• 한국지구물리탐사학회:학술대회논문집
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• 2006.06a
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• pp.209-210
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• 2006

The Bismarck Sea represent a unique region in the equatorial western Pacific where one can explore the relationship between tectonic and magmatic processes associated with back-arc opening. The sea, located north of Papua New Guinea and just south of the equator, formed during the final stages of a long, complex geological development of the Melanesian Borderland. The development resulted from the Cenozoic convergence between the Australian and Pacific- Caroline Plates and the opening of back-arc basins. At present, the Bismarck Sea straddles two oppositely facing trenches, the inactive Manus trench and the active New Britain trench, and covers two basins, the New Guinea Basin (NGB) to the west and the Manus Basin (MB) to the east. The two basins are separated by the shallow Willaumez-Manus Rise (WMR), which trends roughly from WNW to ESE. The origin of these major structural units and their relationship with the presentday zone of major seismicity along the Bismarck Sea Seismic Lineation (BSSL) remains unclear and is the main focus of our study.

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.3
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• pp.457-465
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• 1988

The inside contact characteristics in abrasive belt drives were investigated analytically and experimentally for (1) driver pulley contact wheel and (2) driven pulley contact wheel. The concentrated contact forces in the grinding zone divided the entire belt-pulley contact are by three distinct areas and the tangential friction forces in the active areas caused the normal forces to change, which resulted in the different belt force distribution compared with those of the ordinary flat belt drives. The experimental results for the normal pressure (belt tension) distribution were in good agreement with the theoretical results.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.6
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• pp.226-233
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• 1998

In this paper, an experimental study was performed to investigate the speed ratio-torque-thrust characteristics for metal belt CVT. It is observed from the experimental results that nondimensional secondary thrust force follows with the existing theoretical formula with ${\mu}$=0.09~0.12 depending on the torque and the speed ratio. In order to represent these characteristics, an effective friction coefficient was introduced. Also, the slip characteristics between the belt and the pulley were investigated experimentally and traction coefficients at gross slip were obtained for various speed ratios. Using the traction coefficients and the effective friction coefficients, an improved formula for the secondary thrust force was suggested assuming that thrust force is the summation of the thrust of pseudo inactive arc and the thrust of pseudo active arc. The effective friction coefficient and the improved formula for the speed ratio-torque-thrust relationship suggested in this work can be used to obtain the appropriate secondary thrust.

• Journal of Astronomy and Space Sciences
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• v.32 no.3
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• pp.237-245
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• 2015

A strategy is needed for a regional survey of geosynchronous orbits (GSOs) to monitor known space objects and detect uncataloged space objects. On the basis of the Inter-Agency Debris Committee's recommendation regarding the protected region of geosynchronous Earth orbit (GEO), target satellites with perigee and apogee of $GEO{\pm}200km$ and various inclinations are selected for analysis. The status of the GSO region was analyzed using the satellite distribution based on the orbital characteristics in publicly available two-line element data. Natural perturbation effects cause inactive satellites to drift to two stable longitudinal points. Active satellites usually maintain the designed positions as a result of regular or irregular maneuver operations against their natural drift. To analyze the detection rate of a single optical telescope, 152 out of 412 active satellites and 135 out of 288 inactive satellites in the GSO region were selected on the basis of their visibility at the observation site in Daejeon, Korea. By using various vertical view ranges and various numbers of observations of the GSO region, the detection efficiencies were analyzed for a single night, and the numbers of follow-up observations were determined. The orbital estimation accuracies were also checked using the arc length and number of observed data points to maintain the GSO satellite catalog.

• Journal of the Korean earth science society
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• v.18 no.6
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• pp.559-564
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• 1997

The New Hebrides Basin is an inactive non back-arc basin located at the convergent boundary of the Pacific and Info-Australian plates. This basin was formed from 46 Ma to 60 Ma. The basin has two spreading episodes with rates of 34 mm/a for 42 to 47 Ma and 17 mm/a for 47 to 60 Ma. The sediments covered in the basin has uniform thickness of 0.65 sec. The age-depth correlation curve of the New Hebrides Basin can be represented by the following equation: $Depth(m)=2689+312\sqrt{Age}(Ma)$ The coefficient of 312 in this equation is close to that for major oceans, 350. This suggests that the cooling processes of the lithospheres in the New Hebrides Basin and major oceans are similar to each other. Free-air gravity anomalies of the basin varying from -22.3 mgal to +59.0 mgal. The mean value is +30.2 mgal higher than those of the normal oceans. Moderately large free-air gravity anomalies in the New Hebrides Basin are presumably owing to its location on a marginal swell along the New Hebrides Trench. It is generally observed that the ocean floor is very gently uplifted in a zone about 200 km oceanward of the trench axis. Positive free-air gravity anomalies amounting to $50{\sim}60$ mgal are usually observed on the crest of the swell. This topography is presumably by bending of the oceanic lithosphere so as to dynamically maintain nonisostatic states for some duration.

• Journal of the Korean Electrochemical Society
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• v.18 no.2
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• pp.68-74
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• 2015

To compare the microstructure and electrochemical properties between two binary alloys (Cr-Si, Ni-Si), two composition of binary alloys with the same capacity were selected using phase-diagram and prepared by matrix-stabilization method to suppress the volume expansion of Si by inactive-matrix. Master alloys were made by Arc-melting followed by fine structured ribbon sample preparation by Rapid Solidification Process (RSP, Melt-spinning method) under the same conditions. Also powder samples were produced by wet grinding for X-Ray Diffraction (XRD) and electrochemical measurements. As predicted from the phase diagram, only active-Si and inactive-matrix ($CrSi_2$, $NiSi_2$) were detected. The results of Scanning Electron Microscope (SEM) and Transmission Electron Microscopy - Energy Dispersive X-ray Spectroscopy (TEM-EDS) show that Cr-Si alloy has finer microstructure than Ni-Si alloy, which was also predictable through phase diagram. The electrochemical properties related to microstructure were evaluated by coin type full- and half-cells. Separately, self-designed test-cells were used to measure the volume expansion of Si during reaction. Volume expansion of Cr-Si alloy electrode with finer microstructure was suppressed significantly and improved in cycle capability, in comparison Ni-Si alloy with coarse microstructure. From these, we could infer the correlation of microstructure, volume expansion and electrochemical degradation and these properties might be predicted by phase diagram.

• Economic and Environmental Geology
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• v.46 no.3
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• pp.207-214
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• 2013

To identify rock-magnetic properties of volcanogenic hydrothermal sulfide deposits, chimneys were obtained from the Tofua Arc in Southwest Pacific, using a remotely operated vehicle (ROV) and Grab with AV cameras (GTVs). Three different types of chimneys used in this study are a high-temperature chimney with venting fluid-temperature of about $200^{\circ}C$ (ROV01), a low-temperature chimney of about $80^{\circ}C$ (GTV01), and an inactive chimney (ROV02). Magnetic properties of ROV01 are dominated by pyrrhotite, except for the outermost that experienced severe oxidation. Concentration and grain-size of ROV01 pyrrhotite are relatively low and fine. For GTV01, both magnetic concentration and grain-size increase from interior to margin. Pyrrhotite, dominant in the core, becomes mixed with hematite in the rim of the chimney due to secondary oxidation. High concentration and large grain-size of magnetic minerals characterize the ROV02. Dominant magnetic phases are pyrrhotite, hematite and goethite. In particular, the outermost rim shows a presence of magnetite produced by magnetotactic bacterial activity. Such distinctive contrast in magnetic concentration, grain-size and mineralogy among three different types of chimney enables the rock-magnetic study to characterize an evolution of hydrothermal deposits.