• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.29 no.1
• /
• pp.81-89
• /
• 2011

The previous land gravity data in Korea showed locally biased irregular distribution. Especially, this problem was more serious in the mountainous area where the data density was significantly low. The same problem appeared in GPS/Levelling data thus the precision of the geoid could not be improved. From 2008, new gravity and GPS/Levelling data has been collected by the unified control point and survey on the benchmark project which were funded by the national geographic information institute. The newly obtained data has much better distribution and precision so that it could be used for update precision of geoid model. In this study, the new precision geoid has been calculated based old and new gravity data and this model showed 5.29cm of precision compared to 927 points of GPS/Levelling data. And the degree of fit and precision of hybrid geoid has been calculated 2.99cm and 3.67cm. The new gravimetric geoid has been updated about 27% over whole country. And it showed 42% of precision update due to collection of new gravity data on the Kangwon/Kyeongsang area which showed quite low distribution. In 2010, about 4,000 points of gravity and 300 points of GPS/Levelling data has been obtained by unified control and survey on benchmark project. We expect that new data will contribute to updating geoid precision and veri tying precision more objectively.

• Horticultural Science & Technology
• /
• v.28 no.4
• /
• pp.545-551
• /
• 2010

The primary objective of this study was to determine the relationship between fruit quality characteristics and pithiness fruit occurrence for confirming occurrence factors of pithiness tissues in 'Niitaka' pears ($Pyrus$ $pyrifolia$ Nakai). Fruits were harvested 4 times in 1 week intervals from 160 days after full bloom (DAFB) to 181 DAFB. Harvested fruits were separated with the specific gravity by Archimedes laws. Also, with specific gravity level in pear fruit, sugar content, acidity, and texture profile analysis (TPA) were investigated. Final verifiability of pithiness fruit was approved by eye observation at 90 days after storage. Also, in ASS (Alcohol Soluble Solid) and AIS (Alcohol Insoluble Solid), calcium contents were investigated. Although the differences in sugar and organic acid content were not significant in fruits divided by gravity, flesh hardness was depressed in fruits that showed low gravity. These results were more conspicuous in late harvested fruits (at 174 and 181days after full bloom) which showed low gravity, representing less content of AIS content and calcium in ASS and AIS when compared with early harvest fruits. Fruits of lower gravity below 1.0 measured with dipping induced the progression of pithiness symptom up to 76%. Consequently, harvest timing is a more concise factor in pithiness fruit occurrence although those symptom also affected by storage condition. Furthermore, the cause of pithiness fruit occurrence by late harvest is due to the lower cell wall binding calcium.

• Economic and Environmental Geology
• /
• v.38 no.3 s.172
• /
• pp.285-297
• /
• 2005

Seismic reflection profile analysis, potential field analysis, and potential field modeling using deep seismic reflection, gravity, magnetic, and geological data were performed to better understand the location and nature of the Grenville Front in Ohio, USA. The seismic reflection profile reveals a broad zone of east dipping basement reflectors associated with the Grenville Front in western Ohio and a broad region of west dipping reflectors cutting through the entire crust in eastern Ohio. Potential field analysis indicates that the Grenville Front is characterized by a gravity low, an associated gravity positive and a magnetic high. The results of the gravity and magnetic modeling using seismic data suggest that the lower crust is thickened at the interpreted position of the Grenville Front and high grade metamorphic rocks make up the Grenville Front Tectonic Zone (GFTZ). The gravity low at the Grenville Front is due to the thickened crust, while the magnetic high is due to high grade metamorphic rocks. The gravity high immediately east of the GFTZ in central Ohio is caused by thrusting of high density lower and middle crustal rocks into the upper crust. There is no compelling evidence that this gravity high is related to a Precambrian rift zone as has been suggested in previous studies.

• Journal of the Geological Society of Korea
• /
• v.54 no.6
• /
• pp.641-656
• /
• 2018

Although an amount of hydrocarbon has been discovered in the West Korea Bay Basin (WKBB), located in the North Korean offshore area, geophysical investigations associated with these hydrocarbon reservoirs are not permitted because of the current geopolitical situation. Interpretation of satellite derived potential field data can be alternatively used to image three-dimensional (3D) density distribution in the sedimentary basin associated with hydrocarbon deposits. We interpreted the TRIDENT satellite-derived gravity field data to provide detailed insights into the spatial distribution of sedimentary density structures in the WKBB. We used 3D forward density modeling for the interpretation that incorporated constraints from existing geological and geophysical information. The gravity data interpretation and 3D forward modeling showed that there are two modeled areas in the central subbasin that are characterized by very low density structures, with a maximum density of about $2,000kg/m^3$, indicating some type of hydrocarbon reservoir. One of the anticipated hydrocarbon reservoirs is located in the southern part of the central subbasin with a volume of about $250km^3$ at a depth of about 3,000 m in the Cretaceous/Jurassic layer. The other hydrocarbon reservoir should exist in the northern part of the central subbasin, with an average volume of about $300km^3$ at a depth of about 2,500 m. A comparison between the TRIDENT derived gravity field and the ship-based gravity field measured in 1980s shows us that our results are highly reliable and there is a very high probability to detect another low-density layer existings in the northwestern part of the central subbasin.

• Journal of Fashion Business
• /
• v.11 no.5
• /
• pp.155-164
• /
• 2007

Viscose rayon has advantages such as vivid luster, good dyeability, low static electricity, good absorbance and good spinnability but also has flaws such as easy crease and decrease of physical properties when it gets wetting, and it requires dry cleaning. Therefore in order to synthesize the polymer to solve the problems of rayon while keeping the advantages of it, this study made the high specific gravity polyester for ultra drape property and high contraction polyester for rayon-like fiber having volume, soft and warm sense. The polyester with high specific gravity, 1.47 was made by adding 7 wt% of $BaSO_4$ as additive. High contraction polyester was made by copolymerization by using IPA 5 mole% to increase the amorphous region as comonomer and also using Newpol BPE-20(NPE) 1.5 wt% not to decrease the properties.

• Proceedings of the KSRS Conference
• /
• 2008.10a
• /
• pp.192-195
• /
• 2008

Radio occultation (RO) has been used in the planetary science since Microlab-1 was launched in 1995. With the RO technique, the profiles of atmosphere and the global atmospheric data can be obtained. In 2006, Taiwan launched six low Earth orbit (LEO) satellites as the RO constellation mission, known as FORMOSAT-3. In order to retrieve the RO data from original data, a retrieval algorithm, NCURO, is developed. The input of NCURO algorithm is mainly the excess phase of GPS signal, and the output is the dry pressure and dry temperature. Using temperature profiles retrieved by NCURO algorithm, temperature perturbation and potential energy of gravity wave have been evaluated. In this paper, the retrieval algorithm and the global distribution of energy of gravity waves are described and demonstrated.

• International Journal of Railway
• /
• v.3 no.1
• /
• pp.1-6
• /
• 2010

The steel plate-girder bridges with concrete gravity piers have possibilities of overturning by lateral inertial force which can be reproduced by sudden earthquake attack. This paper explores an overturning mechanism of existing concrete gravity pier onto the sandy soil in the event of lateral push-over load by in-situ experimental observation. The in-situ push-over experiment for pier with earth anchors between spread footing and rock beds exhibits a reasonable enhancement of ductility against overturning. In unanchored system, a flexural crack at cold joint of concrete pier is not developed because of the over-turning of the pier. This leads a global instability (rotation) of pier-footing system with relatively low stresses in pier itself. While a lateral load is persistently increased in anchored system, the successive flexural cracking failure at cold joint is observed even after the local shear failure of soil due to redistribution of stress equilibrium between soil and pier structure as long as a tensile action of anchor cable is active.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.26 no.5
• /
• pp.519-527
• /
• 2008

The basic elements in precise geoid determination are the gravity and topographic data with reliable quality and distribution. In this study, the effect of the gravity and topographic data on the precision of the geoid are analyzed through simulations in which the quality and distribution of the data are artificially controlled. It was found that the distribution of the topographic data has more effect on the precision of geoid than the quality of the it. This leads to the conclusion that the SRTM (Shuttle Radar Topography Mission) DTM (Digital Terrain Model) with resolution of 90m is qualified as a topographic data in geoid determination. In the experiments with gravity data, on the other hand, the aliasing effect caused by the low data density caused large errors in geoid. It was found that the more gravity data especially in north-eastern mountainous area is needed for precise geoid determination in Korea.

• 한국지구물리탐사학회:학술대회논문집
• /
• 2005.05a
• /
• pp.9-14
• /
• 2005

For the understanding the locus of the Quinling-Dabie-Sulu continental collision's boundary and the underground structure of the sedimentray basin in the Yellow Sea, three dimensional density modelling is carrid out by using gravity dataset (Free Air Anomaly), which is measured by Tamhae 2, KIGAM in a period 2000 - 2002. The measured gravity anomaly in the investigations area is mainly responsed by depth distribution of the sedimentary basin. After comparing the sea-measured gravity data to CHAMP-GRACE satellite gravity data, I suggested that the high density model bodies extend mainly from the southern part of China to the middle-western part of the Korean Peninsula., which might be emplaced along the continental collision's boundary. The total volume of very low density bodies modified by modelling might be about $20000\;km^3$.

• Economic and Environmental Geology
• /
• v.20 no.3
• /
• pp.203-209
• /
• 1987

The gravity measurement has been conducted at 69 points with an interval of about 1km along the national road between Masan and Busan through Kimhae to study on the subsurface geology and structure of Kyongsang basin. The Bouguer gravity anomalies were obtained from the observed gravity values, and interpreted by means of the Fourier-series method and Talwani method for 2-dimensional body. The depth of Conrad discontinuity is about 14.8km at the west end of survey line, and increases smoothly to about 13.6km at the east end. But it is uplifted by about 500m between Yangsan and Dongnae faults. The depth of the basement of Kyongsang basin is about 4.8km at the west end. It decreases gradually passing Masan, and reaches the maximum depth of 5.6km at the 15km east of Masan. Hereafter, it starts to increase to 4.3km at the east end. It is also uplifted by about 500m between Yangsan and Dongnae faults. The Bulgugsa granites which cause two low Bouguer gravity anomaly zones are distributed in the vicinity of Masan at depth of about 3.5km and Kimhae area at depth of about 5.3km. Diorite, granodiorite, aplite, and felsite are distributed with various depth of about 1~1.7km, and Jusasan andesitic rocks, except porphyritic one located at the west of Kimhae, are distributed with depth of about 1km. Three fracture zones associated with faults are located at the places where v-shaped Bouguer gravity anomalies are appeared.