• Economic and Environmental Geology
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• v.17 no.2
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• pp.109-114
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• 1984

The geophysical implications of the observed heat flow in the Korean Peninsula are examined. The Peninsula can be devided into two typical regions of high (Zone 1) and normal heat flows (Zone 2), and anomalous sharp change of heat flow between two zones is noteworthy. Zone 1 (southeastern coast of the Peninsula) to be connected to the East Sea (=Japan Sea) of high heat flow region corresponds with the region of late-Mesozoic to Tertiary igneous activity. With the radioactive elements concentrated in the crust, the observed heat flow in Zone 2 can be almostly explained. While, only a half of the heat flow in Zone 1 is explained. As a possible explanation of high heat flow in Zone 1, partial melting in the lower crust is examined. The temperature of $800-900^{\circ}C$ calculated at the bottom of the crust excludes the possibility of partial melting or magma generation in the crust. Alternatively, a remaining thermal effect of late-Mesozoic to Tertiary igneous activity is considered. However, it appears that the thermal effect already disappeared and that the vertical temperature distribution reached at steady state 30 MY ago (= 10 MY after the igneous activities came to an end). After all, the existence of some other effective heat transfer in Zone 1 is strongly suggested. The high heat flow to be same kind of anomalous one of the East Sea can be recognized as a result of the trench-back-arc thermal flux. The plate subduction in the Japan Trench will generate an induced flow above the slab of the East Sea, a typical back-arc basin, and hence the induced flow will heat the surrounding lithosphere.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.6
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• pp.26-33
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• 2008

This paper presents a new full-bridge soft switching PWM DC-DC converter circuit topology that adding one switcher, one lossless snubber quasi-resonance capacity to power source for general welding machine This full-bridge soft switching DC-DC convoter· topology can applicable 600[V] switching device (IGBT)incase of AC 400[V] common power source because the voltage of active switcher is 1/2 of DC bus line voltage. And low voltage hight current out)ut that first coil current is smaller than second coil current in high frequency transformer can be obtained with decreasing path loss in conventional DC bus line switcher. As it operate ZCS/ZVS in full range, high frequency, high efficiency and high output are implemented at low voltage and high DC current switching power supplies. All of this items are got from simulation and the result of experiment. If make up for the weak points of this proposed circuit, it will be used more easily for next generation TIG, MIG and MAG type of arc-welding machine.

• Economic and Environmental Geology
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• v.45 no.2
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• pp.145-156
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• 2012

Seafloor hydrothermal system occurs along the volcanic mid-ocean ridge, back-arc spreading center, and other submarine volcanic regions. The hydrothermal system is one of the fundamental processes controlling the transfer of energy and matter between crust/mantle and ocean; it forms hydrothermal vents where various deepsea biological communities are inhabited and precipitates metal sulfide deposits. Hydrothermal systems at convergence plate boundaries show diverse geochemical properties due to recycle of subducted material compared to simple systems at mid-ocean ridges. Sulfur isotopes can be used to evaluate such diversity in generation and evolution of hydrothermal system. In this paper, we review the sulfur isotope composition and geochemistry of hydrothermal precipitates sampled from several hydrothermal vents in the divergent plate boundaries in the western Pacific region. Both sulfide and sulfate minerals of the hydrothermal vents in the arc and backarc tectonic settings commonly show low sulfur isotope compositions, which can be attributed to input of magmatic $SO_2$ gas. Diversity in geochemistry of hydrothermal system suggests an active role of magma in the formation of seafloor hydrothermal system.

• Journal of the Korean Geographical Society
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• v.43 no.2
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• pp.235-252
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• 2008

Many cartographers have for many years searched for a way to construct cartograms in which the sizes of geographic areas such as states, counties or census tracts are reseated in proportion to their population or some other socio-economic properties. While many techniques and algorithms for creating cartograms have been proposed, some of them are still extremely complex to generate in a proper manner, and many of them suffer either from this lack of readability or from seamless integration with GIS software. This paper, therefore, presents a simple population cartogam technique based on the Circular Cartogram Algorithm(CCA) by Dorling(1996) to tackle these drawbacks by drawing the areas as simple circles for use as a base map and linking the construction with GIS mapping processes. For an automated approach in the cartogram generation, this paper proposes a close coupling method of ArcView GIS 3.3. package in order for users to access to the cartopam algorithm. Then, they will be available through an interface that the ArcView GIS system allows user-written routines to be accessed easily. The CCA and its coupling architecture ensure to improve the potential applicability of the use of cartograms to census mapping at practical levels. As the cartogram examples, cartograms of population and property types in 2005 Korea census data sets are illustrated in the end, by which viewers can easily identify the residential concentration and their relative ratio in Seoul metropolitan area.

• Journal of the Korean Vacuum Society
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• v.18 no.3
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• pp.236-243
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• 2009

Proton Engineering Frontier Project (PEFP) has supplied the metal ions to users by using an installed metal ion implanter of 120 keV. At present a feasibility study is being performed for a cobalt ion implantation. For a cobalt ion extraction we studied to sustain the high temperature($648^{\circ}C$) for metal ions vaporization from a cobalt chloride powder by using an alumina crucible in the ion source. The temperature condition of the crucible was satisfied with the plasma generation at the arc current of 120V and EHC power of 250W. The extracted beam current of $Co^+$ ions was dependent on the arc current in the plasma. The maximum beam current was $100{\mu}A$ at 0.18A of the arc current. The 3 peak currents of the extracted ions such as $Co^+$, $CoCl^+$ and $Cl^+$ were obtained by adjusting a mass analyzing magnet and the $Co^+$ ion beam peak current fraction as around 70% in the sum of the peak currents. The fluence of the implanted cobalt ions at the $10{\mu}A$ of the beam current and 90 minutes of the implantation time into an aluminum sample as measured around $1.74{\times}10^{17}#/cm^2$ by a quantitative analysis method of RBS (Rutherford Backscattering Spectrometry).

• Journal of the Korea Institute of Building Construction
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• v.18 no.5
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• pp.419-427
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• 2018

The purpose of this study is to recycle steel slag generated from the iron producing process and to use steel slag as a construction material which is currently landfilled Steel slag is subjected to aging treatment due to the problem of expansion and collapse when it reacts with water. The Slag Atomizing Technology (SAT) method developed to solve these problems of expanding collapse of steel slag. In this study, experimental study on the emergency repair mortar using the reducing slag, electric arc furnace slag and silicon manganese slag manufactured by the SAT method is Reduced slag was shown an accelerated hydration when it was replaced with rapidly-setting cement, and the rate of substitution was equivalent to 15%. It is shown that the electric furnace oxide slag is equivalent to 100% of the natural aggregate, and it can be replaced by 15-30% when the silicon manganic slag is substituted for the electric furnace oxide slag. With the above formulation, it was possible to design the rapidly repair mortar for road use. These recycling slags can contribute on achieving sustainability of construction industry by reducing the use of cement and natural aggregates and by reducing the generation of carbon dioxide and recycling waste slag.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.51 no.5
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• pp.242-248
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• 2002

It is important to develop new effective technologies to increase the interruption capacity and to reduce the size of a UB(Gas Circuit Breakers). Major design parameters such as nozzle geometries and interrupting chamber dimensions affect the cooling of the arc and the breaking performance. But it is not easy to test real GCB model in practice as in theory. Therefore, a simulation tool based on a computational fluid dynamics(CFD) algorithm has been developed to facilitate an optimization of the interrupter. Special attention has been paid to the supersonic flow phenomena between contacts and the observation of hat-gas flow for estimating the breaking performance. However, there are many difficult problems in calculating the flow characteristics in a GCB such as shock wave and complex geometries, which may be either static or in relative motion. Although a number of mesh generation techniques are now available, the generation of meshes around complicated, multi-component geometries like a GCB is still a tedious and difficult task for the computational fluid dynamics. This paper presents the CFD program using CFB-CAD integration technique based on Cartesian cut-cell method, which could reduce researcher's efforts to generate the mesh and achieve the accurate representation of the geometry designed by a CAD tools.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.2
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• pp.349-353
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• 2012

As the world wind energy market grows rapidly, the productions of wind power generation equipment have recently increased, but manufacturers are not able meet this requirement. Particularly offshore wind energy industry is one of the most popular renewable energy sectors. To generalize welding processes, the welding automation is considered for steel structure manufacturing in offshore wind energy to get high quality and productivity. Welding technology in construction of the wind towers is depended on progress productivity. In addition, the life of wind tower structures should be considered by taking account of the natural weathering and the load it endures. The root passes are typically deposited using Gas Tungsten Arc Welding(GTAW) with a specialized backing gas shield. Not only the validation consists of welders experienced in determining the welding productivity of the baseline welding procedure, but also the standard testing required by the ASME section IX and API1104 codes, toughness testing was performed on the completed field welds. This paper presents the welding characteristics of the root-pass welding of high tensile steel in manufacturing of offshore wind tower. Based on the result from welding experiments, optimal welding conditions were selected after analyzing correlation between welding parameters(peak current, background current and wire feed rate) and back-bead geometry such as back-bead width(mm) and back-bead height performing root-pass welding experiment under various conditions. Furthermore, a response surface approach has been applied to provide an algorithm to predict an optimal welding quality.

• Resources Recycling
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• v.12 no.6
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• pp.47-56
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• 2003

PVC(polyvinyl chloride) powder were mixed with EAF(Electric Arc Furnace) dust and made as pellets. In order to recover the hydrochloride emitted from pyrolysis of PVC and the valuable metals in dust through making chlorides, pellets were roasted at $300 ^{\circ}C$ and investigated about the generation of chlorides. Two dust samples were collected at I steel making Co. and P Co. (called I dust and P dust respectively), which were mainly composed of zincite and franklinite. It was confirmed that about 50% of Zn in I dust and 48% of Zn in P dust compose zincite. The emission of HCl gas was completed in 15 min at 30$0^{\circ}C$ and the HCl mostly reacted with dust and made chlorides under 20% PVC mixed ratio. Because the reaction of HCl with zincite was faster than with franklinit, when generation and volatilization of ferric chloride is not allowed, the equivalent PVC powder mixed ratio in pellet depended on the amount of zincite in dust.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.5
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• pp.1003-1012
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• 2022

The horizontal force transfer to the turbine and substructure of a wind power generation system is a very important factor in maintaining the safety of the system, but it is inevitably vulnerable to large-scale coastal disasters such as earthquakes and typhoons. Wind power generation systems built on the coast or far offshore are very disadvantageous in terms of economic feasibility due to an increase in initial investment cost because a more robust design is required when installed in areas vulnerable to coastal disasters. In this study, the GIS method was used to select the optimal site for a wind farm from the viewpoint of reducing the risk of coastal disasters. The current status of earthquakes in the West and South Seas of Korea, and the path and intensity of typhoons affecting or passing through the West and South Seas were also analyzed. Accordingly, the optimal offshore wind farm site with the lowest risk of coastal disasters has been selected and will be used as basic research data for offshore wind power projects in the region in the future.