• Journal of the Korean Wood Science and Technology
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• v.45 no.3
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• pp.360-367
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• 2017

This study was carried out to compare the characteristics of low density fiberboards (LDFs) manufactured with different adhesive types such as melamine urea formaldehyde (MUF), phenol formalehyde (PF), emulsified MDI (eMDI) and latexes resins. As results, hard LDFs were successfully manufactured by MUF, PF and eMDI resins. Thermal conductivities of all LDFs were significantly lower than commercial medium density fiberboard. Especially, all LDFs showed comparable thermal insulation performance with extruded polystyrene foam (XPS). LDF manufactured with eMDI resins showed the highest physical properties such as thickness/length swelling by water absorption and bending strength.

• Journal of the Korean Wood Science and Technology
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• v.45 no.5
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• pp.580-587
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• 2017

Woodfiber insulation board can be considered as a one of the key material for low energy consumption, comfortable and safety construction of residential space because of its eco-friendly and high thermal insulation performance. This study was carried out to investigate the formaldehyde (HCHO) total volatile organic compounds (TVOC) emission properties and combustion shapes by flame test of low density fiberboards (LDFs) prepared with different adhesives. HCHO TVOC emission and combustion properties of LDFs prepared by melamine urea formaldehyde (MUF), phenol formaldehyde (PF), emulsified methylene diphenyl diisocyanate (eMDI) and latex resin adhesives were measured by desiccator method, 20 L chamber method, and flame test, respectively. As results, LDFs manufactured by MUF, eMDI and latex resin adhesives satisfied the Super $E_0$ grade of HCHO emission performance except PF resin. Furthermore, TVOC emission of all LDFs were satisfied the Korean indoor air quality standard (below $400{\mu}g/m^2{\cdot}h$). Especially, LDF with eMDI resin adhesive showed the lowest HCHO and TVOC emissivity, that $0.14mg/{\ell}$, $12{\mu}g/m^2{\cdot}h$, respectively. However, eMDI emitted the small amount ($3{\mu}g/m^2{\cdot}h$) of toluene in VOC components. In the flame test, LDF with MUF resin adhesives showed the most favorable shape after flame test compare to LDFs prepared other adhesives. Based on HCHO and TVOC emission, and combustion shapes, MUF resin adhesive may be recommended to prepare LDF for insulation purpose.

• 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.

• Transactions on Electrical and Electronic Materials
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• v.18 no.4
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• pp.211-216
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• 2017

The dielectric properties of two polyurethanes (PUs) with different hard segments, i.e., aromatic methylene di-p-phenyl diisocyanate (MDI) and aliphatic hexamethylene diisocyanate (HDI), were investigated in the temperature range of -100 to $100^{\circ}C$ and in the frequency range of 1 Hz to 3 kHz. The ${\alpha}$-relaxations induced by the glass transition of the equivalent soft segments in the two PUs occurred at relaxation times of ${\tau}=3.46{\times}10^{-3}s$ for MDI-PU and ${\tau}=3.39{\times}10^{-2}s$ for HDI-PU at $-20^{\circ}C$, in accord with the temperature-frequency superposition principle, resulting in similar shifting factors. However, different I-relaxations were observed for the two PUs. The I-relaxation of MDI-PU occurred due to the mobility of the chain extenders near $80^{\circ}C$ with a slower shifting rate than the ${\alpha}$-relaxation. On the other hand, I-relaxation arising from both the extender and the unconstrained hard segments of HDI-PU occurred at $70{\sim}100^{\circ}C$, indicating complicated dielectric behavior due to partial interaction with the ${\alpha}$-relaxation at high frequencies. Thus, the I-relaxation of HDI-PU did not follow the superposition principle. The dielectric behaviors of the PUs were mainly influenced by their phase transitions, which were affected by the structure and components of the materials.

• Journal of Veterinary Science
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• v.22 no.4
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• pp.53.1-53.13
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• 2021

Background: Canine adipose-derived stem cells (cADSCs) exhibit various differentiation properties and are isolated from the canine subcutaneous fat. Although cADSCs are valuable as tools for research on adipogenic differentiation, studies focusing on adipogenic differentiation methods and the underlying mechanisms are still lacking. Objectives: In this study, we aimed to establish an optimal method for adipogenic differentiation conditions of cADSCs and evaluate the role of peroxisome proliferator-activated receptor gamma (PPARγ) and estrogen receptor (ER) signaling in the adipogenic differentiation. Methods: To induce adipogenic differentiation of cADSCs, 3 different adipogenic medium conditions, MDI, DRI, and MDRI, using 3-isobutyl-1-methylxanthine (M), dexamethasone (D), insulin (I), and rosiglitazone (R) were tested. Results: MDRI, addition of PPARγ agonist rosiglitazone to MDI, was the most significantly facilitated cADSC into adipocyte. GW9662, an antagonist of PPARγ, significantly reduced adipogenic differentiation induced by rosiglitazone. Adipogenic differentiation was also stimulated when 17β-estradiol was added to MDI and DRI, and this stimulation was inhibited by the ER antagonist ICI182,780. Conclusions: Taken together, our results suggest that PPARγ and ER signaling are related to the adipogenic differentiation of cADSCs. This study could provide basic information for future research on obesity or anti-obesity mechanisms in dogs.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.2
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• pp.102.2-102.2
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• 2011

Sunspots usually appear in a group which can be classified by certain morphological criteria. In this study we examine the moments which are statistical parameters computed by summing over every pixels of contours, in order to quantify the morphological characteristics of a sunspot group. The moments can be additional characteristics to the sunspot group classification such as McIntosh classification. We are developing a program for image processing, detection of contours and computation of the moments using continuum images from SOHO/MDI. We apply the program to count the sunspot numbers from 303 continuum images in 2003. The sunspot numbers obtained by the program are compared with those by SIDC. The comparison shows that they have a good correlation (r=89%). We are extending this application to automatic sunspot classification (e.g., McIntosh classification) and flare forecasting.

• Tuberculosis and Respiratory Diseases
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• v.39 no.6
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• pp.490-501
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• 1992

Background: Isocyanate is the most significant cause of occupational asthma in this country. The mechanism of isocyanate induced bronchoconstriction is unclear. Subjects and Method: To observe its immunologic and clinical findings, we performed methacholine bronchial challenge test (MBCT), toluene diisocyanate (TDI)-bronchoprovocation test (BPT) and RAST to TDI-, diphenylmethane diisocyanate (MDI)-, and hexamethylene diisocyanate (HDI)-human serum albumin (HSA) conjugate in 22 isocyanate-sensitive asthmatic workers. Results: BPT revealed early (11), dual (5), and late only (6) asthmatic responses. Their latent period ranged from 3 to 120 months (mean:45.9 months). Three cases (13.6%)showed a negative response on initial MBCT, but following MBeT performed 24 hours after TDI-BPT revealed the development of airway hyperresponsivenss. Twelve (54.5%) workers had increased specific IgE to TDI-HSA, seven (31.8%) had to MDI-HSA, and nine (40.9%) had to HDI-HSA conjugate. The prevalence of specific IgE was not associated with latent period, type of asthmatic responses, smoking, and atopic status. After 3 months' avoidance from workplace, airway hyperresponsiveness was improved in 10 (38.3%), among 12 followed cases. Conclusion: It is suggested that isocyanate can induce IgE-mediated bronchoconstriction in 59.1% of isocyanate-sensitive asthmatic workers. Isocyanate-induced asthma can occur even though MBeT showed a negative result, and measurement of the changes of airway hyperresponsivenss after isocyanate-BPT could be helpful to diagnose isocyanate-sensitive asthma.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.2
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• pp.60.2-61
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• 2017

A Convolutional Neural Network(CNN) is one of the well-known deep-learning methods in image processing and computer vision area. In this study, we apply CNN to two kinds of flare forecasting models: flare classification and occurrence. For this, we consider several pre-trained models (e.g., AlexNet, GoogLeNet, and ResNet) and customize them by changing several options such as the number of layers, activation function, and optimizer. Our inputs are the same number of SOHO)/MDI images for each flare class (None, C, M and X) at 00:00 UT from Jan 1996 to Dec 2010 (total 1600 images). Outputs are the results of daily flare forecasting for flare class and occurrence. We build, train, and test the models on TensorFlow, which is well-known machine learning software library developed by Google. Our major results from this study are as follows. First, most of the models have accuracies more than 0.7. Second, ResNet developed by Microsoft has the best accuracies : 0.77 for flare classification and 0.83 for flare occurrence. Third, the accuracies of these models vary greatly with changing parameters. We discuss several possibilities to improve the models.

• Journal of the Korean Wood Science and Technology
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• v.37 no.2
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• pp.121-127
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• 2009

Acacia wood (Acacia mangium Willd.) is the most popular fast growing tree species planted in timber estate in Indonesia and is considered to be very valuable raw materials for structural composite products. The objective of the research was to evaluate the properties of OSB prepared from A. Mangium wood with or without immersing the strands to hot water at $80^{\circ}C$ for 2 hours. MDI adhesive was used in 3 levels i.e., 3%, 5%, and 7%. The moisture content of strand was 7%. The results indicated that immersing strands in hot water for 2 hours at $80^{\circ}C$ prior to manufacture OSB improved significantly the mechanical peoperties (i.e., MOR and MOE) of OSB. The higher the adhesive content resulted in the better the dimensional stabilisation (i.e., water absorption and thickness swelling) and the mechanical properties (i.e., MOR, MOE and IB) of OSB. OSB prepared from hot-water immersed strands with 5% adhesive content has met all parameters requirement on the JIS A 5908 (2003) standard.

• Asia pacific journal of information systems
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• v.31 no.4
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• pp.582-605
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• 2021

The study aims to explore the nature, drivers of BAE. In particular, how and why consumers engage with branded mobile apps. Since consumer engagement is a multi-dimensional and complex phenomenon, the authors took an interpretivist paradigm and used a grounded theory approach by interviewing 24 participants. The findings reveal that branded app engagement (BAE) is triggered by mainly three aspects, i.e., media characteristics (Privacy and security, customization, and convenience), brand-related aspects (brand image and product/service quality), and benefits sought (inherent and derived). More importantly, we uncover the underlying mechanism for each factor. Furthermore, the study explains the BAE process in its entirety from an app-centric perspective rather the brand powering the app. Thus, the study offers a fresh perspective and novel insights into the BAE process.