• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2003년도 춘계학술대회
• /
• pp.2066-2070
• /
• 2003

This experimental study describes the propagation characteristics and suppression of the impulse noise emitted from the exit of a perforated pipe attached to the open end of a simple shock tube. The experiment is performed through the systematic change of the shock wave Mach number and the geometrical parameters such as the porosity, hole diameter and length of the perforated pipe. The experimental results for the near and far sound field are presented and explained in comparison with those for a straight pipe. The results obtained show that for the near sound field the impulse noise strongly propagates toward to the pipe axis, but for the far sound field the impulse noise uniformly propagates toward to the all directions, indicating that the directivity pattern is almost same regardless of the pipe type. Moreover, the noise reduction performance of perforated pipe depends upon the condition of sound field. For the near sound field the perforated pipe has a little performance to suppress the impulse noise, but for the far sound field the perforated pipe has little performance to suppress the impulse noise.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2001년도 추계학술대회논문집B
• /
• pp.438-443
• /
• 2001

Plate impingement of the impulse wave discharged from the open end of a duct is numerically investigated using a CFD method. Harten-Yee Total Variation Diminishing method is used to solve the unsteady, compressible flow governing equations. The Mach number, the flat plate inclination and the distance between the duct exit and inclined flat plate are changed to investigate their effects on the impinging flow field. The impulse wave impingement on the inclined flat plate depends on Mach number $M_s$ and the plate inclination $\psi$. The pressure distributions on the inclined flat plate show that for a small r/D, the peak pressure at the center of an inclined flat plate decreases with an increase in the plate inclination $\psi$ in the range of $\psi$ from $45^{\circ}$ to $60^{\circ}$ but for a large r/D, the peak pressure decreases with an increase in $\psi$ in the range of $\psi$ from $75^{\circ}$ to $90^{\circ}$. It is also found that for all of r/D, the peak pressure at the center of an inclined flat plate has a maximum value in $\psi=90^{\circ}$.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2001년도 추계학술대회논문집B
• /
• pp.432-437
• /
• 2001

A computational work of the impulse wave which is discharged from the open end of a pipe is compared to the Lighthill's aeroacoustics theory. The second-order total variation diminishing(TVD) scheme is employed to solve the axisymmetric, compressible, unsteady Euler equations. The relationship between the initial compressure wave form and the resulting impulse wave is characterized in terms of the peak pressure. The overpressure, pressure gradient and wavelength of the initial compression wave are changed to investigate the influence of the initial compressure wave form on the peak pressure of impulse wave. The results obtained show that for the initial compression wave of a large wavelength and small pressure gradient the peak pressure of the impulse wave depends upon the wavelength and pressure gradient of compression wave, but for the initial compression wave of a short wavelength and large pressure gradient the peak pressure of the impulse wave is almost constant regardless of the wavelength and pressure gradient of compression wave. The peak pressure of the impulse wave is increased with an increase in the overpressure of the initial compression wave. The results from the numerical analysis are well compared to the results from the aeroacoutics theory with a good agreement.

• Animal cells and systems
• /
• 제13권2호
• /
• pp.119-125
• /
• 2009

Mammalian hibernation is a type of natural adaptation that allows organisms to avoid harsh environment and to increase the possibility of survival. To investigate the molecular link between circadian and hibernating rhythms in the greater tube-nosed bats, Murina leucogaster, we set out to identify circadian genes that are expressed in bats, with specific focus on the PAS domain by using PCR-based screens. We could isolate a eDNA clone, designated as LPAS1, that encodes a protein of 521 amino acid residues. LPAS1 is closely related with CLOCK family with the highest homology to human CLOCK. Based on RT-PCR analyses, LPAS1 transcripts are ubiquitously present in tissues from both summer active and winter dormant periods. Given that LPAS1 is a member of the bHLH-PAS protein superfamily but lacks polyglutamine transactivation domains, it is likely to function as a repressor for endogenous CLOCK to hinder its roles in promoting transcription. Our result will open a new avenue to further examine the functional interconnection between the circadian clock and the circannual clock such as mammalian hibernation.

• 한국소음진동공학회논문집
• /
• 제12권1호
• /
• pp.48-56
• /
• 2002

A computational work of the impulse wave which is discharged from the open end of a pipe is compared to the Lighthill\`s aeroacoustics theory. The second-order total variation diminishing(TVD) scheme is employed to solve the axisymmetric, compressible, unsteady Euler equations. The relationship between the initial compressure wave form and the resulting impulse wave is characterized in terms of the peak pressure. The overpressure, pressure gradient and wavelength of the initial compression wave are changed to investigate the influence of the initial compressure wave form on the peak pressure of impulse wave. The results obtained show that for the initial compression wave of a large wavelength and small pressure gradient the peak pressure of the impulse wave depends upon the wavelength and pressure gradient of compression wave, but for the initial compression wave of a short wavelength and large pressure gradient the peak pressure of the impulse wave is almost constant regardless of the wavelength and pressure gradient of compression wave. The peak pressure of the impulse wave is increased with an increase in the overpressure of the initial compression wave. The results from the numerical ana1ysis are well compared to the results from the aeroacoutics theory with a food agreement.

• 한국전산유체공학회:학술대회논문집
• /
• 한국전산유체공학회 2008년도 춘계학술대회논문집
• /
• pp.711-714
• /
• 2008

The objective of this paper is to know the characteristics of pressure through a simplified typical carburetor used in small engines at the different throttle opening conditions. The carburetor is the device responsible for creating the right air-fuel mixture according to the different engine operating conditions. It is activated by the static or the dynamic pressure. The carburetor dummy is geometrically similar of LPG brush-cutter engine's diaphragm carburetor and is made of acrylic. Suction system gives body to crankcase vacuum using the vacuum pump and throttle opening conditions are controled by transfer device. Carburetor venturi throat and fuel charging tube diameter is each 20mm, 4.1mm. The result of the work presents an unprecedented phenomenon of suction pressure variation inside the carburetor venturi. It is predicted that these unprecedented pressure variation be caused by minor losses; sudden contraction or expansion, open or partially closed and so on.

• Journal of Chest Surgery
• /
• 제25권12호
• /
• pp.1399-1403
• /
• 1992

The evaluation of the effectivess of ongoing cardiopulmonary resucitation efforts is dependent on the commonly used methods, such as the presence of femoral or carotid artery pulsations, arterial blood gas determinations, peripheral arterial pressure and intracardiac pressure monitoring. But recent studies suggest that end-tidal carbon dioxide tension serves as a non-invasive measurement of pulmonary blood flow and therefore cardiac output under constant ventilation. A prospective clinical study was done to determine whether end-tidal carbon dioxide monitoring in open heart surgery under cardiopulmonary bypass could be used as a prognostic indicator of bypass weaning. We monitored end-tidal PCO2 values continuously during cardiopulmonary bypass in 30 patients. "Ohmeda 5210 CO-2 monitor" under infrared absorption method were incorperated into the ventilator circuit by means of a side point adaptor between endotracheal tube and ventilator tubing. 18 patients[Group I ] were res-ucitated from partial bypass followed by aorta cross clamp off and 12 patients[Group II ] from aorta cross clamp off followed by partial bypass. But there was no difference between two groups[p>0.05]. The value of end-tidal carbon dioxide tension during ventricular fibrillation or nearly arrest state was 6.6$\pm$2.9 mmHg, and at the time of spontaneous beating was 19.3$\pm$5.6 mmHg[Mean$\pm$Standard deviation], In conclusion end-tidal carbon dioxide tension monitoring provides clinically useful, continous, noninvasive and supplementary prognostic indicator during cardiopulmonary bypass weaning procedures.rocedures.

• Journal of Chest Surgery
• /
• 제27권3호
• /
• pp.221-225
• /
• 1994

Video-assisted thoracic surgery[VATS] has recently evolved as an alternative to thoracotomy for several thoracic disorders. Between March 1993 and September 1993, 42 patients underwent VATS at Gil General Hospital. They were diagnosed as spontaneous pneumothorax in 34[81.0%], mediastinal mass in 5, congenital lobar emphysema in 1, traumatic hemothorax in 1, and sarcoidosis in 1. For pneumothorax, wedge resection of bullae or blebs was done in 18 patients, wedge resection and limited parietal pleulectomy in 13, and only pleulectomy in 2. And excision for mediastinal mass in 5, hematoma evacuation for chronic hemothorax in 1, biopsies of mediastinal lymph node and lung for confirming sarcoidosis in 1, and lobectomy of left upper lobe for congenital lobar emphysema in the child of 12 years. The period of chest tube drainage and postoperative hospitalization averaged 3.8 days [range, 1 to 11 days] and 5.9 days [range, 2 to 18 days]. Three complications occurred in 3 patients with pneumothorax [7.1%, 2 recurrent pneumothorax and 1 postoperative bleeding], and the conversion to open thoracotomy was done in 1 due to massive air leak. The causes of postoperative air leak were speculated and the techniques for saving expensive Endo-GIA staplers are described in this paper. VATS is safe and offers the benefits of reduced postoperative pain and rapid recovery. Our experience indicates a markedly expanded role for VATS in the diagnosis and treatment of various thoracic diseases.

• 한국측량학회지
• /
• 제34권2호
• /
• pp.111-120
• /
• 2016

Prior knowledge about the SNS (Social Network Services) datasets is often required to conduct valuable analysis using social media data. Understanding the characteristics of the information extracted from SNS datasets leaves much to be desired in many ways. This paper purposes on analyzing the detail of the target social network services, Twitter, Instagram, and YouTube to establish the spatial informatization process to integrate social media information with existing spatial datasets. In this study, valuable information in SNS datasets have been selected and total 12,938 data have been collected in Seoul via Open API. The dataset has been geo-coded and turned into the point form. We also removed the overlapped values of the dataset to conduct spatial integration with the existing building layers. The resultant of this spatial integration process will be utilized in various industries and become a fundamental resource to further studies related to geospatial integration using social media datasets.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• 제35권4호
• /
• pp.271-275
• /
• 2009

The purpose of this report is to describe a treatment method of dentigerous cyst associated with unerupted permanent teeth in mixed dentition patients. In our cases, extraction of infected primary teeth was followed by decompression of the cyst. At the same time, parts of the cystic walls were sent for histopathological examination. Decompression was performed by inserting a rubber tube into the cystic cavity through the extraction socket. The cystic cavity was kept open by means of vigorous use of a syringe by patient. Postoperative panoramic radiograph was taken bimonthly. After $5{\sim}12$ months, the impacted permanent teeth were erupted on the desired position. All cases presented favorable result. By extracting the infected primary teeth, and opening the cyst for continuous drainage, it was possible to achieve spontaneous eruption of the involved permanent teeth into the proper position. In all our cases, there was no sign or symptom of recurrence of the cyst up to postoperative 18 months.