• Transactions on Electrical and Electronic Materials
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• v.16 no.3
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• pp.130-134
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• 2015

This research proposes the use of a composition modulated (ZrO₂)_x(Al₂O₃)_1-x film as a charge trapping layer for charge trap flash memory; this is possible when the Zr (Al) atomic percent is controlled to form a variable bandgap as identified by the valence band offsets and electron energy loss spectrum measurements. Compared to memory devices with uniform compositional (ZrO₂)_0.1(Al₂O₃)_0.9 or a (ZrO₂)_0.92(Al₂O₃)_0.08 trapping layer, the memory device using the composition modulated (ZrO₂)_x(Al₂O₃)_1-x as the charge trapping layer exhibits a larger memory window (6.0 V) at the gate sweeping voltage of ±8 V, improved data retention, and significantly faster program/erase speed. Improvements of the memory characteristics are attributed to the special energy band alignments resulting from non-uniform distribution of elemental composition. These results indicate that the composition modulated (ZrO₂)_x(Al₂O₃)_1-x film is a promising candidate for future nonvolatile memory device applications.

• International Journal of Automotive Technology
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• v.8 no.5
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• pp.543-553
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• 2007

It is becoming increasingly difficult for engines using conventional fuels and combustion techniques to meet stringent emission norms. The homogeneous charge compression ignition(HCCI) concept is being evaluated on account of its potential to control both smoke and NOx emissions. However, HCCI engines face problems of combustion control. In this work, a single cylinder water-cooled diesel engine was operated in the HCCI mode. Diesel was injected during the suction stroke($0^{\circ}$ to $20^{\circ}$ degrees aTDC) using a special injection system in order to prepare a nearly homogeneous charge. The engine was able to develop a BMEP(brake mean effective pressure) in the range of 2.15 to 4.32 bar. Extremely low levels of NOx emissions were observed. Though the engine operation was steady, poor brake thermal efficiency(30% lower) and high HC, CO and smoke were problems. The heat release showed two distinct portions: cool flame followed by the main heat release. The low heat release rates were found to result in poor brake thermal efficiency at light loads. At high brake power outputs, improper combustion phasing was the problem. Fuel deposited on the walls was responsible for increased HC and smoke emissions. On the whole, proper combustion phasing and a need for a well- matched injection system were identified as the important needs.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.351-352
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• 2007

Polymers submitted to thermo/electrical stress suffer from ageing that can drastically affect their functional behaviour. Understanding the physico/chemical processes at play during ageing and defining transport regimes in which these mechanisms start to be critical is therefore a prime goal to prevent degradation and to develop new formulation or new materials with improved properties. It is thought that a way to define these critical regimes is to investigate under which conditions (in terms of stress parameters) light is generated in the material by electroluminescence (EL). This can happen through impact excitation/ionization involving hot carriers or upon bi-polar charge recombination (a definition that excludes light from partial discharges, which would sign an advanced stage in the degradation process). After a brief review of the EL phenomenology under DC, we introduce a numerical model of charge transport postulating a recombination controlled electroluminescence. The model output is critically evaluated with special emphasize on the comparison between simulated and experimental light emission. Finally, we comment some open questions and perspectives.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.2239-2244
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• 2003

A new stratified charge combustion system has been introduced and developed for GDI engines. Before this new GDI system, the stratified mixture was formed by a high pressure swirl injector. But, the special feature of new system is employed of a thin fan-shaped fuel spray formed by a slit type nozzle. Also, this system has been adopted a shell-shaped piston cavity. We made high pressure gasoline injection system and investigated the fan-shaped spray characteristics such as spray tip penetration, spray angle, SMD and velocities of droplets using PDPA(Phase Doppler Particle Analyzer) system and spray visualization system to obtain the concept of the new design and the fundamental data for the next generation GDI system. The experiment was performed at the injection pressures of 5 and 9MPa under the atmospheric condition.

• Proceedings of the KIEE Conference
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• 1988.07a
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• pp.450-453
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• 1988

A numerical scheme is considered for computing charge distributions and drawing equipotential lines for multiconductor transmission lines with arbitrary cross sections. Two-dimensional integral equation superposed by the charges is numerically calculated by the method of moments. Here in Galerkin's method special pulses cut into halves chosen for expansion and testing functions facilitate the numerical computations in solving the integral equation. Numerical examples are given for some system of which the shell conductor is grounded as the reference zero of potential.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.53 no.8
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• pp.461-465
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• 2004

This paper analysed the induced current density by electric field of human body under the 765 kV transmission line considering permittivity and conductivity. As permittivity of human body is very high as $10^6$ at 60 Hz, special numerical computation technique in Surface Charge Method(SCM) for composite media with extremely different properties is applied to reduce calculation error of induced current density and electric field inside the human body. Calculation results show that the average of the induced current density inside human body is about 3mA/$m^2$, which is less than ICNIRP criterion (10mA/$m^2$).

• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.409-411
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• 1996

The purpose of this paper is construction of PMS with extension of consuming time of battery in the special vehicle system using exact Battery state of charge measurement algorithm. It is possible to use long distance control by RS-485, fast data processing VMEbus. Its computer simulation, experimental tests and application to special vehicle are described.

• Journal of Korean Medical classics
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• v.12 no.2
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• pp.248-265
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• 1999

The Special Method of Prescription, written by Ka-keum(柯琴) has scientific research for JungKyeong prescription. He takes charge of disease, syndrom, diagnotics of Exogenic febrile maladies(傷寒) and the level of doctors. There are six basic prescription with method of medical treatment; Kyejitang(桂枝湯) for persipiration, Chijashitang(梔子鼓湯) for vomiting, Seungkitang(承氣湯) for evaculation, Shihotang(柴胡湯) for harmanical progression, Sasimtang(瀉心湯) for cooling, Sayeoktang(四逆湯) for warming. In the first stage of exogenic febrile maladies. Kyejitang treat the flowing sweat, Mawhangtang(麻黃湯) treat the superficial fever and Daecheongryongtang(大靑龍湯) treat the anxious gitation About hydral-distention treatment, Sacheongryongtang(小靑龍湯) aim at vent hydral-distention with fever, Shipjotang(十棗湯) for cool hydral-distention without fever, Socheongryangtang(小靑龍湯) for moving hydral-distention, Oryeongsan(五苓散) for unmoving hydral-distentian and Jinmutang(眞武湯) far hydral-distentian with four extremities feel weight. The Special Method of Prescription discuss seven classification of herbo-prescription, the method acupuncture & moxibustion and other treatment.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.758-762
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• 2007

Revenue management is a new approach method to solve the problem of supply and demand, and one of fields which is diffused quickly at the service enterprise to use perishable-asset like the transportation business. It is based on multiple fare policy that discount charge reservation should be received if the benefit value of current discount fare is more than expected profit of the normal fare reservation it will be able to occur in future when suitable goods is sold to the customers at discount fare, at the time they want, and at assigned seat by controlling supply and demand from market. In this research, I will review on initial operation case for special class goods that the seat which is limited is assigned at some of train and portion of KTX for demand dispersion and new demand creation at peak time, put a limit in purchase conditions, and provides discounted fare. I will also try to find implication for strategic operation.

• Journal of the Korean Institute of Telematics and Electronics
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• v.14 no.2
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• pp.28-31
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• 1977

Normal modes of carrier waves due to longitudinal modulation in solids have been defined. The dispersion relationship of these waves in the presence of collision effects and thermal diffusion is derived and examined in detail. It is also shown that the carrier waves are reduced to the wellknown space-charge waves and electroacoustic hayes in special cases.