• Journal of Mushroom
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• v.20 no.4
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• pp.235-240
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• 2022

This study aimed to replace the imported Chinese complete medium for Lentinula edodes with a newly-developed complete medium that is suitable for export as well. Three media compositions that supported fast mycelium growth and higher density, compared to that in the control, were chosen. Culture in the T13 medium reduced the incubation period for 'Nongjingo' by 12 days and for 'Cham-aram' by 10 days, compared to that required for the control; in addition, the number of days required for browning was greatly reduced for both varieties. The quantity of each mixed medium was increased according to the composition from the 1^st to the 5^th cycle by 5.9% for 'Nongjingo' and 12.6% for 'Cham-aram' in T13, compared to that in the control. A mixed medium comprising oak sawdust + Douglas fir sawdust + corn flour (40:40:20, v/v) was selected as the most suitable complete medium.

• Journal of Surface Science and Engineering
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• v.41 no.5
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• pp.214-219
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• 2008

Indium tin oxide (ITO) films were deposited on PET substrate by RF superimposed DC magnetron sputtering using ITO (doped with 10 wt% $SnO_2$) target. Substrate temperature was maintained below $750^{\circ}C$ without intentionally substrate heating during the deposition. The discharge voltage of DC power supply was decreased from 280 V to 100 V when superimposed RF power was increased from 0 W to 150 W. The electrical properties of the ITO films were improved with increasing of superimposed RF power. In the result of cyclic bending test, relatively high mechanical property was obtained for the ITO film deposited with RF power of 75 W under DC current of 0.75 A which could be attributed to the decrease of internal stress caused by decrease in both deposition rate and plasma impedance.

• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.1948-1950
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• 2004

가속기 연구소에서 개발한 고전압 대전류용 Seal-off TVS (Triggered Vacuum Switch)의 특성을 시험 하는 것을 목적으로 하고 있다. 제작한 TVS는 양전극과 음전극이 교대로 고정된 간격으로 각각 3개의 전극으로 배열되어 있으며 전극은 사다리꼴 모양으로 되어있고 트리거 시스템과 개스를 흡수하는 게터가 내부에 설치되어 있다. 제작한 스위치 내부는 약 $10^{-7}$ torr의 진공상태를 유지하고 있으며 세라믹 챔버를 사용하여 Seal-off 상태로 설계, 제작하였다. 스위치 시험장치는 200 ${\mu}F$, 22 kV 6개를 병렬로 연결한 커패시터 뱅크와 $20{\mu}H{\sim}160{\mu}H$의 탭변환 인덕터와 $0.1{\Omega}{\sim}0.5{\Omega}$ 의 저항을 이용하여 시험 장치를 구성하였다. TVS의 시험에서 에너지 최고 전달량은 74 C 이었으며 이때 인가전압은 30 kV, 최대 전류는 100 kA, 펄스폭은 1${\sim}$2 ms이었다. 본 논문은 제작한 스위치의 전기적인 특성 시험한 결과에 대하여 논하고자 한다.

• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.2131-2133
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• 2004

모세관 전기영동 및 전기화학적 검출 시스템을 마이크로 시스템에 적용하여 ITO 유리기판과 polydimethylsiloxane (PDMS)로 제작하였다. 제작된 모세관 전기영동 및 전기화학적 검출 시스템은 일회용으로 사용가능하며 전기화학적 검출에 아주 적합한 특성을 보인다. 모세관 전기영동 및 전기화학적 검출 시스템은 주입과 분리 채널 (80 ${\mu}m$ 폭 ${\sim}$ 40 ${\mu}m$ 깊이)을 가진 PDMS 층과 유리기판 위에 검출 전극으로 사용되는 ITO가 형성된 층으로 구성된다. PDMS 층과 ITO 유리 기판은 UV-$O_3$ cleaner를 사용하여 접합하였다. 완충용액은 10 mM 2-(N-morpholino)ethanesulfonic acid (MES)를 사용하였고 분석물질은 1 mM 농도의 dopamine과 1 mM 농도의 catechol을 사용하였다. 60 V/cm 전계로 주입 및 분리를 하였으며 작업전극과 기준전극 간의 전위는 +600 mV로 유지하며 분석물질의 농도에 비례하는 전류량법으로 측정하였다. 전기화학적 검출 회로는 천기영동 전계의 간섭으로부터 분리하였다. 10 mM MES 완충용액에서 바탕 전류의 크기가 ${\sim}$10 pA 일 때 측정전류 값은 10 nA이다. 측정된 피크 값은 기존의 Au 전극과 비교하여 선택성, 감도, 분해능이 유사한 특성을 보여준다.

• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.1778-1780
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• 2004

Microwave heating system of KSTAR consists of ECH and LHCD. ECH and LHCD offer the reliability of operation in the beginning of plasma formation and non-inductive current drive for long time steady state operation with maintaining MHD stability, respectively. LHCD demands 5 GHz of frequency and consists of c-band waveguide, 4-port circuitor, dry dummy load, dual directional coupler, E-bend, arc detector. Our system is a lineup type pulse modulator that has 45 kV of output pulse voltage, 90 A of pulse current, 4 us of pulse width. 1:4 step-up pulse transformer, 7 stages of PFN and thyratron tube (E2V, CX1191D) are used in this modulator. The purpose of this paper is to show the modulator design and experimental result.

• Proceedings of the KIEE Conference
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• 1995.07c
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• pp.1290-1292
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• 1995

A cylindrical-post magnetron sputtering system was designed for pipe inner coating. The discharge condition was depended on the gas pressure, magnetic field and pipe diameter. At given discharge current, discharge voltage increased a little with pipe diameter. The electron temperature and floating potential increased with magnetic field. The impact ion energy on the pipe increased with bias voltage. The TiN thin-film of $2{\mu}m$ thickness was formed by cylindrical-post magnetron sputtering system under the conditions of the pressure of 5mTorr, the applied voltage of 700V, the discharge current of 500mA, the magnetic field of 300G, and the bias voltage of -100V.

• Journal of Electrical Engineering and Technology
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• v.11 no.6
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• pp.1763-1768
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• 2016

This paper presents the electrical characteristics of the gallium nitride (GaN) current aperture vertical electron transistor (CAVET) by using two-dimensional (2-D) technology computer-aided design (TCAD) simulations. The CAVETs are considered as the alternative device due to their high breakdown voltage and high integration density in the high-power applications. The optimized design for the CAVET focused on the electrical performances according to the different gate-source length ($L_{GS}$) and aperture length ($L_{AP}$). We analyze DC and RF parameters inducing on-state current ($I_{on}$), threshold voltage ($V_t$), breakdown voltage ($V_B$), transconductance ($g_m$), gate capacitance ($C_{gg}$), cut-off frequency ($f_T$), and maximum oscillation frequency ($f_{max}$).

• Korean Journal of Materials Research
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• v.19 no.9
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• pp.499-503
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• 2009

Transparent ITO films were deposited on a polycarbonate substrate with RF magnetron sputtering in a pure argon (Ar) and oxygen ($O_2$) gas atmosphere, and then post deposition electro annealed for 20 minutes in a $4{\times}10^{-1}$ Pa vacuum. Electron bombardment with an accelerating voltage of 100 V increased the substrate temperature to $120^{\circ}C$. XRD analysis of the deposited ITO films did not show any diffraction peaks, while electro annealed films indicated the growth of crystallites on the (211), (222), and (400) planes. The sheet resistance of ITO films decreased from 103 to $82{\Omega}/\square$. The optical transmittance of ITO films in the visible wavelength region increased from 85 to 87%. Observation of the work function demonstrated that the electro-annealing increased the work function of ITO films from 4.4 to 4.6 eV. The electro annealed films demonstrated a larger figure of merit of $3.0{\times}10^{-3}{\Omega}^{-1}$ than that of as deposited films. Therefore, the electro annealed films had better optoelectrical performances than as deposited ITO films.

• The Korean Journal of Physiology and Pharmacology
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• v.7 no.4
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• pp.247-250
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• 2003

A simple and sensitive assay method was developed for cefepime in human plasma using high performance liquid chromatography (HPLC). Cefepime and cefadroxil (the internal standard) were extracted from heparinized human plasma by simple deproteination with perchloric acid. The extract was injected into an Atlantis dC18 column ($250{\times}4.6$ mm; particle size $5{\mu}m$, Waters) and the column was eluted with methanol and 0.01 M dihydrogen phosphate at pH 3.0 (15：85 v：v) as a mobile phase at a flow rate of 0.7 mL/min. Linearity was confirmed for the range 0.25 to $200{\mu}L/mL$ and the limit of quantitation was $0.25{\mu}L/mL$. The retention times were 10.2 min and 13.4 min for cefepime and cefadroxil, respectively. This method was successfully applied to a pharmacokinetic study of cefepime in plasma from bone marrow transplant patients.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.1-6
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• 2001

In this article, the fundamental concept, characteristics and application potentials of coreless printed-circuit-board (PCB) transformers are described. Coreless PCB transformers do not have the limitations associated with magnetic cores, such as the frequency limitation, magnetic saturation and core losses. In addition, they eliminate the manual winding process and its associated problems, including labor cost, reliability problems and difficulties in ensuring transformer quality in the manufacturing process. The parameters of the printed windings can be precisely controlled in modern PCB technology. Because of the drastic reduction in the vertical dimension, coreless PCB transformers can achieve high power density and are suitable for applications in which stringent height requirements for the circuits have to be met. A transformer's power density of $24W/cm^2$ has been reported in a power conversion application. When used in an isolation amplifier application, coreless PCB transformers tested so far enable the amplifier to achieve a remarkable linear frequency range of 1MHz, which is almost eight times higher than the frequency range of 120kHz in existing Integrated-Circuit products. PCB materials offer extremely high isolation voltage, typically from 15kV to 40kV, which is higher than many other isolation means such as optocouplers. It is envisaged that coreless PCB transformers can replace traditional core-based transformers in some industrial applications. Their application potentials deserve more attention and exploration.