• Journal of the Mineralogical Society of Korea
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• v.27 no.4
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• pp.169-181
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• 2014

Korea government has consistently investigated the development of economic mineral deposits in the Tofua volcanic arc, Tonga since 2008 for the secure of sea floor mineral resources. We studied the composition and distribution of minerals formed by hydrothermal activity around TA 25 seamounts of the Tofua volcanic arc, Lau Basin, Tonga, using X-ray diffraction analysis, scanning electron microscopy, X-ray fluorescence spectrometry, and inductively coupled plasma atomic emission spectrometry. We used 7 core samples and 9 surface sediment samples. Barite, sphalerite, and clinoclase are present in the most volcanic vent area. Gypsum, smectite, and kaolin mineral are distributed in vent A area, chalcopyrite, pyrite, smectite, and kaolin mineral are in vent B and C area, and gypsum, chalcopyrite, pyrite, and goethite are in vent D area. From the study of clay fraction, smectite and few kaolinite are detected in the most studied area except inner part of caldera, which suggest that argillic alteration are dominant in the volcanic vent areas. Various sulfide or arsenide minerals were found in the hydrothermal vent B, C, and D. The mineralogy and geochemistry suggest higher hydrothermal activities in volcanic vent B, C, and D compared to vent A and inner caldera area. Therefore higher probabilities of massive sulfide deposits may occur in hydrothermal vent B, C, and D.

• Progress in Medical Physics
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• v.19 no.1
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• pp.73-79
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• 2008

Retinal prosthesis is regarded as the most feasible method for the blind caused by retinal diseases such as retinitis pigmentosa (RP) or age related macular degeneration (AMD). Recently Korean consortium launched for developing retinal prosthesis. One of the prerequisites for the success of retinal prosthesis is the optimization of the electrical stimuli applied through the prosthesis. Since electrical characteristics of degenerate retina are expected to differ from those of normal retina, we performed voltage stimulation experiment both in normal and degenerate retina to provide a guideline for the optimization of electrical stimulation for the upcoming prosthesis. After isolation of retina, retinal patch was attached with the ganglion cell side facing the surface of microelectrode arrays (MEA). $8{\times}8$ grid layout MEA (electrode diameter: $30{\mu}m$, electrode spacing: $200{\mu}m$, and impedance: $50k{\Omega}$ at 1 kHz) was used to record in-vitro retinal ganglion cell activity. Mono-polar electrical stimulation was applied through one of the 60 MEA channel, and the remaining channels were used for recording. The electrical stimulus was a constant voltage, charge-balanced biphasic, anodic-first square wave pulse without interphase delay, and 50 trains of pulse was applied with a period of 2 sec. Different electrical stimuli were applied. First, pulse amplitude was varied (voltage: $0.5{\sim}3.0V$). Second, pulse duration was varied $(100{\sim}1,200{\mu}s)$. Evoked responses were analyzed by PSTH from averaged data with 50 trials. Charge density was calculated with Ohm's and Coulomb's law. In normal retina, by varying the pulse amplitude from 0.5 to 3V with fixed duration of $500{\mu}s$, the threshold level for reliable ganglion cell response was found at 1.5V. The calculated threshold of charge density was $2.123mC/cm^2$. By varying the pulse duration from 100 to $1,200{\mu}s$ with fixed amplitude of 2V, the threshold level was found at $300{\mu}s$. The calculated threhold of charge density was $1.698mC/cm^2$. Even after the block of ON-pathway with L-(1)-2-amino-4-phosphonobutyric acid (APB), electrical stimulus evoked ganglion cell activities. In this APB-induced degenerate retina, by varying the pulse duration from 100 to $1200{\mu}s$ with fixed voltage of 2 V, the threshold level was found at $300{\mu}s$, which is the same with normal retina. More experiment with APB-induced degenerate retina is needed to make a clear comparison of threshold of charge density between normal and degenerate retina.

• Progress in Medical Physics
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• v.19 no.3
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• pp.157-163
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• 2008

Retinal prosthesis is regarded as the most feasible method for the blind caused by retinal diseases such as retinitis pigmentosa or age-related macular degeneration. One of the prerequisites for the success of retinal prosthesis is the optimization of the electrical stimuli applied through the prosthesis. Since electrical characteristics of degenerate retina are expected to differ from those of normal retina, we investigated differences of the retinal waveforms in normal and degenerate retina to provide a guideline for the optimization of electrical stimulation for the upcoming prosthesis. After isolation of retina, retinal patch was attached with the ganglion cell side facing the surface of microelectrode arrays (MEA). $8{\times}8$ grid layout MEA (electrode diameter: $30{\mu}m$, electrode spacing: $200{\mu}m$, and impedance: 50 $k{\Omega}$ at 1 kHz) was used to record in-vitro retinal ganglion cell activity. In normal mice (C57BL/6J strain) of postnatal day 28, only short duration (<2 ms) retinal spikes were recorded. In rd/rd mice (C3H/HeJ strain), besides normal spikes, waveform with longer duration (~100 ms), the slow wave component was recorded. We attempted to understand the mechanism of this slow wave component in degenerate retina using various synaptic blockers. We suggest that stronger glutamatergic input from bipolar cell to the ganglion cell in rd/rd mouse than normal mouse contributes the most to this slow wave component. Out of many degenerative changes, we favor elimination of the inhibitory horizontal input to bipolar cells as a main contributor for a relatively stronger input from bipolar cell to ganglion cell in rd/rd mouse.

• Journal of Periodontal and Implant Science
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• v.34 no.4
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• pp.781-790
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• 2004

골아세포의 생물학적 기능을 증진시키기 위해 키토산의 표면개질에 대하여 연구하였다. 생체적합성 천연고분자인 키토산은 1차 아미노기를 소유하고 있으므로 적정한 공유결합제를 사용하여 세포성장인자와 같은 생리활성을 지닌 단백질을 키토산의 표면에 고정시킬 수 있다. 본 연구에서는 키토산을 필름형태로 제조하여 세포성장인자 중 형질전환성장인자를 고정하고 골아세포의 부착, 성장 및 분화를 증가시키고자 하였다. 형태전환성장인자의 고정화 효율은 단순한 흡착방법에 비해 높았으며, 표면에 형성된 공유결합은 매우 안정하였다. 골아세포를 배양하여 초기세포부착능에 대한 영향을 연구한 결과, 배양 후 4시간, 1일째, 형질전환성장인자를 고정한 키토산 표면에서 고정하지 않은 키토산의 표면에 비해 더 많은 수의 골아세포가 부착되었고, 더 많이 신장된 부착형태를 보였다. 세포활성정도와 배양 후 4주일째의 칼슘축적량을 측정한 결과, 형질전환성장인자를 고정한 키토산 표면에서 고정하지 않은 키토산의 표면에 비해 더 높았다. 위의 결과는 키토산 표면에 형태전환성장인자의 고정이 성공적으로 이루어졌으며, 또한 실제로 활성이 있는 것이 증명되었다. 위의 연구 결과에서 형질전환성장인자로 고정된 키토산은 골아세포의 초기 부착 및 분화를 촉진시켰음을 알 수 있었던 바 성장인자의 표면고정은 임플란트 및 조직공학용 지지체에도 적용하여 생체적합성과 세포기능을 증진시키는데 이용할 수 있음을 알 수 있었다.

• Journal of the korean academy of Pediatric Dentistry
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• v.28 no.1
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• pp.129-141
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• 2001

When oral microorganisms were sampled from occlusal surfaces of caries and non-caries teeth, $3.43\times10^5$ CFU and $3.47\times10^3$ CFU of bacteria were counted on MSB agar plates, respectively. All the 20 colonies isolated from a caries surface were Streptococcus mutans but, only two of 20 colonies were identified as Streptococcus mutans by API test. S. mutans SM1 from caries tooth and S. mutans SM2 from non-caries tooth showed the same results except for $\alpha-galactosidase$ activity on sugar fermentation tests and biochemical tests. For the bacterial replication, both SM1 and SM2 were actively multiplicated at pH 5.5. And the viability of SM1 was high at 20% of sucrose, while that of SM2 was high at 5% of sucrose in the media. SM1 actively replicated at 16mM of $CaCl_2$, 160mM of KCl, and 6.4mM of $MgCl_2$, and the replication of SM2 was increased at 16mM of $CaCl_2$, 40mM of KCl, 6.4mM of $MgCl_2$. At 1mM of sodium bicarbonate and sodium phosphate, both bacteria were actively multiplicated. SM1 and SM2 were actively replicated at 1mM and 10mM of Tris, respectively. For potassium phosphate buffer, SM1 grew well proportionally to the concentration up to 100mM, while the growth of SM2 were inhibited by the increase of concentration. The 4.6 kb of gtf gene was amplified with a pair of primer, gtfB-F961 and gtfC-R5574 by polymerase chain reaction from the chromosomal DNA of SM1 and SM2. When 4.6kb bands were eluted from gel and were treated with restriction enzyme, EcoR I produced the same RFLP like 0.8kb and 3.8kb of DNA fragments for S. mutans GS-5, SM1 and SM2. By Hind III, the PCR products weren't digested for S. mutans GS-5 and SM1, but 3 fragments such as 2.4kb, 1.8kb and 400bp were examined for SM2. These results indicated the difference between gtf genes of SM1 and SM2. BamH I treatment showed 4 fragments for SM1 and SM2, while the 3 fragments for S. mutans GS-5. The PCR products were not digested by Kpn I, Sma I, Xho I and Pst I.

• Journal of the Korean Society of Food Science and Nutrition
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• v.37 no.9
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• pp.1136-1141
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• 2008

This study was to investigate antiwrinkle effect of mugwort (Artemisia vulgaris) methanol extract in hairless mouse skin induced by UVB-irradiation. Hairless mouse were topically treated with the basic lotion alone (control), ascorbic acid (AA-0.5%, AA-1.0%, AA-2.0%, and AA-5.0%) and mugwort extract (ME-0.5%, ME-1.0%, ME-2.0%, and ME-5.0%) dissolved in a basic lotion. After topical treatment of 30 minutes, the animals were irradiated with increasing doses of UVB radiation ($60{\sim}100\;mJ/cm^2$) for 4 weeks. In our experimental condition, skin thickness of hairless mouse was significantly decreased ($12.5{\sim}21.4%$) in all ME groups compared with control group. Ra value, that is surface roughness parameter induced by skin wrinkling, was significantly decreased ($23.7{\sim}31.1%$) in ME-1.0%, 2.0% and 5.0% group compared with control group. Furthermore, Rq, Rz and Rt value were significantly decreased to $11.2{\sim}21.2%$, $19.8%{\sim}24.5%$, and $14.2%{\sim}22.7%$, respectively. Wrinkle formation of ascorbic acid treatment group as reference group was inhibited, but its effect was less than ME treatment. Matrix metalloproteinase-1 activity was significantly inhibited ($19.7{\sim}22.6%$) compared with control group and collagen content was significantly increased (about 10%) when compared with control group. These results indicate that ME could protect skin aging and wrinkle formation in hairless mouse from photo-irradiation.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.10 no.1
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• pp.31-37
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• 2005

To find out temporal variations of net photosynthetic rate (NPR) of intertidal flats, we measured oxygen microprofiles in sediments with oxygen microsensors 4 times from December 2003 to June 2004. The study areas were the intertidial flats in Janghwa-ri and Dongmak-ri, located on the southwestern and the southern parts of Ganghwa-gun, respectively, and in Incheon North Harbor where the content of organic matter was relatively high. During the investigation, oxygen penetration depths in the tidal flats of Janghwa-ri and Dongmak-ri were high in December (mean values of 4.0-4.1 mm). Thereafter, the oxygen penetration depths declined to mean values of 2.2-2.8 mm and 1.6-1.8 mm in the two tidal flats. Interestingly, the oxygen penetration depths in the Incheon North Harbor tidal flat showed a lower range $(0.8{\pm}0.3\;mm;\;mean{\pm}1SD)$ over the period. The maximum NPR in the Dongmak-ri tidal flat was found in March $(11.1{\pm}2.8\;mmol\;O_2\;m^{-2}\;h^{-1})$, and those In Janghwa-ri $(6.1{\pm}4.1\;mmol\;O_2\;m^{-2}\;h^{-1})$ and Incheon North Harbor $(6.4{\pm}1.4\;mmol\;O_2\;m^{-2}\;h^{-1})$ were observed in May. During the period when NPR was most active, the highest oxygen concentration was found at 0.1-0.5 mm depth below the surface sediment, and was on average 1.8-3.2 times higher than the air-saturated oxygen concentration in the overlying seawater. Although we took into account of low in situ light intensity $(400{\mu}Einst\;m^{-2}\;s^{-1})$ during the investigation in June, NPR in the 3 study areas decreased significantly to less than $0.2\;mmol\;O_2\;m^{-2}\;h^{-1})$. Thus, temporal variations of NPR were somewhat different among the tidal flats. Generally, benthic primary producers inhabiting in the uppermost 0.5 mm of the sediment showed a peak photosynthetic activity in the study areas in spring. This is the first domestic report on photosynthetic rates of benthic microflora in the tidal flats with oxygen microsensors, and the use of the microsensor can be widely applied to measurements of benthic primary production of a tidal flat and the oxygen consumption rate of surficial sediments.

• Korean journal of food and cookery science
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• v.11 no.1
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• pp.69-76
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• 1995

This study was concentrated on the subject of chou formation and physicochemical characteristics on medium flour mixed with 0, 25, 50, 75, 100% of rice flour in order to clarify the possibility to substitute rice flour for wheat flour on chou preparation. The water holding capacity, swelling power, and maximum viscosity were higher in rice flour than those in medium flour but the initial pasting temperature was equal to 65$^{\circ}C$ in the two flour groups. The ratio of setback during cooling became 0.94 in the rice flour and 1.14 in the medium flour. So, the rice flour showed a slow tendency during gel formation as compared with the medium flour. The volumes of the rice choux were ranged from 80.0% to 89.0% according to the mixing ratio of medium flour as compared with that of the chou of wheat flour. But, the choux formation were increased as much as 108.8% out the paste added gelation of glutinous substance and 124.4% at the paste added Span20 of emulsifier compared to the non-addition treatment. The paste of rice flour added gelatin and Span20 showed better dispersion of components, especially, the small granules of lipid were fairly or plentifully dispersed in the paste added Span20 due to emulsifying activity. In sensory evaluation, the chou of l00% rice flour was inferior to that of medium flour on cavity-forming but the choux of wheat flour mixed with 25%, 50%, and 75% of rice flour were equal or superior to that of medium flour on all characteristics tested such as appearance, surface color, cavity-forming, chewiness, and taste. There were no significant differences on the cavity-forming expansion and taste between choux of rice flour and wheat flour Therefore, the results of this study made conclusion that rice flour would be substituted for wheat flour on the chou preparation.

• Economic and Environmental Geology
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• v.49 no.2
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• pp.105-120
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• 2016

Most of riverside in Korea, in case of application of water curtain cultivation (WCC) technique, has been inveterately suffering from the gradual drawdown of groundwater level and related shortage of water resources during the WCC peak time. We believe that the water resources issue in these riverside areas can be effectively solved when the interaction between groundwater and nearby surface water is well understood. To investigate the connection between stream and ground water, and the influence of stream water on the nearby aquifer, this study examined the water temperature and oxygen and hydrogen stable isotopic compositions. The study area is well-known strawberry field applying the WCC technique in Sangdae-ri, Gadeok-myon, Cheongju City, and the sampling was done from February 2012 through June 2014 for stream and ground water. Some groundwater wells near stream showed big temporal variations in water temperature, and their oxygen and hydrogen stable isotopes showed similar compositions to those of adjacent stream water. This indicates that the influence of stream water is highly reflected in the stable isotopic composition of groundwater. Four cross-sectional lines from stream to hillside were established in the study area to determine the spatial differences in water quality of wells. At the late stage of WCC in February to March, groundwater of wells in line with short cross-sectional length showed the narrow range of isotopic compositions; however, those in the long cross-sectional line showed a wide compositional range. It was shown that the influence of the stream water at the late WCC stage have reached to the distance of 160 to 165 m from stream line, which is equivalent to the whole length and one-third point in each short and long cross-sectional line, respectively. Therefore, the wide compositional range in the long cross-sectional lines was not only due to the influence of stream water, but apparently resulted from the change of relative impact of each groundwater supplying from two or more aquifers. In view of stable isotopic compositions, there seems to be three different aquifers in this study area, which is competing for dominance of water quality in wells at each period of WCC.

• Radiation Oncology Journal
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• v.15 no.2
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• pp.97-104
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• 1997

of $PLC-\gamma$ 1 activity. Results : In the immunohistochemistry, the expression of $PLC-\beta$ was negative for all grnups. The expression of $PLC-\gamma$ 1 was highest in the group III followed by group II in the proliferative zone of mucosa. The expression of PKC-01 was strong1y positive in group I followed by group II in the damaged surface epithelium. The above findings were also confirmed in the immunoblotting study. In the irnrnunoblotting study, the expressions of $PLC-\beta,\;PLC-\gamma\;1,\;and\;PLC-\delta$ were the same as the results of immunohistochemistry The expression of ras oncoprotein was weakly Positive in groups II, III and IV. The of EGFR was the highest in the group II, III, followed by group W and the expression of PKC was weakly positive in the group II and III. Conclusion : $PLC-\gamma$ 1 mediated signal transduction including ras oncoprotein, EGFR, and PKC play a significant role irL mucosal regeneration after irradiation. $PLC-\delta$ 1 mediated signal transduction might have an important role in mucosal damage after irradiation. Further studies will be necessary to confirm the signal transduction mediating the $PLC-\delta$ 1.