• Journal of Advanced Navigation Technology
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• v.20 no.5
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• pp.394-400
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• 2016

It is well known that the encrypted ranging signal, such as GPS P(Y) code, is immune to spoofing attack. However, in order for users to use the signal, there needs permission from the operator. And also there are many restrictions for use because of security issues. In this paper, a ground reference station equipped with high-gain directional antenna and a user receiver were simulated. In the reference station, the encrypted code can be demodulated from the high-gain signal. And then the code can be used to detect spoofing attack in the user receiver. This paper proposes the spoofing detection method using the encrypted signal and deals with simulation results.

• The Transactions of the Korean Institute of Power Electronics
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• v.9 no.2
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• pp.163-170
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• 2004

Since 1960s, a container shipping volume has increased dramatically and continuous on a trend of rapid growth, and so the number of containers handled at the port increases. The position measurement of the yard crane is very important for improving the operating efficiency of the port. This paper describes the method to measure the absolute position of yard crane accurately and rapidly, using both the output pulse of an encoder and infrared sensors. The crane position is calculated by counting the output pulse of an incremental encoder, which is mounted on the wheel in the crane. By the way, the wheel slippage on rail may cause some errors in the crane position information obtained from encoder pulse, and the infrared sensor is used to compensate for errors in the crane position information. The performance of proposed method is verified on experimental results with the simulator of yard crane, the size of which is about 1/10 with the real crane.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.3
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• pp.301-307
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• 2002

A multilayer ceramic chip antenna with helical structure is analyzed to enhance the narrow bandwidth of conventional ceramic chip antennas. The simulations are performed by HFSS to verify the effects of structural parameters on impedance bandwidth. The multilayer ceramic chip antennas consist of a rectangular-parallelepiped ceramic body$({\varepsilon}_r=7.8,\; tan\; {\delta}=0.0043)$ and helical conductor patterns are embedded in the ceramic body using LTCC-MLC technology. 3D structure design of the multilayer ceramic chip antenna suitable for IMT-2000 (1,920~2,170 MHz) handset has been implemented, and experimental results are presented and discussed.

• Proceedings of the Korean Information Science Society Conference
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• 2003.10c
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• pp.685-687
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• 2003

최근 국내우주개발 중장기계획에 따라 지구관측위성, 통신위성, 기상위성 등 다양한 위성개발이 추진되고 있으나, 선진국들이 첨단 위성의 기술이전을 기피함에 따라 국내주도의 독자적인 차세대위성의 개발 필요성이 대두되고 있다. 그러나 새로운 위성의 설계, 제작, 조립 및 시험, 검증에는 많은 시설 및 장비가 필요하며 오랜 기간과 많은 예산이 소요된다. 이를 해결하기 위해 새로운 위성의 개발 시 선진국에서는 범용위성 개발 테스트베드(Flight System Testbed)를 제작하여 사전에 위성시스템을 모델링 및 검증함으로서 개발기간의 최적화, 개발예산의 최소화, 신기술의 적용 등에 활용하고 있는 추세이다. 국내의 경우, 위성의 지상관제와 운용요원의 교육을 위해 위성시뮬레이터를 제작하여 확용하는 단계이나, 새로운 위성 개발을 위한 위성전자전산시스템 개발검증장비 및 활용기술은 전무한 상태이다. 향후 다양한 위성임무에 대응한 위성의 개발기간 단축 및 비용절감과 첨단 위성전자시스템 및 부품기술의 사전 검증을 위해 위성 전자전산시스템 개발검증장비에 대한 연구가 필수적이다. 본 논문에서는 해외 위성선진국에서의 위성전자전산시스템에 대한 기술에 대해 살펴보고 현재까지 진행된 차세대 위성개발을 위한 위성시스템 개발검증 장비의 설계에 대해 알아보고자 한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.7A
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• pp.935-942
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• 2000

In this paper, miniature voltage-controlled oscillator(VCO) for 1.6GHz PCS band is designed and implemented. Colpitts type LC resonating oscillator is designed with multilayer PCB and circuit parameters are optimized using the circuit simulator. Using the optimized design parameters, miniature VCO with 6X6X1.8mm3 (0.065cc)dimensions is fabricated and experimented. Developed VCO has -1.67dBm $\pm$0.5dBm output power level in52.5MHz tunung range, and has -99.33dBc/Hz phase noise performance at 10 KHz frequency offset.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.49 no.4
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• pp.55-60
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• 2012

When operating a surveillance system in the maritime environment, its stabilization performance is degraded due to undesirable disturbance motions. For accurate target pointing of a 2-axes surveillance system on shipboard, the kinematic stabilization is first applied, which compensates a deviated motion via coordinate transformations of attitude information. Resultantly, the stabilization error is no longer reduced due to less accuracy of a MEMS sensor and kinematic constraint, leading to introduction of the image stabilization as a complementary function. And for real-time execution of the present dual stabilization scheme, a HILS (Hardware In the Loop Simulation) test bed including 6-dof motion simulator has been constructed, and through the obtained HILS data, it has been confirmed that the stabilization is successfully.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.17 no.3
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• pp.103-109
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• 2003

The validity of measured data is fundamental factor for the power system automation Measured values could have errors that are caused by the communication errors and malfunctioning measuring devices. The accuracy and reliability of measured values at a substation is an important condition for robust and fault tolerant automata. Errors can be reduced by state estimation, however, global reliability of state estimation goes down in case of the existence of some bad data In this paper, a least square state estimation and bad sensor detection algorithm based on chi-square theory, ale proposed and it is applied to a domestic 154kV distribution substations. A simulator together with user friendly graphic users interface is developed using C language and Visual Basic. TCP/IP is equipped for future connection with other operation systems.

• Progress in Medical Physics
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• v.22 no.3
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• pp.155-162
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• 2011

The analog image based system consisted of a simulator and medical linear accelerator (LINAC) for radiotherapy was upgraded to digital medical image based system by exchanging the X-ray film with Computed Radiography (CR). With minimum equipments shift and similar treatment process, it was possible that the new digital image system was adapted by the users in short time. The film cassette and the film developer device were substituted with a CR cassette and a CR Reader, where the ViewBox was replaced with a small size PC and a monitor. The viewer software suitable for radiotherapy was developed to maximize the benefit of digital image, and as the result the convenience and the effectiveness was improved. It has two windows to display two different images in the same time and equipped various search capability, contouring, window leveling, image resizing, translation, rotation and registration functions. In order to avoid any discontinuance of the treatment while the transition to digital image, the film and the CR was used together for 1 week, and then the film developer was removed. Since then the CR System has been operated stably for 2 months, and the various requests from users have been reflected to improve the system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.12
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• pp.910-917
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• 2018

This paper describes the developments to improve the feeling and safety of the remote control system of unmanned vehicles. Generally, in the case of the remote control systems, a joystick-type device or a simple steering-wheel are used. There are many cases, in which there are operations without considering the feedback to users and driving feel. Recently, as the application area of the unmanned vehicles has been extended, the problems caused by not considering the feedback are emphasized. Therefore, the need for a force feedback-haptic control arises to solve these problems. In this study, the force feedback-haptic control algorithm considering the vehicle parameters is proposed. The vehicle parameters include first the state variables of dynamics, such as the body side-slip angle (${\beta}$) and yawrate (${\gamma}$), and second, the parameters representing the driving situations. Force feedback-haptic control technology consists of the algorithms for general and specific situations, and considers the situation transition process. To verify the algorithms, a simulator was constructed using the vehicle dynamics simulation tool with CAN communication environment. Using the simulator, the feasibility of the algorithms was verified in various scenarios.

• Journal of the Korean Society for Marine Environment & Energy
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• v.12 no.1
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• pp.15-22
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• 2009

Auto-navigation algorithm have been studied to avoid collision and grounding of a ship due to human error. There have been many research on collision avoidance algorithms but they have been validated little on the real coastal traffic situation. In this study, a Collision Avoidance algorithm is developed by using Fuzzy algorithm and the concept of Changeable Action Space Searching (CAS). In the first step, on a basis of collision risk calculated from fuzzy algorithm in the current time(t=to), alternative Action Space for collision avoidance is planned. In the second step, next alternative Action Space for collision avoidance in the future($t=to+{\Delta}t$) is corrected and re-planned with re-evaluated collision risk. In the third step, the safest and most effective course among Action Space is selected by using optimization method in real time. In this paper, the main features of the developed collision avoidance algorithm (CAS) are introduced. CAS is implemented in the ship-handling simulator of MOERI. The performance of CAS is tested on the situation of open sea with 3 traffic ships, whose position is assumed to be informed from AIS. Own-ship is fully autonomously navigated by autopilot including the collision avoidance algorithm, CAS. Experimental results show that own-ship can successfully avoid the collision against traffic ships and the calculated courses from CAS are reasonable.