• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2003년도 The Fifth Asian Computational Fluid Dynamics Conference
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• pp.294-298
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• 2003

The complex, unsteady, self-sustained pressure oscillations induced by supersonic flow past a rectangular cavity is investigated using numerical simulations. The present numerical study is performed using a parallel, multiblock solver for the two-dimensional, compressible Navier­Stokes equations. Open cavities with length-to-depth (L / D) ratio in the range 0.5 - 3.3 are considered. This paper sheds light on the cavity physics, cavity oscillatory mechanism, and the organisation of vortical structures inside the cavity. The vortex shedding phenomenon, the shear layer impingement event at the aft wall and the movement of the acoustic/compression wave within the cavity are well predicted. The vortical structures· and the source of the acoustic disturbances are found to be located near the aft wall of the cavity. With the increase in the cavity length, strong recompression of the flow near the aft wall leading to a sudden jump in the cavity form drag is observed. The estimated cavity tones are in good agreement with the available semi­empirical relation. Multiple peaks are noticed in deep and long cavities. For the present free­stream Mach number 1.71, it is observed that around L/D=2.0, the cavity oscillatory mechanism changes from the transverse to longitudinal oscillatory mode. The effects of this transition on various fluid dynamics and acoustic properties are also discussed.

• 대한수의학회지
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• 제31권4호
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• pp.457-469
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• 1991

Clinical and bacteriological observations on infectious atrophic rhinitis of swine were conducted in order to obtain some basic information for the clinical and immnnological control of the disease prevailing in the republic. Samples were collected from nasal cavities of 135 4~12 week old pigs from 12 herds and from turbinates of 199 slaughtering pigs from 14 swine herds to investigate the prevalence of Bordetella bronchiseptica and/or Pasteurella multocida in the nasal cavities of the pigs. On the examination of nasal swabs by cultural techniques and of gross lesion of snouts of slaughtering pigs, all the swine herds investigated were found to be affected by atrophic rhinitis and a total of 84 B bronchiseptica and 139 P multocida cultures were isolated from the nasal cavities of the pigs. Of the 199 slaughtering pigs, some 48% revealed gross pathological lesion typical of atrophic rhinitis and the prevalence of B bronchiseptica and P multocida were 27.6% and 46.7%, respectively. Biochemical properties, antimicrobial susceptibilities, serological characteristics and toxigenicity of the isolates of B bronchiseptica and P multocida were investigated.

• 한국터널지하공간학회 논문집
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• 제4권2호
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• pp.113-121
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• 2002

석회암 지역에서 불규칙하게 발견되고 있는 공동의 규모와 위치를 표준화하여 터널에 미치는 영향을 수치해석적으로 접근하여 영향권을 설정하였다. 공동의 불규칙한 모서리 부분의 응력집중 문제는 해석의 한계때문에 타원형으로 모델링 되었다. 공동의 위치가 터널의 천단부와 하부 모서리에 있는 경우 가장 큰 영향을 나타났다. 굴착되는 터널크기의 공동이 1D (터널직경)정도 이격되어 있으면 안정성에는 큰 영향이 없는 것으로 나타났다. 터널과 공동의 이격거리가 0.25D (터널직경) 이내의 경우에는 변위 및 지보재에 미치는 영향이 큰 것으로 나타났다.

• Restorative Dentistry and Endodontics
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• 제45권1호
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• pp.5.1-5.8
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• 2020

Objectives: The obturation quality of MTA, Biodentine, Total Fill BC root canal sealer (RCS), and warm gutta-percha (WGP) in teeth with simulated internal root resorption (IRR) was evaluated by using micro-computed tomography. Materials and Methods: Standardized IRR cavities were created using 40 extracted maxillary central incisor teeth and randomly assigned into 4 groups (n = 10). IRR cavities were filled with MTA, Biodentine, Total Fill BC RCS (bulk-fill form) and WGP + Total Fill BC RCS. Percentage of voids between resorptive cavity walls and obturation material (external void), and inside the filling materials (internal voids) were measured. Results: Total Fill BC sealer in the bulk-fill form presented significantly highest values of external and internal void percentages (p < 0.05). Biodentine showed a significantly lowest external void percentage (p < 0.05). WGP + Total Fill BC RCS presented significantly lower values of internal void percentages than all groups (p < 0.05), except Biodentine (p > 0.05). Conclusion: None of the filling materials were created void-free obturation in resorption cavities. Biodentine may favor its application in teeth with IRR over Angelus MTA and bulkfill form of Total Fill BC.

• Restorative Dentistry and Endodontics
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• 제15권2호
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• pp.34-45
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• 1990

The purpose of this study was to evaluate the pulpal responses of S. mutans (6715, serotype A) in relation to the remaining dentin thickness. The material was consisted of 72 teeth from 6 dogs. Cl. V cavities were prepared into 2 different thickness (0.5mm, 1.0mm) of remaining dentin. In the control groups, the cavities were filled with filter paper of broth, tin foil, and IRM$^{(R)}$ cement. In the experimental groups, the cavities were filled with filter paper of S. mutans, filter paper of broth, tin foil, and IRM$^{(R)}$ cement. The intervals of observation period were 1 week, 3 weeks, and 8 weeks respectively after the experiment. The specimens were fixed with 10% formalin and decalcified in 5% nitric acid. All specimens were stained with Hematoxylin-Eosin and examined histopathologically under the microscope. The results were as follows. 1. The changes and congestion of odontoblastic layers were more frequent and lasting in the control group of 0.5mm than in that of 1.0mm remaining dentin thickness. 2. There was no characteristic difference between the control group of 1.0mm and the experimental group of 1.0mm in all pulp responses. 3. Acute and chronic inflammatory cells were seen in the experimental group of 0.5mm, but not seen in the control group of 0.5mm.

• 한국생산제조학회지
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• 제24권6호
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• pp.682-686
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• 2015

The objective of this study is to validate the performance of the current $k-{\epsilon}$ turbulence model for a single-phase turbulent natural convection, which has been considered an important phenomenon in nuclear safety. As a result, the natural convection problems in the 2D and 3D cavities previously studied are calculated by using the ANSYS Fluent software. The present results show that the current $k-{\epsilon}$ turbulent model accounting for the buoyancy effect is in good agreement with the previous results for the natural convection problems in the 2D and 3D cavities although some improvements should be required to get better prediction.

• 한국구조물진단유지관리공학회 논문집
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• 제6권3호
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• pp.177-184
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• 2002

The most tunnel damage such as cracks or leakage which exist in tunnel lining commonly, is caused by the cavities where exist behind the tunnel lining, through the tunnel safety inspections. These cavities were analysed to affect a stability of a running-tunnel seriously. This study is on the development of the controlled low-strength and flowable filling material which is able to apply to the cavity behind the tunnel lining. The major materials of backfilling developed are a crushed sand and a stone-dust which exists as a cake-state and is a by-product obtained in the producting process of aggregate. It is conformed with the design standard to the physical characteristics of backfilling. The backfilling material developed is designed to reduce the fair amount of cement. According to the designed compound ratio, it is carried out the laboratory tests such as a compressive strength and a chemical analyses and is applied to dilapidated old tunnel for an application assessment.

• Journal of electromagnetic engineering and science
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• 제4권1호
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• pp.30-36
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• 2004

We determined equivalent circuit parameters of a 1.5 cell S-band RF gun cavity from the resonant characteristics of its decoupled cavities(half cell and full cell) using the code SUPERFISH. Equivalent circuit parameters of the 1.5 cell RF gun cavity resonated in the 0-mode were obtained easily from the circuit parameters of each decoupled cavities. In order to obtain equivalent circuit parameters for the $\pi$ -mode cavity, we calculated the differences of the resonant frequencies and the equivalent resistances between the 0- and $\pi$ -modes with slight variations of the radius and thickness of the coupling iris. From those differences, we obtained R/Q value and equivalent resistance of the $\pi$ -mode, which are directly related to the equivalent circuit parameters of the coupled cavity. Using calculated R/Q value, we can express equivalent inductance, capacitance and resistances of the RF gun cavity resonated in the $\pi$ -mode, which can be useful for analyzing coupled cavities in a steady state.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2008년도 공동학술대회
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• pp.167-172
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• 2008

경북 문경군 가은읍 가은역 일대 석회암 분포 지역에서 지하 공동의 위치 및 발달 양상을 파악하기 위하여 고정밀 중력탐사를 하였다. 측점 간격은 4m로 하여 모두 약 1,100 측점에서 중력을 측정하였다. 잔여 부게 이상도에서 가장 낮은 중력 이상대를 지나는 3개의 측선에 대하여 MS(minimum support) 역산으로 밀도 분포 단면을 작성하였다. 또한, growing body 역산을 이용하여 3차원 밀도 분포 영상을 구하였다. 2차원과 3차원 밀도 분포도는 공동이 발달한 지역을 잘 가리키고 있으며, 석회암이 지하수에 부분적으로 용해되어 복잡한 형태의 공동 시스템을 구성하고 있고 부분적으로는 상당히 얕은 곳까지 발달해 있을 것으로 해석된다.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2007년도 공동학술대회 논문집
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• pp.241-244
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• 2007

Cement-grouts are injected into limestone cavities beneath the road in the project area, in order to improve strength and reduce permeability; the extent to which grout has penetrated in cavities need to be monitored in order to determined effectiveness of cement-grout. Geophysical approaches, offer great potential for monitoring the grout injection process in a fast and cost-effective way as well as showing whether the grout has successfully achieved the target. This paper presents the ability of surface electrical resistivity to investigate the verification of the grout placement. In order to image the cement-grout, time-lapse surface electrical resistivity surveys were conducted to compare electrical resistivity images before and after injection. Cement-grout was imaged as anomalies exhibiting low resistivity than the surrounding rocks. In accordance with field monitoring, laboratory study was also designed to monitor the resistivity changes of cement-grout specimens with time-lapse. Time-lapse laboratory measurements indicated that electrical methods are good tool to identify the grouted zone. Pre-and post grouting electrical images showed significant changes in subsurface resistivity at grouted zone. The study showed that electrical resistivity imaging technology can be a useful tool for detecting and evaluating changes in subsurface resistivity due to the injection of the grout.