배관 플랜지 벌림 전용 장비의 구조해석

곽효서(Kwak Hyoseo) 대한기계학회 2022 대한기계학회 춘추학술대회 Vol.2022 No.5

유한요소해석을 통한 밸브 잠금 장치 설계

곽효서 대한기계학회 2022 大韓機械學會論文集A Vol.46 No.12

Valve lockouts have been used to prevent safety accidents due to human error; however, conventional lockouts have problems of failure of the locking function and lack of durability. This study developed a new type of lock device with clamps to improve the clamping force. A structural analysis of the basic model was conducted to identify its problems, and the clamp groove shape was optimized using the response surface method to maximize the clamping force. A performance test of a prototype was conducted to examine the clamping force and verify the optimal model. The harm to human life due to human error is expected to be reduced using the developed lock device at plants, achieving economic saving and improvement in working efficiency. 전력, 가스, 석유 등을 생산하는 플랜트에서는 작동유를 제어하는 밸브를 사용하는데, 허가받지 않은 작업자의 밸브 오동작으로 인한 사고를 막기 위해 밸브 잠금 장치를 이용하고 있다. 기존의 체인-자물쇠 및 래칫 방식 마스터락 장치는 작동 환경에 최적화되어 있지 않아 내구성, 작업 효율성 및 안전성에 문제가 있다. 이에 본 연구에서는 기존 제품의 문제점을 해결하기 위해 클램프 타입 스테인리스 바디 소재의 밸브 잠금 장치를 개발하였다. 클램프을 적용하여 와이어의 접지력을 증가시켰으며, 플라스틱 바디의 내구성 향상을 위해 SUS304 소재를 적용하였다. 클램핑 하중 극대화를 위하여 구조해석을 통한 클램프의 그루부 형상을 최적화하였으며, 목표 값 만족 여부를 판단하기 위해 최적 모델의 시제품 제작 및 클램핑 하중 테스트를 수행하였다.

구조해석을 통한 Valve out tool의 Collet 설계

곽효서 한국기계기술학회 2022 한국기계기술학회지 Vol.24 No.5

The flange spreader has been used to withdraw gaskets and valves during butterfly valve maintenance. When using the conventional flange spreader, an excessive working space (pipe separation distance) appears, and the pipe and flange are damaged by the load. Also, the equipment can’t be operated safely when the pipe has eccentric fitting. To solve the problems, a valve easy out tool with collet was developed for safely fixing and spreading flange. By using Ansys Workbench 2021 R2, the structural analysis of the original collet was performed, and shape design of the collet was carried out to improve structural safety.

가공경화가 고려된 커먼레일 파이프의 피로해석

곽효서(H. S. Kwak),김철(C. Kim),김영호(Y. H. Kim),장효성(H. S. Jang),산세레이스(San Sereitish) 한국정밀공학회 2013 한국정밀공학회 학술발표대회 논문집 Vol.2013 No.5월

Design of port shape for reducing irregularity of oil pump

곽효서,김철 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.12

Internal gerotor pumps has been used commercially in automatic transmissions, fuel pump engines, and compressors. As the automobile industry has required high fuel efficiency and reduction of noise, studies of internal gerotor profiles to obtain high flow rates and low irregularity have been conducted. But flow rate depends on volume of pumping chamber rather than geometric shape, therefore only design of lobe shape influences greatly on flow rate but has the limitation to a significant reduction of irregularity. On the contrary, flow of working oil is stable and smooth by design of port shape, so that it can help reduction of irregularity. In this study, the gerotor (2-ellipse), having a higher flow rate than the existing geroters, was chosen as the optimal design, and a design of the port shape was performed to decrease irregularity greatly through Computational fluid dynamics (CFD) analysis considering ten design parameters. The effect of each geometric parameter on irregularity was investigated through analysis of Signal-to-noise (S-N) ratios. Based on the results, an oil pump assembling the optimal gerotor (2-ellipse) with a new improved port shape was developed and has resulted in a significant reduction of irregularity, maintaining high flow rate.

간 세침흡인 검사로 진단된 Hydatid Cyst의 세포학적 소견

곽효일 ( Hyo Il Kawk ),노종섭 ( Jong Sup Roh ),문형배 ( Hyung Bae Moon ) 대한임상검사과학회 1994 대한임상검사과학회지(KJCLS) Vol.26 No.1

밸브 락디바이스의 클램프 하중 향상을 위한 형상 설계

곽효서(Kwak Hyoseo),강남규(Gang NamGyu) 대한기계학회 2022 대한기계학회 춘추학술대회 Vol.2022 No.5

Design of Laminated Seal in Cryogenic Triple-Offset Butterfly Valve Used in LNG Marine Engine

곽효서,성한샘,김철 한국정밀공학회 2019 International Journal of Precision Engineering and Vol.20 No.2

A cryogenic triple-offset butterfly valve, which is installed in LNG marine engine, controls flow of liquid nitrogen (− 196 °C) to liquefy natural gas (− 163 °C). The existing seal has dual-layer structure composed of rubber and metal seals. The rubber seal is needed to be frequently replaced owing to its low durability, and elasticity of the metal seal decreases in the cryogenic environment, so that leakage of the nitrogen occurs. In order to offer a combination of compressible and resilient materials that form a strong sealing performance in the cryogenic environment (− 196 °C), a new type of seal was devised by laminating muti-layers (graphite and stainless steel). The airtightness of the laminated seal was estimated by comparing contact pressure that occurs on surface of the seal with working pressure. Effects of design parameters in relation to the laminated seal were analyzed to improve sealing performance, and after that a shape of laminated seal to improve operability and airtightness was suggested. Also, the proposed model obtained from FEA was verified through hydraulic and cryogenic leakage tests.

Optimal design of the gerotor (2-ellipses) for reducing maximum contact stress

곽효서,이성환,김철 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.12

The oil pump, which is used as lubricator of engines and auto transmission, supplies working oil to the rotating elements to prevent wear. The gerotor pump is used widely in the automobile industry. When wear occurs due to contact between an inner rotor and an outer rotor, the efficiency of the gerotor pump decreases rapidly, and elastic deformation from the contacts also causes vibration and noise. This paper reports the optimal design of a gerotor with a 2-ellipses combined lobe shape that reduces the maximum contact stress. An automatic program was developed to calculate Hertzian contact stress of the gerotor using the Matlab and the effect of the design parameter on the maximum contact stress was analyzed. In addition, the method of theoretical analysis for obtaining the contact stress was verified by performing the fluid-structural coupled analysis using the commercial software, Ansys, considering both the driving force of the inner rotor and the fluid pressure, which is generated by working oil.

타원 1-타원형 인벌루트-타원 2 로브 형상의 제로터 최적 설계

곽효서(Hyo Seo Kwak),이승환(Sheng Huan Li),김철(Chul Kim) 대한기계학회 2015 大韓機械學會論文集A Vol.39 No.12

제로터(Gerotor) 오일펌프는 구조가 간단하고 1 회전당 토출량이 많기 때문에 소형화에 유리하며, 자동차의 엔진 윤활유 공급원 및 자동 변속기의 유압원으로 널리 사용되고 있다. 최근 자동차 산업에서는 연비향상 및 소음저감이 가장 중요한 문제로 대두되는데, 내접형 기어펌프 측면에서는 제로터의 치형설계 및 포트형상 설계를 통하여 이를 대처하고 있다. 이에 본 논문에서는 유량맥동이 매우 작은 값을 가지도록 조합된(타원 1-타원형 인벌루트-타원 2) 외부로브 형상에 대하여 치형의 기구학적 조건을 만족하는 식을 유도하여 내부로브 형상을 창출하였으며, 이에 대한 첨점 및 루프가 발생하지 않는 설계인자 범위를 결정하였다. 또한 설계인자의 변화가 치형의 형상 및 성능인자(유량, 유량맥동)에 미치는 영향을 파악하여 최적의 치형을 구하고자 하였다. A gerotor can be manufactured in a miniature size because it has a high discharge per cycle and a simple structure. Gerotors are widely used for the lubrication oil of an engine and as the hydraulic source of an automatic transmission. Recently, improvements in fuel efficiency and noise reduction have come to the fore in the automobile industry, and it has been necessary for better fuel efficiency to continuously improve the flow rate and noise of internal gear pumps through the optimal design of the gerotor and port shape. In this study, gerotors were generated based on the equations derived for a lobe shape with multiple profiles (ellipse 1-elliptical involute-ellipse 2). The ranges of the design parameters were considered to prevent a cusp and loop. In addition, the optimal lobe shape was obtained by determining the influence of the lobe shape on the performances (flow rate, irregularity, etc.), according to the values of the design parameters.