• Journal of Chest Surgery
• /
• 제24권7호
• /
• pp.732-738
• /
• 1991

Membranous obstruction of the inferior vena cava[IVC] is a rare congenital anomaly that may present clinical features of Budd-Chiari syndrome caused by chronic obstruction of hepatic drain. We have experienced a case of IVC obstruction caused by hour-glass constriction and membrane in its center. Operative correction was accomplished using profound hypothermia [20%] and total circulatory arrest of 26 minutes. This technique permitted resection of membrane with direct vision and removal of thrombus of IVC and hepatic vein. After then constricted IVC was repaired with autologous pericardial patch. Total circulatory arrest was used intermittently for good visual field. Postoperative course was smooth and postoperative angiography showed unobstructed flow through the IVC in spite of slight constriction of cavoatrial junction and nearly complete disappearance of collateral vessels.

• Journal of Electrochemical Science and Technology
• /
• 제5권3호
• /
• pp.82-86
• /
• 2014

This work presents the variation of formic acid oxidation on Pt depending on hydrodynamic condition using a rotating disk electrode. As the rotating speed increases, the oxidation rate of formic acid decreases under voltammetric and chronoamperometric measurements. The coverages of poison formed from formic acid during the chronoamperomertric investigations decrease when the rotating speed increases. As the roughness factor of Pt electrode surface increases, on the other hand, the current density of formic acid oxidation increases. These observations are discussed in terms of the tangential flow along Pt electrode surfaces generated by the rotating disk electrode, which reduces a contact time between formic acid and a Pt site, thus the formic acid adsorption.

• 한국세라믹학회지
• /
• 제43권4호
• /
• pp.203-206
• /
• 2006

Polyacrylonitrile (PAN) nanofibers, which are pH-sensitive and exhibit soft actuation as a linear actuator and artificial muscles, were prepared by electrospinning to investigate the effect of viscosity on the morphology of PAN fibers. Experimental results revealed that higher viscosity is critical for the formation of unbeaded nanofibers because surface tension is almost constant throughout the experiment. Uniform, smooth, and continuous fibers with diameters of about 700 nm were achieved for the 10 wt% PAN fibers at a flow rate of 0.5 mL/h and an electric field of 0.875 kV/cm.

• Wind and Structures
• /
• 제7권2호
• /
• pp.71-88
• /
• 2004

In this paper the capacity of Covariance Proper Transformation (CPT) analyses to provide information about the wind loading mechanisms of bluff bodies is investigated through the application to square cylinders. CPT is applied to the fluctuating pressure distributions on a single cylinder, as well as on a pair of cylinders in the tandem and side by side arrangements, with different separations. Both smooth and turbulent flow conditions are considered. First, through the analysis of the contributions of each CPT mode to the total fluctuating aerodynamic forces, a correspondence between modes and aerodynamic components is sought, which is then verified through examination of the mode shapes. When a correspondence between modes and aerodynamic components is found, an attempt is made to separate the different frequency contributions to the aerodynamic forces, provided by each mode. From the analyses it emerges that (a) in most cases each mode is associated to one single force component, that (b) retaining a limited number of modes allows reproducing the aerodynamic forces with a rather good accuracy, and that (c) each mode is mainly associated with one frequency of excitation.

• 설비공학논문집
• /
• 제19권7호
• /
• pp.529-536
• /
• 2007

The perforated type element for a heat recovery ventilation system has been studied to improve the performance. Four holes of diameter of 6mm are punched out for each flow channel to break the boundary layer development and increase the turbulence. KS cooling and heating conditions and test procedures are applied for study. The efficiencies are compared to those of the typical element with smooth surface. For cooling operations, the temperature, latent and enthalpy efficiencies increase 2.5%, 18% and 8%, respectively. For heating operations, the temperature, latent and enthalpy efficiencies increase 3%, 5% and 3.2%, respectively.

• 한국정밀공학회지
• /
• 제31권5호
• /
• pp.395-401
• /
• 2014

Development of five axis tool grinding machine and CAD/CAM systems increase tool design flexibility. In this research, investigated are cutting characteristics of ball-end mill with different helix angle. Special WC ball-end mills with $0^{\circ}$, $10^{\circ}$, $20^{\circ}$, $30^{\circ}$ helix angles are designed and used in various cutting tests. Machining performance according to helix angle variation is evaluated from cutting forces, surface roughness, tool wear, produced chip shape, and vibration characteristics. The ball-end mill with $10^{\circ}$ helix angle shows the best cutting performance due to appropriate chip load distribution and smooth chip flow. This research can be used for cutting edge geometry optimization and novel design of ball-end mill.

• 한국원자력학회:학술대회논문집
• /
• 한국원자력학회 1997년도 추계학술발표회논문집(1)
• /
• pp.475-480
• /
• 1997

In order to conduct the effective integration of computer-aided conceptual design for integrated nuclear power reactor, not only is a smooth information flow required, but also decision making fur both conceptual design and construction process design must be synthesized. In addition to the aboves, the relations between the one step and another step and the methodologies to optimize the decision variables are verified, in this paper especially, that is, scaling laws and scaling criteria. In the respect with the running of the system, the integrated optimization process is proposed in which decisions concerning both conceptual design are simultaneously made. According to the proposed reactor types and power levels, an integrated optimization problems are formulated. This optimization is expressed as a multi-objective optimization problem. The algorithm for solving the problem is also presented. The proposed method is applied to designing a integrated sub-critical reactors.

• 지역연구
• /
• 제8권2호
• /
• pp.1-9
• /
• 1992

One of the problems associated with the current system of land development projects implemented by the public sector in Korea is that various service facilities are not ready in time for the occupation of residential dwelling. A major cause of the problem is the lack of financial arrangements which would smooth the cash-flow of the suppliers of the facilities during the project period. In this paper we present two schemes which will contribute to the optimal provision of service facilities by easing the financial constraint facing the land developers and suppliers of the facilities. The first scheme involves channeling a fraction of profits from a land development project and of the proceeds of mandatory sales of Type II National Housing Bonds as a loan to the suppliers of the service facilities. The second scheme considers the participation of the private sector in the project as a member of a consortium comprising the Korea Land development Corporation, the National Housing Fund, and private developers. It is proved that each scheme is superior to the current system. as well as entailing a very small cost.

• 설비공학논문집
• /
• 제3권3호
• /
• pp.168-175
• /
• 1991

Experiments have been conducted to measure the overall heat transfer coefficient for gas-solid fluidized double pipe heat exchanger with finned tube. The average particle diameters of alumina are used in 0.4, 0.5, 0.6 and 0.9mm. And the effects of average particle diameter, static bed height and flow velocity on overall heat transfer coefficient have been investigated. Also the heat transfer effect of fluidized bed was compared with that of single phase forced convection and that of heat exchanger with smooth tube.

• 통합자연과학논문집
• /
• 제10권1호
• /
• pp.14-19
• /
• 2017

Neuromedin, a neuropeptide, which is involved in various functions that include contractile activity on smooth muscle, controlling the blood flow and ion transport in the intestine, increased blood pressure and regulation of adrenocortical function. It is involved in the pathophysiology of various immune mediated inflammatory diseases like asthma. In this study, we have performed protein-protein docking analysis of neuromedin U - neuromedin U receptor 1 complex. We have developed homology models of neuromedin U, and selected a reliable model using model validation. The model was docked with the receptor model, to analyse the crucial interactions of the complex. This study could be helpful as a tool in developing novel and potent drugs for the diseases related with neuromedin U receptor 1.