• Journal of Yeungnam Medical Science
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• v.2 no.1
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• pp.241-247
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• 1985

Bacterial endocarditis has been well recognized as an important complication of congenital heart disease, such as ventricular septal defect, patent ductus arteriosus or pulmonary stenosis. The incidence of right sided bacterial endocarditis is lesser than left sided bacterial endocarditis. Also, pulmonic valve vegetation has been thought to be relatively uncommon. And pulmonary embolism is common in the patients with right sided bacterial endocarditis. So in a patient with fever and evidence of recurrent pulmonary infarction, changing heart murmurs and scattered pneumonic infiltrates, one should direct attention to the heart as a possible source of the infection. Echocardiography with M-mode, 2-D and Doppler mode represents the only noninvasive technic available for detecting vegetations in bacterial endocarditis. In fact, the technic is more sensitive in identifying these lesions than angiography. We experienced a case of ventricular septal defect with bacterial endocarditis, pulmonic valve vegetation and multiple pulmonary embolism diagnosed with Echocardiogram and lung scan, and confirmed by operation. Patch repair of ventricular septal defect, resection of pulmonic valve and vegetation and artificial valve formation with pericardium were done.

• 한국가시화정보학회:학술대회논문집
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• 2003.11a
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• pp.99-102
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• 2003

PIV(Particle Image Velocimetry)was used to visualize the interaction of reed valve of the reciprocating compressor. The valve is the key part which governs the efficiency, noise and reliability of the compressor, so the development of analytical model about valve performance is necessary. As the valve reed is opened and closed by pressure pulsation, the flow characteristic of the refrigerant passing the valve is very important. In the present study, a circular disk with inclination is assumed to be the valve reed of a reciprocating compressor, The mean velocity shows the vortical characteristic of this flow. It is found that the back flow is affected by the height of reed valve of reciprocating compressor.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.2
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• pp.184-193
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• 2006

Rotation of intake and exhaust valves are very closely related to the long term durability of automotive engines. If the valves do not rotate even at a rated engine speed, it causes the uneven wear of the valve seat and valve head contact area, which eventually shortens the engine life. A principle of valve rotation mechanism was presumed based on some findings from experiments, and computer programs were developed to simulate the valve rotation phenomena. In this study we investigated the valve rotation mechanism by using the computer simulation models.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.1
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• pp.184-192
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• 2022

Valve internal leakage is caused by damage to the internal parts of the valve, resulting in accidents and shutdowns of the piping system. This study investigated the possibility of a real-time leak detection method using the acoustic emission (AE) signal generated from the piping system during the internal leakage of a butterfly valve. Datasets of raw time-domain AE signals were collected and postprocessed for each operation mode of the valve in a systematic manner to develop a data-driven model for the detection and classification of internal leakage, by applying machine learning algorithms. The aim of this study was to determine whether it is possible to treat leak detection as a classification problem by applying two classification algorithms: support vector machine (SVM) and convolutional neural network (CNN). The results showed different performances for the algorithms and datasets used. The SVM-based binary classification models, based on feature extraction of data, achieved an overall accuracy of 83% to 90%, while in the case of a multiple classification model, the accuracy was reduced to 66%. By contrast, the CNN-based classification model achieved an accuracy of 99.85%, which is superior to those of any other models based on the SVM algorithm. The results revealed that the SVM classification model requires effective feature extraction of the AE signals to improve the accuracy of multi-class classification. Moreover, the CNN-based classification can be a promising approach to detect both leakage and valve opening as long as the performance of the processor does not degrade.

• Journal of Plant Biology
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• v.37 no.4
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• pp.417-420
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• 1994

Morphology of Achnanthes alteragracillima Lange-Bert. was studied with scanning electron microscopy in epilithic samples from the Kwang River (Kwangchun), Kyungsangbuk-Do, Korea. The species was characterized by the external raphe terminal fissure deflecting up to valve margin, the internal raphe proximal endings slightly deflecting to the opposite direction each other and biased hyaline area at the valve pole. It could be distinguished from A. minutissima K tz., closely related species, in having not straight external raphe terminal fissures, and from A. convergens H.Kob. in having a biased hyaline area at the valve pole and not a convergent striae arrangement at the pole of the raphe valve.

• Journal of Cardiovascular Imaging
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• v.26 no.4
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• pp.229-237
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• 2018

BACKGROUND: Statins are thought to have little effect on the progression of aortic stenosis, but the data on their role in patients with aortic valve sclerosis (AVS) are limited and inconsistent. METHODS: We retrospectively analyzed 541 consecutive patients (214 men, age: $70{\pm}11$ years) with AVS. Each patient underwent two or more electrocardiography examinations at least 6 months apart at Kangwon National University Hospital from August 2010 to August 2015. AVS is defined as irregular thickening of the leaflets, focal increases in echogenicity and minimal elevation of the peak aortic valve velocity (> 1.5 and < 2 m/s). The progression rate of AVS was expressed as the increase in peak velocity per year (m/s/yr). RESULTS: The mean follow-up duration was $24.9{\pm}13.3$ months in the statin-treated group and $24.1{\pm}12.4$ months in the non-statin-treated group (p = 0.460). There were no differences between the statin-treated and non-statin-treated groups in mean age, gender or smoking status. Relative to the non-statin-treated group, a higher number of patients in the statin-treated group had hypertension, diabetes, ischemic heart disease, and stroke. The progression rate of AVS did not differ between the statin-treated and non-statin-treated groups ($0.012{\pm}0.340m/s/yr$ vs. $0.014{\pm}0.245m/s/yr$, p = 0.956). Multivariate analysis showed initial peak aortic jet velocity was significantly associated with AVS progression (${\beta}=0.153$, p = 0.009). CONCLUSIONS: Our study demonstrated that statins had no effect on the progression of AVS. However, well-designed studies are needed to define the prognosis and management of AVS.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.3
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• pp.209-215
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• 2005

Since a transcritical $CO_2$ cycle shows lower performance than conventional air conditioners in the cooling mode operation, it is required to enhance the performance of the $CO_2$ cycle by applying advanced technologies and optimizing components. In this study, the cooling performance of a $CO_2$ system measured by varying refrigerant charge amount, compressor frequency, EEV opening and length of internal heat exchanger. As a result, the cooling COP of the basic system without internal heat exchanger was 2.1. The cooling performance of the modified cycle applying internal heat exchanger improved by $4-9\%$ over the basic cycle.

• Korean Journal of Veterinary Research
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• v.44 no.1
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• pp.125-129
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• 2004

A 2-year-old, female, American cocker spaniel dog presented for a 1-year history of severe ascites, exercise intolerance, tachypnea. At that time, she was in an emergency state. First, the dog was stabilized with oxygen therapy. A diagnosis of cardiac problem was made from history, auscultation, radiograph, ECG, and echocardiography. Jugular pulsation was palpated and a harsh, systolic murmur of tricuspid regurgitation was prominent at the right cardiac apex. Tricuspid valve dysplasia (TVD) was confirmed with echocardiography, accompanying enormous myocardial hypertrophy. The clinical signs had been improved for 8 months with careful therapy and periodic abdominocentesis, and ascites was well controlled. The situation, however, became worse quickly in a week because the client did not follow our management schedule. Finally, she died due to dyspnea and shock. After the spontaneous death, necropsy and histopathological examination were performed and when we opened the thorax, a significantly large heart was observed. On histopathological findings, grossly myocardium appeared pale initially, then progressed to yellow and white. Microscopically, there was an extensive hemorrhage along with loss of myocardial striations. Interstitial fibrosis and various degenerative alterations in myocytes were also present.

• 한국전산유체공학회:학술대회논문집
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• 2005.10a
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• pp.223-227
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• 2005

A PCV valve is a part to control the flow rate of Blowby gas in a PCV system. A PCV system re-burns Blowby gas with fuel in a combustion chamber. Some gas enters to a crankcase room through the gap between piston ring and engine cylinder wall. This gas si called 'Blowby gas'. This gas causes many problems. In environmental view, Blowby gas includes about $25\~35\%$ hydrocarbon{HC) of total generated HC in an automobile. Hydrocarbon is a very harmful pollutant element in our life. In mechanical view, Blowby gas has some reaction with lubricant oil of crankcase room. Then, this causes lubricant oil contamination, crankcase corrosion and a decrease fo engine efficiency. Consequently, Blowby gas must be eliminated from a crankcase room. In this study, we simulated internal flow characteristics in a PCV valve according to spool dynamic behavior using local remeshing method And, we programmed our sub routine to simulate a spool dynamic motion. As results, spool dynamic behavior is periodically oscillated by the relationship between fluid force and elastic force of spring. And its magnitude is linearly increased by the differential pressure between inlet and outlet. Also, as spool is largely moved, flow area is suddenly decreased at orifice. For this reason, flow velocity is rapidly decreased by viscous effect.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.2
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• pp.85-90
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• 2013

A numerical analysis for the internal flow was carried out in order to analyze the leakage flow characteristics inside the damped bypass valve. This research has found that the valve characteristics became stable at above a specific temperature. Very small amount of leakage flow was occurred. But there was no effect in temperature. The more temperature fell, the more maximum pressure rate was increased.