• Proceedings of the Korea Society for Industrial Systems Conference
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• 1998.03a
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• pp.305-311
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• 1998

본 논문에서는 회전과 크리에 무관한 상관결과를 얻기 위하여 WCHF-fSDF(wavelet circular harmonic function-filter modulation synthetic discriminant function)필터를 제안하였다. WCHF-fSDF 필터는 기준영상에 대하여 크기변화된 영상들을 웨이브릿 변환한 후, 이들로부터 추출한 단일 원형고조함수를 학습영상으로 사용하여 합성한다. 웨이브릿 변환은 입력영상과 웨이브릿 함수와의 상관으로 정의되므로 웨이브릿 변환을 이용한 패턴인식을 하기 위해서는 두 개의 4f 광 상관 시스템이 필요하다. 여기서 입력영상에 필요한 웨이브릿 함수를 제안된 필터의 설계과정에 포함시켜 전체 광 상관 시스템을 하나의 4f 광상관시스템을 대체시켰다.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.319-324
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• 2011

최근 자연환경보전이라는 새로운 패러다임의 대두로 하천의 생태기능 향상을 위한 호안조성공법 중 하나인 식생매트호안 공법의 적용이 증가하고 있다. 국내 하천의 경우 비교적 큰 하상계수와 소류력의 증가로 식생매트 고정용 앵커핀의 기능 저하에 따른 호안의 피해가 발생하고 있다. 그러나 앵커핀의 외력저항성 연구 및 설치를 위한 기준이 마련되어 있지 않는 실정이다. 본 연구에서는 앵커핀의 인발특성을 연구함으로서 외력저항 특성을 파악하고자 하였다. 연구방법으로는 앵커핀을 관입시킨 토사에 인발장치를 연결하여 최대인발력과 인발력의 변화추이를 관찰하였다. 실험에 사용된 토사는 물다짐으로 다졌으며, 앵커핀은 식생매트 고정용으로 적용이 많은 이형철근형 앵커핀을 사용하였다. 대조군으로 형태가 동일한 원형철근을 이용하여 앵커핀을 제작 실험에 사용하였다. 실험조건은 앵커핀의 직경(10mm, 16mm)에 따른 주면과 침수토사의 배수시간 (48hr, 96hr, 144hr) 조절을 통한 함수율의 변화에 따른 인발특성을 관측하였다. 실험결과 평균 최대인발력의 변화는 48시간 배수시 직경변화에 따라 이형철근은 12.8N, 28N, 원형철근은 10.6N, 21N으로 나타났으며, 96시간 배수시 이형철근은 18.8N, 33N, 원형철근은 12.2N, 21.6N으로 나타났고, 144시간 배수시 이형철근은 21.4N, 36.4N, 원형철근은 20.4N, 33.2N으로 나타났다. 앵커핀의 인발력은 주면의 크기에 비례하며, 표면의 형태와 함수량에 따라 영향을 받는 것으로 나타났다. 따라서 이러한 앵커핀의 인발 특성을 파악하고, 식생호안에 적용한다면 피해를 최소화 할 수 있을 것으로 사료된다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.1
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• pp.185-191
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• 2004

This article is concerned with cloth wearing system issues arising in the computer graphics. In particular, we study the issues of fabric drape properties for representing cloth wearing system. The convex points based on distance function are calculated to represent useful fabric drape properties. The information such as perimeter area, max and min point among convex point, the average distance between convex points are extracted. A strategy of a circularity based on the perimeter and area is considered for fabric drape property measurement. By experimental result, the circularity is most powerful factor to represent the drape property among the several characteristics. The measured drape properties will contribute to cloth wearing system development.

• Journal of Korean Association for Spatial Structures
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• v.5 no.4 s.18
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• pp.61-70
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• 2005

In paper the discrete optimum design program was developed using the continuous and discrete optimum algorithms based on the SUMT and genetic algorithms. In this paper, the objective function is the weight of structures and the constraints are limits state design limits method. The design variables are diameter and thick of steel pipe. Design examples are given to show the applicability of the optimum design using the continuous and discrete optimum algorithms based on the SUMT and genetic algorithms of this study.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.12
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• pp.2328-2339
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• 1992

The propagation of coherent time-harmonic elastic L-and SV-waves is studied in a medium with random distribution of cylindrical inclusions. The purpose of the research is to characterize the dynamic elastic moduli and the attenuation properties of fiber-reinforced composite materials. The cylindes representing the fibers are assumed to be distributed in parallel with each other and the direction of incident waves are normal to the cylinder axes. A multiple scattering formula using the single scattering coefficients in conjunction with the Lax's quasicrystalline approximation is derived from which the dispersion relation for such medium is obtained. In order to formulate the multiple scattering interaction between cylinders, the pair correlation functions are generated by the Monte Carlo simulation technique. From the numerically evaluated complex wavenumbers, the propagation speed of the average wave, the coherent attenuation and the effective elastic moduli are presented as functions of frequency and fiber volume fraction.

• Tunnel and Underground Space
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• v.31 no.6
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• pp.480-493
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• 2021

Since the generalized Hoek-Brown criterion (GHB) provides an efficient way of identifying its strength parameter values with the consideration of in-situ rock mass condition via Geological Strength Index (GSI), this criterion is recognized as one of the standard rock mass failure criteria in rock mechanics community. However, the nonlinear form of the GHB criterion makes its mathematical treatment inconvenient and limits the scope of its application. As an effort to overcome this disadvantage of the GHB criterion, the explicit approximate analytical equations for the minimum principal stress, which is associated with the maximum principal stress at failure, are formulated based on the Taylor polynomial approximation of the original GHB criterion. The accuracy of the derived approximate formula for the minimum principal stress is verified by comparing the resulting approximate minimum principal stress with the numerically calculated exact values. To provide an application example of the approximate formulation, the equivalent friction angle and cohesion for the expected plastic zone around a circular tunnel in a GHB rock mass are calculated by incorporating the formula for the approximate minimum principal stress. It is found that the simultaneous consideration of the values of mi, GSI and far-field stress is important for the accurate calculation of equivalent Mohr-Coulomb parameter values of the plastic zone.

• Journal of Korea Society of Industrial Information Systems
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• v.9 no.2
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• pp.81-88
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• 2004

For scale and rotation invariant pattern recognition of images with noise, an optical wavelet CHF-fSDF filter is proposed. Wavelet CHF-fSDF filter is synthesized by each single CHF extracted from scale-changed and wavelet transformed images for a referene image as training images. The proposed optical wavelet CHF-fSDF filter is the type of the matched filter so that it can use the structure of 4f optical correlation system. The results of computer simulation show that the proposed filter has the rotation and scale-invariant correlation output and it is useful in the noisy input.

• Journal of Korea Multimedia Society
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• v.10 no.10
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• pp.1284-1294
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• 2007

In this paper, a blind nonlinear channel equalization is implemented by using a Modified Fuzzy C-Means (MFCM) algorithm. The proposed MFCM searches the optimal channel output states of a nonlinear channel from the received symbols, based on the Bayesian likelihood fitness function instead of a conventional Euclidean distance measure. Next, the desired channel states of a nonlinear channel are constructed with the elements of estimated channel output states, and placed at the center of a Radial Basis Function (RBF) equalizer to reconstruct transmitted symbols. In the simulations, binary signals are generated at random with Gaussian noise. The performance of the proposed method is compared with that of a hybrid genetic algorithm (GA merged with simulated annealing (SA): GASA), and the relatively high accuracy and fast searching speed are achieved.

• Journal of the Korean GEO-environmental Society
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• v.16 no.12
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• pp.23-35
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• 2015

Nonlinear soil behavior before failure under dynamic loading is often implemented in a numerical analysis code by a mathematical fitting function model with Masing's rule. However, the model may show different behavior with an experimental results obtained from laboratory test in damping ratio corresponding secant shear modulus for a certain shear strain rage. The difference may come from an unique soil characteristics which is unable to implement by using the existing mathematical fitting model. As of now, several fitting models have been suggested to overcome the difference between model and real soil behavior but consequence of the difference in dynamic analysis is not reviewed yet. In this paper, the effect of the difference on site response was examined through nonlinear response history analysis. The analysis was verified and calibrated with well defined dynamic geotechnical centrifuge test. Site response analyses were performed with three mathematical fitting function models and compared with the centrifuge test results in prototype scale. The errors on peak ground acceleration between analysis and experiment getting increased as increasing the intensity of the input motion. In practical point of view, the analysis results of accuracy with the fitting model is not significant in low to mid input motion intensity.

• Journal of Wetlands Research
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• v.15 no.3
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• pp.423-430
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• 2013

An algorithm to allow shoreline movement during numerical experiment on sediment transport, deposition or resuspension for general coastal morphology is proposed here. The bed slope near shoreline, i.e. mean sea level, is influenced by bed material, tidal current, waves, and wave-induced current, but has been reported to remain within a stable range. Its annual variation is not large, either. The algorithm is adjusting the bathymetry, if the largest bed slope within shoreline band exceeds a given bed slope due to continuous erosion at zones below the shoreline. This algorithm automatically describes retreat of shoreline caused by erosion, when used within a numerical system. The algorithm was tested to a situation which includes a continuous dredging at a point, and showed satisfactory development of concentric circle contours. Next, the algorithm was tested to another situation which includes sinking of eroded part of bed plate, and produced satisfactory results, too. Finally, the algorithm was tested to a movable-bed laboratory experimental conditions. The shoreline movement behind detached breakwater was reasonably reproduced with this algorithm.