• 한국가축번식학회지
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• 제16권4호
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• pp.353-361
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• 1993

This study was taken to examine external changes, behavioral changes, and endocrine changes such as estradiol-17$\beta$, progesterone, T4 and T3 of female Oreochromis niloticus living in 0$\textperthousand$, 10$\textperthousand$, 20$\textperthousand$, and 30$\textperthousand$ salt concentrations, respectively. The results obtained in these experiments were summarized as follows. In seawater obtained in these experiments were summarized as follows. In seawater challenge test, any fish didn't die in each group such as 10$\textperthousand$, 20$\textperthousand$ and 30$\textperthousand$. When fish were adapted from 0$\textperthousand$ to 10$\textperthousand$, 20$\textperthousand$ and 30$\textperthousand$, external body color of fish changed from dark-striped to light-grey color. At the same time, thyroxine and triiodothyronine concentrations significantly(P<0.05) increased, and then were at the highest level in 30 salinity. When fish were adapted from 0$\textperthousand$ to 10$\textperthousand$, feed intake of fish started from the fourth day. From 0$\textperthousand$ to 10$\textperthousand$, 20$\textperthousand$ and 30$\textperthousand$, estradiol-17$\beta$ levels were increased gradually. When fish was adapted from 0$\textperthousand$ to 10$\textperthousand$, 20$\textperthousand$ and 30$\textperthousand$, the levels of each progesterone didn't show significant change, and especially showed the lowest peak in 20$\textperthousand$. The greatest thyroxine activity(T4) was observed in 30$\textperthousand$. The levels of and triiodothyronine(T3) significantly changed in all salinities, and its level was at the highest peak in 30$\textperthousand$ salinity. Correlation coefficients between serum progesterone and triiodothyronine in 10$\textperthousand$ and 30$\textperthousand$ were ＋0.677 and ＋0.843, respectively. Correlation coefficient of serum thyroxine(T4) and triiodothyronine(T3) individuals in 10$\textperthousand$ was ＋0.768, and ＋0.843, respectively.

• Asian-Australasian Journal of Animal Sciences
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• 제5권1호
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• pp.101-106
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• 1992

Secretory patterns of serum tri-iodothyronine, thyroxin and testosterone were analysed by specific radioimmunoassay in Kaghani (n = 42), Rambouilet (n = 42) and Kaghani ${\times}$ Rambouillet (n = 42) male sheep to determine age and breed related changes. Animals were examined at 1-2 wk, 8, 10, 12, 20, 22 and 24 months of age (n = 6/age group). All animals were maintained under standard conditions of feeding and management. $T_3$ and $T_4$ concentrations were maximal (p < 0.01) in 1-2 wk old lambs of all breeds studied ($207.4{\pm}14.9-276.8{\pm}20.4ng/dl$ and $5.76{\pm}0.3-7.23{\pm}0.9{\mu}g/dl$, respectively). For all the breeds, concentrations of $T_3$ declined markedly (p < 0.01) at 8 month of age and then varied in a narrow range ($44.5{\pm}14.0-87.0{\pm}4.8ng/dl$) up to the age of 24 month. While, serum $T_4$ concentrations decreased (p < 0.01) to nadir ($0.97{\pm}0.1-1.43{\pm}0.3{\mu}g/dl$) at 10 months of age in all the 3 breeds. Afterwards, $T_4$ levels increased gradually and attained a small peak at 20 months before declining again at 22 and 24 months of age. Serum $T_3$ and $T_4$ concentrations were correlated significantly (p < 0.05) and their ratio was constant at all ages in the different breeds. Age significantly (p < 0.01) influenced the secretion of testosterone in the breeds examined but the breed differences were comparable. Mean serum concentrations of testosterone were low from 1-2 wk to 10 months of age in the Kaghani, Rambouillet and Kaghani ${\times}$ Rambouillet animals. Peak testosterone levels were noted in the 12 months old Kaghani ($1.75{\pm}0.4ng/ml$), Rambouillet ($1.30{\pm}0.2ng/ml$) and their $T_3$ cross animals ($1.16{\pm}0.08ng/ml$). Mean testosterone levels, thereafter, decreased at 20 months and then at 22 and 24 months remained variable but higher than observed at 1-2 wk -10 months of age. The findings of the present study indicate a significant influence of age but not of breed on the peripheral concentrations of thyroid hormones and testosterone. Serum concentrations of $T_3$ and $T_4$ were not related to testosterone levels. High thyroid secretory activity observed at prenatal phase of development may play an important role in preparing the lambs to extrauterine environments.

• 한국미생물·생명공학회지
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• 제16권2호
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• pp.136-141
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• 1988

고온 발효성인 Saccharomyces cerevisiae D-71과 내삼투압성인 Zygosaccharomyces rouxii SR-S를 여러 조건에서 배양하여 Zymolyase-20T에 대한 감수성을 조사하였다. Sacch. cerevisiae D-71의 glucan과 mannan 함량은 각각 l4.5%와 14.8% 이었고 Zygosacch. rouxii SR-S는 24.0%와 19.0% 이었다. 0.5% methionine 과 0,1% glucose를 함유한 wickerham 합성배지에 Sacch. cerevisiae D-71를 배양하여 얻은 세포의 Zymolyase-20T에 대한 감수성은 66% 이었고 $K_2$HPO$_4$와 aminobenzoic acid를 결핍시켰을 때 감수성이 가장 낮았다. 또한 0.5% peptone과 o.15% methionine 및 0.1% glucose를 함유한 wickerham 합성배지에 Zygosacch. rouxii SR-S를 배양하여 얻은 세포의 감수성은 80% 이었고 KI와 pyridoxine을 결핍시켰을 때 감수성이 가장 낮았다. $25^{\circ}C$에서 YMPG 배지에 Sacch. cerevisiae D-71를 접종하여 12시간 정치배양한 세포의 Zymolyase-20T에 대한 감수성은 76% 이었고 Zygosacch. reuxii SR-S를 같은 조건으로 30시간 배양한 세포의 감수성은 82%로서 wickerham 합성배지에서의 감수성보다 더 좋았다.

• 한국발생생물학회지:발생과생식
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• 제15권3호
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• pp.223-230
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• 2011

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental contaminants derived from incomplete combustion of carbons and crude oil. In this study, we investigated the effects of benzo[a]pyrene (B[a]P), a representative PAHs on in vitro sex steroid hormone production and germinal vesicle breakdown (GVBD) using isolated oocytes of longchin goby (Chasmichthys dolichognathus) and chameleon goby (Tridentiger trigonocephalus). Oocytes in diameters of 0.8-0.9 (end vitellogenic stage) and 0.9-1.0 mm (germinal vesicle migratory stage) from longchin goby and 0.5 mm (fully vitellogenic stage) from chameleon goby were used. In GVBD assay, B[a]P at 10 nM stimulated GVBD in the oocytes of 0.8-0.9 mm from longchin goby. B[a]P at 1 nM stimulated GVBD in the oocytes with diameter 0.5 mm from chameleon goby. In steroid production from oocytes of longchin goby, B[a]P at 100 nM decreased testosterone (T) production, B[a]P at 1,000 nM increased estraiol-17 (J (E2) production and 10 and 100 nM increased $17,20{\beta}$-dihydroxy-4-pregnen-3-one ($17{\alpha}20{\beta}P$) production in the oocytes with diameter 0.8-0.9 mm. B[a]P at 1,000 nM increased E2 production, 100 and 1,000 nM increased $17{\alpha}20{\beta}P$ production in the oocytes with diameter 0.9-1.0 mm. In steroid production of oocytes from chameleon goby, B[a]P at 1,000 nM increased $E_2$ production. B[a]P at 10 nM increased $17{\alpha}20{\beta}P$ production. In the ratio of $E_2$ to T ($E_2$/T), B[a]P at 100 and 1,000 nM increased $E_2$/T in the oocytes of longchin goby. B[a]P at 100 nM also increased $E_2$/T in the oocytes of chameleon goby. Taken together, these results suggest that B[a]P have not only weak estrogenic effects but progestogenic effects on oocyte maturation.

• 한국분말재료학회지
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• 제16권5호
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• pp.358-362
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• 2009

Ti$_{50}$Cu$_{20}$Ni$_{20}$Al$_{10}$ quaternary amorphous alloy was prepared by high-energy ball milling process. A complete amorphization was confirmed for the composition of Ti$_{50}$Cu$_{20}$Ni$_{20}$Al$_{10}$ after milling for 30hrs. Differential scanning calorimetry showed a large super-cooled liquid region ($\Delta$T$_x$ = T$_x$ T$_g$, T$_g$ and T$_x$: glass transition and crystallization onset temperatures, respectively) of 80 K. Prepared amorphous powders of Ti$_{50}$Cu$_{20}$Ni$_{20}$Al$_{10}$ were consolidated by spark-plasma sintering. Densification behavior and microstructure changes were investigated. Samples sintered at higher temperature of 713 K had a nearly full density. With increasing the sintering temperature, the compressive strength increased to fracture strength of 756 MPa in the case of sintering at 733 K, which showed a 'transparticle' fracture. The samples sintered at above 693 K showed the elongation maximum above 2%.

• Journal of electromagnetic engineering and science
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• 제15권3호
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• pp.142-150
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• 2015

Several reports supported that continuous exposure to 60 Hz magnetic field (MF) induces testicular germ cell apoptosis in vivo. We recently evaluated duration- and dose-dependent effects of continuous exposure to a 60 Hz MF on the testes in mice. BALB/c male mice were exposed to a 60 Hz MF at $100{\mu}T$ for 24 hours a day for 2, 4, 6, or 8 weeks, and at 2, 20 or $200{\mu}T$ for 24 hours a day for 8 weeks. To induce the apoptosis of testicular germ cell in mice, the minimum dose is $20{\mu}T$ at continuous exposure to a 60 Hz MF for 8 weeks, and the minimum duration is 6 weeks at continuous exposure of $100{\mu}T$. Continuous exposure to a 60 Hz MF might affect duration- and dose-dependent biological processes including apoptotic cell death and spermatogenesis in the male reproductive system of mice. The safety guideline of the International Commission on Non-Ionizing Radiation Protection (ICNIRP) indicates that the permissible maximum magnetic flux density for general public exposure is $200{\mu}T$ at 60 Hz EMF (ICNIRP Guidelines, 2010). In the present study, we aimed to examine the expression of pro- and anti-apoptotic genes regulated by the continuous exposure to 60 Hz at $200{\mu}T$ in Sprague-Dawley rats for 20 weeks. The continuous exposure to 60 Hz at $200{\mu}T$ does not affect the body and testicular weight in rats. However, exposure to 60 Hz MF significantly affects testicular germ cell apoptosis and sperm count. Further, the apoptosis-related gene was scrutinized after exposure to 60 Hz at $200{\mu}T$ for 20 weeks. We found that the message level of endonuclease G (EndoG) was greatly increased following the exposure to 60 Hz at $200{\mu}T$ compared with sham control. These data suggested that 60 Hz magnetic field induced testicular germ cell apoptosis through mitochondrial protein Endo G.

• 수산해양기술연구
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• 제37권4호
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• pp.275-284
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• 2001

본 연구에서는 제주대학교 실습선 아라호(G/T : 990tons)의 조종 성능을 파악하기 위하여 2000년 8월과 2001년 5월에 2회에 걸쳐 제주항 북방 3마일 해상에서 조타에 의한 선회성과 추종성 등의 조종성능을 실시한 결과는 다음과 같다. 1. 부표 방위반법으로 측정한 선회권의 크기에서 선회종거는 우현선회시가 198m, 좌현선회시가 192m로서 좌현선회시가 우현선회시보다 6m 작았으며, 또한, 선회경의 크기는 우현선회시가 194m, 좌현선회시가 188m로서 좌현선회시가 우현선회시 보다 6m 작았다. 2. DGPS 측위에 의한 선회권의 크기에서 선회종거는 우현선회시가 196m, 좌현선회시가 194m로서 좌현선회시가 우현선회시보다 2m 작았다. 또한, 선회경의 크기는 우현선회시가 194m, 좌현선회시 190m로서 좌현선회시가 우현선회시보다 4m 작았다. 3. 신조 시운전시 부표 방위반법에 의해 측정한 선회권의 크기와 2001년 5월에 DGPS 측위에 의하여 측정한 선회권의 크기를 비교해 본 결과, 선회종거는 DGPS 측위에 의한 선회권이 신조시운전시 선회종거보다 우현선회시가 1m 컸으며, 좌현선회시가 21m 작았다. 또한, 선회경의 크기는 우현선회시 16m, 좌현선회시 23m 작았다. 4. 선속 13k't로 전속 전진중 타각 $35^\circ$로 좌현 또는 우현으로 전타 했을 때 선회각 $180^\circ$에서 선속이 7.8k't이고 $360^\circ$선회시는 6.0k't가 되었으며, 소요 시간은 좌현선회시가 150초, 우현선회시가 156sec로 좌현선회시가 우현선회시보다 6초 짧았으며, 선회평균 각속도는 좌현선회시가 $2.4^\circ$/sec, 우현선회시가 $2.3^\circ$/sec였다. 5. 타각 $10^\circ$, $20^\circ$, $30^\circ$ Z시험에서 선회성지수 K와 추종성지수 T는 각 각 선회성지수는 1.24, 1.45, 1.65였으며, 추종성지수는 각 각 0.33, 0.20, 0.14가 되어 $30^\circ$인 경우가 $10^\circ$, $20^\circ$ Z시험에서 보다 선회성지수 K는 크고, 추종성지수 T는 작아서 대각도 조타일 때가 소각도 조타일 때 보다 조종성능이 양호하였다.

• 통합자연과학논문집
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• 제14권3호
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• pp.123-129
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• 2021

This research examines the effect of positively skewed population distribution on the two sample t-test through simulation. For simulation work, two independent samples were selected from the same chi-square distributions with 3, 5, 10, 15, 20, 30 degrees of freedom and sample sizes 3, 5, 10, 15, 20, 30, respectively. Chi-square distribution is largely skewed to the right at small degrees of freedom and getting symmetric as the degrees of freedom increase. Simulation results show that the sampled populations are distributed positively skewed like chi-square distribution with small degrees of freedom, the F-test for the equality of variances shows poor performances even at the relatively large degrees of freedom and sample sizes like 30 for both, and so it is recommended to avoid using F-test. When two population variances are equal, the skewness of population distribution does not affect on the t-test in terms of the confidence level. However even though for the highly positively skewed distribution and small sample sizes like three or five the t-test achieved the nominal confidence level, the error limits are very large at small sample size. Therefore, if the sampled population is expected to be highly skewed to the right, it will be recommended to use relatively large sample size, at least 20.

• 한국운동역학회지
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• 제32권4호
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• pp.121-127
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• 2022

Objective: The purpose of this study was to investigate potential effects of transcranial direct current stimulation (tDCS) on bimanual force control capabilities in healthy young adults. Method: Eighteen right-handed healthy young adults (10 females and 8 males; age: 23.55 ± 3.56 yrs) participated in this crossover design study. All participants were randomly allocated to both active-tDCS and sham-tDCS conditions, respectively. While receiving 20 min of active- or sham-tDCS interventions, all participants performed bimanual isometric force control tasks at four submaximal targeted force levels (i.e., 5%, 10%, 15, and 20% of maximal voluntary contraction: MVC). To compare bimanual force control capabilities including force accuracy, variability, and regularity between active-tDCS and sham-tDCS conditions, we conducted two-way repeated measures ANOVAs (2 × 4; tDCS condition × Force levels). Results: We found no significant difference in baseline MVC between active-tDCS and sham-tDCS conditions. Moreover, our findings revealed that providing bilateral tDCS including anodal tDCS on left primary motor cortex (M1) and cathodal on right M1 while conducting bimanual force control trials significantly decreased force variability and regularity at 5%MVC. Conclusion: These findings suggest that providing bilateral tDCS on M1 areas may improve bimanual force control capabilities at a relatively low targeted force level.

• Mycobiology
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• 제37권1호
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• pp.10-16
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• 2009

The purpose of this study is to understand spatio-temporal changes of active fungal biomass and water in Tricholoma matsutake soil colonies during the mushroom fruiting season. The active fungal biomass was estimated by analyzing ergosterol content at four different points within four replicated locations in a single circular T. matsutake colony at Ssanggok valley in the Sogri Mt. National Park in Korea during 2003 to 2005. The four points were the ahead of the colony, the front edge of the colony and 20 cm and 40 cm back from the front edge of the colony. Ergosterol content was 0.0 to 0.7 ${\mu}g$ per gram dried soil at the ahead, 2.5 to 4.8 ${\mu}g$ at the front edge, 0.5 to 1.8 ${\mu}g$ at the 20 cm back and 0.3 to 0.8 ${\mu}g$ at the 40 cm back. The ergosterol content was very high at the front edge where the T. matsutake hyphae were most active. However, ergosterol content did not significantly change during the fruiting season, September to October. Soil water contents were lower at the front edge and 20 cm back from the front edge of the colony than at the ahead and 40 cm back during the fruiting season. Soil water content ranged from 12 to 19% at the ahead, 10 to 11% at the edge, 9 to 11% at the 20 cm back and 11 to 15% at the 40 cm back. Our results suggest that the active front edge of the T. matsutake soil colony could be managed in terms of water relation and T. matsutake ectomycorrhizal root development.