• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.1011-1014
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• 2006

Turbo blower generates high peaks when it operates at high pressure region. The fan of the air-cleaner system, operates especially high pressure region due to several filters, generates high noise level. In this case, the tonal sound of BPF makes people annoyance. The blower of air-cleaner has several high resistance filters in its inlet area and rotates above 900rpm Moreover, for the compact design, the size of the blower should be reduced 10%. The reduced diameter of blower makes low flow rate and high noise level. In order to reduce the noise, new blade shape was suggested and optimized

• 한국반도체및디스플레이장비학회:학술대회논문집
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• 한국반도체및디스플레이장비학회 2002년도 추계학술대회 발표 논문집
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• pp.59-63
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• 2002

This paper reports on the fabrication process and characteristics of a ceramic thin-film pressure sensor based on Ta-N strain-gauges for harsh environment applications. The Ta-N thin-film strain-gauges are sputter-deposited on a thermally oxidized micromachined Si diaphragms with buried cavities for overpressure tolerance. The proposed device takes advantage of the good mechanical properties of single-crystalline Si as a diaphragm fabricated by SDB and electrochemical etch-stop technology, and in order to extend the temperature range, it has relatively higher resistance, stability and gauge factor of Ta-N thin-films more than other gauges. The fabricated pressure sensor presents a low temperature coefficient of resistance, high-sensitivity, low non-linearity and excellent temperature stability. The sensitivity is 1.21 ~ 1.097 mV/V.kgf/$\textrm{cm}^2$ in temperature ranges of 25~ $200^{\circ}C$ and a maximum non-linearity is 0.43 %FS.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2000년도 추계학술대회 논문집
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• pp.499-505
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• 2000

The shape of the KHST, and of the power car in particular, is largely determined by aerodynamic considerations. At high speeds, air resistance accounts for the major part of overall resistance to forward motion. Further points to be considered are environmentally undesirable acoustic phenomena and pressure waves. Minimizing power requirements and environmentally-unfriendly noise and pressure waves are thus major objectives in the development of the KHST. When deciding on the aerodynamic design of the power car, the entire train set has to be taken into consideration. This paper describes the design process and results about the front shape of the KHST.

• 한국철도학회:학술대회논문집
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• 한국철도학회 1999년도 추계학술대회 논문집
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• pp.115-120
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• 1999

The shape of the KHST, and of the power car in particular. is largely determined by aerodynamic considerations. At high speeds, air resistance accounts for the major part of overall resistance to forward motion. Further points to be considered are environmentally undesirable acoustic phenomena and pressure waves. Minimizing power requirements and environmentally-unfriendly noise and pressure waves are thus major objectives in the development of the KHST. When deciding on the aerodynamic design of the power car, the entire train set has to be taken into consideration. This paper describes the design process and results about the front shape of the KHST.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.737-740
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• 2001

This paper describes the fabrication and characteristics of CrN thin-film type pessure sensors, which the sensing elements were deposited on SUS. 630 diaphragm by DC reactive magnetron sputtering in an argon-nitride atmosphere(Ar-(10%)N$_2$). The optimized condition of CrN thin-film sensing elements was thickness range of 3500${\AA}$ and annealing condition(300$^{\circ}C$, 3 hr) in Ar-10 %N$_2$deposition atmosphere. Under optimum conditions, the CrN thin-films for strain gauges is obtained a high resistivity, $\rho$=1147.65 ${\mu}$$\Omega$cm, a low temperature coefficient of resistance, TCR=-186 ppm/$^{\circ}C$ and a high temporal stability with a good longitudinal, 11.17. The output sensitivity of fabricated CrN thin-film type pressure sensors is 2.36 mV/V, 4∼20 mA and the maximum non-linearity is 0.4 %FS and hysteresis is less than 0.2 %FS.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집 Vol.3 No.2
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• pp.731-734
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• 2002

This paper describes on the fabrication and characteristics of a ceramic thin-film pressure sensor based on Ta-N strain gauges for harsh environment applications. The Ta-N thin-film strain gauges are sputter deposited onto a micromachined Si diaphragms with buried cavity for overpressure protectors. The proposed device takes advantages of the good mechanical properties of single crystalline Si as diaphragms fabricated by SDB and electrochemical etch-stop technology, and in order to extend the operating temperature range, it incorporates relatively the high resistance, stability and gauge factor of Ta-N thin-films. The fabricated pressure sensor presents a low temperature coefficient of resistance, high sensitivity, low non-linearity and excellent temperature stability. The sensitivity is $1.097{\sim}1.21mV/V{\cdot}kgf/cm^2$ in the temperature range of $25{\sim}200^{\circ}C$ and the maximum non-linearity is 0.43 %FS.

• Journal of Welding and Joining
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• 제31권5호
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• pp.59-63
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• 2013

A bendable electronic module has been developed for a mobile application by using a low-cost roll-to-roll manufacturing process. In flexible embedded electronic module, a thin silicon chip was embedded in a polymer-based encapsulating adhesive between flexible copper clad polyimide layers. To confirm reliability and durability of prototype bendable module, the following tests were conducted: Moisture sensitivity level, thermal shock test, high temperature & high humidity storage test, and pressure cooker tester. Those experiments to induce failure of the module due to temperature variations and moisture are the experiment to verify the reliability. Failure criterion was 20% increase in bump resistance from the initial value. The mechanism of the increase of the bump resistance was analyzed by using non-destructive X-ray analysis and scanning acoustic microscopy. During the pressure cooker test (PCT), delamination occurred at the various interfaces of the bendable embedded modules. To investigate the failure mechanism, moisture diffusion analysis was conducted to the pressure cooker's test. The hygroscopic characteristics of the encapsulating polymeric materials were experimentally determined. Analysis results have shown moisture saturation process of flexible module under high temperature/high humidity and high atmosphere conditions. Based on these results, stress factor and failure mechanism/mode of bendable embedded electronic module were obtained.

• 한국강구조학회 논문집
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• 제8권3호통권28호
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• pp.47-54
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• 1996

Recently Sucessive progress in train technic has enabled us to constructed high-speed railways for ourselves. This caused more rapid train more pressure on a track and speedier track break-down. Especially in the construction of high-speed rails for high-speed traveling and safety accurate breaking distance is essential and not only computation of rolling resistance in theory but also verification through real measurement are important in basic material for breaking and starting load caused during the train running. In this study, we measured traveling resistance and calculated traveling resistance formula in the case of the SAEMA-EUL which consists of main part of current passenger trains and frights in this country.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2000년도 유체기계 연구개발 발표회 논문집
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• pp.259-264
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• 2000

The functions of the plug valve are the control of flow rate as well closing and opening pipe lines. Analyses on the flow characteristics in plug valve port are required to improve the performance and safety at severe operating conditions such as high-pressure and high-temperature. In this study, numerical analyses are carried out with varying the opening rate (fraction of the full open to close) of the valve and the shapes of valve Uk: straight, convex, concave and mixed shapes. The parameters influencing the flow characteristics in the valve are the discharge coefficient( $C_v$) and the resistance coefficient( K). Therefore, the distributions of static pressure, velocity vector and stream lines are investigated, and $C_v$ and K are calculated in each opening rate and shape. In case of full open, the static pressure passed through the valve port has almost been recovered. However, in case of other opening rates, the pressure does not permanently regained due to pressure drop leading to loss. This phenomenon in each shape of the valve shows the different behaviors. Calculation results show that the mixed shape has the best flow attribute.

• 한국기계가공학회지
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• 제18권8호
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• pp.82-90
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• 2019

We propose an equivalent model of a sintered metal mesh filter calculated by Ergun's equation and polynomial regression for the CFD analysis of breakaway devices at a hydrogen fueling station. CFD analysis of filters that cause high pressure loss is essential because breakaway devices in high-pressure hydrogen conditions require low pressure loss. A differential pressure experiment with a filter was performed in a low-pressure air condition considering similarities. An equivalent model was developed by deriving the resistance value by the polynomial regression using the experimental results. The results of CFD analysis using the equivalent model show that there was almost no error in the operating condition of the breakaway device compared to the experimental results. Through this work, we believe that the proposed equivalent model of a filter can be applied to the analysis of breakaway devices in hydrogen fueling stations. We will study how to optimize the shape and position of the filter in breakaway devices using the developed equivalent model.