• Journal of the Korean Society of Safety
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• v.11 no.2
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• pp.42-51
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• 1996

Taper roller bearing is used on rotating shaft where radial and thrust loads are attended. To avoid the sudden failure and maintain the good condition of rotating machinery it is necessary to monitor the condition of bearing and diagnose the defect of bearing. In this study the diagnosis program of taper roller bearing which is used on the lower bearing of V.A.W.T. (Vertical Axis Wind Turbine) is developed. By plenty of test the database is constructed and by Gaussian distribution obtained from database the defect probability of bearing is calculated.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.46 no.6
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• pp.428-434
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• 2020

Orbital floor blowout fractures can result in a variety of signs and symptoms depending on the severity of the bone defect. Large defects often result in enophthalmos and restriction of ocular movement; yet the timing of surgery can be delayed up to two weeks with good functional outcomes. In contrast, an orbital trapdoor defect with entrapment of the inferior rectus muscle usually elicits pain with marked restriction of the upward gaze and activation of the oculocardiac reflex without significant dystopia or enophthalmos. When autonomic cardiac derangement is diagnosed along with an orbital floor fracture, it has been suggested that the fracture should be treated immediately. Otherwise, it will result in continued hemodynamic instability and muscular injury and may require a second surgery. This article reports the management of an unusual presentation of a trapdoor blowout orbital floor fracture surgery with oculocardiac response in an adult, with emphasis on its pathophysiology, management, and differential diagnosis.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.3
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• pp.63-69
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• 1996

Recently, vibrational signal processing as a tool of machinery diagnosis has been actively studying. In this study, a new scheme for detection and diagnosis of localized defects in ball bearings, using unwrapped phase spectrum of FFT is described. The characteristic phase spectra for such defects shows linearly varying patterns due to the repetitive impact signals generated by localized defects, i.e., one linear line for single defect and various linearly changing shape according to angle between the two defect located points. The effectiveness of this method is confirmed by computer simulation and experiments on bearing with single or double defects at different locations.

• The KIPS Transactions:PartA
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• v.17A no.2
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• pp.81-92
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• 2010

There has been some research in the equipment defect detection based on vibration information. Most research of them is based on vibration monitoring to determine the equipment defect or not. In this paper, we introduce more accurate system for engine defect detection based on vibration information and we focus on detection of engine defect for boat and system control. First, it uses the duplicated-checking method for vibration information to determine the engine defect or not. If there is a defect happened, we use the method using error part of vibration information basis with error range to determine which kind of error is happened. On the other hand, we use the engine trend analysis and standard of safety engine to implement the vibration information database. Our simulation results show that the probability of engine defect determination is 100% and the probability of engine defect classification and detection is 96%.

• Journal of Chest Surgery
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• v.16 no.3
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• pp.331-336
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• 1983

Cor triatriatum is a rare congenital malformation of the heart, in which a septum stretches in a transverse or oblique plane through the left atrium, thus separating it into two compartments. The upper one connects with the pulmonary veins, and the lower one connects with the left ventricle. Due to the rarity of, and great difficulty in-diagnosing, cor trlatrlatum, data On the surgery of this disease are of necessity very limited and so accurate pre-operative diagnosis was very difficult to make. `We experienced a case of the cyanotic congenital heart disease which was diagnosed as a large atrlal septal defect with streaming venous blood from inferior vena cava to left atrium through atrial septal defect in August, 1982. We found that there were transverse septum in the left atrium through atrlal septal defect, the pulmonary venous drainage were located in the upper chamber of the left atrium, and the lower chamber was connected with the left atrial appendage, mitral valve and `left ventricle. But our case had not any opening in this transverse septum and the right atrium was connected with the upper chamber of the left atrium through the upper part of the atrlal septal defect, and was communicated with the lower chamber of the left atrium through the lower part of the atrlal septal defect. We excised the transverse septum and repair this atrial septal defect with Woven Dacron patch accompanying with the drainage of coronary sinus to right atrium. The post-operative course was not eventful and he was discharged with good result on the post-operative 8th day, and has been in good .condition up to now for longer than 10 months.

• Journal of Chest Surgery
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• v.14 no.4
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• pp.399-402
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• 1981

Because of recent advances in cardiac surgery and diagnostic techniques, left ventricular-right atrial communication has been reported with increasing frequency. Recently we experienced 2 cases of left ventricular-right atrial communication, which were corrected surgically. Preoperative diagnosis was incorrect In both cases as ventricular septal defect. The type of defect was supravalvular in case 1 and case 2. Both cases were successfully closed with the aid of extracorporeal circulation and discharged with good results.

• Journal of Chest Surgery
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• v.19 no.3
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• pp.506-514
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• 1986

Coarctation of aorta is rather common congenital cardiovascular defect in the western countries, but it is known to be rare in Korea. And no coarctation of Aorta has been reported and operated upon during early infancy in Korea. During 4 months period from May 1984 to September 1984, four small infants of coarctation of aorta were seen and treated surgically by subclavian flap aortoplasty in Guro Hospital, Korea University. All infants were male, ranging from 7 days to 54 days old [mean 29 days], weighing between 3.2 Kg and 5.0 Kg [mean 4.1 Kg], and all were in congestive heart failure. Examination of the femoral artery pulse gave in all cases clues to the diagnosis. By Two dimensional echocardiogram, detail anatomical features as well as the diagnosis were revealed and associated anomalies, for example, ventricular septal defect could be seen. Besides one case of isolated coarctation of aorta, other three infants had associated VSD. The 3 patients with VSD were treated by pulmonary artery banding in addition to aortoplasty. The postoperative course were smooth in all patients. In conclusion, coarctation of aorta may not be so rare in Korea as we thought previously. The importance of femoral pulse examination can not be overemphasized for the diagnosis. As we experienced, two-dimensional echocardiography in most cases can substitute those invasive examinations such as angiography and catheterization which carry difficulty and risk in infants.

• Investigative Magnetic Resonance Imaging
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• v.20 no.2
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• pp.114-119
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• 2016

We report a case of vegetation in a 4-year-old female with infective endocarditis, diagnosed by late gadolinium-enhanced (LGE) cardiovascular magnetic resonance (CMR) imaging. The patient had a history of primary closure for ventricular septal defect and presented with mild febrile sensation. No remarkable clinical symptoms or laboratory findings were noted; however, transthoracic echocardiography demonstrated a 14 mm highly mobile homogeneous mass in the right ventricle. On LGE CMR imaging, the mass showed marginal rim enhancement, which suggested the diagnosis of vegetation rather than thrombus. The extracellular volume fraction (${\geq}42%$) of the lesion was higher than that of normal myocardium. Based on the patient's clinical history of congenital heart disease and pathologic confirmation of the lesion, a diagnosis of infective endocarditis with vegetation was made.

• Journal of the Korean institute of surface engineering
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• v.54 no.6
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• pp.348-356
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• 2021

In this study, optical diagnosis of plasma was performed for nitrogen doping in graphene using a horizontal inductively coupled plasma (ICP) system. Graphene was prepared by mechanical exfoliation and the ICP system using nitrogen gas was ignited for plasma-induced and defect-suppressed nitrogen doping. In order to derive the optimum condition for the doping, plasma power, working pressure, and treatment time were changed. Optical emission spectroscopy (OES) was used as plasma diagnosis method. The Boltzmann plot method was adopted to estimate the electron excitation temperature using obtained OES spectra. Ar ion peaks were interpreted as a reference peak. As a result, the change in the concentration of nitrogen active species and electron excitation temperature depending on process parameters were confirmed. Doping characteristics of graphene were quantitatively evaluated by comparison of intensity ratio of graphite (G)-band to 2-D band, peak position, and shape of G-band in Raman profiles. X-ray photoelectron spectroscopy also revealed the nitrogen doping in graphene.

• Journal of the Korea Society of Computer and Information
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• v.28 no.2
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• pp.9-17
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• 2023

In this paper, we propose a one-class vibration anomaly detection system for bearing defect diagnosis. In order to reduce the economic and time loss caused by bearing failure, an accurate defect diagnosis system is essential, and deep learning-based defect diagnosis systems are widely studied to solve the problem. However, it is difficult to obtain abnormal data in the actual data collection environment for deep learning learning, which causes data bias. Therefore, a one-class classification method using only normal data is used. As a general method, the characteristics of vibration data are extracted by learning the compression and restoration process through AutoEncoder. Anomaly detection is performed by learning a one-class classifier with the extracted features. However, this method cannot efficiently extract the characteristics of the vibration data because it does not consider the frequency characteristics of the vibration data. To solve this problem, we propose an AutoEncoder model that considers the frequency characteristics of vibration data. As for classification performance, accuracy 0.910, precision 1.0, recall 0.820, and f1-score 0.901 were obtained. The network design considering the vibration characteristics confirmed better performance than existing methods.