• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.5
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• pp.51-66
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• 1997

A heat transfer model of the intake valve in a spark ignition engine is presented, which is calibrated with a number of the valve temperature profiles measured during engine warm-up for the gaseous fuel(propane). The valve is divided into four identical elements for which the assumption of lumped thermal mass is applied. The calibration is made so that the difference between the measued and simulated valve temperatures becomes minimal. Then the model is applied to the cases of the liquid fuel(indolene) to estimate the amount of the liquid fuel vaporized from the intake valve by assuming that fuel evaporation accounts for the deficit of the heat balance budget. The results of the model show quantitative contribution of each heat transfer source to the heat balance. The behavior of the calculated mass fraction of the fuel vaporized from the intake valve explains how the liquid fuel evaporate during engine warm-up. The mass fraction at warmed-up condition is closely related with the fraction directly targeted on the valve back by the fuel spray geometry.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1996.10a
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• pp.34-39
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• 1996

In many industrial applicatiosns such as machine tools and automation equipments the control performance of the feed-drive systems as positioning devices of the tools and workpieces have great influences on the quality of related machines. For many electrically driven mechanical feed systems resilient couplings between motors and mechanical elements which mostly consist of elasttic shafts and gears often are unavoidable. Commonly these systems can be regarded as an elastic multi-mass systems can be regarded as an elastic multi-mass system which is dealt with this contribution. S high performance speed or position control can only be achieved with the considering of the mechanical elastic characteristics of the system. n this paper some practic characteristics of the system In this paper some practical information is given about experience in modeling design simulation and experiments for linear elastic multi-mass system,

• Journal of Korean Society for Atmospheric Environment
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• v.16 no.6
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• pp.565-572
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• 2000

To quantitatively estimate mass contribution of long-range transported yellow sand, their sources should be separated independently from various local soil sources having similar elemental compositions. While it is difficult to estimate total mass loadings of pure yellow sand by traditional bulk analysis, it can be clearly solved by an particle-by-particle analysis. To perform this study, two yellow sand samples and three local soil samples were collected by a mini-volume sampler. These samples were three analyzed using a scanning electron microscope(SEM) equipped with an energy dispersive x-ray analyser (EDX) was used to obtain basic chemical information of individual yellow san particles. A total of 19 elements in a single particle were measured to develop a source profile with newly created homogeneous particle classes (HPCs) as chemical variables. The present study showed that the yellow sand samples as well as three local soil samples were characterized with reasonably well created HPCs. Finally the mass fraction of each HPC in each sample was calculated and then compared each other.

• Proceedings of the Korean Nuclear Society Conference
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• 1998.05a
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• pp.553-558
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• 1998

The calibrating method for an electrochemical Probe, neglecting the effect of the normal velocity on the mass transport, can cause large errors when applied to the measurement of wall shear rates in thin wavy flow with large amplitude waves. An extended calibrating method is developed to consider the contributions of the normal velocity. The inclusion of the turbulence-induced normal velocity term is found to have a negligible effect on the mass transfer coefficient. The contribution wave-induced normal velocity can be classified on the dimensionless parameter V. If V above a critical value of V, $V_{crit}$, the effects of the wave-induced normal velocity become larger with an increase in V. IF V its effects negligible for V < $V_{crit}$. The unknown shear rate is numerically determined by solving the 2-D mass transport equation inversely. The president inverse method can predict the unknown shear rate more accurately in thin wavy flow with large amplitude waves than the previous method.

• Journal of Korean Institute of Industrial Engineers
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• v.22 no.3
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• pp.413-426
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• 1996

Modern society, as a result of high industrial technology, is characterized by a series of mass production, moss consumption and mass disposal. As the mass disposal is known as the major culprit of destroying ecological system of our environment, human prosperity is in turn threatened by this indiscrete activities. Under current industrial technology which pursuit maximum profit, environmental problems could not be solved. This paper proposes recycle manufacturing systems of assemble products as a measure of current non-recycle manufacturing systems. Products are also composed of a number of ports. All parts are represented by a function of time cost performance variable as reuse level. We develop on information systems which give all the information on reused and recycled parts. We try to implement this result on a real fields. We confide ourselves to the contribution to on effective solution of environmental problems and to give profit to assembly manufacturing and consumers.

• Journal of Industrial Technology
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• v.31 no.A
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• pp.33-38
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• 2011

In an express tilting train, side wall insulating the noise from the exterior sound source consists of two parts. One is the layered composite panel including aluminum honeycomb, glass wool and nomex honeycomb. The other is the double glazed window. In this study, sound insulation performance of the two parts is investigated by mass law and experiment. Based on ASTM E2249-02, the intensity sound transmission loss (TL) is measured on the specimens of the two parts. Mass law deviation (MLD) is considered in order to compare the sound insulation performance in respect of weight. Contribution of each part to the sound insulation is analyzed and the sound insulation strategy for the interior noise reduction is investigated.

• Journal of the korean Society of Automotive Engineers
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• v.9 no.1
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• pp.40-48
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• 1987

A Mini-Dilution Tunnel is described as a scaled down comparision of a Standard Tunnel. The paper presents the result of experimental investigations on measuring the particulate emission of a diesel engine in a Mini and a Standard Dilution Tunnel. The result offers a contribution to understanding about the influence of several parameters including dilution ratios, mixture temperatures, mixture conditions, filter temperatures, and flow conditions. In the experiment either increasing the filter temperature and mixture temperature at a fixed dilution ratio or increasing the dilution ratio at a fixed filter temperature and mixture temperature resulted in a decrease in the total particulate mass. These changes in total particulate mass were attributed to the changes in the soluble organic fraction of the particulate sample. Also, mass differences between the Mini and the Standard Dilution Tunnel for the same engine conditions were within approximately 15% of each other.

• Journal of Astronomy and Space Sciences
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• v.39 no.3
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• pp.99-108
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• 2022

There are two models that explain the rotation curves of galaxies: dark matter, which gives the missing contribution to the gravitational potential of the standard theory of gravity, and modified theories of gravity, according to which the gravitational potential is created by ordinary visible mass. Both models have some disadvantages. The article offers a new look at the problem of galactic rotation curves. The author suggests that the moment of inertia creates an additional gravitational potential along with the mass. The numerical simulation carried out on the example of fourteen galaxies confirms the validity of such an assumption. This approach makes it possible to explain the constancy of gas velocities outside the galactic disk without involving the hypothesis of the existence of dark matter. At the same time, the proposed approach lacks the disadvantages of modified theories of gravity, where the gravitational potential is created only by the mass of visible matter.

• Journal of Korean Society for Atmospheric Environment
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• v.28 no.4
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• pp.411-422
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• 2012

Ground-based in-situ measurements of aerosol optical properties at Gosan climate observatory have been analyzed to investigate the optical contribution of Asian dust and polluted particles on light absorption in springtime 2011. During the Asian dust episode, the contribution of Asian dust particle to aerosol absorption coefficient estimated about 45% at 370 nm and about 23% at 520 nm. Especially, black carbon in dust plume contributes about 48% to aerosol light absorption at 520 nm since the airmass are transported from the Gobi and inner Mongolia deserts, and this airmass comes across the northeastern coast of China, near the Shandong Peninsula. In pollution case, the contributions of dust particle and black carbon to aerosol absorption coefficient estimated about 41% and 11% at 370 nm, respectively. However, pollution case shows the highest light absorption of 48% for brown carbon at 370 nm, which indicates the significantly high mass concentration of organic carbon ($6.3{\pm}2.2{\mu}g\;m^{-3}$) in pollution plume can contribute to the increase of light absorption at near-UV spectral region.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.09a
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• pp.450-452
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• 2004

Using factor analysis and bivariate comparisons of major components in ground water, three geochemical processes were identified as controlling factors of ground water chemistry; 1) natural mineralization by water rock interactions, 2) effect of seawater which includes salinization by seawater near seashores and deposition of sea salt, and 3) nitrate contamination by N fertilization. Contribution of rainfall was also estimated from the measured composition of wet deposition. The geochemical processes were separated using total alkalinity as an indicator for natural mineralization, Cl for effect of seawater, and nitrate for N fertilization. Relatively high correlation of major components with nitrate suggests that nitrification of nitrogenous fertilizers significantly affects ground water chemistry. Total cations derived from nitrate sources have good linearity for nitrate in equivalent basis with a slope of 1.8, which is a mean of proton production coefficients in nitrification of two major compounds in nitrogenous fertilizers, ammonium and urea. Contribution of nitrate sources to base cations, Cl, and SO$_4$ in ground water was determined considering maximum contribution of natural mineralization to estimate a threshold of the effect of N fertilization for ground water chemistry, which shows W fertilization has a greatest effect than any other processes in ground water with nitrate concentration greater than 50 mg/L for Ca, Mg, Na and with concentration greater than 30 mg/L for Cl and SO$_4$.