• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.3
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• pp.751-762
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• 1995

The snapshot method is introduced to approximate the coherent structures of planar jet flow. The numerical simulation of instantaneous flow field is analyzed by SIMPLE algorithm. An ensemble of realizations is collected using a sampling condition that corresponds to the passage of a large scale vortex at positions 4 and 6 diameters downstream from the nozzle. With snapshot mothod we could treat the data efficiently and approximate coherent structures inhered in the planar jet flow successfully 94% of total turbulent kinetic energy with 10 terms of Karhunen-Loeve expansions. Finally, In accordance with the recent trend to try to explain and model turbulence phenomena with the existence of coherent structures, in the present study, we express the underlying coherent structures of planar jet flow in the minimum number of modes by calculating Karhunen-Loeve expansions in order to improve to understanding of jet flow and to make the information storage and management in computers easier.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.05a
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• pp.720-723
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• 2001

현재 인터넷 환경에서 크래킹은 보편화되어 있다. 이러한 크래킹을 탐지하거나 방어하기 위한 기법들은 대부분 기존의 불법 침입 유형을 분석하여 대응 알고리즘을 개발하는 것이 대부분이다. 현재 알려진 침입 탐지 기법은 비정상 탐지(Anomaly Detection)와 오용 탐지(Misuse Detection)로 분류할 수 있는데, 전자는 통계적 방법, 특징 추출 등을 이용하며, 후자는 조건부 화률, 전문가 시스템, 상태 전이 분석, 패턴 매칭 둥을 적용한다. 본 연구에서는 상태전이 기반의 연관 마이닝 기법을 이용한 침입 시나리오 탐지 알고리즘을 제안한다. 이를 위해 본 연구에서는 의사결정지원시스템에서 많이 적용한 연관 마이닝 기법을 여러 가지 불법 침입과 연관된 상태 정보를 분석할 수 있는 수정된 상태전이 알고리즘을 제시한다.

• The Korean Journal of Applied Statistics
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• v.27 no.2
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• pp.263-275
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• 2014

The present study used a hierarchical Bayesian approach was used to develop a mixed effect model to describe the transitional behavior of subjects in time nonhomogeneous Markov chains. The posterior distributions of model parameters were not in analytically tractable forms; subsequently, a Gibbs sampling method was used to draw samples from full conditional posterior distributions. The proposed model was implemented with real data.

• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.126-126
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• 2017

수도권 광역상수도는 관로 매설 이후 30년 이상 경과하여 수도관로 사고 발생빈도가 증가하고 있다. 이에 노후관로를 갱생하여 사고예방과 용수공급 안정성 강화를 도모할 필요가 있으며, 이러한 사업의 수행 여부에 대한 판단을 위해서는 사업 시행으로 발생하는 경제적 편익에 대한 정량적 정보가 필요하다. 노후관로 갱생사업의 경제적 편익은 크게 관로사고 피해저감 편익과 복구비용 절감편익으로 구분되는데 후자는 공학적 접근을 통해 비교적 쉽게 평가할 수 있는 반면에, 전자는 평가가 어렵다. 이에 본 논문에서는 조건부 가치측정법이라는 경제학적 기법을 적용하여 관로사고 피해저감 편익을 추정하고자 한다. 수도권 광역상수도 갱생사업의 수혜지역 주민 600 가구를 무작위로 추출하여 수도권 광역상수도 갱생사업이 시행되지 않을 경우 관로사고가 발생할 수 있음을 설명한 후, 관로사고를 막기 위한 지불의사액을 조사하였다. 분석결과 관로사고 피해 회피를 위한 가구평균 지불의사액은 톤당 약 41.7원이었다. 이 정보는 노후관로 갱생사업에 대한 의사 결정시 활용할 수 있다.

• Journal of Korea Water Resources Association
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• v.44 no.2
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• pp.125-134
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• 2011

The paper is to estimate willingness-to-pay (WTP) for residential water quality improvement in Busan, using non-parametric approach. There are several significant advantages of non-parametric approach, compared to parametric methods. That is, no probability distribution assumption is necessary so that there are no needs to assume or test goodness of fit, model specification and heteroscedasticity statistically. For the reliability and the validity of contingent valuation method a survey was conducted for 665 respondents, who were sampled by stratified random sampling method, by personal interview method. The result of mean WTP for residential water quality improvement in Busan was estimated to be 3,190 won to 3,331 won per month per household, while median WTP being 1,750 won. Provided that our sample is broadly representative of the Busan's population, an estimate of the annual aggregated benefit of residential water improvement for all Busan households is approximately 50.2 billion won in case of mean WTP or 27.5 billion won in case of median WTP.

• Journal of the Korean earth science society
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• v.31 no.4
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• pp.301-312
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• 2010

Geochemical data have been regarded as one of the important environmental variables in the environmental management. Since they are often sampled at sparse locations, it is important not only to predict attribute values at unsampled locations, but also to assess the uncertainty attached to the prediction for further analysis. The main objective of this paper is to exemplify how indicator geostatistics can be effectively applied to geochemical data processing for providing decision-supporting information as well as spatial distribution of the geochemical data. A whole geostatistical analysis framework, which includes probabilistic uncertainty modeling, classification and risk analysis, was illustrated through a case study of cadmium mapping. A conditional cumulative distribution function (ccdf) was first modeled by indicator kriging, and then e-type estimates and conditional variance were computed for spatial distribution of cadmium and quantitative uncertainty measures, respectively. Two different classification criteria such as a probability thresholding and an attribute thresholding were applied to delineate contaminated and safe areas. Finally, additional sampling locations were extracted from the coefficient of variation that accounts for both the conditional variance and the difference between attribute values and thresholding values. It is suggested that the indicator geostatistical framework illustrated in this study be a useful tool for analyzing any environmental variables including geochemical data for decision-making in the presence of uncertainty.

• Environmental and Resource Economics Review
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• v.19 no.1
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• pp.101-127
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• 2010

The purpose of the research is to tackle proximity effects (PEs) when nonmarket valuation method CVM is applied to environmental goods such as tidal flats. 1,000 households are surveyed in the ratio of national household for the research. The sample are reclassified into five areas by 30-minute distance. Log-linear are used to analysis PEs in the research. On conclusion log-linear model regarding income effects proves that PEs are apparently represented in NMVMs(${\theta}_1$ >0. ${\theta}_2$ >0 and $dum1{\neq}0$, $dum2{\neq}0$, $dum3{\neq}0$, $dum4{\neq}0$) as a result of a 5 per cent significant level of t -test and F-test, finally rejecting the null hypothesis. In addition, WTP of area I respondents shows 26 per cent more then that of area V respondents, which is from \87,969 to \64,866 in the open-ended format. Finally, the research proves that the PEs in CVM are evidently represented with the econometric model, hence the PEs have to be embedded into the questionnaire of non-market valuation methods with the environmental goods to reduce the underestimation and improve the estimation accuracy.

• Journal of the Korean Society of Marine Environment & Safety
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• v.19 no.5
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• pp.417-429
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• 2013

The current study attempted to assess the environmental value of Geum-river estuary for rational management decision-making. To investigate the comprehensive properties of the Geum-river estuary, we applied the contingent valuation method based on multi-attribute utility theory. We surveyed a randomly selected sample of 400 and 600 households of the Geum-river estuary-neighboring area (Jeollabuk-do, Chungcheongnam-do), and other nation-wide large districts (except Jeollabuk-do, Chungcheongnam-do, and Jeju-do), respectively, and carried out person-to-person interviews with subjects on their willingness-to-pay for the estuary conservation and management program. Respondents, overall, accepted the contingent market system and were willing to contribute a significant amount, that is 1,497 won for the residents from the Geum-river estuary-neighboring area and 4,343 won for the residents from other nation-wide large districts on average, per household per year. These results implied that there were large difference between the two groups. The aggregate values of the Geum-river estuary for the estuary-neighboring area and other nation-wide large districts amount to 2.13 and 70.15 billion won, respectively, per year. This quantitative value deduced from the current study, could be a useful baseline fact for any decision-making process particularly in the establishment of management policies for the Geum-river estuary.

• Journal of Environmental Policy
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• v.6 no.2
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• pp.1-25
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• 2007

This paper attempts to measure the environmental value of the Seomjin-River estuary that has been comparatively well conserved but is confronted with the threat of its development. Especially, in order to elicit the environmental values of its four attributes, contingent valuation method(CVM) based on multi-attribute utility theory is applied and the CVM survey was rigorously designed to comply with the guidelines. for best-practiced CVM studies. We surveyed a randomly selected sample of 300 and 350 households in the Seomjin-River estuary-neighboring area(Gwangyang, Sooncheon, Yeosu, Hadong, Namhae) and seven large cities(Seoul, Busan, Incheon, Daegu, Daejeon, Gwangju, Ulsan), respectively and asked respondents questions in person-to-person interviews about what they would willing to pay for the estuary conservation and management program. Respondents overall accepted the contingent market and were willing to contribute a significant amount(5,763 won in the Seomjin-River estuary-neighboring area and 1,883 won in seven large cities), on average, per household per year, which implies that there is a large difference between the two. The aggregate values of the Seomjin-River estuary in the estuary-neighboring area and seven large cities amount to 1.52 and 14.05 billion won, respectively, per year. The quantitative values can be utilized in planning and decision-making about development versus conservation of the estuary.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.42 no.6
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• pp.75-82
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• 2005

The robust feature vector selection method for the multiple frontal face detection is proposed in this paper. The proposed feature vector for the training and classification are integrated by means, amplitude projections, and its 1D Harr wavelet of the input image. And the statistical modeling is performed both for face and nonface classes. Finally, the estimated probability density functions (PDFs) are applied for the detection of multiple frontal faces in the still image. The proposed method can handle multiple faces, partially occluded faces, and slightly posed-angle faces. And also the proposed method is very effective for low quality face images. Experimental results show that detection rate of the propose method is $98.3\%$ with three false detections on the testing data, SET3 which have 227 faces in 80 images.