• Development and Reproduction
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• v.12 no.1
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• pp.57-66
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• 2008

Changes in luteinizing hormone (LH), serum testosterone (T), and salivary T levels with age were examined in Korean men. Serum was obtained from 167 Korean men of different ages ($20{\sim}69\;y$), and the serum LH and T levels were measured. Saliva samples were also obtained, and the salivary T level was determined. The LH levels did not change considerably until 40 y of age (20s, $2.5{\pm}1.0$; 30s, $2.7{\pm}1.5$; and 40s, $2.5{\pm}1.8\;mIU/mL$) but increased significantly around 50 y (50s, $3.7{\pm}1.8$ and 60s, $3.1{\pm}1.7\;mIU/mL$). Further, the serum T levels also did not change until 40 y of age (20s, $5.3{\pm}2.6$, 30s, $4.4{\pm}1.4$, 40s, $4.1{\pm}1.5\;ng/mL$) but decreased significantly at 50 y (50s, $3.4{\pm}1.5$; 60s, $2.6{\pm}0.8\;ng/mL$). The salivary T levels also showed small changes until the age of 40 y ($20s{\sim}40s$, $0.11{\pm}0.015\;ng/mL$) but decreased significantly at 50 y ($0.08{\pm}0.03\;ng/mL$). Thus, the relative ratio of salivary T to serum T levels did not change significantly in all the ages examined ($2.4{\pm}0.9%$). Linear regression analysis predicted that the LH levels increased 1.5%/y while the serum and salivary T levels decreased 1%/y and 0.8%/y, respectively. The serum T/LH ratio did not change considerably until the age of 40 y ($20s{\sim}40s$, $2.27{\pm}0.14$) but decreased significantly ($1.2{\pm}1.0$) at 50 y. Age-related changes in the salivary T/LH ratio were very similar to those in the serum T/LH ratio. These results demonstrated that LH and T levels in serum or saliva did not change considerably until 40 y of age; instead, in Korean men, from 50 y of age, the LH level increased, while the T level decreased. This suggests that primary testicular failure that occurred due to aging (approximately 50 y) and caused this phenomenon. The present study also shows that the salivary T level can be an indicator of the free T level in serum although the salivary T level correlates weakly with the total T level in serum (r=0.53). Thus, information regarding salivary T levels may be useful for studying the age-related changes occurring in male testicular physiology.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.18 no.2
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• pp.77-80
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• 1982

The maneuverabilities of 240 GT class skipjack pole and liner were studied, based on the maneuvering indices and the data which were obtained from Z test of the experimental ship, the m.s. KWANACKSAN, the training ship of the National Fisheries University of Busan. The maneuvering indices K' of the experimental ship were 0.611(at 10$^{\circ}$Z test), 0.622(at 20$^{\circ}$Z test) and 0.556(at 30$^{\circ}$Z test). Her maneuvering indices T' were 1.094(at 10$^{\circ}$Z test), 1.695(at 20$^{\circ}$Z test) and 1.367(at 30$^{\circ}$Z test). The above calculated values K', T' showed that her turning ability at helm angle 20$^{\circ}$ and her obeying ability at helm angle 10$^{\circ}$ were most effective. As it appeared that the calculated K'-values of the experimental ship were smaller than the standard K'-values of different kinds of ships and her overshoot angles at her Z test were greater than those of them, her turning ability was found to be lower. When the experimental ship took a turn at her 10$^{\circ}$Z test, running distance was about 8.3 times her own length and didn't exceed the standard maneuvering distance, 5 to 11 times ship's own length, therefore she was considered to have good maneuverabilities synthetically.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.7
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• pp.613-624
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• 2002

Electrical characteristics of two types of 20 GHz Push-Push GaAs MESFET dielectric resonator oscillators having Wilkinson and T-junction power combiners for the output stage have been investigated and compared. So we have explained that the output power and phase noise properties of the Push-push FET DRO are depending on return loss and isolation characteristics of power combiner at the fundamental and the second harmonic frequencies. A Push-push oscillator for suppressing the fundamental frequency of 10 GHz and enhancing the second harmonic of 20 GHz has been designed and fabricated in microstrip configuration on 20 mil thick RT-Duroid($\varepsilon$$_{r}$ = 2.52) Teflon substrate. Return loss and isolation characteristics of T-junction and Wilkinson have been measured at the fundamental frequency of 10.2 GHz and the second harmonic frequency of 20.5 GHz. At the fundamental frequency, -12 dB return loss and -3.7 dB isolation have been measured for the T-junction power combiner, and -14 dB return loss and -11 dB isolation fur the Wilkinson power combiner. At the second harmonic frequency, -10 dB return loss and -7.5 dB isolation have been obtained for the T-junction power combiner, and -23 dB return loss and -22 dB isolation for the Wilkinson power combiner. As a result, we have confirmed that the oscillator based on the Wilkinson power combiner with better retrun loss and isolation characteristics produces more output power and better phase noise characteristics..

• Korean Journal of Poultry Science
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• v.30 no.4
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• pp.229-233
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• 2003

A study was conducted to investigate the effects of different BW control methods during rearing on laying performance of broiler breeder pullets. D-old 540 female breeder chicks (Arbor Acres) were assigned to three treatments consisted of standard BW (Control), 110% of standard BW at 12 wk of age (T1), and 90% of standard BW at 12 wk of age (T2), with three replicates of 60 birds per replicate (pen) for each treatment. At 20 wk of age, all birds from three treatments reached the BW reqired in the Arbor Acres Manual. There were no significant differences in egg production, egg weight and viability during laying period(p>0.05). However, total egg production rates were improved in T2 and T3. Average egg weight was the highest in T1 among all treatments. Fertility and hatchability were similar among treatments, but T2 tended to be higher than other treatments at 37 and 53 wk of age. No significant difference was found in hatchability among three treatments. The number of hatching egg of T2 reached 168 per year, showing higher number of eggs than did the other treatments. The number of hatched chicks in T2 was 131, which was also higher than the other treatments, but the difference was not significant. It appears that the laying performance of broiler breeder hens could be improved when their BW at 12 wk of age are kept at 90% of standard BW, and reach the standard BW at 20 week of age.

• Journal of Animal Science and Technology
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• v.51 no.1
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• pp.61-68
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• 2009

The effects of hot-air dried tomato powder (HADTP) with 0% (C), 0.25 (T1), 0.50 (T2), 0.75 (T3) and 1.00% (T4) addition to the pork patties on the physicochemical and sensory properties during storage at $-20^{\circ}C$ for 20 days were studied. Cooking loss, thiobarbituric acid reactive substances (TBARS), volatile basic nitrogen (VBN) and CIE $L^*$ values of all products were increased (p<0.05) significantly as the storage period increased, while the pH values were decreased (p<0.05). The CIE $a^*$ and $b^*$value of all samples showed a tendency of decreasing value through the storage days. The pH and cooking loss of T4 were significantly lower (p<0.05) than those of other treatments. The TBARS values of treatments were significantly lower (p<0.05) compared to those of control, but CIE $a^*$ and $b^*$ values of treatments were higher (p<0.05) than those of control at day 20 of storage. VBN values of treatments were significantly lower (p<0.05) than those of control at day 20 of storage. In the sensory evaluation, color and overall acceptability in T3 and T4 were higher (p<0.05) than the others until 15 days of storage. In conclusion, pork patties with 0.75~1.00% HADTP had a higher acceptability, redness and lipid oxidative stability during freeze storage than products without HADTP.

• Geotechnical Engineering
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• v.6 no.1
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• pp.7-14
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• 1990

The two degree of freedom model is proposed to study the effects of imperfect fixing at the active end of spring-top resonant column apparatus. A computer program using the SYMPHONY spreadsheet is developed to calculate the dimensionless frequency, F, from which modulug can be determined. It is found that the effect of reaction mass through the parameter Tr on dimensionless frequency, F, can not be ignored if Tr$\leq$20. As To increases, the variation of F increases. But for Tr$\geq$ 20, the effect of To becomes small. It is recommended that T. be greater than 20 if single degree of freedom model is rosed to determine modulus of soil. It also is found that damping ratios of specimen and apparatus do not strongly affect the dimensionless frequency, F.

• Journal of Advanced Navigation Technology
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• v.6 no.1
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• pp.52-62
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• 2002

Electrical characteristics of two types of 20 GHz Push-Push GaAs MESFET dielectric resonator oscillators having Wilkinson and T-junction power combiners for the output stage have been investigated. The Push-Push oscillator for suppressing fundamental frequency 10 GHz and enhancing 20 GHz has been designed and realized in microstrip configuration on 20 mil thick RT-Duroid(${\varepsilon}_r$=2.52) teflon substrate. Two different types of power combiners, T-junction and Wilkinson, have been considered. Whenever one type of the combiners has been adopted for the output circuit, output power, phase noise and fundamental frequency suppression characteristics of the oscillator have been measured. When the Wilkinson power combiner was used, a maximum output power of 5.67 dBm, a phase noise of -105.5 dBc/Hz at an offset frequency of 100 kHz and a fundamental frequency suppression of -29.33 dBc have been measured. When the T-junction power combiner was used, a maximum output power of -1.17 dBm, a phase noise of -102.2 dBc/Hz at an offset frequency of 100 kHz and a fundamental frequency suppression of -17.84 dBc have been measured.

• Asian Journal of Turfgrass Science
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• v.8 no.1
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• pp.1-11
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• 1994

Studies were conducted to evaluate the effect of priming and preimbibition on gerraination of unscarified and KOH-scarified zoysiagrass (Zoysia japonica Steud.) seeds, respectively. Germi-nation percentages at 35˚C of seeds primed in $KNO_3$ and Ca($NO_3$)$_2$ were significantly higher than that of untreated seeds. The optimum conditions for priming unscarified seeds were in aerated $KNO_3$ solution at O4 M for 4 days at 20˚C. No additional benefit of $GA_3$ on increasing germination was not found in seed priming with solution of $KNO_3$ + $GA_3$ or in seeds preimbibed with $GA_3$ after priming. Scarified seeds preimbibed with distilled water(DW) for 4 days at 20˚C germinated higher and with fewer days to 50% of total germination(T 50) than untreated seeds. Preimbibition with $GA_3$ solution at 50 ppm for 4 days at 5, 10, 15 and 20˚C enabled up to 97% of seeds to germinate and reduced days to T 50 about 1.1 to 1.2 days at 35˚C Especially, seeds preimbibed with $GA^2$˚$_3_2_1$$\times$ had greatly higher germination and lower T 50 than untreated or DW-preimbibibed seeds at 30˚C, which is inadequate to germination in general. Preimbibed seed performance was unchanged after storage at room temperature for 50 days. Seeds preimbibed with GA $_3$ had higher rate of seedling emergence and faster growth of shoot than untreated seeds after sowing at 30˚C in growing medium in growth chamber.

• Horticultural Science & Technology
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• v.31 no.6
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• pp.700-705
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• 2013

This study was initiated to evaluate hydrophilic polymers (hydrogels) as a new solid matrix medium for seed-priming of Heteropappus arenarius Kitam. Solid matrix priming (SMP)-media were prepared with the combination of Na- and K-based hydrogels and hydrogels with three different dry levels (DC; 70%, 80%, and 90%). Priming was performed in the dark at 15 or $20^{\circ}C$ for 24 hours, and all primed seeds were incubated at $20^{\circ}C$ in the dark for the germination test. Non-primed seeds and seeds primed with distilled water (DW) were also included. To reach the germination rate of 50% ($T_{50}$), it took 4.0 days for non-primed seeds, and 3.6 and 3.9 days for DW-primed seeds at 15 and $20^{\circ}C$, respectively. Na-based hydrogel-primed seeds with 70% DC (Na 70%) showed the fastest germination, which respectively took and 1.9 and 1.8 days at 15 and $20^{\circ}C$ to $T_{50}$. K-based hydrogel-primed seeds with 70% DC showed the fastest germination among K-based hydrogels with various DC levels, but it took 0.6 days more to $T_{50}$ compared to Na 70%. The hydration rate (HR) of DW-primed seeds was 37% lower than that of Na 70%-primed seeds at $15^{\circ}C$ priming temperature, which indicates that Na 70% priming is the best solid matrix priming condition for promoting the germination of H. arenarius seeds.

• Journal of Magnetics
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• v.20 no.3
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• pp.290-294
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• 2015

To investigate the effects of alternating magnetic field intensity and stimulation time on the proliferation of human breast cancer cells (BT-20), we cultured the cells under a magnetic field with a saw tooth waveform of 2 kHz. The field intensities varied from 3 to 7 mT, and the stimulation time varied from 24 to 72 hours. Cell proliferation decreased dramatically to 40% during magnetic stimulation for 72 hours at 5 mT. However, the cells were not affected by a strong magnetic field of 7 mT. The p-values obtained using statistical package for social science software were below 0.05 for 5-7 mT. This means that the results have statistical significance. However, it is difficult to explain our results based on the physiology of cell membranes, which have various ionic flows at ion channels.