• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.10 no.1
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• pp.82-89
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• 2014

In this study, the metallurgical analysis and mechanical property measurement have been performed to investigate the effect of long-term thermal aging on the microstructural evolution in the fusion boundary region between weld metal and low alloy steel in dissimilar metal welds. A representative dissimilar weld mock-up made of Alloy 690-Alloy 152-A533 Gr. B was fabricated and aged at $450^{\circ}C$ for 2,750 hours. The microstructural characterization was conducted mainly near in a weld root region by using optical microscopy, scanning electron microscopy, transmission electron microscopy. And the mechanical properties were measured with Vickers microhardness test and nanoindentation method. A steep gradient was shown in the chemical composition profile across the interface between A533 Gr. B and Alloy 152. Type-II boundaries were found in weld side of DMW and the hardness was the highest at the narrow zone between Type-II boundary and fusion boundary.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.26 no.6
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• pp.225-231
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• 2016

The valence band maximum (VBM) and conduction band minimum (CBM) of Al-doped GaInAsSb alloys substrated on GaSb are calculated by using an analytic approximation based on the tight binding method. The relative positions of the VBM and CBM between Al-GaInASSb and GaSb determine band alignement type, valence band offset (VBO) and conductin band offset (CBO) for the heterojunctions. In this study, aluminium doping is assumed to be substituted in the cation site and limited up to 20 % because it can easily oxidize and degrade materials. It is found that the Al-doped alloys exhibit type-II band alignments over the entire composition range and make the band gaps increase, whereas the VBO and CBO decrease. The decreasing rate of VBO is higher than that of CBO, which implies the Al components play a decisive role in controlling electrons at the interface. The Al-dopled GaInAsSb alloy has a direct band gap induced by $E({\Gamma})$ with a considerable distance from the E(L) and E(X), however, $E({\Gamma})$ approaches to E(L) and E(X) in the high Sb concentration (Sb > 0.7-0.8) which might affect the electron mobility and degrade the optical quality.

• Journal of the Korean Vacuum Society
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• v.20 no.6
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• pp.461-467
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• 2011

The valence band maximum and the conduction band miminum of GaAs, GaSb, InAs, and InSb (constituent binaries of the quaternaty alloy $Ga_xIn_{1-x}Sb_yAs_{1-y}$) are calculated by using TB analytical approach method. The band alignment types of their heterojunctions are determined directly from their relative position of band edges (VBM and CBM). For example, the GaAs/InAs, GaAs/InSb, and GaSb/InSb are in a type-I, the GaAs/GaSb in a type-II, and the GaSb/InAs and InSb/InAs in a type-III, respectively. The composition dependent VBM and CBM for the $Ga_xIn_{1-x}Sb_yAs_{1-y}$ alloy are obtained by using the univeral tight binding method. For the alloyed heterojunctions, the band alignments can be controlled by changing the composition which induce a band type transition. For the alloy $Ga_xIn_{1-x}Sb_yAs_{1-y}$ lattice mathced to GaSb, the type-II band alignment in the region of $x{\leq}0.15$ is changed to the type-III in the region of $x{\geq}0.81$. On the other hand, the alloy $Ga_xIn_{1-x}Sb_yAs_{1-y}$ lattice mathced to InAs has the type-II band alignment in the region of $x{\leq}0.15$ and the type-III band alignment in the region of $x{\geq}0.81$, respectively.

• Journal of Biomedical Engineering Research
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• v.24 no.5
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• pp.401-410
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• 2003

This study investigates the biomechanical efficacies of various cement augmentation techniques with or without pressurization for varying degrees of osteoporotic femur. For this study, a biomechanical analysis using a finite element method (FEM) was undertaken to evaluate surgical procedures, Simulated models include the non-cemented(i.e., hip screw only, Type I), the cement-augmented(Type II), and the cemented augmented with pressurization(Type III) models. To simulate the fracture plane and other interfacial regions, 3-D contact elements were used with appropriate friction coefficients. Material properties of the cancellous bone were varied to accommodate varying degrees of osteoporosis(Singh indices, II∼V). For each model. the following items were analyzed to investigate the effect surgical procedures in relation to osteoporosis of varying degrees : (a) von Mises stress distribution within the femoral head in terms of volumetric percentages. (b) Peak von Mises stress(PVMS) within the femoral head and the surgical constructs. (c) Maximum von Mises strain(MVMS) within the femoral head, (d) micromotions at the fracture plane and at the interfacial region between surgical construct and surrounding bone. Type III showed the lowest PVMS and MVMS at the cancellous bone near the bone-construct interface regardless of bone densities. an indication of its least likelihood of construct loosening due to failure of the host bone. Particularly, its efficacy was more prominent when the bone density level was low. Micromotions at the interfacial surgical construct was lowest in Type III. followed by Type I and Type II. They were about 15-20% of other types. which suggested that pressurization was most effective in limiting the interfacial motion. Our results demonstrated the cement augmentation with hip screw could be more effective when used with pressurization technique for the treatment of intertrochanteric fractures. For patients with low bone density. its effectiveness can be more pronounced in limiting construct loosening and promoting bone union.

• Water for future
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• v.29 no.2
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• pp.143-151
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• 1996

The dynamic responses in the subsurface outflow, surface saturation area, soil moisture storage are established by numerical experiments with Richards equation. In addition to this, the dynamical relationship between surface saturation area and subsurface outflow, and between surface saturation area and soil moisture storage are also determined by varying the hillslope shape, soil type, and boundary condition. The simulation results indicate that the dynamical relationships between surface saturation area and subsurface outflow, and between surface saturation area and soil moisture storage are approximated by the steadystate relationships. And the dynamic responses of subsurface outflow and surface saturation area are characterized by the double peaks although the rainfall pattern is asimple pulse input. As a result of numerical simulation, the physical mechanism for the occurrence of the double peaks is explained using the concept of variable source area.

• Journal of the korean academy of Pediatric Dentistry
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• v.31 no.4
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• pp.651-658
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• 2004

Runx2 is a transcription factor in homologous with Drosophila runt gene and it is essential for bone formation during embryogenesis and a critical gene for osteoblast differentiation and osteoblast function. Runx2-haploinsufficency causes cleidocranial dysplasia (CCD). CCD is an autosomal-dominant inherited disorder characterized by hypoplastic clevicle and delayed ossification in fontanelles and wormian bones. Dental defects are possibly shown to CCD patients : multiple supernumerary teeth, irregular and compressed permanent tooth crowns, hypoplastic and hypomineralized defects in enamel and dentin, an excess of epithelial root remnants, the absence of cellular cementum, and abnormally shaped roots. In addition, delayed eruption of the secondary dentition is a constant finding. The aim of this study is to evaluate the role of Runx2 in the tooth development and eruption through analyzing the expression pattern of Runx2 by in situ hybridization during crown (late bell stage) and root formation of tooth, using postnatal day 1, 4, 7, 14 and 21 mice mandibular molar teeth. mRNA of Runx2-full length is expressed in dental follicle and surrounding tissue at postnatal day1 and 4. At postnatal day 7, it is expressed in ameloblasts of occlusal surface of enamel and bone area surrounding the tooth. In comparison with previous stage, at postnatal day 14, it is expressed in ameloblasts of proximal surface of enamel. At postnatal day 21 it's expression is observed only in bone area. mRNA of Runx2-typeII is not expressed. At postnatal day 1 and 7. At postnatal day 14 and 21, it's expression is observed in the bone area. In this study, we suggest that Runx2 have a relation of ameloblasts differentiation and an important role to tooth eruption made by dental follicle during intraosseous eruption stage. Also we can confirm that Runx2 has a role to bone formation.

• Journal of Dental Rehabilitation and Applied Science
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• v.16 no.1
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• pp.51-60
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• 2000

The purpose of this study was to compare the microleakage at the interface of cast post and tooth according to the type of cement. Forty anterior teeth with single root were used. The teeth were cut 2 mm coronal from the cementoeamel junction and chamfer finish line was made on 1 mm coronal from the cementoeamel junction. After the routine endodontic treatment, post space was prepared using #5.5 Parapost drill to a depth of 7 mm. After the pick up impression, core building was made to 3 mm of clinical crown with burnout wax, then post and core was cast with nonprecious metal. The teeth were divided into four groups of ten each. In Group I, post and core were cemented with Fleck's(Zinc phosphate cement) In Group II, post and core were cemented with Fuji I(Glass ionomer cement) In Group III, post and core were cemented with Superbond C & B(Composite resin cement) In Group IV, post and core were cemented with Panavia 21(Composite resin cement) All cemented teeth were stored in normal saline at $37^{\circ}C$ for 7 days and thermocycled from $5^{\circ}C$ to $55^{\circ}C$ for 500 cycles with a dwell time of 30 seconds. After thermocycling, teeth were immersed in 1% Basic fuchsin dye for 48 hours. All 40 teeth were then embedded in the epoxy resin and cut buccolingually with a cutting instrument. The degree of penetration of dye at interface was graded on a scale of 0 to 4 using a stereomicroscope at 25 to 40 times magnification. Through the findings of this study, the following conclusion were obtained. 1. All the groups showed the microleakage at the interface of cast post core and tooth. 2. Group I showed the highest microleakage score among the groups with a significant difference(p<0.05). 3. Group II showed higher microleakage score than Group III and Group IV with a significant difference(p<0.05). 4. Group IV showed the lowest microleakage score but there were no significant difference with Group III(p>0.05).

• Journal of the korean academy of Pediatric Dentistry
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• v.27 no.1
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• pp.1-6
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• 2000

Dentinogenesis imperfecta is an inherited disorder of dentin formation, usually exhibiting an autosomal dominant mode of transmission. Type I dentinogenesis imperfecta occurs in patients afflicted with osteogenesis imperfecta. Type II dentinogenesis imperfecta is not associated with osteogenesis imperfecta. Type III dentinogenesis imperfecta (Brandywine type) occurs in a racial isolate area in the state of Maryland. In all three types, teeth of both dentitions are affected with variable clinical appearances. The teeth are opalescent with the color ranging from bluish-gray to brown to yellowish. The dentin is abnormally soft, providing inadequate functional support to the overlying enamel. Although the enamel is normal, it fractures or chips away easily, exposing the occlusal and incisal dentin. The exposed soft dentin often undergoes rapid and severe functional attrition. The teeth exhibit bulb-shaped crowns with constricted cementoenamel junctions and thin roots. The teeth will exhibit varying stages of obliteration of the coronal and root pulpal chambers. The cementum, periodontal ligament and supporting alveolar bone appear normal. The enamel is normal. The mantle dentin remains nearly normal, whereas the remaining dentin is severely dysplastic. The dentinal tubules are disoriented, irregular, widely spaced, and usually larger than normal.

• The Journal of the Petrological Society of Korea
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• v.20 no.1
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• pp.39-59
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• 2011

To get the geologic information data such as rock resources, industrial ground, development planning and so on, distribution ratios of constituent rocks with geologic age and rock type were obtained in Gyeongnam, Ulsan and Busan areas by ArcGIS 9.3 program, digital geologic and geomorphic maps of 1 : 250,000 scale. Geologic ages and rock types in the Gyeongnam area can be divided into 6 and 40, respectively. Their distribution ratios of the geologic ages are decreasing in the order of Cretaceous, Precambrian, Quaternary, Jurassic, Triassic and Tertiary. They show the wide ranges of 1.35-57.36%, and the former makes the most dominant ratio. Major rock types are 24 ones, all of which occupy the ratio of 94.58% and relatively narrow ranges of 1.15-13.64% in the area. Among them, andesite and andesitic tuff shows the more or less dominant ratio, and separately develops in the northeast, mid east and south parts of the area. In the Ulsan area, geologic ages and rock types can be divided into 3 and II, respectively. Their distribution ratios of the geologic ages are decreasing in the order of Cretaceous, Quaternary and Triassic. They show the very wide range of 6.90-79.21%, and the former makes the most prevailing ratio. Major rock types are 9 ones, which totally occupy the ratio of 98.63% and more or less wide ranges of 1.50-39.01% in the area. Among them, Jindong formation shows the most dominant ratio, and widely develops in the inner and eastern part of the area. In the Busan area, geologic ages and rock types can be divided into 3 and 10, respectively. Their distribution ratios of the geologic ages are decreasing in the order of Cretaceous, Quaternary and Tertiary. They show the wide ranges of 6.73-47.02%, and the two former makes the most dominant ratio of 88.03%. Major rock types are 6 ones, all of which occupy the ratio of 93.02% and relatively wide ranges of 4.07-47.02% in the area. Among them, alluvium forms the most dominant ratio, which mostly develops in the lower Nagdong River, West Nagdong River and Suyeong River.

• Journal of Technologic Dentistry
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• v.21 no.1
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• pp.27-41
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• 1999

The Ag-Pd-Cu alloys containing a small amount of Au is commonly used for dental purposes, because this alloy cheaper than Au-base alloys for clinical use. However, the most important characteristic of this alloy is age-hardenability, which is not exhibited by other Ag-base dental alloys. The specimens used were Ag-30Pd-10Cu ternary alloy and Au addition alloy. These alloys were melted and casted by induction electric furnace and centrifugal casting machine in Ar atmosphere. These specimens were solution treated for 2hr at $800^{\circ}C$ and were then quenched into iced water, and aged at 350-$550^{\circ}C$ Age-hardening characteristic of the small Au-containing Ag-Pd-Cu dental alloys were investigated by means of hardness testing, X-ray diffraction and electron microscope observations, electrical resistance, differential scanning calorimetric, energy dispersed spectra and electron probe microanalysis. Principal results are as follows ; Maximum hardening occured in two co-phases of ${\alpha}_2$ + PdCu In stage II, decomposition of the $\alpha$ solid solution to a PdCu ordered phase($L1_o$ type) and an Ag-rich ${\alpha}_2$ phase occurred and a discontinuous precipitation occurred at the grain boundary. From the electron microscope study, it was concluded that the cause of age-hardening in this alloy is the precipitation of the PdCu redered phase, which has AuCu I type face-centered tetragonal structure. Precipitation procedure was ${\alpha}{\to}{\alpha}_1+PdCu{\to}{\alpha}_2+PdCu$ at Pd/Cu = 3 Pd element of Ag-Pd-Cu alloy is more effective dental alloy on anti-corrosion and is suitable to isothermal ageing at $450^{\circ}C$.