• Journal of Korea Water Resources Association
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• v.49 no.4
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• pp.315-325
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• 2016

Generally, a natural river discharge is highly regulated by the hydraulic structures, and the regulated flow is substantially different from natural inflow characteristics for the use of water resources planning. The natural inflow data are necessarily required for hydrologic analysis and water resources planning. This study aimed to develop an integrated model for more reliable simulation of daily dam inflow. First, a piecewise Kernel-Pareto distribution was used for rainfall simulation model, which can more effectively reproduce the low order moments (e.g. mean and median) as well as the extremes. Second, a Bayesian Markov Chain Monte Carlo scheme was applied for the SAC-SMA rainfall-runoff model that is able to quantitatively assess uncertainties associated with model parameters. It was confirmed that the proposed modeling scheme is capable of reproducing the underlying statistical properties of discharge, and can be further used to provide a set of plausible scenarios for water budget analysis in water resources planning.

• Journal of Ocean Engineering and Technology
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• v.28 no.2
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• pp.93-101
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• 2014

In general, particle simulation methods such as the MPS(Moving Particle Simulation) or SPH(Smoothed Particle Hydrodynamics) methods have some serious drawbacks for pressure solutions. The pressure field shows spurious high fluctuations both temporally and spatially. It is well known that pressure fluctuation primarily occurs because of the numerical approximation of the partial differential operators. The MPS and SPH methods employ a pre-defined kernel function in the approximation of the gradient and Laplacian operators. Because this kernel function is constructed artificially, an accurate solution cannot be guaranteed, especially when the distribution of particles is irregular. In this paper, we propose a particle simulation method based on the moving least-square technique for solving the partial differential operators using a Taylor-series expansion. The developed method was applied to the hydro-static pressure and dam-broken problems to validate it.

• Journal of the Korean Wood Science and Technology
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• v.38 no.6
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• pp.498-506
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• 2010

To use domestic softwood for structural lumber, appropriate grading system for quality, production and distribution condition of domestic lumber should be prepared. Kim et al. developed an automatic image processing system for grading domestic structural lumber (2009a and b). This study was carried out to investigate optimal image merging conditions for improving performance of image input system which is the key technique of image processing system, developed in the previous paper. To merge digital images of Korean larch lumber, choosing the green channel information of obtained image data showed the most accurate merging performance. As a pre-treatment process, applying Y-derivative Sharr's kernel filter could improve the image merging accuracy, but the effect of camera calibration was imperceptible. The optimal size of template image was verified as 30 pixel widths and 150 pixel heights. When applying the above mentioned conditions, the error length of images was 3.1 mm and the processing time was 9.7 seconds in average.

• Progress in Medical Physics
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• v.7 no.1
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• pp.9-17
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• 1996

The response function of ionization chambers are measured in the narrow radiation field Nominal photon energies are 4MV, 6MV and 15MV. the Radii of the chambers are 0.5cm～3.05cm and the field size is 0.2$\times$20$\textrm{cm}^2$. The measurements are taken in the water phantom at 10cm depth. The beam kernel (radiation distribution profile) for narrow radiation field in the phantom are obtained from Monte Carlo simulation (EGS4, Electron Gamma Shower 4). The beam kernel components in the measured chamber response function are deconvolved in order to get the ideal chamber response function of the $\delta$-shaped function radiation field. The chamber response functions have energy dependent tendency before deconvolution, while they show energy invariant properties, after the components of beam kernels are removed by deconvolution method.

• Journal of Radiation Protection and Research
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• v.10 no.2
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• pp.155-159
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• 1985

In general, dose rates for a monoenergetic gamma emitter uniformly distributed in an infinite cloud have been calulated by using the monoenergetic point-isotorpic source kernel technique. The most serious limitation on use of the kernel technique is subjected to the fact that it estimates the dose only at the surface of body. As a result, an alternative method is presented in which estimates of dose rate for immersion in a radioactive cloud are resulted from the scattered photon spectra incident on the surface of body. The results are in excellent agreement with other's. Work is currently in progress to apply these results to immersion dose problems associated with absorbed dose distribution in the MIRD phatom.

• Korean Journal of Food Science and Technology
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• v.34 no.4
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• pp.597-603
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• 2002

The analysis of traditional process for a Korean puffed rice snack (Yukwa) is needed to develop an advanced process for Yukwa-making. Steeping and punching (Koarichigi) processes, consume time and labor in Yukwa-making, were analyzed on this study. Steeping of waxy rice at $15^{\circ}C$ for 3 days was required to equilibrate moisture absorption in waxy rice kernel. However, steeping for more than 6 days was required soft texture and small air cell distribution of Yukwa. Protein content at pericarp on endosperm of waxy rice kernel was decreased and starch granule was damaged during steeping. RVA paste viscosity was the highest at 6 day steeping after than decreased. Expansion ratio of Yukwa was increased with the increase in steeping time. Air bubbles in dough after punching were uniformly distributed and kneading energy input was decreased with the increase in steeping time. Soft texture, unique texture of Yukwa could be controlled by controlling steeping time and kneading energy input during punching process.

• Journal of Advanced Marine Engineering and Technology
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• v.33 no.2
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• pp.344-354
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• 2009

Side scan sonar using acoustic wave plays a very important role in the underwater, sea floor, and shallow marine geologic survey. In this study, we have acquired side scan sonar data for the underwater man-made structures, artificial reefs and fishing grounds, installed and distributed in the survey area. We applied digital image processing techniques to side scan sonar data in order to improve and enhance an image quality. We carried out digital image processing with various kinds of filtering in spatial domain and frequency domain. We tested filtering parameters such as kernel size, differential operator, and statistical value. We could easily estimate the conditions, distribution and environment of artificial structures through the interpretation of side scan sonar.

• Journal of Mechanical Science and Technology
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• v.17 no.10
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• pp.1399-1410
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• 2003

In this paper, we develop a joystick manual driving algorithm for an electric vehicle called Cycab. Cycab is developed as a public transportation vehicle, which can be driven either by a manual joystick or an automated driving mode. The vehicle uses six motors for driving four wheels, and front/rear steerings. Cycab utilizes one industrial PC with a real time Linux kernel and four Motorola MPC555 micro controllers, and a CAN network for the communication among the five processors. The developed algorithm consists of two automatic vehicle speed control algorithms for normal and emergency situations that override the driver's joystick command and an open loop torque distribution algorithm for the traction motors. In this study, the algorithm is developed using SynDEx, which is a system level CAD software dedicated to rapid prototyping and optimizing the implementation of real-time embedded applications on distributed architectures. The experimental results verify the usefulness of the two automatic vehicle control algorithms.

• Journal of the Korean Statistical Society
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• v.30 no.2
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• pp.231-246
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• 2001

Local linear smoothing enjoys several excellent theoretical and numerical properties, an in a range of applications is the method most frequently chosen for fitting curves to noisy data. Nevertheless, it suffers numerical problems in places where the distribution of design points(often called predictors, or explanatory variables) is spares. In the case of univariate design, several remedies have been proposed for overcoming this problem, of which one involves adding additional ″pseudo″ design points in places where the orignal design points were too widely separated. This approach is particularly well suited to treating sparse bivariate design problem, and in fact attractive, elegant geometric analogues of unvariate imputation and interpolation rules are appropriate for that case. In the present paper we introduce and develop pseudo dta rules for bivariate design, and apply them to real data.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.736-739
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• 1995

The meshless adaptive method based on multiple scale analysis is developed to simulate large deformation problems. In the procedure, new particles are simply added to the orginal particle distribution because meshless methods do not require mesh structures in the formulations. The high scale component of the approximated solution detects the localized region where a refinement is needed. The high scale component of the second invariant od Green-Lagrangian strain tensor is suggested as the new high gradient detector for adaptive procedures. The feasibility of the proposed theory is demonstrated by a numerical experiment for the large deformation of hyperelastic materials.