• Journal of the Korean GEO-environmental Society
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• v.13 no.3
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• pp.29-37
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• 2012

This study is to find out the characteristics of the behavior of Geosyntehtic Reinforced Retaining Earth Wall(GRREW) through the laboratory experiment with the reduced-scale model, and to verify the effect of reinforcement by materials of GRREW. The loading tests after combining nonwoven geosynthetic, re-bar mesh nets and drainage blocks respectively among the components of the GRREW were performed in three cases of their slopes. In the cases of the behavior analysis including all of the components of the GRREW, the maximum horizontal displacement was generated 8.4mm at the location of 0.57H in the slope of 1:0.3; 3.8mm at the location of 0.57H in the slope of 1:0.6; 3.6mm at the location of 0.86H in the slope of 1:1.0. On average, the horizontal displacements of the GRREW were reduced by 83.8% against those of the original slopes. Lastly, seepage analysis and slope stability analysis were performed by modelling section of field, to confirm the effect of installation of drainage block in GRREW. We can confirm to compare increasing the slope safe factor and decreasing ground water in accordance with drainage blocks.

• The Journal of Korean Academy of Prosthodontics
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• v.44 no.3
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• pp.295-313
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• 2006

Statement of problem. Higher fracture rates were reported for Branemark implants placed in the maxilla and for 3.75 mm diameter implants installed in the posterior region. Purpose. The purpose of this study was to investigate the fracture of a fixture by finite element analysis and to compare different diameter of fixtures according to the level of alveolar bone resorption. Material and Methods. The single implant and prosthesis was modeled in accordance with the geometric designs for the 3i implant systems. Models were processed by the software programs HyperMesh and ANSA. Three-dimensional finite element models were developed for; (1) a regular titanium implant 3.75 mm in diameter and 13 mm in length (2) a regular titanium implant 4.0 mm in diameter and 13 mm in length (3) a wide titanium implant 5.0 mm in diameter and 13 mm in length each with a cementation type abutment and titanium alloy screw. The abutment screws were subjected to a tightening torque of 30 Ncm. The amount of preload was hypothesized as 650 N, and round and flat type prostheses were 12 mm in diameter, 9 mm in height were loaded to 600 N. Four loading offset points (0, 2, 4, and 6 mm from the center of the implants) were evaluated. To evaluate fixture fracture by alveolar bone resorption, we investigated the stress distribution of the fixtures according to different alveola. bone loss levels (0, 1.5, 3.5, and 5.0 mm of alveolar bone loss). Using these 12 models (four degrees of bone loss and three implant diameters), the effects of load-ing offset, the effect of alveolar bone resorption and the size of fixtures were evaluated. The PAM-CRASH 2G simulation software was used for analysis of stress. The PAM-VIEW and HyperView programs were used for post processing. Results. The results from our experiment are as follows: 1. Preload maintains implant-abutment joint stability within a limited offset point against occlusal force. 2. Von Mises stress of the implant, abutment screw, abutment, and bone was decreased with in-creasing of the implant diameter. 3. With severe advancing of alveolar bone resorption, fracture of the 3.75 and the 4.0 mm diameter implant was possible. 4. With increasing of bending stress by loading offset, fracture of the abutment screw was possible.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.7
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• pp.441-448
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• 2016

The thrust force created by a propeller depends on the incoming flow velocity and the rotational velocity of the propeller. The performance of the propeller can be described by dimensionless variables, advanced ratio, thrust coefficient, and power coefficient. This study included the application of the immersed boundary lattice Boltzmann method (IBLBM) with the stereo lithography (STL) file of the rotating object for performance analysis. The immersed boundary method included the addition of the external force term to the LB equation defined by the velocity difference between the lattice points of the propeller and the grid points in the domain. The flow by rotating a 4-blade propeller was simulated with various Reynolds numbers (Re) (including 100, 500 and 1000), with advanced ratios in the range of 0.2~1.4 to verify the suggested method. The typical tendency of the thrust efficiency of the propeller was obtained from the simulation results of different advanced ratios. It was also necessary to keep the maximum mesh size ratio of the propeller surface to a grid size below 3. Additionally, a sufficient length of the downstream region in the domain was maintained to ensure the numerical stability of the higher Re and advanced ratio flow.

• Korean Chemical Engineering Research
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• v.48 no.2
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• pp.172-177
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• 2010

This study reports the high-temperature oxidation kinetics, ASR(area specific resistance), and interfacial microstructure of metallic interconnects coated with conductive oxides in oxidation atmosphere at $800^{\circ}C$, The conductive material LSC($La_{0.8}Sr_{0.2}CoO_3$, prepared by Solid State Reaction) was coated on the Crofer22APU. The contact behavior of coating layer/metal substrate was increased by sandblast. The electrical conductivity of the LSC coated Crpfer22APU was measured by a DC two probe four wire method for 4000hr, in air at $800^{\circ}C$. Microstructure and composition of the coated layer interface were investigated by SEM/EDS. These results show that a coated LSC layer prevents the formation and growth of oxide scale such as $Cr_2O_3$ and enhances the long-term stability and electrical performance of metallic interconnects for SOFCs.

• Toxicological Research
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• v.30 no.4
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• pp.305-309
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• 2014

Recently, there has been an increase in the use of several nephrotoxicity biomarkers in preclinical experiments. In addition, it has been indicated that the result may have been influenced by secondary factors, such as sample storage condition or storage period. In this study, we have assessed the variation in urinary nephrotoxicity biomarkers as a result of urine storage conditions and storage period of the urine. Urine was sampled from specific pathogen-free Sprague-Dawley rats (19 weeks old), which were housed individually in hanged stainless steel wire mesh cages. Urine was stored at $20^{\circ}C$, at $4^{\circ}C$, or at $-70^{\circ}C$ after sampling. The levels of the biomarkers such as beta-2 microglobulin (B2M), cystatin-C (Cys-C), N-acetyl-${\beta}$-D-glucosaminidase (NAG), micro albumin (MA), micro protein (MP) were measured at 6, 24, 48 and 144 hr after sampling. The B2M level was significantly decreased at 6, 24, 48, and 144 hr compared to 0 hr at $-70^{\circ}C$ (p < 0.05, p < 0.01, p < 0.05, and p < 0.05, respectively) and 24 and 144 hr at $20^{\circ}C$ (p < 0.01, p < 0.01, respectively). The Cys-C level was significantly decreased at 144 hr compared to 0 hr at $4^{\circ}C$ (p < 0.01), at $20^{\circ}C$ (p < 0.05) and at $70^{\circ}C$ (p < 0.01). MP and MA levels were not different for 144 hr in all storage conditions. Taken together, B2M and Cys-C levels were modulated by storage temperature and period. For the enhancement of test accuracy, it is suggested that strict protocols be established for samples to minimize the effects of the storage conditions on the detected levels of biomarkers.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.7
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• pp.1244-1251
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• 2022

Marine accidents due to a loss of stability, have been gradually increasing over the last decade. Measures must be taken on the roll reduction of a ship. Amongst the measures, building an anti-roll tank in a ship is recognized as the most simple and effective way to reduce the roll motion. Therefore, this study aims to develop a computational model for a U-tube type anti-roll tank and to validate it by experiment. In particular, to validate the developed computational model, the height of the free surface in the tank was measured in the experiment. To develop a computational model, the mesh dependency test was carried out. Further, the effects of a turbulence model, time step size, and the number of iterations on the numerical solution were analyzed. In summary, a U-tube type anti-roll tank simulation had to be performed accurately with conditions of a realizable k-𝜖 turbulence model, 10^-2s time step size, and 15 iterations. In validation, the two cases of measured data from the experiment were compared with the numerical results. In the present study, STAR-CCM+ (ver. 17.02), a RANS-based commercial solver was used.

• Journal of Adhesion and Interface
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• v.25 no.1
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• pp.169-274
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• 2024

Recent attention has been drawn to materials that undergo reversible expansion and contraction in response to external stimuli, leading to morphological changes. These materials hold potential applications in various fields including soft robotics, sensors, and artificial muscles. In this study, a novel material capable of responding to high temperatures for protection or encapsulation is proposed. To achieve this, liquid crystal elastomer (LCE) with nematic-isotropic transition properties and polyimide (PI) with high mechanical strength and thermal stability were utilized. To utilize a solution process, a dope solution was synthesized and introduced into micro-printing techniques to develop a two-dimensional pattern of LCE/PI bilayer structures with sub-millimeter widths. The honeycomb-patterned LCE/PI bilayer mesh combined the mechanical strength of PI with the high-temperature contraction behavior of LCE, and selective printing of LCE facilitated deformation in desired directions at high temperatures. Consequently, the functionality of selectively and reversibly encapsulating specific high-temperature materials was achieved. This study suggests potential applications in various actuator fields where functionalities can be implemented across different temperature ranges without the need for electrical energy input, contingent upon molecular changes in LCE.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.20 no.1
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• pp.41-51
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• 1987

This study was carried out to prepare powdered smoked-dried mackerel which can be used as a soup base, and to examine storage stability and the taste compounds of Products. Raw mackerel are filleted, toiled for 10 minutes and pressed to remove lipids, and then soaked in extract solution of skipjack meat. This soaked mackerel are smoked 3 times to $10-12\%$ moisture content at $80^{\circ}C$ for 8 hours. And the smoked-dried mackerel were pulverized to 50 mesh. Finally, the powdered smoked-dried mackerel were packed in a laminated film $bag(PET/Al\;foil/CPP:\;5{\mu}m/15{\mu}m/70{\mu}m,\;15\times17cm)$ with air(product C), nitrogen(product N) and oxygen absorber(product O), and then stored at room temperature for 100 days. The moisture and crude lipid content of powdered smoked-dried mackerel was $11.3-12.3\%,\;12\%$, respectively, and water activity is 0.52-0.56. And these values showed little changes during storage. The pH, VBN and amino nitrogen content increased slowly during storage. Hydrophilic and lipophilic brown pigment formation showed a tendency of increase in product(C) and showed little change in product(N) and (O). The TBA value, peroxide value and carbonyl value of product(N) and (O) were lower than those of product (C). The major fatty acids of products were 16:0, 18:1, 22:6, 18:0 and 20:5, and polyenoic acids decreased, while saturated and monoenoic acids increased during processing and storage of products. The IMP content in products were 420.2-454.2 mg/100 g and decreased slightly with storage period. And major non-volatile organic acids in products were lactic acid, succinic acid and $\alpha-ketoglutaric$ acid. In free amino acids and related compounds, major ones are histidine, alanine, hydroxyproline, lysine, glutamic acid and anserine, which occupied $80.8\%$ of total free amino acids. The taste compounds of powdered smoked-dried mackerel were free amino acids and related compounds (1,279.4 mg/100 g), non-volatile organic acids(948.1 mg/100 g), nucleotides and their related compounds (672.8 mg/100 g), total creatinine(430.4 ntg/100 g), tetaine(86.6 mg/100 g) and small amount of TMAO. The extraction condition of powdered smoked-dried mackerel in preparing soup stock is appropriate at $100^{\circ}C$ for 1 minute. Judging from the results of taste and sensory evaluation, it is concluded that the powdered smoked-dried mackerel can be used as natural flavoring substance in preparing soups and broth.

• Electrical & Electronic Materials
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• v.12 no.7
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• pp.7-11
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• 1999

Fully sealed field emission display in size of 4.5 inch has been fabricated using single-wall carbon nanotubes-organic vehicle com-posite. The fabricated display were fully scalable at low temperature below 415$^{\circ}C$ and CNTs were vertically aligned using paste squeeze and surface rubbing techniques. The turn-on fields of 1V/${\mu}{\textrm}{m}$ and field emis-sion current of 1.5mA at 3V/${\mu}{\textrm}{m}$ (J=90${\mu}{\textrm}{m}$/$\textrm{cm}^2$)were observed. Brightness of 1800cd/$m^2$ at 3.7V/${\mu}{\textrm}{m}$ was observed on the entire area of 4.5-inch panel from the green phosphor-ITO glass. The fluctuation of the current was found to be about 7% over a 4.5-inch cath-ode area. This reliable result enables us to produce large area full-color flat panel dis-play in the near future. Carbon nanotubes (CNTs) have attracted much attention because of their unique elec-trical properties and their potential applica-tions [1, 2]. Large aspect ratio of CNTs together with high chemical stability. ther-mal conductivity, and high mechanical strength are advantageous for applications to the field emitter [3]. Several results have been reported on the field emissions from multi-walled nanotubes (MWNTs) and single-walled nanotubes (SWNTs) grown from arc discharge [4, 5]. De Heer et al. have reported the field emission from nan-otubes aligned by the suspension-filtering method. This approach is too difficult to be fully adopted in integration process. Recently, there have been efforts to make applications to field emission devices using nanotubes. Saito et al. demonstrated a car-bon nanotube-based lamp, which was oper-ated at high voltage (10KV) [8]. Aproto-type diode structure was tested by the size of 100mm $\times$ 10mm in vacuum chamber [9]. the difficulties arise from the arrangement of vertically aligned nanotubes after the growth. Recently vertically aligned carbon nanotubes have been synthesized using plasma-enhanced chemical vapor deposition(CVD) [6, 7]. Yet, control of a large area synthesis is still not easily accessible with such approaches. Here we report integra-tion processes of fully sealed 4.5-inch CNT-field emission displays (FEDs). Low turn-on voltage with high brightness, and stabili-ty clearly demonstrate the potential applica-bility of carbon nanotubes to full color dis-plays in near future. For flat panel display in a large area, car-bon nanotubes-based field emitters were fabricated by using nanotubes-organic vehi-cles. The purified SWNTs, which were syn-thesized by dc arc discharge, were dispersed in iso propyl alcohol, and then mixed with on organic binder. The paste of well-dis-persed carbon nanotubes was squeezed onto the metal-patterned sodalime glass throuhg the metal mesh of 20${\mu}{\textrm}{m}$ in size and subse-quently heat-treated in order to remove the organic binder. The insulating spacers in thickness of 200${\mu}{\textrm}{m}$ are inserted between the lower and upper glasses. The Y\ulcornerO\ulcornerS:Eu, ZnS:Cu, Al, and ZnS:Ag, Cl, phosphors are electrically deposited on the upper glass for red, green, and blue colors, respectively. The typical sizes of each phosphor are 2~3 micron. The assembled structure was sealed in an atmosphere of highly purified Ar gas by means of a glass frit. The display plate was evacuated down to the pressure level of 1$\times$10\ulcorner Torr. Three non-evaporable getters of Ti-Zr-V-Fe were activated during the final heat-exhausting procedure. Finally, the active area of 4.5-inch panel with fully sealed carbon nanotubes was pro-duced. Emission currents were character-ized by the DC-mode and pulse-modulating mode at the voltage up to 800 volts. The brightness of field emission was measured by the Luminance calorimeter (BM-7, Topcon).

• Maxillofacial Plastic and Reconstructive Surgery
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• v.31 no.5
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• pp.365-374
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• 2009

Purpose : This research evaluates the effect of the use of absorbable membrane barrier with deproteinized bovine bone (Bio-$Oss^{(R)}$, Switzerland) on bone healing in surgically created critical-sized defects in rat calvaria. Materials and Methods : Two standardized transosseous circular calvarial defects (5 mm in diameter) are made in each calvarium of 30 rats. These rats are divided into negative control group(n=15), positive control group(n=15) and two experimental groups(n=15). In the negative control group, defects are only filled with blood clots. In the positive control group, defects are filled with autogenous bone obtained from calvarium; in the experimental group 1, defects are filled with deproteinized bovine bone; and in the experimental group 2, defects are filled with deproteinized bovine bone with absorbable membrane. At the postoperative 1 week, 3 weeks. and 6 weeks, clinical. histologic and histomorphometric evaluations of the defects are performed. Results : 1. The grafted bone without membrane in the calvarial bone defect was scattered but, the grafted bone with membrane was stable. 2. $BioMesh^{(R)}$ membrane was absorbed beginning at 3 weeks, and was absorbed considerably at 6 weeks while maintaining the structural form of the membrane. 3. The use of membrane blocked soft tissue invasion. 4. In histomorphometric analysis. it showed the greatest amount of new bone formation in the positive control group. The amount of new bone formation was greater in the experimental group 2 than experimental group 1. At 6 weeks. the amount of new bone formation was greater in the positive control group than experimental group l(p<0.005). Conclusion : These results suggest that membrane increase the stability of grafted bone and protects from soft tissue invasion, and the use of the membrane may promote new bone formation in deproteinized bovine bone graft area.