• 전기학회논문지
• /
• 제66권9호
• /
• pp.1373-1378
• /
• 2017

This paper presents a basic ECU(Electronic Control Unit) hardware development procedure for the functional safety of in-vehicle network systems. We consider complete hardware redundancy as a safety mechanism for in-vehicle communication network under the assumption of the wired network failure such as disconnection of a CAN bus. An ESC (Electronic Stability Control) system is selected as an item and the required ASIL(Automotive Safety Integrity Level) for this item is assigned by performing the HARA(Hazard Analysis and Risk Assessment). The basic hardware architecture of the ESC system is designed with a microcontroller, passive components, and communication transceivers. The required ASIL for ESC system is shown to be satisfied with the designed safety mechanism by calculation of hardware architecture metrics such as the SPFM(Single Point Fault Metric) and the LFM(Latent Fault Metric).

• 한국정보통신학회논문지
• /
• 제17권9호
• /
• pp.1986-1995
• /
• 2013

수집된 전자 정보 신호를 분석하여 활동 중인 레이더를 식별하는 ELINT 시스템은 현대 전자전에서 매우 중요한 역할을 담당한다. 수집된 신호로부터 추출할 수 있는 여러 레이더 운용 변수 중 펄스 내 변조 방식은 점점 고도화되는 레이더의 식별에 필수적인 정보이다. 본 논문은 퍼지 알고리즘을 이용하여 수집 신호에 적용된 펄스 내 변조 방식을 인식하는 기법을 제안한다. 제안하는 기법은 신호를 특징짓기 위한 퍼지 멤버십 함수와 이를 이용하여 적용된 변조방식을 추론하기 위한 퍼지 추론 규칙을 정의한다. 실험 결과는 제안된 기법이 SNR 10dB 이상의 수집 환경 하에서 95% 이상의 변조 방식 인식률을 보장함을 보인다.

• 한국군사과학기술학회지
• /
• 제14권1호
• /
• pp.69-73
• /
• 2011

In the defence wireless communications, conventional Anti-Jamming techniques(Frequency Hopping/Spread Spectrum or Direct Sequence/Spread Spectrum) are used to overcome a intentional interfering signals which are single/multitone or partial band jammer etc. DS/SS techniques is very strong on tone jamming signal but not to be on a partial band jammer. So FH/SS AJ performances are expected method of an substitution of DS/SS, however FH/SS could not have good performance on some BMTJ(Band Multi-tone Jammer). So this paper proposes FH-CSS (Frequency Hopped - Chirp Spread Spectrum) to get more robustness against jammers(BMTJ, PBNJ) and analyze the AJ performances.

• Current Optics and Photonics
• /
• 제1권6호
• /
• pp.598-603
• /
• 2017

Traditional three-dimensional (3-D) laser imaging systems are based on real aperture imaging technology, whose resolution decreases as the range increases. In this paper, we develop a novel 3-D imaging technique based on the synthetic aperture technology in which the imaging resolution is significantly improved and does not degrade with the increase of the range. We consider an imaging laser radar (ladar) system using the floodlight transmitting mode and multi-beam receiving mode. High 3-D imaging resolutions are achieved by matched filtering the linear frequency modulated (LFM) signals respectively in range, synthetic aperture along-track, and the real aperture across-track. In this paper, a novel 3-D imaging signal model is given first. Because of the motion during the transmission of a sweep, the Doppler shift induced by the continuous motion is taken into account. And then, a proper algorithm for the 3-D imaging geometry is given. Finally, simulation results validate the effectiveness of the proposed technique.

• Tribology and Lubricants
• /
• 제18권1호
• /
• pp.1-8
• /
• 2002

Nano adhesion and friction between a $Si_{3}N_{4}$ AFM(atomic force microscope) tip and thin silver films were experimentally studied. Tests were performed to measure the nano adhesion and friction in both AFM and LFM(lateral force microscope) modes in various range of normal loads. Thin silver films deposited by IBAD (ion beam assisted deposition) on Si-wafer (100) and other Si-wafers of different surface roughness were used. Results showed that nano adhesion and friction decreased with the surface roughness. When the Si surfaces were coated by pure silver, the adhesion and friction decreased. But the adhesion and friction were not affected by the thickness of IBAD silver coating. As the normal force increased, the adhesion forces of bare Si-wafer and IBAD silver coating film remained constant, but the friction forces increased linearly. Test results suggested that the friction was mainly governed by the adhesion as long as the load was low.

• 한국윤활학회:학술대회논문집
• /
• 한국윤활학회 2001년도 제34회 추계학술대회 개최
• /
• pp.35-42
• /
• 2001

Nanotribological characteristics between a Si$_3$N$_4$ AFM tip and hydrophobic thin films were experimentally studied. Tests were performed to measure the nano adhesion and friction in both AFM(atomic force microscope) and LFM(lateral force microscope) modes in various ranges of normal load. Plasma-modified thin polymeric films were deposited on Si-wafer (100). Results showed that wetting angle of plasma-modified thin polymeric film increased with the treating time, which resulted in the hydrophobic surface and the decrease of adhesion and friction. Nanotribological characteristics of these surfaces were compared with those of other hydrophobic surfaces, such as DLC, OTS and IBAD-Ag coated surfaces. Those of OTS coated surface was superior to those of others, though wetting angle of plasma-modified thin polymeric film is higher.

• 한국항공우주학회지
• /
• 제34권8호
• /
• pp.104-108
• /
• 2006

항공기나 위성에 탑재되어 지표면의 영상을 획득하기 위한 합성 개구 레이더의 영상 분해능은 거리 방향 분해능(Range Resolution)과 이에 수직한 방향의 분해능(Azimuth Resolution)으로 구분할 수 있다. 레이더 센서를 이용한 영상의 해상도를 향상시키기 위해서는 신호처리를 위한 첩 펄스를 광대역화 할 필요가 있으며, 본 논문에서는 고해상도의 영상을 획득 할 수 있는 디지털 첩 펄스 발생기를 설계하였다. 디지털 첩 펄스 발생기는 크게 AWG방식과 DDS방식으로 구분할 수 있으며 본 연구에서는 DDS방식의 첩 펄스 발생기로 선형 주파수 변조(LFM) 파를 발생시키는 300MHz 대역의 광대역 디지털 첩 펄스 발생기를 개발하였다. 개발된 첩 펄스 발생기는 거리 방향 분해능이 50cm 이상 되는 고해상도 영상 레이더 시스템을 구현할 수 있는 성능을 가진다.

• The Journal of the Acoustical Society of Korea
• /
• 제17권1E호
• /
• pp.54-65
• /
• 1998

This study attempts to test the classifying performance of a neural network and thereby examine its applicability to the signals distorted in a shallow water environment. Linear frequency modulated(LFM) signals are simulated by using an acoustic model and also measured through sea experiment. The network is constructed to have three layers and trained on both data sets. To get normalized power spectra as feature vectors, the study considers the three transforms : shot-time Fourier transform (STFT), wavelet transform (WT) and pseudo Wigner-Ville distribution (PWVD). After trained on the simulated signals over water depth, the network gives over 95% performance with the signal to noise ratio (SNR) being up to-10 dB. Among the transforms, the PWVD presents the best performance particularly in a highly noisy condition. The network performs worse with the summer sound speed profile than with the winter profile. It is also expected to present much different performance by the variation of bottom property. When the network is trained on the measured signals, it gives a little better results than that trained on the simulated data. In conclusion, the simulated signals are successfully applied to training a network, and the trained network performs well in classifying the signals distorted by a surrounding environment and corrupted by noise.

• 전기학회논문지
• /
• 제65권12호
• /
• pp.2030-2036
• /
• 2016

This paper presents a hardware development procedure of the ASB(Active Seat Belt) control system to comply with ISO 26262. The ASIL(Automotive Safety Integrity Level) of an ASB system is determined through the HARA(Hazard Analysis and Risk Assessment) and the safety mechanism is applied to meet the reqired ASIL. The hardware architecture of the controller consists of a microcontroller, H-bridge circuits, passive components, and current sensors which are used for the input comparison. The required ASIL for the control systems is shown to be satisfied with the safety mechanism by calculation of the SPFM(Single Point Fault Metric) and the LFM(Latent Fault Metric) for the design circuits.

• 반도체디스플레이기술학회지
• /
• 제14권4호
• /
• pp.1-7
• /
• 2015

People are always pursuing the aesthetic feeling relentlessly. But some people have such problems with their hairs like alopecia, cancer chemotherapy, burns, and scalp injury. So the synthetic hair has played a very important role to make up for these deficiencies. But long term use can lead to adverse reactions or uncomfortable feeling. This is primarily caused by its properties differ with human hair. In particular, nanotribological characterizations (roughness, friction force and adhesive force) of synthetic hair surface are dissatisfy with the needs of normal hairs. This paper presents the experiments on nanotribological characterizations measurements of human hairs (coloring hair, permed hair and common hair) in shampooing condition or without shampooing condition. Using atomic force microscopy (AFM) to find out a range of synthetic hair nanotribological characterizations which can correspond with natural hair. The measurements of nanotribological characterizations focus on surface roughness, friction force and adhesive force, and a new design of AFM probe was used for measuring the nanotribological characterizations.