• International Journal of Fluid Machinery and Systems
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• 제8권2호
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• pp.94-101
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• 2015

To investigate the influence of blade profiles on cavitation behavior in impeller of centrifugal pump, a centrifugal pump with five different blade profiles impellers are studied numerically. The impellers with five different blade profiles (single arc, double arcs, triple arcs, logarithmic spiral and linear-variable angle spiral) were designed by the in-house hydraulic design code using geometric parameters of IS 150-125-125 centrifugal pump. The experiments of the centrifugal pump have been conducted to verify numerical simulation model. The numerical results show that the blade profile lines has a weak effect on cavitation inception near blade inlet edge position, however it has the key effect on the development of sheet cavitation in impeller, and also influences the distribution of sheet cavitation in impeller channels. A slight changing of blade setting angle will induce significant difference of cavitation in impeller. The sharp changing of impeller blade setting angle causes obvious cavitation region separation near the impeller inlet close to blade suction surface and much more flow loss. The centrifugal pump with blade profile of setting angle gently changing (logarithmic spiral) has the super cavitation performance, which means smaller critical cavitation number and lower vapor cavity volume fraction at the same conditions.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2002년도 학술대회지
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• pp.155-158
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• 2002

In general, TVC(Thermal Vapor Compressor) is used to boost/compress a low pressure vapor to a higher pressure for further utilization. The one-dimensional method is simple and reasonably accurate, but cannot realize the detail as like the back flow and recirculation in the mixing chamber, viscous shear effect, and etc. In this study, the axisymmetric How simulations have been performed to reveal the detailed flow characteristics for the various ejector shapes. The Navier-Stokes and energy equations are solved together with the continuity equation In the compressible flow fields. The standard $k-{\epsilon}$ model is selected for the turbulence modeling. The commercial computational fluid dynamic code FLUENT software is used for the simulation. The results contain the entrainment ratio under the various motive, suction and discharge pressure conditions. The numerical results are compared with the experimental data, and the comparison shows the good agreement. The three different flow regimes (double chocking, single chocking and back flow) have been clearly distinguished according to each boundary pressure values. Also the effects of the various shape variables (nozzle position, nozzle outlet diameter, mixing tube diameter, mixing tube converging angle, and etc.) are quantitatively discussed.

• 대한기계학회논문집A
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• 제24권8호
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• pp.1931-1939
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• 2000

Operating excitation forces of the linear vibratory system are normally determined by direct measurement techniques using load cells, strain gauges, etc. But, hydraulic forces of the rotating turbomachinery such as centrifugal pumps are exerted on an impeller due to asymmety of the flow by the interaction between pump impeller and volute. So, investigations of wide range of hydraulic designs and geometric deviations are difficult by direct method. This paper presents a hybrid approach for fourier transformed operational excitation forces, which uses pseudo-inverse matrix of the transfer matrix for the system and the measured vibrational data with standard installed pump. The determination of the transfer function matrix is based on a linear rotor/stationary system and steady state harmonic response in finite element analysis. And, vibrational data is collected in both vertical and horizontal directions at inboard and outboard bearing housings. The results of the process may be enhanced by making acceleration measurements at many more locations than there are forces to be determined.

• The Korean Journal of Pain
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• 제9권1호
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• pp.210-214
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• 1996

Thoracic sympathetic ganglion block(TSGB) with alcohol is a traditional method for treating a variety of disease at pain clinics. But it is a difficult block to perform requiring both skill and experience. Therefore, we performed a thoracic endoscopic cauterization to evaluate the efficacy of this method. A patient suffering sever forearm and hand pain due to radius fracture of the right arm, one and half years earlier, was referred to several different orthopaedic department of various hospitals with continued aggravated symptoms. He was then admitted to our hospital's orthopaedic department. Our diagnosis, confirmed by thermography, revealed reflex sympathetic dystrophy. Patients was therefore referred to the pain clinic where treatment consisted of endoscopic thoracic sympathetic cauterization under general anesthesia. Patient was intubated with Robertashow 37 Fr. double lumen tube left sided. Left lateral and slight head up position was applied to make lesion side up. Incisions were made to penetrate trocas 5 mm diamether on 4 th intercostal space along mid axillary line and midclavicular line. Negative pressure suction on ipsilateral lung and CO2 insufflation under 10 mmHg was applied to reduce lung size. Cauterization on thoracic sympathetic chain at T3 level was done under endoscoic guide. 24 Fr. chest tube was inserted. Patient's symptoms cleared and he was satisfied with the results of this treatment.

• 한국산학기술학회논문지
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• 제19권1호
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• pp.121-126
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• 2018

중환자실에 입원한 환자들의 구강위생은 매우 중요한 문제이다. 중환자들은 기본적으로 면역이 저하된 환자들로 각종 병원성 세균들에 의한 감염의 기회가 높기 때문이다. 구강문제는 감염의 1차 방어선인 구강이 감염의 우선적인 부위로 작용될 뿐 아니라 전신감염을 초래하기도 한다. 본 연구에서는 중증환자의 구강청소를 용이하게 하는 마우스 피스 형태의 새로운 진공 구강 세정기 설계에 관한 연구를 수행하였다. 이중 구조 방식의 세정기와 표준 치아 모델로써 3D CAD 모델링 및 유동해석 모델을 수립하고 압력 및 유동특성을 분석하였다. 세정기 내부의 압력은 거의 일정한 분포를 보였으나, 속력분포의 경우 치아 안쪽과 바깥쪽에서 큰 차이를 보였다. 치아 안쪽에서도 가운데 부분의 속도가 가장 높고 가운데에서 멀어질수록 속력이 감소하는 특성을 보였다. 세정기의 흡입관과 배출관을 바꾸어 해석한 결과 치아 바깥쪽 가운데 부분의 속도가 가장 높게 나타났다. 세정기의 효과를 높이기 위해서 흡입-배출을 교대로 바꾸는 교번식을 제안하고, 어금니 부위의 속력을 높이는 설계 보완이 요구된다.

• International Journal of Fluid Machinery and Systems
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• 제4권3호
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• pp.334-340
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• 2011

Turbo-pumps have weak points, such as the pumping operation is unstable on the positive slope of the head curve and/or the cavitation occurs at the low suction head. To improve simultaneously both weak points, the first author invented the unique pumping unit composed of the tandem impellers and the peculiar motor with the double rotational armatures. The front and the rear impellers are driven by the inner and the outer armatures of the motor, respectively. Both impeller speeds are automatically and smartly adjusted in response to the pumping discharge, while the rotational torques between both impellers/armatures are counter-balanced. Such speeds contribute to suppress successfully not only the unstable operation at the low discharge but also the cavitation at the high discharge, as verified with the axial flow type pumping unit in the previous paper. Continuously, this paper investigates experimentally the effects of the tandem impeller profiles on the pump performances and the rotational speeds against the discharge, using the impellers whose loads are low and/or high at the normal discharge. The worthy remarks are that (a) the unstable operation is suppressed as expected and the shut off power is scarcely large in the smart control, (b) the blade profile contributes to determine the discharge giving the maximum/minimum rotational speed where the reverse flow may incipiently appears at the front impeller inlet, (c) the tandem impeller profiles scarcely affect the rotational speeds, while the loads of the front and the rear impellers are same, but (d) the impeller with the low load must run faster and the impeller with the high load must run slower at the same discharge to take the same rotational torque, and (e) the reverse flow at the inlet and the swirling velocity component at the outlet of the front impeller with the high load require making the rotational speed of the rear impeller with low load fairly faster at the lower discharge.

• Journal of Korean Neurosurgical Society
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• 제29권8호
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• pp.1113-1120
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• 2000

Objectives : Despite advance in the surgical treatment of the intracranial aneurysm, we have to be surgical complication. The aim of this report is to evaluate the complication and its management in intracranial aneurysm operation. Methods : We reviewed our exprience with interesting cases of surgical complication of intracranial aneurysm : 1) rebleeding, 2) intra-operative premature rupture, 3) missed aneurysm in angiography, 4) vasospasm. Results : The risk of rebleeding was not related to the patients' initial comdition, but all other intracranial complications occurred significantly more often in patients graded poor compared with patients in good clinical condition. Rebleeding before early surgery remains as major cause of unfavorable outcome. The causes of intraoperative premature ruptures were as follows : 1) dural opening and arachnoid opening(8.3%), 2) hematoma removal(12.5%), 3) brain retraction(16.7%) 4) aneurysm dissection(62.5%). The double suction technique and primary hemostasis using a small piece of cotton or temporary clip resulted in good outcome even in cases with premature rupture. The incidence of missed aneurysm in angiography occurred in 10%. The causes were as thrombosed aneurysm, vasospasm on feeder artery. The most common missed aneurysm is also the most common aneurysm(anterior communicating artery aneurysm). The repeated angiography were documented in missed aneurysm. Balloon angioplasty is superior topapaverine for treatment of proximal vessel vasospasm by viture of a more sustained effect on the vessel. Papaverine can be useful as an adjunct to ballon angioplasty and also for the treatment of distal vessels that are not accessible for ballon angioplasty. Conclusion : The minimization of the complications and active treatment can reduced the mortality and morbidity of ruptured aneurysm patients.

• 한국추진공학회지
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• 제14권6호
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• pp.60-68
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• 2010

본 연구에서는 팁 형상이 가스터빈 블레이드의 팁 열전달에 미치는 영향을 알아보기 위하여 선형 캐스케이드의 블레이드에 설치된 평면 팁, 스퀼러 팁, Groove 팁들에 대하여 열전달 계수가 측정되었다. 블레이드 팁에서의 열전달 계수는 색상검출방식에 기반을 둔 천이액정법을 이용하여 측정되었으며 각각의 팁 형상에 대하여 팁 간극은 블레이드 스팬의 1.5%와 2.3% 두 조건에서 실험을 수행하였다. 캐스케이드 출구 속도와 블레이드 코드길이에 기초를 둔 Reynolds 수는 $2.48{\times}10^5$ 이다. Groove 팁 표면에서의 열전달 계수는 평면 팁보다 낮게 측정되었으며, 특히 흡입면을 따라 경사진 홈이 파인 팁에서는 스퀼러 팁보다 낮은 열전달 계수가 측정되었다.

• Clinical and Experimental Pediatrics
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• 제45권2호
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• pp.261-266
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• 2002

저자들은 출생 후 호흡기 증상이 지속되어 오던 여아가 respiratory syncytial virus와 b형 헤모필루스 인플루엔자균에 의한 하기도 감염에 이환되면서 생후 4개월에 혈관륜으로 진단된 1예를 보고하는 바이다. 환아는 출생 후 협착음과 천명음 등의 잦은 호흡기 증상을 보였고, 3개월에 호흡 곤란을 주소로 입원하였으며 respiratory syncytial virus에 의한 세기관지염으로 치료받고 호전되었다. 퇴원 후 증상이 다시 악화되어 재입원 하였으며 b형 헤모필루스 인플루엔자균에 의한 기관염 및 폐렴이 확인되었고, 치료를 위해 기관내 튜브에 도관 삽입을 시도하였을 때 하부 기도에서 저항감이 감지되어 기도 부위의 해부학적 기형을 의심하게 되었다. 3차원 흉부 단층 촬영에서 이중 대동맥궁으로 인한 혈관륜이 확인되었고, 교정 수술을 시행한 후 좋은 경과를 보이고 있다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2010년도 제34회 춘계학술대회논문집
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• pp.311-318
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• 2010

본 연구에서는 팁 형상이 가스터빈 블레이드의 팁 열전달에 미치는 영향을 알아보기 위하여 선형 캐스케이드의 블레이드에 설치된 평면 팁, 스퀼러 팁, Groove 팁들에 대하여 열전달 계수가 측정되었다. 블레이드 팁에서의 열전달 계수는 색상검출방식에 기반을 둔 천이액정법을 이용하여 측정되었으며 각각의 팁 형상에 대하여 팁 간극은 블레이드 스팬의 1.5%와 2.3%로 변경 하에 실험을 수행하였다. 캐스케이드 출구 속도와 블레이드 코드길이에 기초를 둔 Reynolds 수는 $2.48{\times}10^5$ 이다. Groove 팁 표면에서의 열전달 계수는 평면 팁보다 낮게 측정되었으며, 특히 흡입면을 따라 경사진 홈이 파인 팁에서는 스퀼러 팁보다 낮은 열전달 계수가 측정되었다.