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Your search keyword '"Jung, Taewon"' showing total 22 results
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22 results on '"Jung, Taewon"'

2. Radiation induced pemphigoid disease

Author

Kim, Jihyun, primary, Jung, Taewon, additional, Kim, Kyongjin, additional, Kim, KyungA, additional, Hong, Sangki, additional, Baek, Sukyung, additional, and Moon, Jeongbum, additional

Published
2020
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3. Thermal impedance extraction for bipolar transistors

Author

Zweidinger, David T., Fox, Robert M., Brodsky, Jonathan S., Jung, Taewon, and Sang-Gug Lee

Subjects
Bipolar transistors -- Research, Impedance (Electricity) -- Observations, Business, Electronics, Electronics and electrical industries
Abstract

A method efficiently extracts the thermal impedance parameters in narrow-base bipolar junction transistors (BJT's) and heterojunction BJT's. The method involves finding the fractional change in a base or collector current for the unit change in transistor temperature at constant base-emitter voltage. The observations of base current response to a collector voltage step enable the determination of thermal impedance. Multiple-pole models using measurement results are used for compact circuit modeling in SPICE.

Published
1996

7. Enhanced electron emission from carbon nanotubes through density control using in situ plasma treatment of catalyst metal.

Author

Choi, Jong Hyung, Choi, Sun Hong, Han, Jae-Hee, Yoo, Ji-Beom, Park, Chong-Yun, Jung, Taewon, Yu, SeGi, Han, In-Taek, and Kim, J. M.

Subjects
NANOTUBES, CARBON, ELECTRON emission
Abstract

We controlled the density of carbon nanotubes (CNTs) through in situ NH[sub 3] plasma pretreatment and investigated field emission properties with the density variation. Ni catalytic layer was transformed into small nanoparticles with NH[sub 3] plasma pretreatment time and power. As NH[sub 3] plasma pretreatment time was increased, the growth rate of grown CNTs was gradually decreased. Also, the density of CNTs reduced from 2 × 10[sup 9] to 8 × 10[sup 6]/cm² with an increase in NH[sub 3] plasma pretreatment time from 10 to 30 min for the Ni layer of 10 Å. With a decrease in the density of CNTs, the emission current density was increased and turn on electric field was decreased. We obtained large and uniform emission current (about 9 mA/emission area of 0.49 cm²) from CNTs film with the density of 8 × 10[sup 6]/cm². [ABSTRACT FROM AUTHOR]

Published
2003
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8. Determination of lifetime and surface recombination velocity of p-n junction solar cells and diodes by observing transients

Author

Lindholm, Fredrik A, Liou, Juin J, Neugroschel, Arnost, and Jung, Taewon W

Subjects
Electronics And Electrical Engineering
Abstract

The unified view of transient methods for the determination of recombination lifetime tau and back surface recombination velocity S presented here for silicon solar cells and diodes attempts to define limitations of existing methods and to evolve improvements. The presence of sizable junction capacitance for silicon devices under forward voltage invalidates the use of conventional open-circuit voltage decay (OCVD) and reverse recovery. This led Green (1983) to his method of compensated open-circuit voltage decay, in which the addition of an external resistor shunting the solar cell partially corrects for the presence of the junction capacitance. Setting this resistance to zero produces an electrical short-circuit current-decay method, which has the advantage of enabling determination of both tau and S. In an alternate approach, one may insert the functional dependence of the junction capacitance on forward voltage. This new method, denoted by the acronym OCVDCAP, enables the determination of tau with apparently greater accuracy than that obtained by previous methods utilizing voltage transients. But OCVDCAP has in common with the previous methods that it determines tau only and has practical utility only for determining tau of long-base devices. This means that it is useful only for thick base regions. In principle, however, it has an advantage over short-circuit current decay: it requires only pressure contacts, not ohmic contacts, and therefore may be used to determine tau after key processing steps in manufacturing.

Published
1987

21. Density control of carbon nanotubes using NH3 plasma treatment of Ni catalyst layer

Author

Choi, Jong Hyung, Lee, Tae Young, Choi, Sun Hong, Han, Jae-Hee, Yoo, Ji-Beom, Park, Chong-Yun, Jung, Taewon, Yu, SeGi, Yi, Whikun, Han, In Taek, and Kim, J.M.

Subjects
*CARBON, *NANOTUBES, *PLASMA-enhanced chemical vapor deposition
Abstract

The effect of NH3 plasma pre-treatment on the growth characteristics of CNTs was investigated. We observed that NH3 plasma pre-treatment etched and conglomerated Ni catalyst film, resulting in the formation of Ni nanoparticles. The aligned CNTs from the Ni nanoparticles were grown by plasma enhanced chemical vapor deposition (PECVD). As Ni film thickness decreased from 300 to 30 A˚, the size of Ni nanoparticles decreased about from 140 to 90 nm and the average diameter of CNTs became smaller. As the NH3 plasma power was increased, the density of Ni nanoparticles was decreased, leading to the decrease in the density of CNTs. [Copyright &y& Elsevier]

Published
2003
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22. Control of carbon nanotubes density through Ni nanoparticle formation using thermal and NH3 plasma treatment

Author

Choi, Jong Hyung, Lee, Tae Young, Choi, Sun Hong, Han, Jae-Hee, Yoo, Ji-Beom, Park, Chong-Yun, Jung, Taewon, Yu, Se Gi, Yi, Whikun, Han, In-Taek, and Kim, J.M.

Subjects
*NANOTUBES, *CARBON
Abstract

We controlled the size and distribution of catalytic Ni nanoparticles to control the density and diameter of carbon nanotubes (CNTs). With an increase in plasma power from 30 to 90 W for Ni layer of 30 A˚, the average diameter of particles decreased from 157 to 58 nm due to an enhanced etching effect. Size and distribution of Ni nanoparticles varied by plasma power, pre-treatment time and thickness of catalytic layer, resulting in the change in the density of grown CNTs. Density of CNTs reduced from 1×109 to 8×106 cm−2, depending on the pre-treatment condition. [Copyright &y& Elsevier]

Published
2003
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