• JSTS:Journal of Semiconductor Technology and Science
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• 제4권3호
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• pp.182-188
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• 2004

We demonstrate a $2.1\;{\times}\;1.0\;{\times}\;0.1cm^3$ sized compact transmitter using LTCC System-in-Package (SiP) technology for 60GHz-band wireless communication applications. For low-attenuation characteristics and resonance suppression of the SiP, we have proposed and demonstrated a coplanar double wire-bond transition and novel CPW-to-stripline transition integrating air-cavities as well as novel air-cavities embedded CPW line. The fabricated transmitter achieves an output of 13dBm at a RF frequency of 62GHz, an IF frequency of 2.4GHz, and a LO frequency of 59.6GHz. The up-conversion gain is 11dB, while the LO signal is suppressed with the image rejection mixer below -21.4dBc, and the image and spurious signals are also suppressed below -31dBc.

• Transactions of the Korean Society of Automotive Engineers
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• 제10권5호
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• pp.23-28
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• 2002

As the interest on the air pollution is gradually rising up at home and abroad, automotive industries have been working on the exhaust emission reduction from vehicles through a lot of approaches, which consist of new engine design, innovative aftertreatment systems, and using clean fuels. Methanol, ethanol, LNG, LPG, H2, reformulated gasoline are generally recognized as the clean fuel. Since the low price policy of government on LPG has expanded its vehicle market recently, there is concern of the exhaust emission of LPG vehicle. In this paper, we studied the value of LPG fuel as a clean fuel by comparing the results of the exhaust emission from LPG and Gasoline fueled vehicles, and discussed its limitation of LPG vehicle with mixer type as a fuel supply system. FTIR was used to understand the difference of exhaust emission components of LPG and Gasoline fueled vehicles.

• Journal of Industrial Technology
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• 제29권B호
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• pp.139-144
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• 2009

A Doppler radar is a radar using the doppler effect of the returned echoes from targets to measure their radial velocity. To be more specific the microwave signal sent by the radar antenna's directional beam is reflected toward the radar and compared in frequency, up or down from the original signal, allowing for the direct and highly accurate measurement of target velocity component in the direction of the beam. In this paper, we designed the doppler radar composed of 10.5 GHz band DROs(Dielectric Resonator Oscillator), $90^{\circ}C$ branch line coupler, single balanced mixer and $4{\times}4$ array antenna of high gain, high directivity, for non-contact type hydrometer. Fabricated Doppler radar can detect slow moving objects.

• Journal of Sensor Science and Technology
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• 제13권2호
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• pp.133-138
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• 2004

Today, the obstacle detection system has massive size and restrictive detection range. To solve these problems, this paper proposes the capacitance variation detector using the variated capacitance value as a result of the obstacle approaching. If obstacle approaches, the capacitance value of capacitance sensor is increased and the operating frequency of oscillator is decreased. Then this changed frequency appears to the output of the mixer that operate down conversion. The capacitance variation detector is produced by Hynix$0.35{\mu}$ CMOS process. In experiment result, the frequency of final output is 6.81 MHz at no obstacle and 31.45 MHz at approaching obstacle. In conclusion, proposed capacitance variation detector has small size, low power consumption and easiness to set up anywhere. So it is expected to substitute the obstacle detector.

• Proceedings of the SAREK Conference
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• 대한설비공학회 2008년도 하계학술발표대회 논문집
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• pp.1019-1024
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• 2008

A 3 MW class oxy-fuel boiler has been developed to capture $CO_2$ from the exhaust gas. The system is a scale-up of the previous 0.5 MW class system in general. A heat exchanger and a mixer are additionally installed to stabilize the flame for the FGR mode. The system yields the exhaust gas with $CO_2$ concentration over 90% and reduced NO emission to 1/10 of conventional air combustion system.

• Journal of electromagnetic engineering and science
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• 제8권1호
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• pp.17-22
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• 2008

It is presented that sampling rates for behavioral modeling of quasi-memory less nonlinear devices can be far less than the Nyquist rate of the input signal. Although it has been believed that the sampling rate of nonlinear device modeling should be at least the Nyquist rate of the output signal, this paper suggests that far less than the Nyquist rate of the input signal can be applied to the modeling of quasi-memoryless nonlinear devices, such as frequency multipliers. To verify, a QPSK signal at 820 MHz were applied to a frequency tripler, whereby the device can be utilized as an up-converting mixer into 2.46 GHz with the aid of digital predistortion. AM-AM, AM-PM and PM-PM can be successfully measured regardless of sampling rates.

• Transactions of the Korean Society of Automotive Engineers
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• 제11권4호
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• pp.7-14
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• 2003

Recently, LPG has been considered as more environmental friendly fuel than liquid fuels for vehicles. However because LPLi engine has the strong point that not only increases the volumetric efficiency and cold startability, but also decreases unburned hydrocarbon exhaust emission in warm-up condition, much attention has moved to development of the Liquid Phase LPG injection (LPLi) system from the mixer type LPG engine. To reduce exhaust NOx, this study investigated the effect of EGR with LPLi engine and determined optimized EGR feeding position and distribution. In addition, engine stability, performance, and exhaust emission level were evaluated.

• Journal of Korean Port Research
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• 제9권1호
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• pp.65-72
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• 1995

This study is being done for the purpose to achieve a stable demand and supply of materials for long term. The author investigated condition of suitable mixer design method for concrete, an individual value and a character of dynamics as a supplement material by drying up the natural aggregate, and a possible practicalization plan to reduce defects to the minimum. As a result of this study, it can be acquired a good quality of concrete by the use of the natural sand (Nak Dong river sand) and the crushed sand with suitable mixing ratio. The fineness modulus (F.M) of mixing aggregate is $2.7\pm1$ at this time and this is good for workbility and plasticity of concrete.

• KSCE Journal of Civil and Environmental Engineering Research
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• 제26권4A호
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• pp.761-766
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• 2006

Polymer composite are increasingly considered as structural components for use in civil engineering, on account of their enhanced strength-to-weight ratios. Unsaturated polyester (UP) resin have been widely used for the matrix of composites such as FRP and polymer composite, due to its excellent adhesive. Polymer nanocomposites are new class of composites derived from the nano scale inorganic particles with dimensions typically in the range of 1 to 1000 nm that are dispersed in the polymer matrix homogeneously. Owing to the high aspect ratio of the fillers, mechanical, thermal, flame, retardant and barrier properties are enhanced without significant loss of clarity, toughness or impact strength. To prepare the MMT (Montmorillonite)-UP exfoliated nanocomposites, UP was mixed with MMT at $60^{\circ}C$ for 3 hours by using pan mixer. XRD (X-ray diffraction) pattern of the composites and TEM (Transmission Electron Micrographs) showed that the interlayer spacing of the modified MMT were exfoliated in polymer matrix. The mechanical properties also supported these findings, since in general, tensile strength, modulus with modified MMT were higher than those of the composites with unmodified MMT. The thermal stability of MMT-UP nanocomposite is better than that of pure UP, and its glass transition temperature is higher than that of pure UP. The polymer concrete made with MMT-UP nanocomposite has better mechanical properties than of pure UP. Therefore, it is suggested that strength and elastic modulus of polymer concrete was found to be positively tensile strength and tensile modulus of the MMT-UP nanocomposites.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• 제15권5호
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• pp.480-485
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• 2004

In this paper, a new predistortion linearizing method using frequency up-conversion operation of mixer is proposed. This linearizing method doesn't require any additional signal sources in spite of frequency up-conversion mixing operation. This method extracts the 2nd low frequency intermodulation distortion signal from input signals and uses the extracted 2nd low frequency intermodulation distortion signal as mixing signal source. To show validation of the proposed predistortion method, we made K-PCS power amplifier. On 2-tone signals amplification process, the (C/I) ratio of amplifier is improved 26 ㏈ (@Po=22 ㏈m/tone), where two tones are 1.8544 ㎓ and 1.8556 ㎓, respectively. And (C/I) ratio is improved more than to 20 ㏈ for 17 ㏈ output signal dynamic range. On IS-95A CDMA 1FA amplification process, the improvements of adjacent channel power ratio(ACPR) are 10.8 ㏈ and 6.4 ㏈ at ${\pm}$885 ㎑ and ${\pm}$1.25 ㎒ offset points, respectively.