• Journal of Digital Convergence
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• v.11 no.7
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• pp.201-207
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• 2013

The chirp signaling has been mainly used in radar systems due to its good correlation characteristics, and nowadays it is applied to real time locating system(RTLS). The RTLS with chirp signaling was chosen as a standard such as ISO/IEC 24730-5 and IEEE 802.15.4a. In this paper, the performance of a real time locating system with chirp signaling was evaluated and simulated with relative distance error rates. We considered three cases of S/I = -30[dB], -20[dB], and -10[dB] with Rician factor K=10 and K=20. The performance was enhanced with K factor improvement by 25%, 27% and 50% for respective three cases of S/I. As results, in case of S/I < -20[dB], the minimum signal power is required for performance improvement even though the line of sight component is helpful. And also, in case of S/I ${\geq}$ -20[dB], as the line of sight component is stronger the better performance is obtained.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.3
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• pp.358-365
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• 2008

A differential-gain-controlled LNA is designed and implemented in 0.18 um CMOS technology for $3.1{\sim}4.8GHz$ UWB system. In high gain mode, measurements show a differential power gain of $14.1{\sim}15.8dB,\;13.3{\sim}15dB$, respectably, an input return loss higher then 10dB, an input IP3 of -19.3 dBm, a noise figure of $4.85{\sim}5.09dB$, while consuming only 19.8 mW of power from a 1.8V DC supply. In low gain mode, measurements show a differential power gain of $-6.1{\sim}-4.2dB,\;-7.6{\sim}-5.6dB$, respectably, an input return loss higher then 10dB, an input IP3 of -1.45 dBm, a noise figure of $8.8{\sim}10.3dB$, while consuming only 5.4mW of power from a 1.8V DC supply.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.1 s.116
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• pp.37-43
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• 2007

In this.paper, we introduce design and implementation results of the single balanced diode mixer for European point-to-point microwave radio in order to improve flatness performance. When a resonator such as RF filter is integrated with a mixer, impedance characteristic of 50 ohm is maintained only in RF band, not in LO band resulting deterioration of flatness performance because of LO power variation on the diode. In the paper, we suggest a design method of mixer integrated with image rejection filter and LO harmonic filter to have a better performance of flatness using embedding electrical length between filter and mixer's port. Frequency specification of fabricated mixer is $21.2{\sim}22.6\;GHz$ for RF, $19.32{\sim}20.72\;GHz$ for LO and 1.88 GHz+/-50 MHz for IF, respectively. Measured results show conversion loss of 8.5 dB, flatness of 2 dB, input PldB of 8 dBm, IIP3 of 15 dBm under LO power level of 10 dBm. Return losses of RF, LO and IF port are under -12 dB, -10 dB and -5 dB, respectively. Isolations of LO/RF and LO/IF are 20 dB and 50 dB, respectively.

• Journal of Korean Ophthalmic Optics Society
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• v.14 no.2
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• pp.1-8
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• 2009

Purpose: The purpose of this study is to compare degrees of asthenopia in after wearing of dispensed reading glasses with different criterion of P.D. Methods: The person who has minus near correction power (distance correction value (-)) is compared to the degree of asthenopia by wearing of dispensed reading glasses with near P.D(-B) and distance P.D. The person who has plus near correction power is compared to degree of asthenopia by wearing of dispensed reading glasses with near P.D-B, distance P.D, near P.D-A. The "Near-P.D-A" means reduced optical centre distance of reading glasses of positive correction value at which the same effect of prism B.O through near visual point in distance glasses exist at near visual point in reading glasses. Results: When near correction value is (-), dispensed reading glasses with distance P.D have caused less asthenopia than dispensed glasses with near P.D-B. When the near correction value is (+), we cannot confirm that which P.D is more useful for reading glasses. As a result of this study, dispensed reading glasses with near P.D-A have caused less asthenopia than another criterion of P.D. Conclusion: The effect of prism B.I through a near visual point in distance glasses ((-) correction value) reduce convergence demand. Therefore (-) correction value-reading glasses support convergence in near vision, because the effect of prism B.I of reading glasses is smaller than that of distance glasses. When the near correction value is (+), centration points can be determined by one of near P.D-A, near P.D-B, distance P.D.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.2 no.4
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• pp.635-641
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• 1998

This paper presents development of a small size LNA operating at 824 ∼ 849 MHz used for a receiver of a CELLULAR CDMA Base station and a transponder. Using resistive decoupling circuits, a signal at low frequency is dissipated by a resistor. This design method increases the stability of the LNA and is suitable for input stage matching. The LNA consists of low noise GaAs FET ATF-10136 and internally matched VNA-25. The LNA is fabricated with both the RF circuit and the self-bias circuits in aluminum housing. As a result, the characteristics of the LNA implemented here shows above 35dB in gain and below 0.9dB in noise figure, 18.6dBm P1dB power, a typical two tone IM3, -31.17dB with single carrier backed off 10dB from P1dB.

• Journal of the Korean Society of Radiology
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• v.12 no.3
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• pp.335-341
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• 2018

With the improvement of medical state, patients' expectations for the most advanced medical equipment are increasing. Particularly, Magnetic Resonance Image (MRI) is used as one of the core image diagnosis methods in all clinical area. However, it has been reported that many of patients who go through the examination suffer from anxiety to the severe noise level during the examination. In this study, both the noise reduction evaluation of headsets with sound-blocking materials added to existing sound-absorbing materials and the existence of sound blocking materials as artifacts on the examination image are tested. An MRI test noise is recorded as a speaker by cross-ordination the sound material (sponge) and the sound material (acrylic plate, copper plate, and 3D copper plate) inside the headset made from 3D pring. A quantitative assessment of headsets showed that the average headset value was 81.8 dB. The average dB value of the most soundproof material combination(Copper, acrylic plate, sponge, sponge) headsets on headsets with added charactering material was measured at 70.4 dB, and MRI showed that the copper was diamagnetic substance and excluded. The second most soundproof headset(Sponge, acrylic plate, 3D copper plate, sponge) was measured at 70.6 dB and MRI showed no artifacts. The same simulation of the material printed with a 3D copper PLA containing approximately 40 % copper powder resulted in no artifacts, therefore, the material output as a 3D printing was better suited for use. For MRI related research, the mutual development of 3D printing is highly anticipated.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.2
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• pp.293-298
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• 2001

EB-NMP free standing film is manufactured from NMP solution of polyaniline(emeraldine base EB). Also ES(emeraldine salt EB . HCl) film is manufactured by doping of EB-NMP film with 1 mole HCI aqueous solution. And EB-mixture films containing conductor(carbon black, graphite, Ag etc.) are prepared, In this study, electromagnetic interference shielding efficiency(EMI SE) of ES free standing film ($\sigma$=5 S/cm, t=0.14mm) is 23~25 dB in the frequency range of 10 MHz~1 GHz. ES-mixture(carbon black, graphite, Ag etc.) films, polyaniline film doped camphorsulfonic acid(CSA) show higher EMI SE(30~34 dB, 36~42 dB, 44~52 dB, 34~43 dB) property than that of ES free standing film, respectively.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.35 no.1
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• pp.19-24
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• 1999

This paper is second part on the auditory thresholds and fish behaviors to the underwater sounds for luring of target species at the set-net in the coast of Cheju. In order to obtain the critical ratio of yellow tails(Seriola quinqueradiata) and the emission level of underwater sound for luring of them, we make experiments to measure the auditory threshold of them using conditioning with electric shock. In state that the white noise with 10dB higher sound pressure level than ambient noise is emitted, the auditory thresholds of yellow tails are measured with 100~116.5dB and they are higher than those in state of no emission of white noise by the masking effects of it. Although sound pressure level of background noise go down, the auditory thresholds go up with frequency above than 300Hz.The critical ratio of yellow-tails in frequency of 80Hz, 100Hz, 200Hz, 500Hz, 800Hz are 46dB, 40dB, 50dB, 52dB, 60dB, 70dB respectively. The sound pressure level of which the signal sound is recognized by yellow tails under the ambient noise is above 100dB and the critical ratio of them is above 40dB.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2000.10a
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• pp.186-189
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• 2000

In this paper, we have designed a bandpass filter to apply the downconverter of the K-band Mu-hung-hwa satellite. To pass only the 25-30% of the bandwidth at the center frequency of 19.6GHz, we have designed a six-order interdigital bandpass filter using microstrip lines. Simulation result of optimization show that insertion loss is -0.275dB and reflection coefficient is -20.95dB at the passband frequency. measurement is determined center frequency, 19.150Hz, insertion loss, -4.1dB, input reflection coefficient. -l5dB and output reflection coefficient -l6dB.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2003.05a
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• pp.51-59
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• 2003

Marine Casualty Forecasting System (MCFS) is to broadcast the prediction number and risk level of marine casualties as like daily weather forecasting. The MCFS consists of marine casualty numerical D/B, prediction model and, three-dimensional statistics visualization system. The implementation procedure for the numerical D/B is described in the paper. The data relating to a total of 724 ship casualties in the west-southern sea area (latitude 33$^{\circ}$N∼35$^{\circ}$ and longitude 124$^{\circ}$E∼127$^{\circ}$E) of Korean peninsula for 11 years (1999∼2000) have been compiled. The analysis method of numerical D/B is proposed and discussed its usability.