• Journal of the Korean Institute of Telematics and Electronics
• /
• v.27 no.2
• /
• pp.31-38
• /
• 1990

An antenna gain measurement system using an extrapolation technique is described. The technique is similar to the usual two-antenna method for absolute gain measurement system, but involves the measurement of the received signal as a function of seperation in short distances, and the signal-versus-seperation data is processed in a way that allows an extrapolation of the signal to "infinite" seperation. In this technique it is possible to obtain the near field gain as function of distance by combining the far field gain and a proximity correction factor. The results of gain measurements of standard gain horn antennas and OEG (open ended waveguide) antennas are also presented.

• Korean Journal of Animal Reproduction
• /
• v.22 no.4
• /
• pp.341-347
• /
• 1998

This study was conducted to determine changes in circulating progesterone and Insulin-like Growth Factor-1(IGF-1) concentrations according to daily gain of 0.5 and 0.7 kg ; from 33 weeks of age until the onset of regular oestrus cycles in the heifer of Hanwoo. In all animals, progesterone concentrations was undetectable until just before first oestrus. A small progesterone elevation of approximately 6 days duration(based upon the mean progesterone profile) preceded the first oestrus in 13 heifers. The mean age at first oestrus of the daily gain 0.7 kg(331.0$\pm$ 15.0 days) group was earlier than those of the daily gain 0.5 kg(358.9$\pm$7.9 days) group, and the mean weight at first oestrus of the daily gain 0.7 kg(236.0$\pm$4.7 kg) group was heavier than those of the daily gain 0.5 kg(224.8$\pm$9.7 kg) group. IGF-1 concentrations from day 3 to 15 of first oestrus were higher than those of the earlier luteal stage(Day 0~1) and the luteal regression stage (Day 18~20). IGF-1 concentrations according to the growth stage (from 33 weeks to 57 weeks) increased gradually. On the basis of these results, we suggest that the onset of first oestrus in Hanwoo heifer is about 345 day of age, and progesterone concentrations are closely related to the IGF-1 concentration.

• Parasites, Hosts and Diseases
• /
• v.46 no.2
• /
• pp.91-93
• /
• 2008

The weight gain phenomenon associated with sparganosis has been well documented and was first recognized in the 1960s. Many studies have been conducted regarding the plerocercoid growth factor in the larva of Spirometra mansoni. In the present study, we hypothesized that the weight gain may be affected by the adipocyte secreted hormones, i.e., adiponectin, which is secreted from the adipose tissues in case of tissue migrating parasitic infections. Specifically, we attempted to ascertain whether the serum levels of adiponectin change in murine sparganosis. However, serum adiponectin levels assayed by ELISA evidenced no significant changes after an experimental infection (P > 0.05). Finally, the weight gain phenomenon in mouse sparganosis is not associated with changes in adiponectin levels, and further investigations involving parasitic infection-induced weight gain remain necessary.

• Proceedings of the IEEK Conference
• /
• 2006.06a
• /
• pp.501-502
• /
• 2006

In this paper low power high gain amplifier is suitable for application in low power systems was designed and fabricated. The amplifier used both subthreshold bias for low power and positive feedback Q-enhancement technique for high gain. The amplifier used TSCM $0.18{\mu}m$ RF CMOS technology measures a power gain of 32.3dB, a quality factor of 366 and a power consumption of 3mW in a supply voltage of 1.8V.

• Journal of the Korean Institute of Telematics and Electronics D
• /
• v.35D no.6
• /
• pp.15-20
• /
• 1998

The linewidth enhancement factor $\alpha$ and fiber dispersion of 1.55 ${\mu}{\textrm}{m}$ strained multi-quantum well laser diodes are measured using small signal power modulation transfer function in a dispersive fiber. The measured fiber dispersion values are between 16.766 and 16.786ps/nm/km and these are the expected values from standard single mode fiber. To measure the $\alpha$ parameter in the actual operational range of the laser diodes, the dependence of $\alpha$ on laser output power is measured. The $\alpha$ parameter increases linearly as the power of the laser diode increases. This result can explain the non-linear gain effect on the $\alpha$ parameter more accurately than any other measurements.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.17 no.5
• /
• pp.423-430
• /
• 2012

An adaptive maximum power point tracking (MPPT) scheme employing a variable scaling factor is presented. A MPPT control loop was constructed analytically and the magnitude variation in the MPPT loop gain according to the operating point of the PV array was identified due to the nonlinear characteristics of the PV array output. To make the crossover frequency of the MPPT loop gain consistent, the variable scaling factor was determined using an approximate curve-fitted polynomial equation about linear expression of the error. Therefore, a desirable dynamic response and the stability of the MPPT scheme were maintained across the entire MPPT voltage range. The simulation and experimental results obtained from a 3 KW rated prototype demonstrated the effectiveness of the proposed MPPT scheme.

• Korean Journal of Veterinary Service
• /
• v.46 no.2
• /
• pp.107-113
• /
• 2023

Tenebrio molitor, rich in protein, is used as an alternative protein source. Many studies have evaluated Tenebrio molitor larvae (TML) for anti-obesity effects, fatty liver relief, antithrombosis, and antioxidant effects. In this study, we prepared an experimental diet by adding Tenebrio molitor larvae oil (TMLO) to feed and administered it to adult male ICR mice for six weeks. The study assessed the weight gain of mice, prothrombin time (PT), activated partial thromboplastin time (aPTT), blood coagulation time, and the activities of coagulation factor VII and coagulation factor XII. The weight gain of mice was suppressed in the groups fed with TMLO, indicating a potential anti-obesity effect. The blood coagulation time was delayed in the TMLO-fed groups, as evidenced by amplified PT and aPTT values. Furthermore, the activities of coagulation factor VII and coagulation factor XII were diminished in the TMLO-treated groups, indicating a potential thrombosis relieving effect. The concentrations of thromboxane B2 and serotonin declined in the TMLO-fed groups, signifying potential blood circulation effects. Finally, blood triglyceride and LDL-cholesterol concentrations were reduced in the TMLO-fed groups. In summary, TMLO supplementation may have an inhibitory effect on liver damage and blood clot formation caused by obesity.

• Journal of electromagnetic engineering and science
• /
• v.10 no.3
• /
• pp.86-91
• /
• 2010

In this paper, a double-layered frequency selective surface(FSS) superstrate was built and tested. The unit cell of the proposed FSS consists of a ring slot and a dipole-shaped structure and shows a complementary frequency response. Each unit cell is printed on two sides of a substrate. By using these double-layered structures, the first resonant frequency of the pass-band can be lowered. As a result, the size of the unit cell is minimized and the spacing between the other cells is reduced. The proposed FSS-dipole composite antenna is designed for the gain enhancement of wide-band code division multiple access(WCDMA) frequency bands(1.92~2.17 GHz) with a low quality factor(Q=0.17). To verify the gain enhancement performance of the FSS, an FSS-dipole composite antenna was created. Although the FSS layer enhances the gain of the primary radiation source of the dipole antenna, the FSS-dipole complex antenna cannot show a uniform gain over the entire desired frequency band. The experimental results show a gain enhancement of 3 dBi with an FSS superstrate in the WCDMA frequency band.

• Journal of the Korean Institute of Telematics and Electronics D
• /
• v.36D no.3
• /
• pp.75-84
• /
• 1999

Systematic studies for the effect of the linewidth enhancement factor, the confinement factor, the internal loss and the cavity length on the single mode gain difference and the frequency detuning are performed for $\lambda$/4 phase shifted DFB lasers above threshold. The above threshold characteristics are mainly determined by the linewidth enhancement factor, not by the confinement factor or the parameter defined by the product of the linewidth enhancement factor and the confinement factor. The normalized internal loss defined by the product of the internal loss and the cavity length mainly determines the above threshold characteristics compared to that of the internal loss or the cavity length alone. The effect of the cavity length on threshold characteristics is larger than that of the internal loss in the case of the same normalized internal loss. The above threshold characteristics of quantum well lasers are more resistant to the variations of the confinement factor and the normalized internal loss than those of bulk lasers due to the small linewidth enhancement factor.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.14 no.7
• /
• pp.762-768
• /
• 2003

This paper reports the effects of gain flatness for linearity improvement of feedforward power amplifier fur IMT-2000 band. To investigate the operational characteristics for gain flatness of each amplifier, WCDMA 4FA input signal was used and measured 10 W output power. Especially, linearity improvement for variation of gain flatness of each amplifier was investigated that have an effect on linearity improvement such as delay line, phase, and amplitude imbalances. Variation of gain flatness of main amplifier is 40 MHz and of error amplifier is 40 MHz and 80 MHz bandwidth, respectively. Measured results, gain flatness of main amplifier is less than 1.5 dB and of error amplifier is less than 0.5 dB for more than 20 dB improvement at 5 MHz offset. In addition to that results, the characteristics of feedforward amplifier are drastically varied by gain flatness of error amplifier and it is shown that gain flatness of error amplifier is more important factor for linearity improvement.