• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.6
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• pp.574-581
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• 2002

Microstrip $8{ imes}2$ sub-array antennas for a extension to active phased array antennas are designed, fabricated and measured for TX/RX dual operation in satellite communication and a reception of satellite broadcasting. For the frequency range from 11.7 to 12.75 GHz for RX and from 14 to 14.5 GHz for TX, two orthogonal linear polarizations of ${pm}45^{\circ}$ are used to transmit and receive simultaneously with one radiator. They adopt dual resonance between two patches for wideband characteristics in RX band and show isolation characteristics over 20 dB. An electrical beam tilt of $30^{\circ}$ is achieved and a tapered power distribution, narrow element spacing are used for the purpose of low side-lobe characteristics.

• Journal of the Optical Society of Korea
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• v.17 no.1
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• pp.44-49
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• 2013

A transimpedance amplifier (TIA)-optical receiver (Rx) using two intersecting active feedback system with regulated-cascode (RGC) input stage has been designed and implemented for optical interconnects. The optical TIA-Rx chip is designed in a 0.13 ${\mu}m$ CMOS technology and works up to 10 Gbps data rate. The TIA-Rx chip core occupies an area of 0.051 $mm^2$ with power consumption of 16.9 mW at 1.3 V. The measured input-referred noise of optical TIA-Rx is 20 pA/${\surd}$Hz with a 3-dB bandwidth of 6.9 GHz. The proposed TIA-Rx achieved a high gain-bandwidth product per DC power figure of merit of 408 $GHz{\Omega}/mW$.

• ETRI Journal
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• v.42 no.6
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• pp.943-950
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• 2020

We propose 8.2-GHz band radar RFICs for an 8 × 8 phased-array frequency-modulated continuous-wave receiver developed using 65-nm CMOS technology. This receiver panel is constructed using a multichip solution comprising fabricated 2 × 2 low-noise amplifier phase-shifter (LNA-PS) chips and a 4ch RX front-end chip. The LNA-PS chip has a novel phase-shifter circuit for low-voltage operation, novel active single-to-differential/differential-to-single circuits, and a current-mode combiner to utilize a small area. The LNA-PS chip shows a power gain range of 5 dB to 20 dB per channel with gain control and a single-channel NF of 6.4 dB at maximum gain. The measured result of the chip shows 6-bit phase states with a 0.35° RMS phase error. The input P1 dB of the chip is approximately -27.5 dBm at high gain and is enough to cover the highest input power from the TX-to-RX leakage in the radar system. The gain range of the 4ch RX front-end chip is 9 dB to 30 dB per channel. The LNA-PS chip consumes 82 mA, and the 4ch RX front-end chip consumes 97 mA from a 1.2 V supply voltage. The chip sizes of the 2 × 2 LNA-PS and the 4ch RX front end are 2.39 mm × 1.3 mm and 2.42 mm × 1.62 mm, respectively.

• Proceedings of the KSMRM Conference
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• 2001.11a
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• pp.143-143
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• 2001

목적： 현재 3.0T MRI system은 세계적으로 개발이 진행되고 있는 가운데, 3.0T에서 사용할 수 있는 RF coil의 개발이 시급한 상황이다. 1.0T 및 1.5T MRI 와는 달리 3.0T에서 사용할 수 있는 Body coil 및 그에 따른 High power RF amplifier 제작에 많은 제약이 있다. 작은 용량의 RF amplifier를 이용하여 신체의 부분을 촬영 하고자 한다면, Tx/Rx 가능한 coil을 이용하면 가능할 것이다. 이러한 이유로 본 연구에서는 Tx/Rx 가능한 Quadrature type C-spine RF coil을 설계, 제작하여 3.0T 고자장 자기공명 영상장치에서의 임상진단 활용범위를 확대하였다.

• Communications of the Korean Mathematical Society
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• v.11 no.1
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• pp.215-224
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• 1996

In this paper, we classify hypersurfaces M in $S^{n+1}_{1}$ or in $H^{n+1}$ satisfying $\Delta x = Rx + b$.

• Bulletin of the Korean Mathematical Society
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• v.53 no.3
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• pp.779-791
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• 2016

Transfer of homological properties under base change is a classical field of study. Let $R{\rightarrow}S$ be a ring homomorphism. The relations of Gorenstein projective (or Gorenstein injective) dimensions of unbounded complexes between $U{\otimes}^L_RX$(or $RHom_R(X,U)$) and X are considered, where X is an R-complex and U is an S-complex. In addition, some sufficient conditions are given under which the equalities $G-dim_S(U{\otimes}^L_RX)=G-dim_RX+pd_SU$ and $Gid_S(RHom_R(X,U))=G-dim_RX+id_SU$ hold.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.2
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• pp.59.2-59.2
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• 2017

The Submillimeter Array (SMA) has provided forefront capabilities for high spatial and spectral resolution observations at submillimeter wavelengths from its excellent site on Mauna Kea, Hawaii since 2004. The SMA has continuously enhanced its capability. It is now equipped with two receivers in the 1.3 mm band (Rx230/Rx240) and two in the 0.85 mm band (Rx345/Rx400). The total bandwidth available is 8+8 GHz (per receiver) in the dual band or polarization mode. To maintain a leading role in the ALMA era, the SMA project is now upgrading its receivers, IF signal transport and correlator system. The new wideband SMA - the wSMA - will provide the instantaneous coverage of 56 GHz. In this presentation, I will introduce the latest status of the SMA, upgrade plan to the w-SMA, the possible science cases with the w-SMA, and the roles of the w-SMA in the ALMA era.

• Proceedings of the KSMRM Conference
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• 2001.11a
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• pp.175-175
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• 2001

목적： 현재 3.0T MRI system은 세계적으로 개발이 진행되고 있는 가운데, 3.0T에서 사용할 수 있는 RF coil의 개발이 시급한 상황이다. 1.0T 및 1.5T MRI 와는 달리 3.0T에서 사용할수 있는 Body coil 및 그에 따른 High power RF amplifier 제작에 많은 제약이 있다. 작은 용량의 RF amplifier를 이용하여 신체의 부분을 촬영 하고자 한다면, Tx/Rx 가능한 coil을 이용하면 가능할 것이다. 이러한 이유로 본 연구에서는 Tx/Rx 가능한 Quadrature type T/L-spine RF coil을 설계, 제작하여 3.0T 고자장 자기공명 영상장치에서의 임상진단 활용범위를 확대하였다. 3.0 Tesla 자기공명 영상장치에 사용을 위한 Quadrature type의 L-spine TX/RX RF 코일을 개발하여 고자장 자기공명 영상장치에서의 임상진단 활용범위의 확대를 목적으로 한다.

• Proceedings of the KSMRM Conference
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• 2001.11a
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• pp.145-145
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• 2001

목적 현재 3.0T MRI system은 세계적으로 개발이 진행되고 있는 가운데, 3.0T에서 사용 할 수 있는 RF coil의 개발이 시급한 상황이다. 1.0T 및 1.5T MRI 와는 달리 3.0T에서 사용할 수 있는 Body coil 및 그에 따른 High power RF amplifier 제작에 많은 제약이 있다. 작은 용량의 RF amplifier를 이용하여 신체의 부분을 촬영 하고자 한다면, Tx/Rx 가능한 coil을 이용하면 가능할 것이다. 이러한 이유로 본 연구에서는 Tx/Rx 가능한 Quadrature type Th-spine RF coil을 설계, 제작하여 3.0T 고자장 자기공명 영상장치에서의 임상진단 활용범위를 확대하였다. 3.0 Tesla 자기공명 영상장치에 사용을 위한 Quadrature type의 L-spine TX/RX RF 코일을 개발하여 고자장 자기공명 영상장치에서의 임상진단 활용범위의 확대를 목적으로 한다.

• YAKHAK HOEJI
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• v.55 no.5
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• pp.432-439
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• 2011

The effects of characteristics of community pharmacists on consultation time for prescription (RX) and nonprescription drugs (nRX) were investigated. A crosssectional descriptive design was established with a self-administered anonymous mail survey. Response rate was 52%. Significant pharmacists' factors related to having less than 3 minutes consultation for RX were one's dispensing duties exceeding 50%, low satisfaction with one's own level of consultation, working at the pharmacies nearby clinics, or shorter duration of consultation time for nRX. Consultation promoting conditions should be built up for the provision of sufficient consultation.