• 대한한방내과학회지
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• 제29권3호
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• pp.621-628
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• 2008

Objectives : The aim of this study was to investigate changes of gastric vagal nerve activity and pyloric valve function after execution of combination treatments of both electroacupuncture at Zusanli(ST36) and manual acupuncture at other acupoints in patient with functional dyspepsia. Methods : Bowel sounds of 49 patients (18 male, 31 female) were recorded and their % of bowel sound (%BS) and ratio of dominant frequency (DF) were analyzed. Postprandial %BS was used to indicate the gastric vagal activity after eating. Ratio of postprandial/fasting dominant frequency was used to present the degree of pyloric valve function. According to values of %BS and DF ratio, each patient was classified into normal or abnormal (<6 %BS, hypoactivity: <1 DF ratio, dysfunction) group. For 2 weeks, patients received a treatment consisting of both electroacupuncture stimulation at Zusanli (ST36) and acupuncture at other meridian points. Variation of parameters shifting normal to abnormal or abnormal to normal was observed, and total cure rate was calculated. Results : Total cure rate of %BS was 16%, and that of DF was 37%. Patients who improved to normal value from abnormal or aggravated to abnormal level showed both significant difference in both vagal nerve hypoactivity and pyloric valve dysfunction, respectively. Conclusions : Analysis of bowel sound might be useful to evaluate both gastric vagal nerve activity and pyloric valve function. Combination effects of Zusanli (ST36) electroacupuncture and manual acupuncture of other acupoints showed a bidirectional effect in which their activity and function were in general improved. sometimes from aggravated to abnormal level.

• 융합신호처리학회논문지
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• 제14권1호
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• pp.1-5
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• 2013

The two major problems related to the blood flow in replaced prosthetic heart valve are thrombus formation and hemolysis. Reliability of prosthetic valve is very important because its failure means the death of patient. There are many factors affecting the valvular failures and their representatives are mechanical failure and thrombosis, so early noninvasive detection is essentially required. The purpose of this study is to detect the various thromboses formation by using acoustic signal acquisition and its spectral analysis on the frequency domain. We made the thrombosis models using Polydimethylsiloxane (PDMS) and they are thrombosis model on the disc, around the sewing ring and fibrous tissue growth across the orifice of valve. Using microphone and amplifier, we measured the acoustic signal from the prosthetic valve, which is attached to the pulsatile mock circulation system. A/D converter sampled the acoustic signal and the spectral analysis is the main algorithm for obtaining spectrum. Then the spectrum of normal and 5 different kinds of abnormal valve were obtained. Each spectrum waveform shows a primary and secondary peak. The secondary peak changes according to the thrombus model. To quantitatively distinguish the frequency peak of the normal valve from that of the thrombosed valves, analysis using a neural network was employed. Acoustic measurement has been used as a noninvasive diagnostic tool and is thought to be a good method for detecting possible mechanical failure or thrombus.

• 한국세라믹학회지
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• 제35권2호
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• pp.163-171
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• 1998

Continuously contacting with camshaft the face of Valve Lifter made of cast iron brings about abnormal wear such as unfairwear or earlywear because it is heavily loaded in the valve train systems as the engine gets more powered. This abnormal wear becomes a defet namely over-clearance when the valve is lifting so that the fuel gas imperfectly combusted by unsuitable open or close aaction of the engine valve in the combustion chamber. The imperfect combustion in the end results in the major cause of air pollution and combustion chamber. The imperfectly combusted by unsuitable open or close action of the engine valve in the combustion chamber. The imperfect combustion in the end results in the major causes of air pollution and decrease of the engine output. Consequently to prevent this wear this study was to develop the valve lifter which is joined by brazing process with SCM435H and a tip by manufacturing the face as a superhardened which is joined by brazing process with SCM435H and a tip by manufacturing the face as a superhardened ceramics alloy which has high wear resistance. Having the excellent surface hardness with Hv1100-1200 the sintered body developed with superhardened alloy(WC) can endure the severe face loading in the valve train system. We experienced with various brazing alloys and obtained the excellent joining strength to the joint had 150MPa shear strength. Interface analysis and microstructure in a joint were examined through SEM & EDS Optical microscope. Also 2,500 hours high speed(3,000-4,000 rpm) and continuous (1step 12hr) engine dynamo testing was carried out to casting valve liter and ceramics-metal joint valve lifter so that the abnormal wears were compared and evaluated.

• 한국정밀공학회지
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• 제22권3호
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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.

• 한국수자원학회논문집
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• 제52권10호
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• pp.719-728
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• 2019

상수도 관망 밸브는 평상시 관로의 유향을 변경하는 역할을 하지만, 관로 파손, 수질 문제 등 사고 발생 시 해당 구역을 격리하는데에도 이용된다. 밸브조작에 의한 구역 단수는 주변 지역의 압력 및 물 공급 성능 저하를 유발한다. 최근 안정적인 상수도 관망 물 공급을 위협하는 사고가 다양하고 빈번하게 발생하고 있으며, 이에 따라 다양한 시나리오를 고려하여 밸브 위치 결정을 하는 것이 필요하다고 할 수 있다. 따라서 본 연구에서는 밸브의 개수, 구역격리 시 물 부족량, 수리학적 거리 인자(Hydraulic Geodesic Index, HGI)를 통합한 목적함수를 개발하고, 다양한 물 부족 시나리오에 기반한 밸브 최적 위치 결정 방법론을 제안한다. 제안한 방법론은 페스카라 관망에 적용되었으며, 시나리오별로 도출된 최적 밸브 설계안의 차이점을 분석하였다. 최적 밸브 위치 탐색 과정 중 수행된 관망 수리해석은 압력 기반(Pressure Driven Analysis, PDA)으로 수행하였다. 개발된 방법론으로 도출한 최적 밸브 설계안은 기존 설계안 대비 밸브 개수가 최대 19개나 적었고, 세그먼트 격리 시 물 공급 부족량 또한 상대적으로 작았다. 수원 수두가 낮은 시나리오를 고려할수록 더 많은 밸브가 설치되었는데, 밸브 추가 설치에 따른 비용증가는 다양한 시나리오에서 물 공급 성능 향상으로 이어짐을 확인하였다. 또한, 세그먼트 격리 상황 모의를 압력 및 유량 기반 해석으로 수행한 결과를 비교하여, 밸브 최적 위치 설계 수행 시 압력 기반 해석이 필요함을 확인하였다.

• 한국자동차공학회논문집
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• 제22권3호
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• pp.75-80
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• 2014

In previous study, make an attempt to estimate exhaust valve seat and seat-ring wear acceleration factor for engine durability test with measuring and consideration of wear mechanism. But found abnormal initial wear rate in exhaust valve seat-ring. And have to improve exhaust valve seat-ring wear rate for reliability reason, because next GDI/Turbo engine is based on this engine and GDI/Turbo engine have higher combustion pressure and higher thermal load. In this study, Trying to find the cause of abnormal wear factor, improve valve-train durability by change specification & design of parts and verify variant parts for improving durability of valve-train. And then I would like to propose a design guide line of valve-train system in a reliability point of view, besides make a complement of previous study.

• 한국세라믹학회지
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• 제35권2호
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• pp.172-179
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• 1998

Valve lifter namely tappet is supported by lifter hole which is located upper side of camshaft in cylinder block transforms rotatic mvement of camshaft into linear movement and helps to open and shut the en-gine valve as an engine parts. The face of valve lifter which is continuously contacting with camshaft brings about abnormal wears such as unfair wear and early wear because it is severely loaded in the valve train system. These wears act as a defect like over-clearance and cause imperfect combustion of fuel during the valve lifting in the combustion chamber. Consequently this imperfect combustion makes the engine out-put decrease and has cause on air pollution. To prevent these wears therefore The valve lifter cast in me-tal developed into SiC ceramics valve lifter which has an excellence in wear and impact resistance As a results the optimum process conditions like injection condition mixture ratio and debonding process could be established. After sintering fine-sinered dual microstructure in which prior ${\alpha}$-SiC matches well with new SiC(${\beta}$-SiC) produced by reaction among the ${\alpha}$-SiC carbon and silicon was obtained. Based on the study it is verified that mechanical properties of SiC valve lifter are excellent in Vickers hardness 1100-1200 bending strength (300-350 Pa) fracture toughness(1.5-1.7 Mpa$.$m1/2) Through engine dynamo test-ing SiC valve lifter and metal valve lifter are examined and compared into abnormal phenomena such as early fracture unfair and early wear. It is hoped that this research will serve as an important springboard for the future study of heavy duty diesel engine parts developed by ceramics which has a good wear resis-tance relaibility and lightability.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.2100-2104
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• 2004

Amount of Electricity which product generator decide control valve at Turbine. Operating method of Control valve have two mode. First operating method is Partial Arc Admission, and second operating method is Full Arc Admission. Failure of Control Valve have on serious damage electricity lineage. In this Paper, We have investigated resonance that Control Valve spring casing.

• 동력기계공학회지
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• 제3권4호
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• pp.28-35
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• 1999

An application of scroll compressor to the residential air conditioning and heat pump markets has generated many reliability problem, especially abnormal noise. Most of these noise problems is due to the check valve and compliance between FS(Fixed Scroll) and OS(Orbiting Scroll). FS and OS are the main parts of scroll compressor and are the main pumping part. But check valve has the role of protection of reverse rotation of OS when power is off. Check valve have several noise problems. Among them, shut down noise and valve movement noise is more than severe than any other problem. In this paper covers with these two noise problem.

• 한국동물위생학회지
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• 제46권1호
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• pp.75-79
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• 2023

An eight-year-old, 28-kg male bull terrier who showed signs of lethargy and cough was referred for further evaluation of congestive heart failure. On presentation, physical examination revealed a systolic murmur at the left apex of the heart. Moreover, chest radiograph evaluation confirmed the mild alveolar and interstitial patterns in the caudal lung lobes and a grossly enlarged left atrium and left ventricle. Electrocardiography showed atrial fibrillation with a wide QRS complex, and transthoracic echocardiography revealed marked enlargement of the left atrium with abnormal morphology of the mitral valve. The thickened, hammer-like appearance and abnormal diastolic motion of the mitral valve leaflets were characterized by decreased leaflet separation and doming of the valve. The diagnosis was mitral stenosis with congestive heart failure and atrial fibrillation. The owner declined interventional valvuloplasty. Medical treatment included furosemide, pimobendan and diltiazem. Regular health check-ups have shown that vitality and clinical signs have improved considerably, and the dog have remained stable for 6 months after the presentation.