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Hwang, Tae-Yong,Lee, Jae-Wook,Lee, Sang-Min,Nam, Gi-Joon The Polymer Society of Korea 2009 Macromolecular Research Vol.17 No.2
The cure kinetics of the epoxy-layered, silicate nanocomposites were studied by differential scanning calorimetry under isothermal and dynamic conditions. The materials used in this study were o-cresol novolac epoxy resin and phenol novolac hardener, with organically modified layered silicates. Various kinetic parameters, including the reaction order, activation energy, and kinetic rate constants, were investigated, and the storage stability of the epoxy-layered silicate nanocomposites was measured. To synthesize the epoxy-layered silicate nanocomposites, the phenolic hardener underwent pre-intercalation by layered silicate. From the cure kinetics analyses, the organically modified layered silicate decreased the activation energy during cure reaction in the epoxy/phenolic hardener system. In addition, the storage stability of the nanocomposite with the pre-intercalated phenolic hardener was significantly increased compared to that of the nanocomposite with direct mixing of epoxy, phenolic hardener, and layered silicate. This was due to the protective effect of the reaction between onium ions and epoxide groups.
Hwang, Seok-Jo,Byeon, Young-Woong,Lee, Seol-Mae,Kim, Jeong-Hwan,Choi, Man-Young,Kim, Sung-Hyun,Kim, Nam-Jeong,Park, Hae-Chul,Lee, Young-Bo,Lee, Sang-Beom,Lee, Jong-Wook Korean Society of Sericultural Science 2010 International Journal of Industrial Entomology Vol.21 No.2
This study was performed to investigate the temperature-dependent development, longevity and oviposition of an indigenous larval parasitoid, Meteorus pulchricornis, on tobacco cutworm, Spodoptera litura. M. pulchricornis were reared at nine constant temperatures between 15 and $35^{\circ}C$. The developmental times of each three developmental stage decreased from 38.7 to 16.3 d between 15 and $30^{\circ}C$. However, M. pulchricornis showed longer developmental time at $32.5^{\circ}C$ (9.5, 7.7 and 17.2 days for each three developmental stage) than at $30^{\circ}C$ (8.9, 7.3 and 16.3 days for each three developmental stage). Immature M. pulchricornis could not develop any more at $35^{\circ}C$. The lower developmental threshold estimated by linear regression equation for the egg to cocoon, cocoon to adult emergence and egg to adult emergence were 5.1, 4.6 and $4.5^{\circ}C$. The thermal constant for each of the three stages were 217.2, 176.2 and 403.8 degree-days, respectively. When no food or 50% honey solution as a food source is provided for M. pulchricornis, the parasitoid survived for 8.3 and 55.9 days at $25^{\circ}C$, respectively. M. pulchricornis females laid 5.2 eggs daily and total of 131.6 eggs at $25^{\circ}C$ until it died. Peak age-specific fecundity was observed on $14^{th}$ day (9.6 cocoons) after parasitoid emergence and gradually decreased thereafter.
Effect of the Cool-roof System on Thermal Rooftop Environments
Sang-Hyun Park,Ji-Hun Park,Seon-Wook Hwang,Yujin Kang,Sumin Kim 한국생활환경학회 2017 한국생활환경학회지 Vol.24 No.1
The cool-roof system has emerged as a solution for the heat-island phenomenon through its minimization of the absorption of solar radiation. In the present study, an effect on the interior thermal environment was confirmed after the application of the cool-roof system on rooftops for the Cool Roof Campaign. The effect of the cool-roof system was measured according to the surface temperature and the indoor and outdoor temperatures that were recorded three times before and three times after the construction process, as well as on the first post-construction day. Through a determination of the thermal rooftop environment, the reduction ratio of the exterior-surface temperature was measured and the indoor and outdoor temperatures were compared. In addition, the interior thermal environment was evaluated by roof color with the colors green, white, and gray, and scale-model experiments were conducted under the same conditions. According to the results, the bright-color cool-roof system is highly efficient in terms of the reflection of solar radiation and the reduction of the surface temperature, and this is because of its higher reflectance and lower absorptance. Consequently, the use of the cool-roof system can decrease both the indoor temperature and the cooling energy in summer.
Hwang, In-Wook,Kim, Bo-Min,Kim, Young-Chan,Lee, Sang-Han,Chung, Shin-Kyo The Korean Society for Applied Biological Chemistr 2018 Applied Biological Chemistry (Appl Biol Chem) Vol.61 No.2
In this study, the high-pressure steaming and enzymatic pre-treatment (SET) was used to improve ${\beta}$-glucan extraction from Ganoderma lucidum (G. lucidum), an oriental medicinal mushroom. Response surface methodology and central composite design were used to determine the optimum pre-treatment conditions: high-pressure steaming, enzymatic hydrolysis, and Viscozyme L concentrations. The optimal conditions were 15.51 min for high-pressure steaming, 0.84 g/100 mL of Viscozyme L, and 4.16 h for hydrolysis. The predicted ${\beta}$-glucan content in G. lucidum extract at optimal conditions, approximately twofold (8.05 g/100 g) of the control treatment value, was consistent with the empirical value. The total sugar and protein contents through SET were higher than those values of the control treatment. The cell migration assay showed that SET-processed G. lucidum extracts significantly suppressed B16F10 murine melanoma cell growth. SET process using Viscozyme L could be utilized for ${\beta}$-glucan extraction from G. lucidum to develop the functional food.
Antimorphic PV.1 Causes Secondary Axis by Inducing Ectopic Organizer
Hwang, Yoo-Seok,Seo, Jeong-Jae,Cha, Sang-Wook,Lee, Hyun-Shik,Lee, Sung-Young,Roh, Dong-Hyun,Kung, Hsiang-fu,Kim, Jaebong,Park, Mae Ja 경북대학교 병원 2002 경북대학교병원의학연구소논문집 Vol.6 No.1
Xenopus homeobox gene, PV.1 ventralizes activininduceddorsal mesoderm and inhibits neuralization of ectoderm in animal cap when overexpressed. Here we generated PV.1/engrailed fusion construct (N-PV1-EnR) to perform loss-of-function study for this transcription factor.N-PV1-EnR showed an extremely antimorphic effect, causing a partial secondary embryonic axis when expressed at ventral marginal zone of blastula. In ventral marginal zone cells, this chimeric protein induced organizer genes and suppressed ventral markers mimicking those effects reported for dominant negative BMP-4 receptor (DNBR).Moreover, N-PV1-EnR rescued the ventralized embryos caused by the ectopic dorsal expression of PV.1 but not by that of Xvent-2. These results suggested that PV.1 functions at downstream of BMP-4 as a ventralizing effector which acts separately from Xvent-2 and the dominant negative effect gained by this specific mutant is applicable for the further studiesof BMP-4 downstream pathway.
Observation of Moisture Content in Wood at Non-Steady State
Hwang, Sung-Wook,Lee, Won-Hee Korea Furniture Society 2009 한국가구학회지 Vol.20 No.6
For the search of unified law of moisture movement in wood, moisture distribution of Korean red pine at non-steady state was investigated. We assume that the equilibrium moisture content (EMC) in wood depends on only temperature and relative humidity, it can be control in temperature and humidity chamber. If temperature is constant and humidity or vapor pressure is changed with sin curve shape at adequate cycles, EMC in chamber can be changed as well with sin-curve shape. The setup condition of a non-steady state in humidity control chambers is a constant temperature at $20^{\circ}C$ and 15+10 sin ${\omega}t$ percent EMC. It can be found that the distribution of moisture in the specimen with varying relative humidity are illustrated various types. Moisture in wood is complicated and vibrates with the moisture sorption process. Considering a unified law of moisture movement in wood, it is considered that the most important fact is to search the method of precise diffusion & transfer coefficients.
Pharmacological Stimulation of NADH Oxidation Ameliorates Obesity and Related Phenotypes in Mice
Hwang, Jung Hwan,Kim, Dong Wook,Jo, Eun Jin,Kim, Yong Kyung,Jo, Young Suk,Park, Ji Hoon,Yoo, Sang Ku,Park, Myung Kyu,Kwak, Tae Hwan,Kho, Young Lim,Han, Jin,Choi, Hueng-Sik,Lee, Sang-Hee,Kim, Jin Man,L American Diabetes Association 2009 Diabetes Vol.58 No.4
<P><B>OBJECTIVE</B></P><P>Nicotinamide adenine dinucleotides (NAD<SUP>+</SUP> and NADH) play a crucial role in cellular energy metabolism, and a dysregulated NAD<SUP>+</SUP>-to-NADH ratio is implicated in metabolic syndrome. However, it is still unknown whether a modulating intracellular NAD<SUP>+</SUP>-to-NADH ratio is beneficial in treating metabolic syndrome. We tried to determine whether pharmacological stimulation of NADH oxidation provides therapeutic effects in rodent models of metabolic syndrome.</P><P><B>RESEARCH DESIGN AND METHODS</B></P><P>We used β-lapachone (βL), a natural substrate of NADH:quinone oxidoreductase 1 (NQO1), to stimulate NADH oxidation. The βL-induced pharmacological effect on cellular energy metabolism was evaluated in cells derived from NQO1-deficient mice. In vivo therapeutic effects of βL on metabolic syndrome were examined in diet-induced obesity (DIO) and <I>ob/ob</I> mice.</P><P><B>RESULTS</B></P><P>NQO1-dependent NADH oxidation by βL strongly provoked mitochondrial fatty acid oxidation in vitro and in vivo. These effects were accompanied by activation of AMP-activated protein kinase and carnitine palmitoyltransferase and suppression of acetyl-coenzyme A (CoA) carboxylase activity. Consistently, systemic βL administration in rodent models of metabolic syndrome dramatically ameliorated their key symptoms such as increased adiposity, glucose intolerance, dyslipidemia, and fatty liver. The treated mice also showed higher expressions of the genes related to mitochondrial energy metabolism (PPARγ coactivator-1α, nuclear respiratory factor-1) and caloric restriction (Sirt1) consistent with the increased mitochondrial biogenesis and energy expenditure.</P><P><B>CONCLUSIONS</B></P><P>Pharmacological activation of NADH oxidation by NQO1 resolves obesity and related phenotypes in mice, opening the possibility that it may provide the basis for a new therapy for the treatment of metabolic syndrome.</P>