• 한국수소및신에너지학회논문집
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• 제28권3호
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• pp.308-314
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• 2017

Jet pump in automotive fuel tank module is used to deliver fuel to fuel pump so that the pump is operated without aeration in suction side. In this study, three dimensional simulation model of jet pump is developed to understand performance variation over design parameters. Performance of jet pump is also investigated experimentally in terms of operating pressures. The experimental data is used to verify the three dimensional simulation model of jet pump. Verification results show that the three dimensional simulation model of jet pump is about 1% error with experiment. The simulations are conducted in terms of throat ratio and primary flow induction angle. As the throat ratio is increased, the flux ratio is trade-off at 3 times of throat diameter. On the other hand, as primary flow induction angle is increased, vapor pressure inside the nozzle is decreased. In summary, the results show that liquid jet pump has to be optimized over design parameters. Additionally, high velocity of induced flow is able to evolve cavitation phenomena inside the jet pump.

• 대한기계학회논문집B
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• 제24권8호
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• pp.1128-1138
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• 2000

Pumping action in ejector systems is generally achieved through the mixing of a high-velocity and high-energy stream with a lower-velocity and lower-energy stream within a duct. The design and performance evaluation of the ejector systems has developed as a combination of scale-model experiments, empiricism and theoretical analyses applicable only to very simplified configurations, because of the generic complexity of the flow phenomena. In order to predict the detailed performance characteristics of such systems, the flow phenomena throughout the operating regimes of the ejector system should be fully understood. This paper presents the computational results for the two-dimensional supersonic ejector system with a second throat. The numerical simulations are based on a fully implicit finite volume scheme of the compressible Reynolds-averaged Navier-Stokes equation in a domain that extends from the stagnation chamber to the diffuser exit. For a wide range of the operating pressure ratio the flow field inside the ejector system is investigated in detail. The results show that the supersonic ejector systems have an optimal throat area for the operating pressure ratio to be minimized.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.526-531
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• 2003

A cone cylinder is used to obtain variable operation conditions of a sonic ejector-diffuser system. The cone cylinder is movable to change the ejector area ratio, thus obtaining variable mass flow rates. The present study investigates the effects of ejector throat area ratio and operating pressure ratio on the entrainment of secondary stream. The numerical simulations are based on a fully implicit finite volume scheme of the compressible, Reynolds-Averaged, Navier-Stokes equations. The ejector throat area is varied between 3.94 and 8.05, and the operating pressure ratio is changed from 3.0 to 9.0. The results show that the entrainment ratio and mass flux ratio become more dependent on the ejector throat area ratio, when the pressure operating ratio is low. The total pressure losses produced in the present ejector system increase with the operating pressure ratio and the ejector area ratio, but for a given operating pressure ratio, the losses are not significantly dependent on the ejector area ratio when it is larger than about 5.0.

• 한국항공우주학회지
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• 제37권12호
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• pp.1245-1251
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• 2009

고온/고압, 장시간 연소조건에서 비삭마에 가까운 삭마 특성을 갖는 초소형 목삽입재 선정을 위한 연구를 수행하였다. 평가 소재로서 C/SiC, CIT, W/$Y_2O_3$를 선정하였으며, 연소시간 20초의 내열성능평가모타로 시험하였다. 시험 결과 W/$Y_2O_3$가 가장 우수하였으나, 균열이 발생하였다. 본 연구를 통하여 각 소재들의 열반응 특성 및 내열 성능을 이해할 수 있었으며, W/$Y_2O_3$의 적용가능성을 확인하였다.

• Pediatric Infection and Vaccine
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• 제2권2호
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• pp.180-185
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• 1995

1. Purpose The accurate diagnosis and proper treatment of group A streptococcus should be emphasized concerning about possible development of late sequelae, such as acute rheumatic fever and acute glomerulonephritis. We would like to know the recover rate of beta-hemolytic streptococci by throat swab culture at the in-patient 2. Methods The throat swab cultures and filled up flow-sheets were undertaken on 619 children who had admitted to hospital, KyungHee university hospital from may 1994 to april 1995 prospectively. At the same time on admission, throat culture was performed. 3. Results The highest recover rate of BHS(Beta-Hemolytic Streptococci)and GAS(Group A Streptococci) were seen in above 10 years old, as 9.1% and 1.9%. BHS were obtained in 39 cases(6.3%) among 619 children while GAS was obtained in 3 cases (0.4%). Among 39 specimens of BHS, 33 specimens were classified as non-grouping streptococcus. 4. Conclusion The poor recovery rate of GAS inpatient compared with normal carrier rate is likely due to possible antibiotic abuse, errors in processing samples, and epidemiologic factors such as seasons and geographic areas. It is necessary to evaluate the clinical significance of non-A,B,C,G streptococcal infections and carriers.

• Journal of Korean Biological Nursing Science
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• 제22권3호
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• pp.204-212
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• 2020

Purpose: The purpose of this study was to examine the effect of nebulizer therapy with normal saline on thirst and sore throat among postoperative patients. Methods: A quasi-experimental nonequivalent control group, pretest-posttest design was used with 50 participants. The experimental group received nebulizer therapy with normal saline every two hours for 10 minutes three times and wet gauze (n= 25), and the control group received only wet gauze (n= 25). Data were collected using the Numeral Rating Scale for Thirst and Sore Throat. Measurements were calculated before applying nebulizer therapy and total five times for 12 hours after treatment. Data were analyzed using the repeated measured ANOVA. Results: Thirst for the experimental group using the nebulizer therapy with normal saline improved more than for the control group (F= 3.06, p= .043). Sore throat was not significantly different between the two groups (F= 0.63, p= .565). Conclusion: Study results indicate that using nebulizer therapy with normal saline can reduced thirst for postoperative patients. So nurses can apply nebulizer therapy with normal saline to reduce thirst and to improve comfort for postoperative patients.

• 재활간호학회지
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• 제14권2호
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• pp.136-144
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• 2011

Purpose: A purpose of this study was to identify the effects of cold water gargling on thirst, oral cavity condition and sore throat in orthopedics surgery patients who underwent general anesthesia. Methods: Pretest-posttest non-synchronized design with a nonequivalent control group was used. A total of 52 participants were conveniently selected and assigned to each group. The experimental group gargled hourly with cold water for 8 hours after operation. The control group received wet gauze as needed. We compared the thirst, oral cavity condition and sore throat at 0, 2, 4 and 8 hours after operation. Results: The score of thirst and oral cavity condition was lower in the experimental group than in the control group. However, there was no significant differences in the levels of sore throat between the experimental and control group. Conclusion: These findings suggest that cold water gargling can be a useful nursing intervention for alleviating thirst and improving oral condition for patients with orthopedic surgery after general anesthesia.

• 대한후두음성언어의학회지
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• 제31권1호
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• pp.39-44
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• 2020

We present four cases of aberrant carotid arteries manifesting as pharyngeal masses with throat discomfort. The symptoms of this anomaly are very similar to those of laryngopharyngeal reflux or globus pharyngeus. The identification of this anomalous artery is essential for the head and neck surgeon because the anomaly frequently manifests as a symptomatic pulsatile mass in the pharynx. All patients complained of foreign body sensation in the throat and showed protrusion of the posterolateral pharyngeal wall anteromedially. CT scans demonstrated that there were two cases involving the right common carotid artery (CCA) and two cases involving both CCAs in the retropharyngeal space. As conclusion, the aberrant course of the artery can occur on both sides of CCAs, and it can manifest as a pharyngeal mass. When the patients complain of foreign body sensation in the throat without any other abnormal findings in the pharynx, we should consider the possibility that it may be due to the aberrant course of the CCA and its bifurcations in the retropharyngeal space.

• 대한기관식도과학회지
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• 제3권1호
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• pp.79-83
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• 1997

The term laryngopharyngeal reflux (LPR) refers to the backflow of food or stomach acid back up into the larynx (the voice box) or the pharynx (the throat). Esophagopharyngeal reflux is suggested as an etiologic factor in laryngeal disease. To examine a possible esophageal basis for laryngopharyngeal symptoms, we studied 48 patients with persistent laryngopharyngeal symptoms, and 12 relative control subjects. Patients were evaluated for cervical symptoms by questionnaire and underwent gastrofiberoscopy, fiberoptic laryngoscopy, esophageal manometry and 24-hour ambulatory double-probe pH monitoring. We found LPR in fourteen out of 48 patients with cervical symptoms (29%). The LPR group consisted of nine men and five women. The symptoms that LPR patients complained were throat lump sensation, hoareness, sore throat, throat clearing, chronic coughing and dysphagia in order of frequency, and they were not different significantly from non-LPR patients. The laryngoscopic findings in LPR patients were posterior erythema, laryngeal edema and diffuse erythema, and there was also no significant difference between LPR group and non-LPR group. There was statistically significant correlation between LPR and gastroesophageal reflux (GER). We concluded that there is no pathognomonic symptoms or laryngoscopic findings in diagnosis of LPR, and 24-hour ambulatory double-probe pH monitoring is an essential diagnostic tool in LPR.

• 한국추진공학회지
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• 제23권1호
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• pp.24-32
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• 2019

유체 추력벡터 제어에서 이중목 노즐 개념의 이용 가능성을 조사하기 위하여, 초음속 노즐에서 수치해석을 수행하였다. 수치해석 검증에서 SST $k-{\omega}$ 난류모델을 사용하여 실험결과를 잘 구현하였다. 광범위한 노즐 압력비와 분사 압력비에서 편향각도, 시스템의 전체 추력비 및 추력 효율을 조사하였다. 본 연구에서 이중목 노즐의 추력벡터제어 시스템의 성능 변화는 2차원 계산영역에서 명확하게 설명되었다. 본 연구에서 얻어진 결과들은 유체추력벡터제어 분야에 중요한 기초자료를 제공할 것이다.