• Transactions of the Korean Society of Automotive Engineers
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• v.4 no.1
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• pp.110-122
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• 1996

The objective of this study is to understand the dynamic characterictics of OHV type valve trains and to design and optimal cam profile which will improve engine performance. A numerical model for valve train dynamics is presented, which aims at both accuracy and computational efficiency. The lumped mass model and distributed parameter model were used to describe the valve train dynamics. Nonlinear characterictics in the valve spring behavior were included in the model. Comprehensive experiments were carried out concerning the valve train dynamics, and the model was tuned based on the test results. The dynamic model was used in designing an optimal cam profile. Because the objective function has many local minima, a conventional local optimizer cannot be used to find an optimal solution. A modified adaptive random search method is successfully employed to solve the problem. Cam lobe area could be increased up to 7.3% without any penalties in kinematic and dynamic behaviors of the valve train.

• 한국태양에너지학회:학술대회논문집
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• 2011.11a
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• pp.338-341
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• 2011

Water usage for cleaning the toilet bowl accounts for 27% of the total water usage. Water-saving valve that can select the amount of water for cleaning toilet bowl can be reduced expenditure. After installing water-saving valve, analysed the economic effects. Water-saving valves compared with flush valves, and researched the amount of water usage. Then analyzed fort he economic effects. Water-saving valve was used 5.6 ${\ell}/time$ for cleaning toilet bowl. In contrast, flush valve was consumed 8.4 ${\ell}/time$. Water-saving valve's water-saving rate was 33.3%. The initial payback period for Water-saving valve was 459.5 days. By a small investment in water saving valve, the economic benefits can be obtained.

• Journal of Biomedical Engineering Research
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• v.12 no.3
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• pp.149-156
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• 1991

In this paper, fluttering behavior of mechanical bileaflet heart valve prosthesis was analyzed taking into consideration of the impact between valve plate and stopper Vibration system of the valve was modeled as a rotating system, and equations are induced by moment equilibrium equations. Lift force, drag force, gravity and buoyancy were considered as external forces acting on the valve plate/ The 4th order Runge-Kutta method was used to solve the equations. Valve plate does not come to the static equilibrium position at a stretch, but come to that position after under damping vibration. Damping ratio increases as the cardiac optput increases, and the mean damping ratio is in the range of 0.16~40.25. Fluttering frequency does not have any specific value, but varies as a function of time. It is in the range of 10~40Hz. Valve opening appears to be affected by the orientation of the of the valve relative to gravitational forces.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.19 no.6
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• pp.883-888
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• 2010

This study have goal with conceptual design for Offshore Structures of high pressure control valve for localization. Ball valve for development accomplished with flow analysis based on provision of ANSI B16.34, ANSI B16.10, ANSI B16.25 In order to localize the Offshore Structures high pressure control valve. Numerical simulation using CFD (Computational Fluid Dynamic) in order to predict a mass flow rate and a flow coefficient form flow dynamic point of view. The working fluid assumed the glycerin (C3H8O3). The valve inlet and outlet setup a pressure boundary condition. The outlet pressure was fixed by atmospheric pressure and calculated until increasing 1bar to 10bar. CFD analysis used STAR-CCM+ which is commercial code and Governing equations were calculated by moving mesh which is rotated 90 degrees when ball valve operated opening and closing in 1 degree interval. The result shows change of mass flow rate according to opening and closing angle of valve, Flow decrease observed open valve that equal percentage flow paten which is general inclination of ball valve. Relation with flow and flow coefficient can not be proportional according to inlet pressure when compare with mass flow rate. Because flow coefficient have influence in flow and pressure difference. Namely, flow can be change even if it has same Cv value. The structural analysis used ANSYS which is a commercial code. Stress analysis result of internal pressure in valve showed lower than yield strength. This is expect to need more detail design and verification for stem and seat structure.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.1195-1200
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• 2008

This study have goal with conceptual design for Offshore Structures of high pressure control valve for localization. Ball valve for development accomplished with flow analysis based on provision of ANSI B16.34, ANSI B16.10, ANSI B16.25 In order to localize the Offshore Structures high pressure control valve. Numerical simulation using CFD(Computational Fluid Dynamic) in order to predict a mass flow rate and a flow coefficient form flow dynamic point of view. The working fluid assumed the glycerin($C_3H_8O_3$). The valve inlet and outlet setup a pressure boundary condition. The outlet pressure was fixed by atmospheric pressure and calculated until increasing 1bar to 10bar. CFD analysis used STAR-CCM+ which is commercial code and Governing equations were calculated by moving mesh which is rotated 90 degrees when ball valve operated opening and closing in 1 degree interval. The result shows change of mass flow rate according to opening and closing angle of valve. Flow decrease observed open valve that equal percentage flow paten which is general inclination of ball valve. Relation with flow and flow coefficient can not be proportional according to inlet pressure when compare with mass flow rate. Because flow coefficient have influence in flow and pressure difference. Namely, flow can be change even if it has same Cv value. The structural analysis used ANSYS which is a commercial code. Stress analysis result of internal pressure in valve showed lower than yield strength. This is expect to need more detail design and verification for stem and seat structure.

• Journal of Chest Surgery
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• v.37 no.7
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• pp.559-569
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• 2004

The CarboMedics mechanical valve has been reported to show acceptable valve-related complication rates. The aim of this study is to evaluate our clinical experience with the CarboMedics valve. Material and Method: Between August 1988 and September 1999, we implanted 1,144 CarboMedics valves in 850 patients (aortic 179; mitral 385; double-valve 234; tricuspid 52). The mean age was 44.5 $\pm$ 12.5 years. Follow-up was completed in 95.2% and median follow-up period was 7.9 years (6753 patient-years). Result: The overall hospital mortality rate was 3.4% and the mortality rate for each group was 1.7% for aortic group, 2.6% for mitral group, 4.7% for double-valve group, and 9.6% for tricuspid group, Tricuspid group showed significantly higher mortality rate than aortic and mitral group (p〈0.05). The actuarial survival at 10 years was 87.1 $\pm$ 2.6%, 88.9 $\pm$ 1.7%, 82.4 $\pm$ 2.9%, and 77.5 $\pm$ 7.0% for aortic, mitral, double, and tricuspid valve group, respectively. Age and tricuspid valve replacement were significant risk factors for long-term survival in multivariate analysis (p 〈 0.05). Freedom from valve thrombosis at 10 years was 99.4 $\pm$ 0.6%, 98.2 $\pm$ 0.8%, 99.2 $\pm$ 0.8%, and 87.6 $\pm$ 0.5% for aortic, mitral, double and tricuspid valve group. Tricuspid valve group showed significantly higher rate of valve thrombosis (p 〈 0.05). Conclusion: Long-term results of our experience demonstrated that CarboMedics valve showed acceptable incidence of valve-related complications. However, tricuspid valve replacement showed higher rate of early mortality and valve thrombosis than other valve replacement groups.

• Journal of Chest Surgery
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• v.23 no.3
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• pp.527-531
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• 1990

A 11 year-old girl with quadricuspid aortic avlve associated with regurgitation left superior vena cava and chromosomal anomaly is presented. The quadricuspid valve was unexpectedly found during operation for aortic valve replacement. The aortic valve consisted of 4 equal-sized cusps and retrospective review of the aortogram revealed the aortic valve to have 4 cusps also. To the best of our knowledge, this combination of anomalies has not been reported in Korea previously.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.3
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• pp.120-124
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• 2003

Monoleaflet polymer artificial heart valve was known to show remarkable improvement in antithrombosis and pressure drop compared with other type of artificial valve. In this investigation of monoleaflet heart valve the vertical and horizontal deflection pattern of polymer heart valve with three types of supporting members, straight member and two curved members were analysed using the large deformation nonlinear finite element method.

• Journal of Chest Surgery
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• v.28 no.12
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• pp.1107-1112
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• 1995

Between December 1993 and December 1994, fifty-eight percent of the mitral valve patients[33/57 had undergone mitral valve repair. Their mean age was 49[SD-16 years[range 11 - 75 and they were consisted with 15 males and 18 females. The causes of mitral disease in 33 patients were classified as follows: 19 cases[58% were degenerative, 9[27% were rheumatic, 3[9% were congenital and 2[6% were infectious. Carpentier`s functional classification was consisted with Class I 4 cases[12% , II 25 [76% and III 4 [12% . Surgical techniques included prosthetic annuloplasty in 32 cases[97% , leaflet resection in 16[48% , chorda shortening in 13[39% , chorda transfer in 9[27% , new chorda formation in 7[21% , commissurotomy in 7[21% , leaflet mobilization in 4[12% , chorda resection in 3[9% , papillary muscle splitting in 2[6% , cleft repair in 2[6% , leaflet patching in 1[3% and vegetation removal in 1[3% . Average number of mitral anatomical lesions per patient was 3.3 and We used average 3.0 procedures upon mitral valve apparatus per patient. Intraoperative transesophageal echocardiography was carried out in 27 patients[82% for providing an immediate and accurate assessment of the adequacy of the reconstruction before closure of the chest. Operative mortality was absent. The mean functional class[NYHA was 2.87 preoperative and improved to 1.03 postoperatively. Postoperative Doppler echocardiography showed much improvement from grade II MR[5 , grade III[5 , grade IV[21 to no MR[26 , only trace MR[3 , grade III MR[2 . Postoperative mean mitral valve area was 2.4$\pm$0.6cm2[range 1.5 - 4.0 . We conclude that cautiously evaluated mitral valve reconstruction is stable and predictable operation with minimal postoperative left ventricular dysfunction.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.11
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• pp.1077-1084
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• 2017

Camshaft engines designed for constant engine loads have been applied to existing marine diesel engines. However, due to environmental regulations, electro-hydraulic servo mechanisms, which have a loaddependent cylinder liner jacket water cooling system (LDCL-JWCS), have been recently developed to individually control the temperature of the cylinders depending on the engine load. In this system, the 3-way valve, which prevents low temperature corrosion by reducing the temperature difference between the upper and lower parts of the cylinder, has been employed, but the outlet mass flow of the existing valve is low. In this study, the design of the internal shape of the 3-way valve was performed by analyzing the effects of the design parameters of the valve shape on the performance (i.e., the outlet mass flow rate and temperature). The proposed model was verified by comparing its performance to that of existing marine diesel engine valves.