• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.3 s.333
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• pp.33-38
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• 2005

In this paper, we have designed and fabricated a hybrid ring coupler to prove the fabrication possibility of various passive components, applying millimeter wave using newly proposed transmission lines, i.e. BAMLs. The characteristics of the fabricated hybrid ing coupler were a the S31(coupling) of 3.58 dB, the S21(thru) of 3.31 dB at the 60 GHz center frequency, the S11(return loss) over 16.17 dB, S41(isolation) over 55 dB at 61 GHz, and the phase difference between port 2 and port 3 of $180{\pm}loat$ 60GHz. In order to reduce the size of hybrid ring coupler, we designed the hybrid ring coupler which inserts a slow wave structure. With this structure, we were able to reduce the hybrid ring coupler by $33\%$ area.

• Journal of the Institute of Electronics Engineers of Korea TE
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• v.42 no.2
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• pp.23-28
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• 2005

This study was to suggest the propagation path loss and predictive model of propagation path analysis in order to apply the frequency in the millimeter-wave band to the real time inter-vehicle communication system. This study was to suppose the case of inter-vehicle communication on the one-way two-lanes road in the big cites with a lot of traffic jams in order to analyze the effect by the reflected wave of multipath. As a simulation of suggested model, it found out that the propagation path by the reflected wave was about 0.1[m]$\sim$5.1[m] longer than the one by the direct wave during the transmission of 100[m] wave direct path. Also, as a result of comparing the propagation path loss, the loss would be about -0.8[dB]$\sim$-4.2[dB] larger in case of wall reflection and -0.8[dB]$\sim$-1[dB] vehicle reflection. From the result above, this researcher found out that the path loss of reflected wave produced by the walls was about -3.2[dB] larger than the path loss produced by the adjacent vehicles.

• International Journal of Fluid Machinery and Systems
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• v.2 no.2
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• pp.156-164
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• 2009

This paper aims to describe the importance of data, data collection methods, parameters to estimate the potential of wave energy and environmental impacts. The technical and economical status in wave energy conversion is outlined. Power and energy efficiency relationships are discussed. Many different types of wave-energy converters have been detailed. The progress in wave energy conversion in Malaysia is reviewed.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.8
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• pp.105-111
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• 2004

In this paper, millimeter-wave high gain and broadband MHEMT cascode amplifiers were designed and fabricated. The 0.1 ${\mu}{\textrm}{m}$ InGaAs/InAlAs/GaAs Metamorphic HEMT was fabricated for cascode amplifiers. The DC characteristics of MHEMT are 640 mA/mm of drain current density, 653 mS/mm of maximum transconductance. The current gain cut-off frequency(f$_{T}$) is 173 GHz and the maximum oscillation frequency(f$_{max}$) is 271 GHz. By using the CPW transmission line, the cascode amplifier was designed the matched circuit for getting the broadband characteristics. The designed amplifier was fabricated by the MHEMT MIMIC process that was developed through this research. As the results of measurement, the 1 stage amplifier obtained 3 dB bandwidth of 37 GHz between 31.3 to 68.3 GHz. Also, this amplifier represents the S21 gain with the average 9.7 dB gain in bandwidth and the maximum gain of 11.3 dB at 40 GHz. The 2 stage amplifier has the broadband characteristics with 3 dB bandwidth of 29.5 GHz in the frequency range from 32.5 to 62.0 GHz. The 2 stage cascode amplifier represents the high gain characteristics with the average gain of 20.4 dB in bandwidth and the maximum gain of 22.3 dB at 36.5 GHz.z.z.

• Journal of the Korean Magnetics Society
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• v.24 no.6
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• pp.165-170
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• 2014

We analyzed the ferromagnetic and spin wave resonance signals measured in amorphous CoFeB thin films with different thickness. The ferromagnetic resonance field ($H_{FMR}$) was not depend on the thickness of CoFeB films, but the spin wave resonance field ($H_{SWR}$) was well fitted with the theoretical prediction depending on the thickness. The uniaxial anisotropy field of $H_k$ = 37 Oe was obtained from the angular dependent $H_{FMR}$ in CoFeB films. The $H_{SWR}$ showed same angular behaviors with $H_{FMR}$, however, the amplitude of spin wave resonance signals showed 5.7 times higher than that of ferromagnetic resonance signals in CoFeB film with t = 100 nm. The higher signals were due to the two reasons; one was the small damping for the spin wave propagation without degradation, the other was uniform magnetization for the ideal standing wave modes.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.5 s.335
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• pp.55-60
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• 2005

A V-band MIMIC quadruple subharmonic mixer is reported in this paper. The cascode harmonic generator is proposed for a high conversion gain. The proposed cascode harmonic generator is shown with a 4-th harmonic output characteristic that represents an average of 2.9 dB and a maximum of 4 dB higher than the conventional multiplier. The measured result of the subharmonic mixer has a conversion gain of 3_4 dB which a good conversion gain at a LO power of 13 dBm. Isolations of LO-to-IF and LO-to-RF were obtained -53.6 dB and -46.2 dB, respectively. The conversion gain of the subharmonic mixer in this study has a higher conversion gain compared with some other reports in millimeter-wave range.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.9
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• pp.18-24
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• 2007

We report broadband cascode amplifiers of a single-ended and a balanced amplifier for the millimeter-wave applications. The amplifiers were fabricated using 0.1 ${\mu}m\;{\Gamma}-gate$ PHEMT technology on GaAs substrate. The single-ended cascode amplifier was designed and fabricated by using shunt peaking technology. The fabricated single-ended cascode amplifier shows 3 dB bandwidth of 37 GHz($18.5{\sim}55.5$ GHz) and the maximum $S_{21}$ gain of 9.38 dB. The balanced cascode amplifier using tandem couplers achieves 3 dB bandwidth and the maximum $S_{21}$ gain of 44.5 GHz($21{\sim}65.5$ GHz) and 10.4 dB at 60 GHz, respectively. The 3 dB bandwidth of the balanced cascode amplifier shows 20% lager than the single-ended cascode amplifier.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.925-928
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• 2005

In this study, we fabricated the DAMLs using surface micromachining technology as well a low loss coupler for the millimeter-wave band applications using these DAMLs. The structure of DAML is that a signal line is supported on ground plane by dielectric posts. Therefore it has advantages about the loss characteristic and the stable structure. The other advantage of the DAML process is a simple and convenient technique using 4 mask steps, even if it has a micromachining technology. The lowest loss of the fabricated DAML was obtained 2.2 dB/cm at 110 GHz. To obtain the low loss characteristic, couplers were designed and fabricated by using DAMLs. The fabricated ring hybrid coupler has the coupling of 3.58 dB and the thru of 3.31 dB at 60 GHz. We can also obtain the coupling of 3.42 dB, the thru of 3.82 dB from fabricated branch line coupler at 60 GHz.

• JSTS:Journal of Semiconductor Technology and Science
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• v.5 no.3
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• pp.210-219
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• 2005

We report on a low-cost V-band wireless transceiver with no use of any local oscillator in the receiver block using a self-heterodyne architecture. V-band millimeter-wave monolithic IC (MMIC) modules were developed to demonstrate the wireless transceiver using coplanar waveguide (CPW) and GaAs PHEMT technologies. The MMIC modules such as the MMIC low noise amplifier (LNA), medium power amplifier (MPA) and the up/down-mixer were installed in the transceiver system. To interface the MMIC chips with the component modules for the transceiver system, CPW-to-waveguide fin-line transition modules of WR-15 type were designed and fabricated. The fabricated LNA modules showed a $S_{21}$ gain of 8.4 dB and a noise figure of 5.6 dB at 58 GHz. The MPA modules exhibited a gain of 6.9 dB and a $P_{1dB}$ of 5.4 dBm at 58 GHz. The conversion losses of the up-mixer and the down-mixer module were 14.3 dB at a LO power of 15 dBm, and 19.7 dB at a LO power of 0 dBm, respectively. From the measurement of V-band wireless transceiver, a conversion gain of 0.2 dB and a $P_{1dB}$ of 5.2 dBm were obtained in the transmitter block. The receiver block showed a conversion gain of 2.1 dB and a $P_{1dB}$ of -18.6 dBm. The wireless transceiver system demonstrated a successful data transfer within a distance of 5 meters.

• Korean Journal of Clinical Laboratory Science
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• v.38 no.3
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• pp.224-230
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• 2006

Up to now, there have been rare clinical studies on leaders and aerobics athletes. To get the useful data for protecting from auditory disorder, we selected 15 female aerobics leaders (experimental group) and 15 females (control group) unexperienced in aerobics and a without neurological and octolaryngological disorder. The average age was $34.87{\pm}8.80$ (experimental group) and $34.07{\pm}8.45$ (control group) years, and the average career of an aerobics leader (experimental group) was $8.33{\pm}4.73$ years. We measured the auditory evoked potential (AEP) of the two groups treated with 70, 75 and 85 dB intensity from January 2006 to May 2006 and analyzed the absolute latency (AL) and interpeak latency (IPL) by the SPSS/pc+ 12.0 program. In the comparison of the AL between the experimental group and the control group according to intensity, both ears treated with 70 and 75 dB had a significant difference (p<0.05) in the I, III, V wave and in the I, V wave respectively, and the experimental group treated with 85 dB showed a difference in the I, III, V wave (left ear) and in the I wave (right ear) respectively. The IPL of the two groups treated with various intensities had no prolongation. In the comparison of the AL between the experimental group and the control group according to ages, the experimental group in their 20s treated with 70 dB showed a significant difference (p<0.05) in the V wave (left ear) and in the I, III, V wave (right ear), and the experimental group in their 20s treated with 75 dB in the I, III wave (left ear) and in I, III, V wave (right ear), and experimental group in their 20s treated with 85 dB in the V wave (left ear) and in the III, V wave (right ear). The experimental group in their 30s treated with 70 dB had a significant difference (p<0.05) only in the V wave (right ear). Only in the IPL of subjects in their 20s treated with 85 dB, III-V and I-V of both ears was extended. In the comparison of the AL and IPL according to career, there was no significant difference between the two groups. From this results, we concluded that the lower sound intensity (70 dB) showed a more significant difference in the experimental group than the control group. We concluded that the leader of aerobics exposed to louder sounds than normal people are affected by auditory neurological and octolaryngological disorders. So we think that the leaders of aerobics need to control the noise level for protecting themselves against a disease.