• Applied Chemistry for Engineering
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• v.24 no.2
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• pp.171-176
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• 2013

The need of volatile organic compound (VOC) free coating material has been increased to solve environmental problems such as the global warming. Nowadays, about 70~80% of coating materials used in the worldwide are a liquid type. Therefore, the development of non-solvent coating material that can minimize VOCs emissions is necessary to solve the global warming problem. In this study, acrylic monomers were added to develop non-solvent paints in order to improve disadvantages of the poor adhesion of a conventional phenolic resin caused by acidification. As a result, the blend resins of 2.818 Mpa phenol- formaldehyde resin/poly methyl methacrylate (PE/PMMA) has the best properties and performances for the adhesives.

• International Journal of Safety
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• v.4 no.1
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• pp.14-17
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• 2005

Recycled polyol was obtained by glycolysis of MDI-based Polyurethane(PU) rigid foam. The chemical structure of the recycled pclyol was confirmed by GC(gas chromatography) and 1H-NMR. The recycled polyol throughout the glycolysis contained liquid polyol and methylenedianiline(MDA). MDA which could cause liver cancer is carcinogenic material. TWA(Time Weighted Average.) amount for MDA in MSDS(Material Safety Data Sheets) was confined less than 0.1 ppm. The melting temperature of MDA is $92^{\circ}C$, and boiling temperature is $398^{\circ}C$. During the gylcolysis most of MDA was dissolved in liquid polyol. The probability that MDA diffuses into the atmosphere is low but there could be an absorption of MDA into skin. Furthermore because MDA is amine compound, recycled polyol which contained MDA had a difficulty in reaction control of polyurethane. Therefore reduction of MDA amount was needed strongly. In this study the elimination of MDA were performed through deamination of the recycled polyol by glycidyl ether compounds. As glycolysis was proceeded, the amount of MDA was 9.8 wt % at early stage and increased up to 14.0 wt % after 8 hours reaction. It was found that 2-Ethylhexyl glycidyl ether which contains aliphatic moiety was very effective compound for eliminating the primary aromatic amine compound :md the optimal mole ratio of 2-ethylhexyl glycidyl ether to MAD was 3. The final polyol after deamination by 2-ethylhexyl glycidyl ether has an appropriate viscosity(less than 500 centi poise) for polyurethane reaction.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.1
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• pp.51-56
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• 2015

The object of this study is to obtain the optimum mix proportion of halogen free compound with flame resistance and, for the purpose, thermal/electrical characteristics test are conducted using compatibilizing agents, flame resistance agents, hydroxide aluminum, sunscreen, antioxidant and silicon oil on the base resin of linear low density polyethylene (LLDPE), Ethylene vinyl acetate copolymer (EVA). Existing compound method accompanies many requirements to be satisfied including a lot of addition of flame resistance agents, prohibition of impact on mixing capability with base and property and etc. In this study, different from the existing method, the optimum mix proportion is determined and experimented by adding nano clay. Oxygen index test shows no difference between specimens while T-6, T-9 shows oxygen index of 29[%] and 26[%], respectively. This is concluded that hydroxide aluminum, which is a flame resistance agent, leads low oxygen index. From UL94-V vertical flame resistance test, the combustion behavior is determined as V-0, Fail based on UL94-V decision criteria. Viscometry shows low measurements in specimens with separate addition of compatibilizing agents or nano clay. Volume resistivity test shows low measurement mainly in specimens without compatibilizing agents. Therefore, with the flame resistance compound shows better performance for thermal/electrical property and the optimum mix proportion are achieved among many existing materials.

• Elastomers and Composites
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• v.42 no.4
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• pp.232-237
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• 2007

We examined the properties of compound and made compound of the optimum state using the properties of each material to evaluate suitability of FKM, VMQ, EPDM, NBR with gasket for fuel cell which is in general use with the material of gasket. It could be found from the compound made with setting the optimum state that NBR is worse than FKM in the chemical property of matter for a long term, and VMQ is worse than FKM in the elution of a metal ion, and EPDM is worse than FKM in the permeability of gas. As a result of leak evaluation of gasket for fuel cell with using FKM, it appeared leak in short time when contracting pressure is getting lower and sealing pressure is getting higher. And as a result of the life prediction with using Arrhenius model, we could predict that it is possible to continuously drive for 60,000 hours.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.43 no.3
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• pp.195-200
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• 2017

This study was conducted to examine the inhibitory effects of meso-dihydroguaretic acid (MDGA, 1) and its synthetic derivatives (compound 2 and 3) against NO production. MDGA is a lignan component isolated from the bark of Machilus thunbergii Sieb. et Zucc. We synthesized dimethylated MDGA (2), diacetylated MDGA (3) and compared NO inhibition of two derivatives with that of MDGA (1). MDGA (1) and compound 3 showed suppressive effects against the generation of NO in LPS-activated macrophages. RT-PCR analysis suggested that MDGA (1) and compound 3 inhibited NO production through the suppression of iNOS mRNA expression. From these results, diacetylated MDGA (3) can be used as a pro-drug for MDGA.

• Elastomers and Composites
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• v.38 no.1
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• pp.72-80
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• 2003

Phosphoric ester compound was employed as thermal resistant and flame retardant for chlorinated polyethylene(CPE) rubber material which is used to prepare automotive oil cooler hose. Cure characteristics, physical properties, thermal resistance, and flame retardation of CPE rubber compounds were investigated. CPE rubber which has excellent properties such as cold resistance and chemical corrosion resistance, and is inexpensive in price than existing ethyleneacrylate rubber(EAR) was used to prepare a rubber compound useful for hose. A non-halogen flame retarding agent N,N'-bis- (diphenylphosphoro) diaminohexane(BDPDH), which is condensed phosphoric ester, was synthesized and it was mixed to CPE rubber material with the range of $0{\sim}30 phr$. From the test results, rheological properties, heat resistance, and flame retardance of CPE rubber compounds were found out to be much increased. The optimum content of BDPDH to rubber which gives maximum effect on thermal resistance and flame retardation, within the range of tolerable specification for rubber materials, was determined to be 20 phr.

• Journal of Ginseng Research
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• v.46 no.2
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• pp.304-314
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• 2022

Background: Ginsenosides are biologically active components of ginseng and have various functions. In this study, we investigated the immunomodulatory activity of a ginseng product generated from ginseng powder (GP) via enzymatic bioconversion. This product, General Bio compound K-10 mg solution (GBCK10S), exhibited increased levels of minor ginsenosides, including ginsenoside-F1, compound K, and compound Y. Methods: The immunomodulatory properties of GBCK10S were confirmed using mice and a human natural killer (NK) cell line. We monitored the expression of molecules involved in immune responses via enzyme-linked immunosorbent assay, flow cytometry, NK cell-targeted cell destruction, quantitative reverse-transcription real-time polymerase chain reaction, and Western blot analyses. Results: Oral administration of GBCK10S significantly increased serum immunoglobulin M levels and primed splenocytes to express pro-inflammatory cytokines such as interleukin-6, tumor necrosis factor-α, and interferon-γ. Oral administration of GBCK10S also activated NK cells in mice. Furthermore, GBCK10S treatment stimulated a human NK cell line in vitro, thereby increasing granzyme B gene expression and activating STAT5. Conclusion: GBCK10S may have potent immunostimulatory properties and can activate immune responses mediated by B cells, Th1-type T cells, and NK cells.

• Journal of the Microelectronics and Packaging Society
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• v.29 no.4
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• pp.83-87
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• 2022

Recently, as the thickness of the semiconductor package becomes thinner, warpage has become a major issue. Since the warpage is caused by differences in material properties between package components, it is essential to precisely evaluate the material properties of the EMC(Epoxy molding compound), one of the main components, to predict the warpage accurately. Especially, the cure shrinkage of the EMC is generated during the curing process, and among them, the effective cure shrinkage that occurs after the gelation point is a key factor in warpage. In this study, the gelation point of the EMC was defined from the dissipation factor measured using the dielectric sensor during the curing process similar with actual semiconductor package. In addition, DSC (Differential scanning calorimetry) test and rheometer test were conducted to analyze the dielectrometry measurement. As a result, the dielectrometry was verified to be an effective method for monitoring the curing status of the EMC. Simultaneously, the strain transition of the EMC during the curing process was measured using the FBG (Fiber Bragg grating) sensor. From these results, the effective cure shrinkage of the EMC during the curing process was measured.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.5
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• pp.397-404
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• 2009

Effects of ceramic filler types and dose on the low temperature sintering and dielectric properties of ceramic/$CaO-Al_2O_3-SiO_2$ (CAS) glass composites were investigated. All of the specimens were sintered at $850{\sim}900^{\circ}C$ for 2 h, which conditions are required by the low-temperature co-firing ceramic (LTCC) technology. Ceramic fillers of $CaCO_3$, $Al_2O_3$, $CaCO_3-Al_2O_3$ mixture, and $CaCO_3-Al_2O_3$ compound ($CaAl_2O_4$), respectively, were used. The addition of $Al_2O_3$ yielded the crystalline phase of alumina, which was associated with the inhibition of sintering, while, $CaCO_3$ resulted in no apparent crystalline phase but the swelling was significant. The additions of $CaCO_3-Al_2O_3$ mixture and $CaAl_2O_4$, respectively, yielded the crystalline phases of alumina and anorthite, and the sintering properties of both composites increased with the increase of filler addition and the sintering temperature. In addition, the $CaAl_2O_4$/CAS glass composite, sintered at $900^{\circ}C$, demonstrated good microwave dielectric properties. In overall, all the investigated fillers of 10 wt% addition, except $CaCO_3$, yielded reasonable sintering (relative density, over 93 %) and low dielectric constant (less than 5.5), demonstrating the feasibility of the investigated composites for the application of the LTCC substrate materials.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.304.2-304.2
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• 2014

Chalcogenides (Te,Se) and pnictogens(Bi,Sb) materials have been widely investigated as thermoelectric materials. Especially, Bi2Te3 (Bismuth telluride) compound thermoelectric materials in thin film and nanowires are known to have the highest thermoelectric figure of merit ZT at room temperature. Currently, the thermoelectric material research is mostly driven in two directions: (1) enhancing the Seebeck coefficient, electrical conductivity using quantum confinement effects and (2) decreasing thermal conductivity using phonon scattering effect. Herein we demonstrated influence of annealing temperature on structural and thermoelectrical properties of Bismuth-telluride-selenide ternary compound thin film. Te-rich Bismuth-telluride-selenide ternary compound thin film prepared co-deposited by thermal evaporation techniques. After annealing treatment, co-deposited thin film was transformed amorphous phase to Bi2Te3-Bi2Te2Se1 polycrystalline thin film. In the experiment, to investigate the structural and thermoelectric characteristics of Bi2Te3-i2Te2Se1 films, we measured Rutherford Backscattering spectrometry (RBS), X-ray diffraction (XRD), Raman spectroscopy, Scanning eletron microscopy (SEM), Transmission electron microscopy (TEM), Seebeck coefficient measurement and Hall measurement. After annealing treatment, electrical conductivity and Seebeck coefficient was increased by defect states dominated by selenium vacant sites. These charged selenium vacancies behave as electron donors, resulting in carrier concentration was increased. Moreover, Thermal conductivity was significantly decreased because phonon scattering was enhanced through the grain boundary in Bi2Te3-Bi2Te2Se1 polycrystalline compound. As a result, The enhancement of thermoelectric figure-of-merit could be obtained by optimal annealing treatment.