• Journal of Internet Computing and Services
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• v.15 no.4
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• pp.1-8
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• 2014

In wireless body sensor system(WB-SNSs), unlike existing sensor network system, the size of device is small and amount of battery is considerably limited. And various channel environments can be made by link channel characteristic, human movements, sensor placements, transmission power control(TPC) algorithms and so on. In this paper, therefore we take diverse experiments with totally considerated environments to overcome these restrictions and to manage the energy efficiently and find the value of target received signal strength indicator(RSSI) based on diverse factors such as human movements, sensor placements, and TPC algorithms. And we conduct analysis in terms of energy consumption and packet delivery rate(PDR) based on the experimental results. Through these analysis, we compare and evaluate the efficiency according to setup values of Target RSSI and Target RSSI range suitable for wireless body sensor network system.

• Journal of Satellite, Information and Communications
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• v.2 no.2
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• pp.64-68
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• 2007

This paper describes the development of RF front.end equipment of a wide band high precision satellite navigation receiver to be able to receive the currently available GPS navigation signal and the GALILEO navigation signal to be developed in Europe in the near future. The wide band satellite navigation receiver with high precision performance is composed of L - band antenna, RF/IF converters for multi - band navigation signals, and high performance baseband processor. The L - band satellite navigation antenna is able to be received the signals in the range from 1.1 GHz to 1.6 GHz and from the navigation satellite positioned near the horizon. The navigation signal of GALILEO navigation satellite consists of L1, E5, and E6 band with signal bandwidth more than 20 MHz which is wider than GPS signal. Due to the wide band navigation signal, the IF frequency and signal processing speed should be increased. The RF/IF converter has been designed with the single stage downconversion structure, and the IF frequency of 140 MHz has been derived from considering the maximum signal bandwidth and the sampling frequency of 112 MHz to be used in ADC circuit. The final output of RF/IF converter is a digital IF signal which is generated from signal processing of the AD converter from the IF signal. The developed RF front - end has the C/N0 performance over 40dB - Hz for the - 130dBm input signal power and includes the automatic gain control circuits to provide the dynamic range over 40dB.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2000.08a
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• pp.141-144
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• 2000

현재 로프제조 공정, 전차 트롤리선 가설공사는 장력의 제어가 필요하지만 거의 수동으로 행하고 있는 실정이고 제품의 균질성과 생산성 향상을 위하여 제조 공정의 자동화가 필요하다. 따라서 전차의 트롤리선 가설공사는 드럼에 감긴 케이블을 풀어주고 양단의 장력을 일정히 유지하도록 조절할 필요가 있다. 따라서 본 연구의 목적은 현수형 가선 케이블 가설장치의 자동화이다. 본 논문은 제어대상인 현수형 케이블의 수학적 모델을 작성하고 이것에 장력을 발생하는 교류서보 전동기의 수학적 모델을 구하였다. 제어 방법은 제어대상의 동적 모델이 비선형인 동시에 시변계이기 때문에 강인성이 있는 퍼지제어를 적용하여 시스템을 구성하고 시뮬레이션 실험에 의해 그 유효성을 평가하였다.

• Journal of Broadcast Engineering
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• v.27 no.6
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• pp.914-922
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• 2022

In this paper, we construct a commercial 4K UHD(Ultra High Definition) streaming device that utilizes a 5G mobile communication network as a transport channel and conduct a streaming performance test. It uses RTP(Realtime Transport Protocol) which has transmission quality monitoring capability as a transmission protocol to apply adaptive streaming. In addition, it provides the function to adjust the encoding rate of the video signal so that encoding can be optimized for the change in the bandwidth of the transmission channel. Through the performance test, it is confirmed that the H.265 encoding rate for 4K UHD signal is 48.69Mbps, the average glass-to-glass delay time is 293.60ms, and the average time difference between video and audio for lip sync is 120ms. With the result of performance test, it is shown that the streaming device is applied to 4K UHD Streaming device over 5G mobile communication network.

• Korean Journal of Crystallography
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• v.8 no.1
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• pp.38-47
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• 1997

A new weighing sensor for the automatic diameter control system of the crystal growth is developed in this study. This weighing sensor measures the frequency of the vibrating element which is lineally changing with respect to weight. The signal and the power of this system are transmitted without any physical contact, so that this sensor offers high accuracy and resolution. This system consists of a string, a sinusoidal wave generator, an automatic amplification adjusting circuit, signal transformers and a PCB. 4 kinds of programs are developed for checking DAC, weight calibration and controlling growth process. The measurements of the standard deviation and the resolution show $\pm0.10g$(measured at every second) and $5{\times}10^{-5}$, respectively, This weighing sensor is effective under high pres-sure of 200 atm, high temperature and vacuum condition. The weighing system can control the temperature in the accuracy of $\pm0.025^{\circ}C$ with the 'signal divider'. The optical quality single crystals of $(YGd)_3Sc_2Ga_3O_{12},\;Er-Y_3Sc_2Al_3O_{12},\;and\;Bi_{12}GeO_{20}$ have been grown by Czo-chralski method using this auto-diameter control system.

• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.6
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• pp.1156-1169
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• 1989

본 연구에서는 용접도중 발생할 수 있는 용접질 저항요인을 전극분리현상을 측정하여 파악하고 용접 열입력에 해당하는 용접전류를 학습제어방식(self-learning control)에 의하여 컴퓨터와 주변기기(interface)를 통해 조절함으로서 요구되는 균일한 용접질이 항상 보장되도록 하였다. 여기서 학습제어방식을 태택한 이유는 제어하고자 하는 대상의 동적 모델(dynamic model)이 없어도 제어기 이득의 선정이 비교적 자유롭고 용접 제어장치가 자체적으로 감지(monitoring)한 신호로 판단하여 제어동작을 취함으로서 용접시 축적되는 정보(data)가 용접기에 일종의 지능을 부여할 수 있어서 진보된 개념의 용접제어장치 개발의 가능성을 검토해 보기 위함이다.

• Proceedings of the Korean Nuclear Society Conference
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• 1995.10a
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• pp.352-357
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• 1995

원자력발전소 화학 및 체적제어계통의 일부인 밀봉수주입계통은 원자로 냉각재펌프 밀봉장치로 일정한 온도 범위의 밀봉수를 공급하여 밀봉장치의 건전성 및 원자로 냉각재 계통의 압력경계를 유지한다. 그러나 발전소 과도상태시 밀봉수 주입온도가 허용범위를 벗어나게 되면 온도조절기 폐쇄신호에 의해 밀봉장치로의 밀봉수 주입이 차단될 수 있다. 본 연구에서는 발전소 과도시에도 밀봉수 주입이 지속적으로 가능한 설계개선 방안으로 밀봉수주입 열교환기 주위에 우회라인을 설치하는 방안을 제시하고 밀봉수주입 열교환기 내에서의 비정상 열전달 현상을 수치해석을 이용하여 분석하였다. 계산은 속도장을 정상 상태인 power-law분포로 가정하고 시간 t=0에서 입구온도가 급격히 변하는 과도시 우회 유량 및 시간 변화에 대한 온도분포, 국부 Nusselt 수, 평균온도 등을 구하였다.

• Proceedings of the KIEE Conference
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• 2007.10a
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• pp.273-274
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• 2007

최근에 각광받는 영상표시 장치인 LCD와 PDP는 Progressive 방식으로 영상을 표시하며 화질 또한 SD에서 HD로 바뀌었다. 따라서 대용량의 데이터를 빠른 시간에 FPD 패널로 전송해야 하며 이를 위해 LVDS 전송 방법을 사용한다. 대부분의 화질 테스트 장비들은 빠른 데이터 전송을 위해 내부에 저장되어 있는 특정 패턴들만 LVDS 신호로 바꾸어 패널로 전송하게 되며 저장되어 있는 영상을 움직이는 것도 제한적이다. 하지만 LCD 패널의 응답속도, PDP 패널의 DFC등을 테스트 하기 위해서는 다양한 패턴이 필요하며 영상의 움직임 또한 자유롭게 조절할 수 있어야 한다. 따라서 본 논문에서는 다양한 패턴을 다운로드받아서 표시할 수 있는 테스트 장비를 설계하고 USB를 통해 테스트 장치 컨트롤 및 이미지 다운로드를 할 수 있는 프로그램을 설계하여 고정세 FPD의 화질을 테스트 할 수 있는 시스템을 구현하고자 한다.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.7
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• pp.225-230
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• 2013

In a bandpass sampling (BPS), the frequency of the sampler is lower than that of the signal being sampled. In this method, the baseband spectrum directly appears by the sampling operation, so that it is not necessary to use any frequency down-converter, which makes the receiver's hardware simpler. The second-order BPS uses two identical BPS samplers, of which sampling times are offset by each other. By exploiting the relationship between two sampled signals, it can be possible to cancel the aliased signal component or the interference due to the bandpass sampling. In order to cancel the interference, an interpolant filter is used to manipulate the phase characteristics of the BPS sampled signal. In this paper, it is introduced a multiband interpolant filter which can simultaneously cancel multiple interference signals that have been aliased from multiple frequency bands. In case of no need of interference cancellation, another method is suggested to enhance the signal quality by 3dB. A computer simulation has been performed, and the feasibility of the suggested methods has been verified.

• Journal of the Korean Society of Radiology
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• v.14 no.7
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• pp.965-973
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• 2020

The purpose of this study was to quantitatively correlate the change of flow velocity and signal voiding in TOF-MRA. We made our phantom to control the flow velocity, and changed the flow velocity in 16 steps from 8.0 to 127.3 mc/s. The TOF-MRA test was performed using a 3.0T MRI system and the signal intensity was measured by classifying the signal voiding length and image into the In flow, Mid flow, and Out flow. The length of signal voiding was the longest when the flow velocity was 127.3 cm/s and the signal intensity decreased with increasing flow velocity(p<0.05). In flow(-.547) and Mid flow(-.643) were negatively correlated with flow velocitys(p<0.05). In conclusion, it was confirmed that the increase in flow velocity was a major factor causing signal voiding in TOF-MRA. In the future, this study will provide basic data when studying sequences and parameters to reduce signal voiding in models with a high flow velocity.