• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2002.03a
• /
• pp.145-153
• /
• 2002

A coastwise chemical tanker sailing at full speed has capsized in calm water and whole turing. In the precious paper, we investigated reasons of the accident by demonstrating the proper correction for the free surface effect of the liquid cargo and the bow-sinkage effect. In this paper, we also carry out model experiments of a transverse pressure under the seawater and an outward heel moment according to the heel angle and rudder angle, on the basis of radius of turning circle, ship's speed and drift angle of model ship occurring in turning. It is also shown that the flooding of seawater onto the deck occurring in turning generated a significant outward heel moment and the vertical distance between the center of gravity of the ship and the renter of lateral water drag.

• 한국전산유체공학회:학술대회논문집
• /
• 1999.05a
• /
• pp.106-112
• /
• 1999

In this article, combination of the FAS-FMG multi-grid method and the Krylov subspace method was presented in solving two dimensional driven-cavity flows. Three algorithms of the Krylov subspace method, CG, CGSTAB(Bi-CG Stabilized) and GMRES method were tested with MILU preconditioner. As a smoother of the pressure correction equation, the MILU-CG is recommended rather than MILU-GMRES(k) or MILU-CGSTAB, since the MILU-GMRES(k) preconditioner has too much computation on the coarse grid compared to the MILU-CG one. As for the momentum equation, relatively cheap smoother like SIP solver may be sufficient.

• Journal of computational fluids engineering
• /
• v.14 no.2
• /
• pp.46-51
• /
• 2009

The slip effect from the molecular interaction between fluid particles and solid surface atoms plays a key role in microscale fluid transport and heat transfer since the relative importance of surface forces increases as the size of the system decreases to the microscale. There exist two models to describe the slip effect: the Maxwell slip model in which the slip correction is made on the basis of the degree of shear stress near the wall surface and the Langmuir slip model based on a theory of adsorption of gases on solids. In this study, as the first step towards developing a general purpose numerical code of the compressible Navier-Stokes equations for computational simulations of microscale fluid flow and heat transfer, two slip models are implemented into a finite element numerical code of a simplified equation. In addition, a pressure-driven gas flow in a microchannel is investigated by the numerical code in order to validate numerical results.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 2002.10a
• /
• pp.474-480
• /
• 2002

Aspheric optical lenses and mirrors are widely used in recent. It is more difficult to manufacture and measure the aspherical optics compared to conventional spherical ones. The interferometric optical test is common for the measurement of spherical optical surface. But the application of the interferometry to the measurement of aspheric surface is difficult because it needs a precise null corrector and very careful environmental conditions such as keeping constant temperature, humidity, atmospheric pressure and vibrations. To enhance productivity of optics manufacturing on-machine measurement and correction has been developed in this study. For practical applications, robustness of the measurement method to environments is more important. For the purpose an optical OMM(On-Machine Measurement) system has been developed using Shack-Hartmann test which has robustness to the environment. The wavefront has been reconstructed from the measured data using the primary aberration polynomial function by least square fitting. The measured result of the developed only system gives the maximum deviation only in 200 nm from the result measured by a commercial Fizeau interferometer Wyko 6000.

• Proceedings of the Acoustical Society of Korea Conference
• /
• spring
• /
• pp.461-468
• /
• 2002

Prediction method of floor impact noise for light and heavy weight impact is described. Sound pressure level is predicted based on the impedance method. For floating floor system, noise reduction is studied assuming 1-D mass-spring system. It is found that comparisons of predictions and measurements show good agreements. However, certain correction factor is needed to predict noise reduction of floating floor system.

• Korean Journal of Bronchoesophagology
• /
• v.18 no.2
• /
• pp.41-44
• /
• 2012

Acquired tracheoesophageal fistula (TEF) can occur rarely from various causes. Recently, cuff-related tracheal injury after endotracheal intubation with the orotracheal tube and tracheostomy cannula is the most common etiology of nonmalignant TEF. Since cuff-related TEF is usually preventable with proper selection of the cuffed tube and close monitoring of cuff pressure. Although most patients present increased secretions, recurrent pneumonia, or coughing after swallowing, a high index of suspicion is required in patients at risk for developing a TEF. Surgical correction for the defectis required. In most cases, primary closure of the esophageal defect and tracheal resection and end-to-end anastomosis give the best results.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
• /
• 2003.11a
• /
• pp.185-190
• /
• 2003

The most shortcoming of metalhalide lamps is what the instant restarting cannot be realized when the arc tube is in the hot condition. The discharge starting voltage of arc tube in the hot condition is much higher than in the cold condition. Therefore it takes about five minutes to restart the metalhalide lamps, that is to say, it is possible to start when the pressure and the temperature are decreased. But, if the lamp is restarted in the hot condition, we must supply the high voltage pulse with 20kV at the both sides of lamp. The proposed electronic ballast is consist of a electromagnetic interference (EMI) filter, a power factor correction (PFC) circuit, a flyback converter, a half-bridge inverter, and a high voltage igniter circuit. By this composition we can restart the lamp with the voltage 20kV, even if the lamp is in the hot condition.

• Journal of Chest Surgery
• /
• v.22 no.5
• /
• pp.775-780
• /
• 1989

This study concerns the late results observed at follow-up[average: 32.5 months] of 23 patients, in whom Patent Ductus Arteriosus with pulmonary hypertension among 55 patients. They were operated from May 1984 to July 1987 in Chonnam University Medical School. There was predominance of woman [2.5:1]. No operative death occurred. All of patients subside preoperative symptoms, but 1 patient diagnosed recannalization of duct at follow-up. Systolic murmur was found over the pulmonary area in 5 patients [22 %], but it may be not related to systolic pulmonary arterial pressure[SPAP]. Also, SPAP were normalized in 74 % of patients and had mild hypertension in 26 % of patients. Although the patients had Patent Ductus Arteriosus with pulmonary hypertension, successful surgical correction was carried out safely in all instance but one, by ligation and facilitated by hypotensive anesthesia.

• Journal of Chest Surgery
• /
• v.21 no.4
• /
• pp.721-726
• /
• 1988

Congenital supravalvar aortic stenosis is an obstruction caused by localized or diffuse narrowing of the aortic lumen commencing immediately above the aortic valve. We experienced a case of diffuse supravalvar aortic stenosis involving ascending aorta from just above the sinuses of Valsalva to the proximal l cm of the innominate artery. Supravalvar aortic stenosis in this patient, in contrast to the form seen in infants and children, was not associated with mental retardation, peculiar faces or the syndrome of hypercalcemia. Diagnosis was confirmed by retrograde left heart catheterization and left ventriculography. Surgical correction was performed by the replacement of oval shaped Woven Dacron patch over the narrow segment of aorta under the cardiopulmonary bypass. Blood pressure was controlled sufficiently with some adjunct of Inderal postoperatively. The patient was discharged with much improvement.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.24 no.7
• /
• pp.907-915
• /
• 2000

The preconditioned Krylov subspace methods were applied to the incompressible Navier-Stoke's equations for convergence acceleration. Three of the Krylov subspace methods combined with the five of the preconditioners were tested to solve the lid-driven cavity flow problem. The MILU preconditioned CG method showed very fast and stable convergency. The combination of GMRES/MILU-CG solver for momentum and pressure correction equations was found less dependency on the number of the grid points among them. A guide line for stopping inner iterations for each equation is offered.