• 상하수도학회지
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• 제24권4호
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• pp.433-442
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• 2010

BER at different packing ratios of bio-ring media(BRM) was tested to investigate the effect of varying hydraulic retention time (HRT) and current density on the nitrate removal and current efficiency. In the preliminary batch mode experiment of BERs, current density was applied at 2.0 A/$m^2$, 4.0 A/$m^2$, 4.8 A/$m^2$, which correspond to the designation of reactor #1, #2, #3, respectively. The reactor #2 showed a highest nitrate removal rate of 162.0 mg $NO_3{^-}$-N/L/d, and the kinetics of nitrate removal rate was defined as the Zero order reaction. In the primary experiment of BERs, four BERs packed with BRM were operated in varying HRT and current, and the packing ratios of reactor #1, #2, #3 and #4 were 0%, 8%, 16%, 24%. respectively. This results of the experiments indicated that the nitrate removal rate and current efficiency were increased significantly cause of growing of autotrophic denitrification microorganisms on the surface of cathode and media by increasing of the current density and decreasing of HRT. However, The decreasing of nitrate removal rate and current efficiencies were observed in the condition of HRT of 5.25 hr and 4.8 A/$m^2$ of current density. With more increasing current density and decreasing of HRT, the hydrogen inhibition occurred at the surface of cathode. Moreover, nitrate removal rate by autotrophic denitrification microorganisms attached on the media surface was observed to be limited by no longer increasing dissolved hydrogen concentration of each reactor. In conclusion, the highest nitrate nitrogen removal and current efficiency could be achieved when the BER was operated at the conditions of 7 hr HRT, current density of 4.0 A/$m^2$, and 16% packing ratio. And it was found that the amount of nitrate removal by microorganisms attached on the surface of cathode and media (BRM) was 178.2 mg/L and 52.2 mg/L respectively. and the amount of nitrate removal per MLVSS was 0.435 g $NO_3{^-}$-N/g $MLVSS{\cdot}d$ and 0.336 $NO_3{^-}$-N/g $MLVSS{\cdot}d$.

• 한국자원식물학회지
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• 제10권4호
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• pp.401-410
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• 1997

본 연구는 최근 건강 및 저공해 식품으로 수요가 급증하고 있는 주요 산채류인 곰취의 품질 및 수량 제고와 연중 생산을 위한 양액재배 기술을 개발하고자 이에 알맞는 배지종류, 배지량, 재식밀도 둥을 구명 하는 일련의 시험을 수행하였다. 그 결과를 요약하면 다음과 같다. 1. 곰취의 양액재배시 펄라이트, 모래, 팽연화(膨軟化)왕겨 등 공시한 3종의 배지 중 팽연화(膨軟化) 왕겨가 가장 생육이 양호하고 수량도 높아 적정배지로 인정 되었는데 이에 대한 특성은 기존 배지인 펄라이트에 비해 진비중(眞比重), 공극율(孔隙率)의 차이가 없으면서 액상(液相) 비율(比率)이 44.3%로 높은 등 물리성이 양호하였으며 생왕겨에 비해서는 수분흡수율이 1.5배나 높아 왕겨를 배지로 사용할 경우 문제점이었던 수분 흡수 능력도 양호하였다. 곰취의 생육단계별 체내 질소함량은 생육초기인 정식후 20일경에는 1.42%로 공시 배지중 가장 낮았으나 생육후기로 갈수록 점차 높아져 정식후 60일경에는 생육초기에 비해 2.4배나 증가되었고 3종의 배지 중 가장 높았다. 곰취의 엽진(葉辰), 엽폭(葉幅), 엽수(葉數) 등 생육은 팽연화 왕겨 배지에서 가장 양호하였으며 다음으로 펄라이트, 모래 순이었다. 수량은 하계 및 동계재배 공히 팽연화(膨軟化) 왕겨에서 초기 수량은 다소 낮았으나 후기로 갈수록 높아져 기존배지인 펄라이트에 비해 각각 $15\sim29%$ 증수되는 경향이었다. 2. 배지량에 따른 생육 및 수량은 유의성이 인정되지 않아 경제성 및 재배의 안정성을 고려할 경우 105 $\iota/m^3$가 적정한 것으로 인정되었다. 3. 재식밀도별 수량은 밀식일수록 증수되는 경향으로 50주/$m^3$에서 가장 높아 적정재식 밀도로 판단되었는데 더 이상의 밀식은 정식작업이 불가능하였다.절편과 약에 있어서 생장조절물질(生長調節物質)에 대한 반응에 차이(差異)가 다소 있음을 알 수 있었다. 약유래 식물체의 염색체(染色體)조사결과 대부분이 2n=34이었으며, 소수(小數) (5.4%)가 4배체이었다.(畦幅) 50cm, 주간(株間) l0cm로 재배(栽培)하는 것이 효과적(效果的)이었다.糞肥料施用)은 15%, 유기질(有機質) 비료(肥料)는 26%, 3요소 시용(施用)은 17%가 각각(各各) 증수(增收)되었으나, 특히 퇴비시용(堆肥施用)에서 31% 증수(增收)되었고, 근피중(根皮重)은 무비구(無肥區) 151kg에 비(比)하여 퇴비(堆肥), 계분(鷄糞) 비료(肥料) 시용(施用)은 $42{\sim}49%$ 증수(增收)되어 모단(牡丹) 재배시(栽培時) 화학비료(化學肥料) 시용(施用)보다는 퇴비(堆肥) 등(等) 유기질(有機質) 비료(肥料) 시용(施用)이 효고적(效果的)이었다.DS-PAGE법(法)으로 단백질(蛋白質) 양상을 등숙시기별(等熟時期別)로 조사(調査)한 결과(結果) 두 계통간(系統間) 질적(質的)인 차이(差異)는 보이지 않았으나 시기별(時期別)로는 양적차이(量的差異)를 나타냈다.間)에는 부(負)(-)의 상관(相關)이 있다.($P{\leq}0.01%$). 5. NEL 및 starch value 환경온도(環境溫度)가 상승(上昇)됨에 따라 감소(減少)된다. 4 엽기(葉期) sorghum식물(植物)의 환경온도(環境溫度)를 달리 하였을 때 NEL가치(價値)는 각각(各各) 4.87MJ($30/25^{\circ}C$), 5.46MJ($25/20^{\circ}C$) 및 5.81MJ/kg($18/8^{\circ}C$)로 변(變)하여 고온(高溫)에서 net energy lactation 축적(蓄積)이 크게 감소(減少)되었다.다.

• 한국산업정보학회:학술대회논문집
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• 한국산업정보학회 2008년도 추계 공동 국제학술대회
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• pp.479-491
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• 2008

A "task network" is a type of social network that consists of experts who exchange professional help and advice regarding executing tasks. In this study, we investigate the task network used within the IS department of a national bank in Korea. We identify how this network moderates the influence of computer-mediated communication (CMC) technology on an individual s task performance. Size, density, and centrality were measured as the characteristics of a personal task networks. Size equates to the total number of colleagues who work with a specific member for a certain project. Density is the ratio of the number of actual relationships to the total number of available relationships. Centrality defines whether an individual s position is in the exact center of whole network, and is measured by betweenness centrality, meaning the position one member holds between others in a network. Our findings conclude that the conditions - the larger the size of the task network, the smaller its density and the higher its level of centrality - lead to more benefits of using CMC media. Further, this positive effect of CMC is more noticeable when it provides synchronicity.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.886-888
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• 2009

We fabricated flexible electronic paper display(EPD) by using toner particles on plastic (PC) substrate. We observed the relationship between contrast ratio and changes of rib structures. One is a fabrication of ribs on bottom substrate. The display with ribs on bottom substrate had higher contrast ratio about 46% than display with ribs on top substrate. The other is a change of density of rib. The less density of ribs fabricated, the higher the contrast ratio become.

• 한국환경기술학회지
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• 제19권6호
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• pp.493-502
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• 2018

수계의 조류발생 원인물질인 질소와 인을 제거할 목적으로 수처리용 EM 담체를 개발한 후, 물리적 특성에 대하여 검토한 결과는 다음과 같다. EM 담체를 제조하기 위한 점토 : 제올라이트 : 질석 : 활성탄의 배합비율은 10 : 2.5 : 0.1 : 2, 소성온도는 $700^{\circ}C$가 적합하였다. EM 담체의 공극률과 밀도는 39.98 %와 $1.13kg/m^3$, 질소와 인의 흡착효율은 69.3 %와 38.9 %, 증류수 담체의 공극률과 밀도는 37.80 %와 $1.11kg/m^3$, 질소와 인의 흡착효율은 62.5 %와 37.8 %로 나타났다. EM 담체가 증류수 담체에 비하여 질소의 흡착효율은 6.8 %, 인의 흡착효율은 1.1 %가 크게 나타났다. 담체의 질소와 인에 대한 흡착특성은 Freudlich 흡착등온식으로 표현이 가능하였다. 소성시간의 변화는 EM 담체를 성형할 때 질소의 인의 흡착효율에는 큰 영향을 미치지 못하였으나 담체의 강도에는 영향을 미칠 것으로 판단된다. 질소의 제거효율은 소성시간 4시간, 인의 제거효율은 소성시간 3시간에서 가장 우수하였다.

• 천문학회보
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• 제35권2호
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• pp.74.2-74.2
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• 2010

We investigate driven magnetohydrodynamic (MHD) turbulence by including the effects of expansion and collapse of background medium. The main goal is to quantify the evolution and saturation of strength and characteristic lengths of magnetic fields in expanding and collapsing media. Our findings are as follows. First, with expansion and collapse of background medium, the magnetic energy density per comoving volume does not saturate; either it keeps decreasing or increasing with time. The magnetic energy density relative to the kinetic energy density strongly depends on the expanding or collapsing rate. Second, at scales close to the energy injection (or driving) scale, the slope of magnetic field power spectrum shallows with expansion but steepens with collapse. Third, various characteristic lengths, relative to the energy injection scale, decrease with expansion but increase with collapse. We discuss the astrophysical implications of our findings.

• ETRI Journal
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• 제36권3호
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• pp.498-501
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• 2014

A C-band 50 W high-power microwave monolithic integrated circuit amplifier for use in a phased-array radar system was designed and fabricated using commercial $0.25{\mu}m$ AlGaN/GaN technology. This two-stage amplifier can achieve a saturated output power of 50 W with higher than 35% power-added efficiency and 22 dB small-signal gain over a frequency range of 5.5 GHz to 6.2 GHz. With a compact $14.82mm^2$ chip area, an output power density of $3.2W/mm^2$ is demonstrated.

• E2M - 전기 전자와 첨단 소재
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• 제8권5호
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• pp.558-563
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• 1995

Dynamic characteristics of TbFeCo magneto-optical recording media at 680nm wavelength region were studied by means of computer simulation of disc structure and optimization of process variables during sputter deposition. With the slightly reduced Kerr rotation angle due to the reduced wavelength of optical laser source, the improved recording density in TbFeCo magneto optical media showing the CNR greater than 50dB could be achieved by only adjusting the thickness of dielectric and the recording layers when the wavelength of light source is changed from 780nm to 680nm. In addition, the recording power margin of 5mW and the 2mW minimum recording power was realized, It was shown from the present study that the increase in laser power density demonstrated feasibility of low cost and low power laser diode with the reduced optimum recording power.

• Preventive Nutrition and Food Science
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• 제8권3호
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• pp.284-288
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• 2003

In this study, we investigated the effects of green tea and Pueraria radix tea on the production of Apo B$_{100}$ in Hep G$_2$ liver cells and on the expression of the low density lipoprotein (LDL) receptor. Treatment with green tea resulted in a 60.7% decrease on the Apo B$_{100}$ concentration in Hep G$_2$ cells. Pueraria radix tea decreased Apo B$_{100}$ concentration by 63.5% in Hep G$_2$ cells. Green tea and Pueraria radix tea significantly decreased Apo B$_{100}$ concentration by 64.8% and 61.8%, respectively, in the media. Treatment of the cells with green tea and Pueraria radix tea also significantly decreased the intracellular total cholesterol, but total cholesterol concentrations in the media increased by 26.4% (green tea) and 23.6% (Pueraria radix tea) above that measured in the media of control cells. The addition of green tea and Pueraria radix to the media of the Hep Gz cells increased the LDL receptor binding activities by 84.1% and 79.4%, respectively.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2007년도 추계 학술대회논문집
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• pp.249-257
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• 2007

A high resolution numerical method aimed at solving gas-liquid two-phase flow is proposed and applied to gas-liquid two-phase shock tube problem. The present method employs a finite-difference 4th-order Runge-Kutta method and Roe's flux difference splitting approximation with the MUSCL TVD scheme. By applying the homogeneous equilibrium cavitation model, the present density-based numerical method permits simple treatment of the whole gas-liquid two-phase flow field, including wave propagation and large density changes. The speed of sound for gas-liquid two-phase media is derived on the basis of thermodynamic relations and compared with that by eigenvalues. By this method, a Riemann problem for Euler equations of one dimensional shock tube was computed. Numerical results such as detailed observations of shock and expansion wave propagations through the gas-liquid two-phase media and some data related to computational efficiency are made. Comparisons of predicted results and exact solutions are provided and discussed.