• 대한두개안면성형외과학회지
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• 제21권1호
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• pp.53-57
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• 2020

A mucocele is an epithelium-lined, mucus-filled cavity in the paranasal sinuses. Mucocele may develop due to scarring and obstruction of the sinus ostium caused by midface sinus trauma, such as orbital bone fracture or endoscopic sinus surgery. The authors report two cases of orbital mucocele as complications following midface sinus injury (endoscopic sinus surgery in one case, and orbital fracture repair in the other). In both cases, imaging studies showed a large orbital mucocele accompanied by bony erosion and orbital wall remodeling, compressing the ocular muscle. Using an open approach, the lesion was excised and marsupialized. The symptoms resolved, and the postoperative eyeball position was normal. Orbital mucocele may cause serious complications such as ocular symptoms, orbital cellulitis, osteomyelitis, and the formation of an abscess with the potential to invade the brain. Therefore, surgeons should consider the possibility of mucocele as a late complication of surgery and initiate an immediate work-up and surgical treatment if needed.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2010년 춘계학술대회논문집
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• pp.380-388
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• 2010

A thermal-hydraulic code, named CUPID, has been developed for the analysis of transient two-phase flows in nuclear reactor components. A two-fluid three-field model was used for steam-water two-phase flows. To obtain numerical solutions, the finite volume method was applied over unstructured cell-centered meshes. In steam-water two-phase flows, a phase change, i.e., evaporation of condensation, results in a great change in the flow field because of substantial density difference between liquid and vapor phases. Thus, two-phase flows are very sensitive to the local pressure that determines the phase change. This in turn puts emphasis on the accurate evaluation of local pressure gradient. This paper presents a new numerical scheme to evaluate the pressure gradient at cell centers on unstructured meshes. The results of the new scheme for a simple test function a gravity-driven cavity, and a wall boiling two-phase flow are compared with those of the previous schemes in the cupid code.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2002년도 학술대회지
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• pp.161-164
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• 2002

In the present study, a passive control method, using the porous wall and cavity system, is applied to the shock wave/boundary layer interactions in transonic moist air flow. The two-dimensional, unsteady, compressible Navier-Stokes equations, which are fully coupled with a droplet growth equation, are solved by the third-order MUSCL type TVD finite difference scheme. Baldwind-Lomax turbulence model is employed to close the governing equations. In order to investigate the effectiveness of the present control method, the total pressure losses of the flow and the time-dependent behaviour of shock motions are analyzed in detail. The computed results show that the present passive control method considerably reduces the total pressure losses due to the shock/boundary layer interaction in transonic moist air flow and suppresses the unsteady shock wave motions over the airfoil, as well. It is also found that the location of the porous ventilation significantly influences the control effectiveness.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집B
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• pp.211-216
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• 2001

Flow motion and variation of thermal field around a bubble which attached at the upper cooled solid wall in a $B\dot{e}nard$ convection flow is studied experimentally using thermo-sensitive liquid-crystal tracers and image processing for flow visualization and analysis. The air is injected gradually by $0.1m\ell$ to make the bubble. As the growing of the bubble in a $B\dot{e}nard$ convection flow, the variation of temperature field and surface tension along the bubble, which in turn cause to change the thermal field patterns and the flow direction and patterns. 6 cells flow pattern is transformed into diverse flow pattern. At the large size of a bubble, it's only conduction mechanism under the region of the bubble because of low Ra number 1137, but the convection flow both sides of the bubble leads to another convection flow in the bubble influence area which has been remained stable stagnation.

• 대한기계학회논문집B
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• 제26권5호
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• pp.666-674
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• 2002

A rapid expansion of the moist air or stream through transonic nozzle often leads to not-equilibrium condensation shock, causing a considerable amount of energy loss to the entire flow field. Depending on amount of heat released, condensation shock wave occurs in the nozzle and interacts with the boundary layer flow. In the current study, a passive control technique using a porous wall with a plenum cavity underneath is applied for purpose of alleviation the condensation shock wave in a transonic nozzle. A droplet growth equation is incorporated into two-dimensional wavier-Stokes equation systems. Computations are carried out using a third-order MUSCL type TVD finite-difference scheme with a second-order fractional time step. An experiment using an indraft transonic wind tunnel is made to validate the present computational results. The results obtained show that the magnitude of condensation shock wave is reduced by the current passive control method.

• The Journal of the Acoustical Society of Korea
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• 제28권2E호
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• pp.60-65
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• 2009

The present study aims to investigate the effects of sound diffusers and absorbers on the sound clarity in classrooms. In order to do this, computer simulations were carried out to find the effective area of treatment which could enhance the sound clarity in the room. Acoustic measurements were undertaken in a lecture room with several conditions changing the surface of walls and ceilings with diffusers and absorbers. Diffusion and absorption treatments were applied to the side walls, rear wall and the ceiling of the classroom. SPL, RT, D50, RASTI were measured at 9 measurement points with one sound source and MLS was used as the sound source signal. The results show that higher sound clarity was obtained when diffusers were applied to rear walls and ceiling rather than side walls. Also, it was confirmed that absorption increased sound clarity more effectively with smaller amount in comparison with diffusers. It was also concluded that the effects of sound diffusers and absorbers on the sound clarity could be obtained distinctly at the rear area of the classroom.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2006년도 제5회 박판성형 SYMPOSIUM
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• pp.45-48
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• 2006

Recently, the use of tubular hydroforming technology has seen increased usage and increased consideration for wide range of tubular automotive applications. In manufacturing hydroformed parts, bending and pre-forming operations are often required prior to the hydroforming process. Higher bending quality of bent tubes is crucial for the successful hydroforming operation because most of plastic strains and wall thinning at the extrados of bend area occur in the bending operation. Springback is also observed due to elastic recovery of tube material after bending. Proper correction of springback is required not only to well place the bent tube into a hydroforming die cavity but also to avoid pinching when the upper die is brought down to closing position. Therefore, prediction of springback at early development stage is one of the key factors to produce high quality hydroformed parts. In this study, a variety of bending experiments has been carried out to investigate springback amount under change in bending angle and material boosting. Throughout the experimental approach, springback characteristics of bent tubes are quantified according to the change in various bending parameters, and a mathematical model to predict correction amount of springback to a given bend angle is found.

• Journal of Chest Surgery
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• 제25권6호
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• pp.630-636
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• 1992

From August 1990 through December 1991, 14 patients[all males] underwent int-rathoracic muscle transposition of extrathoracic skeletal muscles to treat empyemas, 6 patients had tuberculous empyemas, 4 had chronic empyemas of unknown etiology, 3 had pos-tpneumonectomy empyemas, and 1 had postlobectomy empyema. 9 patients had associated bronchopleural fistulas, Their ages ranged from 22 to 67 years, with mean age of 45.1$\pm$17. 6[$\pm$S.D] years. The serratus anterior was transposed in 13 patients, the latissimus dorsi in 12. In 11 patients, both the serratus anterior and the latissimus dorsi were transposed. The omental flap also transposed in 3 patients. To reduce the dead space in the thoracic cavity, thr-oacoplasty was also carried out in 10 patients. The number of the partially resected ribs was 3.0$\pm$0.8[$\pm$S.D.]. All operations were single stage procedures, and all wounds were closed primarily, with no permanent tubes or chest wall openings. There was no hospital mortality, and so no subsequent operation has been required. Follow-up of the patients ranged from 5 to 16 months with a mean of 9.2$\pm$3.1[$\pm$S.D] months, All the patints had no further signs or symptoms of the original infection after discharge. We conclude that intrathoracic transposition of extrathoracic skeletal muscle is an excellent method of treatment for persistent, life-threatening intrathoracic infections.

• Journal of Chest Surgery
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• 제43권3호
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• pp.328-331
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• 2010

흉막외혈종은 혈흉과 달리 출혈된 혈액이 가슴막공간에 고이지 않고 벽측가슴막과 가슴속근막(endothoracic fascia) 사이에 고이는 질환이다. 이 질환은 흉벽혈관 손상후 벽측가슴막이 손상되지 않아서 혈액이 가슴막 공간으로 나오지 못하여 발생한다. 컴퓨터단층촬영에서 흉벽의 벽측가슴막과 가슴속근막 사이에 있는 지방층이 가슴막 밖에 위치하는 가슴막밖 지방 징후로 진단할 수 있다. 저자들은 외상후 흉막외혈종을 진단하고 비디오흉강경수술로 성공적으로 치료하였기에 문헌고찰과 함께 보고하는 바이다.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2003년도 종합학술발표회 논문집 Vol.13 No.1
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• pp.288-293
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• 2003

본 논문에서는 IMT2000 중계기에 사용될 수 있는 대역통과 필터를 도파관 구조를 갖는 콤라인 형태의 공진기를 사용하여 설계하였다. 공진기 사이의 결합은 필터의 크기를 작게하기 위하여 공진기 사이의 벽에 슬롯을 이용하여 구현하였다. 5개의 공진기는 동일한 구조를 가지고 있으며 입 출력부분은 최소 임피던스가 되도록 최적화 시켰다. 대역통과 필터 특성은 0.2dB 리플을 갖는 체비세프 함수를 이용하였으며 시뮬레이션 툴을 이용하여 해석한 결과 설계 조건을 만족하였다.