• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.426-429
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• 2001

Many various products are manufactured which have sculptured surfaces recently. Constructing surface of these models is required technique called reverse engineering. In reverse engineering, a product which has sculptured surfaces is measured and we create surface model to acquire complete model data of object. Measured point data needs preprocess and sampling. Next a set of point data in a plane fit section curve. At last, surface is generated by fitting to section curves. Here we uses sweep surface. Sweep surface is compatible fitting CAD model to drawing. This paper discusses converting approximation of NURBS surface as a standard surface.

• Journal of Environmental Health Sciences
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• v.39 no.1
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• pp.56-70
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• 2013

Objectives: This paper aims to investigate the seasonal deposition characteristics of water-soluble ion species by comparing the deposition amount of two samples taken according to different sampling methods of deposition for ambient aerosol such as gases and particulate matters. Methods: Deposition samples were collected using two deposition gauges in the downtown area of Iksan City over approximately two weeks of each season in 2004. The type of deposition gauges consisted of two different sampling methods known as dry gauge and a wet gauge. The dry gauge was empty and used a dry PE bottle with an inlet diameter of 9.6 cm. Before the beginning of each deposition sampling, a volume of 30-50 ml distilled ionized water was added to the wet gauge to wet the bottom during the sampling period. Deposition samples were measured twice per day and analyzed for inorganic water-soluble ion species using ion chromatography. Results: The daily deposition amounts of all measured ions in the dry gauge and the wet gauge showed a significant increase when precipitation occurred, having no difference of deposition amount between in the wet gauge and in the dry gauge. By excluding two samples from rainy days during the sampling period, the mean daily deposition of all ions in dry gauge and wet gauge were $6.58mg/m^2/day$ and $18.16mg/m^2/day$, respectively. The mean deposition amounts of each ion species were higher in the wet gauge than in the dry gauge because of the surface difference of the sampling gauge, especially for $NH_4{^+}$ and ${SO_4}^{2-}$. The mean deposition amounts of $NH_4{^+}$ and ${SO_4}^{2-}$ in the wet gauge were found to be about 15.4 times and 5.2 times higher than that in dry gauge, with a pronounced difference between spring and summer, while the remaining ion species were 1.1-2.0 times higher in the wet gauge than in the dry gauge. Dominant species in the dry gauge were $Ca^{2+}$ and $NO_3{^-}$, accounting for 36.4% and 18.1% of the total ion deposition, whereas those in the wet gauge were $NH_4{^+}$ and ${SO_4}^{2-}$, accounting for 32.5% and 25.0% of the total ion deposition, respectively. Conclusion: The seasonal differences in deposition amounts of water-soluble ion species in ambient aerosol depending on the two types of different sampling methods were identified. This suggests that the removal of ambient aerosol is strongly influenced by the weather conditions of each season as well as the condition of earth's surface, such as dry ground and water.

• Tunnel and Underground Space
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• v.26 no.1
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• pp.46-58
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• 2016

In this study, a LIDAR laser scanner was used to scan a rock slope around Mt. Gwanak and to produce point cloud from which directional information of rock joint surfaces shall be extracted. It was analyzed using two different algorithms, i.e. Ball Pivoting and Wrap algorithm, and four sampling intervals, i.e. raw, 2, 5, and 10 cm. The results of Fuzzy K-mean clustering were analyzed on the stereonet. As a result, the Ball Pivoting and Wrap algorithms were considered suitable for extraction of rock surface orientation. In the case of 5 cm sampling interval, both triangulation algorithms extracted the most number of the patch and patched area.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1996.04a
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• pp.100-103
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• 1996

Presented in this study is an algorithmic procedure to obtain polyhedral model from a compound surface. The compound surface in this study denotes a collection of trimmed surfaces without topological relations. The procedure consists of two main modules: CAD data interface, and surface conversion to polyhedral model. The interface module gets geometric information from CAD databases, and makes topological information by scanning the geometric information. We are investigating CATIA system as a data source system. In the surface conversion module, a shell(compound surface with topological information) is approximated to a triangular-faceted polyhedral surface model through node sampling and triangulation steps. The obtained polyhedral model should obey the vertex-to-vertex rule and meet tolerance requirements. Since the polyhedral model has a simple data structure and geometry processing for it is very efficient and robust, the polyhedral model can be used in various applications, such as surface rendering in computer graphics, FEM model for engineering analysis, CAPP for surface machining, data generation for SLA, and NC tool path generation.

• 한국해양학회지
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• v.12 no.2
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• pp.75-81
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• 1977

Distribution of drifting larvae of Anadara broughtnoii SCHRENCK was studied based on the planktonic sampling which has been collected in fifteen sampling areas of southern coast of Korea and Ulsan Bay during summer season from 1973 to 1977. Vertical and horizontal occurrence was analyzed related to the environmental factors such as surface water temperature, current velocity and depth of water column. High density of the larvae was observed in the Chinhae Bay which included the sampling areas Rampo, Sockcheon, Majeon, Changpo, Dangdong, Bedun, Changchoa, and Wonmun. Maximum occurrence of the farvae was accompanied with the highest water temperature of the summer season, and it was usually August when the water temperature was over 27$^{\circ}C$. In August, 1975, the highest density of the farvae was observed, when the mean surface water temperature was the highest compared to those of other years. The first appearence of the drifting larvae was also related to the surface water temperature. Each year the larae begin to appear from the late July and the ready-to-fall larvae appear in abundance from the mid-August. Vertical distribution patterns of the larvae are closely related to the depth of the water column as well as to the current velocity. In shallow water the larvae tend to aggregate in the bottom layer, while they are diffused to some extent in deep water. In shallow water column ( 8m) more or less 75% of the total larvae individuals was observed in the lower 4m layer and in deep water column ( 16m) only 45% of those was found in the lower 4m layer. In the water of lower velocity a large fraction of the larvae population is distributed in the lower depth layer.

• Journal of Korean Society for Atmospheric Environment
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• v.23 no.4
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• pp.449-456
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• 2007

Dispersion coefficient preprocessing schemes have been examined to improve plume dispersion model performance in complex coastal areas. The performances of various schemes for constructing the sigma correction order were evaluated through estimations of statistical measures, such as bias, gross error, R, FB, NMSE, within FAC2, MG, VG, IOA, UAPC and MRE. This was undertaken for the results of dispersion modeling, which applied each scheme. Environmental factors such as sampling time, surface roughness, plume rising, plume height and terrain rolling were considered in this study. Gaussian plume dispersion model was used to calculate 1 hr $SO_2$ concentration 4 km downwind from a power plant in Boryeung coastal area. Here, measured data for January to December of 2002 were obtained so that modelling results could be compared. To compare the performances between various schemes, integrated scores of statistical measures were obtained by giving weights for each measure and then summing each score. This was done because each statistical measure has its own function and criteria; as a result, no measure can be taken as a sole index indicative of the performance level for each modeling scheme. The best preprocessing scheme was discerned using the step-wise method. The most significant factor influencing the magnitude of real dispersion coefficients appeared to be sampling time. A second significant factor appeared to be surface roughness, with the rolling terrain being the least significant for elevated sources in a gently rolling terrain. The best sequence of correcting the sigma from P-G scheme was found to be the combination of (1) sampling time, (2) surface roughness, (3) plume rising, (4) plume height, and (5) terrain rolling.

• Journal of the Korea Institute of Military Science and Technology
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• v.15 no.1
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• pp.93-100
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• 2012

In this paper, the deterministic optimal design for the tail plane made of composite materials is conducted under the deterministic loading condition and compared with that of the metallic materials. Next, the reliability analysis with five random variables such as loading and material properties of unidirectional prepreg is conducted to examine the probability of failure for the deterministic optimal design results. The MATLAB programing is used for reliability analysis combined with FEA S/W(COMSOL) for structural analysis. The laminated composite is assumed to the equivalent orthotropic material using classical laminated plate theory. The response surface methodology and importance sampling technique are adopted to reduce computational cost with satisfying the accuracy in reliability analysis. As a result, structural weight of composite materials is lighter than that of metals in deterministic optimal design. However, the probability of failure for the deterministic optimal design of the tail plane structures is too high to be neglected. The sensitivity of each variable is also estimated using probabilistic sensitivity analysis to figure out which variables are sensitive to failure. The computational cost is considerably reduced when response surface methodology and importance sampling technique are used. The study of the computationally inexpensive method for reliability-based design optimization will be necessary in further work.

• Computational Structural Engineering
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• v.7 no.1
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• pp.109-116
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• 1994

In this paper, various reliability analysis methods for calculating a probability of failure are investigated for their accuracy and efficiency. Crude Monte Carlo method is used as a basis for the comparison of various numerical results. For the sampling methods, Importance Sampling method and Directional Simulation method are considered for overcoming a drawback of Crude Monte Carlo method. For the approximate methods, conventional Rackwitz-Fiessler method. 3-parameter Chen-Lind method, and Rosenblatt transformation method are compared on the basis of First order reliability method. As a Second-order reliability method, Curvature-Fitting paraboloid method, Point-fitting paraboloid method, and Log-likelihood function method are explored in order to verify the accuracy of the reliability calculation results. These methods mentioned above would have some difficulty unless the limit state equation is expressed explicitly in terms of random design variables. Thus, there is a need to develop some general reliability methods for the case where an implicit limit state equation is given. For this purpose, Response surface method is used where the limit state equation is approximated by regression analysis of the response surface outcomes resulted from the structural analysis. From the application of these various reliability methods to three examples, it is found that Directional Simulation method and Response Surface method are very efficient and recommendable for the general reliability analysis problem cases.

• Journal of the Korean Chemical Society
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• v.44 no.6
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• pp.547-555
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• 2000

The surface water in the upstream and midstream of Nakdong river, which is being used as tap water and industrial water supply in Daegu city and Kyungpook province, was analyzed in its water quality. In addition, the sediments of which was analyzed in terms of heavy metal and organic substance contents. All the sampling was done in the drought season for 2 days of June 22-23 and carried out in 10 sampling sites. The sites cover the whole Kyungpook provincial region, starting from Yangsam Bridge in Chyeong Ryang Provincial Park as the upper end, to the Ko Ryung Bridge as the lower end sampling site of Nakdong river that flows through Kyungpook province. The 22 items including $NH^{+}_{4}$, $NO^{-}_{2}$ and COD were analyzed for surface water and 11 items including organic constituents(trichloroethylene, etc) and heavy metals were analyzed for sediments. The sediments samples were analyzed by elution testing method and acid dissolution method and then the results were compared with each other. All heavy metals in samples were determined by Inductively Coupled Plasma-Atomic Emission Spectroscopy(ICP-AES) and other constituents were analyzed by standard testing methods of the Korean Ministry of Environment.

• Journal of Soil and Groundwater Environment
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• v.7 no.3
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• pp.71-77
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• 2002

This research was carried out from 2001. 4 until 2001. 5 in order to examine the level of soil contamination in the vicinity of Nanjido. The sampling was done at near the Nanjido soil. At the each sampling site we did the sampling at different depth- surface(0~15cm deep), 1m deep, 2m deep, 3m deep. The contamination of Cd, Cu, Pb, As, $Cr^{+6}$, and Hg were tasted and analysed by spectra AA. The examination showed that the average concentration level of the entire sampled soil was Cd, 0.229mg/kg, Cu 8.349mg/kg, Pb : 11.083mg/kg, As : 0.298mg/kg, $Cr^{+6}$ : 0.124mg/kg, and Hg : 0.134mg/kg. The concentration level of at the depth of 0-l5cm, came out to be Cd : 0.305mg/kg, Cu : 8.464mg/kg, Pb : 11 383mg/kg, As : 0.128mg/kg, $Cr^{+6}$ : 0.153mg/kg, and Hg : 0.092mg/kg. It shows that in the cases of Cd and C $r^{+6}$ the average concentration level of the whole sampled soil was about 80% of that of 0-l5cm depth. And as for Hg and As. the average concentration level of the entire sampled soil came out to be approximately twice as high as the sample soil from the depth surface, As for Cu and Pb, there was not much difference between the entire samples average concentration level and the concentration level of surface. It was hard to find much relationship between the depth of each site where sampling was done and the level of concentration, the concentration level of Pb and Cu at the sampling site C and E was quite high, which suggests that it has been affected by the polluted the hyang-dong stream and fill random up waste.