• 한국지구물리탐사학회:학술대회논문집
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• 2007.06a
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• pp.267-272
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• 2007

Uiseong subbasin belonging to Kyungsang basin resulted from volcanic activity in the late Cretaceous. In this study, we carry out MT and gravity survey at the Hwasan caldera, which was formed of volcanic and abyssal rocks complex, then analyze and identify geological substructure. Potential survey such as gravity and magnetic survey has been mainly carried out in former studies, so depth information for understanding substructure was not enough. To complement a potential survey, we use MT method, which has high vertical resolution. Moreover we make a simple 2D model comparing with former study. The result of MT and gravity 2D modeling shows that this area is roughly composed of 3 layers; The bottom layer is a basement. In the second layer, intrusive rocks having high resistivity is placed along the ring faults and the sedimentary layer of low resistivity is inside caldera. The highest layer is alluvium. To comprehend the 3D structure of the Hwasan caldera, we perform 3D gravity inversion, and construct the 3D model from the result of 3D gravity inversion. MT responses are calculated by using the constructed 3D model and the 3D model of the Hwasan caldera's structure is suggested after comparing the calculated values with the observed values at MT line.

• Composites Research
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• v.31 no.1
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• pp.8-11
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• 2018

Sheet molding compound (SMC) is one of the most economical fiber reinforced composite fabrication processing for automotive applications. In this study, we studied the optimum formulation for the production of SMC which shows low specific gravity without lowering the mechanical properties by using glass bubble (GB) which is a low specific gravity filler and glass fiber (GF) as a reinforcing material. The tensile strength increased with the increase of the GF in the SMC, and the specific gravity decreased with the increase of the GB. The synergistic effect of improving the mechanical properties as the specific gravity is lowered is found in the optimum formulation. The synergy effect was confirmed by the internal structure analysis that the dispersion effect of the crack propagation of the GB and the improvement of the binding force between the fiber and the matrix due to the incorporation of the GB.

• Korean Journal of Food Science and Technology
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• v.6 no.1
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• pp.12-16
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• 1974

The amino acid pattern of embryo and endosperm of brown rice different in specific gravity was investigated using Jinheung (local leading temperate variety) and IR667-Suweon 213 (high-yielding newly bred tropical variety). 1. Embryo of IR667 (higher protein rice) showed lower protein, and lower lysine or essential amino acid per protein than that of Jinheung (lower protein rice). 2. In both embryo and endosperm nitrogen recovery as amino acids was highest in middle class of specific gravity and lowest in low class indicating that abundancy of non-protein nitrogen in low class and decomposition of amino acids by starch in high specific gravity class. 3. In both embryo and endosperm IR667 showed abundancy in order of glutamic acid, aspartic acid while Jinheung showed glutamic acid, arginine, suggesting varietal difference in nitrogen metabolism. 4. In both IR667 and Jinheung least amino acid was histidine and next leucine in embryo but histidine and next threonine in endosperm, suggesting organ difference in nitrogen metabolism.

• Magazine of the Korean Society of Agricultural Engineers
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• v.38 no.4
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• pp.125-136
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• 1996

In order to investigate the characteristics of gravity drainage for geotextile, small-scale model tests for the geotextile chimney drain of earth dam which is a typical type of gravity drainage were carried out using 15 kinds of nonwoven and composite geotextiles. According to the results of this study, the drainage discharge of geotexgile drain generally increases with exponential function as hydraulic head increases and the increasing rate is greater in the coarser soil of dam material. It has a trend to increase when the construction slope of geotextile drain is steeper and the number of layers of geotextile is more. The relationship between the transmissivity of geotextile and the drainage discharge has positive correlation and the rate of increase is greater in the coarser soil. The geotextile products must be carefully selected in consideration of transmissivity of geotextile when the soil to be drained is coarser and the seepage flow is relatively high. Most of staple fiber nonwoven geotextile used in this study are found to be appropriate for drainage purpose. Among them, the composite geotextile the type of which geotextile is evaluated to be the most excellent material. But the geotextile of low permeability such as filament thermal bonded and filament spunbonded nowovens closely examined their transmissivity especially to be used for drainage function.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.2
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• pp.55.5-56
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• 2017

Galaxy dynamics probes weak gravity at accelerations below the de Sitter scale of acceleration adS = cH, where c is the velocity of light and H is the Hubble parameter. Low and high redshift galaxies hereby offer a novel probe of weak gravity in an evolving cosmology, satisfying H(z) = H0(1 + A(6z + 12z^2 +12z^3+ 6z^4+ (6/5)z^5)/(1 + z) with baryonic matter content A sans tension to H0 in surveys of the Local Universe. Galaxy rotation curves show anomalous galaxy dynamics in weak gravity aN < adS across a transition radius r beyond about 5 kpc for galaxy mass of 1e11 solar mass. where aN is the Newtonian acceleration based on baryonic matter content. We identify this behavior with a holographic origin of inertia from entanglement entropy, that introduces a C0 onset across aN=adS with asymptotic behavior described by a Milgrom parameter satisfying a0=omega/(2pi), where omega=sqrt(1-q)H is a fundamental eigenfrequency of the cosmological horizon. Extending an earlier confrontation with data covering 0.003 < aN/adS < 1 at redshift z about zero in Lellie et al. (2016), the modest anomalous behavior in the Genzel et al. sample at redshifts 0.854 < z <2.282 is found to be mostly due to clustering 0.36 < aN/adS < 1 close to the C0 onset to weak gravity and an increase of up to 65% in a0.

• Proceedings of the KSRS Conference
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• 2007.10a
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• pp.65-68
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• 2007

FORMOSAT-3 was launched in April of 2006. It consists of six low earth orbit (LEO) satellites that will be eventually deployed to an orbit at 800 km height. Its scientific goal is to utilize the radio occultation (RO) signals to measure the bending angles when the GPS signals transect the atmosphere. The bending angle is then used to infer atmospheric parameters, including refractivity, temperature, pressure, and relative humidity fields of global distributions through inversion schemes and auxiliary information. The expected number of RO events is around 2500 per day, of which 200 events or so fall into the polar region. Consequently, the FORMOSAT-3 observations are expected to play a key role to improve our knowledge in the weather forecasting and space physics research in the polar region. In this paper, we use temperature profiles retrieved from FORMOSAT-3 RO observations to study the climatology of gravity wave activity in the polar region. FORMOSAT-3 can provide about 200 RO observations a day in the polar region, much more than previous GPS RO missions, and, hence, more detailed climatology of gravity wave activity can be obtained.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.774-778
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• 2004

The atomization process of a circular $SF_{6}$ liquid jet issued into an otherwise quiescent, high-pressure $N_2$ gas was observed to explore the breakup mechanism of liquid ligaments involved in turbulent atomization. Both liquid and gas temperatures were fixed at a room temperature but the gas pressure was elevated to more than twice the critical pressure of $SF_{6}$. Therefore, the liquid surface was in a thermodynamic state close to a critical mixing condition with suppressed vaporization. Since the surface tension and the surface gas density approach zero and the surface liquid density, respectively, phenomena equivalent to those which would appear when a very high speed laminar flow of water were injected into the atmospheric-pressure air can be observed by issuing $SF_{6}$ liquid at low speeds in micro-gravity environment which avoid disturbances due to gravity forces. The instability ob near-critical mixing surface jet was quantitatively characterized using a newly developed device, which could issue a very small amount of $SF_{6}$ liquid at small constant velocity into a very high-pressure $N_2$ gas.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.454-459
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• 2004

This paper considers the problem of satellite's orbit control and a solution based in Linear Matrix Inequalities (LMI) is proposed for the case of Low Earth Orbiters (LEO). In particular, the modelling procedure and the algorithm for control law synthesis are tested using as study case the European Gravity Field and Ocean Circulation Explorer satellite (GOCE), to be launched by the European Space Agency (ESA) in the year 2006. The scientific objective of this space mission is the recovering of the Earth gravity field with high accuracy (less than 10${\mu}m$/${\mu}m$) and spatial resolution (better than 100km). In order to meet these scientific requirements, the orbit control must guarantee stringent specifications in terms of environmental disturbances attenuation (atmospheric drag forces) even in presence of high levels of model uncertainty.

• Animal cells and systems
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• v.4 no.3
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• pp.195-200
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• 2000

In this article I discuss the main results of our research in space biology from the simple early investigations with human Iymphocytes in the early eighties until the projects in tissue engineering of the next decade on the international space station ISS. The discovery that T Iymphocyte activation is nearly totally depressed in vitro in 0g conditions showed that mammalian single cells are sensitive to the gravitational environment. Such finding had important implications in basic research, medicine and biotechnology. Low gravity can be used as a tool to investigate complicated and still obscure biological process from a new perspective not available to earth-bound laboratories. Low gravity may also favor certain bioprocesses involving the growth of tissues and thus lead to commercial and medical applications. However, shortage of crew time and of other resources, lack of sophisticated instrumentation, safety constraints pose serious limits to biological endeavors in space laboratories.

• Journal of the Korean Wood Science and Technology
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• v.30 no.3
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• pp.104-108
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• 2002

Nail withdrawal tests were conducted on clear wood of domestic small diameter logs. Nails were driven into the cross and longitudinal sections of each specimen, then nail withdrawal tests were performed. Nail withdrawal loads are strongly dependent on the direction of nail positions. The average load values for the nail withdrawal both in cross section and longitudinal section are higher in high specific gravity (SG) wood of sawtooth oak (Quercus acutissima Carr.) than those in low SG wood of Korean red pine (Pinus densiflora Sieb. et Zucc.) and pitch pine (Pinus rigida Mill.). The average ratio of the nail withdrawal loads for side-grain and end-grain are higher in the low SG wood than that in the high SG of wood. Both linear and non-linear regression analyses were conducted on nail withdrawal load with SG, good correlations were obtained between nail withdrawal load and SG.