster to reconstruct the public key from the certificate than validating the signature. Furthermore, ECQV is well suited for environments and application that resources such as memory and bandwidth are limited because it is shorter the key length, and faster the performance than other cipher cryptography due to be run on ECC. In this paper, we describe prerequisites of ECQV specified in the SECG SEC 4 and issuance of an implicit certificate, reconstruction of the public key from an implicit certificate. Also we designed and implemented ECQV, and measured the performance of it.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.12C
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• pp.1165-1172
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• 2006

The rapid progress of the software has enabled individuals to copy and remark digital contents, which was only done by professionals. As a solution for the problems, contents producer needs to have certification and inspection of its contents and hold the proprietary right. A fragile watermarking method is able to detect the distortion and damage of watermarked image, but the watermark is also fragile on standardized image compression. That is the problem of fragile watermarking technique. We propose semi-fragile watermarking technique that is robust in the image processing such as JPEG compression used on computer, but it is fragile on the addition of noise and other attacks. In the proposed method, we can generate the watermarks of an image from the relationship between two block coefficients, also the generated watermark is inserted into insensible part of HVS(Human Visual System) after processing DCT(Discrete Cosine Transform) and using quantization. As a result, on the spatial domain, high detection of distortion has been possible even in slight changes, and could detect the corrupted blocks on image. Therefore, it is simple to judge the pixels at which some location has been changed in the space.

• Current Industrial and Technological Trends in Aerospace
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• v.5 no.2
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• pp.33-42
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• 2007

위성체 총조립 및 시험(AIT ; Assembly, Integration & Test)을 위한 전기지상지원장비(EGSE ; Electrical Ground Support Equipment)와 위성 임무 준비 및 운용을 위한 관제시스템(MCS ; Mission Control System)의 공동 개발은 미국과 유럽의 위성사업 기관 및 업체에서 지금까지 많은 연구가 되어 왔다. 비록 두 시스템이 다른 목적으로 사용되고 있지만 기술적으로 유사한 기능을 갖는 시스템으로서 많은 공통점과 호환 가능성을 갖고 있다. 두 시스템의 공동 개발은 시스템 개발과 위성 운용 교육 및 준비에 필요한 비용 절감뿐만 아니라 AIT 단계에서 위성운용단계로의 자연스러운 전환이 가능하다. 이는 AIT 단계에서 공통지상시스템 하드웨어 및 운영시스템, 시험/운용 절차서, 위성 데이터베이스의 사전 검증이 이루어지기 때문이다. 또한 위성 운용 요원의 AIT 참여를 통해 공통지상시스템 운용 훈련과 위성 관제 지식 습득이 자연스럽게 이루어 질 수 있다. 이로서 사업 일정과 개발 위험도를 최소화 할 수 있다. 이러한 두 시스템의 공통성과 호환성 및 공통시스템 개발 장점이 있기에 EGSE와 MCS의 공통 기능에 대한 표준화 작업은 1986년 만들어진 COES(Committee for Operations and EGSE Standard)에서 공식적으로 논의되기 시작하여 1994년 CNES와 ESA의 발의로 제정된 ECSS(European Cooperation for Space Standards)를 통해 국제 표준(ISO, CCSDS 등)을 바탕으로 한 지상시스템에 대한 유럽 표준화 작업이 ECSS-E-70 Working Group에서 진행되고 있다. 또한 검증된 지상시스템의 핵심 운영시스템의 소프트웨어 모듈의 재사용을 통해 최근에서 다양한 공통지상시스템이 개발되어 운용되고 있다. 이러한 배경으로 국내에서도 저궤도 위성 개발에서 EGSE 핵심 모듈인 TM/TC 처리 및 Database 관리 모듈을 AIT 단계에서 개발 및 검증 후에 MCS에서의 재사용을 적극적으로 고려하고 있다. 앞으로 국제적인 추세에 따라 AIT 및 지상국간의 기술 및 인력 교류와 핵심모듈 개발을 통한 공통지상시스템 개발의 활발한 전개가 예상된다.

• Aerospace Engineering and Technology
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• v.12 no.2
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• pp.14-23
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• 2013

Fault management design of the satellite describes preparations for failures which can occur during operational phase. Fault management design contains detection and isolation function of anomaly, and also it contains function to maintain the satellite in safe condition until the ground station finds out a cause of failure and takes a countermeasure. Unlike normal operation, safing operation is automatically performed by Power Control and Distribution Unit and Integrated Bus Management Unit which loads Flight Software without intervention of ground station. Since fault management operation is automatical, fault management logic and functionality of relevant hardware should be thoroughly checked during ground test phase, and error which is similar to actual should be carefully applied without damage. Verification test for fault management design is conducted for various subsystems of satellite. In this paper, we show the design process of fault management design verification test for Electrical Power Subsystem and Attitude and Orbit Control Subsystem of Low Earth Orbit satellite flight model and the test results.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.10
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• pp.805-812
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• 2013

The operational flight program(OFP) which has the functions of I/O processing with avionics, flight control logic calculation, fault diagnosis and redundancy mode is embedded in the flight control computer of Smart UAV. The OFP was developed in the environment of PowerPC 755 processor and VxWorks 5.5 real-time operating system. The OFP consists of memory access module, device I/O signal processing module and flight control logic module, and each module was designed to hierarchical structure. Memory access and signal processing modules were verified from bench test, and flight control logic module was verified from hardware-in-the-loop simulation(HILS) test, ground integration test, tethered test and flight test. This paper describes development environment, software structure, verification and management method of the OFP.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.2
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• pp.133-139
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• 2017

Flight control computer of tiltrotor UAV was designed by redundancy system with primary and secondary channels to improve reliability. The redundancy functions consist of channel switching and data recovery. The channel switching function consists of software method by using cross channel data link and hardware method by using watchdog timer. The data recovery is the function to maintain flight condition when the flight control computer is restarted exceptionally in operation. The redundancy system was verified by flight control computer bench test, system integration test and HILS test. This paper describes the redundancy function of tiltrotor UAV flight control computer and test-verification method.

• Journal of the Institute of Convergence Signal Processing
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• v.12 no.4
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• pp.286-290
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• 2011

LBS(Location Based System) is the essential technology of ubiquitous market and utilizes the GNSS(Global Navigation Satellite). GNSS includes GPS of USA, Galileo of Europe Union, QZSS of Japan, Compass of China, and IRNSS of India. Related researches have recently been conducted. Once the satellite is launched, the maintenance such as modification and verification of its function is difficult. Therefore, before the launch of satellites, more precise and concrete verification of performance and operations are needed. In order to do this, hardware testbed may be developed. but software simulators can provide more flexible and cost effective simulation results. These simulators should provide the essential function handling all kinds of error features experienced upon propagation of the GNSS signal. In this paper, we present a design and implementation results of a window-based simulator applying the modeling of various error features for several GNSS.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.5
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• pp.527-536
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• 2018

In this paper, we developed a prototype model accident management SMART-Navigation project. In order to develop a prototype model, we analyzed the status of maritime data exchange standard and procedure. We developed accident management prototype application schema, feature catalog and portrayal catalog in accordance with S-100 standard data model development procedure by collecting requirements related services and referring to related standards. In order to verify accident management prototype model, we test data set based on Gwang-yang Port. The prototype model and test data verified verification software, and it was confirmed that the designated symbol was displayed at the correct position through the S-100 simple viewer.

• Journal of the Korea Society for Simulation
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• v.17 no.4
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• pp.133-142
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• 2008

AGV systems are widely used to increase the flexibility and the efficiency of the material handling systems. AGV systems are one of critical factors which determine the overall performance of the manufacturing systems. To this end, the optimal design for AGV systems is essential. Commercial simulation software is often used as an analysis tool during the design of AGV systems, however a series of procedures are desirable to simplify the analysis processes. In this paper, we present and develop the architecture for unidirectional AGV systems simulator which is able to consider approximate optimal unidirectional flow path and various operational parameters. The designed AGV systems simulator is based on JAVA, and it is developed to support designing approximate optimal unidirectional network by using Tabu search method. In addition, it enables users to design and evaluate AGV systems and to analyze alternative solutions easily. Simulation engine is consists of layout designer, AGV operation plan designer, and integrated AGVS layout designer. Users enter their system design/operation information into input window, then the entered information is automatically utilized for modeling and simulating AGV systems in simulation engine. By this series of procedures, users can get the feed back quickly.