• The Bulletin of The Korean Astronomical Society
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• v.35 no.2
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• pp.60.1-60.1
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• 2010

한국우주전파관측망(Korean VLBI Network, KVN)을 이루는 21m 망원경의 수신기에는 전파세기를 모니터링하기 위한 장치가 있으나, 회로잡음, 이득, 그리고 DC offset 등의 개선을 위하여 전파세기 시험용 측정기를 설계하였다. 이 장치는 입력신호의 전압에 대하여 주파수로 출력되는데, 선형성과 신호잡음특성이 중요하다. 이러한 회로 특성 파악과 개선을 위하여, 차동입력 증폭, 단일입력 증폭, 그리고 1:1앰프출력 등으로 입력신호에 대하여 다양한 실험을 할 수 있게 하였고, 샘플링 주파수도 1 MHz와 4 MHz를 선택할 수 있게 전파세기 시험용 측정기를 설계하였다. 시제품을 제작하여 DC 입력 시험, 0 전압입력 시험, 노이즈 제너레이터를 이용한 동작 시험, 그리고 KVN연세전파천문대의 수신기에 직접 연결한 실험을 통하여, 최종 이득안정도의 잡음스펙트럼 ~1.5 X $10^{-4}\;dG/G(Hz^{-1/2})$@1Hz를 얻었다. 이번 실험 결과를 바탕으로 KVN의 전파세기측정기를 새로 제작할 예정이다. 이에 전파세기 시험용 측정기의 설계 결과를 소개하고자 한다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.12
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• pp.2265-2270
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• 2007

This paper discusses a tester of functionality and call processing performance, based on the MEGACO/H.248 protocol that both IETF and ITU-T recommend as a media gateway control protocol, of both a media gateway controller and an access gateway which constitute a next generation convergence network. Effective methods, a functional architecture and implementation for such testification are provided. Especially included are not only a virtual emulation function of analog subscriber lines connecting to an access gateway, but also a tester emulated as a counter system of the protocol for the testifying a media gateway controller and an access gateway system.

• Electronics and Telecommunications Trends
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• v.13 no.1 s.49
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• pp.14-20
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• 1998

본 논문은 대도시 전화망에서 루팅 효과, 통화량에 준한 망설계기법에서 전송시설의 경제적 규모, 그리고 투자비용 변화를 분석하기 위한 시뮬레이션 모델 개발에 관한 것이다. 모의시험 결과는 전화망에서 교환/전송에 소요되는 비용은 루팅방식의 변경에 따라서 크게 영향을 받으며, 고속 전송로 사용에 따른 규모의 경제효과가 클수록 망 구축에 소요되는 비용이 현저히 작아지는 것으로 나타났다.

• TTA Journal
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• s.92
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• pp.86-91
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• 2004

초기에 많은 관심과 투자가 집중되었던 VoIP 서비스가 여러 가지 이유로 그 동안 침체되어 왔으나, 향후 통신 서비스 사업자의 차세대 네트워크 및 광대역 통합망 도입과 함께 각종 규제와 제도가 정비됨에 따라 점차 활성화될 것으로 예상하고 있다. 본 고에서는 향후 수요가 증가할 것으로 기대되는 VoIP 장비 시험 인증에 대해 현재 TTA에서 제공하는 있는 시험 서비스에 대해 소개한다.

• KIPS Transactions on Computer and Communication Systems
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• v.8 no.4
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• pp.79-86
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• 2019

This paper describes a time-series data prediction based on artificial neural networks (ANN). In this study, a batch based ANN model and a stochastic ANN model have been implemented using TensorFlow libraries. Each model are evaluated by comparing training and testing errors that are measured through experiment. To train and test each model, tax dataset was used that are collected from the government website of indiana state budget agency in USA from 2001 to 2018. The dataset includes tax incomes of individual, product sales, company, and total tax incomes. The experimental results show that batch model reveals better performance than stochastic model. Using the batch scheme, we have conducted a prediction experiment. In the experiment, total taxes are predicted during next seven months, and compared with actual collected total taxes. The results shows that predicted data are almost same with the actual data.

• The Bulletin of The Korean Astronomical Society
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• v.35 no.1
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• pp.44.1-44.1
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• 2010

한국천문연구원에서는 2009년 1단계 한일공동VLBI상관기(Korea-Japan Joint VLBI Correlator, KJJVC)의 개발과 설치를 완료하였다. KJJVC는 한국우주전파관측망(Korean VLBI Network, KVN), KVN과 일본 내의 VLBI 관측망을 포함하는 한일공동VLBI관측망(Korea-Japan Joint VLBI Network, KJJVN), 그리고 한중일의 VLBI관측망인 동아시아 VLBI관측망(East Asian VLBI Network, EAVN)으로 관측한 VLBI 데이터를 상관처리할 수 있도록 설계 제작되었다. 그리고 고속재생기, 데이터 동기재생처리시스템(Raw VLBI Data Buffer, RVDB), VLBI상관서브시스템(VLBI Correlation Subsystem, VCS), 데이터 아카이브 시스템(Peta-scale Epoch Data Archive, PEDA)로 구성된다. 특히 일본국립천문대 VERA에서는 테이프 형태의 DIR2000 고속기록기를 사용하고 있는데, DIR2000의 제품단종으로 인해 이 데이터를 VCS에 재생하기 위해 DIR1000을 개량한 VERA2000 고속재생기를 개발하였다. 즉, VSI 형태의 데이터를 1Gbps 속도로 재생만 하기 위해 기존의 시스템을 개량하였으며, 2009년 10월에 VLBI상관기실에 설치되었다. 본 논문에서는 VERA2000 시스템의 구성 및 개발, 시험운영 등에 대해 간략히 소개하고자 한다.

• Journal of the Korean Geotechnical Society
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• v.17 no.6
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• pp.25-36
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• 2001

The purpose of this paper is to discuss the effects of soil properties such as liquid limit, water content, etc. on the compression index and to propose the empirical equation of compression index far regional clay and to verify the application Back Propagation Neural Network(BPNN). The compression index values obtained from laboratory tests are in the range of 0.01 to 3.06 for clay soils sampled in eleven regions. As the compare with the results of laboratory test and the predicted compression index value from the proposed empirical equations, the results of empirical equations including single soil parameter have a possibility to be overestimated. Also, the results of empirical equations including multiple soil parameters closed to the measured value more than that of empirical equations including single soil parameter, but the standard error for measured value obtained larger than 0.05. For these reasons, the empirical equations including single or multiple soil parameters proposed base on the results of laboratory test and the determination coefficient is up to 0.89. The result of BPNN shows that correlation coefficient and standard error between test and neural network result is larger than 0.925 and smaller than 0.0196, which means high correlativity, respectively. Especially, the estimated result by neural network, using only three parameters such as natural water content, dry unit weight and in-situ void ratio among various factors is available to the estimation of compression index and the correlation coefficient is 0.974. This result verified the possibility that if BPNN use, the compression index can be predicted by the parameters, which obtained from simplex field test.

• Information and Communications Magazine
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• v.12 no.12
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• pp.25-36
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• 1995

• Journal of KIISE:Software and Applications
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• v.33 no.10
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• pp.836-850
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• 2006

Nowadays, due to the rapidly increasing number of package software products, quality test has been emphasized for package software products. When testing software products, one of the most important factors is to select metrics which form the bases for tests. In this paper, the types of package software are represented as characteristic vectors having probabilistic relationships with metrics. The characteristic vectors could be regarded as indicators of software type. To assign the metrics for each software type, the past test metrics are collected and analyzed. Using Bayesian belief network, the dependency relationship network of the characteristic vectors and metrics is constructed. The dependency relationship network is then used to find the proper metrics for the test of new package software products.

• Journal of the Korean GEO-environmental Society
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• v.13 no.6
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• pp.5-17
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• 2012

The study of surface ground reinforcing method is supposed to be considered preferentially is not satisfied and also doesn't contemplate plastic flow because of repetitive drive of construction equipment. Also, Terzaghi's bearing-capacity equation and Yamanouchi's suggestion have been used to design the surface reinforcement, but most engineers depend on their experience and cases constructed before because of dispersed variables and inappropriate bearing-capacity factors. Hence, plate load test and repetitive plate load test were performed in the field which is reinforced with geotextile, Geogrid whose tensile strength are 200kN/m, 100kN/m and bamboo($0.4m{\times}0.4m$). The object of this study is to evaluate bearing capacity and behaviour of surface ground and to compare each reinforcement form test results. From the results bearing capacity ratio increased by a maximum of 1.5 times with bamboo reinforcement method comparing to others.