• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.26 no.2
• /
• pp.165-173
• /
• 2008

This study aims at generating automatically three dimensional geometric models of roads using LIDAR data and a digital map. The main processes in the proposed method are (1) generating a polygon encompassing a road region using a road layer from the digital map, (2) extracting LIDAR points within the road region using the polygon, (3) organizing the points into surface patches and grouping the patches into surface clusters, (4) searching the road surface clusters and generating the surface model from the points linked to the clusters, (5) refining the boundary using a digital map. By applying the proposed method to real data, we successfully generated the linear and surface information of the roads.

• Journal of Welding and Joining
• /
• v.14 no.1
• /
• pp.68-74
• /
• 1996

The microstructure of HAZ and the mechanical properties in weldments such as hardness and toughness were studied for mild steel and AH36 grade TMCP steel, as increasing heat input with electrogas welding process. The results of this study can be summarized as follow: 1) In the HAZ of mild steel, the width of coarse grained zone was larger than that of the nomalized zone, however in the case of TMCP steel, the nomalized zone was wider than the coarse grained zone. 2) The grain size of HAZ become coarse with increasing heat input. And at the same heat input, the grain size of TMCP steel was more coarser than that of mild steel. 3) According to the change of heat input, the deviation of hardness values was not significant, and the maximum values of hardness was not in HAZ but in the weld metal. And the hardness values in root part was higher than in face part. 4) Even though the HAZ grain size of mild steel was larger than that of TMCP steel, the impact values for mild steel was higher than those for TMCP steel, and the impact values in face part was higher than those in root part.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.12 no.4
• /
• pp.892-899
• /
• 1988

A container crane model was tested to investigate wind-load characteristics in uniform flows and ground boundary layers. Drag coefficients and moment coefficients show their minimum values at 0, 90, 180 degrees wind directions and maximum values at 60 and 120 degrees. Strong interactions among structure elements produce such variations of the wind-load with wind directions. The BS-2573 code is shown to over-estimation can be reflected in the design stage of cranes by refining the rule of the designer. Some roundings of coners of the engine room and the machinery room reduce the wind-load by 10 percents. Considerable reductions of the wind-load would be expected if further integrated development of the crane structure are executed.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.23 no.4
• /
• pp.313-325
• /
• 2011

Finite element grid system using h-refinement on the Yellow Sea was constructed based on previous study (Suh, 1999b) from 14 K to 210 K and special attention was concentrated on refining the coastal zone. In grid generation, depth change between adjacent points and non-dimensional tidal wave length ratio were considered. As a result approximately a quarter of the total nodes are located nearby 5 m of shallow area. Accurate bathymetry data using 30's and ETOPO1 with open boundary conditions of 8 major tidal constituents extracted automatically from FES2004 have been applied. In tidal simulation a 3-dimensional nonlinear harmonic model was setup and tidal amplification due to changes in vertical turbulent and bottom friction were simulated. In this study not only 8 major tidal constituents but also nonlinear shallow tides $M_4,$, $MS_4$ and long period $M_f,$, $M_{sf}$ were reproduced. It is found that implication of spatial variation of friction coefficient plays a very important role in reproduction of astronomical and shallow tides which are computed by iterative computation of nonlinear terms. Also it should be considered differently with respect to tidal periods. To understand the distribution of tidal asymmetry, amplitude ratio of $M_4/M_2$ and phase differences $2g(M_2)-g(M_4)$ were calculated. Tidal distortion ratio marks up to 0.2 on the west coast showing shallow coastal characteristics and somewhat wide range of ebb-dominances in front of Mokpo area are reproduced.

• Journal of KIISE:Computer Systems and Theory
• /
• v.29 no.11
• /
• pp.589-600
• /
• 2002

Deformable models offer an attractive approach for extracting three-dimensional boundary structures from volumetric images. However, conventional deformable models have three major limitations - sensitive to initial condition, difficult to represent complex boundaries with severe object concavities and protrusions, and self-intersective between model elements. This paper proposes a deformable model that is effective to extract geometrically complex boundary surfaces by improving away the limitations of conventional deformable models. First, the proposed deformable model resamples its elements hierarchically based on volume image pyramid. The hierarchical resampling overcomes sensitivity to initialization by extracting the boundaries of objects in a multiscale scheme and enhances geometric flexibility to be well adapted to complex image features by refining and regularizing the size of model elements based on voxel size. Second, the physics-based formulation of our model integrates conventional internal and external forces, as well as a non-self-intersecting force. The non-self-intersecting force effectively prevents collision or crossing over between non-neighboring model elements by pushing each other apart if they are closer than a limited distance. We show that the proposed model successively extracts the complex boundaries including severe concavities and protrusions, neither depending on initial position nor causing self-intersection, through the experiments on several computer-generated volume images and brain MR volume images.

• Journal of Advanced Marine Engineering and Technology
• /
• v.40 no.7
• /
• pp.574-579
• /
• 2016

Grid systems used in previous studies were determined to be valid only if the length between the perpendiculars in a model ship was in the range of 6-8 m, and the maximum dynamic trim angle was smaller than $1^{\circ}$. The application of the grid system to a small fishing boat can create numerical instability because the dynamic trim of small boats is generally larger than $3^{\circ}$, and their Froude numbers are in the range of 0.3-0.8. In the present study, resistances of a small fishing boat were stably obtained by reducing the length between the center of buoyancy and the inlet boundary of the numerical domain, and by refining grid cells vertically in a region that would be swept by a free surface. The effective power of the small fishing boat was predicted based on the ITTC-1978 two-dimensional analysis. By using the results of previous towing tank tests, the coefficient of quasi-propulsive efficiency and the brake horsepower at a design draft were calculated.

• Korean Journal of Materials Research
• /
• v.21 no.10
• /
• pp.556-562
• /
• 2011

We carried out this study to evaluate the grain refining in and the mechanical properties of alloys that undergo severe plastic deformation (SPD). Conventional rolling (CR) and cross-roll rolling (CRR) as SPD methods were used with Ni-20Cr alloy as the experimental material. The materials were cold rolled to a thickness reduction of 90% and subsequently annealed at $700^{\circ}C$ for 30 min to obtain a fully recrystallized microstructure. For the annealed materials after the cold rolling, electron back-scattered diffraction (EBSD) analysis was carried out to investigate the grain boundary characteristic distributions (GBCDs). The CRR process was more effective when used to develop the grain refinement relative to the CR process; as a result, the grain size was refined from $70{\mu}m$ in the initial material to $4.2{\mu}m$ (CR) and $2.4{\mu}m$ (CRR). These grain refinements have a direct effect on improving the mechanical properties; in this case, the microhardness, yield and tensile strength showed significant increases compared to the initial material. In particular, the CRR-processed material showed more effective values relative to the CR-processed materials. The different texture distributions in the CR (001//ND) and CRR (111//ND) were likely the cause of the increase in the mechanical properties. These findings suggest that CRR can result in materials with a smaller grain size, improved texture development and improved mechanical properties after recrystallization by a subsequent annealing process.

• Journal of Digital Policy
• /
• v.3 no.1
• /
• pp.27-32
• /
• 2024

In this paper, proposes a super resolution method that enhances the quality of results by refining texture features, contrasting each, and utilizing the results as weights. For the improvement of quality, a precise and clear restoration result in details such as boundary areas is crucial in super resolution, along with minimizing unnecessary artifacts like noise. The proposed method constructs a residual block structure with multiple paths and skip-connections for feature estimation in conventional Convolutional Neural Network (CNN)-based super resolution methods to enhance quality. Additional learning is performed for sharpened and blurred image results for further texture analysis. By contrasting each super resolution result and allocating weights through this process, the proposed method achieves improved quality in detailed and smoothed areas of the image. The experimental results of the proposed method, evaluated using the PSNR and SSIM values as quality metrics, show higher results compared to existing algorithms, confirming the enhancement in quality.

• Journal of Korean Society of Occupational and Environmental Hygiene
• /
• v.29 no.1
• /
• pp.34-41
• /
• 2019

Objective: This study is conducted to evaluate airborne lead concentration in and around lead production plant. Methods: Airborne lead concentration was monitored simultaneously inside of the processes of lead recycling factory and outside of factory which include stack, boundary of factory and residential area 1 km and 7.5 km from factory, respectively. All samples were measured three times at 1.5 m from the ground and analyzed using inductively coupled plasma mass spectrometer, inductively coupled plasma optical emission spectrometer or flame atomic absorption spectrometer. Results: All airborne lead concentrations measured inside of factory($13.9{\mu}g/m^3-252.9{\mu}g/m^3$) and outside of factory($0.001{\mu}g/m^3-54.97{\mu}g/m^3$) showed log-normal distribution. Geometric mean lead concentration, $54.81{\mu}g/m^3$, measured inside of factory was significantly higher than outside of factory, $0.20{\mu}g/m^3$(p<0.01). Among the samples measured inside the factory, lead concentration was the highest in the refining process($59.02{\mu}g/m^3-252.9{\mu}g/m^3$). In the case of the samples outside the factory, the nearest chimney was the highest($3.84{\mu}g/m^3-54.97{\mu}g/m^3$), and the lead concentration at the farthest place, 7.5 km from the factory was the lowest($0.001{\mu}g/m^3-1.7{\mu}g/m^3$). The arithmetic lead concentration, $0.45{\mu}g/m^3$ in the residential area near the factory was below the atmospheric environment standard of $0.5{\mu}g/m^3$, but the maximum concentration of $3.4{\mu}g/m^3$ was exceeded. Conclusions: Airborne lead concentration in residential area, 1 km away from lead recycling plant, may exceed ambient air standard of $0.5{\mu}g/m^3$.