• Proceedings of the KSME Conference
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• 2002.08a
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• pp.597-600
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• 2002

In general, the function of intake structure, whether it be a open channel, a fully wetted tunnel, a sump or a tank, is to supply an evenly distributed flow to a pump station. An even distribution of flow, characterized by strong local flow, can result in formation of surface or submerged vortices, and with certain low values of submergence, may introduce air into pump, causing a reduction of capacity and efficiency, an increase in vibration and additional noise. Uneven flow distribution can also increase or decrease the power consumption with a change in total developed head. To avoid these sump problems pump station designers are considered intake structure dimensions, such as approaching upstream, baffle size, sump width, width of pump cell and so on. From this background, flow characteristics of intake within sump are Investigated numerically to obtain the optimal sump design data. The sump model is designed in accordance with HI code.

• Proceedings of the IEEK Conference
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• 2003.07a
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• pp.270-273
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• 2003

The design, fabrication, and measured result of a 4.7 GHz differential VCO (Voltage Controlled Oscillator) for a 5.2 GHz WLAN (Wireless Local Area Network) applications is presented. The circuit is designed in a 0.35 mm technology employing three metal layers. The design is based on a fully integrated LC tank using spiral inductors. Measured tuning range is 10% of oscillation frequency with a control voltage from 0 to 3.0 V. Oscillation power of $\square$ 2.3 dBm at 4.63 GHz is measured with 21 mA DC current at 3V supply. The phase noise is $\square$ 104.17 dBc/Hz at 1 MHz offset.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.4
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• pp.318-323
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• 2004

When a strong electric field is applied between a sharply curved electrode and a blunt surface, the corona may result in a gas movement in the electrode gap which is directed toward the blunt surface. That is called the corona wind. It enhances heat and mass transfer between the surface and the surrounding gas. Moreover such enhancement causes no noise or vibration, which can be applied in complex, isolated geometries, and allows simple control of surface temperatures. This paper examines the relationship between the corona wind and the relative humidity. The facility consists of high voltage power supply thin tungsten wire, plate electrode, multimeter, microammeter and flow meter. Gas velocity is a linear function of voltage, relative humidity and is proportional to the square root of the current. The maximum velocities for the positive and negative corona discharge are 1.9 m/s (2.74 CMM/m), 1.5 m/s(2.15 CMM/m), respectively.

• JSTS:Journal of Semiconductor Technology and Science
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• v.15 no.2
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• pp.202-207
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• 2015

A CMOS relaxation oscillator, with high robustness over process, voltage and temperature (PVT) variations, is designed in $0.18{\mu}m$ CMOS. The proposed oscillator, consisting of full-differential charge-discharge timing circuit and switched-capacitor based voltage-to-current conversion, could be expanded to a simple open-loop frequency synthesizer (FS) with output frequency digitally tuned. Experimental results show that the proposed oscillator conducts subcarrier generation for frequency-modulated ultra-wideband (FM-UWB) transmitters with triangular amplitude distortion less than 1%, and achieves frequency deviation less than 8% under PVT and phase noise of -112 dBc/Hz at 1 MHz offset frequency. Under oscillation frequency of 10.5 MHz, the presented design has the relative FS error less than 2% for subcarrier generation and the power dissipation of 0.6 mW from a 1.8 V supply.

• 한국정보통신설비학회:학술대회논문집
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• 2006.08a
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• pp.205-207
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• 2006

In this paper, we present a design procedure of high linearity LNA using CMOS technology. To enhance the low linearity of the inherent CMOS transistor, we adopt the modified derivate superposition with adding external capacitor. The simulation of the designed LNA shows $IIP_3$ of +12-dBm, power gain of 13.8-dB, noise figure of 1.75-dB over the 900 MHz UHF RFID frequencies. The circuit draws the current of 4.2 mA from 1.8-V supply voltage.

• Journal of ILASS-Korea
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• v.7 no.2
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• pp.31-36
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• 2002

According to the improvement of PC performance, it is expected that calorific value, which causes PC to malfunction, is increased. Therefore, the development of new cooling system is recently required. As the method to solve this problem, we applied loop heat pipe to PC cooling system. The advantage of the loop heat pipe is that it has a small size, light weight, simple shape, long life and it has a good performance on heat transfer, no-noise, wide range of applicable temperature and no supply of power from the outside. It is confirmed that loop heat pipe reduces thermal resistance and has a good performance on PC cooling.

• Proceedings of the IEEK Conference
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• summer
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• pp.218-220
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• 2004

A new wide-band VCO topology using Miller capacitance is proposed. Contrary to conventional VCO using the Miller capacitance where the variable amplifier gain is negative, the proposed VCO uses both the negative and positive variable amplifier gain to enhance the frequency tuning range significantly. The proposed VCO is simulated using HSPICE. The simulations show that 410MHz and 220MHz frequency tuning range are obtained using the negative .and positive variable amplifier gain, respectively. The tuning range of the proposed VCO is $23\%$ of the center frequency(2.8GHz). The phase noise is -104dBc/Hz at 1MHz offset by simple model. The operating current is only 3.84mA at 2.5V power supply.

• Journal of the Korea Institute of Military Science and Technology
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• v.15 no.5
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• pp.543-549
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• 2012

Hybrid electric propulsion systems are expected as future primary combat platforms because the systems can supply enough electric power, easily locate components inside vehicles, and maneuver without undesired noise. However, increasing electric/electronic/software usage causes abnormal failure patterns which have not been noticeable in conventional automotive. Recently, the functional safety standard for road vehicles were enacted and vehicle manufacturers request their components which satisfy standardized quality. This research analyzes functional safety standards(IEC 61508 and ISO 26262) and compares the standards for road vehicles with military standards of system safety. Strategies to apply functional safety in the combat hybrid electric vehicle are scrutinized.

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.1776-1778
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• 2000

The demands placed on portable wireless communication equipment include low cost, low supply voltage, low power, dissipation, low noise, high frequency of operation, and low distortion. These design requirements cannot be met satisfactorily in many cases without the use of RF inductors. However, implementing the inductor on-chip has been regarded as an impractical task because of excessive substrate capacitance and substantial resistive losses due to metallization and the conductive silicon substrate. Hence, there is a great incentive to design, optimize, and model spiral inductors on Si substrate. So, we analyzed a chip inductors using electromagnetic analysis and established a set of design rules for rectangular spiral inductors.

• Journal of electromagnetic engineering and science
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• v.8 no.1
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• pp.34-39
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• 2008

An RF front-end dual-conversion receiver for $3{\sim}5\;GHz$ MB-OFDM UWB systems is implemented in $0.18\;{\mu}m$ CMOS technology. The receiver includes a two-stage UWB LNA, an RF mixer, an IF I/Q mixer, and a frequency synthesizer. The proposed receiver adopts the dual-conversion architecture to mitigate the burden of design of the frequency synthesizer. Accordingly, the proposed frequency synthesizer generates four LO tones from only one VCO. The receiver front-end achieves power gain of 16.3 to 21 dB, NF of 7 to 7.6 dB over $3{\sim}5\;GHz$, and IIP3 of -21 dBm, while consuming 190 mW from a 1.8 V supply.