$Annubar^{(R)}$형 차압유량계 형상 개선에 따른 유량 특성 연구

오대산,이충훈,Oh, Dae-San,Lee, Choong-Hoon 한국생산제조학회 2010 한국생산제조학회지 Vol.26 No.2

The inner structure of the triangular separate bar (TSB) was improved to enhance the productivity of the TSB flow meter by simplifying the machining process for making the flow meter. The cross section of upstream and downstream pressure chamber in the TSB was changed from triangle to circle, which make it possible to substitute the wire cutting by drilling in the process of machining the pressure chamber. The flow rate characteristics of the flow meters was calibrated with a laminar flow meter. Six kinds of flow meters whose diameters of pressure tap for measuring pressure of both upsteam and downstream pressure chamber were different one another were made. The effects of the pressure tap diameter on the flow rate characteristics of the TSB flow meter was little. The mass flow rate characteristics of the flow meters with increasing a non-dimensional parameter which includes the gas temperature, exhaust gas pressure and differential pressure at the flow meters and atmospheric pressure shows nearly linear relationship with a correlation coefficient of R=0.998.

AnnubarⓇ형 차압유량계 형상 개선에 따른 유량 특성 연구

오대산,이충훈 한국생산제조학회 2010 한국생산제조학회지 Vol.19 No.2

The inner structure of the triangular separate bar (TSB) was improved to enhance the productivity of the TSB flow meter by simplifying the machining process for making the flow meter. The cross section of upstream and downstream pressure chamber in the TSB was changed from triangle to circle, which make it possible to substitute the wire cutting by drilling in the process of machining the pressure chamber. The flow rate characteristics of the flow meters was calibrated with a laminar flow meter. Six kinds of flow meters whose diameters of pressure tap for measuring pressure of both upsteam and downstream pressure chamber were different one another were made. The effects of the pressure tap diameter on the flow rate characteristics of the TSB flow meter was little. The mass flow rate characteristics of the flow meters with increasing a non-dimensional parameter which includes the gas temperature, exhaust gas pressure and differential pressure at the flow meters and atmospheric pressure shows nearly linear relationship with a correlation coefficient of R=0.998.

Development of a new system for measuring the swirl ratio of an engine cylinder head under an unsteady flow condition

오대산,이충훈 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.2

A new impulse-type swirl meter that measures the swirl ratio (R s ) and flow coefficient (C fmean ) during an intake air process for the intake port of an engine cylinder head under unsteady flow conditions was developed. The camshaft of the cylinder head was directly rotated by a step motor, allowing the valve lift to be adjusted automatically with the camshaft profile in the newly developed swirl measurement system. The measurements of the swirl ratio and flow coefficient were automated using a FPGA-DAQ board and a computer. The rotational speeds of the camshaft were held constant at steps of 90, 120, 150, 180 and 210 rpm during the measurement. As the camshaft rotation speed increased, the values of R s tended to decrease while those of C fmean tended to increase, implying that R s and C fmeandepend on the engine speed. These results should be considered in the design of an intake port. With the newly developed swirl measurement system, it is possible to measure R s and C fmean repeatedly in a very short time. The repetitive measurement results of R s and C fmean were statistically processed. Through an uncertainty analysis, the values of the upper and lower bounds of R s and C fmean can be calculated for each camshaft rotation speed.

군 지휘차량의 전자파 장해 개선방안 연구

오대산,서석호,정규황,김종민,홍준식 한국기계기술학회 2020 한국기계기술학회 학술대회논문집 Vol.2020 No.07

군용 궤도차량 디젤엔진의 커넥팅 로드 볼트 파손 검토를 통한 고장원인분석

오대산,김지훈,서석호 한국산학기술학회 2020 한국산학기술학회논문지 Vol.21 No.7

군용 궤도차량은 일반 차량보다 더 가혹한 주행조건과 기후환경에서 운용되며, 이러한 환경에서 사용되기 위하여 적용되는 부품들은 고도의 신뢰성과 내구성이 요구된다. 특히 디젤엔진은 군용 궤도차량의 주 동력발생장치로써, 차량 주행 간 고장이 발생할 시에 대형사고로 이어질 가능성이 높다. 따라서 엔진의 고장 및 파손원인을 분석하는 것은 추후 발생할 수 있는 유사한 사례를 사전에 예방할 수 있는 중요한 과정이라고 할 수 있다. 본 연구에서는 군용 궤도차량 주행 간 발생된 고장 엔진에 대하여 분해검사와 경도 측정, 파단면 분석 등의 파손원인검토를 통하여 엔진 파손 메커니즘을 규명하였다. 파손 엔진에 대한 분해검사를 통하여 4번 커넥팅 로드에서 볼트가 분리되어 이탈된 것이 확인되었다. 또한 4번 커넥팅 로드 볼트의 경도 측정 결과는 규격에 적합하였으며, 파손된 볼트의 파단면 분석을 통하여 볼트는 연성파괴 되었다는 것을 알 수 있었다. 이와 같은 분석 결과를 바탕으로 이번에 발생된 군용 궤도차량 디젤엔진의 파손은 최초 4번 커넥팅 로드 볼트의 풀림으로 인한 이탈과 파손이 연쇄적인 손상으로 이어져 발생되었던 것으로 판단되었다. 본 연구에서 수행한 엔진 고장원인분석 결과는 향후 타 장비의 유사한 엔진 고장 및 파손원인분석 연구에 참고사례 및 유용한 자료가 될 수 있을 것으로 사료된다. Tracked military vehicles are operated under harsher conditions and climates than ordinary vehicles, and the components require high degrees of reliability and durability. A diesel engine is the main power generator, and when the vehicle breaks down, there is a high possibility of causing a large-scale accident. Therefore, analyzing the cause of engine failure can be important for preventing similar cases that may occur. In this study, we clarified the mechanism of engine failure according to an overhaul test, hardness measurement, and an analysis of the fracture surface. The overhaul test confirmed that a bolt was separated from the connecting rod (number 4). In addition, the hardness measurement results of the connecting rod bolt conformed to the standard, and it was found that the bolt fracture was ductile fracture through an analysis of the fracture surface. Based on the results, it was concluded that damage to a diesel engine of a tracked military vehicle was caused by separating and damage caused by loosening of the connecting rod bolts, resulting in cascading damage. The results of the study could be used as reference examples and could be useful for another study on engine failure analysis.

밸브 양정의 연속 변화에 의한 준정상 유동 조건에서의엔진 실린더헤드 유량계수 특성

오대산,이충훈 한국안전학회 2010 한국안전학회지 Vol.25 No.6

Flow Coefficients of intake port in an engine cylinder head were measured by a newly designed flow rig. In measuring the flow coefficient with traditional method, the valve lift was manually varied by technician with adjusting a micrometer which is directly connected to the intake valve of the cylinder head. The cam shaft of the cylinder head is directly rotated by a step motor and the valve lift was automatically varied with cam shaft profile in the newly designed flow rig. The measurement of the flow coefficient was automated by rotating the cam shaft with the step motor. Automatic measurement of the flow coefficient could be safely measured by separating a technician from the noise and vibration of the traditional flow rig. Also, the automatic measurement of the flow coefficient reduce the measurement time and provide meaningful statistical data

엔진 성능검사 공정 간 형광염료 적용을 통한 품질확보방안

오대산,정규황,서석호,박창하 한국품질경영학회 2019 한국품질경영학회 학술대회 Vol.2019 No.-

엔진은 장갑차, 전차, 자주포 등의 전투 궤도장비에서 가장 중요한 역할을 하는 동력발생장치라고 할 수 있다. 이러한 엔진 내부를 순환하는 윤활유인 엔진오일(Engine oil)은 동작부품의 마찰손실을 줄여 수명을 연장하고 내구성을 향상시켜주는 주요한 기능을 하기 때문에 엔진오일의 누유는 엔진고장 발생의 주요 원인이 될 수 있다. 성능검사 시 엔진오일의 누유현상을 식별하려면 빛을 비추어 육안으로 빛의 반사정도나 얼룩을 확인하여야 하는데, 빛의 입사각도 및 주변 환경에 따라 식별이 어려워질 수 있다. 따라서 본 연구에서는 형광염료가 주입된 엔진 오일을 통하여 누유를 가시화하고 식별력을 증대시켜 엔진의 생산품질을 향상시키고자 하였다. 엔진 성능검사 공정 간 형광염료의 적용가능 여부를 검토하기 위하여 기존 엔진오일과 형광염료가 첨가된 엔진 오일의 비교분석과 형광염료가 주입된 실제 엔진 성능시험를 통한 유효성 평가를 수행하였다. 그 결과를 바탕으로 본 개선방안에 대한 적용방법을 강구하였다. 정량주입, 혼용제한, 청정처리 등을 고려하여 형광염료 자동주입 장치를 이용한 엔진오일 주입 공정 개선방안을 검토하였다. 그리고 엔진 성능검사 중 또는 성능검사 후, 누유확인 시에 단순히 육안으로 확인하는 것이 아니라 자외선을 조사하며 누유 여부를 확인하도록 하는 방법을 제시하였다. 검사 중 누유 발생 시에는 엔진오일에 주입된 형광염료가 자외선에 의하여 발광함으로써 가시화 및 식별이 용이하며 누유에 대한 검출력을 매우 증대시킬 수 있다고 사료된다. 이와 같이 엔진오일 누유에 대한 검출력을 증대하기 위하여 형광염료를 적용함으로써 엔진에 대한 품질확보와 군신뢰도 향상이 기대된다. 또한 엔진 생산업체의 품질관리 능력 향상에 의한 품질 비용의 최소화를 시킬 수 있다고 사료된다.

기체 온도가 Annubar<SUP>Ⓡ</SUP>형 차압유량계 유량 특성에 미치는 연구

오대산(Daesan Oh),박동선(Dongsun Park),이충훈(Choonghoon Lee) 한국자동차공학회 2010 한국자동차공학회 부문종합 학술대회 Vol.2010 No.5

A shape improved flow meter which has a similar structure of Annubar<SUP>®</SUP> type flow meter was designed and its flow rate characteristics were evaluated by calibrating the flow rate of the flow meters. The supplying air temperature was maintained constantly by controlling power supply to electric heater during the calibration. Two kinds of differential pressure measured at the flow meter were used in calculating the H parameter which represents characteristics of the flow meter. The H parameter was calculated based on the differential pressure which is the difference between upstream and downstream pressure tabs of the flow meters. The other parameter was calculated based on the differential pressure which is the difference between upstream pressure of the flow meter and static pressure ,that is, the dynamic pressure of the flow in the flow meter. Relationship curves between the non-dimensional parameters and mass flow rate at the flow meter were obtained. The curve based on the differential pressure obtained from the difference between up and down stream pressure tabs show different gradients with varying the controlled air temperature. However, the other curve based on the dynamic pressure shows the same gradient with varying the air temperature.

디젤 엔진 연료 분사 타이밍 구간에서의 흡기 포트 스월비 1D 컴퓨터 시뮬레이션

오대산 ( Dae San Oh ),이충훈 ( Choong Hoon Lee ) 한국분무공학회 2021 한국액체미립화학회지 Vol.26 No.2

This study was performed to calculate the swirl ratio of a diesel engine intake port by a 1D computer simulation under actual engine operating conditions. The swirl ratio of the intake port was simulated according to the change of the engine speed during the operation of the motoring without fuel injection. The swirl ratio of the intake port was simulated according to changes in the crank angle during the four-cycle operation of intake, compression, expansion and exhaust. The swirl ratio represented by the three regions of the piston, center and squish was simulated. Among the three regions, the piston-region swirl ratio is important for effective air-fuel mixing in the engine cylinder. In particular, it was confirmed during the simulation that the piston swirl ratio before and after the compression top dead center (TDC) point when fuel is injected in the DI diesel engine can have a significant effect on the mixing of air and fuel. It was desirable to set the average piston swirl ratio over a crank angle section before and after compression TDC as the representative swirl ratio of the cylinder head intake port according to the change of the engine speed.

Annubar<SUP>Ⓡ</SUP>형 차압유량계 형상 개선에 따른 유량 특성 연구

오대산(Daesan Oh),이충훈(Choonghoon Lee) 한국생산제조학회 2010 한국생산제조학회지 Vol.19 No.2

The inner structure of the triangular separate bar (TSB) was improved to enhance the productivity of the TSB flow meter by simplifying the machining process for making the flow meter. The cross section of upstream and downstream pressure chamber in the TSB was changed from triangle to circle, which make it possible to substitute the wire cutting by drilling in the process of machining the pressure chamber. The flow rate characteristics of the flow meters was calibrated with a laminar flow meter. Six kinds of flow meters whose diameters of pressure tap for measuring pressure of both upsteam and downstream pressure chamber were different one another were made. The effects of the pressure tap diameter on the flow rate characteristics of the TSB flow meter was little. The mass flow rate characteristics of the flow meters with increasing a non-dimensional parameter which includes the gas temperature, exhaust gas pressure and differential pressure at the flow meters and atmospheric pressure shows nearly linear relationship with a correlation coefficient of R=0.998.