• The Korean Journal of Zoology
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• v.30 no.1
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• pp.89-98
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• 1987

The research of fused oocytes was conducted to investigate the in vitro mejotic maturation of immature oocytes (GV oocytes) fused with oocytes in germinal vesicle breakdown (GVBD oocytes) in the presence of dbcAMP which is known as one of the strong inhibitors to GVBD. The immature oocytes fused together as well as those fused with GVBD oocytes proceeded to GVBD in 3 hr culture in plain medium. But in the medium containing dbcAMP (100$\mu$g/ml), the immature oocytes fused together did not show any GVBD and thus the fusion itself could not affect the inhibitory activity of dbcAMP. However, all of the immature oocytes fused with GVBD oocytes underwent GVBD in 3 hr culture despite of the presence of dbcAMP. When the culture was extended to 20 hr, nearly all of the immature oocytes fused together were still arrested at the GV stage in the presence of dbcAMP. But most of the fused oocytes which had shown GVBD during 3 hr culture developed to metaphase II stage extruding one or two polar bodies regardless of the presence of dbcAMP. In this experiment, it was found that two sets of the metaphase chromosomes were somewhat concomitant with a pair of the polar bodies in the fused egg. Upon the results of the present studies, it is assumed that there may be a maturation promoting factor(s) in the cytoplasm of the GVBD occytes, and this factor(s) possibly nullifies the function of dbcAMP.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.38 no.3
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• pp.255-261
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• 2012

The skin is continuously exposed to environmental stresses. One of the most important stress factor is UV radiation. UV radiation causes a variety of biological effects on the skin, including inflammation, pigmentation, photoaging and cancer. Therefore in this study, we tried to search for skin-protective antioxidant materials from marine natural products (Porphyra Thalli, Laminariae japonicae thallus, Ostreae Concha, Sargassum Thallus, Undaria thallus, Haliotidis Concha, Agar, Codium thalli, Hizikia fusiforme thalli; HFE, Thalli) which exhibit protective activities against UVB-induced cytotoxicity and oxidative cell death and antiaging effects. As a results, UVB-induced cytotoxicity and cell death were effectively suppressed by treatment of Sargassum Thallus, Agar, Haliotidis Concha, Codium thalli, Thalli ethanol extracts. UVB-induced cell death was mediated by intracellular accumulation or ROS, which was significantly inhibited by treatment with marine natural products extracts. Also, The protective effect of these marine natural products seemed to be mediated by increased expression of type I collagen and Type I procollagen. These results suggest that marine natural products may have anti-aging effects new functional materials against oxidative stress-mediated skin damages.

• Journal of Convergence for Information Technology
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• v.10 no.1
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• pp.22-27
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• 2020

With the deployment of 5G infrastructure, content delivery network (CDN) will be a key role to provide explosive growing services for the independent media and YouTube which contain high-speed mobile contents. Without a local cache, the mobile backhaul and fronthaul should endure huge burden of bandwidth request for users as the increase number of direct accesses from contents providers. To deal with this issue, this paper fist presents both fronthaul solutions for CDN that use dark fibers and a passive optical network (PON). On top of that, we propose the aggregated content request specialized for PON caching and evaluate and compare its performance to legacy schemes through the simulation. The proposed PON caching scheme can reduce average access time of up to 0.5 seconds, 1/n received request packets, and save 60% of backhaul bandwidth compared to the no caching scheme. This work can be a useful reference for service providers and will be extended to further improve the hit ratio of cache in the future.

• Korean Journal of Food Science and Technology
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• v.41 no.6
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• pp.700-705
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• 2009

Several studies have demonstrated that chlorophyll has many beneficial properties, including anti-inflammatory, anti-tumor, and antioxidant properties. Chlorophyll has been also shown to have an excellent chemopreventive potential against skin tumor. Its preventive mechanism against skin tumor, however, has not been examined in detail. Furthermore, the effects of chlorophyll on UVB-induced cellular responses have not been investigated. Solar UV radiation, in particular its UVB component, is the primary cause of many adverse biological effects, which is responsible for the photoaging and skin cancer. We investigated the preventive effects of chlorophyll a on UVB-mediated responses in human immortalized HaCaT kerationocytes and normal human fibroblast. We found that treatment of chlorophyll a markedly inhibited UVB-induced generation of reactive oxygen species and lipid peroxidation. Chlorophyll a also prevented UVB-induced MMP-1 expression and MMP-2 activation and increased Type I pN collagen synthesis. These results suggest that chlorophyll a is a potent candidate for the prevention and treatment of UVB-induced skin cancer and photoaging.

• Journal of the Korean Chemical Society
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• v.22 no.1
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• pp.30-36
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• 1978

The kinetics of hydrolysis of ${\alpha}$-nitrobenzaldehydephenylhydrazone derivatives (p-$NO_2$, m-$NO_2$, p-Cl, p-$CH_3$) have been investigated by UV spectrometry in 25% dioxane-water at $25^{\circ}C$ and a rate equation which can be applied over wide pH range was obtained. From the rate equation and the effect of solvent, substituent and pKa on the rate equation, the following reaction mechanisms were proposed. Below pH 3.0 the hydrolysis of ${\alpha}$-nitrobenzaldehydephenylhydrazone proceeds by $S_N1$ mechanism, while above pH 4.0 the hydrolysis proceeds through 1,3-dipole ion mechanism. In the range of pH from 3.0 to 4.0 these two reactions occur competitively.

• Korean Journal of Plant Tissue Culture
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• v.25 no.4
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• pp.257-261
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• 1998

The repeated subcultures of in vitro plant materials in wasabi became highly vitrified and the capacity for multiple shoot formation from the vitrified plant materials was very low. In order to improve the quality of in vitro propagated planting materials, the experiments were carried out using culture vessels capped with membrane filter(MF). When vitrified shoots were cultured on MS medium with 0.2mg/L BA in the vessels with MF or without MF for 60 days, the shoots in the vessels with MF did not vitrified. In contrast, the shoots grown in the vessels without MF vitrified at 65%. The stomates of vitrified leaves were circular and inflated, whereas those of normal leaves acclimatizated in the vessels with MF were ovate in shape. The hardened shoots were also cultured on MS media without sucrose containing 0.01mg/L IBA in vessels with(photoautotrophic culture) or without(control) MF. Sucrose was necessary for survival of the in vitro plantlets in the vessels without MF. After 20 days of culture, the shoots in the vessels without MF on the sucrose-free media turned yellow and died. But the shoots in the vessels with MF in the sucrose-free media produced a lot of roots. When shoots were cultured on MS medium with 2% sucrose containing 0.01mg/L IBA in the vessels with(photomixotrophic culture) or without(heterotrophic culture) MF, best growth occured in photomixotrophic culture.

• Journal of Korean Tunnelling and Underground Space Association
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• v.4 no.3
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• pp.229-234
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• 2002

Nowadays, the blast method is mainly operated in the fields of the rock excavation accompanied by construction site in Korea. Blast method has many merits such as improvement of workability, reducement of operation period, and etc. However, blast operation also create much loss and troubles with the neighbours for the environmental pollutions such as the noise, blast vibration, fly rocks and dusts. Thus, the non-vibration and shallow vibration methods have been used but they have also another problems in the view of the economy and the efficiency in operation. In this study, we had made laboratory tests for the breaking of the various Rock types by White Light Thermal Stress. The tests shows that one unit consuming 500kilowatts of electricity, would go 90 feet a day in tunneling if the tunnel was 16 feet by 16 feet. Also, if a faster rate of tunneling could be handled, other white light units could be added.

• Applied Chemistry for Engineering
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• v.26 no.3
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• pp.372-376
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• 2015

6-MQCC (Cr(VI)-6-methylquinoline) complex was synthesized by the reaction of 6-methylquinoline with chromium(VI) trioxide in 6 M HCl. The structure was characterized using IR (Infrared Spectroscopy) and ICP (Inductively Coupled Plasma) analysis. The oxidation of benzyl alcohol using 6-MQCC in various solvents showed that the reactivity increased with the increase of the dielectric constant, in descending order of DMF > acetone > chloroform > cyclohexene. In the presence of DMF solvent with acidic catalyst such as sulfuric acid ($H_2SO_4$), 6-MQCC oxidized benzyl alcohol (H) and its derivatives ($p-OCH_3$, $m-CH_3$, $m-OCH_3$, m-Cl, $m-NO_2$) were effectively oxidized. Electron-donating substituents accelerated the reaction rate, whereas electron acceptor groups retarded the reaction rate. The Hammett reaction constant (${\rho}$) was -0.69 (308 K). The observed experimental data was used to rationalize the fact that the hydride ion transfer occurred at the rate-determining step.

• Journal of the Korean Chemical Society
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• v.45 no.1
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• pp.7-13
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• 2001

The interaction of benzenesulfonate anion and its derivatives ($C_6H_5SO_3^-, p-$CH_3C_6H_4SO_3^-, and $p-C_2H_5C_6H_4SO_3^-$) with the micellar system of cationic surfactant TTAB(tetradecyltrimethylammonium bromide) was studied by UV/Vis spectrophotometric method. The solubilization constants($K_s$) of benzenesulfonate anions into the micellar phase of this surfactant have been measured with the change of temperature. The effects of additives(n-pentanol and NaBr) on the solubilization of benzenesulfonate anions by this surfactant system have been also measured. There was a great decrease on the values of $K_s$ and CMC simultaneously with these additives so that the measured values of ln$K_s$ were linear relationships with the values of lnCMC. For the thermodynamic study, various thermodynamic parameters(${\Delta}G^0_s$, ${\Delta}H^0_s$ and ${\Delta}S^0_s$) have been calculated and analyzed from the dependence of Ks values on temperature.

• Applied Chemistry for Engineering
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• v.27 no.1
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• pp.110-114
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• 2016

Cr(VI)-pyrazine complex (PZCC) was synthesized by the reaction of pyrazine with chromium (VI) trioxide in 6 M HCl. The structure was characterized using IR spectroscopy and inductively coupled plasma (ICP). The oxidation of benzyl alcohol using PZCC in various solvents showed that the reactivity increased with the increase of the dielectric constant, in the order: N,N'-dimethylform-amide > acetone > chloroform > cyclohexene. In the presence of N,N'-dimethylformamide solvent with an acidic catalyst such as sulfuric acid ($H_2SO_4$ solution), PZCC oxidized benzyl alcohol (H) and its derivatives ($p-OCH_3$, $m-CH_3$, $m-OCH_3$, m-Cl, $m-NO_2$). Electron-donating substituents accelerated the reaction rate, whereas electron acceptor groups retarded the reaction rate. Hammett reaction constant (${\rho}$) was -0.70 (308 K). The observed experimental data were used to rationalize the hydride ion transfer in the rate-determining step.