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"Hyo Seo Kwak"

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"Hyo Seo Kwak"

Articles
Design of Gerotor Oil Pump with Expanded Cardioid Lobe Shape to Reduce Noise
Min Cheol Lee, Hyo Seo Kwak, Hyeon Jong Kim, Chul Kim
J. Korean Soc. Precis. Eng. 2018;35(8):761-767.
Published online August 1, 2018
DOI: https://doi.org/10.7736/KSPE.2018.35.8.761
Gerotor oil pumps are widely used for the lubrication oil of an engine and the hydraulic source of an automatic transmission. Recently, improvements for the purposes of fuel efficiency and noise reduction have come to the forefront of the automobile industry, and it has become necessary to study the design of gerotors and ports. In this study, an expanded cardioid curve was developed, and an equation for a tooth profile with an expanded cardioid lobe shape has been suggested to reduce pump noise. The design was created using an automatic program; the program generated inner and outer rotor profiles and calculated performance parameters. Also, in order to decrease irregularity, CFD analyses were performed according to groove shapes in the exhaust port. Results showed the noise of the improved oil pump (the suggested gerotor [expanded cardioid] + the proposed port) was 5.44% lower than the existing oil pump (the existing gerotor [2-ellipse] + basic port).
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Design of Tip Clearance in the D.D.I. Process to Manufacture Pressure Vessel
Hyo Seo Kwak, Gun Young Park, Chul Kim
J. Korean Soc. Precis. Eng. 2018;35(7):715-720.
Published online July 1, 2018
DOI: https://doi.org/10.7736/KSPE.2018.35.7.715
The liner of CNG pressure vessel was manufactured using a deep drawing and ironing (D.D.I.) process with a single punch. Tip clearance between billet and die suggested in the actual field has been widely used to reduce forming load and to improve die life. However, the analysis and design of tip clearance is necessary for the third stage of forming defect. In this study, the tip clearance of the third stage was determined to limit the ratio of reduction of cross-sectional area based on theoretical analysis. The proposed tip clearance was verified via finite element analysis. In addition, the simulation technique was established by comparing the forming load based on theoretical calculation with the load determined via FEM.
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A Study on the Vibration Reduction of Turbine Rotor through Advanced Flexible Packing Rings
Hyeon Jong Kim, Hyo Seo Kwak, Han Saem Sung, Chang Ryeol Lee, Chul Kim
J. Korean Soc. Precis. Eng. 2018;35(7):681-687.
Published online July 1, 2018
DOI: https://doi.org/10.7736/KSPE.2018.35.7.681
Steam turbines of thermal power plants are installed in such a way that packing ring surrounds the entire turbine rotors in order to reduce the amount lost due to a leak of steam and to improve performance. However, the conventional packing ring cannot affect positively fluid velocity of the direction of steam, so it does not have the power to reduce vibration of the rotor. In this research, a study was conducted to reduce it by lowering the rotational speed of steam in the rotor. Anti-swirl teeth which changes rotational speed of steam into axial speed of it, designed in front of the conventional packing rings, and their numbers, twist angles. The characteristics of the rotor and the anti-swirl teeth were chosen as design factors to reduce vibration of the rotor. Through the finite element, the improved packing ring designed with the optimal anti-swirl teeth was developed.
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Optimal Design of Gerotor (Ellipse1-Elliptical Involute-Ellipse2 Combined Lobe Shape) for Improving Fuel Efficiency and Reducing Noise
Hyo Seo Kwak, Sheng Huan Li, Chul Kim
J. Korean Soc. Precis. Eng. 2016;33(11):927-935.
Published online November 1, 2016
A gerotor is suitable for miniature manufacturing because it has a high discharge per cycle and a simple structure, while also being widely used as lubrication oil of engines and the hydraulic source of automatic transmission. In the automobile industry, it has been necessary to continuously improve the flow rate and noise of internal gear pumps for better fuel efficiency through optimal gerotor design. In this study, to obtain an optimal gerotor with an ellipse-elliptical involute-ellipse combined lobe shape, an automatic program was developed for calculating performance parameters and drawing a gerotor profile. An oil pump was assembled with the optimal gerotor together with the port used at the actual field and CFD analysis was performed on this assembly using Ansys-CFX. A performance test for the oil pump was carried out and showed good agreement with the results obtained from the theoretical analysis and the CFD analysis.
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Development of an Advanced Oil Deflector Used in Thermoelectric Power Plant
Yong Hoon Choi, Hyo Seo Kwak, Chang Ryeol Lee, Chul Kim
J. Korean Soc. Precis. Eng. 2016;33(8):661-668.
Published online August 1, 2016
Oil deflector prevents oil leakage that occurs in thermoelectric power plant at operating lubricant facilities. Vibration of rotating rotor-induced wear of aluminum tooth in existing oil deflector leads to oil leakage as well as life shortening of the tooth. In this study, an advanced oil deflector was developed for shock absorption and prevention of wear by decreasing clearance (from 0.5 mm to 0.2 mm) between rotor and tooth to minimize oil leakage, and by replacing 2 aluminum teeth in outmost of the oil deflector with hi-performance seal made of engineering plastic. The CFD results were compared between advanced vs. existing oil deflector to determine the amount of oil loss. Structural safety was verified through impact analyses according to the three kinds of engineering plastics, considering cost efficiency, and optimal material of hi-performance seal was chosen.
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Performance Improvement of Oil Pump by Design of Gerotor (Combined Profile ? Two Ellipses) and Port
Hyo Seo Kwak, Sheng Huan Li, Chul Kim
J. Korean Soc. Precis. Eng. 2016;33(3):207-216.
Published online March 1, 2016
A gerotor is suitable for miniature manufacturing because it has high discharge per 1 cycle and a simple structure, while also being widely used for lubrication oil of engines and as a hydraulic source of automatic transmission. In the automobile industry, improvements in fuel efficiency and noise reduction have recently come to the fore. It has also been necessary to continuously improve the flow rate and noise of internal gear pumps for better fuel efficiency through optimal gerotor and port shape design. In this study, to develop an optimal gerotor with a new lobe shape, 2-ellipses-combined, the equation of the lobe shape was derived, and CFD analysis results were compared for 2-ellipses with those of the previous gerotors (3-ellipses and ellipse1-involuteellipse2). A performance test for the oil pump with the optimal rotor (2-ellipses) was carried out and showed good agreement with the results obtained from CFD analysis.
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Progressive Process Design for Delta Sash in Vehicles
Young Jun Ko, Hyo Seo Kwak, Jun Ho Bae, Chul Kim
J. Korean Soc. Precis. Eng. 2014;31(12):1161-1170.
Published online December 1, 2014
Delta sash is an important part of automobile door, which has the functions of supporting and guiding seesaw of car’s window, preventing dust and air from outside. In previous manufacturing process, each part of the delta sash was independently formed by tandem processes, and rubber is bonded to steel by poisonous glue. So, the previous processes, including roll forming process and toxic gases, had low production rate and high failure rate. In this study, progressive process design of the delta sash was proposed in order to increase productivity and high utilization of the materials. And instead of the poisonous glue used for adhesion of rubber in the previous tandem process, embossing and piercing processes were designed in the new guide to help the rubber to adhere well to steel. And the optimal piercing distance was designed to ensure structural safety, and prototypes were manufactured for verifying reliability of the processes.
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