• Journal of Welding and Joining
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• v.6 no.4
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• pp.1-6
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• 1988

아크용접에 로보트가 적용되면서 그 적용대상 폭을 넓히기 위하여 여러 종류의 센서들이 개발되어 왔다. 그 중 로보트나 자동용접장치에 장착이 용이한 아크센서에 대하여 원리들과 응용한 예들을 소개하였다. 용접이음부의 최소두께 제한, 용접중 용융지의 처침(Distortion) 등에 따른 아크신호의 불안정이 문제로 남아 있으므로 아크센서의 신뢰도를 향상시키기 위해서는 각 용접공정의 보다 정확한 해석이 요구되며, 이들을 적용하기 위한 제어 알고리즘의 개선 또한 요구된다. 아크센서가 개선되어 신뢰도가 높아질수록 더욱 광범위하게 적용될 것이며, 아크용접작업의 생산성 향상에 크게 기여하게 될 것이다.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.1
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• pp.150-157
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• 1997

Uniform weld pool shape is important in determining the weld quality. And weld pool width is one of the most dominant factors of the seld pool shape. In order to control the weld pool width, the fuzzy logic controller, which is well adapted to the complicated nonlinear systems such as welding, was used in this study. The weld pool image was obtained through CCD camera, and the weld pool width was calculated by processing the image. Uaing the calculated width, welding speed, as a control input, was inferred by the fuzzy logic controller. An uniform weld pool width can be successfully obtained regardless of the disturbances in the system.

• Applied Chemistry for Engineering
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• v.10 no.1
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• pp.118-123
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• 1999

The recycle of the polycarbonate(PC)/acrylonitrile-butadiene-styrene(ABS) separated from the instrument panel (In-Panel) of the automotive was investigated. The small amount of polyurethane(PU) foam contained in the separated PC/ABS decreased the mechanical properties of the recycled PC/ABS. However, it is found that the PU foam formed the dispered phase of small particles at high temperature ($260^{\circ}C$) under high shear of the twin extruder, whereas it formed the big particles at low extrusion temperature ($220^{\circ}C$). The mechanical properties of the recycled PC/ABS extruded at high temperature was better than those at low temperature, which enabled the recycled PC/ABS seperated from In-Panel to be applied to the radiator grille without the addition of the compatibilizers or virgin PC/ABS. This was ascribed to the smaller particle sizes of the PU foam formed at high extrusion temperature under high shear.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.9
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• pp.5737-5742
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• 2015

Insert injection molding is a process in which molten plastic is injected into a mold that contains a pre-placed insert. During the injection stage, the insert can be deformed by the pressure applied by the polymer melts. The deformation of the insert changes the width of the flow path around the insert, which can cause several defects such as short shots or warpages of the parts. In order to reduce the deformation of the insert, it is important to achieve successful design of gating system, insert geometry, and molding conditions. In the present study, the insert deformations that occured during the injection molding of the BLDC motor stator were investigated by numerical analyses. The gate location and the insert shape were modified to reduce the insert deformation. Finally, the injection molding with the modified designs was carried out, and it was confirmed that the insert deformation was reduced.

• Economic and Environmental Geology
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• v.17 no.3
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• pp.179-195
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• 1984

The Jurassic Daejeon and Nonsan granitoids are "S-type" syntectonic calc-alkaline two-mica monzogranite and granodiorite, respectively. With evidences of high CaO, $Al_2O_3$, LIL/HFS elements, total REE, (Ce/Yb)N and initial ($^{87}Sr/^{88}Sr$) ratio, and no significant Eu anomaly, the primary magmas for the Daejeon and Nonsan granitic rocks are derived from partial melting of the Precambrian granulite (e.g. grey gneisses). But those Jurassic granitoids crystallised from different chemical characteristics of parental magmas which is mainly due to varying degree of partial melting of the granulite (crustal anatexis). The absence of significant anomalous Eu($Eu/Eu^*=O.82{\sim}1.00$) in the Daejeon and Nonsan granitoids could indicate that feldspars, mainly plagioclase, did not separate from the magmas. The parental hydrous magmas could not rise appreciably above their source region before crystallisation. The Jurassic granitoids may be resulted by closing-collision situation and belong to the Hercynotype (Pitcher 1979) such as compressive ductile regime of an intracontinental orogen.

• Economic and Environmental Geology
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• v.20 no.1
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• pp.35-60
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• 1987

The geochemical characteristics including minerals, major and trace elements chemistries of the Proterozoic, Jurassic and Cretaceous granites in Korea are systematically summarized and intended to decipher the origin and crystallization process in connection with the tectonic evolution. The granites in Korea are classified into three different ages of the granites with their own distinctive geochemical patterns: 1) Proterozoic granitoids; 2) Jurassic granites(cratonic and mobile belt); 3) Cretaceous-Tertiary granites. The Proterozoic granite gneisses (I-type and ilmenite-series) formed by metamorphism of the geochemically evolved granite protolith. The Proterozoic granites (S-type and ilmenite-series) produced by remobilization of sialic crust. The Jurassic granites (S-type and ilmenite-series) were mainly formed by partial melting of crustal materials, possibly metasedimentary rocks. The Cretaceous granites (I-type and magnetite-series) formed by fractional crystallization of parental magmas from the igneous protolith in the lower crust or upper mantle. The low temperature ($315{\sim}430^{\circ}C$) and small temperature variations (${\pm}20{\sim}30^{\circ}C$) in the cessation of exsolution of perthites for the Proterozoic and Jurassic granites might have been caused by slow cooling of the granites under regional metamorphic regime. The high ($520^{\circ}C$) and large temperature variations (${\pm}110^{\circ}C$) of perthites for the Cretaceous granites postulate that the rapid cooling of the granitic magma. In terms of the oxygen fugacity during the feldspar crystallization in the granite magmas, the Jurassic mobile belt granites were crystallized in the lowest oxygen fugacity condition among the Korean granites, whereas the Cretaceous granites in the Gyeongsang basin at the high oxygen fugacity condition. The Jurassic mobile belt granites are located at the Ogcheon Fold Belt, resulting by closing-collision situation such as compressional tectonic setting, and emplaced into a Kata-Mesozonal ductile crust. The Jurassic cratonic granites might be more evolved either during intrusion through thick crust or owing to lower degree of partial melting in comparison with the mobile belt granites. The Cretaceous granites are possibly comparable with a continental margin of Andinotype. Subduction of the Kula-Pacific ridge provided sufficient heat and water to trigger remelting at various subcrustal and lower crustal igneous protoliths.

• The Journal of Engineering Geology
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• v.27 no.4
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• pp.489-500
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• 2017

It is not rare that pseudotachylite, dark colored rock with glassy texture, is recognizable in deep core samples drilled up to 900 m from the surface. Pseudotachylite with widths varying few to 20 cm is sharply contacted or interlayered with the host rocks composed of Jurassic granite and Precambrian amphibolite gneiss, showing moderately ductile deformation or slight folding. Pseudotachylite occurring at varying depths in the deep drill core are slightly different in texture and thickness. There is evidence of fault gouge at shallower depths, although brittle deformation is pervasive in most drill cores and pseudotachylite is identified at random depth intervals. Under scanning electron microscope (SEM), it is evident that the surface of pseudotachylite is characterized by a smooth, glassy matrix even at micrometer scale and there is little residual fragments in the glass matrix except microcrystals of quartz with embayed shape. Such textural evidence strongly supports the idea that the pseudotachylite was generated through the friction melting related to strong seismic events. Based on X-ray diffraction (XRD) quantitative analysis, it consists of primary minerals such as quartz, feldspars, biotite, amphibole and secondary minerals including clay minerals, calcite and glassy materials. Such mineralogical features of fractured materials including pseudotachylite indicate that the fractured zone might form at low temperatures possibly below $300^{\circ}C$, which implies that the seismic activity related to the formation of pseudotachylite took place at shallow depths, possibly at most 10 km. Identification and characterization of pseudotachylite provide insight into a better understanding of the paleoseismic activity of deep grounds and fundamental information on the stability of candidate disposal sites for high-level radioactive waste.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.12
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• pp.25-31
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• 2018

Selective Laser Melting is one of the representative 3D printing techniques for handling metal materials. The main factors influencing the characteristics of structures fabricated by the SLM method include the build-up angle of structures, laser power, laser scan speed, and scan spacing. In this study, the tensile properties of AlSi10Mg alloys were investigated by considering the build-up angle of tensile test specimens, laser scanning speed and scan spacing as variables. The yield stress, tensile strength, and elongation were considered as tensile properties. From the test results, it was confirmed that the yield stress values were lowered in the order of 0, 45, and 90 based on the manufacturing direction of the tensile specimen. The maximum yield stress value was obtained at 1870 mm / min based on the laser scan speed. The yield stress size decreased with decreasing scan speed. Based on the laser scan spacing, as the value increases, the yield stress increases, but the variation is smaller than the other test criteria. The tendency of the tensile strength and elongation variation depending on the test conditions was difficult to understand.

• Journal of the Korean Wood Science and Technology
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• v.27 no.3
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• pp.51-62
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• 1999

The objective of this research is to develop paper sludge reinforced thermoplastic composites which incorporate the advantages of each component materials. The effects of paper sludge content(0, 10, 20, 30, 40----), mesh size(20~40, 60~80, less than 100mesh), and coupling agent(Epolene E-43 and Epolene G-3003) on the mechanical properties of paper sludge-polypropylene composites were investigated. Composite density increased with an increase in the paper sludge content. When paper sludge is incorporated into a polypropylene matrix, the flexural properties of the composite increase significantly with an increase in the paper sludge mixing ratio. Especially, flexural modulus was improved with increasing paper sludge content. The flexural strength of composites was improved, but flexural modulus reduced somewhat with decreasing paper sludge particle size. The flexural properties of paper sludge-polypropylene composites were improved by using coupling agents to enhance the bonding between reinforcing filler and matrix. Use of the epolene E-43 and G-3003 resulted in considerable improvement in the flexural strength over control specimens. The flexural strength of the G-3003 composite system is higher than that of the E-43 system. Generally, izod notched impact strength of paper sludge-polypropylene composite decreased slightly, whereas izod unnotched impact strength decreased significantly with increasing paper sludge contents. There was no effects of paper sludge particle size on impact strength of paper sludge-polypropylene composites. And izod unnotched impact strength of epolene E-43 composite system sharply decreased but that of G-3003 composite system was no tendency with increasing additive content.