• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2000.11a
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• pp.225-228
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• 2000

In this paper, the design for a low noise amplifier with the EM simulation is presented. The ATF36077 pHEMT device is applied to design LNA for U-NII frequency band (5 GHz ～ 6 GHz). The matching networks have been designed by the only open ended stub in order to reduce parasitic effects generated from a via structure. Through EM simulator, the simulation result shows that the linear gain (@5.5 GHz) is over 10 dB, input return loss and output return loss (@ 5.5 GHz) are a below 10 dB respectively, and the 3rd order intercept point is about 17 dBm.

• ETRI Journal
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• v.45 no.4
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• pp.581-593
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• 2023

This paper proposes four-ring slot resonator-based MIMO antennas of 75×150 mm² without and with CSRR structures in the sub-6-GHz range. These orthogonal-fed antennas have shown diverse characteristics with dual polarization. L-shaped parasitic structures have increased the isolation (i.e., >40 dB) in the single-element antenna over the band of 3.4 GHz-3.8 GHz. A set of three CSRR structures in the MIMO antenna reduced the coupling between antenna ports placed in an inline arrangement and enhanced the isolation from 12 dB to 20 dB and the diversity characteristics. The S-parameters of both MIMO antennas are measured and used to evaluate MIMO parameters like ECC, TARC, MEG, and channel capacity loss. The simulation results show the variations in the gain and directivity on exciting linear and dual polarizations. The diversity performance of the reported MIMO antennas is suitable for 5G applications.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.8
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• pp.730-738
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• 2009

In this paper, we present a equivalent circuit considered parasitic elements about LTCC multi-layer BPF structure that was studied previously and a process of extraction of the element value using SOC technique. By applying extracted element values to equivalent circuit, 2th LTCC filter was designed and fabricated that was applied to satellite DMB. The filter was fabricated of Dupont951 substrate with relative permittivity of 7.8, the dimension of the fabricated filter is $2.4{\times}3.8{\times}0.378mm^3$. The measurement results indicate 1.4 dB of insertion loss and 32.3 dB of return loss, which are in good agreement with simulated ones.

• The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
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• v.35 no.4
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• pp.47-62
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• 2022

Objectives : To analyze and understand the clear meaning of Nochae(勞瘵), which is used in the same meaning as tuberculosis in Korean medicine. Methods : Nochae was mainly investigated using the Korean medicine classic DB(https://mediclassics.kr). Records that clearly revealed the visual observation of Nochaechung(勞瘵蟲), the cause of Nochae, and those that do not were arranged in chronological order. It was also analyzed what modern diseases are similar to Nochae. Results : Records that Nochaechung can be observed visually through feces or vomiting suggested the possibility of ascariasis. Nochaechung, which has a shape similar to silkworms and causes symptoms such as coughing and hemoptysis similar to those of tuberculosis while parasitic on human, suggested the possibility of paragonimus westermani. Based on the record that it showed symptoms of coughing and hemoptysis along with chills, fever, and weight loss, Nochae might have been a disease such as pneumonia and lung cancer as well as tuberculosis. Records of women's bloating, weight loss, anorexia, and jaundice suggested that Nochae might have been a liver cirrhosis. Conclusions : Records that clearly reveal the visual observations of Nochaechung, suggested that Nochae was a parasitic disease such as ascariasis or paragonimiasis. Records that visual observation of Nochaechung was not clearly revealed, suggested that Nochae might have been diseases such as pneumonia, lung cancer, and liver cirrhosis in addition to tuberculosis.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.217-221
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• 2001

This paper presents a new prototype of soft-switching DC-DC power converter with a high frequency transformer link which has two active power controlled switches in full bridge rectifier with capacitor input type smoothing filter. In this DC-DC converter, ZVS of the inverter in transformer primary side and ZCS of active rectifier area in secondary side can be completely achieved by taking advantage of parasitic inductor component of high-frequency transformer and loss less snubbing capacitors. Its operation principle and salient features are described. The steady-state operating characteristics of the proposed DC-DC power converter are illustrated and discussed on the basis of the simulation results in addition to the experimental ones obtained by 2kw-40kHz power converter breadboard set up.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.12 no.3
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• pp.114-123
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• 1998

The multi-resonant converter(MRC) minimizes a parasitic oscillation by using the resonant tank circuit absorbed parasitic reactances existing in a converter circuit. So it si possible that the converter operated at a high frequency has a high efficiency because the losses are reduced. Such a MHz high frequency applications provide a high power density [W/inch3] of the converter. But the resonant voltage stress across a switch of the resonant tank circuit is 4~5 times a input voltage. This h호 voltage stress increases the conduction loss because of on-resistance of a MOSFET with higher rating. Thus, in this paper we proposed the alternated multi-resonant converter (AT MRC) differ from the clamp mode multi-resonant converter and applicated it to the forward MRC. The AT forward MRC can reduce the voltage stress to 2~3 times a input voltage by using two series input capacitor. The control circuit is simple because tow resonant switches are driven directly by the output pulse of the voltage controled oscillator. This circuit type is verified through the experimental converter with 48V input voltage, 5V/50W output voltage/power and PSpice simulation. the measured maximum voltage stress is 170V of 2.9 times the input voltage and the maximum efficiency of 81.66% is measured.

• Proceedings of the KIEE Conference
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• 1999.07f
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• pp.2698-2700
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• 1999

The MRC minimizes a parasitic oscillation using the resonant tank circuit absorbed parasitic reactances existing in a converter circuit. So the converter is capable of operating at a high switching and also reducing the losses. But the resonant voltage stress across a resonant switch is 4-5 times a input voltage. This high voltage stress increases the conduction loss in MOSFET. In this paper, the CM forward MRC with synchronous rectifier and AT forward MRC are compared about efficiency and semiconductor stress. For analysis, we have built a 50W CM forward MRC and a 50W AT forward MRC. in which the input voltage is 48V, output voltage is 5V, each other. The measured voltage stress is about 170V of 2.9 times the input voltage in the AT Forward MRC, about 106V of 1.8 times the input voltage in CM forward MRC, and the efficiency is 81.05% in AT Forward MRC, 83.61% in CM forward MRC.

• JSTS:Journal of Semiconductor Technology and Science
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• v.8 no.4
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• pp.289-294
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• 2008

A 77 GHz 3-stage low noise amplifier (LNA) employing one common source and two cascode stages is developed using $0.13{\mu}m$ CMOS process. To compensate for the low gain which is caused by lossy silicon substrate and parasitic element of CMOS transistor, positive feedback technique using parasitic inductance of bypass capacitor is adopted to cascode stages. The developed LNA shows gain of 7.2 dB, Sl1 of -16.5 dB and S22 of -19.8 dB at 77 GHz. The return loss bandwidth of LNA is 71.6 to 80.9 GHz (12%). The die size is as small as $0.7mm\times0.8mm$ by using bias line as inter-stage matching networks. This LNA shows possibility of 77 GHz automotive RADAR system using $0.13{\mu}m$ CMOS process, which has advantage in cost compared to sub-100 nm CMOS process.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.5
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• pp.713-721
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• 2001

In this paper, parasitic patches gap-coupled microstrip antenna and stacked microstrip patch antenna combined with parallel coupled lines, which are a kind of wideband impedance matching network, are proposed to get the wider bandwidth. The iterative method using a distributed network is proposed to design the parallel coupled lines as a wideband impedance matching network. Measurements show that the proposed antennas provide wider bandwidths ~1.6 times and ~1.5 times those of conventional parasitic gap-coupled microstrip patch antenna and stacked microstrip patch antenna. In addition, measured radiation patterns show no serious variation of radiation patterns though the parallel coupled lines is added. The antenna gain is, however, lowered about 1 dB and 0.5 dB by the coupling loss in the parallel coupled lines.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.32 no.5
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• pp.359-366
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• 2008

A two-dimensional thermal model of proton exchange membrane fuel cell with large active area is developed to investigate the performance of fuel cell with large active area over various thermal management conditions. The core sub-models of the two-dimensional thermal model are one-dimensional agglomerate structure electrochemical reaction model, one-dimensional water transport model, and a two-dimensional heat transfer model. Prior to carrying out the simulation, this study is contributed to set up the operating temperature of the fuel cell with large active area which is a maximum temperature inside the fuel cell considering durability of membrane electrolyte. The simulation results show that the operating temperature of the fuel cell and temperature distribution inside the fuel cell can affect significantly the total net power at extreme conditions. Results also show that the parasitic losses of balance of plant component should be precisely controlled to produce the maximum system power with minimum parasitic loss of thermal management system.