• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.33 no.8
• /
• pp.1-7
• /
• 2005

This paper proposes a local improvement method that combines extended topological clean up and optimization-based smoothing for homogenizing triangular grid system. First extended topological clean up procedures are applied to improve the connectivities of grid elements. Then, local optimization-based smoothing is performed for maximizing the distortion metric that measures grid quality. Using the local improvement strategy, we implement the grid homogenizations for two triangular grid examples. It is shown that the suggested algorithm improves the quality of the triangular grids to a great degree in an efficient manner and also can be easily applied to the remeshing algorithm in adaptive mesh refinement technique.

• Proceedings of the Korean Information Science Society Conference
• /
• 2000.04a
• /
• pp.148-150
• /
• 2000

자원 예약을 보장하지 못하는 네트워크 상에서 실시간 멀티미디어 응용의 만족스러운 서비스를 위해서는 효과적인 종단 시스템의 운영이 필요하다. 이러한 운영 기술 중 버퍼를 이용한 응용 프로그램 수준의 대역폭 평활화 기술과 태스크 스케줄링 기법은 핵심적인 부분을 차지한다. 기존에 제안된 온라인 대역폭 평활화 기법은 동적 슬라이딩 윈도우와 공적 버퍼를 이용하여 네트워크에 적응할 뿐만 아니라 요구 대역폭 평활화를 통해 지터를 흡수, 완충시킴으로써 더 나은 서비스 품질을 보장한다. 그러나 응용 프로그램 수준에서 동작하기 때문에 프로그램의 수행 품질보장을 위한 시간 대역을 보장하지 못할 뿐만 아니라 지터의 발생 가능성이 높다. 본 연구에서는 효과적인 버퍼 관리를 통해 서비스 품질의 손실을 최소화하는 적응성 있는 온라인 대역폭 평활화 기법이 안정적으로 동작하기 위한 최적화된 태스크 스케줄링 기법을 제안한다. 먼저 태스크 스케줄링 기법은 멀티미디어 데이터의 생산과 소비를 적시에 보장할 수 있도록 하여 지터의 발생을 최소화하고, 만일 네트워크 지터가 발생하더라도 응용 프로그램 수준의 버퍼 관리를 통해 완충시킴으로서 서비스 품질의 손실을 최소화한다. 모의 실험에서는 제안된 기법이 온라인 대역폭 평활화 기법을 효과적으로 지원함을 보인다.

• Journal of Korean Society for Geospatial Information Science
• /
• v.17 no.1
• /
• pp.149-155
• /
• 2009

To quantitatively analyze the positioning error due to the ionosphere over the Korean peninsula, we created 2-dimensional ionosphere map using 44 permanent Global Positioning System(GPS) stations operated by Ministry of Land, Transport, and Maritime Affairs. We estimated Vertical Total Electron Content(VTEC) in a fine rectangular grids of $0.1^{\circ}{\times}0.1^{\circ}$ resolution. The observables we used were phase-leveled pseudoranges which are linear combinations of pseudoranges and carrier phases. VTECs were computed for five days during January 25-29, 2003 using the data from 45 permanent stations. In comparison with the Global Ionosphere Map of the Center for Orbit Determination in Europe, RMS differences were at the level of 8 TECU(TEC Unit).

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.54 no.10
• /
• pp.443-448
• /
• 2005

To measure modulus, damping properties and smoothness of semiconducting materials in power cable, we have investigated those of semiconducting materials showed by changing the content of carbon black. Then they were produced as sheets after pressing for 20 minutes at 180[$^{\circ}C$] with a pressure of 200[kg/cm$^{2}$]. The content of conductive carbon black was the variable, and their contents were 20, 30 and 40[wt$\%$], respectively. The modulus and tans were measured by DMA 2980. The ranges of measurement temperature were from -50[$^{\circ}C$] to 100[$^{\circ}C$] and measurement frequency was 1[Hz3. The modulus of specimens was increased according to a increment of a carbon black content. And modulus was rapidly decreased at the glass transition temperature. The tans of specimens was decreased according to a increment of a carbon black content. The smoothness was measured by JSM-6400. EEA resin from SEM measurement was best the dispersion of carbon back in base resin.

• Journal of KIISE
• /
• v.42 no.12
• /
• pp.1561-1567
• /
• 2015

Abstract Semi-supervised learning is an area in machine learning that employs both labeled and unlabeled data in order to train a model and has the potential to improve prediction performance compared to supervised learning. Graph-based semi-supervised learning has recently come into focus with two phases: graph construction, which converts the input data into a graph, and label inference, which predicts the appropriate labels for unlabeled data using the constructed graph. The inference is based on the smoothness assumption feature of semi-supervised learning. In this study, we propose an enhanced label inference algorithm by incorporating the importance of each vertex. In addition, we prove the convergence of the suggested algorithm and verify its excellence.

• The Journal of the Korea Contents Association
• /
• v.5 no.6
• /
• pp.378-385
• /
• 2005

Mistaking normal packets for harmful traffic may not offer service in conformity with the intention of attacker with harmful traffic, because it is not easy to classify network traffic for normal service and it for DDoS(Distributed Denial of Service) attack. And in the IPv6 environment these researches on harmful traffic are weak. In this dissertation, hosts in the IPv6 environment are attacked by NETWOX and their attack traffic is monitored, then the statistical information of the traffic is obtained from MIB(Management Information Base) objects used in the IPv6. By adapting the ESM(Exponential Smoothing Method) to this information, a normal traffic boundary, i.e., a threshold is determined. Input traffic over the threshold is thought of as attack traffic.

• Journal of the Korean Data and Information Science Society
• /
• v.23 no.1
• /
• pp.79-87
• /
• 2012

In the case that the probability density function has a discontinuity point, Huh (2002) estimated the location and jump size of the discontinuity point based on the difference between the right and left kernel density estimators using the one-sided kernel function. In this paper, we consider the cross-validation, made by the right and left maximum likelihood cross-validations, for the bandwidth selection in order to estimate the location and jump size of the discontinuity point. This method is motivated by the one-sided cross-validation of Hart and Yi (1998). The finite sample performance is illustrated by simulated example.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1999.05a
• /
• pp.493-496
• /
• 1999

Ni/3C-SiC 옴믹 접합에 대한 미세구조적-접합 특성과의 상관관계를 규명하였다. 3C-SiC 웨이퍼 위에 저저항 전면 옴믹 적합층을 형성하기 위하여 Ni(t=300$\AA$)을 thermal evaporator를 사용하여 증착하고, 50$0^{\circ}C$, 80$0^{\circ}C$, 103$0^{\circ}C$ 온도에서 30분간(Ar 분위기) 열처리 한 후, scratch test를 실행하여 Ni/3C-SiC의 접착력 특성을 조사하였다. 여러 다른 온도에 따른 Ni/3C-SiC 층의 표면과 계면의 미세구조는 X-ray scattering 법을 사용하였다. 50$0^{\circ}C$ 에서 열처리된 Ni/3C-SiC 층은 가장 낮은 계면 평활도와 가장 높은 표면 평활도를 나타내었다. Ni/3C-SiC 접착력 분석에서 500 $^{\circ}C$ 열처리된 시편의 측정된 임계하중 값은 As-deposited 시편(12 N~ 13 N)보다 훨씬 낮은 2 N~3 N 범위의 값을 보였으나, 열처리 온도가 증가함에 따라 다시 높아지는 경향을 보였다. 미세구조 특성에서는 열처리 온도가 500 $^{\circ}C$ 이상에서는 NiSi$_2$silicides의 domain size는 결정성의 향상에 따라 증가되었다. 결정성 향상이 3C-SiC와 silicides 사이의 격자상수의 낮은 불일치를 완화시키는데 기여 하였 다.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.33 no.2
• /
• pp.691-702
• /
• 2013

In this study the quantitative outlier-filtering algorithm has been developed using the smoothing method based on the day-of-the-week traffic volume variation pattern and then, in order to test the effectiveness of the algorithm, it has been used to identify outliers from the traffic volume data collected at 14 continuous traffic counts sites on the national highways in the year 2010. The test results are satisfactory since the filtering rate is 98.2% for normal days and the mis-filtering rate is 8.0% for abnormal days. Therefore, the algorithm will be able to be used for roughly-but-quickly filtering outliers from the collected traffic volume data.

• Korean Journal of Materials Research
• /
• v.7 no.5
• /
• pp.417-422
• /
• 1997

본 연구에서는 LPCVD, PECVD, ECR plasma CVD방법을 이용하여 x선 노광 공정용 마스크의 투과막재료로써의 실리콘질화막의 증착과 그의 물성에 관하여 실험하였다. X선 노광 마스크용 투과막의 재질로써 요구되는 적정인장응력에 가지는 증착조건으로 실리콘질화막을 1$\mu\textrm{m}$정도의 두께로 증착하였으며 이 조건에서의 물성을 SIMS, XPS, ESR, AFM, spectrophoto-metry를 이용하여 비교 분석하였다. ECR plasma CVD방법으로 얻은 실리콘 질화막은 화학양론적 조성(Si/N=0.75)에 근접하는 막을 얻을 수 있었으며 표면 평활도와 가시광투과도가 가장 우수한 결과를 얻었다. 저온 증착법인 PECVD로 얻은 막은 Si/N비가 약 0.86정도이고 산소와 수소의 불순물함량이 가장 높게 나타났다. SiH$_{2}$CI$_{2}$를 이용한 LPCVD막의 경우는 Si-rich조성을 가지지만 수소 불순물의 함량이 가장 작게 나타났고 표면거칠기는 가장 나쁘게 나타났다. 그러나 위의 방법으로 얻은 실리콘 질화막의 최대 가시광투과도는 633nm파장에서 모두 90%이상의 값을 나타내었고, 또한 표면 평활도도 0.64-2.6nm(rms)로 현재 연구되고 있는 다른 X선 투과막재료보다 월등히 우수한 결과를 보였다.