인삼은 반음지성 식물로 해가림을 위해 지붕 및 벽에 해가림막 시설이 필요하다. 하지만 해마다 강해지는 강풍이나 태풍으로 인해 많은 농가시설물이 피해를 입고 있으며, 특히 인삼재배시설의 경우 시설물이 길게 하나로 연결되어 있어 피해가 크다. 이러한 피해를 방지하기 위해서는 인삼재배시설에 가해지는 풍하중을 평가하여 그것에 견딜 수 있도록 내풍설계를 해야 한다. 이 연구에서는 관행식과 후주연결식 인삼재배시설의 구조골조에 대한 풍하중을 산정하기 위해 필요한 지붕 및 벽 해가림막의 순압력계수를 풍동실험을 통해 정량적으로 평가하였다. 이 연구결과는 인삼재배시설에 대한 내풍설계의 기초자료가 될 것이다.

The ozonation process has been widely used for drinking water disinfection around the world. Recently, the pressurized ozone contactor, in which the side stream typed ozone injection method is installed, has been applied to water treatment system. In this study, numerical calculations were conducted to compare prototype and screw-type ozone contactors based on hydraulic effectiveness in more details. The prototype ozone contactor was already installed and operated in domestic water treatment plant, and the screw-type is the suggested one for improving ozone contact efficiency installing the screw plate to the prototype. Screw turn numbers of screw plate were changed as 3, 5, 7 and 9, respectively for numerical simulation. The CT(concentration of disinfectant in mg/L times time in minutes) value was considered as one of the options for evaluating disinfection ability. From the results, it could be concluded that the performance of the screw-type is higher than that of the protype contactor by controlling the variable T as the tracer time. Also, Morill index of the screw-type(turn numbers = 5 ) appeared to be lower than the other.

The effect of oxygen pressure on the synthesis of ZnO nanowires by means of melt-oxidation of an Al-Zn mixture was investigated. The samples were prepared in oxygen ambient for 1 h at 1,000˚C under oxygen pressure ranging from 0.5 to 100 Torr. ZnO nanowires were formed at oxygen pressures lower than 10 Torr. As the oxygen pressure increased from 0.5 to 10 Torr, the width of the nanowires increased, but their length decreased. The ZnO nanowires had a needle shape, which became gradually thinner toward the tip. X-ray diffraction patterns showed that the nanowires had a hexagonal wurtzite structure. However, ZnO nanowires were not observed when the oxygen pressure increased from 10 Torr to 100 Torr. In roomtemperature cathodeluminescence spectra of the ZnO nanowires, the intensity of ultra-violet emission at 380 nm increased with decreasing oxygen pressure, which indicated that the lower the oxygen pressure, the better the crystallinity of the ZnO nanowires.

Coal-tar pitch, a feedstock which can be heat-treated to create graphite, is composed of very complex molecules. Coal-tar pitch is a precursor of many useful carbon materials (e.g., graphite, carbon fibers, electrodes and matrices of carbon/carbon composites). Modified coal-tar pitch (MCTP) was prepared using two different heat-treatment methods and their properties were characterized and compared. One was prepared using heat treatment in nitrogen gas; the other was prepared under a pressure of 350 mmHg in air. The MCTPs were investigated to determine several properties, including softening point, C/H ratio, coke yield, formation of anisotropic mesophase and viscosity. The MCTPs were subject to considerable changes in chemical composition due to condensation and polymerization in the used-as-received coal-tar pitch after heat-treatment under different conditions. The MCTPs showed considerable increases in softening point, C/H ratio, and coke yield, compared to those of as-received coal-tar pitch. The MCTP formed by heat-treatment in nitrogen showed isotropic phases below 350˚C for 1 h of soaking time. However, MCTP heat-treated under high pressure (350 mmHg) showed isotropic phases below 300˚C, and showed anisotropic phases above 350˚C, for 1 h of soaking time. The viscosity of the MCTPs increased with increase in their softening points.

Using a high-rise building water piping after hydrostatic test of the reliability of the leak to be completed if the pressure is maintained until the leak is not commercially available considered. Due to the nature of high-rise buildings and the construction period will take several years from the lower levels of use of the water supply and fire fighting water pipe construction is in progress, the order of which I do most of the first pipe to the construction and more than three years. So kind of riser pipe is complete, install the valve in the basement by installing an automatic pump to maintain a constant pressure after hydrostatic test and after each floor plumbing piping is complete, the progress of the hydrostatic test without undergoing a separate branch pipe the valve is opened automatically when the number of the pressing pressure of the structure. I kind of do and keep working pressure of pipe until the completion of the construction work to keep the damage to human error when it is intended to prepare. In winter, the frost protection and an alternative to drainage water pipe is damaged or deformed, even if unaware of the finishing work to the building, the use of the damage caused by a leak in a after construction of finish work to be expected. Alternative to reduce this damage if the pressure test without fear of freezing to help maintain long-term commercial pressures may be considered.

본 연구는 낙동강 하구역의 사주섬 중 최서측에 위치하는 진우도를 대상으로 실험구를 구축한 후 해안선의 법선 방향으로 정점 5곳을 선정하여 2012년 3월부터 2013년 1월까지 약 11개월간 관측된 수온, 전기전도도, 압력값을 이용하여 지하수위 변동해석을 하였다. 1) 지하수의 수온, 염분, 수위변동과 조위, 파랑, 강수량 등의 외력조건과의 시계열 분석 및 상관분석을 통하여, 조간대정점에서는 파랑 및 조위의 영향, 식생 및 모래지반 정점에서는..

The purpose of this study was to determine the effect of gait initiation training on gait and center of pressure (CoP) during gait initiation in stroke patients. Twenty-three subjects were randomly assigned to either an experimental group (EG) or a control group (CG). The EG received gait initiation training with increased CoP posterior distances the maximum the rear on gait training. The CG received general gait training. Both groups received training three times a week over a period of four consecutive weeks. The figures for CoP distances the maximum the rear, CoP distances time the mover the maximum the rear, the Tinetti Performance-Oriented Mobility Assessment (POMA), and gait velocity were recorded both before and after the training sessions for both groups. The EG’s results for CoP distances the maximum the rear, CoP distances time the mover the maximum the rear, and POMA improved after training (p<.05). In terms of the rate of change of CoP distances the maximum the rear, the EG demonstrated a significantly higher increase (p<.05) than did the CG. The results of this study suggest that increased CoP distances the maximum the rear affect the gait initiation and gait performance of stroke patients. Further studies with a larger sample size are necessary to verify the accuracy of the results of this study.

본 연구의 목적은 지지체의 친수화가 압력지연삼투(Pressure retarded osmosis, PRO)막의 투과특성에 미치는 영향에 대해서 알아보고자 하였다. 소수성 지지체인 폴리에스테르를 친수성 고분자인 셀룰로오스 용액을 사용하여 친수화도를 조절하였다. 지지체의 친수화 특성만을 파악하기 위해서 지지층 없이 동일한 활성층을 사용하여 PRO 막 투과 특성을 비교하였다. 사용된 활성층은 1,4-dioxane과 cellulose tri-acetate (CTA, 13 wt%)를 사용하여 제조하였으며, 5 kgf/cm2 압력 하에서 행한 PRO 성능 평가의 경우 투과도가 친수화된 지지체를 사용한 경우와 친수화되지 않은 경우에 각각 1.2 L/m2hr와 0.8 L/m2hr로 친수화된 지지체를 사용할 경우 약 50% 투과량이 증가되는 특성을 보였다. 그러나 셀룰로오스 농도 변화에 따른 지지체의 친수화도 증가가 투과량 변화를 가져오지는 않았다. 이는 지지체를 친수화하기 위해 사용된 셀룰로오스의 농도가 증가함에 따라 지지체의 기공이 막히는 현상에 기인한 것으로 보인다. 이러한 결과를 통해 정삼투공정에서 투과유량을 높이기 위해서는 지지체로서 친수성 소재를 사용하여 분리막을 제조함과 동시에 지지체 기공을 유지하는 것이 중요함을 확인하였다.

In this study, we have modeled a ship or marine structure into a rectangular resistance body and tried to examine surrounding flow characteristics and pressure distributions behind the resistance body experimentally and investigated pressure characteristics by a 3-dimension numerical simulation. As a result, the numerical simulation predictions were shown to compare well with PIV data. and the perpendicular velocity component behind x/H=0 varies in size with the recycle flow shapes formed from the influence of the resistance body, but generally it shows a negative distribution and there is a decreasing pattern as it goes to the down part.

A three dimensional numerical analysis was performed to study the PEMFC performance characteristics. Operating pressure and operating temperature were selected as simulation parameters. Operating pressure was varied as 1, 2, 3, 4, and 5 atm. Operating temperature was varied as 323, 333, 343, 353, and 363 K. For a constant cell voltage condition, the maximum current density was obtained at operating pressure of 5 atm and operating temperature of 323 K. As operating pressure increases, current density increases because concentration of reactant gases increases. As operating temperature increases, current density decreases because concentration of reactant gases decreases due to high overpotential condition for the considered PEMFC.

사질토 지역에서의 내부수위 변동은 매질을 통한 물의 이동 및 변동에 대한 다양한 정보를 제공하며, 특히 자연해빈에서의 내부수위 변동은 그 지역의 지형적, 환경적, 생태적, 수문학적인 변화를 결정짓는 중요한 요소이다.본 연구는 낙동강 진우도 해안선의 법선 방향으로 관측점 5곳을 선정하여 2012년 3월부터 2013년 1월까지 약10개월간의 수온, 전기전도도, 압력값을 관측하였으며,관측값을 토대로 진우도 내의 내부수위 변동특성을 알아보고자 하였다.

Axial flow fan under certain condition may stall. The rise in pressure across the impeller blade of an axial flow fan depends on the angle of attack. At a low back pressure, the air volume will be large and the angle of attack is small. In this study, the time dependent Navier-Stokes equations are numerically solved in large size axial-flow fan with groove

본 연구에서는 지름이 일정한 하나의 직선 관형 막을 가정하여 그 단위구간의 투과속도에 대한 물질수지를 세웠으며 이것을 기초로 하여 파이프의 정상상태 식과 함께 비선형 연립 2차 미분방정식을 이루었다. 이러한 관형 막의 압력손실을 표현한 연립방정식은 비선형이므로 Gauss-Seidel method와 같은 반복법에 의해서 해결될 수 있다. 이러한 수치해를 나타내기 위해 모사 알고리즘을 제시하였다. 또한 투과수는 운전 조건의 변화에 따라 변하므로 각 조건에서의 연립 방정식의 해를 수치적으로 적분하여 해결하였다. 모사의 결과를 검증, 해석하기 위해서 실제 중공사막과 유사한 관형 막을 사용하여 실험을 진행하였다. 본 연구에서는 중공사막을 유체가 흐를 때 발생하는 압력손실, 유량, 그리고 투과수의 관계를 분석적 방법을 이용해 제시하였고 이러한 이론적 기초를 바탕으로 실제 기공을 가진 막에 적용하여 그 정확성을 실험을 통하여 비교하였다.