• Wind and Structures
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• v.32 no.5
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• pp.471-485
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• 2021

Onshore wind turbines may experience substantially different wind loads depending on their working conditions, i.e. rotation velocity of rotor blades, incoming freestream wind velocity, pitch angle of rotor blades, and yaw angle of the wind-turbine tower. In the present study, aerodynamic loads acting on a horizontal axis wind turbine were accordingly quantified for the high tip speed ratio (TSR) at high yaw angles because these conditions have previously not been adequately addressed. This was analyzed experimentally on a small-scale wind-turbine model in a boundary layer wind tunnel. The wind-tunnel simulation of the neutrally stratified atmospheric boundary layer (ABL) developing above a flat terrain was generated using the Counihan approach. The ABL was simulated to achieve the conditions of a wind-turbine model operating in similar inflow conditions to those of a prototype wind turbine situated in the lower atmosphere, which is another important aspect of the present work. The ABL and wind-turbine simulation length scale factors were the same (S=300) in order to satisfy the Jensen similarity criterion. Aerodynamic loads experienced by the wind-turbine model subjected to the ABL simulation were studied based on the high frequency force balance (HFFB) measurements. Emphasis was put on the thrust force and the bending moment because these two load components have previously proven to be dominant compared to other load components. The results indicate several important findings. The loads were substantially higher for TSR=10 compared to TSR=5.6. In these conditions, a considerable load reduction was achieved by pitching the rotor blades. For the blade pitch angle at 90°, the loads were ten times lower than the loads of the rotating wind-turbine model. For the blade pitch angle at 12°, the loads were at 50% of the rotating wind-turbine model. The loads were reduced by up to 40% through the yawing of the wind-turbine model, which was observed both for the rotating and the parked wind-turbine model.

• Journal of Soil and Groundwater Environment
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• v.10 no.6
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• pp.63-67
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• 2005

Laboratory scale experiments were carried out to delineate the effects of liquid phases, such as soil water and light nonaqeous phase liquid (LNAPL) on the transport of gaseous ozone in unsaturated soil. Soil water enhanced the transport of ozone due to water film effect, which prevents direct reaction between soil particles and gaseous ozone, and increased water content reduced the breakthrough time of ozone because of increased average linear velocity and decreased air-water interface area. Diesel fuel as LNAPL also played a similar role with water film, so the breakthrough time of ozone in diesel-contaminated soil was significantly reduced compared with uncontaminated soil. Ozone breakthrough time was retarded with increased diesel concentration, however, because of high reactivity of diesel fuel with ozone. In unsaturated soil containing two liquids of soil water and LNAPL, the transport of ozone was mainly influenced by nonwetting fluid, diesel fuel in this study.

• Journal of the Korea Concrete Institute
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• v.26 no.5
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• pp.635-642
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• 2014

The weight of concrete could be reduced by using hollow core slabs instead of heavy solid slabs, leading to cost reduction. The long span be also achieved by introducing prestress in hollow core slabs. but the evaluation of shear strength of precast-prestressed hollow core slabs are needed because the cross section is reduced in web and arranging shear reinforcement is not possible. In this study, the shear strength of precast-prestressed hollow core slabs were evaluated based on experimental tests. For this purpose, six full scale specimens were made and tested. The shear strength of the specimens were compared with those evaluated from current design provision(EC2 ACI, EN1168 and AASHTO).

• Korean Journal of Cognitive Science
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• v.10 no.3
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• pp.17-28
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• 1999

Systematic distortions in perceived 3-D shape were obtained for elliptical and parabolic stereoscopic surfaces viewed at different distances under full and reduced cue conditions. In both conditions of Experiments 1 and 3, elliptical hemi-cylinders a appeared near veridical at the 45 cm viewing distances and flattened up to 74% of veridical at 135 cm. In Experiment 2, under full cue conditions, parabolic hemi-cylinders a appeared stretched to 118% of veridical at 45 cm, near veridical at 90 cm, and flattened to 85% of veridical at 135 cm. Under reduced cue conditions parabolas appeared flatter overall: veridical curvature was obtained at 45 cm viewing distance with flatness increasing to 68% of veridical at 135 cm. Results support a scaling explanation of perceived 3-D shape from disparity and rule out the alternative hypothesis that disparity curvature, an optical invariant, provides information for the direct perception of 3-D s shape.

• Journal of Korea Society of Industrial Information Systems
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• v.17 no.6
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• pp.51-58
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• 2012

Scirtothrips Dorsalis (Thysanoptera: Thripidae) recently has been recognized as a major source of the pest damage in the citrus fruit orchards. So its arrival has been predicted periodically but it is difficult to identify adults of the pest with the naked eyes because of their size smaller than the 0.8mm. In this paper, we propose a method to detect candidate areas for automatic identification of Scirtothrips Dorsalis on forecasting traps. The proposed method uses a histogram-based template matching where the composite image synthesized with the gray-scale image and the gradient image is used. In our experiments, images are acquired by the optical microscopy with 50 magnifications. To show the usefulness of the proposed method, it is compared with the method we previously suggested. Also, the performances when the proposed method is applied to noise-reduced images and gradient images are examined. The experimental results show that the proposed method is approximately 14.42% better than our previous method, 41.63% higher than the case that the noise-reduced image is used, and 21.17% higher than the case that the gradient image is used.

• Physical Therapy Rehabilitation Science
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• v.3 no.1
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• pp.1-6
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• 2014

Objective: Low level laser treatment (LLLT) is widely used in physical therapy practice. It is combined with physical therapy or LLLT alone. The purpose of this study is to evaluate the effectiveness of LLLT on patients' perception of general wrist pain. Design: Longitudinal study. Methods: Forty-eight subjects with wrist pain who were in the age range of 18-70 years old were examined. The subjects were asked, via an interview and a visual analog scale, to grade their wrist pain. They were asked to rotate their wrists through full range of motion and the angle at which any pain occurred was assessed. Each subject was then exposed to one of the following: 1) treatment with an infrared laser with the power turned off (placebo), 2) treatment with an infrared therapeutic laser, 3) treatment with a red therapeutic laser, 4) treatment with an ultraviolet laser, 5) treatment with a blue laser, 6) treatment with a Mickey Mouse flashlight. The duration of the treatment was 3 sessions in 3 days. Results: The results of the experiments showed that while pain was reduced both immediately after and the next day after laser therapy (p<0.05), there was no significant difference between the laser groups and the placebo group. However, the Mickey Mouse flashlight treatment groups had a greater range of motion than the laser groups (p<0.05). Conclusions: While pain was reduced in all laser groups, it was probably a placebo effect. The Mickey Mouse flashlight group probably received benefit from the heat of the flashlight.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.9
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• pp.670-676
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• 2011

Artificially metal-contaminated soils have been widely used for lab-scale soil washing and soil toxicity experiments. The artificial soil contamination methods consist of 1) first equilibrating soils with heavy metal solution, 2) filtrating or centrifuging soils from the mixture and 3) finally drying the soils. However, some of those artificially contaminated soil experiments have not clearly shown that the soils were thoroughly rinsed with water prior to conducting experiments. This study investigated the amount of heavy metal release from the artificially metal-contaminated soil by pre-water-rinsing. Three different artificially metal-contaminated soil preparation methods were first evaluated with Cd and Pb concentrations of soil. Then, this study investigated the effect of pre-water-rinsing on the Cd and Pb concentration of the artificially contaminated soil. Heavy metal concentrations of the soil produced by equilibrating and drying the metal solution-soil were significantly reduced by pre-water-rinsing. The results of the study implied that experimental results would be significantly distorted when the artificially heavy metal-contaminated soils were not thoroughly water-rinsed prior to conducting experiments. Therefore, the initial heavy metal concentration of the artificially contaminated soil should be determined after thoroughly rinsing the soil that was previously obtained through the adsorption and dry stages.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.54 no.1
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• pp.12-24
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• 2018

This study was conducted in order to improve opening efficiency of the miniaturized large-scale net for anchovy boat seine gear to reduce the fleet size. Field experiments were performed to observe geometry of nets by catcher boats. When the distances between the two ships were 150, 300 and 450 m, and the speeds of towing nets were 0.6, 0.9, and 1.2 k't, respectively. The vertical opening and actual opening of each part of the miniaturized large-scale net was as follows: the front part of the wing net, 8.7-13.3 m, 51-78%; the middle part of the wing net, 28.1-34.2 m, 55-67%; the entrance of the inside wing net, 31.3-38.5 m, 60-73%; the square and bosom, 22.7-29.6 m, 47-62%; the entrance of the body net, 20.9-26.4 m, 42-52%; the entrance of the bag net, 17.2-21 m, 72-89%; the flapper, 13.2-15.3 m, 78-83%; and the end of the bag net, 13.2-15.7 m, 72-75%. By connecting the net pendants with the front part of the wing net, the opening of the front part of the wing net was significantly improved compared to the traditional gear, which ensured both the wing net and the inside wing net with a normal net height. This, in turn, increased the efficiency of herding. The height of the body and bag nets was also higher than that of the tradition gear. In particular, the body net attached to the gear significantly improved the pocket shape of the gear and reduced the number of fish that were caught and escaped from the bag net, which increased the rate of fishing. The tension of towing nets was measured approximately between 2,958 and 7,110 kg, which indicates that the fleet can tow nets with 350 ps, the standard engine horse power. The fishing operation time was shortened compared with of the existent net, and the large-scale buoy attachment operation was also possible to operate the ship without fish detecting boat.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.50 no.4
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• pp.238-246
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• 2005

Rice yield and protein content have been shown to be highly variable across paddy fields. In order to characterize this spatial variability of rice within a field, two-year experiments were conducted in 2002 and 2003 in a large-scale rice field of $6,600m^2$ In year 2004, an experiment was conducted to know if variable rate treatment (VRT) of N fertilizer, that was prescribed for site-specific management at panicle initiation stage, could reduce spatial variation in yield and protein content of rice while increasing yield compared to conventional uniform N topdressing (UN, 33kg N/ha at PIS) method. VRT nitrogen prescription for each grid was calculated based on the nitrogen (N) uptake (from panicle initiation to harvest) required for target rice protein content of $6.8\%$, natural soil N supply, and recovery of top-dressed N fertilizer. The required N uptake for target rice protein content was calculated from the equations to predict rice yield and protein content from plant growth parameters at panicle initiation stage (PIS) and N uptake from PIS to harvest. This model· equations were developed from the data obtained from the previous two-year experiments. The plant growth parameters for the calculation of the required N were predicted non-destructively by canopy reflectance measurement. Soil N supply for each grid was obtained from the experiment of year 2003, and N recovery was assumed to be $60\%$ according to the previous reports. The prescribed VRT N ranged from 0 to 110kg N/ha with an average of 57kg/ha that was higher than 33 kg/ha of UN. The results showed that VRT application successfully worked not only to reduce spatial variability of rice yield and protein content but also to increase rough rice yield by 960kg/ha. The coefficient of variation (CV) for rice yield and protein content was reduced significantly to $8.1\%$ and $7.1\%$ in VRT from $14.6\%$ and $13.0\%$ in UN, respectively. And also the average protein content of milled rice in VRT showed very similar value of target protein content of $6.8\%$. In conclusion the procedure used in this paper was believed to be reliable and promising method for reducing within-field spatial variability of rice yield and protein content. However, inexpensive, reliable, and fast estimation methods of natural N supply and plant growth and nutrition status should be prepared before this method could be practically used for site-specific crop management in large-scale rice field.

• Proceedings of the Korean Society of Crop Science Conference
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• 2005.08a
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• pp.57-74
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• 2005

Rice yield and protein content have been shown to be highly variable across paddy fields. In order to characterize this spatial variability of rice within a field, the two-year experiments were conducted in 2002 and 2003 in a large-scale rice field of $6,600m^2$ In year 2004, an experiment was conducted to know if prescribed N for site-specific fertilizer management at panicle initiation stage (VRT) could reduce spatial variation in yield and protein content of rice while increasing yield compared to conventional uniform N topdressing (UN, ,33 kg N/ha at PIS) method. The trial field was subdivided into two parts and each part was subjected to UN and VRT treatment. Each part was schematically divided in $10\times10m$ grids for growth and yield measurement or VRT treatment. VRT nitrogen prescription for each grid was calculated based on the nitrogen (N) uptake (from panicle initiation to harvest) required for target rice protein content of $6.8\%$, natural soil N supply, and recovery of top-dressed N fertilizer. The required N uptake for target rice protein content was calculated from the equations to predict rice yield and protein content from plant growth parameters at panicle initiation stage (PIS) and N uptake from PIS to harvest. This model equations were developed from the data obtained from the previous two-year experiments. The plant growth parameters for this calculation were predicted non-destructively by canopy reflectance measurement. Soil N supply for each grid was obtained from the experiment of year 2003, and N recovery was assumed to be $60\%$ according to the previous reports. The prescribed VRT N ranged from 0 to 110kg N/ha with average of 57kg/ha that was higher than 33kg/ha of UN. The results showed that VRT application successfully worked not only to reduce spatial variability of rice yield and protein content but also to increase rough rice yield by 960kg/ha. The coefficient of variation (CV) for rice yield and protein content was reduced significantly to $8.1\%\;and\;7.1\%$ in VRT from $14.6\%\;and\;13.0\%$ in UN, respectively. And also the average protein content of milled rice in VRT showed very similar value of target protein content of $6.8\%$. Although N use efficiency of VRT compared to UN was not quantified due to lack of no N control treatment, the procedure used in this paper for VRT estimation was believed to be reliable and promising method for managing within-field spatial variability of yield and protein content. The method should be received further study before it could be practically used for site-specific crop management in large-scale rice field.