• 한국정보통신학회논문지
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• 제20권10호
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• pp.1831-1836
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• 2016

본 논문에서는 차세대 위성통신 규격인 DVB-RCS2 기반 VSAT 단말 시스템의 송수신부 위상잡음 스펙트럼 분포 특성을 분석한다. VSAT 순방향 링크는 DVB-S2 ACM 기반 APSK 고차 전송모드를 사용하며, 역방향 링크는 DVB-RCS2 기반 PSK 및 QAM 계열의 고차 전송 모드를 사용한다. 고차 전송 모드를 사용함에 따라 위상잡음에 의한 영향이 나타나며, 위성전송시스템 신호발생부의 위상잡음 특성에 따라 전송 성능의 열화가 지배적으로 나타난다. 위성전송 환경에 따라 가변적으로 전송 데이터 율와 전송 모드를 가변하는 전송방식을 고려하여 요구 위상잡음 특성을 분석하고 차세대 VSAT 전송 파라미터를 수용하는 전송시스템 신호발생부의 위상잡음 특성을 제시한다.

• 한국전자통신학회논문지
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• 제14권2호
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• pp.361-368
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• 2019

본 논문은 전기차 기반의 1톤급 상용차용 통합공조 시스템에 관한 연구이다. 전기 상용차의 경우 화물의 승하차를 위해 문의 개폐가 빈번하게 이루어지기 때문에 열손실이 크게 발생한다. 따라서 냉난방 부하가 승용 전기차에 비해 더 크게 요구된다. 결과적으로 승객이 요구하는 열 쾌적성을 만족하기 위해서 냉난방 시스템이 소비하는 에너지가 승용 전기차 보다 크다. 이러한 단점을 극복하기 위해 효율적인 통합공조 시스템을 적용한 연구를 수행했다. 최종적으로 1톤급의 경상용 전기트럭의 상품성 개선과 전기트럭 분야의 산업 생태계 기반 확충을 위한 고효율 공조 시스템 개발을 위해 냉방을 위한 전동식 압축기와 난방을 위한 히트펌프 시스템의 구상 설계와 해석적 검증을 수행한다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 학술대회 논문집 정보 및 제어부문
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• pp.43-45
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• 2004

A remote monitoring system was developed to improve inconveniences of manual work such as monitoring street lights by using current sensors, microprocessor and RF communication system. In order to control the street lights on the roads effectively and monitor them in real time, we can attach current sensor to the street lights which monitors Lamp, the broken part and state of the Balast, and the amount of an electric leak precisely we developed a system which makes it possible to transmit the data on monitoring results in breakdown of street lights and Balasts to the central monitoring computer without setting up extra data transmission line. The system we devised can transmit data through Power Line Modem and RF communication using relay method to the central controlling computer without any loss of data.

• 한국정보통신학회논문지
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• 제19권5호
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• pp.1071-1076
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• 2015

본 논문은 장력 센서 시스템으로 구성된 장력펜스에 무선모듈을 설치하고, 경보발생시 데이터를 무선으로 전송하는 알고리즘을 연구한다. 유선 통신 시스템은 높은 정확성과 응답속도를 가지지만 초기 설치비용이 비싸고 연결이 복잡하며 연결선이 유실되는 문제가 발생할 수 있다. 이러한 이유로 Zigbee 무선통신 기술을 이용하여 유선 통신 시스템의 문제점을 보완하고 무선 통신이 가지는 응답속도 지연 및 배터리 문제에 관해 연구하여 이를 적용하고자 한다.

• 전자공학회논문지A
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• 제33A권6호
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• pp.32-41
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• 1996

We propose the improved GMSK (gaussian-filtered minimum shift keying) quadrature modulator using the FIR(finite impulse response )filter whose coefficients are obtained form the differnce of phase response, and design its ASIC (applicaton specific integrated circuit) which can be used for GSM (global system for mobile communication) digital cellular system and DCS 1800 (digital cellular system at 1800MHz) personal communication system. Input data become quantized I and Q channel 10 bit signal through cosine and sine ROM mapping after being filtered by the FIR filter whose normalized bandwidth is 0.3 and designed by considering intersymbol interference as well as sampling ratio. These two signals become the GMSK modulated I and Q channel signal through DAC (digital-to-analog converter) and 7th order analog chebyshev LPF(low pass filter) respectively. The difference between the ideal analog signal and its digitized signal is analyzed in terms of sampling noise, quantization noise, truncation noise and coefficient noise. And the effect of the LPF following the DAC is considered. The ASIC design of the GMSK quadrature modulator is also confirmed by an experiment.

• 한국멀티미디어학회논문지
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• 제9권6호
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• pp.735-741
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• 2006

In the near future, the wireless home networks will connect several devices at home. Due to the broadcast nature of a wireless network, anyone can hear and capture communication. Thus, we need to protect our network from attacks outside the house. In this paper, we propose and implement a security system that provides different levels of the security services to heterogenous home devices. To reduce the communication cost and workload of the server, home devices send the encrypted messages directly instead of sending through the sever. We implement our security system on laptops using JAVA and our security system achieves the better performance with the large number of devices and messages in a network. In order to prove that our security system is secure against various attacks, we analyze the security of our security system using attack trees.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 D
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• pp.2780-2782
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• 2002

In this paper Valentine Braitenberg structure based sensory motor model for object tracking control system was proposed. Conventional model based control schemes are require highly non-linear mathematical models, which require long computational time to solve complex high order equations. Contrast to conventional models proposed system simply link signal data from camera directly to the inputs of neural network, and outputs of network are directly fed into input of motor driver of camera. With simple structure of sensory motor model, real time tracking control system for dynamic object was realized successfully, and the implementation of sensory motor model can overcome the limitation of model-based control schemes.

• 한국국방경영분석학회지
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• 제26권1호
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• pp.56-69
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• 2000

A frequency assignment problem on time division duplex system is considered. Republic of Korea Army (ROKA) has been establishing an infrastructure of tactical communication (SPIDER) system for next generation and it will be a core network structure of system. VHF system is the backbone network of SPIDER, that performs transmission of data such as voice, text and images. So, it is a significant problem finding the frequency assignment with no interference under very restricted resource environment. With a given arbitrary configuration of communications network, we find a feasible solution that guarantees communication without interference between sites and relay stations. We formulate a frequency assignment problem as an Integer Programming model, which has NP-hard complexity. To find the assignment results within a reasonable time, we take a genetic algorithm approach which represents the solution structure with available frequency order, and develop a genetic operation strategies. Computational result shows that the network configuration of SPIDER can be solved efficiently within a very short time.

• 대한원격탐사학회지
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• 제2권1호
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• pp.49-54
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• 1986

This study has been intended to design an optimum meteorological information system appropriate for Korea as a part of 5 year development plan. The 5 year plan was that to set up new direction in order to modernize meteorological data acquisition, processing and information distribution. The detailed research has been led to presentation of optimum meteorological information system of Korea eventually, selecting the computerization of communication as the primary object of modernization. In the study, research concerning effective equipment configuration, data communications internal as wall as external, and the related implementations has been carried out with the approach of system component consideration under system application design. As tile results of the study, integrated network of meterorological data communication was presented including earth quakes, radar, aerologic, marine weather observations and so on.

• International Journal of Internet, Broadcasting and Communication
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• 제13권2호
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• pp.7-13
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• 2021

Machine vision is a technology that helps the computer as if a person recognizes and determines things. In recent years, as advanced technologies such as optical systems, artificial intelligence and big data advanced in conventional machine vision system became more accurate quality inspection and it increases the manufacturing efficiency. In machine vision systems using deep learning, the image quality of the input image is very important. However, most images obtained in the industrial field for quality inspection typically contain noise. This noise is a major factor in the performance of the machine vision system. Therefore, in order to improve the performance of the machine vision system, it is necessary to eliminate the noise of the image. There are lots of research being done to remove noise from the image. In this paper, we propose an autoencoder based machine vision system to eliminate noise in the image. Through experiment proposed model showed better performance compared to the basic autoencoder model in denoising and image reconstruction capability for MNIST and fashion MNIST data sets.