• 한국환경과학회지
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• 제14권11호
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• pp.1027-1033
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• 2005

The treatment of styrene vapor was carried out using the biofilter packed with loess/polyurethane composite during continuous operation of 74 days. The microorganisms were adapted within 2-3 days under the experimental conditions of inlet concentration and empty bed contact time (EBCT). At 200 sec of EBCT, the removal efficiency of styrene was 100\% with 200 ppmv of inlet concentration, while $92\%$ with 400 ppmv of inlet concentration. The biofilter showed the stable removal efficiencies of over $74\%$ under the EBCT range from 300 to 75 sec at the 150 ppmv of inlet styrene concentration. The maximum capacity of styrene removal for the biofilter packed with loess/polyurethane was $29g/m^3/hr$. During continuous operation of 74 days, pH of the drain water changed slightly and the pressure drop through the biofilter column was below $45\;mmH_2O/m$.

• 대한전자공학회논문지TC
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• 제41권11호
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• pp.87-91
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• 2004

모바일 단말기는 터치패드 방식의 문자 입력을 한다. 따라서 사용자에게 긴 입력을 요구할 때 불편한 환경을 제공한다. 따라서 이미지의 특정 지점을 마우스로 선택함으로 문자입력을 대신하여 인증을 함으로써 편리한 환경을 제공한다. 보안을 제공하기 위하여 초기 이미지에 따른 이미지의 배열 정보 및 입력된 값을 해시코드화 하여 인증 및 키교환이 안전하게 이루어진다. HASH와 SEED 암호화 알고리즘을 적용하여 효율적이고, 전송 메시지의 무결성을 보장하며 내부 참여자에 의한 정보 유출이 있더라도 안전한 전자지불 프로토콜 시스템을 설계 및 구현하였다.

• Transactions on Electrical and Electronic Materials
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• 제14권1호
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• pp.32-35
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• 2013

In this paper, a manufacturing process was developed for fabricating high-quality AlGaN/GaN high electron mobility transistors (HEMTs) on silicon carbide (SiC) substrates. Various conditions and processing methods regarding the ohmic contact and pre-metal-deposition $BCl_3$ etching processes were evaluated in terms of the device performance. In order to obtain a good ohmic contact performance, we tested a Ti/Al/Ta/Au ohmic contact metallization scheme under different rapid thermal annealing (RTA) temperature and time. A $BCl_3$-based reactive-ion etching (RIE) method was performed before the ohmic metallization, since this approach was shown to produce a better ohmic contact compared to the as-fabricated HEMTs. A HEMT with a 0.5 ${\mu}m$ gate length was fabricated using this novel manufacturing process, which exhibits a maximum drain current density of 720 mA/mm and a peak transconductance of 235 mS/mm. The X-band output power density was 6.4 W/mm with a 53% power added efficiency (PAE).

• 한국전기전자재료학회논문지
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• 제22권11호
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• pp.910-917
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• 2009

We have designed a new structures of Junction Field Effect Transistor(JFET) using SILVACO simulation to improve electrical properties and process reliability. The device structure and process conditions of Si control JFET(Si JFET) were determined to set cut off voltage and drain current(at Vg=0 V) to -0.46 V and $300\;{\mu}A$, respectively. Among many design parameters influencing the performance of the device, the drive-in time of p-type gate is presented most predominant effects. Therefore we newly designed SiGe JFET, in which SiGe layers were placed above and underneath of Si-channel. The presence of SiGe layer could lessen Boron into the n-type Si channel, so that it would be able to enhance the structural consistency of p-n-p junction. The influence of SiGe layer could be explained in conjunction with boron diffusion and corresponding I-V characteristics in comparison with Si-control JFET.

• Nuclear Engineering and Technology
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• 제52권8호
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• pp.1764-1770
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• 2020

The present work was mainly concerned with studying the operation of RC-phase shift oscillator based on MOSFET type 2N6660 under the influence of different temperature levels ranging from room temperature (25 ℃) up-to135 ℃ and gamma-irradiation up-to 3.5 kGy. In this concern, both the static (I-V) characteristic curves of MOSFET devices and the output signal of the proposed oscillator were recorded under ascending levels of both temperature and gamma-irradiation. From which, it is clearly shown that the drain current was decreased from 0.22 A, measured at 25 ℃, down to 0.163 A, at 135 ℃. On the other hand, its value was increased up-to 0.49 A, whenever the device was exposed to gamma-rays dose of 3.5 kGy. Considering RC-phase shift oscillator, the oscillation frequency and output pk-pk voltage were decreased whenever MOSFET device exposed to gamma radiation by ratio 54.9 and 91%, respectively. While, whenever MOSFET device exposed to temperature the previously mentioned parameters were shown to be decreased by ratio 2.07 and 46.2%.

• KIEAE Journal
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• 제9권2호
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• pp.99-106
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• 2009

The noise in apartment buildings are major factor that determine the quality of indoor noise environment. Particularly, the noise from children's running footsteps and plumbing noise have caused the residents who live in decrepit apartment houses to uncomfortable environment. And as time go by, sound performance are getting worse according to the aging of the facilities. So this study deals with the plans to improve the sound performance of decrepit apartment house. To compare the noise reduction, we measured the heavy-weight impact sound level and plumbing noise level before and after changes the measurement conditions. As the results of measurements, the heavy-weight impact sound level were decreased when stiffness reinforcement were installed on slab. Especially the sound level were decreased 2.1-7.6dB in 50-80Hz of low frequency range. Instead of PVC pipe system, cast iron pipe and triple elbow drain pipe systems were installed. Noise level were decreased 15dB(A) in 250Hz. Noise level of pipe system's on the slab is less than under slab one. On the contrary water saving stool showed increasing the noise level.

• 전기전자학회논문지
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• 제14권3호
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• pp.219-223
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• 2010

본 연구에서는, PVA를 게이트 유전체로 이용하여 백 게이트 (back-gate) 구조의 HgSe 나노입자 박막트랜지스터를 플라스틱 기판위에 제작하였다. 제작된 박막트랜지스터는 $100^{\circ}C$ 에서 5분 동안의 열처리 과정을 통하여 이동도 $16\;cm^2$/Vs, 전류 점멸비 $10^4$의 우수한 특성을 나타내었다. 열처리에 따른 표면 거칠기의 감소가 소자의 전기적 특성향상의 원인이라는 것을 AFM 이미지를 통하여 확인 할 수 있었다. 0.6%의 strain을 기판에 인가하면서 기판의 휘어짐에 따른 전류변화를 관찰하였다.

• ETRI Journal
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• 제39권2호
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• pp.292-299
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• 2017

We propose pulse-mode dynamic $R_on$ measurement as a method for analyzing the effect of stress on large-scale high-power AlGaN/GaN HFETs. The measurements were carried out under the soft-switching condition (zero-voltage switching) and aimed to minimize the self-heating problem that exists with the conventional hard-switching measurement. The dynamic $R_on$ of the fabricated AlGaN/GaN MIS-HFETs was measured under different stabilization time conditions. To do so, the drain-gate bias is set to zero after applying the off-state stress. As the stabilization time increased from $ 0.1{\mu}s$ to 100 ms, the dynamic $R_on$ decreased from $160\Omega$ to $2\Omega$. This method will be useful in developing high-performance GaN power FETs suitable for use in high-efficiency converter/inverter topology design.

• 한국의류산업학회지
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• 제5권5호
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• pp.539-544
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• 2003

The purpose of this study is to research source of soil which is available for non-detergent course, and to develop optimum non-detergent course of washing machine for water soluble soil. The water soluble soil such as grape juice, soy bean paste and soy sauce were easily removed from the fabric but the oil soluble soils such as sesame oil and steak sauce were insurfficiently removed in washing solution without detergent. In the absence of detergent, amount of residual soils increased linearly with increasing number of soiling and washing. To search optimum conditions of washing for non-detergent course, the effect of temperature, washing time and washing method on detergency of soil in non-detergent washing solution was examined. The optimum washing temperature and washing time for non-detergent course were about $40^{\circ}C$, and 7 minutes, respectively. And in the non-detergent washing solution, midterm drain-resupply of water during washing process was good for removal of water soluble soil.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2010년도 제39회 하계학술대회 초록집
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• pp.99-99
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• 2010

Recently, amorphous transparent oxide semiconductors (TOS) have been widely studied for many optoelectronic devices such as AM-OLED (active-matrix organic light emitting diodes). The TOS TFTs using a-IGZO channel layers exhibit a high electron mobility, a smooth surface, a uniform deposition at a large area, a high optical transparency, a low-temperature fabrication. In spite of many advantages of the sputtering process such as better step coverage, good uniformity over large area, small shadow effect and good adhesion, there are not enough researches about characteristics of a-IGZO thin films. In this study, therefore, we focused on the electrical properties of a-IGZO thin films as a channel layer of TFTs. TFTs with the a-IGZO channel layers and Y2O3 gate insulators were fabricated. Source and drain layers were deposited using ITO target. TFTs were deposited on unheated non-alkali glass substrates ($5cm{\times}5cm$) with a sintered ceramic IGZO disc (3 inch $\varnothing$, 5mm t), Y2O3 disc (3 inch $\varnothing$, 5mm t) and ITO disc (3 inch $\varnothing$, 5mm t) as a target by magnetron sputtering method. The O2 gas was used as the reactive gas. Deposition was carried out under various sputtering conditions to investigate the effect of sputtering process on the characteristics of a-IGZO thin films. Correlation between sputtering factors and electronic properties of the film will be discussed in detail.