• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.3 s.106
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• pp.239-248
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• 2006

In this paper, the cryogenically cooled low noise amplifier module for radio telescope receiver front-end using pHE-MT MMIC is designed and fabricated. In the selection of MMIC, the MMIC fabricated with the pHEMTS providing successful cryogenic operation are chosen. They are mounted in the housing using the thin film substrate. In the design of the housing, the absorber and the elimination of the gap between the carrier and the housing as well removed the unnecessary oscillations by its structure. The mismatch is improved by ribbon-tuning to provide the best performance at room temperature. The fabricated module shows the gain of $35dB{\pm}1dB$ and the noise figure of $2.37{\sim}2.57dB$ at room temperature over $21.5{\sim}23.5GHz$. In the cryogenic temperature of $15^{\circ}K$ cooled by He gas, the measured gain was above 35 dB and flatness ${\pm}2dB$ and the noise temperatures of $28{\sim}37^{\circ}K$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.1217-1219
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• 2003

상용화되어 있는 이동통신 기기의 Front-end 부분은 듀플렉서와 필터를 포함하는 수동소자로 구성되어 있다. 듀플렉서의 임피던스 정합선로는 전송선로 이론으로부터 설계하며, 단순하게 ${\lambda}=1/4$ 파장 길이의 정합 선로를 설치하는 것이기 때문에 정합선로를 이용한 듀플렉서 성능을 극대화하기 위한 설계의 융통성이 없는게 현실이다. 이런 문제점을 해결하기 위하여 집중소자(lumped element)인 R L C를 탄성 표면파 듀플렉서 대신 스위치 모들에 적용하게 된다면 여러 가지 다양한 형태의 회로를 구현할 수 있고 회로망 내에 위치하는 집중소자의 정격을 최적화하여 스위치 모듈의 성능을 향상시킬 수 있는 가능성이 있다. 본 연구에서는 $900 MHz{\sim}2.2 GHz$의 대역에서 소형화 집적화에 적용 가능한 디바이스를 개발하기 위하여 고주파, 저진압, 저손실 스위치 모듈의 제조와 구성되는 커패시터와 인덕터의 제조와 특성에 관하여 연구하였다.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.10
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• pp.1303-1310
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• 1999

In this paper, the Timed Petri-Nets(TPN) modeling of Modular Cell Manufacturing Systems(MCMS) was investigated to overcome the limit of batch mode operation, which has been one of the most popular manufacturing types to produce an extensive industrial output and to be able to adopt to suitable and quickly changing manufacturing environments. A model of the MCMS was developed in reference to the actual TFT-LCD manufacturing system. TFT-LCD manufacturing system is not mass-productive in batch mode, but it operates in the form of MCMS which consists of a sequence of several cells with four processes of operation, including those of color filter(C/F), TFT, cell, and module. The cell process is further regrouped in those of Front-End and Back-End. For the Back-End cell process, it is reconstructed into a virtual model, consisting of three cells. The TPN modeling encompasses those properties, such as states and operations of machines, the number of buffers, and the processing time. The performance of the modeling was further examined in terms of scheduling system. The productivity in each cells was examined with respect to the change of failure rate of the cell machines and Automatic Guided Vehicles(AGV) using simulation by TPN.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.5A
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• pp.519-527
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• 2010

In this paper, we design and implement a broadband LNA(Low Noise Amplifier), a mixer, and oscillators in RF module part for radar detector. For resolving the limitation of the conventional product that the sensitivity is low due to the poor gain flatness, we propose the architecture of RF module part. The proposed RF module part is composed with a broadband 2-stage LNA, a mixer, and three oscillators, and improves the maximum gain and gain flatness for detecting various frequencies. The overall performances of RF module part are above 38 dB conversion gain in whole band and 1 dB gain flatness. These results show that the maximum gain which is the problem of the conventional product is improved 6 dB from 35 dB to 41 dB, and gain flatness is also improved 17 dB from 22 dB to 5 dB.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.4
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• pp.51-56
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• 2014

Thesedays, there are many smart device applications developed, especially on the using various sensors included in the smart device. Smart devices have several sensors which are camera, GPS, mike, and communication module for collecting ubiquitous environment, and many applications are developed by using such sensors. In this paper, we developed the multimedia stream architecture and examined the smart device applications based on open source with front and back-end server clouds for developing the conceptual architecture. Also, we examined the back-end distributed servers, realtime multimedia stream transferring, multi-media store, and media relay for other server and smart devices. We test the examined architecture on the real target environment to collect the SIP initial setup time, media stream delay, and end-to-end play time. The test results show that there have good network operation environment to provide realtime multimedia services, and we need to improve the end-to-end play time by minimizing the initial setup time.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.1
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• pp.115-121
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• 2004

In this paper, a new distributed intelligent control module based on LonWoks fieldbus for air handling unit(AHU) of heating, ventilating and air-conditioning(HVAC) is proposed to replace with a conventional direct digital control(DDC) system with 32 bit microprocessor. The proposed control architecture has a excellent features such as highly compact and flexible function design, a low priced smart front-end and reliable performance with various functions. This also addresses issues in control network configuration, logical design of field devices by S/W tool, Internet networking and electronic element installation. Experimental results for showing the system performance are also included in this paper.

• ETRI Journal
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• v.34 no.2
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• pp.216-225
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• 2012

This paper presents a transceiver module for human body communications whereby a spread signal with a group of 64 Walsh codes is directly transferred through a human body at a chip rate of 32 Mcps. Frequency selective digital transmission moves the signal spectrum over 5 MHz without continuous frequency modulation and increases the immunity to induced interference by the processing gain. A simple receiver structure with no additional analog circuitry for the transmitter has been developed and has a sensitivity of 250 ${\mu}V_{pp}$. The high sensitivity of the receiver makes it possible to communicate between mobile devices using a human body as the transmission medium. It enables half-duplex communication of 2 Mbps within an operating range of up to 170 cm between the ultra-mobile PCs held between fingertips of each hand with a packet error rate of lower than $10^{-6}$. The transceiver module consumes 59 mA with a 3.3 V power supply.

• Proceedings of the KIEE Conference
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• 2003.07d
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• pp.2239-2241
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• 2003

A new RF control system of Pohang Accelerator Laboratory (PAL) storage ring is a subsystem upgraded PAL control system, which is based upon Experimental Physics and Industrial Control System (EPICS). There are 5 control components, Low Level RF System (LRS), Klystron System, Circulator System, Cavity System, Local Cooling Water System (LCW) at the storage ring of PAL. The new RF control system for the storage ring has been under development for one years, first versions of individual VME (Versa Module Europa) Input/output modules under construction and system integration begun. In this system, VMEbus-based hardware is widely used for front-end controllers (FDS), Input/output controller (IOC). A number of Programmable Logic Controller (PLC) and SUN workstations are also used for Operator Interfaces (OPI) in the control system. This paper describes the development VME I/O module to the new control system and how the design of this new system.

• Journal of electromagnetic engineering and science
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• v.18 no.3
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• pp.188-198
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• 2018

In this study, we propose an approach for the design and satisfy the requirements of the fabrication of a small, lightweight, reliable, and stable ultra-wideband receiver for millimeter-wave bands and the contents of the approach. In this paper, we designed and fabricated a stable receiver with having low noise figure, flat gain characteristics, and low noise characteristics, suitable for millimeter-wave bands. The method uses the chip-and-wire process for the assembly and operation of a bare MMIC device. In order to compensate for the mismatch between the components used in the receiver, an amplifier, mixer, multiplier, and filter suitable for wideband frequency characteristics were designed and applied to the receiver. To improve the low frequency and narrow bandwidth of existing products, mathematical modeling of the wideband receiver was performed and based on this spurious signals generated from complex local oscillation signals were designed so as not to affect the RF path. In the ultra-wideband receiver, the gain was between 22.2 dB and 28.5 dB at Band A (input frequency, 18-26 GHz) with a flatness of approximately 6.3 dB, while the gain was between 21.9 dB and 26.0 dB at Band B (input frequency, 26-40 GHz) with a flatness of approximately 4.1 dB. The measured value of the noise figure at Band A was 7.92 dB and the maximum value of noise figure, measured at Band B was 8.58 dB. The leakage signal of the local oscillator (LO) was -97.3 dBm and -90 dBm at the 33 GHz and 44 GHz path, respectively. Measurement was made at the 15 GHz IF output of band A (LO, 33 GHz) and the suppression characteristic obtained through the measurement was approximately 30 dBc.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.11
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• pp.2391-2396
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• 2010

The power-controlled six-port element that can control the local oscillator signal power and receiving RF signal power was designed and implemented in this paper. The direct conversion six-port element configuration was proposed, which provides the constant six-port output power by controlling the six-port input power with various signal strength. The direct conversion six-port element protects the power detector element of six-port receiver from the saturation status and compensates the transmission performance degradation. For implementation of power-controlled six-port element, the power-controlled six-port element including the power controller was analyzed. The implemented power-controlled six-port element shows the power control capability of 36 dB and gain imbalance of about 1.6 dB, phase imbalance of about $4^{\circ}$ in the frequency range of 1.69 GHz. The measured results show the good performance as direct conversion front-end element.