• Journal of the Korean GEO-environmental Society
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• v.10 no.6
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• pp.117-123
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• 2009

The mechanical behavior of a micropile due to horizontal load has not yet clearly identified in Korea. It has generally estimated from that of a traditional pile because there is no standard method even though it has shorter length. To tell the truth, its behavior is very different from a traditional pile's. Specifically, it is general fact that horizontal resistance of earth is one of the main factors to control the mechanical behavior of micropile. To this reason, a laboratory model has been made in this study to estimate the behavior of a micropile which loaded increasingly horizontally. The laboratory model has been designed to estimate both the behavior of load to displacement and skin friction to displacement. And the analysis of the latter was compared with the solution of strain wedge model. In the end, it was proved that the mechanical behavior of a micropile should be estimated from considering the horizontal resistance of earth.

• The KSFM Journal of Fluid Machinery
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• v.10 no.5
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• pp.54-63
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• 2007

A barrel is a high length-to-diameter ratio cylinder that is influenced by environmental factors such as sunlight, precipitation, wind and clouds. Cross-barrel temperature differences caused by uneven heating or cooling lead to thermal deformation that degrades accuracy. Therefore, a barrel is covered by thermal shrouds to minimize the type of thermal deformation, "fall-of-shot". In this paper, an analytical and experimental study is presented to design the thermal shrouds for a gun barrel and to evaluate the thermal shroud effect. First, an analytical study on the thermal shroud effect to minimize thermal deformation of a gun barrel by sunlight and wind is performed. The coupled analysis of thermal fluid dynamics of the air flow between a barrel and thermal shrouds and thermal stresses of a barrel Is performed to clarify both the thermal shroud effect and the drift in gun muzzle orientation by thermal deformation. Second, experiments are carried out to test and evaluate the thermal shroud effect on the performance of a gun barrel. The drift in gun muzzle orientation against the solar radiation is confirmed by the experiments, and the results well agree with the analytical estimation. Third, three principal design factors that are presumed to have an effect on the performance of the thermal shrouds are also analyzed; sorts of shroud materials, wall-thickness of thermal shrouds, and distance of the gap between a barrel and thermal shrouds.

• Journal of the Korean Society of Propulsion Engineers
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• v.21 no.4
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• pp.1-11
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• 2017

TPTF (Turbopump Real Propellant Test Facility) at Naro Space Center has used alcohol burner system to simulate the gas flow of gas generator of liquid rocket engine. During the test at TPTF, the temperature and pressure at turbine inlet were smoothly increased while those of the gas generator of engine were constant. Present research developed a simulation code for the burner and the piping system and applied to the system. The calculation results were in good agreement with the test, and confirmed quantitatively that the non-steadiness is due to the heat transfer of the pipe. While the insulation of the pipe is ineffective, the length has a large impact on the turbine inlet condition. The present research clarified the empirically estimation of test condition, and can be applied to determination of the following test conditions.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.5
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• pp.604-610
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• 2018

Recently, due to the rapid growth of the leisure industry, demand for small-scale flotation and mooring pontoon platforms has been increasing rapidly. Standard rules for the design and structural safety of such structures have become necessary. This paper provides criteria that can be referenced when designing pontoon platforms, and also introduces structural safety evaluation procedures. In this study, the structural safety and stability of a 15-meter pontoon platform were investigated through structural design and finite element analysis. For platforms of less than 10 meters in length, a simple structural calculation can be used, but for platforms over 10 meters, a detailed structural strength review must be considered to meet safety guidelines defined in existing regulations. The structural strength of the initial design was examined and its structural safety was verified. For future research, it is an evaluative system was developed that can be used to examine the various loading conditions during design.

• The Korean Journal of Mycology
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• v.37 no.1
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• pp.55-59
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• 2009

The mushroom takes in charge of decomposer in ecosystem and its production is important indicator for sounded ecosystem function. To determine standing crop of basidiocarps(fruit body of mushroom), a weight must be measured by harvesting mushroom individual in the field. But this method has profound affection on the basidiocarps population or its surrounding condition due to habitat destruction. Thus, in this study, without harvesting any mushroom in the field, we developed allometric equation using some morphological parameters to estimate standing crop biomass of basidiocarps. Lentinula edodes, Pleurotus ostreatus, Flammulina velutipes and Conocybe tenera were used for allometry. Morphological variables of the mushroom were pileus diameter, pileus area, stipe length and stipe thickness. Consequently, all the experimental mushrooms species showed significantly correlation in biomass estimation of basidiocarps from allometric equation (p<0.05). As a result of this research, the standing biomass of the basidiocarps could be indirectly estimated with proportional expression, allometric equation drived from morphological characters.

• Geophysics and Geophysical Exploration
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• v.7 no.1
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• pp.62-69
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• 2004

The objective of this study is to estimate the distribution of a zone disturbed by excavation (EDZ) around tunnels that have been excavated at about 500 m depth in pre-Tertiary hard sedimentary rock. One of the most important tasks is to evaluate changes in the dynamic stability and permeability of the rock around the tunnels, by investigating the properties of the rock after the excavation. We performed resistivity and acoustic tomography using two boreholes, 5 m in length, drilled horizontally from the wall of a tunnel in pre-Tertiary hard conglomerate. By these methods, we detected a low-resistivity and low-velocity zone 1 m in thickness around the wall of the tunnel. The resulting profiles were verified by permeability and evaporation tests performed at the same boreholes. This anomalous zone matched a high-permeability zone caused by open fractures. Next, we performed resistivity monitoring along annular survey lines in a tunnel excavated in pre-Tertiary hard shale by a tunnel-boring machine (TBM). We detected anomalous zones in 2D resistivity profiles surrounding the tunnel. A low-resistivity zone 1 m in thickness was detected around the tunnel when one year had passed after the excavation. However, two years later, the resistivity around the tunnel had increased in a portion, about 30 cm in thickness, of this zone. To investigate this change, we studied the relationship between groundwater flow from the surroundings and evaporation from the wall around the tunnel. These features were verified by the relationship between the resistivity and porosity of rocks obtained by laboratory tests on core samples. Furthermore, the profiles matched well with highly permeable zones detected by permeability and evaporation tests at a horizontal borehole drilled near the survey line. We conclude that the anomalous zones in these profiles indicate the EDZ around the tunnel.

• Journal of the Korean Society for Railway
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• v.15 no.5
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• pp.429-435
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• 2012

The HEMU-430X is a world-class railway vehicle which aimed the maximum speed of 430km/h and the operation speed of 370km/h. To maintain high-speed operation condition over 300km/h, various requirements for satisfy exist. However, one of the most important things is a reliable supply of electricity. Especially, the dynamic interaction between the pantograph and overhead contact line at high-speed is a significant matter to pre-evaluate. In this paper, using the dynamic interaction analysis program, current collection performance of the HEMU-430X was investigated. Firstly, based on the international standard, performance of the original specifications was evaluated. In addition, through study on changes in tension and span length, improvement of the performance was considered.

• Journal of the Korean Society of Food Science and Nutrition
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• v.29 no.6
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• pp.1025-1029
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• 2000

This study was conducted to investigate whether a DNA comet assay could be applied for identifying irradiated pork and beef. Pork and beef were irradiated with Co-60 gamma rays at 0.1, 0.3, 0.5, 0.7 and 1.0 kGy, and stored in a freezer Cells separated from the samples were embedded in agarose gel on a slide, dissolved in a lysis solution, and electrophoresed at 2 V/cm for 2.0 min by horizontal electrophoesis. The cells were then stained with a silver staining in order to visualize the DNA using a micro-scope. The DNA fragments of the irradiated cells stretched or migrated out of the cells and formed tails towards the anode, giving the appearance of comets, while unirradiated cells formed very short or no tails. The distance of DNA migration increased with irradiation dose. Since the statistical analysis showed a significant correlation between tail length and irradiation dose, a DNA comet assay could provide not only identification but also estimation of the irradiation dose for irradiated beef and pork.

• Journal of The Korean Society of Agricultural Engineers
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• v.55 no.6
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• pp.101-112
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• 2013

Shuttle Radar Topography Mission Digital Elevation Model (SRTM DEM) offers opportunities to make advances in many research areas including hydrology by providing near-global scale elevation measurements at a uniform resolution. Its wide coverage and complimentary online access especially benefits researchers requiring topographic information of hard-to-access areas. However, SRTM DEM also contains inherent errors, which are subject to propagation with its manipulation into analysis outputs. Sensitivity of hydrologic analysis to the errors has not been fully understood yet. This study investigated their impact on estimation of hydrologic derivatives such as slope, stream network, and watershed boundary using Monte Carlo simulation and spatial moving average techniques. Different amount of the errors and their spatial auto-correlation structure were considered in the study. Two sub-watersheds of Geum and Deadong River areas located in South and North Korea, respectively, were selected as the study areas. The results demonstrated that the spatial presentations of stream networks and watershed boundaries and their length and area estimations could be greatly affected by the SRTM DEM errors, in particular relatively flat areas. In the Deadong River area, artifacts of the SRTM DEM created sinks even after the filling process and then closed drainage basin and short stream lines, which are not the case in the reality. These findings provided an evidence that SRTM DEM alone may not enough to accurately figure out the hydrologic feature of a watershed, suggesting need of local knowledge and complementary data.

• The Journal of Sustainable Design and Educational Environment Research
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• v.14 no.2
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• pp.37-44
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• 2015

The purpose of this study is to propose the calculation model of CCTV monitor size for school. Literature review analyzed the concept and technical characteristics of CCTV system including equation of object size calculation. Case study showed that the sizes of CCTV monitors installed in the security offices of the six object schools were 19 inches on average. And the numbers of monitor screen partitions were at least 12 on average. Due to too many partitions in small monitors of approximately 19 inches, the faces of the objects of filming in each screen could not be properly identified. Experimental test presented that the vertical length of face image clearly recognized on the screen is at least 20mm. Based on the result, this paper developed the equation for calculating monitor size. Pilot test said that 27inch Monitor is needed for 4 screens. The practitioners of school districts and schools can make appropriate CCTV system environments considering the their own CCTV system conditions.