• Journal of the Korean Society of Radiology
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• v.1 no.1
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• pp.25-30
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• 2007

ROC(Receiver Operating Characteristic)curve is the method that estimate detected insignificant signal from the human's sense of sight, it has been raised excellent results. In this study, we evaluate image quality and equipment character by obtaining a chest image from CR(Computed Radiography) and DDR(Direct Digital radiography) using the human chest phantom, The parameter of exposure for obtaining chest image was 120 kVp/3.2 mAs and the SID(Source to Image Distance) was 180cm. The images were obtained by CR(AGFA MD 4.0 General plate, JAPAN) and DDR(HOLOGIC nDirect Ray, USA). Using some pieces of Aluminum and stone for expressing regions, then attached them on the heart, lung and thoracic vertebrae of the phantom. 29 persons hold radiology degrees were participated in ROC analysis. As a result of the ROC analysis, TPF(true positive fraction) and FPF(false positive fraction) of DDR and CR are 0.552 and 0.474 and 0.629 and 0.405, respectively. By using the results, the ROC curve of CR has higher image quality than DDR. According to the theory, DDR has the higher image quality than CR in chest X-ray image. But, CR has the higher image quality than DDR. quality of DDR inserted the enhance board. The results confirmed that image post-processing is important element decipherment of clinical.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.37 no.1
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• pp.83-91
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• 2017

In case of estimation of settlement for the piled-raft foundation, it is necessary to consider interaction among raft, piles and soil. But, simple analytic methods usually are not applicable to considering this complicated interaction. In this study, a computer-based approximate analytic method, HDPR, was developed in consideration of above mentioned interaction in order to analysis of settlement for the piled-raft foundation. The finite element method was applied to raft analysis by means of the Mindlin plate theory, and soil and piles were modeled as springs which were connected with their raft. The linear spring which can consider multi layered soil and the non-linear spring were applied to soil springs and pile springs, respectively. The raft-piles-soil interaction was reflected to each spring. In order to verify the developed analytic method, it was compared and analyzed with 3D FEM analysis, existing approximate analytic method and site monitoring data. As a result, the developed analytic method showed reasonable results of settlement estimations of raft and piles for each case. From a practical point of view, it is confirmed that this analytic method is able to apply for analysis and design of the piled-raft foundation.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.34 no.5
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• pp.18-38
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• 2002

A previous study on the model coatings based on latex-bound plastic pigment coatings (1) has been extended to latex-bound No. 1 clay, ultra-fine ground calcium carbonate (UFGCC), and clay-carbonate pigment mixture coatings, which are being widely used in the paper industry. The latex binder used was a good film-forming, monodisperse S/B latex or 0.15$\mu\textrm{m}$. No. 1 clay was representative of plate-like pigment particles, whereas UFGCC was of somewhat rounded rhombohedral pigment particlel. Both of them had negatively skewed triangular particle size distributions having the mean particle suet of 0.7${\mu}{\textrm}{m}$ and 0.6$\mu\textrm{m}$, respectively. Their packing volumes were found to be 62.5% and 657%, respectively. while their critical pigment volume concentrations (CPVC's) were determined to be 52.7% and 50.5% ( average of 45% caused by the incompatibility and 55.9% extrapolated) by coating porosity, respectively. Each pigment/latex coating system has shown its unique relationship between coating properties and pigment concentrations, especially above its CPVC. Notably, the clay/latex coating system hat shown higher coating porosity than the UFGCC/latex system at high pigment concentrations above their respective CPVC's. It was also found that their coating porosity and gloss were inter-related to each other above the CPVC's, as predicted by the theory. More interestingly, the blends of these two pigments have shown unique rheological and coating properties which may explain why such pigment blends are widely used in the industry. These findings have suggested that the unique structure of clay coatings and the unique high-shear rheology of ground calcium carbonate coatings can be judiciously combined to achieve superior coatings. Importantly, the low-shear viscosity of the blends was indicative of their unique packing and coating structure, whereas their high-shear rheology was represented by a common mixing rule, i.e., a viscosity-averaging. Transmission and scanning electron and atomic force microscopes were used to probe the state of pigment / latex dispersions, coating surfaces, freeze fractured coating cross-sections, and coating surface topography. These microscopic studies complemented the above observations. In addition, the ratio, R, of CPVC/(Pigment Packing Volume) has been proposed as a measure of the binder efficiency for a given pigment or pigment mixtures or as a measure of binder-pigment interactions. Also, a mathematical model has been proposed to estimate the packing volumes of clay and ground calcium carbonate pigments with their respective particle size distributions. As well known in the particle packing, the narrower the particle size distributions, the lower the packing volumes and the greater the coating porosity, regardless of particle shapes.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.34 no.1
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• pp.59-69
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• 2021

Recently, large-scale offshore and coastal structures have been constructed owing to the increasing interest in eco-friendly energy development. To achieve this, precise simulations of waves are necessary to ensure the safe operations of marine structures. Several experiments are required in the field to understand the offshore wave; however, in terms of scale, it is difficult to control variables, and the cost is significant. In this study, numerical waves under various wave conditions are produced using a piston-type wavemaker, and the produced wave profiles are verified by comparing with the results from a numerical wave tank (NWT) modeled using the smoothed particle hydrodynamics (SPH) method and theoretical equations. To minimize the effect by the reflected wave, a mass-weighted damping zone is set at the right end of the NWT, and therefore, stable and uniform waves are simulated. The waves are generated using the linear and Stokes wave theories, and it is observed that the numerical wave profiles calculated by the Stokes wave theory yield high accuracy. When the relative depth is smaller than two, the results show good agreement irrespective of the wave steepness. However, when the relative depth and wave steepness are larger than 2 and 0.04, respectively, the errors are negligible if the measurement position is close to the excitation plate. However, the error is 10% or larger if the measurement position is away from the excitation location. Applicable target wave ranges are confirmed through various case studies.

• Steel and Composite Structures
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• v.47 no.1
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• pp.91-102
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• 2023

To study the evaluation standard and control limit of mortar filling layer void length, in this paper, the train sub-model was developed by MATLAB and the track-bridge sub-model considering the mortar filling layer void was established by ANSYS. The two sub-models were assembled into a train-track-bridge coupling dynamic model through the wheel-rail contact relationship, and the validity was corroborated by the coupling dynamic model with the literature model. Considering the randomness of fastening stiffness, mortar elastic modulus, length of mortar filling layer void, and pier settlement, the test points were designed by the Box-Behnken method based on Design-Expert software. The coupled dynamic model was calculated, and the support vector regression (SVR) nonlinear mapping model of the wheel-rail system was established. The learning, prediction, and verification were carried out. Finally, the reliable probability of the amplification coefficient distribution of the response index of the train and structure in different ranges was obtained based on the SVR nonlinear mapping model and Latin hypercube sampling method. The limit of the length of the mortar filling layer void was, thus, obtained. The results show that the SVR nonlinear mapping model developed in this paper has a high fitting accuracy of 0.993, and the computational efficiency is significantly improved by 99.86%. It can be used to calculate the dynamic response of the wheel-rail system. The length of the mortar filling layer void significantly affects the wheel-rail vertical force, wheel weight load reduction ratio, rail vertical displacement, and track plate vertical displacement. The dynamic response of the track structure has a more significant effect on the limit value of the length of the mortar filling layer void than the dynamic response of the vehicle, and the rail vertical displacement is the most obvious. At 250 km/h - 350 km/h train running speed, the limit values of grade I, II, and III of the lengths of the mortar filling layer void are 3.932 m, 4.337 m, and 4.766 m, respectively. The results can provide some reference for the long-term service performance reliability of the ballastless track-bridge system of HRS.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.4
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• pp.363-371
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• 2023

To construct a ship, blocks of various sizes must be moved and erected . In this process, lugs are used such that they match the block fastening method and various functions suitable for the characteristics of each shipyard facility. The sizes and shapes of the lugs vary depending on the weight and shape of the block structures. The structure is reinforced by welding the doubling pads to compensate for insufficient rigidity around the holes where the shackle is fastened. As for the method of designing lugs according to lifting loading conditions, a simple calculation based on the beam theory and structural analysis using numerical modeling are performed. In the case of the analytical method, a standardized evaluation method must be established because results may differ depending on the type of element and modeling method. The application of this ambiguous methodology may cause serious safety problems during the process of moving and turning-over blocks. In this study , the effects of various parameters are compared and analyzed through numerical structural analysis to determine the modeling conditions and evaluation method that can evaluate the actual structural response of the lug. The modeling technique that represents the plate part and weld bead around the lug hole provides the most realistic behavior results. The modeling results with the same conditions as those of the actual lug where only the weld bead is connected to the main body of the lug, showed a lower ulimated strength compared with the results obtained by applying the MPC load. The two-dimensional shell element is applied to reduce the modeling and analysis time, and a safety working load was verified to be predicted by reducing the thickness of the doubling pad by 85%. The results of the effects of various parameters reviewed in the study are expected to be used as good reference data for the lug design and safe working load prediction.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.47 no.6
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• pp.395-401
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• 2002

The combination of early heading time, maturing time and short grain-filling period is very important to develop early varieties in winter barley. The 4 parental half diallel crosses (parents, $F_1$s, $F_2$s) were cultivated at the field. The heading date was from April 3 to 26, maturing date from May 15 to 27 and grain-filling period from 31 days to 42 days, showing that the varietal differences about the 3 traits were remarkable. According to half diallel cross analyses, Dongbori 1 for heading time (late heading) was dominant, but Oweolbori (early heading) was recessive, showing partial dominance with high additive component of genetic variance. Dongbori 1 for maturing time was dominant, but Oweolbori was recessive, showing partial dominance with high additive variance. Reno for grain-filling period (short grain-filling period) was dominant, but Oweolbori (long grain-filling period) was recessive with additive, and partial dominance. There were highly significant mean squares for both GCA and SCA effects on the heading and maturing times, and GCA/SCA ratios for all traits were high, showing the additive gene effects more important. Sacheon 6 and Oweolbori had greater GCA effects for early heading and maturing times, and Dongbori 1 and Reno had greater GCA effects for late times. GCA effects were highly significant in $F_1$ and $F_2$ generations, showing high GCA/SCA ratios (7.02). The heading and maturing times in field were positively correlated with antifreeze proteins concentrations, accumulation, resistance to photoinhibition and winter survival, respectively) but the grain-filling period did negatively correlated with the trails.

• Journal of Soil and Groundwater Environment
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• v.9 no.1
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• pp.79-86
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• 2004

Hydraulic conductivity along rock fracture is mainly dependent on fracture geometries such as orientation, aperture, roughness and connectivity. Therefore, it needs to consider fracture geometries sufficiently on a fracture model for a numerical analysis to calculate permeability coefficient in a fracture. This study performed new type of numerical analysis using a homogenization analysis method to calculate permeability coefficient accurately along single fractures with several fracture models that were considered fracture geometries as much as possible. First of all, fracture roughness and aperture variation due to normal stress applied on a fracture were directly measured under a confocal laser scaning microscope (CLSM). The acquired geometric data were used as input data to construct fracture models for the homogenization analysis (HA). Using the constructed fracture models, the homogenization analysis method can compute permeability coefficient with consideration of material properties both in microscale and in macroscale. The HA is a new type of perturbation theory developed to characterize the behavior of a micro inhomogeneous material with a periodic microstructure. It calculates micro scale permeability coefficient at homogeneous microscale, and then, computes a homogenized permeability coefficient (C-permeability coefficient) at macro scale. Therefore, it is possible to analyze accurate characteristics of permeability reflected with local effect of facture geometry. Several computations of the HA were conducted to prove validity of the HA results compared with the empirical equations of permeability in the previous studies using the constructed 2-D fracture models. The model can be classified into a parallel plate model that has fracture roughness and identical aperture along a fracture. According to the computation results, the conventional C-permeability coefficients have values in the range of the same order or difference of one order from the permeability coefficients calculated by an empirical equation. It means that the HA result is valid to calculate permeability coefficient along a fracture. However, it should be noted that C-permeability coefficient is more accurate result than the preexisting equations of permeability calculation, because the HA considers permeability characteristics of locally inhomogeneous fracture geometries and material properties both in microscale and macroscale.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.39 no.1
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• pp.56-62
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• 2003

To investigate the entrapping behavior of blue crab, rock shell and green ling, which are mainly caught with the other trap nets in the coastal area of Yellow Sea, by the using duration of trap nets through the water tank experiment. We select the three kinds of trap nets which have different using duration such as new, 6 months and 12 months used one, and observe the entrapping ratio into the trap nets, respectively. In the mean while, in order to obtain the basic data for the estimate of mesh selectivity of the other trap nets, the entrapping behavior into the trap nets for green ling which has high activity compared to blue crab and rock shell, are examined to the three kinds of mesh size (35mm, 50mm and 65mm). The results are as follows ; 1. The mean entrapping ratio of blue crab by the using duration of trap nets in high with 4.4 fishes (44.0%) in the 6 months used one, become lower with 2.9 fishes (28.0%) in the new one, and with 2.0 fishes (20.0%) in the 12 months used one. 2. The mean entrapping ratio of rock shell by the using duration of trap nets in high with 7.3 fishes (36.7%) in the new one, and become lower with 7.2 fishes (35.8%) in the 6 months used one, and with 5.7 fishes (28.3%) in the 12 months used one. 3. The mean entrapping ratio of green ling by the using duration of trap nets in high with 3.4 fishes (34.0%) in the 6 months used one, and become lower with 3.0 fishes (30.0%) in the new one, and with 2.8 fishes (28.0%) in the 12 months used one. 4. The mean residual ratio of green ling by the mesh size of trap nets is high with 2.4 fishes (24.0%) in the 35mm mesh size, and become lower with 2.2 fishes (22.0%) in the 50mm mesh size and 2.0 fishes (20.0%) in the 65mm mesh size.

• Journal of Veterinary Clinics
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• v.21 no.4
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• pp.329-335
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• 2004

Dog spermatozoa were recovered from the caudae epididymides of 23 domestic dogs which were 11 pure breed and 12 mix-breed dogs ranging in age from 0.6 to 3 years. The experimental designs were as follows: 1) the effect of chilling to 0. 10 or 37$^{\circ}C$. 2) the kinetics of chilling injury at 0 or 4$^{\circ}C$, and 3) the effect of sugars at $0^{\circ}C$. Viable spermatozoa were recovered by percoll gradient separation and adjusted to 5${\times}$10$^{7}$ spermatozoa/ml. In experiment 1, spermatozoa were diluted with 0.33 M glucose supplemented with 3% BSA (G-BSA) at 1:2 dilution. Spermatozoa were loaded into straws and exposed at 0, 10 or 37$^{\circ}C$ for 30 min. In experiment 2, spermatozoa were prepared as the experiment 1 and exposed for 0.5, 5, 15, or 30 min at 0 or 4$^{\circ}C$. In experiment 3, spermatozoa were diluted with different sugars (0.33 M galactose, glucose, fructose, mannitol, lactose, sucrose, raffinose) and cooled to $0^{\circ}C$ for 30 min. Sperm membrane integrity, motility and acrosome integrity were assayed after rewarming at 37$^{\circ}C$ for 5 min. Sperm motility and membrane integrity abruptly decreased with decreasing temperature but acrosome integrity gradually decreased (P<0.05). Sperm motility was more sensitive to cold shock than membrane integrity and acrosome integrity. Spermatozoa cooled to $0^{\circ}C$ were more damaged than those at 4$^{\circ}C$. Sperm motility was not different among exposed times at both. 0 and 4$^{\circ}C$. However, membrane integrity of spermatozoa exposed for 30 min at both 0 and 4$^{\circ}C$ was significantly lower (P<0.05). Spermatozoa diluted in 0.33 M fructose or galactose showed lower motility and higher morphological abnormality with coiled tail at $0^{\circ}C$. These sperm characteristics were strongly related. These results indicate that dog epididymal spermatozoa are relatively sensitive to rapid cooling and higher morphological abnormality at $0^{\circ}C$ was shown in spermatozoa diluted in fructose and galactose.