• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.5
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• pp.513-520
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• 2003

In this paper, a novel design concept of frequency doubler using feedforward technique and DGS microstrip line is proposed. The feedforward loop plays a role of fundamental frequency suppression and DGS microstrip line suppresses over the 3rd order harmonic components. By using this new concept, the high suppression for the undesired signals could be achieved easily. The proposed technique is experimentally demonstrated in 1.87 GHz-to-3.74 GHz frequency doubler. The output power of -3 dBm at the frequency of 3.74 GHz(2f$\_$0/) is measured with 42.9 dB suppression of the fundamental frequency signal(f$\_$0/), 20.2 dB suppression of the 3rd harmonic signal(3f$\_$0/) and B9.7 dB suppression of the 4th harmonic signal(4f$\_$0/). The conversion loss of -2.34 dB ∼ -5.8 dB at the bandwidth of 100 MHz, the phase noise of -97.51 dB/Hz(＠10 kHz) were measured.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.6 no.1
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• pp.28-36
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• 1995

In this paper, a design method of multiple n-way low loss power divider for x-band is propossed. To decrease loss, only two-stages of transmission lines are used with isolation resistors for match. Ex- perimental results for 3-way and 4-way power dividers have the divided power of 5.54~6.17dB and 6.76~7.37 dB, the return loss of more than 17dB and 12dB, and the isolation of more than 18dB and 10dB at center frequency, respectively, The measured results show good agreement with the theoretical analysis.

• Proceeding of Spring/Autumn Annual Conference of KHA
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• 1994.05a
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• pp.11-17
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• 1994

The increase of road traffic niose in residential area has been considered to be a serious environmental problem to deteriorate a living condition. The understanding of noise environment in multiple family housing is needed for noise reduction. This study attempts to find out the characteristics of noise environment. For this purpose, the field survey has been carried out to investigate the noise environment(sound level, quality of sound) and the residents' responses(noiseness, annoyance) for noise environment based on 173 households living in 3 apartment compounds built in Pusan according to site location. The major findings are as follows : 1. The sound levels by road traffic noise were measured by dB(A) and dB(Lin). The sound levels were : 77.0dB(A), 86.6dB(Lin) in D-Apt, 73.3dB(A), 82.6dB(Lin) in K-Apt, and 59.1dB(A), 74.6dB(Lin) in M-Apt. Especially, the difference between dB(A) and dB(Lin) was very big in the cae of M-Apt with a barriers for traffic noise reduction. 2. The internal sound levels were shown the soudn attenuation by horizontal distance and by opening or shuting condition of windows.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.2 s.93
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• pp.139-143
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• 2005

In this paper, we propose the design on LNA and Down-mixer for MB-OFDM UWB using $0.18\;{\mu}m$ CMOS. LNA, Down-mixer design result shows that it covers the frequency range ken 3 GHz to 5 GHz. The LNA gain is larger than 12.8 dB, and noise figure about 2.6 dB. Double balanced differential down-mixer is designed less than 2 dB gainflatness, and it has over 30 dB LO leakage, feedthrough characteristics.

• Journal of the Korean Society of Food Science and Nutrition
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• v.44 no.4
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• pp.524-531
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• 2015

Antioxidant activities and in vitro anticancer effects of bamboo salt doenjang on HT-29 human colon cancer cells were studied. 3Y3B-D (three-year fermentation using three-time baked bamboo salt doenjang), 3Y9B-D (three-year fermentation using nine-time baked bamboo salt doenjang), 6Y3B-D (six-year fermentation using three-time baked bamboo salt doenjang), and 6Y9B-D (six-year fermentation using nine-time baked bamboo salt doenjang) were compared to C-D (commercial doenjang) and 3B-S (cooked soy beans prepared using three-time baked bamboo salt). There were no differences between experimental groups in pH, amino-type nitrogen, or ammonia-type nitrogen levels. 6Y9B-D showed the highest antioxidative effect, followed by 6Y3B-D, 3Y9B-D, and 3Y3B-D, in order. 6Y9B-D showed the highest total polyphenol concentration. 6Y9B-D showed the highest anticancer effect, as determined by MTT assay, as well as levels of the pro-inflammatory cytokines including TNF-${\alpha}$, IL-6, iNOS, and COX-2, followed by 6Y3B-D, 3Y9B-D, and 3Y3B-D, in order. From the results above, 6Y9B-D showed the highest antioxidative and anticancer effects, followed by 6Y3B-D, 3Y9B-D, 3Y3B-D, C-D, and 3B-S.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.19 no.1
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• pp.25-32
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• 1983

The corner reflector is used to increase the echoing area of radar targets in the air, and it can also be applied to increase the echoing area of the sonar targets under water. As the basic research for this application, the authors investigated the ultrasonic reflection characteristics under water for the corner reflector which was made of aluminum plate. The experiments were made by pulse measuring method with the magnetostrictive ferrite transducers of 28, 50 and 75KHz in the experimental water tank. The results obtained are as follows; 1. The target strength of corner reflectors were increased in proportion to the diameter and were greater at higher frequency of 75KHz than at lower frequency of 28KHz. 2. In the case of 5 corner reflectors of 150mm in diameter which have corner angles of 15$^{\circ}$, 30$^{\circ}$, 45$^{\circ}$, 60$^{\circ}$ and 90$^{\circ}$the measured values of the maximum target strength at 75KHz were-25.0 dB, -17.2dB, -15.1dB, -13.4dB and 11.0dB, and then the number of main lobes showing the maximum target strength in the backscattering patterns were 24, 12, 8, 6 and 4, respectively. 3. When 7 corner reflector of 80mm in diameter and 90$^{\circ}$ in the corner angle was located on the minor axis of the horizontal section with directional angles of 0$^{\circ}$, 2.5$^{\circ}$, 5.0$^{\circ}$, 7.5$^{\circ}$, 10$^{\circ}$ and 12.5$^{\circ}$ against the sound beam axis, the measured values of the target strength on each position at 75KHz were -21.2dB, -21.9dB, -26.0dB, -30.5dB and -36.8dB, respectively.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.5
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• pp.109-114
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• 2023

In this paper, a 2-channel Image-Reject receiver using a 65-nm CMOS process is presented for Ka-band compact radars. The designed receiver consists of Low-Noise Amplifier (LNA), IQ mixer, and Analog Baseband (ABB). ABB includes a complex filter in order to suppress unwanted images, and the variable gain amplifiers (VGAs) in RF block and ABB have gain tuning range from 4.5-56 dB for wide dynamic range. The gain of the receiver is controlled by on-chip SPI controllers. The receiver has noise figure of <15 dB, OP1dB of >4 dBm, image rejection ratio of >30 dB, and channel isolation of >45 dB at the voltage gain of 36 dB, in the Ka-band target frequency. The receiver consumes 420 mA at 1.2 V supply with die area of 4000×1600 ㎛.

• Korean Journal of Microbiology
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• v.36 no.4
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• pp.267-272
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• 2000

A 1.7-kb fragment containing the nodD1 genes of Bradyrhizobium sp. (Cassia) CN9135 was amplified by PCR with primers based on B. japonicum USDA110. This fragment was cloned and sequenced. Analysis of the sequence showed open reading frames highly homologous to nodD1 from other bradyrhizobial sources. The sequence showed higher homology to nodD1 gene of B. elkanii than to those from b. japonicum. Our results suggest that Bradyrhizobium sp. (Cassia) CN9135 may be more closely related to B. elkanii than to B. japonicum.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.8
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• pp.16-21
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• 2007

CMOS variable gain amplifier (VGA) IC designs for the structure monitoring systems of the telemetries were developed. A three stage cascaded VGA using a differential amplifier and a linear-in-dB controller is presented. A proposed VGA is a modified version of a conventional VGA such that the gain is controlled in a linear-in-dB fashion through the current ratio. The proposed VGA circuit introduced in this paper has a dynamic range of 77 dB with 1.5 dB gain steps. It also achieved a gain error of less than 1.5 dB over 77 dB gain range. The VGA can operate up to 10MHz dissipating 13.8 mW from a single 1.8 V supply. The core area of the VGA fabricated in a Magnachip $0.18{\mu}m$ standard CMOS process was about $430{\mu}m{\times}350{\mu}m$. According to measurement results, we can verify that the proposed method is reasonable with regard to the enhancement of dynamic range and the better linear-in-dB characteristics.

• The Journal of the Acoustical Society of Korea
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• v.40 no.1
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• pp.46-54
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• 2021

In this paper, active noise control was performed to reduce radiated noise in the low frequency band of dishwashers. First, through an analysis of the noise environment of the dishwasher, it was confirmed that the pump noise contributed the most to the radiated noise in the low frequency band, From the result of the noise environment analysis, the reference signal was selected to be the vibration signal of the pump body. The reference signal was obtained by using the accelerometer on the pump body, which can prevent acoustic feedback. The error signal sensor was selected as a microphone located at 1 m in front of the dishwasher and 0.5 m in height. And to design the controller, the error signal and the reference signal were measured at the operational rpms of the dishwasher at 2,500 rpm, 2,600 rpm and 2,800 rpm, and the secondary path transfer function was measured. The designed controller was mounted on Digital Signal Processor (DSP) equipment, and the control performance was verified experimentally. As a result of the measurement at the 3 operational rpms, the 7th multiple component of pump operating frequency decreased by 1.93 dB, 4.43 dB, 5.15 dB per rpm, and the 12th multiple component decreased by 6.67 dB, 2.34 dB, 4.28 dB per rpm. And overall Sound Pressure Level (SPL) decreased by 0.84 dB, 2.58 dB, 1.48 dB by rpm.