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베어링 마모시험을 이용한 진동신호의 통계적 파라미터 특성연구
전오성,황철호,윤병옥,은희준,Jun, Oh-Sung,Hwang, Cheol-Ho,Yoon, Byung-Ok,Eun, Hee-Joon 한국음향학회 1989 韓國音響學會誌 Vol.8 No.1
RMS, Kurtosis, Crest factor, Probability of exceedance와 Probability density function 등의 통계적 파라미터를 선정하여 베어링의 사용조건과 결함진전에 따른 변화특성을 조사하였다. 이를 위해 4볼 시험기에서 하중, 회전수 및 시간을 변화시키면서 실험하여 진동신호를 수집하고, 이를 A/D변환시킨 후 디지털 필터링하여 주파수 대역별 통계적 파라미터 값을 계산하였다. 실험결과, 하중이나 회전수와 같은 운전조건이 변화하는 경우 RMS의 값은 운전조건 변화에 따라 변하지만 Kurtosis 등의 통계적 파라미터들은 운전조건과 무관하게 steady한 결과를 나타내었다. 또한 통계적 파라미터와 시간과의 상관관계에 대한 실험으로부터 통계적 파라미터들을 결함의 진전 상태를 나타내는 파라미터로 사용할 수 있음을 확인하였으며, 따라서 파손방지를 위한 예측지표로서 이들 통계적 파라미터를 이용할 수 있을것으로 판단되었다. This paper is concerned with the characteristics on the statistical parameters of vibration signal from bearing with changing its operating conditions as well as the spreading of faults. The rms, Kurtosis, crest factor, probability of exceedance and probability density function have been chose as the statistical parameters. To characterize of each, vibration signals have been recorded from four ball tester at different loads, operation speeds and time. The values of the statistical parameters for each frequency band have been calculated after A/D conversion and digital filtering of the recorded signals. It has been found that unlike rms values the statistical parameters such as Kurtosis etc. are almost unchanging with the change of the operating conditions such as load and speed. This suggests that the statistical parameters may be used for determining the development of faults independent of the operating conditions. In fact, the statistical parameters deviate considerably from their respective normal values when the faults developed under load conditions in the samples, conforming the suggestion.
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횡 방향 플립 칩 초음파 접합 시 혼의 공차변수가 시스템의 진동에 미치는 영향
정하규(Ha Kyu Jung),권원태(Won Tae Kwon),윤병옥(Byung Ok Yoon) 한국생산제조학회 2009 한국생산제조학회지 Vol.18 No.1
Thermosonic flip chip bonding is an important technology for the electronic packaging due to its simplicity, cost effectiveness and clean and dry process. Mechanical properties of the horn and the shank, such as the natural frequency and the amplitude, have a great effect on the bonding capability of the transverse flip chip bonding system. In this research, two kinds of study are performed. The first is the new design of the clamp and the second is the effect of tolerance parameters to the performance of the system. The clamp with a bent shape is newly designed to hold the nodal point of the flip chip. The second is the effect of the design parameters on the vibration amplitude and planarity at the end of the shank. The variation of the tolerance parameters changes the amplitude and the frequency of the vibration of the shank. They, in turn, have an effect on the quantity of the plastic deformation of the gold ball bump, which determined the quality of the flip chip bonding. The tolerance parameters that give the great effect on the amplitude of the shank are determined using Taguchi’s method. Error of set-up angle, the length and diameter of horn and error of the length of the shank are determined to be the parameters that have great effect on the amplitude of the system.
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양동호,오명진,김재한,윤병옥,서기현,홍세용,김의한 대한신장학회 1999 Kidney Research and Clinical Practice Vol.18 No.6
Spontaneous renal allograft rupture is an uncommon complication of renal transplantation, but it represents a life-threatening emergency that requires prompt recognition and treatment. The incidence of spontaneous renal allograft rupture is variable and range between 3.6 and 9.6 percent of all transplants. In the majority of cases the rupture is associated with acute rejection episodes and with renal vein thrombosis. Most frequently, the allograft rupture occurs within the first 2 weeks of transplantation. in addition, most ruptures reported have occurred in cadaveric renal allograft. Debate on the management of such allograft salvage versus transplant nephrectomy. It appears that the recent trend is toward performing surgical repair of the graft if the rupture is secondary to rejection and oo evidence of renal vein thrombosis ; otherwise, graft nephrectomy be done. We report a case of spontaneous renal allograft rupture due to renal vein thrombosis occurred in a 21-year-old woman 6 days after transplantation. Unusual severe localized pain, swelling over at allograft site, and hypotension, a triad frequently seen in renal allograft rupture, were present. Management by graft nephrectomy was inevitable because of the patient's downhill course.
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Methimazole 유발 담즙울체성 황달예에서 스테로이드사용 1예
김완섭,김영민,유명희,서교일,김철희,변동원,김재한,윤병옥,송상훈,오명진,황헌규 대한내분비학회 1999 Endocrinology and metabolism Vol.14 No.3
Cholestatic jaundice caused by imidazole derivatives is a rare complication of antithyroid drug therapy. We present a case of cholestatic jaundice with systemic hypersensitivity reaction, which developed in a 27-year old male one day after exposure to methimazole. The patient showed clinical improvement and gradual resolution of jaundice after the discontinuation of methimazole and treatment with prednisolone. Histologic findings of liver revealed bile pigment, predominantly in centrilobular area, and infiltration of chronic inflammatory cells in a few portal area without evidence of degeneration or necrosis of hepatocytes. Methimazole could be presumed as etiologic agent from clear chronological relationship and the lack of other causative factors. We report this unusual case with review of literature (J Kor Soc Endocrinol 14:592-598, 1999).
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용종성종괴모양을 보인 십이지장 팽대부의 협착성 유두염 1예
박승철,김홍수,이문호,김선주,김대중,윤병옥,박상흠,정일권,오흥석,황헌규,박관석,전 진 대한소화기내시경학회 1999 Clinical Endoscopy Vol.19 No.2
$quot;Stenosing papillitis$quot; is a descriptive term for an anatomic deformity of the Ampulla of Vater due to chronic inflammation and fibrosis, which is characterized by narrowing of the lower end of the bile and pancreatic duct, and by clinical symptoms resembling pancreticobiliary disease. Duodenoscopic finding of stenosing papillitis usually shows edema, erythema, and laceration on Ampulla of Vater, but endoscopic finding such as polypoid mass is rare. We recently experienced one case of polypoid stenosing papillitis and report with a review of relevant literatures A 54-year-old man was admitted to our hospital because of chronic right upper abdominal pain for 2 years. Duodenoscopy revealed a polypoid mass with erythemaous color change on Ampulla of Vater, which was endoscopically resected by using a polypectomy snare, and pathologic examination showed chronic inflammation and fibrosis.
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