• Membrane and Water Treatment
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• 제10권2호
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• pp.155-163
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• 2019

The roles of polypropylene (PP) beads and pH on membrane fouling and treatment efficiency were investigated in a hybrid advanced water treatment process of tubular carbon fiber membranes (ultrafiltration (UF) or microfiltration (MF)) and PP beads. The synthetic feed including humic acid and kaolin flowed inside the membrane, and the permeated contacted the PP beads fluidized in the space between the membrane and the module with UV irradiation and periodic water back-flushing. In the hybrid process of UF ($0.05{\mu}m$) and PP beads, final resistance of membrane fouling ($R_f$) after 180 min increased as PP beads increased. The turbidity treatment efficiency was the maximum at 30 g/L; however, that of dissolved organic matters (DOM) showed the highest at PP beads 50 g/L. The $R_f$ strengthened as pH of feed increased. It means that the membrane fouling could be inhibited at low alkali condition. The treatment efficiency of turbidity was almost constant independent of pH; however, that of DOM showed the maximum at pH 5. For MF ($0.1{\mu}m$), the final $R_f$ was the minimum at PP beads 40 g/L. The treatment efficiencies of turbidity and DOM were the maximum at PP beads 10 g/L.

• 멤브레인
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• 제6권2호
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• pp.86-95
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• 1996

본 연구에서는1축 회전판형 한외여과막 모듈의 순수 투과율 예측모델과 기름 에멀션의 분리 특성 및 투과율 예측모델을 유도하였다. 1축 RDM은 한외여과막(UOP사, 직경 0.22m)으로 제작된 회전판막을 장착하여 $25^{\circ}C$에서 압력, 각속도($\omega$), 농도 변화에 따라 분리특성을 조사하였다. 회전판막의 각속도가 0에서 52.36rad/s로 증가할수록 회전판내 유체가 받는 원심력에 의한 압력 강하와 분리막 표면의 미끄럼 흐름에 의한 압력 강하로 순수 투과율은 최대 각속도에서 3.9% 감소하였다. 원심력과 미끄럼 흐름에 의한 압력 강하는 선속도(${\omega}r$)의 자승에 비례하였다. 회전판의 각속도가 52.36에서 2.62rad/s로 감소할 때 5% 절삭유의 투과율은 30.16% 감소하였고 농도가 낮을수록 막회전과 투과율에 미치는 영향은 적었다. 절삭유의 투과율(J; $kg/m^{2} \cdot s$)은 회전에 의한 압력 강하를 고려한 유효압력차($\Delta P_{T}$ ; Pa), 벌크농도($C_{B}$; %), 선속도($\omega$r; m/s) 등에 영향을 받으며 실험 결과에 저항 모델을 적용하여 다음과 같은 식을 유도하였다.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2002년도 International Meeting on Information Display
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• pp.504-507
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• 2002

We investigated electro-optic and ionic properties of twisted nematic cells by using control of chiral pitch. These properties are observed in practical experiment and simulations. C-V and V-T curve characteristics were obtained from three types of cells with d/p. It is shown that d/p ratio of short cells exhibit faster response time improved by 20% than normal cell. Also, inter-gray response time is improved each rise time and decay time. And, the increase of saturation voltage is happened because of the small twist angel change from initial state at high voltage near 5V. To compensate for longer black level tail, gamma curve index was varied from g = 2.2 to g = 2.7 in module status. Additionally, adding chiral dopant into TN cells improved ionic characteristics such as increasing VHR, Ion density and DC Hysteresis were decreased..

• 한국간호교육학회지
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• 제25권2호
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• pp.251-262
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• 2019

Purpose: This study aimed to identify the effect of a situational module learning course on critical thinking disposition and metacognition in sophomore nursing students. Methods: This study was a non-equivalent control-group pretest-posttest quasi-experimental design; the participants included 64 nursing students (32 in the experimental and 32 in the control group) from two Korean universities. Critical thinking disposition and metacognition between the control and intervention groups were measured before and after program participation. Data collection was conducted between September 1 and December 15, 2016. An independent t-test was used to determine differences in critical thinking disposition and metacognition between the groups and Pearson's correlations were measured for correlation with critical thinking disposition and metacognition. Results: The intervention group showed higher critical thinking disposition (t=3.16, p=.002); intellectual integrity (t=2.85, p=.006); and open-mindedness (t=3.30, p=.002) relative to those of the control group. However, there were no statistical differences in metacognition between the two groups (t=-0.14, p=.888). A significant positive correlation between metacognition and critical thinking disposition was found. (r=.62, p<.001). Conclusion: The situational module learning course developed in this study could be used to promote critical thinking disposition in nursing students.

• 마이크로전자및패키징학회지
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• 제15권1호
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• pp.7-18
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• 2008

This paper reviews the current development of an ultra-slim SiP for Radio Frequency (RF) application, in which three flip chips, additional passive components and Surface Acoustic Wave (SAW) filters are integrated side-by-side. A systematic investigation is carried out for the design optimization, process and reliability improvement of the package, which comprises several aspects: a design study based on the 3D thermo-mechanical finite element analysis of the packaging, the determination of stress, warpage distribution, critical failure zones, and the figuration of the effects of material properties, process conditions on the reliability of package. The optimized material sets for manufacturing process were determined which can reduce the number of testing samples from 75 to 2. In addition the molded underfilling (MUF) process is proposed which not only saves one manufacturing process, but also improves the thermo-mechanical performance of the package compared with conventional epoxy underfilling process. In the end, JEDEC's moisture sensitivity test, thermal cycle test and pressure cooker tests have also been carried out for reliability evaluation. The test results show that the optimized ultra-slim SiP has a good reliability performance.

• 한국인터넷방송통신학회논문지
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• 제18권2호
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• pp.27-32
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• 2018

본 논문에서는 W-대역 초소형 레이다용 송수신모듈을 설계 및 제작하였다. 제안하는 광대역 마이크로스트립-도파관 전이구조를 이용하여 설계 및 제작 오차를 줄였으며, 전이구조 당 1 dB 이하의 삽입손실 및 제작의 신뢰성을 제공하였다. 이중편파 모노펄스 특성을 가지는 초소형 레이다에 직접 적용하기 위해 28 dBm의 높은 출력을 가지는 한 채널의 송신모듈을 설계 및 제작하였다. 또한 13.5 dB의 낮은 잡음지수 및 최대 17 dBm의 높은 입력 P1dB를 가지는 6채널의 수신모듈을 개발하였다. 본 논문에서 제시한 W-대역 송수신모듈을 이용하여 초소형 레이다에 적용하여 이중 편파 모노펄스 신호를 바로 처리 가능하리라 예상된다.

• Journal of Power Electronics
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• 제11권2호
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• pp.179-187
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• 2011

This paper proposes a MATLAB Simulink simulator for photovoltaic (PV) systems. The main contribution of this work is the utilization of a two-diode model to represent a PV cell. This model is known to have better accuracy at low irradiance levels which allows for a more accurate prediction of PV system performance. To reduce computational time, the input parameters are reduced to four and the values of $R_p$ and $R_s$ are estimated by an efficient iteration method. Furthermore, all of the inputs to the simulator are information available on a standard PV module datasheet. The simulator supports large array simulations that can be interfaced with MPPT algorithms and power electronic converters. The accuracy of the simulator is verified by applying the model to five PV modules of different types (multi-crystalline, mono-crystalline, and thin-film) from various manufacturers. It is envisaged that the proposed work can be very useful for PV professionals who require a simple, fast and accurate PV simulator to design their systems.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2009년도 춘계학술대회
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• pp.903-906
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• 2009

본 연구에서는 임베디드 시스템, 특히 블루투스 베이스밴드에서 사용이 가능한 고속 직렬 포트 인터페이스를 설계하였다. 인터페이스는 ARM 프로세서를 응용할 수 있는 AMBA APB에 호환될 수 있도록 설계하였으며, 8비트 형태로 외부 디바이스와 코프로세서 간 데이터와 명령을 전송할 수 있다. 오류 정정을 위하여, CRC를 적용하였고 멀티미디어 카드를 위한 인터페이스도 제공하였다. 설계한 직렬 포트 인터페이스는 자동합성하여 P&R을 수행하였다. 결과물은 Altera FPGA로 구현하였으며 25MHz에서 정상동작하였다.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2007년도 춘계학술발표회 초록집
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• pp.19-19
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• 2007

Recently, we have developed p-i-n hydrogenated amorphous silicon (a-Si:H) single junction (SJ) thin film solar cells with RF (13,56MHz) plasma enhanced chemical vapor deposition (PECVD) systems, and also successfully fabricated the mini-modules (>300$cm^2$), using laser scribing technique to form an integrated series connection, The efficiency of a mini-module was 7.4% (Area=305$cm^2$, $I_{SC}$=0.25A, $V_{OC}$=14.74V, FF=62%).

• 한국농공학회논문집
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• 제59권3호
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• pp.63-70
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• 2017

The purpose of this study was to calibrate the hydrologic parameters of SWAT model and analyze the daily runoff for the study watershed using SWAT-CUP. The Hardware watershed is located in Virginia, USA. The watershed area is $356.15km^2$, and the land use accounts for 73.4 % of forest and 23.2 % of pasture. Input data for the SWAT model were obtained from the digital elevation map, landuse map, soil map and others. Water flow data from 1990 to 1994 was used for calibration and from 1997 to 2005 was for validation. The SUFI-2 module of the SWAT-CUP program was used to calibrate the hydrologic parameters. The parameters were calibrated for the highly sensitive parameters presented in previous studies. The P-factor, R-factor, $R^2$, Nash-Sutcliffe efficiency (NS), and average flow were used for the goodness-of-fit measures. The applicability of the model was evaluated by sequentially increasing the number of applied parameters from 4 to 11. In this study, 10-parameter set was accepted for calibration in consideration of goodness-of-fit measures. For the calibration period, P-factor was 0.85, R-factor was 1.76, $R^2$ was 0.51 and NS was 0.49. The model was validated using the adjusted ranges of selected parameters. For the validation period, P-factor was 0.78, R-factor was 1.60, $R^2$ was 0.60 and NS was 0.57.