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레이저 프린터에 사용되는 폴리곤 미러 스캐너 모터 주위의 유동 해석을 통한 공력소음 저감
정연하(Yeonha Jung),장건희(Gunhee Jang),김명규(Myunggyu Kim),Yusuf Cinar 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.11
This paper calculates the air flow around the polygon mirror scanner motor of a laser printer operating at high speed by using a commercial tool. Simulation result is verified by measuring the velocity of air flow around the polygon mirror with a hot-wire anemometer. The frequency spectrum of the air flow around the polygon mirror match with that of aero-acoustic noise, and it confirms that significant amount of the discrete peaks and broadband of aero-acoustic noise are originated from the air flow around the polygon mirror. This paper proposes an air block to reduce the air flow around the polygon mirror, and it shows experimentally that the proposed air block reduces not only the air flow but also the discrete and broadband of aero-acoustic noise.
실도로 주행조건에 따른 자동변속기의 발열예측 모델 개발
정연하(Yeonha Jung),김민규(Minkyu Kim),양영철(Youngchul Yang),정인호(Inho Jung),구창모(Changmo Koo),이선호(Sunho Lee),류완식(Wansik Ryu) 한국자동차공학회 2023 한국자동차공학회 학술대회 및 전시회 Vol.2023 No.11
The automatic transmission has a mechanism that transmits the power of engine to the driving system of the vehicle. While power is transmitted, heat is generated by gear friction, bearing friction, clutch friction, and oil churning, which are internal parts of the automatic transmission. If the temperature rises inside the transmission, it may adversely affect performance and durability, as well as affect malfunctions such as electric sensors. So, it is necessary to cool the heat generated inside the transmission. In this paper, we developed a thermal prediction model in vehicle condition. The model was composed of the vehicle model, controller, powertrain, and cooling circuit of the vehicle. We measured the temperature at each position of the transmission according to the driving conditions and thermal model verified by comparing experiment results.
정연하(Yeonha Jung),김민규(Minkyu Kim),양영철(Youngchul Yang),배만용(Manyong Bae),정인호(Inho Jung),이민수(Minsu Lee),구세주,류완식(Wansik Ryu) 한국자동차공학회 2022 한국자동차공학회 학술대회 및 전시회 Vol.2022 No.11
The automatic transmission has a mechanism that transmits the power of engine to the driving system of the vehicle. During power transmission, heat is generated by gear friction, bearing friction, clutch friction, and oil churning, which are internal parts of the Automatic Transmission. If the temperature rises inside the transmission, it may adversely affect performance and durability, as well as affect malfunctions such as electric sensors. So, it is necessary to cool the heat generated inside the transmission. In this paper, we developed a simulation model that can predict transmission efficiency. The analysis result of the efficiency prediction model was applied as a heat source for the thermal prediction model. We measured the temperature at each position of the transmission according to the operating conditions and thermal model verified by comparing experiment results.
정연하(Yeonha Jung),우지환(Jihwan Woo),정인호(Inho Jung),류완식(Wansik Ryu),이희용(Heeyong Lee) 한국자동차공학회 2017 한국자동차공학회 학술대회 및 전시회 Vol.2017 No.11
The automatic transmission has a mechanism that transmits the power of engine to the driving system of the vehicle and it is operated by hydraulic pressure. Recently, reducing the power loss of automatic transmissions, which have a great effect on fuel efficiency, is an important issue. Many researchers were studied the reduction of power loss. The power losses in automatic transmissions are largely divided into oil pump losses, clutch drag torque losses, seal drag losses and gear churning losses. One of them, clutch drag loss accounts for more than 30% of total clutch losses. Previous research have been studied the factors that affect clutch drag torque, but drag torque was investigated mainly on uniaxial rotation in the clutch. In this study, we developed mathematical model which predicts drag torque depending on relative velocity. The drag torque is measured by the absolute speed change in the relative rotation of the input and output of the clutch for the verifying the mathematical model, experimentally. Also, we measured and analyzed the drag torque according to the factor by which, absolute rotating speed, ATF flow rate, and ATF temperature affecting the drag torque at the relative rotation.
자동변속기 클러치 마찰재 드래그토크의 수학적 모델 개발 및 시험 분석
우지환(JiHwan Woo),정연하(YeonHa Jung),류완식(WanSik Ryu),이희용(HeeYong Lee) 한국자동차공학회 2017 한국자동차공학회 부문종합 학술대회 Vol.2017 No.5
The clutch and brake of Automatic Transmission (AT) are used to shift. When the clutch is in disengaged condition, no power should be transmitted. The clutch is composed of disks and plates, and the fluid that performs lubrication is between disks and plates. When the engine operates, shearing stress generates because of fluid viscosity between disks and plates. Therefore, drag loss occurs. Many researchers have studied the characteristic of drag torque before, and the drag torque is affected by various design variables. In this study, relative velocity between disks and plates at operating speed is calculated with lever analysis. So we developed mathematical model which predicts drag torque depending on relative velocity. Also, we verified the result of mathematical model experimentally. And we measured the drag torque due to the clearance between disk and plate. Then, test result discussed and analyzed.
Reynolds 방정식과 Hagen-Poiseuille 방정식의 연성해석을 통한 재순환홀을 갖는 유체동압베어링의 해석
강치호(Chiho Kang),장건희(Gunhee Jang),정연하(Yeonha Jung) 한국소음진동공학회 2014 한국소음진동공학회 학술대회논문집 Vol.2014 No.10
This paper proposes a method to calculate pressure and flow of the fluid dynamic bearings (FDBs) with a recirculation channel (RC) by solving the Reynolds and the Hagen-Poiseuille equations at the same time. The Hagen-Poiseuille equation is one-dimensional equation which describes the flow in a circular pipe such as the RC. This research developed a finite element program to solve the Reynolds and the Hagen-Poiseuille equation together. The proposed method was applied to calculate the pressure and flow of the FDBs which are composed of grooved or plain journal and thrust bearings, and RC. To verify the proposed method, it also developed a finite volume model of the FDBs, and pressure and flow were calculated by the commercial CFD solver. They agree well with the pressure and flow calculated by the proposed method. Finally, this research investigated the characteristics of the FDBs due to the radius change of the RC.