• 정보저장시스템학회논문집
• /
• 제8권2호
• /
• pp.50-55
• /
• 2012

Optical disks are widely used in libraries and archives as digital data media due to their long-term storage stability. Though archive-grade optical disks are already available on the market, there is a relative less focusing on the reliable recording conditions. Commercial BD-R media were recorded at various recording speeds with the maximum speed of 6X, and tested at the acceleration aging conditions. Through the evaluation of long-term storage features by the data stability test, lower recording speed of 2x resulted in better long-term storage stability. In addition, degradation aspects of unstable long-term storage feature at outer region of disk were discussed.

• 한국음향학회지
• /
• 제39권2호
• /
• pp.69-76
• /
• 2020

본 논문은 수중 고속 이동체의 심도 정보를 전송하는 방법을 다룬다. 고속 이동체로부터 전송되는 심도 정보신호는 높은 주파수 변동성을 갖고 수신된다. 제안한 방법에서는 기존의 방법처럼 주파수 동기화뿐만 아니라 시간 축에서 추가로 동기화 하는 방법을 적용하였다. 최대 50 kn로 이동하는 환경에서 수행된 모의실험을 통하여 기존의 방법보다 낮은 해상도를 갖는 도플러 주파수 뱅크를 형성하고, 제안한 방법을 사용하여 심도 정보를 복구한 경우 기존에 6 % ~ 9 %이었던 오류율이 0.2 % ~ 1 %로 낮아진 오류 성능을 나타내었다.

• 대한교통학회지
• /
• 제14권4호
• /
• pp.107-129
• /
• 1996

Recently, surveillance system designed to collect various trsffic information are becoming new areas of development . Among these, the image detector is a ayatem which can measure the travel time and speed in realtime and this is emerging as the most effcient tool to be available in future related areas. But in measuring wide-area information in realtime, the image detector are yet full of problem in its accuracy. The aim of this ahesis is to develop an algorithms which can collect wide-area information such as travel time and travel speed in urban networks and freeways in realtime. The information on wide-area such as travel time and travel speed is important in accomplishing strategic function in traffic control. The algorithm developed from this study is based on the image tracking model which tracks a moving vehicle form image datas collected continuously, and is constructed to perform realtime measurement. To evaluate the performance of the developed algorithms, 600 ind vidual vehicles in total were used as data for the study, and this evaluation was carried out with the differenciation of day and night condition at the access roads in front of AJou University, In the statistical analysis results, the error rate was recorded as 5.69% and it has proved to be applicable on the field in both day and noght conditions.

• 소성∙가공
• /
• 제27권6호
• /
• pp.331-338
• /
• 2018

Electrohydraulic forming (EHF) process is a high speed forming process that utilizes the electric energy discharge in fluid-filled chamber to deform a sheet material. This process is completed in a very short time of less than 1ms. Therefore, finite element analysis is essential to observe the deformation mechanism of the material in detail. In addition, to perform the numerical simulation of EHF, the material properties obtained from the high-speed status, not quasi static conditions, should be applied. In this study, to obtain the parameters in the constitutive equation of Al 6061-T6 at high strain rate condition, a surrogate model using an artificial neural network (ANN) technique was employed. Using the results of the numerical simulation with free-bulging die in LS-DYNA, the surrogate model was constructed by ANN technique. By comparing the z-displacement with respect to the x-axis position in the experiment with the z-displacement in the ANN model, the parameters for the smallest error are obtained. Finally, the acquired parameters were validated by comparing the results of the finite element analysis, the ANN model and the experiment.

• 한국전자파학회논문지
• /
• 제28권12호
• /
• pp.948-953
• /
• 2017

초고속 통신을 위해 HPA(High Power Amplifier)를 사용할 때, HPA의 비선형 특성은 전력 효율 및 BER(Bit Error Rate) 성능 및 스펙트럼 효율 등을 열화시키는 원인이 된다. 초고속 통신을 위한 충분한 송신 전력을 얻기 위해서는 HPA의 사용이 불가피하므로 사전왜곡기를 사용하여 HPA의 비선형성을 보상시켜줄 필요가 있다. 본 논문에서는 HPA의 비선형성을 보상해주기 위한 용도의 사전왜곡기를 HPA의 앞단에 사용하여 비선형 왜곡을 보상하여, 이를 성좌도, 스펙트럼, BER 성능 등으로 비교하여 분석하였다. 시뮬레이션 결과, 사전왜곡기를 사용하여 HPA의 비선형성을 보상해줌으로써 이상적인 선형 증폭기와 비슷한 수준의 BER 성능을 얻을 수 있었으며 스펙트럼 마스크도 충족하는 것을 확인할 수 있었다.

• 전자공학회논문지CI
• /
• 제43권4호
• /
• pp.73-79
• /
• 2006

터보 코드는 강력한 에러정정 성능 때문에 W-CDMA(Wideband Code Division Multiple Access), CDMA2000 등의 통신 알고리즘에 적용되고 있으며, 여러 분야에서 하드웨어로 구현되어졌다. 여러 가지의 개선 알고리즘과 하드웨어 구조가 제안되어 졌으나 아직까지 하드웨어 면적, 동작속도 및 소비전력 등의 문제가 연구되어지고 있다. 본 논문에서는 하드웨어 면적과 동작속도를 향상시키기 위하여 사후확률 최적화로부터 유도된 MAX-SCALE 알고리즘을 이용한 터보코드 복호기를 설계하였으며, 제안된 회로는 Matlab과 MaxPulsII를 사용하여 성능 측정 및 FPGA 보드상에 구현되었다. 결과적으로 제안된 구조를 사용하여 FPGA에 구현했을 때, 616개의 로직 요소 (Logic Element)를 가지며 MAP(Maximum a Posteriori) 복호 알고리즘에 비해 동작속도는 56.48MHz로 약 40% 향상되었으며, 6.12%의 BER(Bit Error Rate) 성능이 향상되었다.

• 대한의용생체공학회:학술대회논문집
• /
• 대한의용생체공학회 1993년도 춘계학술대회
• /
• pp.129-131
• /
• 1993

A transcutaneoos information transmission system using transmitted infrared light for an implantable total artificial heart(TAH) an developed and the performance of the system was tested. In an in vitro test, transmittance of the developed system was measured through various thicknesses of pig shins. In an in vivo test, a loopback test using a personal computer was performed to determine the error rate and an experiment using a mock system was taken. In this experiment, within acceptable lateral and vertical displacements, the error rate of at least 3.8E-6 was guaranteed. Monitoring signals from the internal controller(Intel 87C196) of the mock system were successfully transmitted to the external controller(IBM PC) and the operating commands from the external controller were successfully conducted by the mock system. Communication was done in half duplex mode according to RS-232 protocol at the speed of 4800 bps.

• Journal of electromagnetic engineering and science
• /
• 제11권4호
• /
• pp.274-281
• /
• 2011

High-speed telecommunication systems are influenced by electromagnetic environments because they need a wide bandwidth to transmit signals. Immunity tests of telecommunication equipment are effective for improving its immunity to electromagnetic environments. However, immunity tests are expensive to carry out because there are several different tests. The correlation among the tests should therefore be examined in order to reduce the kinds of tests that are necessary. This paper investigates the correlation between the electrical fast transient/burst (EFTB) test and the radio frequency (RF) conductive immunity test. Imitation equipment was constructed with a balun, and a baseband signal was transmitted from the associated equipment to the imitation equipment. Then, disturbances were applied to the equipment, and the telecommunication quality was evaluated by using the bit error rate (BER). The results from the EFTB test indicated that the BER was less than $6{\times}10^{-5}$ and the value was independent of the peak value. The results from the RF conductive immunity test indicated that the BER was affected by the longitudinal conversion loss (LCL).

• 한국통신학회논문지
• /
• 제27권1A호
• /
• pp.1-12
• /
• 2002

초광대역 통신은 전 주파수 대역에 걸쳐 스펙트럼이 마치 기저 대역 잡음과 유사한 형태로 존재하여 타 통신시스템에 간섭을 주지 않고 고속의 통신이 가능하며, 반송파를 사용하지 않기 때문에 송${\cdot}$수신기의 소비 전력과 그 구조를 간략화 시킬 수 있다. 본 논문에서는 평균값이 0이고 대칭성을 갖는 레일리 모노펄스 Antipodal 방식을 처음으로 적용하여 초광대역 신호를 구성하고 시간 도약 부호를 적용하여 다중접속 시스템을 제안하였다. AWGA에서 레일리 모노펄스에 대한 오류확률, 다중접속시 사용자의 수, 전송속도에 대해 수치해석을 통해 시스템의 성능을 비교, 분석하였다. 그 결과 제안한 Antipodal 방식은 기존의 펄스 위치 변조 방식보다 오류확률, 사용자의 수 및 전송속도 면에서도 유리함을 보였다.

• 융합신호처리학회논문지
• /
• 제24권1호
• /
• pp.1-14
• /
• 2023

Underwater images carry information that is useful in the fields of aquaculture, underwater military security, navigation, transportation, and so on. In this research, we transmitted an underwater image through various underwater mediums in the presence of underwater turbulence and beam attenuation effects using a high-speed visible optical carrier signal. The optical beam undergoes scintillation because of the turbulence and attenuation effects; therefore, distorted images were observed at the receiver end. To understand the behavior of the communication media, we obtained the bit error rate (BER) performance of the system with respect to the average signal-to-noise ratio (SNR). Also, the structural similarity index (SSI) and peak SNR (PSNR) metrics of the received image were evaluated. Based on the received images, we employed suitable nonlinear filters to recover the distorted images and enhance them further. The BER, SSI, and PSNR metrics of the specific nonlinear filters were also evaluated and compared with the unfiltered metrics. These metrics were evaluated using the on-off keying and binary phase-shift keying modulation techniques for the 50-m and 100-m links for beam attenuation resulting from pure seawater, clear ocean water, and coastal ocean water mediums.