• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2003년도 Proceedings of the international symposium on the fusion technology
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• pp.352-361
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• 2003

We have evaluated the extent of saltwater intrusion from electrical resistivity distribution in a coastal aquifer system in the southeastern part of Busan, Korea. This aquifer system is divided into four layers according to the hydrogeologic characteristics and the horizontal extent of intruded saltwater is determined at each layer through the geostatistical interpretation of electrical resistivity data. In order to define the statistical structure of electrical resistivity data, variogram analysis is carried out to obtain best generalized covariance models. IRF-k (intrinsic random function of order k) kriging is performed with covariance models to produce the plane of spatial mean resistivities. The kriged estimates are evaluated by cross validation to show a good agreement with the true values and the statistics of cross validation represented low errors for the estimates. In the resistivity contour maps more than 5 m below the surface, we can see a dominant direction of saltwater intrusion beginning from the east side. The area of saltwater intrusion increases with depth. The northeast side has low resistivities less than 5 ohm-m due to the presence of saline water in the depth range of 20 m through 70 m. These results show that the application of geostatistical technique to electrical resistivity data is useful for assessing saltwater intrusion in a coastal aquifer system.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권3호
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• pp.1205-1223
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• 2018

Image enhancement is an emerging method for analyzing the images clearer for interpretation and analysis in the spatial domain. The goal of image enhancement is to serve an input image so that the resultant image is more suited to the particular application. In this paper, a novel method is proposed based on Mamdani fuzzy inference system (FIS) using multiple fuzzy membership functions. It is observed that the shape of membership function while converting the input image into the fuzzy domain is the essential important selection. Then, a set of fuzzy If-Then rule base in fuzzy domain gives the best result in image contrast enhancement. Based on a different combination of membership function shapes, a best predictive solution can be determined which can be suitable for different types of the input image as per application requirements. Our result analysis shows that the quality attributes such as PSNR, Index of Fuzziness (IOF) parameters give different performances with a selection of numbers and different sized membership function in the fuzzy domain. To get more insight, an optimization algorithm is proposed to identify the best combination of the fuzzy membership function for best image contrast enhancement.

• 대한교통학회:학술대회논문집
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• 대한교통학회 1995년도 제27회 학술발표회
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• pp.35-56
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• 1995

이 글에서는 공항 여객터미날에 대한 계획 및 운영관리의 실행기준을 인지-반응모델을 이용하여 결정하는 방법을 논의하고자한다. 제시된 접근방법은 서비스의 폭을 승객의 입장에 따라 결정.분류하는 방법이다. 이것은 새로운 개념으로서 공항시스템의 특성을 고려하여 이용승객에 대한 직접적인 조사를 통해 각 시설별 수용능력 및 서비스 수준을 가늠할 수 있도록 도와준다. 이 접근방법에서는 이용자들의 서비스 기대치와 실질적인 서비스 제공에 따른 인식과의 차이를 통해 기준을 설정하는 것으로서 공항 계획자, 디자이너, 운영자 그리고 공항관리자들에게 실질적이고 용이한 기법으로 제공될 수 있다.

• 한국지구과학회지
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• 제23권1호
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• pp.15-29
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• 2002

Bayesian inversion for gravity and resistivity data was performed to investigate the cavity structure appearing as a lava tunnel in Cheju Island, Korea. Dipole-dipole DC resistivity data were proposed for a prior information of gravity data and we applied the geostatistical techniques such as kriging and simulation algorithms to provide a prior model information and covariance matrix in data domain. The inverted resistivity section gave the indicator variogram modeling for each threshold and it provided spatial uncertainty to give a prior PDF by sequential indicator simulations. We also presented a more objective way to make data covariance matrix that reflects the state of the achieved field data by geostatistical technique, cross-validation. Then Gaussian approximation was adopted for the inference of characteristics of the marginal distributions of model parameters and Broyden update for simple calculation of sensitivity matrix and SVD was applied. Generally cavity investigation by geophysical exploration is difficult and success is hard to be achieved. However, this exotic multiple interpretations showed remarkable improvement and stability for interpretation when compared to data-fit alone results, and suggested the possibility of diverse application for Bayesian inversion in geophysical inverse problem.

• Smart Structures and Systems
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• 제3권4호
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• pp.423-437
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• 2007

The empirical mode decomposition (EMD) method is well-known for its ability to decompose a multi-component signal into a set of intrinsic mode functions (IMFs). The method uses a sifting process in which local extrema of a signal are identified and followed by a spline fitting approximation for decomposition. This method provides an effective and robust approach for decomposing nonlinear and non-stationary signals. On the other hand, the IMF components do not automatically guarantee a well-defined physical meaning hence it is necessary to validate the IMF components carefully prior to any further processing and interpretation. In this paper, an attempt to use the EMD method to identify properties of nonlinear elastic multi-degree-of-freedom structures is explored. It is first shown that the IMF components of the displacement and velocity responses of a nonlinear elastic structure are numerically close to the nonlinear normal mode (NNM) responses obtained from two-dimensional invariant manifolds. The IMF components can then be used in the context of the NNM method to estimate the properties of the nonlinear elastic structure. A two-degree-of-freedom shear-beam building model is used as an example to illustrate the proposed technique. Numerical results show that combining the EMD and the NNM method provides a possible means for obtaining nonlinear properties in a structure.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2007년도 Proceedings of ISRS 2007
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• pp.576-579
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• 2007

Timber inventory is a good starting point for developing strategies to effectively manage the timberland. In the sale of timberland, pricing is mostly based on this inventory. For a small timberland, inventory by conventional ground survey could be possible. In the case of large and nationwide business transactions, swift and inexpensive inventory is worth to be considered as the conventional methods require more experienced man power, money and time. In the present study, it was aimed to identify the chronicle of timberland such as changes that has occurred owing to silvicultural activities and by other means using the historical aerial photography and satellite data. Historical aerial photos from National Aerial Photography Program (NAPP), National High Altitude Photography (NHAP), Survey Photography and Landsat satellite data were used. Orthophotos were constructed using the DOQQ and DEM from USGS. Simple photo interpretation technique was employed to classify the orthophoto and satellite data. The plantation area was classified into softwood, mixed and hardwood. The timber age and the corresponding acreage details and the changes were also estimated. The result of this study could be more useful to the timberland buyers to better understand the chronicle of timberland of their interest prior to transactions.

• 대한안전경영과학회지
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• 제15권2호
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• pp.9-20
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• 2013

OSHA(Occupational Safety and Health Act) generally regulates employer's business principles in the workplace to maintain safety environment. This act has the fundamental purpose to protect employee's safety and health in the workplace by reducing industrial accidents. Authors tried to investigate the correlation between 'occupational injuries and illnesses' and level of regulation compliance using Survey on Current Status of Occupational Safety & Health data by the various statistical methods, such as generalized regression analysis, logistic regression analysis and poison regression analysis in order to compare the results of those methods. The results have shown that the significant affecting compliance factors were different among those statistical methods. This means that specific interpretation should be considered based on each statistical method. In the future, relevant statistical technique will be developed considering the distribution type of occupational injuries.

• Advances in aircraft and spacecraft science
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• 제7권6호
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• pp.495-516
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• 2020

Nonlinear state estimation is a desirable and required technique for many situations in engineering (e.g., aircraft/spacecraft tracking, space situational awareness, collision warning, radar tracking, etc.). Due to high standards on performance in these applications, in the last few decades, there was an increasing demand for methods that are able to provide more accurate results. However, because of the mathematical complexity introduced by the nonlinearities of the models, the nonlinear state estimation uses techniques that, in practice, are not so well-established which, leads to sub-optimal results. It is important to take into account that each method will have advantages and limitations when facing specific environments. The main objective of this paper is to provide a comprehensive overview and interpretation of the most well-known methods for nonlinear state estimation with Gaussian priors. In particular, the Kalman filtering methods: EKF (Extended Kalman Filter), UKF (Unscented Kalman Filter), CKF (Cubature Kalman Filter) and EnKF (Ensemble Kalman Filter) with an aerospace perspective.

• 자원환경지질
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• 제16권4호
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• pp.269-276
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• 1983

단순한 사각주형(四角柱型) 물체(物體)에 대한 3차원 표준곡선을 해석하였다. 이들 표준곡선은 쌍극자배치(雙極子配置)에 대하여 적분방정식을(積分方程式) 이용한 수치계산기술(數値計算技術)로 구하였다. 전도성(電導性) 물체에 대한 IP응답(應答)은 물체의 폭과 두께의 비율에 따라서 그 패턴이 달라진다. 주향(走向)길이가 쌍극자간격(雙極子間隔)의 6배 이상이 되면 2차원의 결과와 유사하다. 또한 주향(走向)길이가 길고, 폭이 쌍극자 간격의 4배이상이 되면 층구조(層構造)(1차원) 해석도 가능하게 된다. 한편, 측선(測線)이 주향방향(走向方向)을 따라서 물체의 중심으로부터 멀어지는 효과는 물체의 깊이가 지표로부터 깊어질 때와 비슷하게 나타난다. 물체가 측선하(測線下)에서 측선과 평행(平行)한 방향으로 이동하더라도 IP패턴에는 거의 영향을 미치지 않는다.

• 한국측량학회지
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• 제17권4호
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• pp.383-391
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• 1999

본 논문은 GIS를 사용하여 1998년도 전국의 벼 병해충을 분석하고, 처리된 자료를 인터넷을 통해 정보를 공유 및 분석하는 인터넷 GIS 시스템의 개발에 관한 것이다. 인터넷 GIS는 컴퓨터 네트워크의 광범위한 활용성에 의해 인터넷 환경에서 GIS의 기능을 구현하는 시스템으로서, 본 연구에서는 대화식 인터페이스로 구성된 인터넷 GIS를 개발함으로써 클라이언트들이 기존의 정적인 지도와 양적인 통계 값의 벼 병해충 자료대신에 인터넷상에서 시각적이고 동적인 정보를 제공받을 수 있는 효율적인 방안을 제시하였다.