• Journal of the Korean Institute of Telematics and Electronics S
• /
• v.34S no.6
• /
• pp.94-103
• /
• 1997

This paper presents motor speed and revolution angle detection method using a sinusoidal AC tacho-generator. The 2-phase or 3-phase output tacho-generator can be adopted, and its' output voltages must have sinusoidal waveforms. Because the detection algorithm is simple, the proosed method can be implemented with analog devices or microprocessor conveniently. And the proposed method has a very short detection delay time. Especially in the analog implementation, there is no delay time without the settling time of analog devices. With the experimental results, it is verified that the proposed method can acculately detect the instantaneous motor speed and revolution angle over the wide ranges.

• Journal of Power System Engineering
• /
• v.18 no.1
• /
• pp.22-31
• /
• 2014

This paper introduced the new calibration algorithm of a straight-type five-hole pressure probe necessary for calculating three-dimensional flow velocity components. The new velocity data reduction method using both a commercial two-dimensional curve-fitting program and the zone partition method of a calibration map was firstly introduced in this study. This new calibration method can be applied up to the wide flow angle of ${\pm}80^{\circ}$ despite of using a five-hole pressure probe because this data reduction method showed a comparatively good performance in calculating yaw and pitch angles from the calibration map.

• Tribology and Lubricants
• /
• v.10 no.4
• /
• pp.33-42
• /
• 1994

An influence of inlet pressure on the performance of sector-shaped pad thrust bearings is investigated theoretically. The optimum conditions of film thickness or the optimum positions of pivot are found through the evaluation of load capacity for all available conditions of film thickness, under the operating conditions which the thermal and pad deformation effects can be neglected. The bearing performance including the inlet pressure effects is obtained for a wide operating ranges that inertia parameter(Re$^{*}$) is up to unity, and for the various cases of pad extent angle (number of pad) and the three cases of the angle between pads. The results show that the inlet pressure has a large influence on the performance of sector-shaped pad thrust bearings. In the design of sector-shaped pad bearings, due to the inlet pressure, the optimum number of pad is varied with the operating speed and the angle between pads, and the optimum position of pivot is located toward the leading edge along with the operating speed increases.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2000.01a
• /
• pp.43-44
• /
• 2000

The fringe-field switching (FFS) display is known to exhibit wide-viewing-angle and high transmittance. We have simulated pretilt effects on electro-optic characteristic of the device when a liquid crystal with positive and negative dielectric anisotropy is used. The results show that asymmetry in contour of luminance and light leakage in the dark state are increased but voltage-dependent transmittance curves remain about the same, as the pretilt angle increases to $10^{\circ}$.

• Journal of ILASS-Korea
• /
• v.7 no.2
• /
• pp.16-21
• /
• 2002

Liquefied petroleum gas (LPG) has been used as motor fuel due to its low emissions and low cost. This study addresses the analysis of the LPG spray behavior near injection nozzle. The LPG spray photographs are compared with sprays of diesel fuel at the same conditions. The LPG spray photos show that the dispersion characteristic depends very sensuously on the ambient pressure soon after injection. The spray angle is very wide in a low ambient pressure condition until the saturated pressure at this test condition, but the angle value is quickly reduced at the condition over the pressure.

• Proceedings of the KIEE Conference
• /
• 2005.04a
• /
• pp.232-234
• /
• 2005

In this paper, A fuzzy logic based turn-off angle compensator for torque ripple reduction in a linear switched reluctance motor is proposed. The turn-off angle, as a complex function of motor speed and current, is automatically changed for a wide speed range to reduce torque ripple. Simulation results are presented that show ripple reduction when the turn-off angle compensator is used.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2005.05a
• /
• pp.54-57
• /
• 2005

We have designed a single gap transflective liquid crystal display (LCD) driven by a fringe electric field, in which the +LC (${\Delta}{\varepsilon}$=7.4, rubbing angle= $80^{\circ}$) is homogeneously aligned in the initial state. This device is a problem that the voltage-dependent transmittance and reflectance curves do not match each other. Thus a dual driving circuit is required. This study shows that optimization of the rubbing angle in the transmissive and reflective regions solves this problem so that the transflective display with a single cell gap and single gamma curve for reflective and transmissive region is possible.

• Journal of Advanced Marine Engineering and Technology
• /
• v.18 no.4
• /
• pp.43-52
• /
• 1994

I investigated experomentally the spray characteristics to the operating conditions and the shapes of internal mixing twin fluid atomizer. The wide variations of air per liquid ratio are conducted to predit the influences of the Sauter mean diameter(SMD), spray angle, distribution of drop size, the flowing condition of gas and length, flowing, area of gas and liquid, and diameter, number and place of the orifice. In this experiment, air per liquid raio, mixing chamber length per diameter, orifice diameter, and the flowing area ratio of gas and fluid influences greatly on SMD, spray angle, distribution of drop size and intermittent fluctuation region.

• International conference on construction engineering and project management
• /
• 2009.05a
• /
• pp.60-70
• /
• 2009

This paper explores the ways in which collaborative working among multiple disciplines in building projects can be more effective and efficient. It focuses on the support that can be provided by the latest development in information and communication technologies. It also considers the growing interdependence between participants in the process and their changing roles as they harness the power of the new technologies in new collaborative arrangements. It is argued that collaborative working should be addressed holistically from the technological angle, the social angle, as well as the organisational angle, to ensure its successful implementation in the construction industry. A case study is given to illustrate the use of ICT in supporting value management studies. The key issues surrounding the emerging field of research - collaborative construction information management - and the potential benefits and challenges of its wide adoption are discussed at depth.

• Macromolecular Research
• /
• v.16 no.7
• /
• pp.575-585
• /
• 2008

There are two beamlines (BLs), 4C1 and 4C2, at the Pohang Accelerator Laboratory that are dedicated to small angle X-ray scattering (SAXS). The 4C1 BL was constructed in early 2000 and is open to public users, including both domestic and foreign researchers. In 2003, construction of the second SAXS BL, 4C2, was complete and commissioning and user support were started. The 4C2 BL uses the same bending magnet as its light source as the 4C1 BL. The 4C1 BL uses a synthetic double multilayer monochromator, whereas the 4C2 BL uses a Si(111) double crystal monochromator for both small angle and wide angle X-ray scattering. In the 4C2 BL, the collimating mirror is positioned behind the monochromator in order to enhance the beam flux and energy resolution. A toroidal focusing mirror is positioned in front of the monochromator to increase the beam flux and eliminate higher harmonics. The 4C2 BL also contains a digital cooled charge coupled detector, which has a wide dynamic range and good sensitivity to weak scattering, thereby making it suitable for a range of SAXS and wide angle X-ray scattering experiments. The general performance of the 4C2 BL was initially tested using standard samples and further confirmed by the experience of users during three years of operation. In addition, several grazing incidence X-ray scattering measurements were carried out at the 4C2 BL.