• Journal of the Korean Arthroscopy Society
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• v.10 no.1
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• pp.45-52
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• 2006

Purpose: We evaluated the results of operative treatment of tibial plateau fractures using both arthroscopy and fluoroscopy. Materials and Methods: From May 1999 to February 2003, tibial plateau fractures were treated with arthroscopy. Tweenty seven patients are followed up over two years and the average follow-up period was fourty one months. We classified the fractures according to the Schatzker classification. We reduced the fracture over 2mm depression and displacement on articular surface in simple radiologic finding. Firstly, we treated the associated injuries and reduced the fractures using Steinmann pins. Then, we accomplished internal fixation or external fixation. Both the postoperative clinical and radiological results were evaluated by Rasmussen system. Results: In all tweenty seven cases, the fractures were healed completely in average fourty one months. According to Rasmussen classification, we obtained the excellent or good results in 23 cases. An average range of motion was between 2.5 degrees and 130 degrees. However, postoperative infection developed in one case and the other had loss of reduction. Conclusions: We consider that arthroscopically assisted operative treatment of tibial plateau fracture is a useful method. We can reduce joint surface correctly and treat associated injuries with arthroscopy. There are less complications.

• Journal of the Korea Concrete Institute
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• v.18 no.1 s.91
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• pp.83-90
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• 2006

This paper investigates experimentally the fire resistance performance and spatting resistance of high performance reinforced concrete column member subjected to fire containing polypropylene fiber(PP fiber) and cellulose fiber(CL fiber). An increase in PP fiber and CL fiber contents, respectively resulted in a reduction of fluidity due to fiber ball effect. Air content is constant with m increase in fiber content. Compressive strength reached beyond 50 MPa. Based on fire resistance test, severe failure occurred with control concrete specimen, which caused exposure of reinforcing bar. No spall occurred with specimen containing PP fiber. This is due to the discharge of internal vapour pressure. Use of CL fiber superior to control concrete in the side of spatting resistance, localized failure at comer of specimen was observed. Corner of specimen had deeper neutralization than surface of specimen. Specimen containing PP fiber had the least damaged area due to spatting. Neutralization depth ranged between 6 and 8 mm Residual compressive strength of specimen containing PP fiber maintained 40%, which is larger than control concrete with 20% of residual strength. Specimen containing CL fiber had 25% or residual strength.

• Journal of the Korea Concrete Institute
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• v.23 no.2
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• pp.145-150
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• 2011

Presently, mass concrete structures are being built in federal and private projects of civil infrastructures and building structures. The hydration heat of mass concrete structures is the most important factor in the quality of concrete matrix and construction period. Moreover, internal cracks caused by hydration heat degrades durability, water tightness, and strength of concrete. To reduce hydration heat, it is necessary to blend belite cement (${\beta}-C_2S$) with industrial by-products (i.e. granulated slag and fly ash). In this experiment, 14 levels of binary binders and 4 levels of ternary binders were used to understand the effect of different replacement ratio on hydration heat, strength and microstructure (i.e. SEM and XRD) of mortar. Cumulative hydration heat at 28 days for the binary and ternary binders was affected by replacement ratio of fly ash and/or granulated slag. As fly ash content increased, hydration heat decreased. As granulated slag content increased, reduction rate of the hydration heat was lower than when fly ash was used. Especially, the hydration heat of ternary binder blended with 40% flyash and 30% granulated slag showed about 50% of hydration heat from using belite cement (P). The study results showed that the temperature rise of concrete matrix can be decreased by using blended belite binders producing low hydration heat and reasonable strength.

• Korean Journal of Environmental Agriculture
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• v.18 no.2
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• pp.179-184
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• 1999

To examine the relationship between air pollution and occurrence of disease in plants, we investigated the alteration of physiology and biochemistry of Ginkgo biloba by inoculating with Coniothyrium sp. and fumigating with 0.1 ${\mu}l/l\;SO_{2-}$ Visual damage did not appear but photosynthesis, $CO_2$ use efficiency(CUE) and water use efficiency(WUE) were reduced when G. biloba was exposed to $SO_{2-}$for 7days (8 hours a day). When inoculated with Coniothyrium sp., the seventies of damage in G. biloba showed a threefold difference between $SO_{2-}$ treatment (SI) and $SO_{2-}$ free treatment (SFI) at day 42 from initial inoculation. Little difference was observed in sugar contents that may be used pathogens feed, among control, SFI and SI. In spite of the reduction in photosynthetic rate, sugar contents and CUE were maintained. WUE was enhanced 13% more at SI than SFI. The $CO_2$fixation boosted because of enhanced WUE, and thus sugar synthesis was not affected. In addition, sugar transport seems to be retarded for some internal alteration. Consequently, the severity of SI was more serious than that of SFI because Coniothyrium sp. easily invades into the physical texture of G. biloba weakened by $SO_2$ fumigation and because sugar was accumulated in leaves of G. biloba.

• Journal of the Korean Society of Hazard Mitigation
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• v.9 no.4
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• pp.11-20
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• 2009

By using the artificial lightweight aggregate for the natural aggregate depletes and destruction of environment and the application of lightweight concrete in structure, the lightweight concrete is manufactured. The fundamental characteristics by the waterbinder ratio was evaluated. It is suggested the method to control of pre-absorbed water of the lightweight aggregate. Lightweight concrete with pre-absorbed aggregate has similar characteristics compared to normal weight concrete regardless of water-binder ratio. According to the water-binder ratio, the drying condition, and the rebar, the unit mass of the lightweight concrete showed the reduction of 14.6${\sim}$21.0% as the range of 1,668${\sim}$1,998 $kg/m^3$ in comparison to the normal weight concrete. The lightweight aggregate pre-absorbed water showed the deferent evaporation quantity according to the water-binder ratio. As the water-binder ratio is lower, the oven dry vapour water is larger, therefore the internal curing water is increasing. In the same water-binder, comparing the normal concrete the lightweight concrete shows lower compressive strength which is due to the different strength of an aggregate. In the air dry curing, the normal weight concrete has a lower strength improvement effect in w/c 0.3 than the ratio 0.4 and 0.5. However, the strength improvement effect has increasing as the water-binder ratio was low in the light concrete.

• The Journal of the Korean bone and joint tumor society
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• v.17 no.2
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• pp.58-64
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• 2011

Purpose: The purpose of this study is to observe unicameral bone cyst (UBC) outcome after the fracture has healed and if there is any identifiable prognostic factors. Materials and Methods: 13 UBC patients with pathologic fracture from 2001 to 2010 were reviewed. The mean follow up were 26 months (3-90 months). There were 11 male and 2 female patients and the mean age of the patients were 10.2 years old (6-16 years). 9 involved proximal humerusand 2 involved humerus shaft and 1 involved proximal femur and 1 involved proximal tibia. The treatment of UBC fracture was conservative cast application to heal the fracture initially, and 1 patient was treated with primary auto bone graft and open reduction with internal fixation. 5 patients were treated with steroid injection during follow up period and 2 patients with auto bone graft. We analyzed the change of UBC during pathologic fracture healing period and prognostic factor about age, the size of UBC, the involvement of physis. Results: The mean duration of the fracture healing was 8.2 months. Complete healing were occurred at 4 patients (31%). No statiscal difference was checked with age about UBC healing (p=0.42). But, more larger size about UBC and more closer to physis, the healing was difficult (p=0.05, p=0.03). Conclusion: While pathologic fracture of UBC was possibly healed, active treatment should be applied especially those cysts that involvescloser area of the physis or large size.

• Journal of Korean Foot and Ankle Society
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• v.5 no.2
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• pp.112-119
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• 2001

Purpose: The purpose of this study is to analyze the clinical prognostic factors which may affect the postoperative clinical results of the unstable ankle fractures. Materials and Methods: This study is based on 62 unstable ankle fractures treated by open reduction and internal fixation from May 1994 to June 2000, with a minimum follow-up period of 12 months(range: 13 months-7 years 3 months). The 62 patients were average 39.1 years old with male: female ratio of 41:21. Based on Lauge-Hansen classification, the supination-external rotation type was the most common with 36 (58.1%) cases. The clinical results was assessed by American Orthopaedic Foot and Ankle Society(AOFAS) functional scale. The sex, age, body weight, trauma-operation interval, operation time, cause of injury, fracture type were statistically analyzed as the possible postoperative clinical prognostic factors. Results: Postoperative AOFAS functional scale was average 82.1 points with 22(35.5 %) cases excellent, 12(19.4%) good. 16(25.8%) fair and 12(19.4%) cases poor results. The age and the operation time were found to be statistically significant factors affecting the prognosis(p<0.001). The sex, weight, trauma-operation interval factors did not significantly affect the clinical results. The pronation-external rotation type showed better clinical tendency among the fracture types, but without the statistical significance. Conclusion: The surgically treated unstable ankle fractures in patients whose age was above 41 years old or operation time exceeding 90 minutes showed significantly poor clinical results.

• Journal of Korean Foot and Ankle Society
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• v.24 no.2
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• pp.81-86
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• 2020

Purpose: Ankle fractures with dislocations and pilon fractures at the distal tibia are usually associated with soft tissue damage caused by high-energy damage. Recently, a two-stage operation to perform internal fixation after the application of external fixation devices for stabilizing soft tissues has been accepted as the treatment of choice. This paper reports the clinical result of these injuries treated with threaded trans-calcaneal pin external fixation devices. Materials and Methods: Thirty-three patients diagnosed with ankle fractures with dislocations or tibial pilon fractures without open wounds. They underwent surgical treatment with threaded trans-calcaneal pin external fixation from January 2008 to February were enrolled in this study. This study evaluated the visual analogue scale (VAS), foot function index (FFI), and Olerud & Molander score as well as whether complications occurred. Results: The average VAS showed a meaningful decrease (p<0.001) from 7.4 before surgery to 2.6 after application of the external fixation device, and 1.4 at 12 months after surgery. The FFI also decreased significantly from 84.3 preoperatively to 20.3 at 12 months postoperatively (p<0.001). The Olerud & Molander score averaged 71.4 points, showing good clinical results. Complete bone union was observed in all patients. One patient each underwent debridement due to wound necrosis and infection in the pin insertion site. At the final follow-up, seven patients had posttraumatic ankle joint arthritis, according to a radiological examination. Conclusion: Manual reduction and external fixation using a threaded trans-calcaneal pin is a suitable surgical technique that is easy to perform and shows good clinical outcomes in stabilizing soft tissue damage in fractures and dislocations of ankle fracture or tibia pilon fractures in foot and ankle injury.

• Current Research on Agriculture and Life Sciences
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• v.32 no.1
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• pp.1-9
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• 2014

In contrast to conventional microwaves, QRD (Quadratic Residue Diffusor) microwaves are a new energy-efficient technology that enhances the effect of sterilization based on changing the wavelength phase difference. Therefore, this study investigated the sterilization of wood using environmentally friendly and low energy consuming QRD microwaves. The results are as follows: for the QRD microwaves used in this study, the efficiency E = 5.75e0.32 S ($R^2$=0.908). Although the early water content was not constant, the average water content was 30.3% and after one week of natural drying, the water content was 22.6%, representing an average water content reduction of about 8%. When increasing the microwave level from 3 kW ~ 9 kW, the time taken for the temperature to increase was reduced. After the QRD microwave treatment, the wood samples showed no change in their flexural rigidity, compressive strength, or cleavage. The QRD microwave levels used in the experiments were 3, 5, 7, and 9 kW, where 9 kW was found to be the most efficient. Thus, for the purpose of eliminating nematodes and termites inside wood, a higher QRD microwave level was found to be more effective and energy efficient.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.3
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• pp.112-118
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• 2018

In order to meet the strict emission regulations for internal combustion engines based on fossil fuel, the proportion of after-treatments for vehicles and vessels is gradually increasing. Diesel engines have high power, good fuel economy, and lower $CO_2$ emissions, and their market shares are increasing in commercial vehicles and passenger cars. However, NOx is generated in the localized high-temperature combustion regions, and particulate matter is formed in the zones of diffusion combustion. LNT and urea-SCR catalysts have been developed for after-treatment of the exhaust gas to reduce NOx in diesel vehicles. This study aims to improve the NOx reduction performance of Cu SCR catalyst, which is widely used in light, medium, and heavy-duty diesel engines. The de-NOx performance of $5Cu-2ZrO_2$/93Zeolyst(Si/Al=13.7) SCR catalyst was about 5-50% higher than that of $5Cu-2ZrO_2$/93Zeolite(Si/Al=2.9) at catalyst temperatures of $300^{\circ}C$ or higher. The zeolite had lower metal dispersion than zeolyst, and the reaction rate of the catalyst decreased as the average particle size increased. The $10Cu-2ZrO_2$/88Zeolyst catalyst loaded with 10wt% Cu had the highest NOx conversion rate of 40% at $200^{\circ}C$ and about 65% at $350^{\circ}C$. The ion exchange rate of Cu ions increased with that of Al, the crystalline compound of zeolite, and the de-NOx performance was improved by 20-40% compared to other catalysts.