• Asian Journal of Turfgrass Science
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• v.21 no.2
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• pp.127-135
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• 2007

Korea and Japan hosted the FIFA World Cup Soccer Game in 2002. Ten stadiums had been built and more than 30 soccer grounds for practice were renovated in Korea. Sport fields in both countries had problems on cool-season turfgrass growth and quality by summer decline during humid and warm climate especially followed by intensive uses. We measured the effects of air-flow system, which is designed to optimize rootzone soil gas and moisture levels to promote the growth and maintenance turfgrass. This experiment was carried out to verify the effects of the system on soil gas exchange, ground resilience, and turfgrass recovery in turfgrass rootzone. Within 1 or 2hr of operation of the system, rootzone soil gas ($CO_2$, $O_2$) levels returned to natural atmospheric levels completely Soil $CO_2$ levels began to decrease within the first 10 min of operation of the system. The levels were reduced from 1.3 to 0.06% after 30 min, and natural atmospheric levels within 1 hr. When the system was turned off, $CO_2$ levels increased to 0.36% and 0.7% after 5 and 20 hr, respectively. The application of the system did not affect the resilience of turf surface after traffic treatments. Higher traffic treatment resulted in higher surface resilience especially in zoysiagrass plots. Operation of the system had a significant beneficial impact on turf recovery by increased root dry wight and improved turf quality, as compared with the non-operated check plots.

• Journal of the Korean Society of Industry Convergence
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• v.23 no.6_2
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• pp.1033-1042
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• 2020

Shale shaker which is one of the mud circulation systems is composed of a basket, a vibrator and a screen. Its purpose of a shale shaker is to induce drilling fluid to flow through a screen, transport solids across a screen surface, and discharge solids off the end of the screen. The new shale shaker for the on-shore drilling system is designed to be smaller than the original shale shaker which has the same capacity with the new on to enable to transport and to operate on the trailer. In this study, structural and vibrational analysis of shale shaker was carried out to evaluate the appropriateness of the design in terms of the structural stability.

• Macromolecular Research
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• v.8 no.4
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• pp.179-185
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• 2000

Generally vascular grafts with a relatively large inner diameter (> 5 mm) have been successfully employed for replacement in the human body. However, the use of small diameter grafts is limited, because these grafts rapidly occlude due to the thrombosis. The ideal blood-contacting surface of a prosthesis would be an endothelial cell (EC) lining, because the confluent monolayer of healthy ECs that culture natural blood vessels represents the ideal nonthrombogenic surface. For vascular graft application, the stable EC adhesion on surface under How conditions is very important. In this study, the adhesive strength of ECs attached on polymer surfaces coated with collagen type IV (Col IV), fibronectin (Fn), laminin (Ln), and treated with corona was investigated onto polyurethane (PU) films. The EC-attached PU surfaces were mounted on parallel-plate flow chambers in a How system prepared for cell adhesiveness test. Three different shear stresses (100, 150, and 200 dyne/㎠) were applied to the How chambers and each shear stress was maintained for 120 min to investigate the effect of shear stress and surface treatment condition on the EC adhesion strength. It was observed that the EC adhesion strength on the surface-modified PU films was in the order of Ln≡Fn > Col IV > corona 》 control. More than 70% of the adhered cells were remained on surface-modified PU surface after applying the shear stress,200 dyne/㎠ for 2 hrs, whereas the cells were completely detached on the control PU surface within 10 min after applying the same shear stress. It seems that the type of adsorbed proteins and hydrophilicitv onto the PU surfaces play very important roles for cell adhesion strength.

• The Journal of Korean Academy of Prosthodontics
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• v.45 no.4
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• pp.457-468
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• 2007

Statements of problem: The fracture of acrylic resin dentures remains an unsolved problem. Therefore, many investigations have been performed and various approaches to strengthening acrylic resin, for example, the reinforcement of heat-cured acrylic resin using glass fibers, have been suggested over the years. Silane is important for bonding between glass fiber and resin. Purpose: The aim of the present study was to investigate the effect of various silane on the strength of PMMA resin and roughness of resin-glass fiber complex after abrasion test. Material and methods: 3mm glass fiber (Chopped strand, Hankuk fiber Co., Milyang, Korea) was treated with 3 kinds of silane (MPS, EPS, APS) (Sila-ace, Chisso chemical, Tokyo, Japan) and mixed with PMMA resin(Vertex RS, Vertex Dental B.V., Zeist, Netherlands). Transverse strength and Young's modulus was measured using Instron (Instron model 4466, Instron, Massachusetts, USA). After abrasion test (The 858 Mini Bionix II Test System, MTS System Co., Minnesota, USA) surface roughness was evaluated using tester (Form Talysurf plus, Taylor Hopson Ltd., Leicester England). Examination of scanning electron microscope was also performed. Results: Within this study, the following conclusions were drawn. 1. Surface treatment of glass fiber with MPS and APS increased transverse strength of PMMA resin complex, but surface treatment with EPS decreased transverse strength of PMMA resin complex (p<0.05). 2. Silane treated glass fiber increased Young's modulus of PMMA resin complex compared to desized glass fiber (p<0.05). 3. Roughness increased after abrasion test in case of PMMA resin reinforced with desized glass fiber (p<0.05). 4. Roughness change was not observed after abrasion test in case of PMMA resin reinforced with silane treated glass fiber (p>0.05).

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.291-293
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• 2002

Accurate dose calculation in radiation treatment planning is most important for successful treatment. Since human body is composed of various materials and not an ideal shape, it is not easy to calculate the accurate effective dose in the patients. Many methods have been proposed to solve the inhomogeneity and surface contour problems. Monte Carlo simulations are regarded as the most accurate method, but it is not appropriate for routine planning because it takes so much time. Pencil beam kernel based convolution/superposition methods were also proposed to correct those effects. Nowadays, many commercial treatment planning systems, including Pinnacle and Helax-TMS, have adopted this algorithm as a dose calculation engine. The purpose of this study is to verify the accuracy of the dose calculated from pencil beam kernel based treatment planning system Helax-TMS comparing to Monte Carlo simulations and measurements especially in inhomogeneous region. Home-made inhomogeneous phantom, Helax-TMS ver. 6.0 and Monte Carlo code BEAMnrc and DOSXYZnrc were used in this study. Dose calculation results from TPS and Monte Carlo simulation were verified by measurements. In homogeneous media, the accuracy was acceptable but in inhomogeneous media, the errors were more significant.

• The Journal of Korean Physical Therapy
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• v.21 no.3
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• pp.17-24
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• 2009

Purpose: The purpose of this study was to investigate the effects of a combination of isotonic (CI) technique on the balance, muscle fatigue and muscle activities of the quadriceps muscle in the paretic leg of hemiplegic patients. Method: All the subjects received a combined isotonic technique of proprioceptive neuromuscular facilitation (PNF) for about 30 minutes 3 times per week for 6 weeks. The root mean square (RMS) and mid frequency (MF) were recorded by surface electromyography (EMG)(EMG/EP system, OXFORD Medelec, UK) during maximal voluntary isometric contractions (MVIC). The balance ability was measured by a balance system (BIODEX, USA). Result: The RMS of the quadriceps muscle at post-treatment was significantly increased compared to that at pretreatment (p<0.05). Yet there was no significant difference among the three muscles. There were no significant difference in the MF of the vastus lateralis and rectus femoris between pre- and post-treatment, but the MF of the vastus medialis was significantly decreased (p<0.05). There was a significant difference in the vastus medialis and lateralis between pre- and post-treatment (p<0.05). Moreover, the overall stability index at post-treatment was significantly decreased compared to that at pre-treatment (p<0.05). But there was no significant difference between the anterior/posterior and medial/lateral stability indexes. Conclusion: The results of this study indicated that a CI technique of PNF had an effect to improve the balance and muscle activity in hemiplegic patients.

• Journal of the Korean Applied Science and Technology
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• v.30 no.1
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• pp.166-172
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• 2013

The purpose of this study is to evaluate the treatment ability of refractory organics in hot rolling precess waste water by redox(reduction and oxidation) reaction. Metal is oxidized in an aqueous solution to generate electron which can reduce water to generate hydroxy radical. These hydroxy radical is very effective to conduct hydrogen abstraction reaction and addition reaction to the carbon - carbon unsaturated link. The surface area of metal alloy reaction material is more than enough to get equilibrium at a single treatment. The efficiency of COD treatment by redox reaction showed maximum at mild pH of pH 7 and pH 6. But it was not effective in acidic atmosphere of pH 3, 4, 5 and basic atmosphere of pH 8 or over. Redox reaction system in much more helpful in a commercial coagulation sedimentation treatment than exclusive system.

• Journal of the Korean Society of Industry Convergence
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• v.21 no.5
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• pp.227-234
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• 2018

The smart irrigation system using ICT technology is crucial for stable production of upland crops. The objective of this study was to develop a smart irrigation system that can control soil water, depending on irrigation methods, in order to improve crop production. In surface irrigation, three irrigation methods (sprinkler irrigation (SI), surface drip irrigation (SDI), and fountain irrigation (FI)) were installed on a crop field. The soil water contents were measured at 10, 20, 30, and 40 cm depth, and an automatic irrigation system controls a valve to maintain the soil water content at 10 cm to be 30%. In subsurface drip irrigation (SSDI), the drip lines were installed at a depth of 20 cm. Controlled drainage system (CDS) was managed with two ground water level (30 cm and 60 cm). The seasonal irrigation amounts were 96.4 ton/10a (SDI), 119.5 ton/10a (FI), and 113 ton/10a (SI), respectively. Since SDI system supplied water near the root zone of plants, the water was saved by 23.9% and 17.3%, compared with FI and SI, respectively. In SSDI, the mean soil water content was 38.8%, which was 10.8% higher than the value at the control treatment. In CDS, the water contents were greatly affected by the ground water level; the water contents at the surface zone with 30 cm ground water level was 9.4% higher than the values with 60 cm ground water level. In conclusion, this smart irrigation system can reduce production costs of upland crops.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.2
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• pp.126-135
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• 2015

Increase of delivery effect of pollutant loads and surface runoff due to urbanization of catchment area results in serious environmental problems in receiving urban streams. This study aims to develop integrated stormwater management system to assist efficient urban stream flow and water quality control using information from the Storm Water Management Model (SWMM), real time water level and quality monitoring system and remote or automatic treatment facility control system. Based on field observations in the study site, most of the pollutant loads are flushed within 4 hours of the rainfall event. SWMM simulation results indicates that the treatment system can store up to 6 mm of cumulative rainfall in the study catchment area, and this means any type of normal rainfall situation can be treated using the system. Relationship between rainfall amount and fill time were developed for various rainfall duration for operation of stormwater treatment system in this study. This study can further provide inputs of river water quality model and thus can effectively assist integrated water resources management in urban catchment and streams.

• Journal of Korean Society on Water Environment
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• v.28 no.1
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• pp.94-101
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• 2012

The performance data for eight years from a free-surface-flow constructed wetland system receiving agricultural tailwater were used to analyze denitrification rate and nitrogen treatment characteristics according to season and wetland design. Seasonal difference between growing season (March~November) and winter season (December~February) was shown in the concentration of all nitrogen species. Seasonal nitrogen treatment has similar trend with temperature and measured denitrification rate. The highest denitrification rate was measured in July, but treatment efficiency was most higher in May and June. Nitrogen absorption of vegetation could affect to these wetland performances, therefore dense population of wetland vegetation might be helpful. According to design of wetland, at least 25~50 m of wetland length was needed to decrease effluent T-N concentration to background concentration in growing season. In winter season, wetland needed much longer distance to reduce T-N concentration. Mass removal rate was continuously high through whole year because runoff coefficient was low in winter season. Applicability of constructed wetland was observed for the total maximum daily load that control T-N load.