• Journal of Fisheries and Marine Sciences Education
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• v.3 no.2
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• pp.19-28
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• 1991

The United States has been developing a GPS(Global Positoning System), and now we can make use of it everywhere in the world. The author measured the usable time and took position fixes from three fixed stations in Japan in order to evaluate the positioning accuracy of GPS, firstly by the difference in the time of the year and, secondly by the difference in location between the stations in 1988. I was able to receive positioning signals from only 6 or 7 satellites, but in July 1991, 14 GPS satellites became available. The results obtained are summerized as follows: 1) The usable time was 7~9 hours from only 6~7 satellites. 2) In the case of the former, the time zone of position fixes varied with the time of the year and there were a little differences of the accuracy of position fixes except 3H(three dimensiomal high level positioning). In the case of the latter, there were not obvious locality differences in 3D(three dimensional positioning). But the positioning errors and number of data varied on each level in 2D(two dimensiomal positioning), although the positioning errors were smaller than 0.1 nautical mile. 3) Th standard deviations of Dep(departure) were larger than tat of D.lat(difference of latitude), and varied widely to the east and west. But the standard deviations were smaller than 100 meters.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.36 no.6
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• pp.629-639
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• 2018

In this study, the application of the single beam echosounder and multi beam echosounder was analyzed for the Youngsan river, from the Juksanbo to the Juksan bridge, length of 840m, width 230m and area $0.16km^2$. A single beam echosounder and a multi beam echosounder are mounted on an USV (Unmanned Surface Vessel), and each data is acquired. Then, TIN (Triangular Irregular Network) is created and the grid depth of 10m intervals is extracted. The grid depth of the single beam echo sounder and the grid depth of the multi beam echo sounder were overlapped to compare the two data. As a result of analysis using 5,024 data, the mean depth difference was 0.0319m and the standard deviation was 2.4095m. The river bed shape was similar to each other. If the multi-beam echo sounder is regarded as the standard, the volume difference of the stream is $161,882m^3$. With a multi-beam echo sounder installed, the operating distance increased by approximately 55% to 4595.85m, and the operating time increased by approximately 59% to approximately 47%.

• The Korean Journal of Petroleum Geology
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• v.11 no.1 s.12
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• pp.9-17
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• 2005

In the main target area of the block II, Targe-scale faults occur below the unconformity developed around 1 km in depth. The contrast of seismic velocity around the unconformity is generally so large that the strong multiples and the radical velocity variation would deteriorate the quality of migrated section due to serious distortion. More than 15 kinds of data processing techniques have been applied to improve the image resolution for the structures farmed from this active crustal activity. The bad and noisy traces were edited on the common shot gathers in the first step to get rid of acquisition problems which could take place from unfavorable conditions such as climatic change during data acquisition. Correction of amplitude attenuation caused from spherical divergence and inelastic attenuation has been also applied. Mild F/K filter was used to attenuate coherent noise such as guided waves and side scatters. Predictive deconvolution has been applied before stacking to remove peg-leg multiples and water reverberations. The velocity analysis process was conducted at every 2 km interval to analyze migration velocity, and it was iterated to get the high fidelity image. The strum noise caused from streamer was completely removed by applying predictive deconvolution in time space and ${\tau}-P$ domain. Residual multiples caused from thin layer or water bottom were eliminated through parabolic radon transform demultiple process. The migration using curved ray Kirchhoff-style algorithm has been applied to stack data. The velocity obtained after several iteration approach for MVA (migration velocity analysis) was used instead or DMO for the migration velocity. Using various testing methods, optimum seismic processing parameter can be obtained for structural and stratigraphic interpretation in the Block II, Yellow Sea Basin.

• The Korean Journal of Pesticide Science
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• v.14 no.3
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• pp.284-288
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• 2010

A series of experiments was carried out for selecting insecticides and determining proper spraying time to control pea weevil (Bruchus pisorum Linnaeus) in Jeonnam area. In the field trial two times spray with diazinon, carbaryl, imidacloprid, spinosad, etofenprox, clorpyrifos-methyl showed good control effect and threetimes spray showed the better control effect. The second spray (spraying on 10th of May) took the major role of insecticide effectiveness expression for controlling pea weevil. Further trial for selecting insecticides among organophosphates to control pea weevil in lab was conducted and every organophosphate insecticide tested was very effective to pea weevil even at the concentration of one forth of its recommending concentration.

• Journal of the Mineralogical Society of Korea
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• v.22 no.2
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• pp.129-138
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• 2009

The XRF core scanner was used, to analyze high resolution chemical elements in deep sea sediment cores from Clarion-Clipperton fracture zone of the northeastern Pacific. Comparison of data estimated by the XRF core scanner with ICP-AES showed relatively weak correlation coefficients between elements (especially Ba, Pb, Sr, Zr) except for Mn contents ($r^2$ > 0.89). However down-core variations of most elements seemed to be well matched each other and furthermore, XRF core scanner data reflected changes of sedimentary facies characterized by sediment colors. Mn/Al ratio dramatically changed at boundaries of facies in BC08-02-05 and BC08-02-13 but progressive changes occured in BC08-02-02, BC08-02-09 and BC08-02-10 where the sediments have been affected by bioturbations. The difference of Mn/Al ratio in each facies (Facies I, Facies II, Facies III) has been caused by redox condition of depositional environment. Vertical change of Mn/Al ratio were divided into two types probably affected by activities of benthic organisms in the study area.

• The Korean Journal of Ecology
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• v.26 no.3
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• pp.129-134
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• 2003

Amounts of CO₂ fixed by net primary production and released by soil respiration were determined on big-cone pine plantation. Net primary production, which was determined by allometric method, was converted into CO₂. CO₂ evolution in forest ecosystems are mainly through soil and root respiration. In order to separate root respiration from soil respiration, root-free sites were made in stand. Litter removal sites were prepared to estimate CO₂ evolution through litter layer. Respiration was measured at every two weeks intervals from April 2001 through April 2002, and soil temperature and soil moisture were measured at the same time. Net primary production of this big-cone pine plantation was 25.7 t·ha/sup -1/·yr/sup -1/. The amount of CO₂ fixed by this plantation was 42.5 t CO₂·ha/sup -1/·yr/sup -1/, The amount of CO₂ released by soil respiration was 5.0 t CO₂·ha/sup -1/·yr/sup -1/. The relative contribution of root respiration and litter layer respiration to total respiration was 46% and 32%, respectively. Net amount of fixed CO₂ was 37.5 t CO₂·ha/sup -1/·yr/sup -1/ in this big-cone pine plantation. From this result, this big-cone pine plantation play a carbon sink source from the atmosphere.

• The Journal of Engineering Geology
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• v.18 no.4
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• pp.371-379
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• 2008

In this study, seismic elastic wave and dynamic elastic modulus properties are investigated by down-hole seismic tests that were applied to the 11 gneiss area. The research results show that the realtionship between the two properties are $V_s=0.5589{\times}V_p$ in gneiss. The relationship between the two properties are separated into two groups. Group 1 is influenced mainly by the specific gravity of rock, but group 2 is influenced mainly by the joint aperture. As weathering progresses, group 1 clearly shows a decreasing tendency. In fresh and slightly weathered rock-mass, correlations between $V_p$ and dynamic elastic modulus is expressed in linear line but in moderately-highly weathered rock-mass, correlations between $V_p$ and dynamic elastic modulus is expressed curve as a quadratic function. Correlations between $V_s$ and dynamic elastic modulus are analyzed similar with a $V_p$ case.

• Geophysics and Geophysical Exploration
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• v.9 no.1
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• pp.129-138
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• 2006

Helicopter-borne aeromagnetic surveys at two different times separated by three years were conducted to better understand the shallow subsurface structure of the Vulcano and Lipari volcanic complex, Aeolian Islands, southern Italy, and also to monitor the volcanic activity of the area. As there was no meaningful difference between the two magnetic datasets to imply an apparent change of the volcanic activity, the datasets were merged to produce an aeromagnetic map with wider coverage than was given by a single dataset. Apparent magnetisation intensity mapping was applied to terrain-corrected magnetic anomalies, and showed local magnetisation highs in and around Fossa Cone, suggesting heterogeneity of the cone. Magnetic modelling was conducted for three of those magnetisation highs. Each model implied the presence of concealed volcanic products overlain by pyroclastic rocks from the Fossa crater. The model for the Fossa crater area suggests a buried trachytic lava flow on the southern edge of the present crater. The magnetic model at Forgia Vecchia suggests that phreatic cones can be interpreted as resulting from a concealed eruptive centre, with thick latitic lavas that fill up Fossa Caldera. However, the distribution of lavas seems to be limited to a smaller area than was expected from drilling results. This can be explained partly by alteration of the lavas by intense hydrothermal activity, as seen at geothermal areas close to Porto Levante. The magnetic model at the north-eastern Fossa Cone implies that thick lavas accumulated as another eruption centre in the early stage of the activity of Fossa. Recent geoelectric surveys showed high-resistivity zones in the areas of the last two magnetic models.

• Pediatric Infection and Vaccine
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• v.25 no.3
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• pp.123-131
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• 2018

Purpose: Cytomegalovirus (CMV) infection is mostly asymptomatic but can be detrimental to certain hosts. We investigated changes of CMV seroprevalence in Koreans before and after the year 2000. Methods: We reviewed laboratory values of patients who were tested for CMV immunoglobulin G (IgG) at Samsung Medical Center, Seoul, Korea, from January 1995 to December 2015. Changes in seroprevalence were analyzed by gender, age, region, and tested year period (period 1, 1995-2005 vs. period 2, 2006-2015). Results: Overall CMV seropositivity was 94.1% (10,900/11,584). There was no significant difference for CMV seropositivity among the two periods (94.2% vs. 94.1%) (P=0.862). CMV seropositivity in the 11 to 20-year age group in period 2 (78.8%) was significantly lower than that of period 1 (89.9%) (P=0.001). The seropositivity of individuals aged 31-40 years (97.4%) was significantly higher than that of younger age groups (P<0.001) and lower than that of older age groups (P<0.001). Of 2,441 females of reproductive age (from 15 to 49), CMV seropositivity was 97% (2,467/2,441). The seropositivity in women aged 20-24-years was higher than that of men in the same age group (97.6% vs. 85.6%, P=0.003). No significant difference was observed among different regions. Conclusions: Overall CMV seropositivity of Koreans was estimated to be 94% and the average seropositivity of reproductive women was 97%. Monitoring of the changes in seroprevalence including the reproductive age group is needed in the future.

• Journal of the Korean Wood Science and Technology
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• v.48 no.2
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• pp.206-216
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• 2020

This study was conducted to analyze the sap flow and composition by tapping date in Acer akamotoanum from an artificial forest in the City of Jinju. The sap was collected from five saplings (diameter at breast height10-20 cm) in two phases with an interval of a month. During phase 1 (January 10, 2019 - February 9, 2019) with daily mean temperature of 1.16±2.15℃, 60.59 liters of sap was collected over 32 days. Phase 2 (February 12, 2019 - February 22, 2019) with daily mean temperature of 2.55±1.30℃ yielded 13.38 liters of sap over 11 days, which was a reduction to 22% of the total sap flow in phase 1. The analysis of sugar composition in the collected sap from phase 1 and 2 showed that sucrose concentration was 2.5% at its highest during the earlier days of collection and decreased to 0.8% at the end. Glucose and fructose concentrations were measured near 0, and were lower than sucrose concentration. The most prominent inorganic elements in the collected sap were potassium (41.69 - 89.75 mg/kg), calcium (24.66 - 48.14 mg/kg) and magnesium (10.18 - 27.25 mg/kg). The contents of sucrose and inorganic components between the samples collected from phase 1 and 2 did not show significant differences. The sap flow amounts of A. okamotoanum from different tapping periods showed a notable variation, but there were no significant differences in the contents of sugar or inorganic elements.