• 한국자동차공학회논문집
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• 제22권4호
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• pp.89-97
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• 2014

As the digital control technologies in automotive industry have advanced, electronic control units(ECUs) play a key-role to improve system performance. Transmission control unit(TCU) is a shifting controller for automatic transmission of which major functions are to determine the shift and manage the shifting process considering the various sensor signal on transmission and driver's commands. As with any ECU in vehicle, TCU performs complex algorithms such as shift control, diagnostic and failsafe functions. However, firmware design analysis is hardly possible by the reverse engineering due to code protection. Transmission simulator is a hardware-in-the-loop simulator which enables TCU to work in normal mode by simulating the electrical signal of TCU interface. In this research, diagnosis and failsafe algorithm implemented on commercialized TCU is analyzed by using the transmission simulator that is developed for wheel loader construction vehicle. This paper gives various experimental results on the proportional solenoid current trajectories for different operating modes, error detection criterion and limphome mode gears for all the possible cases of clutch malfunction. The derived results for conventional TCU can be applied to the development of inherent TCU algorithms and the transmission simulator can also be utilized for the test of TCU to be developed.

• 한국전자통신학회논문지
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• 제8권8호
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• pp.1235-1240
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• 2013

본 논문에서는 색분산이 최적으로 보상된 광통신 시스템에서 자기위상변조와 색분산으로 인해 열화되는 신호의 아이페널티에 대해 근사적인 수학식을 유도하였다. 이러한 분석 연구를 통해 최적으로 색분산 보상된 광통신 시스템에서 신호의 왜곡에 대한 근사식을 얻을 수 있다. 우리는 이 근사식의 효용성을 보이기 위해서 이전 연구의 시뮬레이션 결과와 근사식의 결과를 비교하는 결과를 보인다. 본 논문의 결과를 이용하면 복잡한 비선형 시뮬레이션을 통해 얻을 수 있는 광신호의 왜곡에 대해 손쉽게 그 결과를 예측할 수 있으며, 각종 시스템 파라미터가 시스템에 미치는 영향도 쉽게 파악할 수 있다.

• Journal of Electrical Engineering and Technology
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• 제12권5호
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• pp.2001-2006
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• 2017

This paper explains the effects of the weak signal of a rotating-type electric field mill sensor fabricated for measuring the intensity of the electric field generated by high-voltage direct current (HVDC) power transmission lines. The fabricated field mill consists of two isolated electrode vanes, a motor driver, and a ground part. The sensor plate is exposed to and shielded from the electric field by means of a rotary shutter consisting of a motor-driven mechanically complementary rotor/stator pair. When the uncharged sensor plate is exposed to an electric field, it becomes charged. The rotating electrode consists of several conductive vanes and is connected to the ground part, so that it is shielded. Determining the appropriate design variables such as the speed of the vane, its shape, and the distance between the two electrodes, is essential for ensuring optimal performance. By varying the speed, the weak signal characteristics which is used to signal processing and calibration experiment are quite different. Each weak signal pattern was analyzed along with the output voltage characteristics, in order to be able to determine the intensity of the electric field generated by HVDC power transmission lines with accuracy.

• 한국컴퓨터정보학회논문지
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• 제20권8호
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• pp.7-13
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• 2015

Recently, there are serviced user customized advertisement of various type using smart device. Representative services are advertisement service using light of smart TV screen or audible sound of smart TV to transmit advertisement information. However, those services have to do a specific action of smart device user for advertisement information or need audible audio information of TV contents. To overcome those weakness, therefore, we propose an advertisement method using inaudible sound of speaker based on smart device. This method supports the transfer of advertising content to the smart device user with no additional action or TV audio signal required to access that content. The proposed method used two high frequencies among 18kHz ~ 22kHz of audible frequency range which smart TV can send out. And it generates those frequencies synthesized with audio of TV contents as trigger signal which can send advertisements to smart device. Next, smart device analysis the trigger signal and request advertisement contents related to the signal to server. After then, smart device can show the downloaded contents to user. Because the proposed method uses the high frequencies of sound signals via the inner speaker of the smart device, its main advantage is that it does not affect the audio signal of TV content. To evaluate the efficacy of the proposed method, we developed an application to implement it and subsequently carried out an advertisement transmission experiment. The success rate of the transmission experiment was approximately 97%. Based on this result, we believe the proposed method will be a useful technique in introducing a customized user advertising service.

• 한국전기전자재료학회논문지
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• 제23권10호
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• pp.798-803
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• 2010

This paper describes the characteristics of electromagnetic wave propagation in power transformer. A transformer which is similar to 154 kV single phase on-site transformer unit was provided for the purpose of the experiment. The 12 dielectric windows on the transformer enclosure to install UHF (ultra high frequency) sensors and the full scale mock ups of winding and the core were also equipped in the transformer. Every sensors to be installed to the transformer was tested and verified whether they show same characteristics or not before the experiment. A discharge gap which was used as a PD (partial discharge) source moved to several necessary locations in the transformer to simulate dielectric defects. Propagation times of electromagnetic wave signal from PD source to sensors decided by the routes of both reflection phenomenon and diffraction phenomenon were compared each other. The experimental results showed propagation route of the PD signal makes an effect on the frequency spectrum of front part of the signal and the magnitude of the signal and propagation time of the signal when the signal is captured on the sensor.

• 한국정보통신학회논문지
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• 제15권1호
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• pp.188-194
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• 2011

광결정 광섬유를 포함한 WDM-ROF (wavelength division multiplexing - radio over fiber) 시스템의 고주파신호 전송특성을 분석하였다. 기존의 단일모드 광섬유를 사용한 WDM-ROF 시스템에 있어, 각 WDM 채널의 파장에 따른 고주파신호 전송특성을 분석하였다. 이 경우, 원격노드(remote node)에서의 고주파 신호 특성은 단일모드 광섬유의 분산 특성으로 인해 각 WDM 채널의 파장에 따라 고주파신호 수신 파워의 편차를 나타내게 되며, 이는 전체 시스템 설계시 제한 요소로 작용하게 된다. 광결정 광섬유를 단일모드 광섬유와 함께 사용함으로써 광결정 광섬유의 분산 보상 특성을 이용하여 WDM 채널에 따른 고주파 전송특성을 개선할 수 있음을 확인하였다.

• 한국통신학회논문지
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• 제40권1호
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• pp.124-131
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• 2015

본 논문에서는 Zigbee 무선통신모듈과 RSS(Received Signal Strength) 측위 방식을 이용하여 다단계 TSS(Transmission Signal Strength)기술을 적용한 실내측위 시스템을 제안하고자 한다. 특히 실내공간에서 효과적으로 사용할 수 있는 확률적 알고리즘과 영역인식 알고리즘을 적용하여 위치정+확도에 대한 신뢰를 높이고자 하였다. 또한 1차원공간과 2차원 공간에서의 실험을 통해 공간의 형태에 따라 반사나, 회절, 멀티패스 등의 영향으로 변화하는 전파환경을 고려한 효과적인 측위 시스템을 확인하고자 하였다. 특히 약자나 환자에 대한 긴급 상황 발생 시 해당 위치를 찾아 신속한 대응이 필요하다. 따라서 본 연구의 측위 시스템은 교통 IT 분야에 적용하여 사용 될 수 있을 것으로 기대된다.

• Journal of information and communication convergence engineering
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• 제9권6호
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• pp.676-682
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• 2011

Sybil attack can disrupt proper operations of wireless sensor network by forging its sensor node to multiple identities. To protect the sensor network from such an attack, a number of countermeasure methods based on RSSI (Received Signal Strength Indicator) and LQI (Link Quality Indicator) have been proposed. However, previous works on the Sybil attack detection do not consider the fact that Sybil nodes can change their RSSI and LQI strength for their malicious purposes. In this paper, we present a Sybil attack detection method based on a transmission power range. Our proposed method initially measures range of RSSI and LQI from sensor nodes, and then set the minimum, maximum and average RSSI and LQI strength value. After initialization, monitoring nodes request that each sensor node transmits data with different transmission power strengths. If the value measured by monitoring node is out of the range in transmission power strengths, the node is considered as a malicious node.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 학술회의 논문집 정보 및 제어부문 A
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• pp.27-30
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• 2003

Wireless power transmission system is one of the very interesting field not only in a technical and economical point of view but also that people are still trying to realize lossless power transmission. This paper has a purpose on the efficient power transmission at the passive type ICcard by using wireless power transmission system. The most difficult but important part of the passive type RF-ID system is building the system that supplies power from Reader-antenna to IDcard-antenna. To check what is the most efficient way to deliver power depending on what kind of specifications of the power-amp in reader, antenna and antenna in IDcard is for operating IDcard circuit efficiently receiving the power from reader-antenna. For this, we used 125kHz sinewave for RF signal as a basic specification, power-amp : OP-Amp for amplifying signal and AB Class push-pull power-amp for amplifying power, loop type antenna.

• 드라이브 ㆍ 컨트롤
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• 제15권3호
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• pp.36-42
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• 2018

Agricultural tractors require frequent shifting to improve operation efficiency, and PST (Powershift Transmission) is considered as a suitable transmission. However, due to the inherent characteristics of the PST, shocks arise during shifting, which imparts a negative effect on the operator. Therefore, in order to improve the transmission performance of the tractor PST, researches on various methods including the hydraulic system circuit, the engine input speed control, and the mechanical system of the transmission are steadily being conducted. In this study, in order to reduce the impact of PST on a shift based on SimulationX software, we analyzed the characteristics of the input signal of PCV (Pressure Control Valve) through sensitivity analysis and verified the simulation model through actual vehicle test. Optimization was performed for minimizing the shift shock for some of the parameters of the input signal at constant temperature and RPM conditions.