• The Journal of Engineering Geology
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• 제17권1호
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• pp.101-113
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• 2007

A landslide was occurred due to soil cutting for construction to expand the Donghae express highway in Dong-hae-City, Korea. The total area of the landslide was about $9,550m^2$ with 100 m of width and 87m of height. The landslide was occurred due to the internal factor of the unstable geological structure including the clay layer and the external factor of continuous heavy rainfalls. As the result of field instrumentation during the landslide, the horizontal displacement of the slope ground increases with increasing the accumulated rainfall by continuous rainfall during the rainy season. Also, the depth of sliding failure was decided by the horizontal displacement distribution during landslide occurrence. It makes sure that the horizontal displacement starts from the depth of sliding failure and the depth of sliding failure matches well with the location of the clay layer. As the slope stability analysis using Bishop's Simplified Method at the landslide area, the safety factor of slope during the rainy season was 0.53. This safety factor of slope was enough to trigger the landslide at this area. The depth of sliding failure obtained by analytical method matches well with the depth of the clay layer.

• Journal of Oral Medicine and Pain
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• 제30권4호
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• pp.411-426
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• 2005

The purpose of this study was to investigate the effects of occlusal condition and clenching level on the mandibular torque rotational movement. For this study, healthy 14 men without any symptoms and signs of temporomandibular disorders were selected. Mandibular torque rotational movement was observed in each circumstance of combination of three occlusal conditions such as natural dentition, with wafer of 3.6 mm thickness, and wafer with resin stop of 14 mm thickness total during hard biting of bite stick at maximum voluntary contraction(MVC) and 50% of MVC level of surface EMG activity of masseter muscle. Electromyographic activity and mandibular torque rotational movement were observed using BioEMG and BioEGN in $BioPak^{(R)}$ system. Each biting movement in each circumstance was composed of clenching one time and hard biting of wooden stick two times. The observed items were opening distance, velocity and amount of torque rotational movement in mandibular movement, and the data were statistically processed with $SPSS^{(R)}$ windows (ver.10.0). The results of this study were as follows: 1. There were no differences in the mandibular movement distance between those value in both biting sides, and between those in both clenching forces, but the mandibular velocity showed a different results by clenching force. For the amount of torque rotational movement, there were no difference in the value of the frontal plane but some significant difference was in the value of the horizontal plane by biting side. 2. The mandibular movement distance and the mandibular velocity in both planes were higher by maximum voluntary contraction than those by half maximum voluntary contraction, and amount of torque rotational movement in the horizontal plane was also increased by maximum voluntary contraction. 3. The opening distance in both planes were decreased with the increase of vertical dimension of occlusion, namely, by the occlusal appliances, and this pattern was also showed in the mandibular velocity in case of hard biting by maximum voluntary contraction. However, the amount of torque rotational movement were not different by the increase of vertical dimension of occlusion. 4. The value of angle and distance of the torque rotational movement in the hard biting of wooden stick were generally higher than those in the clenching without wooden stick in both planes without regard to occlusal conditions and/or clenching forces.

• Journal of the Korean Geotechnical Society
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• 제20권6호
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• pp.119-126
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• 2004

Behaviour of soil nailed walls in Korea has been analysed based on a number of field measurements. The investigation has included interface shear strength development at the nail-soil interface from pull-out tests, lateral ground displacements, tensile force distributions along soil nails and mobilised interface shear stress distributions. Insights into the soil nailed wall behaviour based on the shear transfer mechanism at the soil-nail interface and partial mobilisations of the interface shear strength, governed by relative shear displacement, are reported and discussed. It is expected that results from the current research can provide relevant parameters required for preliminary design of soil nailed walls in Korea.

• The Journal of the Acoustical Society of Korea
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• 제22권8호
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• pp.652-659
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• 2003

High-frequency(40∼120 kHz) reflection loss measurements on the water-sandy sediment with a flat interface were conducted in a water tank for various grazing angles. The water tank(5×5×5 m) was filled with a 0.5 m-thick-flat bottom of 0.5ø-mean-grain-size sand. Reflection losses, which were experimentally obtained as a function of grazing angle and frequency, were compared with the forward loss model, APL-UW model (Mourad & Jackson, 1989). For frequencies below 60 kHz, the observed losses well agree with the reflection loss model, however, in cases for frequencies above 70 kHz, the observed losses are greater by 2∼3 dB than the model results. The model calculation, which does not fully account for the vertical scale of roughness due to grain size, produce less bottom losses compared to the observations that correspond to large roughness based on the Rayleigh parameter in the wave scattering theory. In conclusion, for the same grain-size-sediment, as frequencies increase, the grainsize becomes the scale of roughness that could be very large for the frequencies above 70 kHz. Therefore, although the sea bottom was flat, we have to consider the frequency dependence of an effect of roughness within confidential interval of grain size distribution in reflection loss model.

• The Journal of Engineering Geology
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• 제19권2호
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• pp.191-203
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• 2009

The effect of stabilizing piles on cut slopes is checked and the behavior of slope soil and piles are observed throughout the year by field measurements on the large-scale cut slopes. First of all, the behavior of the slope soil was measured by inclinometers during slope modification. Landslides occurred in this area due to the soil cutting for slope modification. The horizontal deformations of slope soil are gradually increased and rapidly decreased at depth of sliding surface. As the result of measuring deformation, the depth of sliding surface below the ground surface can be known. Based on the measuring the depth of the sliding surface, some earth retention system including stabilizing piles were designed and constructed in this slope. To check the stability of the reinforced slope using stabilizing piles, an instrumentation system was installed. As the result of instrumentation, the maximum deflection of piles is measured at the pile head. It is noted that the piles deform like deflection on a cantilever beam. The maximum bending stress of piles is measured at the soil layer. The pile above the soil layer is subjected to lateral earth pressure due to driving force of the slope, while pile below soil layer is subjected to subgrade reaction against pile deflection. The deflection of piles is increased during cutting slope in front of piles for the construction of soil nailing. As a result of research, the effect and applicability of stabilizing piles in large-scale cut slopes could be confirmed sufficiently.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• 제19권2호
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• pp.13-22
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• 2005

This research aimed to generate two points of daylighting application as follows: 1) providing daylight performance data with a variety of glazing materials for a large window and 2) designing and evaluating an experimental type of differentiated window. For this purpose, we compared the daylight and distribution performance of new defined type of window configuration to the conventional window counterpart with a variety of glazing materials. The comparison was made for a deep, south-facing perimeter zone with large window, without any interior obstruction. The conventional window is the base single homogeneous glass pane, where as the differentiated window uses of two different glazings; an upper daylight glazing with high visible transmission and lower view window with lower transmittal glass. The daylight performance data was translated into a ratio between outdoor illuminance and the interiors. The simulated analysis of the conventional window indicates that the interior light levels have been changed proportionally dependent on the transmittance of the applied glass. The comparison of daylight distribution analysis showed that the differentiated window has lots of photometric advantage by the optical function of upper daylight window. In particular, the contribution of higher daylight window into deep rear space must be stressed for daylighting application.

• Journal of Korean Society of Coastal and Ocean Engineers
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• 제16권2호
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• pp.83-91
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• 2004

The performance of wave control by a surface-mounted horizontal membrane is analyzed in the frame of linear potential theory. To employ the eigenfunction expansion method, the fluid domain is divided into two regions i.e. region without membrane and membrane-covered region. By matching the each solutions at boundaries of adjacent regions, the complete solution is obtained. The present analytical method solving the scattering problem directly gives the same results as Cho and Kim(1998)'s method solving the diffraction and the radiation problem separately. To verify the developed model, the model test with a surface-mounted horizontal membrane is conducted at the wave tank(36m${\times}$0.91m${\times}$l.22m). The analytic results are in good agreement with the experimental results. The reflection and transmission coefficients are investigated according to the change of membrane tension, length and incident frequencies.

• Journal of Energy Engineering
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• 제2권3호
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• pp.251-257
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• 1993

The purpose of this study is to obtain an improved interpretation of heat transfer phenomena between blocks and fluids in the parallel conducting plates. Flow is two-dimensional, incompressible steady laminar flow over rectangular blocks, representing finite heat source on parallel plate. Heat transfer phenomena, temperature of blocks and heat transfer into the flow field are investigated for different spacings between blocks and Reynolds numbers. Results indicate that Nusselt number on the far upstream corner of the block was higher than that of any part of the block. As Reynolds number and spacings of blocks increased, Nusselt number increased. The distribution of local Nusselt number on the top surface of the conducting plate is similar to the case with insulated plate. Temperature of the block which has heat source in half cubage was approximately twice as high as temperature of the block which has heat source in whole cubage. As Reynolds number and spacings of blocks increased, overall temperature decreased. The peak value of block temperature occurred at position shifted to the right or upper right from center. The maximum temperature of block can be expressed as a function of Reynolds number, spacings between blocks, position of maximum temperature of each block and then it is possible to predict the maximum temperature of blocks.

• Journal of the Korean Geosynthetics Society
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• 제10권4호
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• pp.11-18
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• 2011

In this study, the reinforcing effect of geogrids in the narrow backfill by sand was experimentally studied. In the model tests, the size of space and the slope of the cut off slope were varied out. The resultant and the distribution of lateral earth pressure were measured. Width of backfill space varied 10 cm, 20 cm, 30 cm at the lower wall level and angle of the cut off slope varied $90^{\circ}$, $75^{\circ}$, $60^{\circ}$. Geogrids were installed in the backfill. Measured results showed that the distribution of the lateral earth pressure due to the narrow backfill developed in a arching shape. And the earth pressure was reduced due to the reinforcement of the backfill by geogrid. geogrid helps reduction of lateral earth pressure.

• Journal of the Korea Academia-Industrial cooperation Society
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• 제17권4호
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• pp.400-413
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• 2016

The horizontal shear capacity when the flange of a steel girder is replaced with 80 MPa concrete is important for its structural safety. In this study, 6 specimens with different interface conditions were designed and fabricated based on the Limit State Design Code on Korean Highway Bridges and static tests were performed to measure the horizontal shear capacity. Not only the resistance factors of the stud shear connector, concrete and reinforcement, but also the surface conditions of the casing concrete and spacing of the horizontal shear reinforcements were used as the experimental variables. The experiments showed that the interfaces between the steel girder and the concrete flange have stronger joint performance than those between the concrete flange and deck slab. To ensure the composite action in the plastic zone, the conservative horizontal shear reinforcement is more important than the roughness in the concrete face.