• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 통신소사이어티 추계학술대회논문집
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• pp.172-175
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• 2003

In this paper we propose a method fur the evaluation of the quality of service for VoIP services in NGN. Specifically, let us anatomize the elements of delay of a voice connection in the network in an end-to-end manner and investigate expected value at each point. We extract the delay time in each element in the network such as gateway, network node, and terminal equipment, and estimate an upper bound fur the tolerable delay in each element.

• Current Optics and Photonics
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• 제3권3호
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• pp.193-198
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• 2019

We propose a novel method to design a dispersion map for a WDM (Wavelength Division Multiplexing) ring network with the capability of wavelength reconfiguration. The method is simple, but gives us an optimum set of DCMs (Dispersion Compensation Modules) which satisfies a given value of the tolerable residual dispersion. The proposed method does not depend on compensation method, fiber type, or modulation format. We also demonstrate numerically how it works with an example 10-node ring network.

• 한국정보시스템학회지:정보시스템연구
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• 제26권3호
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• pp.187-209
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• 2017

Purpose The sharing economy is the most important keyword that is changing the paradigm of the world economy and management, and it was selected as one of 10 ideas to change the world in 2011 in Time magazine. The purpose of this study is to verify the structural relationship between perceived value and risk, network effect, usefulness, trust, and intention to use of accommodation service. In addition, the effects of utility and trust, and the experience of using accommodation service are controlled by the effect of empirical value and reciprocal value among the perceived value of sharing economic service, The purpose of this study is to propose a plan to activate the accommodation sharing service. Design/methodology/approach This study was designed to investigate the structural relationship between perceived value, perceived risk, network effect, usefulness, trust, and intention to use. Empirical analysis was done using SPSS 21.0 and AMOS 21.0 Findings Based on the results of this study, the following conclusions can be drawn. First, it was concluded that the higher the economic value of the accommodation sharing service is, the more useful and reliable the service is. Second, the higher the experiential value of the accommodation sharing service is, the higher the usefulness and reliability of the service are. Third, it was concluded that the higher the value of the mutual benefit of the accommodation sharing service is, the higher the trust level of the service is, but not the usefulness of the service. Fourth, it was concluded that the higher the perceived risk of accommodation sharing service is, the lower the service trust level is, but the service usability is not affected. Fifth, it was concluded that the larger the network effect of the accommodation sharing service is, the more useful the service is, but it does not affect the reliability of the service. Sixth, it was concluded that the higher the overall reliability of the accommodation sharing service is, the higher the usefulness of the service is. Seventh, it was concluded that the higher the overall usefulness and reliability of the accommodation sharing service are, the higher the intention to use the sharing service is. Finally, in order to test the effect of the experience on the use of trust and usefulness of the accommodation sharing service, multiple group analysis was conducted to examine the relationship between trust and usefulness, It is shown that there is a moderating effect in the path.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.511-514
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• 2002

In may automated systems such as manufacturing systems and process plants, an industrial network or fieldbus is a very important component for the exchange of various and sometimes crucial information. Some of the information has a tendency to rapidly lose its value as time elapses after its creation. Such information or data is called real-time data that includes sensor values and control commands. In order to deliver these data in time, the fieldbus network should be tailored to have short delay with respect to the individual time limit of various data. Fine-tuning the network for a given traffic requires the knowledge on the relationship between the protocol parameters such as timer values and the performance measure such as network delay. This paper presents a mathematical performance model to calculate communication delays of the Profibus FMS network when the timer value TTR and the traffic characteristics are given. The results of this model is compared to those from experiments to assess the model's validity.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2003년도 총회 및 춘계학술발표회
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• pp.259-262
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• 2003

In the Republic of Korea, Ministry of Construction & Transportation and Korea Water Resources Corporation manage the national groundwater monitoring network at the 169 stations and will organize the supplementary groundwater monitoring network at the 10,000 stations by 2011 year. The method that organizes the monitoring network was developed using the Analytic Hierarchy Process with pairwise comparison. Several estimation factors for the estimating every district were selected to reflect each district conditions. Their weighting value was decided by pairwise comparison and questions to the experts about groundwater The optimal number of groundwater monitoring well was calculated through the developed method. To verify this method, groundwater was monitored in Jeonju city by way showing the example. The study area In Jeonju city needs 7 stations for the supplementary groundwater monitoring network. The results monitored in 7 stations inferred the groundwater level around the study area by Kriging. The mean of residual between inferred groundwater level value from Kriging and actual groundwater level is rather low. Furthermore, the mean and standard deviation of residual between inferred groundwater level change and actual groundwater change is much lower. The Fact that 7 monitoring stations are sufficient for observing the groundwater condition in the study area makes it possible for suggested monitoring number to be proper.

• 전자공학회논문지CI
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• 제41권3호
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• pp.37-45
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• 2004

본 논문에서는 이동 에드-혹 네트워크에서 조합가중치 클러스터링 알고리즘을 적용하여 강건하고 신뢰성 있는 클러스터 기반의 그룹 멀티캐스트 방식을 제안한다. 에드-혹 네트워크는 고정된 통신 하부 구조의 도움 없이 이동 단말기로만 구성된 무선 네트워크이다. 제한된 대역폭과 높은 이동성으로 인하여 에드-혹 네트워크에서의 라우팅 프로토콜은 강건하고, 간단하면서 에너지 소비를 최소화하여야 한다. WCGM(Weighted Cluster Group Multicast)방식은 조합 가중치 다중 클러스터 기반 구조를 이용하고 기존의 FGMP(Forwarding Group Multicast Protocol)방식의 장점인 제한적인 플러딩에 의한 데이터 전달방식은 유지하면서 클러스터 헤드 선출 시 조합가중치를 적용한다. 이것은 안정적이며 강건한 데이터 전달 구조를 가지기 때문에 데이터 전달 구조를 유지하기 위한 오버헤드(Overhead)와 데이터 전달을 위한 오버헤드를 모두 줄이는 효과를 시뮬레이션을 통하여 검증하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 C
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• pp.1880-1884
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• 2000

The discrete wavelet transform is utilized as preprocessing of Neural Network(NN) to identify aging state of internal partial discharge in transformer. The discrete traveler transform is used to produce wavelet coefficients which are used for Classification. The statistical parameters (maximum of wavelet coefficients, average value, dispersion, skewness, kurtosis) using the wavelet coefficients are input into an back-propagation neural network. The neurons whose weights have obtained through Result of Cross-Validation. The Neural Network learning stops either when the error rate achieves an appropriate minimum or when the learning time overcomes a constant value. The networks, after training, can decide if the test signal is Early Aging State or Last Aging State or normal state.

• 전자공학회논문지CI
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• 제44권2호
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• pp.11-18
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• 2007

신경회로망의 학습에 널리 사용되고 있는 오차역전파 알고리즘은 최급하강법을 기초로 하고 있기 때문에 초기값에 따라서는 극소값에 떨어지거나, 신경회로망을 학습시킬 때 중간층 유닛수를 얼마로 설정하는 등의 문제점이 있다. 따라서 이러한 문제점을 해결하기 위하여, 본 논문에서는 3비트 패리티 판별을 위하여 신경회로망의 학습에 교차법, 돌연변이법에 새로운 기법을 도입한 개량형 유전적 알고리즘을 제안한다. 본 논문에서는 세대차이, 중간층 유닛수의 차이, 집단의 개체수의 차이에 대하여 실험을 실시하여, 본 방식이 학습 속도의 면에서 유효하다는 것을 나타낸다.

• 디지털콘텐츠학회 논문지
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• 제10권2호
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• pp.279-289
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• 2009

TCP는 전송 비트 오류에 의한 패킷 손실 확률이 매우 낮은 유선망을 대상으로 설계된 프로토콜이므로, 이를 그대로 유 무선 통합 환경에 적용할 경우 TCP 송신단이 무선망의 제한된 대역폭, 높은 대기 시간, 높은 비트 에러율, 임시적인 연결 끊김 등의 특성에 의해 발생하는 패킷 손실도 네트워크 혼잡에 의한 것으로 가정하여 송신단 전송률을 낮추기 때문에 성능이 저하하게 된다. 본 논문에서는 Snoop을 기반으로 BS에 Threshold 와 Lower Bound을 이용한 새로운 개선된 프로토콜을 제안한다. 이 기법은 무선 패킷 손실을 빠르게 복구하기 위하여 무선링크의 상태에 따라서 기지국의 지역 재전송 타이머를 효과적으로 조정한다. 제안한 알고리즘을 다양한 시뮬레이션을 통하여 제안한 프로토콜이 Snoop프로토콜에 비하여 연속한 패킷 손실이 발생하는 무선 링크에서 패킷 손실을 효과적으로 복구하여 TCP전송률을 향상시키는 것을 확인하였다.

• 한국정보처리학회논문지
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• 제7권2호
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• pp.552-557
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• 2000

본 논문에서는 신경망의 초기 파라미터(가중치, 바이어스) 값을 최적화 시키는 GA-BP(Genetic Algorithm-Backpropagation Network) 혼합 알고리즘을 이용하여 얼굴을 인식하는 방법을 제안하였다. 입력 영상의 각 픽셀들을 신경망의 입력으로 사용하고 고정 소수점 실수값으로 이루어진 신경망의 초기 파리미터 값은 유전자 알고리즘의 개체로 사용하기 위해 비트 스트링으로 변환한다. 신경망의 오차가 최소가 되는 값을 적합도로 정의한 뒤 새롭게 정의된 적응적 재학습 연산자를 이용하여 이를 평가해 최적의 진환된 신경망을 구성한 뒤 얼굴을 인식하는 실험을 하였다. 실험 결과 학습 수렴 속도의 비교에서는 오류 역전과 알고리즘 단독으로 실행한 수렴 속도보다 제안된 알고리즘의 수렴 속도가 향상된 결과를 보였고 인식률에서 오류 역전과 알고리즘 단독으로 실행한 방법보다 2.9% 향상된 것으로 나타났다.