• 상하수도학회지
• /
• 제13권2호
• /
• pp.95-104
• /
• 1999

A simulation of water hammer, introduced by abruptly varied motion of a pumping machine, was performed at a one of typical pumping station in Korea. Impact of hydraulic structure such as check valve, pressure relief valve and air valve in mitigating water hammer effect was estimated gradually. Method of characteristic was employed for the effective calculation of discharge and head. The relationship between various hydraulic structures and flow was properly integrated on the base of the method of characteristic. The methodology in this approach can provide significant contribution in decision making procedure for the design of hydraulic structure at a typical pumping station in Korea.

• 한국해양공학회지
• /
• 제11권4호
• /
• pp.102-110
• /
• 1997

A two dimensional shallow-water flow around a cavity driven by a sinusoidally oscillating external flow was studied numerically with an Ekman pumping model. A container model of "T" shape was constructed in the numerical computation for comparison with the experimental observation. The material transport in the external region is in good agreement with the experimentally recorded particle trajectories. It turns out that two large coherent vortices situated in the exterior region of the cavity are responsible for clockwise and counterclockwise drift motions, in large scale, of particles. The Ekman pumping model suggested in this study was found to be satisfactory.isfactory.

• 대한전기학회논문지
• /
• 제41권1호
• /
• pp.95-106
• /
• 1992

For commercial application of the MCFC, the life time of the MCFC should exceed 40,000 hours, But the life time of the state-of-the-art MCFC was limited to 15,000 hours. The main reasons of the life time limit can be classified as the deficiency of the electrolyte and cathode dissolution. It has been found that the electrolyte deficiency is caused by the continuous evaporation of the electrolyte. However a recent reaserch shows that an electrolyte pumping phenomenon, which implies, the migration of the electrolyte through the gasket material of the external gas manifold, is also the reason of the electrolyte deficiency. Due to the electrolyte pumping phenomenon, positive end cell of the stack suffers the electrolyte deficiency and negative end cell of stack is flooded with electrolyte. Therefore, the cell performance is degraded. The author invented a new manifoldcasing, which prevents the contact between the wet seal and the gasket of the manifold, and gives a complete elimination of an electrolyte pumping effect.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2003년도 춘계학술대회 논문집
• /
• pp.1294-1297
• /
• 2003

With the development of medical field, many kinds of operations have been performed on human articulation. Arthroscopic surgery, which has Irrigation Pumping System for security of operator vision and washing spaces of operation, has been used for more merits than others. In this paper, it is presented that the research on a reliable control algorithm of the pumping system instrument for arthroscopic surgery. Before clinical operation, the flexible artificial articulation model is used for realizing the model the most same as human's and the algorithm has been exploited for it. This system is considered of the following; limited sensing point, dynamic effect by compliance, time delay by fluid flow and so on. The system is composed with a pressure controller, a regulator for keeping air pressure, an airtight tank that can have distilled water packs, artificial articulation and a measuring system, and has controlled by the feedback of pressure sensor on the artificial articulation. Also the system has applied to Smith Predictor for time delay and the parameter estimation method for the most suitable system with both the experiment data and modeling. In this paper, the pressure error that is between an air pressure tank and an artificial articulation was measured so that the system could be presumed and then the controller had developed for performing State-Feedback. Finally, the controller with a real microprocessor has realized. The confidence of system can be proved by applying this control algorithm to an artificial articulation experiment material.

• 한국지반공학회논문집
• /
• 제15권6호
• /
• pp.111-120
• /
• 1999

투수성 중간복토재로 인한 침출수 흐름 거동과 누적수위 저감을 위해 양수정을 이용한 수직배수공법의 적용 가능성을 흐름 수치해석 프로그램인 MODFLOW를 이용하여 분석하였다. 현장 양수시험과 순간충격시험으로부터 획득한 투수계수와 저류계수를 이용하여(장연수 외, 1999) 현장의 수리상황을 수치적으로 검증한 후, 매립지에서 누적수위를 저감하기 위한 양수정의 최적양수율, 영향반경, 수평드레인의 효용성을 분석하였다. 본 수치해석 결과 대상지역의 지반조사결과(장연수 외, 1999)에서도 나타났던 저투수성의 중간 복토재로인한 매립지내의 수직흐름을 방해하는 차수효과가 다시 확인되었다. 단정 양수시 120 ton/day까지 가능하였던 양수율은 수평드레인 추가후 300 ton/day까지 증가하였으나 드레인 길이가 시간-수위강하 곡선에 큰 영향을 주지는 않았다.

• 한국광학회지
• /
• 제13권5호
• /
• pp.449-454
• /
• 2002

$^85Rb\;D_1$ 전이선의 바닥준위 $F_g$=2에서 여기준위 $F_e$=3 전이를 이용하여 열린 원자계에서의 전자기 유도 흡수 현상을 관측하고, 전자기 유도 흡수에서의 비결맞음 펌핑 효과를 조사했다. 비결맞음 광원의 편광과 세기의 변화에 따른 전자기 유도 흡수에 대한 연구를 통해 비결맞음 광원의 편광에 따라서 자기부준위들 사이의 원자밀도 분포의 변화를 유도할 수 있고, 이러한 원자밀도 재분포 효과에 의해서 전자기 유도 흡수의 정도가 달라짐을 확인하였다

• 한국수자원학회:학술대회논문집
• /
• 한국수자원학회 2022년도 학술발표회
• /
• pp.450-450
• /
• 2022

The study aims to develop scenarios for efficient groundwater use using existing wells in order to prepare for an eventual drought. In the recent decades, droughts are not only intensifying, but they are also spreading into territories where droughts used to be less intense and relatively infrequent. With the increasing disaster, efficient groundwater use is urgently needed not only to prevent the problem of groundwater depletion but also drought risk reduction. Thus, the research addressed the problem of efficient aquifer use as source of water during drought and emergencies. The research focused on well network system applied to Yanggok-ri in Korea using simulation models in visual MODFLOW. The approach consists to variate groundwater pumping rate in the most important wells used for irrigation across the study area and evaluate the pumping effect on water level fluctuation. From the evaluation, the pumping period, appropriate pumping rate of each well and the most vulnerable wells are determined for a better groundwater management. The project results divide the study area into two different regions (A and B), where the wells in the region A (western part of the region) show a crucial drop in water level from May to early July and in august as consequence of water pumping. While wells in region B are also showing a drawdown in groundwater level but relatively less compare to region A. The project suggests a scenarios of wells which should operate considering water demand, groundwater level depletion and daily pumping rate. Well Network System in relevant project, by pumping in another well where water is more abundant and keep the fixed storage in region A, is a measure to improve preparedness to reduce eventual disaster. The improving preparedness measure from the project, indicates its implication to better groundwater management.

• 한국통신학회논문지
• /
• 제29권5A호
• /
• pp.484-491
• /
• 2004

L-band EDFA는 작은 평균밀도 반전율에서 동작하기 때문에 C-b란d에서 상대적으로 높은 흡수율로 인해 펌프 효과를 가지게 된다. 본 논문에서는 980nm의 펌프 입력 광 파워, C-band 펌프 파장 및 입력 광 파워에 따라 펌프 효과에 대해 논하고자 한다. 즉, C-band 펌프광의 흡수 또는 후방 자연방출광의 흡수라는 두 가지 다른 메카니즘을 통해 펌프 효과를 야기 시키게 된다. 또한 동일한 소 신호 이득 조건 하에서 L-band 신호 입력 광에 의한 포화 특성 (포화 광출력, 잡음지수에 있어서 장파장의 C-band 펌프가 양호한 것으로 나타난다. 전광 고정이득 L-band EDFA에서 C-band발진의 효과를 검토한 결과 L-band발진에 비해서 개선된 특성은 없는 것으로 나타난다.

• 한국전산유체공학회지
• /
• 제15권4호
• /
• pp.40-45
• /
• 2010

The flow rate is higher in ACEO micro-pumps with step electrodes than in micro-pumps with planar asymmetric electrodes. In the present study, numerical simulations were made of a ACEO micro-pump with step electrodes to investigate the effects of electrode design parameters on the pumping flow rate. The electrical charge at the electrodes, the fluid flow, and potential were solved, taking into account the finite size of ions, that is, the steric effect. This effect is recognized to be capable of quantifying the electrical charge more accurately in the electrical double layer subject to high voltages. Geometrical parameters such as heights, widths, and gaps of three-dimensional electrodes were optimized to enhance the pumping flow rate. Moreover, the effect of amplitude and frequency of AC was studied.

• 대한토목학회논문집
• /
• 제12권1호
• /
• pp.141-150
• /
• 1992

급격한 도시화로 인해 기존의 배수체계에 의한 내수배제에 문제가 발생하게 되고, 이에 따른 홍수 발생시의 내수침수 피해가 도시지역 홍수의 새로운 문제로 대두되고 있는 실정이다. 본 연구에서는 기존의 배수체계 중 유수지 및 우수배제 펌프장의 안전도를 검토하였다. 펌프조작에 있어서는 증수부와 감수부에 따라 우수배제 펌프를 조작하는 기준이 기존 펌프보유대수로도 홍수대처능력을 현재보다 월동하게 증가시킬 수 있음을 수치적으로 확인하였다. 또한 유수지내 유입량과 펌프조작에 대한 민감도 분석을 실시하여 펌프 한대가 담당하는 적정 유입량의 범위를 검토하였다. 연구결과 서울특별시 관내 57개소의 유수지 및 우수배제 펌프장중 10년 빈도의 설계호우에 대해서도 60% 정도만이 안전한 것으로 나타나 이에 대한 근본적 대책이 시급한 것으로 판명되었다.