• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.12
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• pp.1043-1050
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• 2010

Fuel stratification and thermal stratification occur in the HCCI combustion chamber on a microscopic scale. They affect the ignition and combustion processes. In this study, the effect of the inhomogeneity in the mixture gas on the HCCI combustion process was investigated. Two-dimensional chemiluminescence images were captured using a framing camera to evaluate the flame structure. DME was used as the test fuel. First, the effect of inhomogeneity in the fuel distribution in the premixture was investigated for the four-stroke optically accessible engine. Then, by comparing the combustion of the homogeneous mixture in the rapid compression machine, which does not contain any residual gas, with the combustion in the four-stroke engine, the effect of inhomogeneity in temperature due to the residual gas was analyzed. The results showed that a time lag appears spatially in combustion under inhomogeneous conditions in the four-stroke engine. The spatial variation in the combustion without the residual gas in the rapid compression machine is less than that in the combustion in the four-stroke engine.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.1391-1393
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• 2002

There arc some problems on storage batteries which are called Secondary Battery, such as long charging time, limited cycle life, low coulomb efficiency and inaccurate residual power meter. To solve those problems, a complex system of capacitors and Super Capacitors of increased energy density. Though the capacitors alone arc not capable of delivering stable output, the accompanied circuits compensate the various characteristics all through the charge-and discharge-cycle. This paper deals with Energy Storage System with Super Capacitor for PV System Discussed in this paper are, explains the accompanied circuits of Super Capacitor which is compared with the Second Batteries.

• Journal of Mechanical Science and Technology
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• v.18 no.8
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• pp.1451-1460
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• 2004

A two-stroke Schnurle-type gasoline engine was modified to enable compression-ignition in both the port fuel injection and the in-cylinder direct injection. Using the engine, examinations of compression-ignition operation and engine performance tests were carried out. The amount of the residual gas and the in-cylinder mixture conditions were controlled by varying the valve angle rate of the exhaust valve (VAR) and the injection timing for direct injection conditions. It was found that the direct injection system is superior to the port injection system in terms of exhaust gas emissions and thermal efficiency, and that almost the same operational region of compression-ignition at medium speeds and loads was attained. Some interesting combustion characteristics, such as a shorter combustion period in higher engine speed conditions, and factors for the onset of compression-ignition were also examined.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.67.5-67
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• 2001

A closed loop system with a linear plant and nonlinearity in the feedback connection is analyzed for its quasi-static orbital stability by a state-space approach. First a periodic orbit is assumed to exist in the loop which is determined by describing function method for the given nonlinearity. This is possible by selecting a proper nonlinearity and a rigorous justification of the describing function method.[1-3, 18, 20]. Then by introducing residual operator, a linear perturbed model can be formulated. Using various transformations like a modified eigenstructure decomposition, periodic-averaging, charge of variables and coordinate transformation, the stability of the periodic orbit, as a solution of harmonic balance, can be shown by investigating a simple scalar function and result of linear algebra. This is ...

• Journal of the Korea Institute of Military Science and Technology
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• v.9 no.1 s.24
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• pp.13-23
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• 2006

A propellant mainly consisting of nitric ester including nitrocellulose and nitroglycerine is characteristic of being decomposed naturally. And this phenomenon is known as being affected mostly by its storing temperature and humidity. In this research, the effect of storing temperature and humidity on self life has been studied by measuring the contained quantity of residual stabilizer of propellant KM30Al, which are parts of 155MM propelling charge K676 and K677; the method for the measurement is acceleration aging test, and decomposition reaction equation, Eyring Equation and Berthlot Equation were used for the calculation. As result of this study, it was found that the storing temperature influenced seven times as large as the storing humidity upon the self life of the propellant KM30Al, Furthermore, especially in the high temperature region, the storing temperature had a dominant effect on the self life.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.11
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• pp.1047-1054
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• 2003

Smart battery pack (SBP) for notebook PCs was developed using a cylindrical-type lithium ion battery. Batteries were connected with three serial and two parallel, the nominal capacity and the maximum load of SBP was 4,000mAh and 4.0A, respectively. The SBP was composed of a protection IC, by which safety of lithium ion batteries is maintained against overcharge, overdischarge and overcurrent, and a smart IC, which calculates the remaining capacity and the remaining run time. In matching test on notebook PC using Battery Mark 4.0, real and smart data of END voltage coincided nearly and LB and LLB signal worked norma]]y. And there were errors of less than 1% between the real and the smart data on the residual capacity in the charge and discharge test.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.677-680
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• 2009

DC influence between pixel electrode and alignment layer (AL) in in-plane switching mode LCD was analyzed through DC equivalence-circuit equation induction, DC charge-discharge simulation, luminance and residual-DC measurement systems using test patterned (TP) cell. DC discharging rate (DDR) of single layer electrode was faster than that of double layer electrode and DDR of low resistance AL was faster than that of high resistance AL. DC discharging characteristics had a close relation to layer number and resistance between two electrodes.

• Journal of Information Display
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• v.6 no.4
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• pp.6-10
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• 2005

The dependence of hysteresis characteristics in low temperature poly-Si (LTPS) thin film transistors (TFTs) on the gate-source voltage (Vgs) or the drain-source voltage (Vds) bias is investigated and discussed. The hysteresis levels in both p-type and n-type LTPS TFTs are independent of Vds bias but increase as the sweep range of Vgs increases. It has been found that the hysteresis in both p-type and n-type LTPS TFTs originated from charge trapping and de-trapping in the channel region rather than at the source/drain edges.

• Korean Chemical Engineering Research
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• v.61 no.4
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• pp.635-644
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• 2023

Due to the rapid development of the livestock industry, particularly due to residual pharmaceutical antibiotics, environmental populations have been negatively affected. Herein, we report a ZnO/melamine-functionalized carboxylic-rich graphene oxide (ZFG) photocatalyst for visible light-driven photocatalytic degradation of tetracycline hydrochloride in aqueous solutions. The properties of the photocatalysts were evaluated by XRD, FTIR, XPS, Fe-SEM, HR-TEM, TGA, Raman spectroscopy, UV-Vis spectroscopy, zeta potential, and electrochemical measurements. The photocatalytic activity was measured using high-performance liquid chromatography. The photocatalytic properties of the ZFG photocatalyst evaluated against the tetracycline hydrochloride (TCH) antibiotic under visible light irradiation showed superior photodegradation of 96.27% within 60 min at an initial pH of 11. The enhancement of photocatalytic degradation was due to the introduction of functionalized graphene, which increases the light-harvesting capability and molecular adsorption capability in addition to minimizing the recombination rate of photogenerated charge carriers due to its role as an electron acceptor and mediator.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.4
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• pp.149-156
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• 2006

This paper investigates the steady state combustion characteristics of LPG homogeneous charge compression ignition(HCCI) engine with variable valve timing(VVT) and dimethyl ether(DME) direct injection, to find out the benefits in exhaust gas emissions. VVT is one of the attractive ways to control HCCI engine. Hot internal residual gas which is controlled by VVT device, makes fuel is evaporated easily, and ignition timing is advanced. Regular gasoline and liquefied petroleum gas(LPG) were used as main fuel and dimethyl ether(DME) was used as ignition promoter in this research. Operating range and exhaust emissions were compared LPG HCCI engine with gasoline HCCI engine. Operating range of LPG HCCI engine was wider than that of gasoline HCCI engine. The start of combustion was affected by the intake valve open(IVO) timing and the ${\lambda}TOTAL$ due to the latent heat of vaporization, not like gasoline HCCI engine. At rich operation conditions, the burn duration of the LPG HCCI engine was longer than that of the gasoline HCCI engine. CAD at 20% and 90% of the mass fraction burned were also more retarded than that of the gasoline HCCI engine. And carbon dioxide(CO2) emission of LPG HCCI engine was lower than that of gasoline HCCI engine. However, carbon oxide(CO) and hydro carbon(HC) emission of LPG HCCI engine were higher than that of gasoline HCCI engine.