• Transactions of the Korean Society of Mechanical Engineers B
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• v.32 no.5
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• pp.400-405
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• 2008

Air-operated valve is one of principal valves that are used to control fluid flow in nuclear power plants. It is necessary to evaluate periodically the performance of the AOV(Air-Operated Valve) which is used for controlling flow and pressure in nuclear power plants. In this study, we developed the integrated program HAES including hardware system to evaluate the performance of AOV. HAES(HANVIT AOV Evaluation System) consists of many modules such as valve information, thrust and torque analysis, actuator analysis, weak analysis and margin analysis. We applied with the test valve and showed that results evaluated by HAES is similar to those offered in the plant.

• Transactions of The Korea Fluid Power Systems Society
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• v.6 no.2
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• pp.22-30
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• 2009

An in-process method of diagnosing the spool wear of hydraulic servovalves was explored. The diagnostic method discussed in this paper is for force-control hydraulic servo systems. The key principle used is that pressure sensitivity of a servovalve drops as the valve spool wears out so that it is possible to determine the spool condition by monitoring pressure sensitivity. A diagnostic algorithm was developed and evaluated through numerical simulation and experiments. Two major steps of diagnosis are the evaluation of null bias of the servovalve and the approximation of pressure sensitivity, both of which could be successfully done during normal operation of a servo system. The difference between a new servovalve and a worn valve could be clearly detected in-process, and the diagnostic test was found to be repeatable.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.18 no.10
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• pp.791-799
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• 2006

The fault diagnosis technologies may be applied in order to decrease the energy consumption and the maintenance cost of an air-conditioning system. In this paper, a fault diagnosis algorithm was developed by using a neural no-fault model and a dual fuzzy logic. Five different faults, such as the compressor valve leakage, the liquid line blockage, the condenser fouling, the evaporator fouling, and the refrigerant leakage of an air-conditioning system, were considered. The fault diagnosis algorithm was tested by using a fault simulation facility. Test results showed that the algorithm developed for this study was effective to detect and diagnose various faults. Therefore, this algorithm may be practically used for the fault diagnosis of an air-conditioning system.

• 유체기계공업학회:학술대회논문집
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• 2004.12a
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• pp.481-487
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• 2004

Air-operated valve is one of principal valves that are using to control fluid flow in nuclear power plants. A period diagnosis lot safety of power plants is necessary. But there are many difficulties such as economic loss caused by income of high cost devices and a matter hard to deal with users. In this study, we developed the diagnostic system that users of power plants are easy to handle. The diagnostic system is composed of database module, diagnosis test module and evaluation module.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.3 s.168
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• pp.123-129
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• 2005

The unbalance of the power output, noise, and vibration is happened by the disproportionate pressure variation in the cylinder. For this reason, decrease of the pressure in the cylinder and increase of the residual gas effect on the engine performance. If the abnormal combustion is continued, the crack would be occurred in the engine block. And it could be broken down. For the normal combustion of the SI engine, it is important to supply the balanced mixture by each operating condition. In this study, it was tested the combustion characteristics in the cylinder according to the abnormal adjusting of intake & exhaust valve. This test is willing to set a basic data's analysis fur developing an automotive diagnosis system by analyzing the pressure in the cylinder, the output signal of MAP sensor, the exhaust gas, etc.

• Journal of Chest Surgery
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• v.20 no.4
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• pp.809-814
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• 1987

Myxoma is a benign growth constituting nearly 50% of all primary cardiac tumors. It is important because in can be abolished by surgical therapy and is usually fatal if unrecognized and untreated. Primary cardiac tumors are uncommon in all age group. In contrast, tumors metastatic to the heart are significantly more common. The diagnosis is made by echocardiography and cardiac angiography. Recently a wider use of echocardiogram as the screening test of valve lesions can be expected to increase the number of myxomas found preoperatively. We report the two cases of left atrial myxomas which were removed successfully by surgery in the thoracic and cardiovascular surgery department, Marryknoll Hospital.

• Journal of Korean Neurosurgical Society
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• v.60 no.1
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• pp.1-7
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• 2017

Objective : The diagnosis of shunt malfunction can be challenging since neuroimaging results are not always correlated with clinical outcomes. The purpose of this study was to evaluate the efficacy of a simple, minimally invasive cerebrospinal fluid (CSF) lumbar tapping test that predicts shunt under-drainage in hydrocephalus patients. Methods : We retrospectively reviewed the clinical and radiological features of 48 patients who underwent routine CSF lumbar tapping after ventriculoperitoneal shunt (VPS) operation using a programmable shunting device. We compared shunt valve opening pressure and CSF lumbar tapping pressure to check under-drainage. Results : The mean pressure difference between valve opening pressure and CSF lumbar tapping pressure of all patients were $2.21{\pm}24.57mmH_2O$. The frequency of CSF lumbar tapping was $2.06{\pm}1.26times$. Eighty five times lumbar tapping of 41 patients showed that their VPS function was normal which was consistent with clinical improvement and decreased ventricle size on computed tomography scan. The mean pressure difference in these patients was $-3.69{\pm}19.20mmH_2O$. The mean frequency of CSF lumbar tapping was $2.07{\pm}1.25times$. Fourteen cases of 10 patients revealed suspected VPS malfunction which were consistent with radiological results and clinical symptoms, defined as changes in ventricle size and no clinical improvement. The mean pressure difference was $38.07{\pm}23.58mmH_2O$. The mean frequency of CSF lumbar tapping was $1.44{\pm}1.01times$. Pressure difference greater than $35mmH_2O$ was shown in 2.35% of the normal VPS function group (2 of 85) whereas it was shown in 64.29% of the suspected VPS malfunction group (9 of 14). The difference was statistically significant (p=0.000001). Among 10 patients with under-drainage, 5 patients underwent shunt revision. The causes of the shunt malfunction included 3 cases of proximal occlusion and 2 cases of distal obstruction and valve malfunction. Conclusion : Under-drainage of CSF should be suspected if CSF lumbar tapping pressure is $35mmH_2O$ higher than the valve opening pressure and shunt malfunction evaluation or adjustment of the valve opening pressure should be made.

• Journal of Veterinary Clinics
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• v.22 no.4
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• pp.396-400
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• 2005

A 13-year old, female Maltese dog was presented due to a five-month history of episodic syncope. A diagnosis of sick sinus syndrome (SSS) with mitral valve endocardiosis (MVE) was made based on history takings, physical and cardiac examination, complete blood count (CBC), serum chemistry profiles, radiography, electrocardiography (ECG), atropine response test, hormonal assay, and echocardiography. In this case, SSS was definitely diagnosed by evaluation of ECG recording following atropine administration. Clinical signs were improved with medical management of theophylline (THEOLAN, KunWha Pharm, Seoul, Korea, 20 mg/kg, PO, BID). After 10 more month survival, the dog, died of respiratory distress and shock during the operation of abdominal mass removal in local animal hospital. Unfortunately, we were not able to perform necropsy after death due to owner's decline. This case demonstrates that theophylline can be used in management oF dog with SSS.

• Journal of Veterinary Clinics
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• v.34 no.3
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• pp.213-217
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• 2017

A 1-year and 8-month-old male, thoroughbred horse showed fever ($39.8^{\circ}C$), cardiac murmur, tachycardia up to 80 beats/min, anorexia, depression and lameness for about 2 months. The dead horse was referred to pathology laboratory at the College of Veterinary Medicine in Jeju National University. At necropsy, Severe protruding multiple rough cauliflower-like yellowish red nodules ranged $5{\sim}6{\times}2{\sim}3cm$ in size were attached on the mitral valve of the left heart. A yellowish red long stick-shaped thrombus $15{\times}3.5{\times}1.5cm$ in size was also present inside the right ventricle. Multifocal infarcts were scattered in the myocardium and renal cortex. Histopathologic examination revealed that morphologic diagnosis were vegetative endocarditis, thrombus in right ventricle, infarcts in myocardium and kidney, pulmonary congestion and edema, and splenic congestion. The isolated bacteria from vegetative lesions and thrombus were confirmed as Escherichia (E.) coli based on the bacterial culture and VITEK 2 system. Based on the gross and histopathologic features, and bacterial test, this case was diagnosed as vegetative endocarditis with thrombus formation associated by E. coli in a thoroughbred horse.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2606-2611
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• 2008

The high energy fluid leakage from the high temperature and high differential pressure drop system of NPPs (Nuclear Power Plants) decreases efficiency and consequently leads to considerable economic loss due to less power production. Also, the leakage possibly damages critical parts of components such as valve and trim with the effect of cavitation, flashing, and erosion, etc. and deteriorates its performance. Thus, in this study, we diagnosed the as-is leakage for four (4) main steam drain valves and two (2) steam traps of Yonggwang 1,2 units during normal operation by using multi-measuring technique and observed the occurrence of fine leakage. In the course of measuring fluid leakage, the sign of fine leakage is estimated to be the leakage from orifice. By converting the leakage to energy loss, it is equivalent to the amount of several hundred thousand won per each unit, which supports the basis for the justification of fine leakage.