• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.3
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• pp.167-176
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• 2003

This study is focused on the development of a new muffler. A control valve installed in the exhaust system is operated by torsion springs, and its open angle is controlled automatically corresponding to the engine operating conditions. A control valve and a control muffler sensing exhaust-gas pressure are made f3r developing a new muffler. The experiments were done using an exhaust system simulator having the same pulsation wave frequency and similar pulsation propagation characteristics of a real exhaust system. The purpose of this study is to develope a new muffler system which has improved noise reduction quality and less power loss than conventional mufflers and electronic-control mufflers. Finally the characteristic of noise compared with conventional muffler and muffler sensing exhuast-gas pressure.

• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.565-568
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• 2006

This paper achieved dynamic characteristics with test to use solenoid valve for flight model that have present. Designed pressure control virtual system which PWM solenoid valve to use test result. Examination compared solenoid valve dynamic characteristics in atmosphere and cryogenic fluid and presented technique and valuation method that measured upstream and down stream pressure of solenoid valve, as well as, temperature, excitation voltage etc. These test results could confirm solenoid valve response time and maximum using frequency characteristic at use in atmosphere and cryogenic temperature and this derived design variables pressure control system from those bases.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.25 no.11
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• pp.612-616
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• 2013

A circular CAV damper has been developed, based on the investigation of the pressure loss, and the flow-resisting moment by the damper blade. When a torsional spring is attached to the damper axle, and the setting angle is adjusted to around $82^{\circ}$, the volume rate across the damper is almost independent of the static pressure. Such a CAV characteristic appears at an opening angle between $40^{\circ}$ and $60^{\circ}$, where the normalized moment decreases linearly with the angle. In addition, by adjusting the setting angle, the volume rate can be controlled to within 10% error, regardless of the pressure loss.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.32 no.11
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• pp.930-936
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• 2008

This paper studies the effect of pad at initial stage and wear during braking on the dynamic contact pressure distribution. Wear is influenced by variable factor (contact pressure, sliding speed, radius, temperature) during dynamic braking and variation in contact pressure distribution. Many researchers have conducted complex eigenvalue analysis considering wear characteristic with Lim and Ashby wear map. The conventional analysis method is assumed the pad has smooth and flat surfaces. The purpose of this paper is to validate that wear rate induced by braking is considered for the precise squeal prediction. After obtaining pad wear from experiment, it is incorporated with FE model of brake system. Finally, the comparisons in fugitive nature of squeal will be carried out between the complex eigenvalue analysis and noise dynamometer experiment.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.1 s.106
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• pp.89-100
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• 2006

This paper presents an analytical approach to describe the variation in the vibration characteristics such as the natural frequency of a piezoelectric transducer under static pre-pressure. The transducer considered in this paper is a bolt-clamped Langevin-type transducer, which consists of a couple of piezoelectric discs, a couple of metal blocks for added mass effect, and a bolt to tighten them. A new analysis model for the transducer has been developed by taking into account the contact area between the piezoelectric ceramic disc and the metal block. The variation of the resonance frequency due to the pre-pressure has been calculated and compared with measured results reported earlier.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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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

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2005.10a
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• pp.361-366
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• 2005

Since most soils exist above the ground water table, negative pore pressure exist in unsaturated soils. Negative pore water pressure in unsaturated soil affects the soil structure and degree of saturation and it is important for accurate evaluation of unsaturate flow and behavior. This negative pore pressure is called a matric suction which causes an increased shear strength. Therefore, it is required that the effect of increase in the shear strength should be included in a geotechnical analysis. From the test result, the influence of net confining pressure and matric suction on the shear strength was analyzed and strength parameter was increased with matric suction increase and a unliner relationship was found to relate matric suction and shear strength.

• Journal of ILASS-Korea
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• v.7 no.2
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• pp.16-21
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• 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 Korea Concrete Institute Conference
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• 2005.05a
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• pp.507-510
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• 2005

Euro form which constructs the present RC structures is used widely by the form method of construction of a wall type structure had much consumption of the human power and equipments by the assembly and the demolition, and the complement was required according to demerit with much leakage of cement paste by the form joint, so it developed the new pillar type form system. On the study, in order to consider the modification characteristic by lateral pressure which does the influence most important for the new developed pillar type form system performance, research of a paper manufactured a miniature wall form model, and advanced performance evaluation focusing on lateral pressure. Moreover, lateral pressure evaluation of a new style system was actually gone on through the on-site experiment about a part of wall type srutcture spot for a model experiment and its result on the foundation which is the purpose in evaluating on-site application possibility propriety at the foundation time of wall type concrete structure construction of a pillar type form system.

• 전기의세계
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• v.27 no.3
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• pp.36-42
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• 1978

It has been investigates that electric characteristics of plasma electron beam in N$_{2}$, H$_{2}$ and Ar gas jars under various gas pressures during electron beams are formed. The results are as follows: 1)Electron beam is formed in the region of positive resistance on the characteristic curve. This phenomenon is identical in N$_{2}$, H$_{2}$ and Ar gases. 2)But in Ar gas, electron beam is formed at relatively lower gas pressure than in H$_{2}$ and N$_{2}$. 3)In pure gas either N$_{2}$, H$_{2}$ and N$_{2}$ the lower the gas pressure, the higher the voltage drop for the same electron beam current. 4)The region in which electron beam is formed is limited at a given pressure. 5)Beyond the limit mentioned above, it becomes glow discharge state and the current increases radically. 6)At a given gas pressure, electron beam voltage, that is, electrical power input increases with gap length.