• Journal of the Institute of Electronics Engineers of Korea SP
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• v.41 no.4
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• pp.31-37
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• 2004

Wavelet transform is a useful tool for analysis and process of image. This showed good performance in image compression and noise reduction. Wavelet coefficients can be effectively modeled by hidden Markov tree(HMT) model. However, in application of HMT model to image interpolation, training procedure is needed. Moreover, the parameters obtained from training procedure do not match input image well. In this paper, the structure of HMT is used for image interpolation, and the parameters of HMT are obtained from statistical characteristics across wavelet subbands without training procedure. In the proposed method, wavelet coefficient is modeled as Gaussian mixture model(GMM). In GMM, state transition probabilities are determined from statistical transition characteristic of coefficient across subbands, and the variance of each state is estimated using the property of exponential decay of wavelet coefficient. In simulation, the proposed method shows improvement of performance compared with conventional bicubic method and the method using HMT model with training.

• 한국지구물리탐사학회:학술대회논문집
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• 2003.11a
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• pp.390-397
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• 2003

A three-dimensional (3D) inversion technique has been developed for interpretation of magnetotelluric (MT) data. The inversion method is based on the linearized least-squares (Gauss-Newton) method with smoothness regularization. In addition to the underground 3D resistivity distribution, static shifts are also treated as unknown parameters in the inversion. The forward modeling is by the staggered-grid finite difference method. A Bayesian criterion ABle is applied to search the optimum trade-off among the minimization of the data misfit, model roughness and static shifts. The method has been applied to several MT datasets obtained at geothermal fields in Japan and other Asian countries. In this paper, two examples will be discussed: one is the data at the Ogiri geothermal area, southwestern Japan, and the other is at the Pohang low-enthalpy geothermal field, southeastern Korea. The inversion of the Ogiri data has been performed stably, resulting in a good fitting between the observed and computed apparent resistivities and phases. The recovered 3D resistivity structure is generally similar to the two-dimensional (2D) inversion models, although the deeper portion of the 3D model seems to be more realistic than that of the 2D model. The 3D model is also in a good agreement with the geological model of the geothermal reservoirs. 3D interpretation of the Pohang MT data is still preliminary. Although the fitting to the observed data is very good, the preliminary 3D model is not reliable enough because the station coverage is not sufficient for a 3D inversion.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.1
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• pp.24-31
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• 2006

In the present study, a strongly coupled analysis code is developed for transonic flutter analysis. For aerodynamic analysis, two dimensional Reynolds-Averaged Navier-Stokes equation was used for governing equation, and ε-SST for turbulence model, DP-SGS(Data Parallel Symmetric Gauss Seidel) Algorithm for parallelization algorithm. 2 degree-of-freedom pitch and plunge model was used for structural analysis. To obtain flutter response in the time domain, dual time stepping method was applied to both flow and structure solver. Strongly coupled method was implemented by successive iteration of fluid-structure interaction in pseudo time step. Computed results show flutter speed boundaries and limit cycle oscillation phenomena in addition to typical flutter responses - damped, divergent and neutral responses. It is also found that the accuracy of transonic flutter analysis is strongly dependent on the methodology of fluid-structure interaction as well as on the choice of turbulence model.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.4A
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• pp.677-687
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• 2006

Kriging interpolation is one of the generally used interpolation techniques in Geostatistics field. This technique includes the experimental and theoretical variograms and the formulation of kriging interpolation. In contrast to the conventional least square method for stress recovery, kriging interpolation is based on the weighted least square method to obtain the estimated exact solution from the stress data at the Gauss points. The weight factor is determined by variogram modeling for interpolation of stress data apart from the conventional interpolation methods that use an equal weight factor. In addition to this, the p-level is increased non-uniformly or selectively through a posteriori error estimation based on SPR (superconvergent patch recovery) technique, proposed by Zienkiewicz and Zhu, by auto mesh p-refinement. The cut-out plate problem under tension has been tested to validate this approach. It also provides validity of kriging interpolation through comparing to existing least square method.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.7 no.1
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• pp.11-22
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• 1987

A plane buoyant jet discharged vertically upward into a crossflow is analyzed by numerical solution of the governing equations of continuity, momentum and constituent transport. The turbulent transport is modelled by the Prandtl's mixing length theory. In the numerical solution procedure, the governing equations are transformed by stream function and vorticity transport, non-dimensionalyzed by discharge velocity, slot width, and parameters representing flow characteristics, and solved by Gauss-Seidel iteration method with successive underrelaxation. The numerical experiments were performed for the region of established flow of buoyant jet in the range of discharge densimetric Froude number of 4 to 32 and in the range of velocity ratio of 8 to 15, which is the ratio of discharge velocity to crossflow velocity. Variations of velocities and temperatures, flow patterns and vorticity patterns of receiving water due to buoyant jet were investigated. Also investigated are the effects of velocity ratio and discharge densimetric Froude number on the trajectories of buoyant jet. Computed are velocities, temperatures and local densimetric Froude numbers along the trajectory of the buoyant jet. Spreading rate and dispersion ratio were analyzed in terms of discharge densimetric Froude number, local densimetric Froude number and distance from the source along the jet trajectory. It was noted that the similarity law holds in both the profiles of velocity and temperatures across the jet trajectory and the integral type analysis of Gaussian distribution is applicable.

• Journal of Korean Tunnelling and Underground Space Association
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• v.16 no.2
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• pp.149-160
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• 2014

The objective of this study is the application of the harmony search (HS) algorithm and verification of the accuracy of inverse analysis to predict the location, thickness and electrical properties of anomalous zone ahead of tunnel face when utilizing the electrical resistivity survey using electrical resistivity of the ground. The relationship correlating the characteristic values of the anomalous zone with the electrical resistance values was derived using Gauss' laws and Ohm's laws. Inverse analysis program was developed to predict anomalous zone by using electrical resistivity based on HS algorithm. Electrical resistance measuring system is devised to obtain the electrical resistivity of the ground, and laboratory tests were performed on anomalies to verify the proposed HS algorithm. The test results show that the characteristics of the anomalies are predicted reasonably well resulting in less than 5% error when predicting the location and thickness of the anomaly.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.11 no.3
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• pp.179-196
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• 1986

In this paper, the peformance of a statistical packet voice/data multiplexer is studied. In ths study we assume that in the packet voice/data multiplexer two separate finite queues are used for voice and data traffics, and that voice traffic gets priority over data. For the performance analysis we divide the output link of the multiplexer into a sequence of time slots. The voice signal is modeled as an (M+1) - state Markov process, M being the packet generation period in slots. As for the data traffic, it is modeled by a simple Poisson process. In our discrete time domain analysis, the queueing behavior of voice traffic is little affected by the data traffic since voice signal has priority over data. Therefore, we first analyze the queueing behavior of voice traffic, and then using the result, we study the queueing behavior of data traffic. For the packet voice multiplexer, both inpur state and voice buffer occupancy are formulated by a two-dimensional Markov chain. For the integrated voice/data multiplexer we use a three-dimensional Markov chain that represents the input voice state and the buffer occupancies of voice and data. With these models, the numerical results for the performance have been obtained by the Gauss-Seidel iteration method. The analytical results have been verified by computer simylation. From the results we have found that there exist tradeoffs among the number of voice users, output link capacity, voic queue size and overflow probability for the voice traffic, and also exist tradeoffs among traffic load, data queue size and oveflow probability for the data traffic. Also, there exists a tradeoff between the performance of voice and data traffics for given inpur traffics and link capacity. In addition, it has been found that the average queueing delay of data traffic is longer than the maximum buffer size, when the gain of time assignment speech interpolation(TASI) is more than two and the number of voice users is small.

• The Journal of Korean Academy of Prosthodontics
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• v.43 no.4
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• pp.511-518
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• 2005

Purpose: The purpose of this study is to find the effect of rare earth magnet's magnetic field of to the osteoblast around the implant by the means of observation number, and distribution around the implant which is connected to the permanent magnet but not, counted and compared by the number of cells attached to the surface of the implant. Material and method: The permanent magnets, made in the healing cap form, were connected to the implant future, and placed on the culture plate, The osteoblast-like cell: MC3T3-E1 were used for cell culture. As the control group, the implant were connected to normal healing cap, and cultured in the same conditions. 48 hours later, using inverted microscope, the number and distribution of osteoblast around the implant were observed, and 72 hours later, the number of the cells attached to the implant were counted. Results: As a result, the implant connected to the permanent magnet had proved to have a more concentrated cell distribution rate than the control group. The implant connected to the permanent magnet, neck area : which has about 10 gauss magnetic force, had more cells than apex area. The implant connected to the permanent magnet had proven to attach to the osteoblast more productively than control group's implant. Conclusions: This research showed that the magnetic field of the permanent magnet affected the distribution and growth rate of the osteoblast around the implant. In order to support this study, it also had need to monitor the progress of the permanent magnet specifically shown on the neck area, which has10 gauss magnetic force. So after additional research on the distribution and attachment of the cells, and further more, on bone formation, it will be concluded that the clinical applications ,such as immediate loading of implant treatment are possible.

• Geotechnical Engineering
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• v.8 no.2
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• pp.5-20
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• 1992

The physical-based and lumped-parameter hydrologic groundwater flow model for predicting the rainfall-triggered rise of groundwater levels in hillside slopes is developed in this paper to assess the risk of landslides. The developed model consists of a vertical infiltration model for unsaturated zone linked to a linear storage reservoir model(LSRM) for saturated zone. The groundwater flow model has uncertain constants like soil depttL slope angle, saturated permeability, and potential evapotranspiration and four free model parameters like a, b, c, and K. The free model parameters could be estimated from known input-output records. The BARD algorithm is uses as the parameter estimation technique which is based on a linearization of the proposed model by Gauss -Newton method and Taylor series expansion. The application to examine the capacity of prediction shows that the developed model has a potential of use in forecast systems of predicting landslides and that the optimal estimate of potential 'a' in infiltration model is the most important in the global optimum analysis because small variation of it results in the large change of the objective function, the sum of squares of deviations of the observed and computed groundwater levels. 본 논문에서는 가파른 산사면에서 산사태의 발생을 예측하기 위한 수문학적 인 지하수 흐름 모델을 개발하였다. 이 모델은 물리적인 개념에 기본하였으며, Lumped-parameter를 이용하였다. 개발된 지하수 흐름 모델은 두 모델을 조합하여 구성되어 있으며, 비포화대 흐름을 위해서는 수정된 abcd 모델을, 포화대 흐름에 대해서는 시간 지체 효과를 고려할 수 있는 선형 저수지 모델을 이용하였다. 지하수 흐름 모델은 토층의 두께, 산사면의 경사각, 포화투수계수, 잠재 증발산 량과 같은 불확실한 상수들과 a, b, c, 그리고 K와 같은 자유모델변수들을 가진다. 자유모델변수들은 유입-유출 자료들로부터 평가할 수 있으며, 이를 위해서 본 논문에서는 Gauss-Newton 방법을 이용한 Bard 알고리즘을 사용하였다. 서울 구로구 시흥동 산사태 발생 지역의 산사면에 대하여 개발된 모델을 적용하여 예제 해석을 수행함으로써, 지하수 흐름 모델이 산사태 발생 예측을 위하여 이용할 수 있음을 입증하였다. 또한, 매개변수분석 연구를 통하여, 변수 a값은 작은 변화에 대하여 목적함수값에 큰 변화를 일으키므로 a의 값에 대한 최적값을 구하는 것이 가장 중요한 요소라는 결론을 얻었다.

• Journal of Astronomy and Space Sciences
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• v.31 no.1
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• pp.63-66
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• 2014

Since Rigollet first discovered a comet in 1939, many follow-up observations have been made, particularly in Europe. It is now known that the Rigollet comet is identical with the one observed by Herschel in 1788, and thus it is now called 35P/1939 O1 or the Herschel-Rigollet comet. Yumi, a Japanese astronomer, also observed the Rigollet comet in Korea using a 6-inch refractor telescope, and published his data in two Japanese journals (Bulletin of the Observatory of the Government-General of Korea and Publication of the Lecture on Meteorology). In his paper, Yumi also referred to observations by Hirose and Kanda in Japan. However, their works have not been given attention by international society. In this study, we analyze the observation data of Yumi and present preliminary orbital elements using it with a modified Gauss method. We expect that this study will be used to refine the orbital elements of the Rigollet comet by orbital-calculation experts. For that reason, we have also transcribed all the observational data presented by Yumi.