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곽현덕,전성민,김진한 한국유체기계학회 2007 한국유체기계학회 논문집 Vol.10 No.1
A mechanical face seal has been tested in Korea Aerospace Research Institute for turbopump applications. In this paper the acceptance test results of the mechanical face seal are described. By means of simulating a practical operating environment, the performance against leakage of mechanical face seal is monitored. In addition the carbon wear is measured to estimate the life of a mechanical face seal. The test results show the acceptable leakage performance and resonable wear tendency as well. Lastly the repeated test had been carried out to guarantee the endurance performance of mechanical face seal based on the turbopump life.* 한국항공우주연구원 터보펌프팀
역스월 유로 입력을 가지는 밸런스 슬리브를 적용한 고압 다단 펌프의 진동 특성
곽현덕,이용복,김창호,이봉주 한국소음진동공학회 2002 한국소음진동공학회 논문집 Vol.12 No.8
As the tangential flow inside the clearance of tribo elements such as bearings and seals is increased as the shaft speed increases, the system stability will be decreased due to the increment of the instability parameter. To reduce the tangential flow inside the clearance of the balance sleeve, anti-swirl injection mechanism is applied. The balance sleeve is used in resisting the axial force induced by impeller in high pressure multi-stage pump. In this paper, total three cases are experimentally investigated; original balance sleeve, anti-swirl injection balance sleeve with 0 axial degree and anti-swirl injection balance sleeve with 30 axial degree. Experiments are focused in the comparison of vibration level and leakage flow rate. The results clearly shows that the anti-swirl injection balance sleeve with 0 axial degree improves the vibration characteristics. However, the anti-swirl injection balance sleeve with 30 degree aggravates the vibration characteristics. In the standpoint of leakage performance, both anti-swirl injection balance sleeves show the better result than the original balance sleeve.
유리체강내 트리암시놀론 주입술로 호전된 임신 중 발생한 보그트-고야나기-하라다 병 1예
곽현덕,임성협,김현웅,윤일한,이호영,Hyun Duck Kwak,MD,Sung Hyup Lim,MD,Hyung Woong Kim,MD,PhD,Il Han Yun,MD,PhD,Ho Young Lee,MD 대한안과학회 2013 대한안과학회지 Vol.54 No.10
Purpose: To report a case of Vogt-Koyanagi-Harada (VKH) disease in a pregnant patient treated with intravitreal triamcinolone injection. Case summary: A 21-year-old female in the 19th week of gestation presented with bilateral blurring of vision associated with mild headache and tinnitus. Her initial best corrected visual acuity was 0.15 in the right eye and 0.3 in the left eye. Multiple serous retinal detachment and anterior chamber inflammation were observed, and VKH disease was diagnosed. Because of her pregnancy, the patient did not want high-dose systemic prednisolone therapy which may cause an abortion or low birth weight infant when used in a pregnant patient. Therefore, an intravitreal triamcinolone (4 mg/0.1 ml) injection was given in the right eye and topical steroid eye drops were used in the left eye. After 1 day, serous retinal detachment was significantly decreased and anterior chamber inflammation disappeared in the right eye. After 1 week, no serous retinal detachment was observed. In the left eye, serous retinal detachment was decreased after using steroid eye drops. After 10 days, serous retinal detachment disappeared but anterior chamber inflammation was still observed. After 1 month, best corrected visual acuity was 1.0 in both eyes and serous retinal detachment had not recurred. On follow-up, VKH disease had not recurred and a healthy normal weight infant was delivered. Conclusions: Intravitreal triamcinolone injection is an effective and safe treatment for VKH disease in pregnant women.
곽현덕,김현웅,이지은,이주은,이상준,윤일한 대한안과학회 2014 대한안과학회지 Vol.55 No.4
Purpose: In recent, years, an increase of syphilis infections has become an issue in Korea as well as globally. Herein, we report a recent clinical manifestation of syphilitic uveitis in a Korean population. Methods: Over a 5-year period (2007-2012), we collected and analyzed the medical records of 16 patients with syphilitic uveitis in three tertiary eye clinics in Pusan. Sixteen patients were confirmed to have syphilis based on serological tests. Retrospective chart review was performed to determine the best corrected visual acuity, anterior and posterior segments, and treatment regimen, as well as ancillary test results including fluorescein angiogram (FAG). Results: Of the 16 patients, 12 were males and four were females. The mean age of the patients was 51.16 years. Non-granulomatous anterior uveitis was observed in nine eyes (47.4%). Vitritis was the most frequently observed posterior segment finding (16 eyes, 84.2%). Retinal vasculitis and chorioretinitis were found in 11 (57.9%) and five eyes (26.3%), respectively. All patients had negative results in the serum HIV antibody test. Of the 16 patients, 15 were treated with penicillin or ceftriaxone due to neurosyphilis. Mean visual acuity improved from 1.33 ± 1.1 to 0.58 ± 0.68 after treatment. Conclusions: Clinical manifestation of syphilitic uveitis in Korean patients is different from occurrences in Western countries. Ophthalmological findings of syphilitic uveitis are diverse; thus, serological testing for syphilis is recommended for all uveitis patients. Further research regarding long-term treatment, relapse of syphilitic uveitis, and complications is necessary. J Korean Ophthalmol Soc 2014;55(4):555-562
곽현덕(Hyun D. Kwak),전성민(Seong-Min Jeon),김진한(Jinhan Kim) 한국트라이볼로지학회 2010 한국윤활학회지(윤활학회지) Vol.26 No.6
An inter-propellant seal (IPS) for 75 ton class thrust turbopump was tested. Leakage characteristics were presented with a given range of pressure difference under cryogenic as well as room temperature conditions. For cryogenic tests, liquid nitrogen was used as analogic fluid of liquid oxygen (LOX) while water was used instead of kerosene for room temperature condition. Test results showed that IPS had satisfactory leakage performance. Additionally endurance test was conducted to prove the life time of manufactured IPS and the tested IPS had successfully survived during required life time, 2100 seconds.
곽현덕(Hyun D. Kwak),전성민(Seong-Min Jeon),김진한(Jinhan Kim) 한국트라이볼로지학회 2008 한국윤활학회지(윤활학회지) Vol.24 No.6
An inter-propellant seal (IPS) for high thrust turbopump is designed. With given operating conditions and requirements, the inter-propellant seal is designed to satisfy the leakage characteristics which is less than 0.1 % of normal flow rate of pumps. A numerical analysis is developed to predict the leakage flow rate. The results show that the maximum leakage of LOX and kerosene are less than 0.1 % of normal flow rate of pumps, respectively. Based on the numerical analysis results, the detail of IPS is performed, Finally a prototype of IPS is manufactured to perform sets of performance tests in the near future.
터보펌프 터빈 공력성능시험의 회전체 동역학적 진동분석사례
곽현덕(Hyun D. Kwak),윤석환(Suk-Hwan Yoon),전성민(Seong-Min Jeon),김진한(Jin-han Kim) 한국항공우주연구원 2006 항공우주기술 Vol.5 No.1
터보펌프 터빈 공력성능시험 중의 진동 특성을 측정하여, 정상상태 및 비정상상태에서의 진동의 크기, 시험시간 누적에 따른 진동의 변화추이를 분석하였다. 이를 바탕으로 비정상진동의 특성과 원인을 파악하였으며, 시험시간 누적에 따른 진동의 변화추이 분석을 통해 시험에 사용되는 볼 베어링의 수명 및 교체주기를 제시하였다. This report presents the analysis results of vibration characteristics concerning the aerodynamic performance test of turbopump turbine. In the means of measuring the acceleration during aerodynamic test, vibrational condition was carefully monitored. Based on the measured results the trend of vibration was analyzed and the ball bearing service time was suggested as well. In addition the cause of abnormal vibration, which was monitored during tests, was described.