• The Journal of the Korea Contents Association
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• v.14 no.12
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• pp.845-853
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• 2014

In this study, we measured the dose reaching the OSLD dosimeter by using the regular lead apron, and air gap apron through 3 experiments, and researched the reductive effect of air gap apron on exposure dose based on the 140 keV gamma ray radiating from $^{99m}technetium$, which is the most commonly used in nuclear medicine. As a result, when the gap between the dosimeter and 0.2mm lead plate is 0 Cm, the average value of 10 dosimeters was 0.515 mSv, and when the gap between the dosimeter and lead plate is 20 Cm, the average value of 10 dosimeters was 0.138 mSv, which shows reductive effect of dose as much as 0.388 mSv. When the gap between the dosimeter and 0.5mm lead plate is 0 Cm, the average value of 10 dosimeters was 0.296 mSv, and when the gap between the dosimeter and lead plate is 20 Cm, the average value of 10 dosimeters was 0.075 mSv, which shows reductive effect of dose as much as 0.221 mSv. As we check the cumulative dosage for 3 days, the lead apron without air layer shows average 0.239 mSv, and the air gap apron shows 0.176 mSv, which is actually reduced by 0.062 mSv. As we check the cumulative dosage for a month, the lead apron without air layer shows 0.59 mSv, and the air gap apron shows 0.54 mSv, which is reduced by 0.05 mSv.

• Journal of the Korean Chemical Society
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• v.20 no.3
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• pp.193-197
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• 1976

The ultrasonic absorption has been measured in aqueous solution of dodecyl pyridinium chloride (DPC) at $20^{\circ}C$ over the frequency range of 0.1${\sim}$90 Mc.The excess absorption was observed only in solutions in which the concentration was higher than the critical micellar concentration(cmc). The mechanism for this feature was attributed to the reaction $M_2\;{\rightleftharpoons}\;M_1\;＋\;1.2Cl^-$ Where $M_2$ and $M_1$ and M1 are two types of micelle. The rate constants of the forward and the reverse reactions were $6.6{\times}10^5 sec^{-1}\;and\;2.7{\times}10^11sec^{-1}mol^{-1.2}$respectively. Some kinetic charateristics including the free energy, enthalpy and entropy were calculated.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.10a
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• pp.283-285
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• 2013

피부의 관리를 위한 방법 중 광을 이용한 케어는 비침습적인 방법으로 세포를 활성화 시켜 도움을 주는 매우 유용한 방법이다. 최근에는 낮은 에너지의 LED를 광원으로 이용하는 LLLT (Low Level Light Therapy)가 많이 적용이 된다. 본 논문에서는 피부 미용기기에서 많이 사용되고 있는 가시광 영역의 적색과 황색, 그리고 적외선 영역의 LED를 이용하여 array를 제작하였다. 제작된 LED array는 5V의 전압과 50mA의 전류로 구동되며, 적색이 평균 $10.7mW/cm^2$, 황색이 평균 $1.8mW/cm^2$, 적외선이 평균 $5.5mW/cm^2$의 광출력을 갖는다. 이를 배양된 human cell plate에 각각 10, 20, 40분의 시간으로 조사하였으며, LED array와 조사면 사이에 20 mm의 거리를 두어 균일한 광량이 조사 될 수 있도록 하였다. 실험결과, wound healing의 경우는 적색광을 조사하였을 때, injury line의 길이가 $604.36{\mu}m$에서 10분 조사 시 $368.92{\mu}m$, 20분 조사 시 $298.04{\mu}m$, 40분 조사 시 $491.22{\mu}m$로 줄어드는 효과를 보였으며 특히 20분간 조사하였을 경우의 효과가 가장 좋았다. Cell regeneration의 경우는 황색광을 20분간 조사하였을 경우에 UV 에 의해 손상된 세포 수가 가장 크게 줄어드는 것을 확인할 수 있었다. 결과적으로 photorejuvenation 효과를 줄 수 있는 wound healing과 cell regeneration에는 적색 및 황색광의 LED array를 20분간 조사하였을 때가 가장 효과적이었으며, 적외광의 경우에는 모든 실험에서 효과가 없음을 확인할 수 있었다.

• The Korean Journal of Malacology
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• v.20 no.1
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• pp.17-26
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• 2004

In present study, attempts were made to preserve abalone (Haliotis discus hannai) sperm in liquid form at low temperature, to evaluate the effect of various diluents in short-term storage on sperm, and cryopreservation procedures were optimized for the cryoprotectants and freezing rates, as well as the motility, survival rate, and the ultrastructural changes of sperm after short-term storage and cryopreservation were observed. The abalone sperm reached maximum motility until about 4 min after activation. The motility was constant for about 16 min, after which it dropped gradually, and about 50 min later all motility ceased. In Hanks' balanced salt solution (HBSS, 300 and 400 mOsmol/kg) and 150, 250 and 350 mOsmol/k artificial seawater (ASW), the sperm was immotile. After 100% ASW was added, motility of those sperm, which are in 300, 400 mOsmol/kg HBSS, 250, 350 mOsmol/kg ASW, could be again restored incompletely. Sperm motility can be maintained for 20 days of cold storage only in ASW of 850 and 1200 mOsmol/kg. A high motility index of 3.5-4.5 was observed for the first 8 days in 850 and 950 mOsmol/kg ASW. In other diluents sperm motility was constant less than 10 days, and the motility index was obviously lower than that of sperm in 850 and 1200 mOsmol/kg ASW. After 20 days of cold storage, survival rates of 10.2%-20.7% were obtained in ASW and 300 mOsmol/kg HBSS, and that in 400 HBSS (65.3%) was significantly higher than others. The constant period of sperm motility stored in 850 mOsmol/kg ASW was obviously longer than that in 1200 mOsmol/kg ASW after 6 days of storage. The sperm plunged into liquid nitrogen all died except that sperm using 15% glycerol as cryoprotectant restored 10.4% of motility. The highest motility index (3.4) was obtained with 5% glycerol and freezing procedure: $-50^{\circ}C$/min from $20^{\circ}C$ to $-80^{\circ}C$.

• Microbiology and Biotechnology Letters
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• v.30 no.4
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• pp.373-379
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• 2002

By using DL-acetonitrile as enzyme inducer, 90 bacteria were isolated from a field soil. Among the isolated strains, the strain WJ-003 showed the highest activity for production of D-lactic acid from DL-lactonitrile, and was partially identified as Pseudomonas sp. The production condition of D-lactic acid from DL-lactonitrile using resting cells as an enzyme source was optimized as follows: the reaction mixture contained 10 mM of DL-lactonitrile, 20 g of wet cells in 11 of 20 mM potassium phosphate buffer (pH 7.0) and the reaction was carried out at $30^{\circ}C$. After 18 h of reaction, 0.843 g/l of D-lactic acid was produced which corresponded to a conversion ratio of 93.7% and an optical purity of 99.8%. Additionally, when 10 mM of DL-lactonitrile was added once more to the reaction mixture at 14 h, 1.64 g/1 of D-lactic acid was produced after 28 h. In this experiment, the conversion ratio was 91.1% and optical purity 99.8%.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.11
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• pp.5206-5210
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• 2012

We studied the effect of food concentration on grazing, growth and fecundity of cyclopoid copepod Paracyclopina nana. Marine phytoplankton Tetraselmis suecica was used as a livefood for the copepod. Six stage compositions were used and food concentrations for the experiment were 0.5, 1, 2, 5, 10, 20, 40, 60 and $80{\times}10^4$ cells/mL. Range of food concentrations with 0.2, 0.5, 1, 2, 3 and $4{\times}10^4$ cells/mL were used for nauplii production experiment. Grazing rates of P. nana in all developmental stages on the different concentrations were increased with increasing diet concentration. While the growth of nauplius was not affected by increase of food concentration, food concentration outside of $1{\times}10^4$ to $5{\times}10^4$ cells/mL range negatively affected that of copepodite. Daily nauplii production was increased with increasing food concentration but $3{\times}10^4$ and $4{\times}10^4$ cells/mL treatments were not significantly different with $2{\times}10^4$ cells/mL treatment. As a result, optimum concentration of T. suecica for mass culture of P. nana was considered to be 5,000 cells/mL for nauplius stage, 10,000 cells/mL for copepodite stage and adult male, 20,000 cells/mL for adult female, respectively.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.43 no.3
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• pp.231-238
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• 2010

The Induction of regeneration and maturation in the free-living gametophytes of Ecklonia stolonifera Okamura was studied at four temperatures (5, 10, 15, and $20^{\circ}C$), four levels of irradiance (5, 10, 20, and 40 ${\mu}mol\;m^{-2}s^{-1}$) and three photoperiods (14:10, 12:12, and 10:14 h L:D). Female gametophyte fragments were maintained in active regeneration without reaching sexual maturity under $5{\sim}10^{\circ}C$, 10 ${\mu}mol\;m^{-2}s^{-1}$, 10:14 h (L:D), whereas the conditions for male gametophytes were slightly different at $20^{\circ}C$, 40 ${\mu}mol\;m^{-2}s^{-1}$, 10:14 h (L:D). The sexual maturation of female and male gametophytes was facilitated at $15^{\circ}C$, 20 ${\mu}mol\;m^{-2}s^{-1}$, 14:10 h (L:D). These results provide basic information for controlling the regeneration and maturation of the free-living gametophytes for artificial seed production of E. stolonifera.

• Reproductive and Developmental Biology
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• v.35 no.3
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• pp.295-300
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• 2011

The objective of this study was to evaluate efficiency of methyl-beta-cyclodextrin (MBCD) in the sperm preservation of bull. For this study, the freezing of diluted semen were added with Triladyl containing 20% egg-yolk and/or 0, 1, 5, 10 and 20 mM MBCD before freezing process. Analysis of viability in frozen-thawed sperm was estimated by SYBR14/PI double stain, hypoosmotic swelling test(HOST) and acrosome damage with FITC-PNA, and mitochondria activation with Rhodamin123 by flow-cytometry. The sperm viability was significantly in 0 mM and 5 mM concentrations of MBCD than other groups (p<0.05). However, the HOST was significantly lower at 20 mM concentration of MBCD than other concentrations (p<0.05). In addition, acrosome damage and mitochondria activation rates were significantly lower at 20 mM concentration of MBCD than other groups (p<0.05). In conclusion, the viability of sperm was not significantly different among concentrations of MBCD 0, 5 and 10 mM, but MBCD 20 mM was significantly lower than other groups. In addition, as concentrations of MBCD was high, HOST, acrosome damage and mitochondria activation rates had a negative effect in bull sperm.

• The Korean Journal of Nuclear Medicine Technology
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• v.14 no.1
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• pp.24-27
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• 2010

Purpose: Early diagnosis of breast is of the utmost importance to improve prognosis. We have a limitation for mammography and sonography detecting small cancer. Clinical importance of Breast Specific Gamma Imaging (BSGI) has improved for that reason. So We studied performance evaluation test of count rate and resolution with high sensitivity to the low dose of BSGI. Materials and Methods: BSGI of Dilon 6800, point source of $^{99m}Tc$ from 1.85~148 MBq (0.05~4 mCi) at the intervals of 1.85~37 MBq (0.05~1 mCi) was used for the test. Performance evaluation method was performed for measuring deadtime for choosing at the 5 different point in the useful field of view (UFOV), acquired image for 60 seconds. Compared with reference of clinical uptake distribution of breast, activity increased according to the distance change 10, 20, 30, 40, 50 mm in the useful field of view. Results: Counting curve increased according to the activity from 1.85 MBq (0.05 mCi) to the 74 MBq (2 mCi), and it change flat shape over 74 MBq (2 mCi). The variation of the full width of half maximum (FWHM) to the distance is 4.05, 4.73, 5.77, 6.90, 8.00, 9.32 mm in 1.85 MBq (0.05 mCi), 4.30, 4.80, 5.90, 7.00, 8.10, 9.07 mm in 3.7 MBq (0.1 mCi), 4.90, 5.60, 6.20, 7.20, 8.20, 9.10 mm in 5.55 MBq (0.15 mCi), 5.30, 6.10, 6.60, 7.00, 7.90, 8.70 mm in 7.40 MBq (0.2 mCi). Conclusion: Distortions of image would be acquired because of the deadtime in BSGI. We found out the fact that specification of $^{99m}Tc$ reaction under 74 MBq (2 mCi) for BSGI. Second, FWHM distribution change from varied distance from the detector, clearly distinguished the location of the lesion.

• KSBB Journal
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• v.25 no.3
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• pp.265-270
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• 2010

Simvastatins are widely used to reduce endogenous cholesterol synthesis and improve hypercholesterolemia. Also, simvastatin have been shown to induce both angiogenic and angiostatic responses. In this study, It was attempted to resolve this controversy by studying the effects of simvastatin on the cell migration and invasion with the proteinases secretion and expression pattern. U-373-MG cells treated with low dose of simvastatin ($0.001{\sim}0.5\;{\mu}M$) showed the induction of migration and invasion compared with the addition of a control buffer. On the contrary, high dose of simvastatin ($1{\sim}20\;{\mu}M$) showed the reduction of migration and invasion compared with the addition of a control buffer. It was also showed that simvastatin-regulated migrative and invasive phenotypes were consistent with the secretion and expression pattern of matrix metalloproteinase-2 (MMP-2), MMP-9 and plasmin.