• Journal of the Korean Wood Science and Technology
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• v.42 no.4
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• pp.483-490
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• 2014

The effect of microfibrillated cellulose (MFC) content and coupling agent (polymeric methylene diphenyl diisocyanate, pMDI) on the properties of MFC-reinforced polybutylene succinate (PBS) nanocomposite. With increasing MFC content, tensile strength and elastic modulus were increased. More than 1.5 times in tensile strength of PBS/MFC(70/30) nanocomposite was improved by the addition of pMDI (1 phr), compared to the nanocomposite without pMDI. This trend was being significant in nanocomposite with higher MFC content. Thermal stability of the nanocomposite was increased by the addition of pMDI. These improvements is considered to be due to the improvement of MFC dispersion and interfacial adhesion between MFC and PBS matrix.

• Journal of the Korean Wood Science and Technology
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• v.38 no.6
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• pp.541-546
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• 2010

This study was to investigate the dry bond strengths of the plywoods manufactured with 3 hours ozonized soybean oil (SBO)/polymeric methylene diphenyl diisocyanate (pMDI) adhesive at mid and high curing temperature. In results of the dry bonding strengths of the 3 hrs-ozonized SBO mixed with pMDI at high curing temperature were respectively the strengths of weight ratio of 3hrs-ozonized SBO : pMDI, 1 : 0.5, 4.74 kgf/$cm^2$, 1 : 0.75, 7.14 kgf/$cm^2$ 1 : 1, 9.29 kgf/$cm^2$, 1 : 2, 16.53 kgf/$cm^2$, 1 : 3, 17.42 kgf/$cm^2$, and 1 : 4, 16.75 kgf/$cm^2$. Therefore, it was found that the equivalent ratio was formed approximately between 3 hrs-ozonized SBO : pMDI 1 : 2 and 1 : 3. The dry bonding strengths of the 3hrs-ozonized SBO mixed with pMDI at medium curing temperature were respectively the strengths of weight ratio of 3 hrs-ozonized SBO : pMDI, 1 : 0.5, 3.16 kgf/$cm^2$, 1 : 0.75, 6.13 kgf/$cm^2$ 1 : 1, 8.18 kgf/$cm^2$, 1 : 2, 11.82 kgf/$cm^2$. In this experiment the higher bonding strength at high curing temperature was shown approximately between 3 hrs-ozonized SBO : pMDI 1 : 2 and 1 : 3. If this wood adhesive is used at high curing temperature, it is possibile to bond the plywoods.

• Journal of the Korean Wood Science and Technology
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• v.47 no.2
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• pp.200-209
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• 2019

To improve the water resistance of melamine-urea-formaldehyde (MUF) resins, different levels of blocked polymeric 4,4 diphenyl methane diisocyanate (B-pMDI) were blended with MUF resins to prepare B-pMDI/MUF hybrid adhesives, and their adhesion performances were evaluated for the surface lamination of fancy veneer on plywood. FT-IR spectra showed that the de-blocked -NCO groups reacted with the -OH of hydroxymethyl groups of the MUF resins to form urethane bonds at 2% B-pMDI/MUF, which was detected before and after their hydrolysis. The mass loss after the hydrolysis consistently decreased as the B-pMDI level increased, indicating an improvement in the water resistance. As the B-pMDI level increased, the activation energy of hybrid adhesives decreased, which improved the reactivity of the hybrid adhesives. Additionally, the water resistance improvement of the hybrid adhesives increased the tensile shear strength of the surface laminated plywood in semi-water proof and water-proof by 23 % and 8 %, respectively, at 2% B-pMDI level. This was likely due to the urethane linkages in the hybrid adhesives. However, the formaldehyde emission from plywood panels bonded with the hybrid adhesives increased in the dry state, indicating incomplete curing of the hybrid adhesives.

• Journal of the Korean Wood Science and Technology
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• v.37 no.1
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• pp.56-64
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• 2009

The purpose of this study was to investigate and develop an eco-friendly wood adhesive based on vegetable oil (especially soybean oil), the renewable and sustainable natural resources, using ozonification technology for the chemical structure modification. The soybean oil (SBO) was reacted with $O_3$ at the rate of 7.13 g/h for different times, 15 minutes, 30 minutes, 60 minutes, and 120 minutes. The investigation of the modified chemical structure of the ozonized SBOs were conducted using FT-IR, $^1H$-NMR, MALDI-TOF MS, and GC/MS. As ozonification time increased, the peak of the unsaturated double bonds was disappeared and aldehyde or carboxyl peak appeared because ozonification broke the oil into small molecules. The plywoods were made at $110^{\circ}C$ with 30 seconds/mm hot-press time using the different ozonized SBO/pMDI adhesives and were tested for the dry, wet, cyclic boil test according to the Korea Industrial Standard F3101 Ordinary plywood. The bond strengths gradually increased with increasing ozonification time. The weight ratio 1:1 (ozonized SBO/pMDI), all strengths in 15, 30 and 60 minuets, exceeded constantly the dry, wet, cyclic boiling standard requirement. The range of ozonification time and weight ratio can fulfil1 the requirment of the wet test standard were 30~60 minutes and more than 0.5 pMDI. From the comprehensive view on the results of above experiments, it could be confirmed through experiments that ozonized SBO/pMDI has characteristics of effective reactivity and wet stability showed as an excellent candidate of wood adhesive applications.

• Journal of the Korean Wood Science and Technology
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• v.34 no.6
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• pp.29-35
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• 2006

This stud y was conducted to investigate the bonding strength of plywood bonded with fatty acid-glycerol-pMDI adhesives with equivalent ratios of 1:1:2, 1:1:3, 1:1:4, 1:1:5, and 1:1:6. With veneer moisture contents of 0%, 3%, 5%, 8% and 15%, the bonding strengths exceeded the requirement of Korean plywood standard of $7.0kgf/cm^2$ with values of $13.7kgf/cm^2$, $11.6kgf/cm^2$, $11.2kgf/cm^2$, $9.8kgf/cm^2$, and $7.4kgf/cm^2$, respectively at fatty acid-glycerol-pMDI ratio of 1:1:2. With veneer moisture content of 30%, the bonding strengths exceeded th e requirement of Korean plywood standard of $7.0kgf/cm^2$, when fatty acid-glycerol-pMDI ratios were 1:6. Finally for satisfying the Korean plywood standard, the ratio of MDI in fatty acid-glycerol-pMDI should be increased with increasing of veneer moisture content.

• Journal of the Korean Wood Science and Technology
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• v.38 no.5
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• pp.414-420
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• 2010

The effect of polymeric diphenyl methane-4,4-diisocyanate (pMDI) or 1,6-hexamethylene diisocyanate (HDI) in the UMF resin was discussed for improvement of the dry and wet shear strengths of plywood manufactured from high moisture content veneers. The curing behavior of UMF resin by pMDI or HDI content was examined by DSC and TGA, and its adhesion performance was evaluated by dry and wet shear strength tests of plywood. With the increase of pMDI content in the UMF resin, the curing temperature, reaction enthalpy (${\Delta}H$), and thermal stability consistently increased. With the increase of HDI content in the UMF resin, however, the curing temperature and reaction enthalpy (${\Delta}H$) decreased consistently and the thermal stability slightly increased in the range of 200 to $400^{\circ}C$ but decreased beyond $400^{\circ}C$. Also, the dry tensile shear strength increased up to the pMDI content of 5% and then decreased with its further addition but the wet tensile shear strength showed slight tendency to increase with the increase of pMDI content in the UMF resin. As the HDI content increased, however, the dry and wet tensile shear strengths of plywood consistently increased.

• Journal of the Korean Wood Science and Technology
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• v.39 no.6
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• pp.498-504
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• 2011

The purpose of this study was to investigate and develop an eco-frendly wood adhesive based on vegetable oil (especially soybean oil), the renewable and sustainable natural resources, using ozonification technology for the chemical structure modification. The waste soybean oil (WSBO) was reacted with $O_3$ at the rate of $450m{\ell}$(acetone) : $50m{\ell}$ (WSBO) for different times, 1, 2, 3 hrs. The investigation of the modified chemical strecture of the ozonied WSBOs were conducted using FT-IR. As ozonification time increased, the peak of the unsaturated double bonds was disappeared especially ozonized-3hrs and aldehyde or carboxyl peak appeared because ozonification broke the oil into small molecules. The plywood were made at $150^{\circ}C$ with 4 minutes hot-press time using the different ozonized 3 hrs WSBO/pMDI adhesives and were tested for the dry, wet, cyclic boil test according to the Korea Industrial Standard F3101 Ordinary plywood. The bond strengths gradually increased until 1 : 0.5~1 : 3, but it decreased 1 : 4, as the contents of pMDI increased. The results of the dry, wet and cyclic bond strengths the equivalent ratio was formed approximately between 1 : 2~1 : 3. And the 1 : 1~1 : 4 strengths met constantly the standard requirement of 7.0kgf/$cm^2$ (KS F3101). From the comprehensive view on the results of above experiment, it could be confirmed that ozonized WSBO/pMDI has characteristics of effective reactivity and wet stability showed as an excellent candidate of wood adhesive applications.

• Korean Journal of Radiology
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• v.20 no.6
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• pp.931-938
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• 2019

Objective: To compare inferior capsular redundancy by using magnetic resonance arthrography (MRA) images in patients with multidirectional instability (MDI) of the shoulder and control subjects without instability and thereby develop a screening method to identify the presence of shoulder MDI. Materials and Methods: The MRA images of patients with MDI of the shoulder (n = 65, 57 men, 8 women; mean age, 24.5 years; age range, 18-42 years) treated over an eight-year period were retrospectively reviewed; a control group (n = 65, 57 men, 8 women; mean age, 27.4 years; age range, 18-45 years) without instability was also selected. The inferior capsular redundancy was measured using a new method we named the glenocapsular (GC) ratio method. MRA images of both groups were randomly mixed together, and two orthopedic surgeon reviewers measured the cross-sectional areas (CSAs) and sagittal capsule-head ratios on oblique sagittal images, as well as the axial capsule-head ratios on axial images and GC ratios on oblique coronal images. Results: The CSAs and GC ratios were significantly higher in patients than in controls (both, p < 0.001); however, the sagittal capsule-head ratios and axial capsule-head ratios were not significantly different (p = 0.317, p = 0.053, respectively). In addition, GC ratios determined the presence of MDI more sensitively and specifically than did CSAs. A GC ratio of > 1.42 was found to be most suggestive of MDI of the shoulder, owing to its high sensitivity (92.3%) and specificity (89.2%). Conclusion: GC ratio can be easily measured and used to accurately screen for MDI of the shoulder.

• Journal of the Korean Applied Science and Technology
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• v.32 no.4
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• pp.607-615
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• 2015

To investigate the adhesion effect of various kinds and contents of polymeric methylene diphenyl diisocyanates (pMDIs) on adhesion performance, wood adhesives (A-1~5) were synthesized and characterized. As results, when the amount of pMDI increased in adhesives, the dry tensile strength was found to be proportionally increased sustaining at around $16.0{\sim}21.6kgf/cm^2$. The polyurethane (PU) resin, which used M11S as a source of pMDI showed the best wet tensile strength at $11.9kgf/cm^2$ and cyclic boil tensile strength at $8.1kgf/cm^2$, which satisfied the requirement of over $7kgf/cm^2$. Thermal properties of the rice powder (RP) based polyurethane resins were characterized by differential scanning calorimetry (DSC) and Thermal gravimetric analysis (TGA). Thermal stability of polyurethane resins increased to $250^{\circ}C$ with adding pMDIs. The more pMDI (M5S) was added to adhesive, the higher thermal stability of the resin was observed by TGA.

• Clinical and Experimental Pediatrics
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• v.52 no.11
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• pp.1221-1227
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• 2009

Purpose:To identify the risk factors for poor neurodevelopmental outcomes in high-risk neonates. Methods:We studied 94 infants admitted to the neonatal intensive care unit at the Sanggye Paik Hospital between January 2002 and November 2005 and evaluated the follow-up data. The following events were considered as risk factors: ${\leq}32$ weeks of gestation, very low birth weight, Apgar scores of less than 5, neonatal resuscitation, neonatal seizure, congenital infection, and abnormalities in cranial ultrasound or magnetic resonance imaging (MRI). The infants who had any one of these risk factors were included. They were evaluated at their mean corrected age of 13.84${\pm}$8.03 months. Mental and Psychomotor Developmental Indices (MDI, PDI) were determined by a clinical psychologist using the Bayley Scales of Infant Development II. Results:The mean MDI and PDI of all the patients were 96.28${\pm}$26.70 and 94.00${\pm}$22.80, respectively. Abnormalities on cranial ultrasound or MRI were significant predictors of both low MDI (P<0.05) and low PDI (P<0.001). These abnormalities showed a stronger association with low PDI than with low MDI. The infants with periventricular leukomalacia had the lowest MDI and PDI ($70.10{\pm}28.68$ and $69.70{\pm}24.91$, respectively). Apgar score at 1 minute and very low birth weight were also significant predictors for low PDI (P<0.05, P<0.05, respectively). Conclusion:Image findings with cranial ultrasound or MRI were the strongest predictors of neurodevelopmental outcome. Periventricular leukomalacia was the best predictive factor for mental and psychomotor development.