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沈遇培,宋在偶 弘益大學校 科學技術硏究所 1999 科學技術硏究論文集 Vol.10 No.1
Laboratory flume experiments to investigate the characteristics of the flow and local scour around two circular shapes of bridge pier on a foundation in a straight channel are performed. This study examines the influnce of different foundation elevation on nonuniform pier. The results show that the effect of maximum reduction of scouring develope when the top elevation of foundation is located at 0.5D below evevation streanbed. The aspect of scour depth is similar when the top elevation of foundation is placed deeper than the maxium scour depth. Also, for two circular bridge pier on a foundation, second pier develope lower scour depth than uniform pier.
宋在偶,沈遇培 弘益大學校 科學技術硏究所 1998 科學技術硏究論文集 Vol.9 No.1
Laboratory flume experiments to investigate the characteristics of the flow and local scour around circular shapes of bridge pier in a straight channel are performed. This study examines the effect of a asymmetry circular collar devices for controlling the depth of scour. As the ratio of asymmetry increased, the scour depth decreased. In addition, the maximum reduction of scouring is about 67% for CASE3 and CASE4. The prevention of scouring is most effective when the asymmetry collar for all case is placed at 0.1h below river bed.
Performance increase for an open-cathode PEM fuel cell with humidity and temperature control
Ou, Kai,Yuan, Wei-Wei,Choi, Mihwa,Yang, Seugran,Kim, Young-Bae Pergamon Press 2017 International journal of hydrogen energy Vol.42 No.50
<P><B>Abstract</B></P> <P>Water and thermal management of an open-cathode proton electrolyte membrane (PEM) fuel cell is developed in this study. A bubble humidifier, which is one of the balance of plant (BOP) systems, is newly installed to control the humidity of the fuel cell. A multiple-input-multiple-output (MIMO) fuzzy controller is developed, and proven to be superior in controlling a strong non-linear dynamical fuel cell system in real-time. According to the fuzzy control stratagem, the two main control objectives are the axial fan speed control for regulating temperature and the solenoid valve on/off control of the bubble humidifier for humidity variation. First, the axial fan speed is controlled to keep the fuel cell temperature within the desired point. Second, the bubble humidifier is utilized to humidify the inlet hydrogen to manage the water content of a membrane. After simulating the electrochemical and thermal fuel cell models, the optimal operating conditions are determined. A fuzzy logic controller with five inputs and two outputs is constructed and utilized to regulate the temperature and relative humidity of an open cathode fuel cell in real time. Results show that the proposed fuzzy controller effectively increased the output power of PEM fuel cell.</P> <P><B>Highlights</B></P> <P> <UL> <LI> An advanced control is developed for controlling fuel cell temperature and humidity. </LI> <LI> An open-type fuel cell model is developed to find optimal operating points. </LI> <LI> About 10% of power increase is achieved using our method. </LI> </UL> </P>
Ou, Kai,Yuan, Wei-Wei,Choi, Mihwa,Yang, Seugran,Jung, Seunghun,Kim, Young-Bae Elsevier 2018 International journal of hydrogen energy Vol.43 No.32
<P><B>Abstract</B></P> <P>This research develops an efficient and robust polymer electrolyte membrane (PEM) fuel cell/battery hybrid operating system. The entire system possesses its own rapid dynamic response benefited from hybrid connection and power split characteristics due to DC/DC buck-boost converter. An indispensable energy management system (EMS) plays a significant role in achieving optimal fuel economy and in a promising running stability. EMS as an indispensable part plays a significant role in achieving optimal fuel economy and promising operation stability. This study aims to develop an adaptive supervisory EMS that comprises computer-aided engineering tools to monitor, control, and optimize the performance of the hybrid power system. A stationary fuel cell/battery hybrid operating system is optimized using adaptive-Pontryagin's minimum principle (A-PMP). The proposed algorithm depends on the adaptation of the control parameter (i.e., fuel cell output power) from the state of charge (SOC) and load power feedback. The integrated model simulated in a Matlab/Simulink environment includes the fuel cell, battery, DC/DC converter, and power requirements models by analyzing the three different load profiles. Real-time experiments are performed to verify the effectiveness of EMS after analyzing the simulated operating principle and control scheme.</P> <P><B>Highlights</B></P> <P> <UL> <LI> An adaptive power management strategy is developed for fuel cell/battery. </LI> <LI> Power split between two sources is done through DC/DC converter control. </LI> <LI> Minimization of fuel and constant charge level of battery are proved experimentally. </LI> </UL> </P>
실험연구 : Lidocaine 또는 Bupivacaine과 Enflurane 투여가 Histamine에 의한 기니픽 기도평활근 수축에 미치는 영향
권오경 ( Ou Kyoung Kwon ),배현민 ( Hyun Min Bae ) 대한마취과학회 2006 Korean Journal of Anesthesiology Vol.51 No.6
Background: The effects of local and inhalation anesthesia on the contraction of the tracheal smooth muscle have been reported. However, when inhalation and local anesthesia are administered simultaneously, their effects on the contraction of the airway smooth muscle are not well known. Therefore, this study evaluated the effects of lidocaine, bupivacaine, with or without enflurane, on the histamine induced tracheal smooth muscle contraction in guinea pigs. Methods: Isolated tracheal rings of guinea pigs were suspended in Krebs solution. The contractions were recorded isometrically using a transducer. A contraction was induced by histamine (10-5 M). Enflurane (1 MAC) was administered for 15 min after administering the histamine. The cumulative dose responses of the lidocaine and bupivacaine (10-8 M, 10-7 M, 10-6 M, 10-5 M, 10-4 M, and 10-3 M), enflurane-lidocaine and enflurane-bupivacaine groups were checked. Results: The contraction by histamine were inhibited by lidocaine (10-4 M and 10-3 M) and bupivacaine (10-5 M, 10-4 M and 10-3 M). In addition, the contractions were inhibited more significantly in the bupivacaine group (10-7 M, 10-6 M, 10-5 M, 10-4 M and 10-3 M) after administering enflurane. Conclusions: Lidocaine and bupivacaine inhibited the contractions induced by histamine. The contractions by bupivacaine were further inhibited after administering enflurane. (Korean J Anesthesiol 2006; 51: 733~7)