• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.9
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• pp.46-51
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• 2013

In this paper, the optimum placement and shape of UHF antenna on the unmanned aerial vehicle (UAV) are analyzed by using the electromagnetic (EM) simulation on the various locations. The FEKO was used for the EM-simulation. In order to reduce the complexity of simulation and minimize the runtime and memory usage, the composite aircraft structure is simplified as the PEC model excluding the radome structure. The simulation was performed on the wing and ventral fin of UAV, and the antenna shape used the monopole, dipole, and bent monopole antennas. When the monopole antenna is mounted under the wing, two antennas need to be mounted under the right and left wings, and those antennas have to be switched as the direction of UAV wing to the line of sight (LOS) data-link (DL) ground antenna. In the case of mounting under the ventral fin, one antenna can be used regardless of the direction of UAV wing to the LOS DL ground antenna. Also, the antenna gain is improved by the blockage reduction. The antenna gain is further improved by using the bent monopole antenna. The optimum solution of UHF antenna placement and shape on UAV is to mount the bent monopole antenna under the ventral fin.

• Journal of the Korean GEO-environmental Society
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• v.11 no.3
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• pp.33-41
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• 2010

The rammed aggregate compaction pile method is widely used as soft ground improvement method because of the installed piles improve not only overall composite capacity but also discharge capacity. But the discharge capacity is declined when the clogging is generated due to the clay penetration into voids of rammed aggregate compaction pile with the time elapsed. The purpose of this study is to reduce the clogging problem occurred in rammed aggregate compaction pile constructed in the soft ground and to minimize voids of rammed aggregate compaction pile. The proper mixing ratio was determined which is based on the results of the large scale direct shear tests conducted to get strength and permeability as optimum mixing ratio of crushed stone and bottom ash. The test results indicated that the highest internal friction angle was obtained at 80:20 mixing ratio of crushed stone and bottom ash. The internal friction angle was declined when the mixing ratio of the bottom ash increased over 20%. The results of the clogging tests, presented that the mixture of 80:20 crushed stone and bottom ash is highest effective of clogging than ratio of pure crushed stone.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.3C
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• pp.149-158
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• 2008

This study is concerned with the characteristics of the behavior of drilled shafts with steel casing, a material that is used for large bridge foundations in Korea, and especially for weak submerged ground conditions. The effect of steel casing on bearing capacity of drilled shafts was also verified in this study. Three large drilled shafts with 1.8, 2.4, 3.0m diameter respectively were selected, and 3-D finite element analysis has been undertaken on the following three models: 1) drilled shafts without steel casing, 2) drilled shafts with steel casing, 3) steel-concrete composite drilled shafts. Interface element between concrete core and steel casing was taken into account, and ground conditions and load combinations were applied which had been considered in the fields. Detailed characteristics of the stress and displacement distributions were evaluated to understand the characteristics of the behavior of the drilled shafts. Based on the study performed, the steel casing used as load-carrying materials in the drilled shafts can reduce the horizontal and vertical displacement of drilled shafts by 32~37% and 15~19% respectively compared with drilled shafts without steel casing.

• Journal of the Korean Society of Food Science and Nutrition
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• v.37 no.1
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• pp.103-108
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• 2008

To develop an optimal composite recipe for a functional abalone porridge including abalone viscera, this study investigated the effects of added viscera on the physical, textural and sensory characteristics of the porridge. Several kinds of abalone porridge were prepared with 1%, 2%, 3%, 4%, or 5% of the viscera (w/w) and with round rice, half rice, or ground rice. pH of the porridge with half and ground rice decreased with increasing amounts of the viscera. TBARS value increased with increasing size of rice and increased with increasing amount of the viscera in the porridge with round and ground rice. Yellowness of the porridge increased significantly by the addition of the viscra. Among the four textural properties, consistency and firmness increased with increasing size of rice; in contrast, viscosity and cohesivness decreased with increasing size of rice. However, textural properties of the porridge were not significantly different by the addition of the viscera. In the sensory evaluation, sensory scores of the porridge with round and half rice were higher than with round rice for texture, taste and total. In conclusion, concerning overall sensory evaluation, round rice porridge with 2% viscera, half rice porridge with 3% viscera and ground rice porridge with 4% viscera showed the best results, implying that developing functional abalone porridge using the viscera may be worthy.

• Asian-Australasian Journal of Animal Sciences
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• v.27 no.7
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• pp.1050-1056
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• 2014

This study investigated the main factors influencing digester temperature and methods to reduce heat losses during the cold season in the subtropics. Four composite digesters (two insulated and two uninsulated) were buried underground to measure their internal temperature ($^{\circ}C$) at a depth of 140 cm and 180 cm, biogas production and methane ($CH_4$) concentration in biogas from August to February. In parallel the temperature of the air (100 cm above ground), in the slurry mixing tank and in the soil (10, 100, 140, and 180 cm depth) was measured by thermocouple. The influent amount was measured daily and the influent chemical composition was measured monthly during the whole experimental period. Seasonal variations in air temperature significantly affected the temperature in the soil, mixing tank and digester. Consequently, biogas production, which is temperature dependent, was influenced by the season. The main factors determining the internal temperature in the digesters were insulation with Styrofoam, air temperature and temperature of slurry in the mixing tank. Biogas production is low due to the cold climate conditions in winter in Northern Vietnam, but the study proved that storing slurry in the mixing tank until its temperature peak at around 14:00 h will increase the temperature in the digester and thus increase potential biogas production. Algorithms are provided linking digester temperature to the temperature of slurry in the mixing tank.

• Journal of The Korean Society of Agricultural Engineers
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• v.57 no.3
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• pp.109-120
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• 2015

Spatial heterogeneous characteristics of solar radiation energy from Climate Change gives rise to energy imbalance in the general ecological system including water resources. This study is to estimate the $CO_2$ flux of South Korea using Terra MODIS image and to assess the reliability of MODIS data from the ground measured $CO_2$ flux by eddy covariance flux tower data at 3 locations (two at mixed forest area and one at rice paddy area). The MODIS Gross Primary Productivity (GPP) product (MOD17A2), 8-day composite at 1-km spatial resolution was adopted for the spatial $CO_2$ flux generation. The MOD17A2 data by noise like cloud and snow in a day were tried to fill by Inverse Distance Weighted (IDW) method from valid pixels and the damping effect of MOD17A2 data were corrected by Quality Control (QC) flag. The MODIS $CO_2$ flux was estimated as the sum of GPP and Re (ecosystem respiration) by Lloyd and Taylor method (1994). The determination coefficient ($R^2$) between MODIS $CO_2$ and flux tower $CO_2$ for 3 years (2011~2013) showed 0.55 and 0.60 in 2 mixed forests and 0.56 in rice paddy respectively. The $CO_2$ flux generally fluctuated showing minus values during summer rainy season (from July to August) and maintaining plus values for other periods. The MODIS $CO_2$ flux can be a useful information for extensive area, for example, as a reliable indicator on ecological circulation system.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.9 no.1
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• pp.1-13
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• 2006

The recent environmental protection issue has diminished the supply of sand for soft ground improvements so much that the prices of sand have shown a sudden rise. Plastic material is one of substitutes for sand material, but plastic is nonperishable and doubtable if it has potential environmental hormone disrupting substances. Moderate-priced natural fiber drain board made with coconut coir and jute filter are in the spotlight recently as an alternative material for sand and plastic drain board etc. Natural fiber drain has not only competitive price but also a characteristic of assimilation into the soils after finishing of its own function. Discharge capacity of the fiber drain board evaluated by triaxial type discharge capacity test was relatively lower than that of plastic drain board. Nevertheless, settlement and pore pressure dissipation behaviors of the fiber drain board and the plastic drain board which were installed in the clayey soil during the composite discharge capacity test were almost similar. It was also found that biodegradation of the fiber drain board was in progress until 18 month after installation in the clayey soil, but they had still enough engineering properties to use at field.

• Advances in concrete construction
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• v.9 no.3
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• pp.313-326
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• 2020

Glass fiber-reinforced polymer (GFRP) bars have been introduced as an effective alternative for the conventional steel reinforcement in concrete structures to mitigate the costly consequences of steel corrosion. However, despite the superior performance of these composite materials in terms of corrosion, the effect of replacing steel reinforcement with GFRP on the seismic performance of concrete structures is not fully covered yet. To address some of the key parameters in the seismic behavior of GFRP-reinforced concrete (RC) structures, two full-scale beam-column joints reinforced with GFRP bars and stirrups were constructed and tested under two phases of loading, each simulating a severe ground motion. The objective was to investigate the effect of damage due to earthquakes on the service and ultimate behavior of GFRP-RC moment-resisting frames. The main parameters under investigation were geometrical configuration (interior or exterior beam-column joint) and joint shear stress. The performance of the specimens was measured in terms of lateral load-drift response, energy dissipation, mode of failure and stress distribution. Moreover, the effect of concrete damage due to earthquake loading on the performance of beam-column joints under service loading was investigated and a modified damage index was proposed to quantify the magnitude of damage in GFRP-RC beam-column joints under dynamic loading. Test results indicated that the geometrical configuration significantly affects the level of concrete damage and energy dissipation. Moreover, the level of residual damage in GFRP-RC beam-column joints after undergoing lateral displacements was related to reinforcement ratio of the main beams.

• Restorative Dentistry and Endodontics
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• v.29 no.5
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• pp.413-422
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• 2004

Established microleakage tests have their own disadvantages. In this study, 3D reconstruction method was tried to overcome these disadvantages. Four types of microleakage tests were used and relationships among them were estimated: penetrated dye volume: marginal adaptability: degree of dye penetration and relative penetrated length to cavity wall. Twenty-four Class V cavities were bulk filled with composite (Esthet X) following surface treatments: N group (no treatment): E group (etching only): T group (etching + Prime & Bond NT). 50% silver nitrate was used as a dye solution after thermocycling ($5^{\circ}C{\;}&{\;}55^{\circ}C$, 1.000 times). Teeth were serially ground with a thickness of 0.2 mm. Volume of dye penetration was estimated from a three-dimensionally reconstructed image with a software (3D-DOCTOR). Percentage of margin without gap was estimated from SEM and degree of dye penetration and the relative length of dye penetration to overall cavity wall were also estimated. ANOVA and Scheffe test for dye volume, Kruskal-Wallis and Mann-Whitney test for marginal quality, Spearman's rho test for checking of relationships among methods were used. The results were as follows: 1. Dye penetration could be seen from several directions, furthermore, its volumetric estimation was possible. 2. Reverse relationship was found between dye volume and marginal quality (r = -0.881/ p = 0.004). 3. Very low relationship was seen between dye volume and two-dimensional tests (degree of dye penetration and relative length). However, 2D evaluation methods showed high relationship (p = 0.002-0.054) each other. 4. Three times vertical section could be recommended as a 2D test.

• Journal of the Korean Association of Geographic Information Studies
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• v.3 no.2
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• pp.73-86
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• 2000

Using monthly AVHRR-NDVI composite images, global vector data and statistical information, land cover change patterns in Asia during the major growing season (June, July and August) were analyzed for each country. Specifically, explanations on NDVI changes were developed at a regional scale emphasizing human impacts on ground vegetation. The annual mean change in each country showed NDVI-gain trends in high latitude areas and some parts of eastern China and northern/western India. On the contrary, NDVI-loss trends were distinctive in Japan, Korea, some parts of southeastern China, Vietnam, Laos, Cambodia, Thailand, Myanmar and some parts in southwestern/eastern India. These patterns largely coincided with socio-economic information reflected by human behavior. The NDVI change trends showed significant correlation with forest area changes. Also, a multiple regression model showed that the NDVI change patterns were significantly dependent on the changes in forest area and total population.