• Journal of the Mineralogical Society of Korea
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• v.27 no.4
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• pp.283-291
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• 2014

Talc ($Mg_3Si_4O_{10}(OH)_2$), one of sheet silicates, is soft and has been widely used in industry. Powdered talc specimen was synthesized at the pressure of 200 MPa and temperature of $600^{\circ}C$ using external heated hydrothermal high pressure apparatus. High pressure angular dispersive X-ray diffraction (ADXRD) mode experiments were performed at the Pohang Light Source (PLS) using the symmetrical diamond anvil cell (SDAC). Compression pressure was loaded up to 11.06 GPa at room temperature. This synthetic talc shows no phase transition(s) within the present pressure limit. Based on ADXRD data, bulk modulus of talc was calculated to be 72.4 GPa using Birch-Muranghan equation of state (EOS). This value is lower than that of natural talc determined previously.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.1
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• pp.114-122
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• 1999

Reignition as special cases of acoustic pressure responses of flame are numerically studied by employing methanol droplet flame as a laminar flamelet. Quasi-steady flame responses occur in the range of small amplitude, low frequency oscillation. Reignition phenomena can occur when, by increasing the frequency of large amplitude acoustic pressure, the magnitude of characteristic acoustic time is the same order of that of characteristic reaction time of flames. And more increasing of amplitude of acoustic pressure induces the direct extinction of flame. Flame can sustain its own intensity even under the steady extinction temperature in case of high frequency acoustic oscillation, and this tendency is remarkable with increasing frequency. Reignition regime with respect to amplitude and frequency of acoustic pressure doesn't exist in low frequency($10^2$ Hz, in this study), but broadens with frequency of acoustic pressure.

• Tribology and Lubricants
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• v.24 no.2
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• pp.55-62
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• 2008

In recently designed diesel engines, the running conditions for piston pin bearings have become very severe due to combustion pressure and temperature increase. In this paper, it will be investigated the tendency of piston pin rotating motion by calculating the friction coefficient at piston pin bearings, the oil film thickness and the frictional torques induced by hydrodynamic shear stress. Finally, the pressure distributions on the oil film of piston pin bearings will be found by two-dimensional lubrication analysis in order to help the optimum design of the bearings of piston pin. Specially, it is investigated how the changes in combustion pressure at exhaust and intake stroke and the pressure-viscosity index effect on the film pressure distribution.

• Transactions of the Korean Society of Mechanical Engineers
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• v.2 no.2
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• pp.42-46
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• 1978

Thermal conductivities of Freon-12 and Freon-22 were measured at room temperature up to 35 MPa with the aid of transient hot wire method. Glycerin was used to check the performance of the experimental equipment. The thermal conductivities of Freon-12 and Freon-22 at the maximum pressure, 35 MPa, were increased by 25% approximately for those at satufated state.

• 제어로봇시스템학회:학술대회논문집
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• 1990.10a
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• pp.85-89
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• 1990

In this paper, the design of boiler drum level control system is important in power plant is studied. First of all, pressure compansation of level for boiler drum which is close tank with high temperature and pressure is designed. Physical penomena of drum level are analysed, controllers are designed, and simulation results are shown. Designed controller have a good performance compare with PI controller. Predictive controller of boiler drum level control system is proposed. It will be good system for boiler drum level control to reject the disturbance according to lead increase or decrease.

• Proceedings of the PSK Conference
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• 2002.10a
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• pp.425.2-425.2
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• 2002

The purpose of this study was to prepare thermo-sensitive solid-lipid nanoparticles (SLNs) with a lipid melted at human body temperature and to evaluate physicochemical properties of SLNs containing retinol. anti-wrinkle agent. as a model drug. SLNs were prepared using a high pressure homogenizing method. The SLNs were composed of retinol as a model drug. thermo-sensitive lipid (DS-CBS) as a lipid core. and egg phosphatidylcholine and Tween 80 as surfactants. Manufacturing variables such as homogenization pressure. (omitted)

• Journal of Electrical Engineering and information Science
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• v.1 no.1
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• pp.45-50
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• 1996

This paper mainly describes the wind load assumption of 765kV transmission towers. We analyzed wind velocity data a meteorological observatories to get the wind velocity of 50 years return period by using Gumbel I type extreme value distribution. By multi-correlative regression analysis method, wind velocity at no observation site was obtained. Reference dynamics wind pressure map was obtained from above analysis and the wind pressure was classified as three regio in high temperature season.

• Journal of the Korean Society of Combustion
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• v.12 no.4
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• pp.1-7
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• 2007

Carbon monoxide (CO) is not only an important intermediate species in chemical reaction mechanisms of hydrocarbon fuel combustion, but also a crucial pollutant species emitted from automotive engines. To better understand the physical processes impacting CO emissions, the development of laser-based measurement techniques that can visualize in-cylinder CO distributions is desirable. Among these techniques, Laser-Induced Fluorescence (LIF) is a sensitive and species-selective detection technique capable of good spatial resolution. However, some technical matters such as deep UV excitation, severe pressure dependency of the LIF signal, and potential interference from other species have been major challenges for CO LIF application. This study is focused on investigating the feasibility of CO two-photon LIF in a direct-injection diesel engine operating at typical pressure and temperature conditions with commercial grade diesel fuel. Spectroscopic analysis shows that the CO fluorescence signal can be separated from $C_2$ Swan band or broadband fluorescence from PAHs when the signal is collected near 483 nm. The signal-to-noise ratio of CO LIF deteriorate rapidly as pressure is increased, following $P^{-1.49}$ which matches the theoretical signal pressure dependency.

• Journal of Power System Engineering
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• v.17 no.4
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• pp.45-50
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• 2013

This paper presents the comparison of heat transfer and pressure drop of various secondary refrigerants (single-phase and two-phase) in the indirect refrigeration system. The main results were summarized as follows: In case of heat transfer, it is useful to use secondary refrigerants in low evaporating temperature region and the heat transfer coefficient of single-phase is larger than two-phase secondary refrigerants. In case of pressure drop, it is useful to use secondary refrigerants in high evaporating temperature region and the pressure drop of two-phase is smaller than single-phase secondary refrigerant. Also, $CO_2$ is the best useful because pressure drop of $CO_2$ among the secondary refrigerants is the smallest.

• Journal of Mechanical Science and Technology
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• v.17 no.11
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• pp.1746-1755
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• 2003

Operating characteristics of a triple pressure reheat HRSG are analyzed using a commercial software package (Gate Cycle by GE Enter Software). The calculation routine determines all the design parameters including configuration and area of each heat exchanger. The off-design calculation part has the capability of simulating the effect of any operating parameters such as power load, process requirements, and operating mode, etc., on the transient performance of the plant. The arrangement of high-temperature and intermediate-temperature components of the HRSG is changed, and its effect on the steam turbine performance and HRSG characteristics is examined. It is shown that there could be a significant difference in HRSG sizes even though thermal performance is not in great deviation. From the viewpoint of both economics and steam turbine performance, it should be carefully reviewed whether the optimum design point could exist. Off-design performance could be one of the main factors in arranging components of the HRSG because power plants operate at various off-design conditions such as ambient temperature and gas turbine load, etc. It is shown that different heat exchanger configurations lead to different performances with ambient temperature, even though they have almost the same performances at design points.