• The Journal of Korean Academy of Prosthodontics
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• v.42 no.2
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• pp.125-132
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• 2004

Statements of problem: All ceramic fixed partial denture cores can be made by the slip casting method and the advanced alumina tape method. The fracture resistance of these core connector areas is relatively low. Purpose: The purpose of this study is to standardize the appropriate volumetric figure and location of the connectors in the alumina core fabricated in alumina tape to be used in fixed partial dentures by way of topology optimization. Material and method: A maxillary anterior three-unit bridge alumina core with teeth form and surrounding periodontal apparatus model was used to ultimately design the most structurally rigid form of the connector. Loadings from a $0^{\circ}$, $45^{\circ}$ and $60^{\circ}$ to the axis of each tooth were applied and analyzed with the 3-D finite element analysis method. Using the results from these experiments, the topology optimization was applied and the optimal reinforcement layout of connector was obtained and the detail shape in the fixed partial denture core was designed. Results: The modified prosthesis with the form of a bulk in the lower lingual surface of the connector in the event, reduced the stress concentration up to 20% in the 3-D FEA. Conclusion: The formation of a bulk in the lower lingual connector area of an alumina core for a fixed partial denture decreases the stress to a clinically favorable measure but does not harm the esthetic point of view. This result illustrates the possibility of clinical application of the modified form designed by the topology optimization method.

• Journal of the Korean Ceramic Society
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• v.16 no.1
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• pp.13-20
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• 1979

High purity alumina has been extracted form low grade Korean alunite. Alunite ore was treated by 15% $NH_4OH$ solution, followed by 10% $H_2SO_4$ leaching and metallic impurities such as Fe and Ti were removed by solvent extraction method. Alumina prepared by the extraction process was 99.9% in purity. Hot Petroleum Drying Method has been employed for the preparation of uniformly fine alumina powder, using chemical reagent aluminum sulfate and ammonium aluminum sulfate extrated from Korea alunite. The sinterability of alumina powder prepared by Hot Petroleum Drying Method was shown to be improved in comparison with the one treated by other methods such as ball milling method, but dry pressing was difficult due to the agglomeration of calcined powder. The best slip of alumina powder prepared by Hot Petroleum Drying Method contained a lower soild content than the one treated by other methods. The alumina body formed by soild and drain casting with the former alumina powder showed a higher sintered density.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1993.04a
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• pp.27-34
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• 1993

Precast large panel structures behave differently form frame and monolithic wall structures under external loads, because of the distinct planes of weakness in the horizontal and vertical joints between panels. These joints may slide and open during shaking, producing large localized changes in the bending and shear stiffness of individual walls. The structural behavior of large precast panel buildings depends on the relative strength and stiffness of the panels and joints. Special modeling are thus required for the analysis of precast panel connections. This study suggests a new analytical modeling and method to obtain the rational estimation of discontinuity and slip movements form the connections of precast large panel structures .

• Bulletin of the Society of Naval Architects of Korea
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• v.12 no.1
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• pp.23-30
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• 1975

Because of the simplicity in analysis and design of steel structure, the connections of members are assumed either as perfectly hinged or rigidly fixed. However, a more economical design would result if the effect of restraint in connections were included in analyzing frame structure. From this point of view, stiffness matrices for member with bracketed connections are presented in the form of the stiffness matrices for member with variable moment of inertia, modified by a correction matrix, whose elements are functions of fixity factors of the connections. To obtain fixity factors, the displacements and stress distribution of bracketed connections are investigated by using of the degital computer program, which have been developed to make computing time shorten and the round off errors smaller. The relationship of moments and slip angle in bracketed connections are presented in the form of curves, which can be used in establishing a stiffness matrices for member with bracketed connections.

• Journal of the Korea Concrete Institute
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• v.13 no.6
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• pp.536-543
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• 2001

Nowadays, with high-stoned and large-sized of structures, high-strength concrete is applicable to various methods. When high-strength concrete is used jointly with system form, seizing on the development of compressive strength at early age is very important in aspect of construction process. Because system form is stripped more faster than ordinary form. But, we have little data of compressive strength before system-form is stripped, and it isn't yet established that decision criterion of the time when system-form is stripped. So this paper deals with the development of compressive strength at early age before system-form is stripped. In this study, the experimental results indicate the boundary of curing temperature and mixing factor that is able to get needful early-strength in the application of slip-form method, and curing temperature must be kept over 15 degrees in winter season.

• Journal of Industrial Technology
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• v.24 no.A
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• pp.239-250
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• 2004

Numerical analysis were performed to investigate the stability and internal movement of tunnel located beneath the base of abutment of bridge according to the method of supporting tunnel. Two supporting methods of the multi-staged grouting method with steel pipes and the large diameter of pipe supporting method were used in the centrifuge model tests. The slip form of model lining, specially built to simulate the process of tunnel excavating under the condition of accelerated g-level, was used in the centrifuge model tests. Four centrifuge model tests were performed, changing the supporting methods of the multi-staged grouting method with steel pipes and the large diameter of pipe supporting method and the location of model abutment base of bridge. For internal displacement of tunnel, movements of the crown. The left and the right sides of spring line were measured during the proceeds of excavating tunnel in centrifuge model tests. Test results were compared with numerically estimated values of internal displacement of tunnel by using the commercially available FEM software of PENTAGON-3D. It was found that they were in good agreements and the large diameter of pipe supporting method was more stable than the multi-staged grouting method with steel pipes with respect to the internal movement of tunnel.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• autumn
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• pp.255-266
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• 2000

Since 1993, Seohae grand bridge has been continued construction for 7 years and will be completed late this year. The bridge is a part of west sea castal highway and consists of 3 types of bridge including precast segmental method, free cantilever method and cable stayed bridge. A cable stayed bridge is the core of this bridge and it consists of 5 span, symetrical cable-stayed bridge with a total length of 990 m. The main span between two H-shaped pylons extending approximately 180 M above massive foundation of a cable stayed bridge is 470 m long and an approach span of that is 260 m long respectively. The circular cofferdam with 16 ea of 25 m diameter flat type sheet pile had been applied to construct foundation. The slipform method had been applied for forming of con'c of two H-shaped pylons with 3 cross beams respectively which is varied horizontally and vertically. The deck has been erected with balanced cantilever method using movable derrick crane. The stay cables is a bundle of parallel individually protected, 7 wire high tensile strands. The strands is hot deep galvanized and sheathed with a tight high density polyethylene coating. A petroleum wax fills all the inter-wire voids. The bundle of strands to prevent from deterioration due to the ambient problem covered with high density polyethylene pipe. The Isotension method has been applied for the stressing of cable strands to ensure uniformity of force in all the strands of a syay and such works has been performed on the stay specially provided in the pylon.

• Korean Chemical Engineering Research
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• v.57 no.4
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• pp.553-558
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• 2019

In present study, the cylindrical susceptor by the slip casting method was designed to apply high-temperature induction heating by using $(Mo,W)Si_2$ ceramics. $MoSi_2$-based materials were synthesized by SHS (Self-propagating High-temperature Synthesis) method. The phase and crystal structure of $MoSi_2$-based materials were confirmed by XRD analysis. The shape of cylindrical mold was synthesized for various thickness by using the slip casting method. Finally, the susceptor for induction heating was processed by sintering and heat treatment to form $SiO_2$ layer, which was confirmed on the surface of susceptor by SEM/EDS analysis. To evaluate the heating performance of $(Mo,W)Si_2$ cylinder susceptor, we measured the maximum surface temperature and heating rate in comparison with the rod heating element under constantly applied power. The induction heating of the $(Mo,W)Si_2$ cylinder showed excellent heating performance, reaches the maximum temperature of $1457^{\circ}C$, with the average heating rate of $19^{\circ}C/s$ at 2 kW

• Journal of the Korean Geosynthetics Society
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• v.18 no.4
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• pp.205-214
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• 2019

Load and resistance factor design of mound breakwater against circular failure was developed in this study. To achieve the goal, uncertainties of parameters of soils, mound, and concrete cap were determined. Eight design cases of domestic mound breakwaters were collected and analyzed. Monte Carlo Simulation was implemented to determine the most critical slip surfaces of the design cases. Using the results of Monte Carlo Simulation, First-Order Reliability Method (FORM) was used to perform reliability analyses. Optimal load and resistance factors were calculated using the reliability analysis results and final load and resistance factors were proposed based on the calculated optimal factors.

• Journal of Powder Materials
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• v.11 no.4
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• pp.288-293
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• 2004

The application concept of using a fail safety filter on the filtering system is to prevent the particle leakage when the main filter element is broken at high temperature. In this study, the metal filters were fabricated by pressureless sintering method. The mixture of stainless steel powders and filler metal binder solved in the water solutions of 5% PVA was compacted to form the cylindrical filter without pressure. The compacted filter were sintered in the vacuum sintering furnace at 120$0^{\circ}C$ for 1 hour. The metal filter(produced with powder of 640-840 ${\mu}m$ size) having more than above 50% porosity, 500${\mu}m$ pore size, and permeability of 7.3${\times}$10$^{-11}$m$^{2}$ plugged within 2.5 minute to prevent the leakage of maximum slip particle size of less than 3${\mu}m$.