• Journal of electromagnetic engineering and science
• /
• v.5 no.4
• /
• pp.153-160
• /
• 2005

In this paper, the novel microwave oscillator incorporating a planar cavity resonator(PCR) is presented to reduce the phase noise of the oscillator in a planar environment. Compared to the conventional planar( $\lambda$/4 open stub resonator), the phase noise is improved about 16 dBc/Hz @100 kHz. The design of the oscillator is based on a reflection type configuration using the low 1/f SiGe HBT transistor(LPT16ED). The output power is measured 2.76 dBm at 12.5 GHz. In this paper, the oscillator used to the PCR can be expected to provide a solution for low phase noise oscillator in microwave circuits.

• 한국정보통신설비학회:학술대회논문집
• /
• 2002.08a
• /
• pp.31-34
• /
• 2002

본 논문은 Ku-band(12.4-18 GHz) 위성통신 시스템 및 이동통신 중계기용 송수신부에 사용되는 고안정도 전압제어 유전체 공진기(Voltage Controlled Dieletric Resonator Oscillator)의 설계 및 제작에 대해 논하였다. 유전체 공진기(Dielectric Resonator)의 등가회로 모델을 이용하여 유전체 공진 발진기(Dielectric Resonator Oscillator)를 설계 알고리즘화 하였다. 유전체 공진 발진기와 바렉터 다이오드를 이용하여 13.4 GHz의 전압 제어 유전체 공진 발진기를 제작하였다. 이때의 출력 전력은 +12dBm이고 위상잡음은 offset 주파수 100kHz에서 -105 dBc/Hz로 측정되었다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2000.05a
• /
• pp.433-437
• /
• 2000

본 논문에서는 데이터 전송용 특정 소출력 무선국용 무선기기의 송수신단의 회로를 설계하고 제작하여 특성을 측정하였다. 주파수 대역은 424.7~424.95MHz이고, 반이중(Half Duplex Communication) 통신방식, PLL Synthesized, 20 Channel, 12.5kHz Channel Bandwidth 그리고 FSK Modulation/Demodulation 방식을 사용하였다. 송신단은 저잡음 증폭기와 전력증폭기를 사용하여 10mW의 출력으로 설계하였고, 발생되는 스퓨리어스를 감쇄시키기 위해 저역통과필터와 공진 회로로 구성하였다. 수신단은 Dual Conversion 방식을 사용하였다. 설계한 결과, 송신단의 출력은 9.71dBm, 스퓨리어스특성 47dBc 그리고 수신단은 감도가 -113dBm에서 Jitter가 $\pm$12.3%로 나타났다.

• Journal of the Korean Institute of Telematics and Electronics A
• /
• v.33A no.6
• /
• pp.72-80
• /
• 1996

This paper presetns the development of a SSPA operating at KU-band(14~14.5 GHz) in order of replace TWTA used in the terrestria transponder of a satellite communication. The driving stage of SSPA uses internally matched 2W, 4W, 8W FET and the power stage is coupled with two internally matched 8W FET by branch-line cominer. The SSPA is fabricated with oth the RF circuit and the bias circuitry operating temperature compensation, regulation and sequence on aluminum housing. The SSPA testing resutls implemented in this way show 24.8$\pm$1dB small-signal gain, 41dBm P1dB power, a typical two tone C/IM3, -33dBc with single carrier backed off 6dB from p1dB, and gain stability over temeprature (-30~50)$\pm$1dB.

• KIEE International Transactions on Electrophysics and Applications
• /
• v.4C no.6
• /
• pp.272-275
• /
• 2004

A balanced single side-band (SSB) mixer employing a sub-harmonic configuration is designed for up and down conversions in K-band. The designed mixer uses anti-parallel diode (APD) pairs to effectively eliminate even harmonics of the local oscillator (LO) spurious signal. To reduce the odd harmonics of LO at the RF port, we employ a balanced configuration for LO. The fabricated chip shows 12$\pm$2dB of conversion loss and image-rejection ratio of about 20dB for down conversion at RF frequencies of 24-27.5GHz. As an up-conversion mode, the designed chip shows 12dB of conversion loss and image-rejection ratio of 20 ～ 25 dB at RF frequencies of 25 to 27GHz. The odd harmonics of the LO are measured below -37dBc.

• Animal Systematics, Evolution and Diversity
• /
• v.29 no.2
• /
• pp.144-151
• /
• 2013

Two marine hypotrichous ciliates, Anteholosticha petzi and Ponturostyla enigmatica, were collected from the Yellow Sea and the Korea Strait, respectively, and described using live observation and protargol-impregnated specimens. Furthermore, the nuclear small subunit ribosomal RNA gene of each was sequenced and compared to previously annotated sequences retrieved from the GenBank. Anteholosticha petzi is characterized by 3 frontal cirri (FC), 2 frontoterminal cirri (FTC), 8-12 transverse cirri (TC), 1 buccal cirrus (BC), 9-12 midventral pairs (MP), 3 bipolar dorsal kineties (DK), and 3 types of colorless cortical granules. Ponturostyla enigmatica is characterized by 8 FC, 5 ventral cirri (VC), 5-7 TC, 6-7 marginal rows (MR) on each side, 4 complete and 2-3 partial DK, and greenish cortical granules. This is the first identification and description of these 2 species, A. petzi and P. enigmatica, in South Korea.

• Smart Media Journal
• /
• v.12 no.5
• /
• pp.9-16
• /
• 2023

In the recommendation system of the credit card company, it is necessary to understand the customer patterns to predict a customer's next merchant based on their histories. The data we want to model is much more complex and there are various patterns that customers choose. In such a situation, it is necessary to use an effective model that not only shows the relevance of the merchants, but also the relevance of the customers relative to these merchants. The proposed model aims to predict the next merchant for the customer. To improve prediction performance, we propose a novel model, called Customer-based Recommendation Model (CRM), to produce a more efficient representation of customers. For the next merchant recommendation system, we use a synthetic credit card usage dataset, BC'17. To demonstrate the applicability of the proposed model, we also apply it to the next item recommendation with another real-world transaction dataset, IJCAI'16.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.5 no.7
• /
• pp.1326-1331
• /
• 2001

This paper has been studied about design of a transceiver for data transmission. The transceiver has bandwidth of 424.7~424.95 MHz and uses half duplex communication method, PLL synthesized, 20 channel, 12.5 KHz channel bandwidth and FSK modulation/demodulation method. The transmission set is designed using low noise amplifier and power amplifier Also, it consists of low pass filter and resonation circuit for decrease of spurious signal. The receiver set is designed using dual conversion method. Finally, the transceiver set achieves the following characteristics 9.71dbm output power, 47dbc spurious property and $\pm$12.3 Jitter at sensitivity of -1134dbm.

• Journal of Life Science
• /
• v.17 no.12
• /
• pp.1744-1753
• /
• 2007

The purpose of this study was to provide obese middle school girls with walking and behavior modification program(WBMP) by investigating effects of the exercise on their body composition(BC), physical fitness(PF) and metabolic syndrome(MS). Analysis result of the difference between before and after the exercise(paired and independent t-test) was acquired by measuring BC, PF and MS for 12 weeks(60min/day, three a week). 24 Volunteers were 14 years over ${\geq}223.64kg/m^2$ and 15 years over ${\geq}24.00kg/m^2$. In the body composition, waist circumference(WC), body fat mass(BFM), %fat, arm muscle circumference(AMC), total body water(TBW), physical score(PS) were significant difference between the exercise group(EG) and the control group(CG), also including all factors in PF. The components of metabolic syndrome were significant difference between EG and CG, but HDL-C, systolic & diastolic blood pressure were no difference. The metabolic syndrome factors by separate of waist girth were no difference between EG and CG, but BMI, diastolic blood pressure were significant difference. The prevalence of metabolic syndrome was 4 of 24(16.7%) before intervention, but it dropped from 2 to 1 after intervention in WBMP. The components of metabolic syndrome was distributed a big WC>low HDL-C>high TG>hypertension. The changes of AMC, We, PS, BW, 50m run and BFM effect the factors on BMI(35%), WHR(waist-hip ratio, 69%), HDL-C(42%), fasting blood glucose(65%), HOMA-IR index(34%) and systolic blood pressure(39%) respectively. There were significantly increased in breakfast frequency, walking steps, and meal eating period, but decreased in snacks and eating out in exercise group.

• Proceedings of the IEEK Conference
• /
• 2006.06a
• /
• pp.495-498
• /
• 2006

This paper reports a high power 60 GHz push-push oscillator fabricated using 0.12 um metamorphic high electron-mobility transistors (mHEMTs). The devices with a $0.1{\mu}m$ gate-length exhibited good DC and RF characteristics such as a maximum drain current of 700 mA/mm, a peak gm of 660 mS/mm, and an $f_T$ of 170 GHz. By combining two sub-oscillators having $6{\times}50{\mu}m$ periphery mHEMT, the push-push oscillator achieved a 6.3 dBm of output power at 59.5 GHz with more than -35 dBc fundamental suppression. This is one of the highest output power obtained using mHEMT technology without buffer amplifier, and demonstrates the potential of mHEMT technology for cost effective millimeter-wave commercial applications.