• Convergence Security Journal
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• v.13 no.6
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• pp.69-76
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• 2013

A lot of researches have been done to improve the energy efficiency of Wireless Sensor Networks. But all the current researches are based on the idea of direct communication between cluster head and sink node. Previous results assume that node can intelligently regulate signal energy according to the distance between nodes. It is difficult to implement algorithms based on this assumption. We present a multi-level routing algorithm from the sink node to all other nodes which have fixed radio wave radius. We also show the energy saving efficiency and the implementation in real WSN using the simulation result.

• Journal of Digital Contents Society
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• v.8 no.4
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• pp.459-465
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• 2007

In this paper, we implemented a ray-tracing simulator with a ray-launching technique and generated the propagation path of each ray in a multiple-wall indoor environment. In this simulator, we adopted two dimension ray-tracing techniques considering the reflection and penetration were dominant propagation factor in the indoor channel. From the result, we verified that this ray-tracing simulator shows the similar path pattern and delay distribution with the experiment results of the previous research. Especially, impulse responses of the ray were corresponding to reference result in non-line of sight of multiple-wall indoor environment. Furthermore, we confirmed that channel profiles having respectively different departure angle 1 degree to 7 degree were similar between them.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.4
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• pp.808-814
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• 2007

In this paper, the measurement system of crane moving range is concerned with range recognition technology using phase and magnitude of radio wave. By the proposed technology, we design the radio transmitter and receiver and realize the measurement system, and save the data in disk that is earned from 900Mhz RF signal, middle frequency 450khz of analog signal. As a result of RF measurement, we got 9.3 dBm of RF output and 96 dBc@10khz of phase noise. Range information is earned the data through digital signal processing of IF signal. For the estimation of range measured, we analyze the difference between real range and measurement range, and also suggest the method to remove the measurement error using average processing and amplitude properties. A result is 0.12 and 0.00422 deviation in l0mn-30m and within 5m respectively, and then 2.4E-04 deviation in 4m by using compensation of level characteristics lately.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.38 no.3
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• pp.57-57
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• 2001

본 논문에서는 RFID를 위한 읽기 전용 CMOS 트랜스폰더를 one-chip으로 설계하였다. 리더에서 공급되는 자기장으로부터 트랜스폰더 칩의 전원을 공급하기 위한 전파정류기를 NMOS 트랜지스터를 사용하여 설계하였으며, 데이터 저장 소자로는 64비트의 ROM을 사용하였다. 메모리에 저장되어 있는 ID 코드는 Manchester 코딩되어 front-end 임피던스 변조 방식으로 리더에 전송된다. 임피던스 변조를 위한 감폭회로로는 리더와 트랜스폰더 사이의 거리가 변해도 일정한 감폭율을 갖는 새로운 감폭회로를 사용하였다. 설계된 회로는 0.65㎛ 2-poly, 2-metal CMOS 공정을 사용하여 IC로 제작되었다. 칩 면적은 0.9㎜×0.4㎜이다. 측정 결과 설계된 트랜스폰더 IC는 인식거리 내에서 약 20∼25%의 일정한 감폭율을 보이며, 125㎑의 RF에 대해 3.9kbps의 데이터 전송속도를 보인다. 트랜스폰더 칩의 전력소모는 읽기 모드시 약 100㎼이다. 인식거리는 약 7㎝이다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.3
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• pp.587-594
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• 2010

In this paper, we propose an asynchronous IR-UWB ranging system based on the two-way ranging protocol. The periodic pulse sequence is used to measure a distance between two devices. At the receiver, a received signal is first transformed into a frequency-domain signal using an analog correlator bank and digital signal processing is followed in the frequency-domain. This make it possible for the system to use an ADC with a conversion speed of pulse rate. The proposed algorithm at the receiver side includes a peak detection procedure using mutipath channel compensation and matched filtering, and retransmits a pulse sequence synchronized with the detected peak. The validity of the proposed algorithm is verified from simulation results where the CM1 channel is assumed.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.08a
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• pp.175-178
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• 2008

In this paper, we introduce the considerations of pseudo range generation process of GNSS system and propose the design structure and show the simulation results applied to GPS. A Pseudo range generation simulator for GNSS(Global Navigation Satellite System) provides the generation function of GNSS constellations, the acquisition function of satellites position, the generation function of true range between satellites and user receiver, the generation functions for individual error features generated through the signal is travelled, and the calculation function of pseudo range. In addition, the simulator is designed to provide the output files of RINEX format.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.10
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• pp.918-926
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• 2007

Military aircrafts usually operate at the area with lots of threats such as radars and surface-to-air missiles. Aircraft also faces with the unexpected or pop-up threats. Under this environment, a safe flight path should be generated to lead a mission successful. In this paper, a new path planning algorithm is proposed to provide less dangerous flight path efficiently. Of many path planning algorithms, a potential method is considered, because it has advantages of computation efficiency and smooth path generation. Trajectory generation under the condition of maximum range is studied so that the aircraft may reach the target area without refueling. The algorithm to cope with an unexpected situation is also proposed by adopting the concept of initial direction vector, additional force, and a new mapping function. The performance of the proposed algorithms is demonstrated for SEAD (Suppression of Enemy Air Defences) mission by numerical simulation.

• Journal of Advanced Navigation Technology
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• v.23 no.5
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• pp.386-391
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• 2019

This paper presents analysis results for the effect of the directional group delay of the antenna to implement a precision radio navigation system. The analysis was conducted through antenna simulation and test, and the test was performed in an anechoic chamber. The directional group delay of the antenna was calculated in phase-based analysis method. The results showed that a variation of up to 7.7ns in group delay occurred per antenna direction. The group delay variation from the analysis is 2.31 meters when converted into distance. It was tested using a real radio navigation system based on the time of arrival (TOA). The test verified the distance variation of 2.1 meters, and this value is similar to those obtained from the simulation and chamber test analysis.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.10a
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• pp.581-584
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• 2011

It is necessary to know what a range is effective for induction to prepare protective measures. In this paper, a simulation is practised to find ranges appropriate to underground transmission and distribution power line. There are two elements for ranges. They are parallelized length and separate distance between a telecommunication line and power line. The legal law presents limited voltages of induction. Simulation means to find what specification range of above two elements the induced voltage is over the limited voltage at. It was simulated that induced voltage for the case of underground power lines was over at the length of about 13km when the separate distance was fixed at 3m.

• Tunnel and Underground Space
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• v.31 no.6
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• pp.578-592
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• 2021

This study performed to investigate the propagation characteristics of overpressure, impulse, vibration in underwater blasting. The difference between air blasting and underwater blasting is that noise and vibration propagate through water as a medium. In some cases, the noise and vibration propagates through various media (rock, water, air, etc.). In this study, the underwater blasting was simulated using AUTODYN, and the propagation characteristics of overpressure, impulse and vibration induced by blasting were analyzed. We mainly focused on the effect of mesh size on the overpressure, impulse and peak particle velocity from the underwater blasting simulation. The numerical results indicated that the overpressure and peak particle velocity tended to decrease as the mesh size increased, while the impulse increased with the mesh size. The results also indicated that the mesh dependence varied depending on the explosive charge and scaled distance.