• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.33 no.6
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• pp.654-659
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• 2007

We performed sinus bone graft using some amount of autogenous bone and $BioOss^{(R)}$ and covered the sinus window with $Ossix^{(R)}$ membrane in these case series. After 4 to 6 months after operation, histopathologic examinations of trephine core biopsy showed following results. 1. There were bone density of 39.2% to 41.2% four months after operation, and we could observe the favorable early new bone formation. 2. Active bony remodeling of woven and lamellar bone was observed during 4 to 6 months healing period. 3. There were no significant differences between two groups. And also there were no significant differences between 4 months and 6 months.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.4 s.235
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• pp.584-590
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• 2005

The effect of microstructure on mechanical behavior for Ti-6Al-4V alloy was studied. Two different kinds of specimens are prepared using heat treatments (rolled plate, $1050^{\circ}C)$ in order to Produce different microstructures. Various kinds of mechanical tests such as hardness, tensile, fatigue and fretting fatigue tests are performed for evaluation of mechanical properties with the changes of microstructures. Through these tests, the following conclusions are observed: 1) Microstructures are observed as equiaxed and $widmanst{\ddot{a}}ten$ microstructures respectively. 2) Impact absorbed energy is superior for the equiaxed microstructure, and the hardness and tensile strength are superior for the $widmanst{\ddot{a}}ten$ microstructure. 3) The fatigue endurance of $widmanst{\ddot{a}}ten$ microstritcture shows higher value than that of the equiaxed microstructure. 4) The fatigue endurance in fretting condition was reduced about $50{\%}$ from that of the non-fretting condition.

• Journal of Korea Foundry Society
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• v.8 no.4
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• pp.437-445
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• 1988

The effect of interlamellar spacing on microstructural stability at high temperature was studied for unidirectionally solidified ternary $Ni\;/\;Ni_3Al-Ni_3$ Nb and binary $Ni-Ni_3Nb$ eutectic composite. The interlamellar spacing of both alloy systems were varied with the growth rate according to $"{\lambda}^2R=constant"$ relationship. As a result of isothermal heat treatments at high temperature it was considered that coarsening of lamellar structure was due to concentration gradient between the tip with a relatively small radius of curvature and the side of the thick lamellae with a larger radius of the opposite sign. Fault density was increased as the interlamellar spacing decreased. Therefore it is also considered that the higher coarsening rate of the specimen with the smaller interlamellar spacing was due to higher fault density. And the diference of coarsening rate between $Ni\;/\;Ni_3Al-Ni_3Nb$ and $Ni-Ni_3Nb$ eutectic composites was not observed when the interlamellar spacing was similar in size. This means that the presence of ${\gamma}'$ in ${\gamma}\;/\;{\gamma}'\;-{\delta}$ eutectic had no b arrier effect to diffusion through the ${\gamma}$ matrix.

• Journal of Korea Foundry Society
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• v.40 no.2
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• pp.34-42
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• 2020

The effects of the initial balancing pressure, filling pressure and maximum build-up pressure on the casting characteristics of the thick-wall thickness casting during the counter-pressure casting process were investigated. Water model experiment and a computer simulation were carried out to evaluate the characteristics during the filling and solidification stages in counter-pressure casting (CPC); as a reference, the low-pressure casting (LPC) process was used. The average dendrite cell size decreased with an increase in the solidification rate and maximum build-up pressure. A turbulent flow occurred during the filling stage of the LPC process, resulting in the formation of inner gas, while a lamellar flow pattern dominated during the CPC process and was more evident with an increase in the initial balancing pressure, improving the mechanical properties of the castings.

• Journal of Power System Engineering
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• v.5 no.2
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• pp.63-70
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• 2001

To obtain the optimal condition of heat treatment of wear-resistant alloy, hardness and Charpy V-notch test have been performed with Co-based Stellite No.4, No.6 and Tribaloy 800 alloys, following by heat treatment at the various conditions. Heat treatment at $1250^{\circ}C$ for 1 hours caused the as-casted Tribaloy 800 with FCC crystal structure to transform to HCP structure and lamellar eutectic structure was disappeared, which did not influence on the hardness. Aging at $800^{\circ}C$ for 20 hours, following by $1250^{\circ}C$ for 2 hours heat treatment has enhanced hardness significantly, which is due to the precipitation of large amounts of Laves-phase. The hardness of Stellite alloys was increased by the aging at $800^{\circ}C$ to 5 hours, and was nearly constant by the aging over 5 hours. The toughness of Stellite alloys was a few influenced by the aging treatment.

• Korean journal of applied entomology
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• v.29 no.3
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• pp.157-164
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• 1990

The surface patterns and the structures of transverse section of the egg-shell of the sikmoth, Bombyx mandarina, have been described by scanning electron microscope. Three spatially differentiated cross section, called lamellar, conic pillar and cover layers, are found on the mature eg-shell. Silkmoth chorion proteins were detected more than 80 components from a single chorion by two-dimensional electrophoresis. Major protein components of the egg-shell have bee identified on the basis of their isoelectric points and molecular weights, pH 4-6 and 6-30 kd. Several protein components are found entirely or predominantly in th cover layers.

• Journal of the Korean Society for Heat Treatment
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• v.20 no.4
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• pp.195-202
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• 2007

Corrosion resistance and torque of M10 bolt coated with Magni 565 were investigated. Corrosion protection mechanism were also studied with the microstructure of coating film. The bolts with the optimum conditions showed around $10{\mu}m$ layer thickness, a great corrosion resistance in salt spray test and a proper torque in torque/tension test. But torque coefficient k increased with the number of bolting and clamping force of M10 bolt showed significantly lower than that of specified value 28.3kN. It was thought that the repeated bolting made the coating film peel off and powdery. The sample coated with optimum coating conditions showed more higher polarization resistance and corrosion potential than the specimens of top and base coat only. The base coating film was composed of lamellar zinc flakes, which provides a large sacrificial cathodic protection. Meanwhile, the top coating film was composed of organic aluminium pigments layer, which provides barrier protection to the corrosion circumstances.

• Applied Microscopy
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• v.17 no.1
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• pp.169-176
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• 1987

Naturally occurring canine transmissible venereal tumors of genital organs in mature and regressive stages from 6 dogs were examined by transmission electron microscope. The tumor cells at the stage of maturation were comprised of large round and ovoid cells with prominent nuclei and nucleoli, a few spindle-shaped cells, and irregularly shaped cells. The mature round cells were characterized by the presence of a central ovoid to irregularly round nucleus with a large eccentric nucleolus, vesicular endoplasmic reticulum, round to oval swollen mitochondria with few cristae, Golgi's apparatus, and plasma membranes with numerous microvilli. As the tumor degenerated, the tumor cells were increased in the number of spindle-shaped, fibroblast-like and irregularly shaped cells, collagen bundles, and mainly lymphocytes, in contrast to those of the stage of maturation. Regressing tumor cells were characterized by the swelling and vacuolation of mitochondria and endoplasmic reticulum, membrane-bound granules, lamellar complex, tubular structures, and dense bundles of collagen. It was suggested that transformation might occur in the course of tumor growth causing morphological change from the round to the fibroblast-like cells, and that there was the evidence of cell-mediated tumor cell lysis by lymphocyte infiltration.

• The Journal of Korean Academy of Prosthodontics
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• v.29 no.2
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• pp.35-48
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• 1991

Installation periods of implants in Mx. and Mn., is related to pattern of bone formation. The purpose of this study was to observe histologic response in osseointegration at root formed implant-tissue interface at Mx. and Mn., the other is comparison of osseointegration level between Mx. and Mn. at 8 weeks. In this study, unilateral upper & lower molars were extracted in dog. After allowing to heal for 4 months, two kinds of osseointegrated implants Swedevents, Corevents-were inserted in dog. The specimens were treated by conventional method. The interface zones between bone and implant were investiigated using X-rays, light microscope. The following results were obtained from this study. 1. Around titanium implants that were installed in Ma and Mn., Radio lucencies don't exist 2. There are not inflammation and mobility of titanium implants that were installed in Mx. and Mn. Most of implant surface are covered by bony tissued partly by bone-marrow tissues. 3. Titanium implants installed in Mx, in contrast to same implants in Mn., shows more coverage by bone marrow tissue and lack of apposition lamellar bone, which lead to the assumption that bone formation in Mn. is faster than in Mx.

• Journal of Korea Foundry Society
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• v.25 no.1
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• pp.30-35
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• 2005

The structures and mechanical property of the unidirectionally solidified Al-Co eutectic alloy were investigated. Al-Co eutectic alloy was unidirectionally solidified with growth rates(R) between I cm/hr and 10 cm/hr in the induction furnace maintaining the thermal gradient (G) at solid-liquid interface, $32^{\circ}C$/cm. The eutectic microstructure was varied with the growth condition(G/R ratio). When the G/R ratio was larger than $8.5{\times}10^{3}^{\circ}C/cm^{2}/sec$, a lamellar structure was formed, But the G/R ratio was smaller than $8.5{\times}10^{3}^{\circ}C/cm^{2}/sec$, a colony structure was formed. It was found that the interlamellar spacing(${\lambda}$) was dependent on the growth rate(R) with the relationship, ${\lambda}^{2}{\cdot}R=constant$. The microhardness of this eutectic alloy increased with increase in the growth rate.