• Journal of Korea Multimedia Society
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• v.13 no.3
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• pp.430-437
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• 2010

It is essential for living donor liver transplantation that surgeon must understand the hepatic vessel structure to improve the success rate of operation. In this paper, we extract the liver boundary without other surrounding structures such as heart, stomach, and spleen using the contrast enhanced MDCT liver image sequence. After that, we extract the major hepatic veins (left, middle, right hepatic vein) with morphological filter after review the basic structure of hepatic vessel which reside in segmented liver image region. The purpose of this study is provide the overall status of transplantation operation with size estimation of resection part which is dissected along with the middle hepatic vein. The method of liver extraction is as follows: firstly, we get rid of background and muscle layer with gray level distribution ratio from sampling process. secondly, the coincident images match with unit mesh image are unified with resulted image using the corse coordinate of liver and body. thirdly, we extract the final liver image after expanding and region filling. Using the segmented liver images, we extract the hepatic vessels with morphological filter and reversed the major hepatic vessels only with a results of ascending order of vessel size. The 3D reconstructed views of hepatic vessel are generated after applying the interpolation to provide the smooth view. These 3D view are used to estimate the dissection line after identify the middle hepatic vein. Finally, the volume of resection region is calculated and we can identify the possibility of successful transplantation operation.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.221-221
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• 2014

The present work proposes an improved numerical simulator for design and modification of large area capacitively coupled plasma (CCP) processing chamber. CCP, as notoriously well-known, demands the tremendously huge computational cost for carrying out transient analyses in realistic multi-dimensional models, because electron dissociations take place in a much smaller time scale (${\Delta}t{\approx}10-8{\sim}10-10$) than time scale of those happened between neutrals (${\Delta}t{\approx}10-1{\sim}10-3$), due to the rf drive frequencies of external electric field. And also, for spatial discretization of electron flux (Je), exponential scheme such as Scharfetter-Gummel method needs to be used in order to alleviate the numerical stiffness and resolve exponential change of spatial distribution of electron temperature (Te) and electron number density (Ne) in the vicinity of electrodes. Due to such computational intractability, it is prohibited to simulate CCP deposition in a three-dimension within acceptable calculation runtimes (<24 h). Under the situation where process conditions require thickness non-uniformity below 5%, however, detailed flow features of reactive gases induced from three-dimensional geometric effects such as gas distribution through the perforated plates (showerhead) should be considered. Without considering plasma chemistry, we therefore simulated flow, temperature and species fields in three-dimensional geometry first, and then, based on that data, boundary conditions of two-dimensional plasma discharge model are set. In the particular case of SiH4-NH3-N2-He CCP discharge to produce deposition of SiNxHy thin film, a cylindrical showerhead electrode reactor was studied by numerical modeling of mass, momentum and energy transports for charged particles in an axi-symmetric geometry. By solving transport equations of electron and radicals simultaneously, we observed that the way how source gases are consumed in the non-isothermal flow field and such consequences on active species production were outlined as playing the leading parts in the processes. As an example of application of the model for the prediction of the deposited thickness uniformity in a 300 mm wafer plasma processing chamber, the results were compared with the experimentally measured deposition profiles along the radius of the wafer varying inter-electrode gap. The simulation results were in good agreement with experimental data.

• Journal of Wetlands Research
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• v.19 no.2
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• pp.202-210
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• 2017

Shear stress is one of the most important mechanical factors used in various fields and is important for the design of artificial channels. Current shear stresses have been used in the past, but there are factors that are difficult to actually measure or calculate, such as bed shear stress and energy slope in the equation used. In particular, the energy slope is a very difficult factor to estimate, and it is difficult to estimate the slope and flow velocity of the boundary layer although the energy slope can be used to obtain the shear stress distribution. In addition, the bed shear stress among the shear stress distribution is very difficult to measure directly, and the research is somewhat slower than the velocity. In this study, we have studied the simple calculation of the average flow velocity and the shear stress distribution using entropy M without reflecting the energy gradient, and we used existing laboratory data to demonstrate the utility of the applied equation. The stress distribution in the graphs was comparatively analyzed. In the case of the uniform flow and the non-uniform flow, the correlation coefficient was almost identical to 0.930-0.998.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.32 no.3
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• pp.21-31
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• 2014

This study aims to comparison of spatial composition that Okhojeong garden and Seokpajeong garden. Construct background and space structure in both of Okhojeong garden and Seokpajeong garden is analyzed. The results were as follows. First, Okhojeong garden and Seokpajeong garden of the nobles gardens in late Joseon dynasty. They had the advanced techniques of contemporary based on their political power and wealth, and therefore could built garden and enjoy the garden culture of the upper layer. Furthermore, composition of the Okhojeong garden can be assumed that it is related to construction of the Seokpajeong garden through analysis of the relationship between builders. Secondly, Space structure of Okhojeong garden and Seokpajeong garden is divided into pavilion unit of small gardens with living space as the center. Construction pavilion in each garden space imbues certain landscape theme. In addition, authorization of characteristics of a place in each area is attempted through boundary establishment and selective garden culture of varied seasonal landscape. Thirdly, In Seokpajeong garden, most of construction characteristics of Okhojeong garden are appeared. This indicates that Seokpajeong garden was affected by space-configuration-technique of Okhojeong garden such as acceptation or modification recreation. Fourth, In many cases, fanciers regarding floriculture are expanded to enthusiasts in late Joseon dynasty. In Okhojeong garden and Seokpajeong garden, herbaceous ornamental is considered to be precious and garden materials such as water tray, stone couch, oddly shaped stone, potted plant, artificial hill, wisteria trellis are diversified at the time.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.9
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• pp.69-76
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• 2018

The present study analyzed the effect of film hole position of 45 degree ribbed cooling channel on film cooling performance of gas turbine blades. We also investigated the influence of the ribs under the fixed blowing ratio. Three-dimensional numerical model was constructed and extensive simulation was conducted using the commercial code (Fluent ver. 17.0) under steady-state condition. Base on the simulation results, We investigated the cooling effectiveness, flow velocity, streamline, and pressure coefficient. Moreover, We analyzed the effect of cooling hole position on ejection of the secondary flow caused by the rib structure. From the results, It was found that internal flow of the cooling channel forms a vortex pair in the counterclockwise from the top side, and clockwise from the bottom side. For the channels with ribs, the vortex flow generated by the ribs caused a higher pressure difference near the hole outlet, resulting in at least 12% higher cooling effectiveness than the channel without ribs. Additionally, when the hole is located on the left side of the ribbed channel (Rib-Left), it can be found that the secondary flow generated by the ribs hits against wall surface near the hole to form a flow in the direction of the hole inclination angle. Therefore, It is considered that the region where the cooling gas discharged to the blade surface stays in the main flow boundary layer is wider than the other cases. In this case, The largest pressure coefficient difference was observed near the outlet of the hole, and as a result, the discharge of the cooling gas was accelerated and the cooling efficiency was slightly increased.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.04a
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• pp.835-841
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• 2013

Modern solid-state gyroscopes (HRG) with hemispherical resonators from high-purity quartz glass and special surface superfinishing and ultrathin gold coating become the best instruments for precise-grade inertial reference units (IRU) targeting long-term space missions. Designing of these sensors could be a notable contribution into development of Korea as a space nation. In participial, 40mm diameter thin-shell resonator from high-purity fused quartz, fabricated as a single-piece with its supporting stem has been designed, machined, etched, tuned, tested, and delivered by STM Co. (ATS of Ukraine) several years ago; an extremely-high Q-factor (upto 10~20 millions) has been shown. Understanding of the best way how to match such a unique sensor with inner glass assembly of the gyro means how to use the high potential in a maximal extent; and this has become the urgent task. Inner quartz glass assembly has a very thin indium (In) layer soldered the resonator and its silica base (case), but effects of internal resonances between operational modal pair of the shell-cup and its side (parasitic) modes can notable degrade the potential of the sensor as a whole, instead of so low level of resonator's intrinsic losses. Unfortunately, there are special combinations of dimensions of the parts (so-called, "resonant sizes"), when intensive losses of energy occurs. The authors proposed to use the length of stem's fixture as an additional design parameter to avoid such cases. So-called, a cyclic scheme of finite element method (FEM) and ANSYS software were employed to estimate different combinations of gyro assembly parameters. This variant has no mismatches of numerical origin due to FEM's discrete mesh. The optimum length and dangerous "resonant lengths" have been found. The special attention has been paid to analyses of 3D effects in a cup-stem transient zone, including determination of a difference between the positions of geometrical Pole of the resonant hemisphere and of its "dynamical Pole", i.e., its real zone of oscillation node. Boundary effects between the shell (cup) and 3D short "beams" (inner and outer stems) have been ranged. The results of the numerical experiments have been compared with the classic model of a quasi-hemispherical shell band with inextensional midsurface, and the solution using Rayleigh's functions of the $1^{st}$ and $2^{nd}$ kinds. To guarantee the truth of the recommended sizes to a designer of the real device, the analytical and FEM results have been compared with experimental data for a party of real resonators. The consistency of the results obtained by different means has been shown with errors less than 5%. The results notably differ from the data published earlier by different researchers.

• Applied Chemistry for Engineering
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• v.20 no.6
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• pp.638-645
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• 2009

High alumina refractory used in a coal gasifier was analyzed and the degradation mechanism by molten slag was investigated. The depth of refractory severely damaged by slag varied between 12~40 mm, including the adhered slag layer. The sample also showed the cracks formed in parallel to the slag/refractory interface. The degree of degradation varied with the micro-structures in the refractory. Fused alumina grains showed the uneven boundary and pore formation just along the edges, while the tablet alumina showed the slag penetrated between sintered alumina around which the formation of Al-Fe phase was observed. Calcium aluminate cements were not observed at the high temperature zone near the slag/refractory interface, probably due to dissolution into molten slag. Around large grains of alumina, rod shape alumina, which appeared to be recrystallized during cooling, were observed, and large pores were also formed around those grains. Therefore, in high alumina refractories, hot molten slag dissolves the bonding phase and rod-shape alumina phase is recrystallized upon cooling. During this process, cracks are developed due to structural change, and the degradation occurs by physical causes such as structural spalling.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2018.06a
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• pp.102-102
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• 2018

Electronic industry had required the finer size and the higher performance of the device. Therefore, 3-D die stacking technology such as TSV (through silicon via) and micro-bump had been used. Moreover, by the development of the 3-D die stacking technology, 3-D structure such as chip to chip (c2c) and chip to wafer (c2w) had become practicable. These technologies led to the appearance of HBM (high bandwidth memory). HBM was type of the memory, which is composed of several stacked layers of the memory chips. Each memory chips were connected by TSV and micro-bump. Thus, HBM had lower RC delay and higher performance of data processing than the conventional memory. Moreover, due to the development of the IT industry such as, AI (artificial intelligence), IOT (internet of things), and VR (virtual reality), the lower pitch size and the higher density were required to micro-electronics. Particularly, to obtain the fine pitch, some of the method such as copper pillar, nickel diffusion barrier, and tin-silver or tin-silver-copper based bump had been utillized. TCB (thermal compression bonding) and reflow process (thermal aging) were conventional method to bond between tin-silver or tin-silver-copper caps in the temperature range of 200 to 300 degrees. However, because of tin overflow which caused by higher operating temperature than melting point of Tin ($232^{\circ}C$), there would be the danger of bump bridge failure in fine-pitch bonding. Furthermore, regulating the phase of IMC (intermetallic compound) which was located between nickel diffusion barrier and bump, had a lot of problems. For example, an excess of kirkendall void which provides site of brittle fracture occurs at IMC layer after reflow process. The essential solution to reduce the difficulty of bump bonding process is copper to copper direct bonding below $300^{\circ}C$. In this study, in order to improve the problem of bump bonding process, copper to copper direct bonding was performed below $300^{\circ}C$. The driving force of bonding was the self-annealing properties of electrodeposited Cu with high defect density. The self-annealing property originated in high defect density and non-equilibrium grain boundaries at the triple junction. The electrodeposited Cu at high current density and low bath temperature was fabricated by electroplating on copper deposited silicon wafer. The copper-copper bonding experiments was conducted using thermal pressing machine. The condition of investigation such as thermal parameter and pressure parameter were varied to acquire proper bonded specimens. The bonded interface was characterized by SEM (scanning electron microscope) and OM (optical microscope). The density of grain boundary and defects were examined by TEM (transmission electron microscopy).

• Applied Microscopy
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• v.42 no.2
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• pp.87-93
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• 2012

In this study, fine structures of silica, titanium dioxide, talc and kaolin used in decorative cosmetics and the mixture extracted from BB cream cosmetics were observed by scanning electron microscopy. Kaolin had plate like shape structures of polygon with smooth surface and edge of kaolin had a relatively smooth appearance in comparison with talc. Also, thickness of each layer was estimated to about $0.1{\mu}M$ in the lump formed in stratum of several layers. Talc was observed by lumps shape phase of layering very thin flake. Boundary of thin flake was sharp or angular phase and thickness of flake was approximately 600 nm in diameter. When comparing the thickness of kaolin and talc, we was confirmed that kaolin was thicker than talc. Diameter of titanium dioxide was estimated to 0.2~0.3 ${\mu}M$ and surface of particle was a soft cubic form. Silica was confirmed that variety of size from 200 nm to $15{\mu}M$ of globular shape was measured. From the observation of inorganic pigments, silica was homogeneous dispersed in the BB cream cosmetics and among each other was filled with relatively small size like talc, kaolin, titanium dioxide and iron oxide. In conclusion, we suggest that silica at decorative cosmetics were formed in cosmetic coat at the skin as the minimum thickness.

• Korean Journal of Agricultural and Forest Meteorology
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• v.5 no.2
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• pp.138-149
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• 2003

Korean regional network of tower flux sites, KoFlux, has been initiated to better understand $CO_2$, water and energy exchange between ecosystems and the atmosphere, and to contribute to regional, continental, and global observation networks such as FLUXNET and CEOP. Due to heterogeneous surface characteristics, most of KoFlux towers are located in non-ideal sites. In order to quantify carbon and energy exchange and to scale them up from plot scales to a region scale, applications of various methods combining measurement and modeling are needed. In an attempt to infer regional-scale flux, four methods (i.e., tower flux, convective boundary layer (CBL) budget method, MM5 mesoscale model, and NCAR/NCEP reanalysis data) were employed to estimate sensible heat flux representing different surface areas. Our preliminary results showed that (1) sensible heat flux from the tower in Haenam farmland revealed heterogeneous surface characteristics of the site; (2) sensible heat flux from CBL method was sensitive to the estimation of advection; and (3) MM5 mesoscale model produced regional fluxes that were comparable to tower fluxes. In view of the spatial heterogeneity of the site and inherent differences in spatial scale between the methods, however, the spatial representativeness of tower flux need to be quantified based on footprint climatology, geographic information system, and the patch scale analysis of satellite images of the study site.