• Geophysics and Geophysical Exploration
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• v.12 no.3
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• pp.255-262
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• 2009

Conventionally, vertical-seismic-profiling (VSP) survey that provides high-resolution information has mainly performed to obtain the exact depth of the gas hydrate-bearing sediment, which is one of the key factors in the development of the gas hydrate. In this study, we extracted interval velocities and created corridor stacks from the first domestic zero-offset VSP data, which were acquired with three component receivers at UBGH09 borehole in Ulleung Basin where gas hydrate exists. Then we compared the corridor stacks with a CMP stacked section from surface seismic data. First of all, we converted the signals recorded with three component receivers to true vertical and horizontal components by phase rotation, and divided the data into direct waves and reflected waves by wavefield separation processing. The trend of the interval velocity extracted from the zero-offset VSP was similar to that of the sonic log obtained at the same borehole. Because the interval velocity of the gas hydrate-bearing sediment above the BSR was high, and it decreased suddenly through the BSR, we could infer that free gas is accumulated below the BSR. The results of comparing the corridor stacks to the CMP stacked section of the surface seismic data showed that most reflection events agreed well with those in the surface CMP stacked section and that the phase-rotated VSP data corresponded better with the surface seismic data than the VSP data without phase rotation. In addition, by comparing a corridor stack produced from the transverse component with the CMP stacked section of the surface seismic data, we could identify PS mode-converted reflections in the CMP stacked section.

• Korean Journal of Computational Design and Engineering
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• v.8 no.4
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• pp.278-288
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• 2003

Presented in this paper is a numerical method for calculating the intersection points between Z-map vectors and the tool swept surface for circularly moving filleted-end mills. In numerically controlled(NC) machining simulation for large moulds and dies, a workpiece is frequently approximated as a set of z-axis aligned vectors, called Z-map vectors, and then the machining processes can be simulated through updating the Z-map with the intersection points. Circular motions are typically used for machining the free-form surfaces. For fast computation, we express each of intersection points with a single-variable non-linear equation and calculate the candidate interval in which the unique solution exists. Then, we prove the existence of a solution and its uniqueness in this candidate interval. Based on these properties, we can effectively apply numerical methods to finally calculate the solution of the nonlinear equation within a given precision. Experimental results are given for the case of a TV monitor and the hood of a car.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.27 no.3
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• pp.223-228
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• 1982

Experiments were conducted to study the interrelationships between root development of rice plant and water managements at saline paddy field where has been grown rice plant for 3 years, and to compare the root development between two fields, saline and matured. Under the conditions of non interval and two day interval flooding at saline paddy fields, root systems developed well at surface soil, however, root systems developed well and distributed evenly through surface and sub-soil at saline field where underground drainage was performed, and at matured field. Root developments at field flooded with no interval and with two-day interval were poor as compared with those of saline paddy field of underground drainage and matured field. Regardless of water managements and fields, the ratio of stunted crown roots developed after panicle fromation stage was higher than that developed at early or middle growth stage.

• Journal of Korea Entertainment Industry Association
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• v.14 no.6
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• pp.191-199
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• 2020

Younger generations use a variety of visual media, such as smartphones, televisions, and computers. Due to the development of visual media, the health of eye was weakening. Therefore, this study aimed to investigate the effects of eye health and dynamic visual activity on eye muscle stimulation with eye movement and therapeutic massage in university students. 38 university students in their 20s were divided into a control group(18) and an experimental group(20). The experimental group performed eye movement and therapeutic massage every 30 minutes for 5 times a week for 4 weeks. Ocular fatigue, maximal blinking interval, ocular surface temperature, and dynamic visual activity were measured before and after 4 weeks. Ocular fatigue was decreased significantly after 4 weeks (p<.05), and maximal blinking interval was increased significantly after 4 weeks (p<.05). Ocular surface temperature was not showed a significant difference after 4 weeks (p>.05), and dynamic visual activity was increased significantly after 4 weeks (p<.05). Therefore, eye movement and therapeutic massage are recommended for the improvement of eye function and eye health. It is expected to be used as research data to restore and prevent for eye health.

• Journal of Ocean Engineering and Technology
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• v.15 no.4
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• pp.86-91
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• 2001

In lateral ground flow, slope stability, and land slide problems, H-piles have been often used for a horizontally deforming ground to prevent the failure of mass of soil in a downward and outward movement of a slope. Here, Theoretical equations are derived to estimate the lateral force, assuming that the Mohr-coulomb's Plastic states occures in the ground just around H-piles. In this study, the mechanism of lateral force acting on passive pile that is in a row, situated in the ground undergoing plastic deformation was discussed, and its theoretical analysis was carried out considering the interval between H-piles. The solution of the theoretical equation derived from here showed resonable characteristic for constants of soil as well as for the interval, widths, and heights of H-pile.

• Journal of Ocean Engineering and Technology
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• v.16 no.6
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• pp.44-48
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• 2002

In lateral ground flow, slope stability, and land slide problems, H-piles have often been used, on a horizontally deforming ground, to prevent the failure of mass of soil in a downward and outward movement of a slope. Here, theoretical equations are derived to estimate the lateral force, assuming that the Mohr-Coulomb's plastic states occur in the ground, just around H-piles. In this study, some model experiments were performed to check the lateral forces determined from theoretical equations, using several pile widths, heights and various interval ratios between H-piles for sand specimens. The solution of the theoretical equation, derived from previous studies, showed reasonable characteristics for constants of soil, as well as for the interval, widths, and heights of H-Pile.

• 한국석유지질학회:학술대회논문집
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• autumn
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• pp.2-16
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• 1999

This study includes structural analysis of the northern Pattani Basin, areal description of depositional facies, and their spatial relationships using 3-D seismic and well data. Well log data indicate that the representative depositional facies of the studied intervals are sandy, fluvial, channel-fill facies encased in shaly floodplain deposits. Seismic responses were predicted from a synthetic seismogram using a model of dominant depositional facies. Peak-to-trough amplitude and instantaneous frequency seismic attributes are used in depositional facies interpretation. Three Intervals A, B and C are interpreted on the successive stratal surfaces. The shallowest interval, A, is the Quaternary transgressive succession. Each stratal surface showed flow pattern variation of fluvial channel facies. Two transgressive cycles were identified in interval A. Interval B also indicated fluvial facies. Depositional facies architectures are described by interpreting seismic attributes on the successive stratal surfaces.

• Journal of Dental Rehabilitation and Applied Science
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• v.19 no.4
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• pp.309-315
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• 2003

When the exposure surface of restoration is brushed with various toothpaste in the mouth, wear or undesirable surface deposit of restoration can occur. Surface change of gallium alloys according to brushing and toothpaste may directly affect oral hygiene. The aim of this study was to evaluate the surface alterations of Gallium alloys during tooth brushing with different prophylactic agents. Two gallium-alloys and an amalgam as a control were investigated. Without and with brushing were applied with three kinds of prophylactic agents on the sample for 0, 1, 5, 10, 60 and 360 minutes. At each time interval, surface roughness was recorded by a profilometer and some pictures were taken by a SEM. All results were analyzed by the one-way ANOVA, followed by Tukey multiple comparisons and the simple linear regression analysis. The results indicate that gallium alloys are more susceptible to surface degradation during tooth brushing than amalgam with respect to the specific prophylactic agent used.

• Journal of Korean Society for Atmospheric Environment
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• v.32 no.4
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• pp.384-393
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• 2016

In this study, two kinds of industrial filter bags were tested for their filtration performance to apply the existing bag filter systems. Experimental variables were examined for pressure drop, cleaning interval, residual pressure drop, cleaning efficiency, fractional grade efficiency, total collection efficiency according to the filter bag structure. According to these results, the filter bags tested in this study demonstrated good performance in dust collection. This was also true for the double surface filter bag. The lifetime was longer than the round type filter bag because the filtration area was more than 1.6 times wider and the filter quality factor was much higher. Therefore, double surface filter bags are suggested to be used in order to increase filtration performance of the bag filter systems.

• Proceedings of the KSRS Conference
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• v.2
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• pp.816-819
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• 2006

One of the most difficult parameters to measure in the sea is current speed and direction. Recently, efforts are being made to estimate the ocean current vectors by utilizing sequential satellite imageries. In this study, we attempted to estimated sea surface current vector (sscv) by using satellite ocean color imageries of SeaWifs around the Korean Peninsula. This ocean color image data has 1-day sampling interval and spatial resolution of 1x1 km. Maximum cross-correlation method is employed which is aimed to detect similar patterns between sequential images. The estimated current vectors are compared to the surface geostrophic current vectors obtained from altimeter of sea level height data. In utilizing the color imagery data, some limitations and drawbacks exist so that in warm water region where phytoplankton concentration is relatively lower than in cold water region, estimation of sscv is poor and unreliable. On the other hand, two current vector fields agree reasonably well in the Korean South Sea region where high concentration of chlorophyll-a and weak tide is observed. In the future, with ocean color images of shorter sampling interval by COMS satellite, the algorithm and methodology developed in the study would be useful in providing the information for the ocean current around Korean Peninsula.