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고재명(J. M. Ko),이용범(Y. B. Lee),한성건(S. K. HAN),김태석(T. S. Kim) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.11
In this research, the coiled type tube oil cooler employing in industry fields is composed of a steel shell and a coiled tube unit. The coil unit consists of 4 layers of concentric spirally coiled tubes. Each coil layer is fabricated by bending a straight copper tube into a spiral-coil of two turns. Oil and water are employed as testing fluids. The cold water entering the outermost turn flows along the spirally coiled tube, and flows out at the innermost turn. The hot oil enters the cooler at the side of the shell and flows radially across spiral tubes to the periphery. In this study, the heat transfer characteristics and the performance of a coiled tube oil cooler under cooling conditions are investigated. A mathematical model based upon the heat transfer equation is employed and calculated by using the numerical method to understand the cooler characteristics. The effects of various inlet conditions of working fluids flowing through the coiled type tube oil cooler are discussed.
이용범(Y. B. Lee),고재명(J. M. Ko),김태석(T. S. Kim) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.10
The intelligent(automation and manless) hydraulic excavator can be realized when the position sensor is equipped within hydraulic cylinder. But, during the time, the installation of position sensor was impossible because cylinder used the cushion at both ends and the broken problem of sensor is arisen under working when it is installed outside of hydraulic cylinder. In order to these problems, we developed high-reliable hydraulic cylinder using a new position detecting technology. As it were, firstly, seat type permanent magnets are installed on the partial load surface of hydraulic cylinder and outer wall is made by use of non magnetic stainless tube, and then the hall sensor detects the rod position of hydraulic cylinder. This technology improved the weak magnetic slope problem arisen when position control is performed, and also solved the electromagnetic noise problem according to increasing of amplification rate of magnetic sensor.
이용범(Y. B. Lee),고재명(J. M. Ko),한성건(S. K. Han),김정훈(J. H. Kim) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.10
The great impact is arisen by inertia at both ends which booms, arms, bucket, and hydraulic cylinders finish their stroke due to the joint structure of hydraulic excavator. This impact make fatigue of equipment and reduce the comfortable to ride in. This mechanical inertia energy is converted to fluid energy by cushion installed in hydraulic cylinder which induces high pressure(200~400% of commercial pressure) in a moment, and then the fluid energy again converted to heat energy through orifice. Therefore, the cushion technology of hydraulic cylinder has a great effect on operator's sensitivity(operator's comfortable to ride in) as well as protection for equipment damage by suppressing the inertia of hydraulic excavator. In this study, 3 hydraulic cylinders were used and installed different cushion ring and cushion plunger in them. And we studied optimal cushion pattern by analysis of change of cushion pressure and time according to velocity and pressure variations.
이용범(Y. B. Lee),고재명(J. M. Ko),김태석(T. S. Kim) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.11
The operation in excavators is somewhat lonely and helplessness due to the repeated working in a narrow space during a long time and operator is easily exposed to the poor circumstances as high noise, vibration, high/low temperature and dust. So it is getting harder to find out the operator of the machine. Moreover, operating fee of excavators is getting higher because of high oil (fuel and hydraulic fluid) price. Therefore, to improve the working circumstances and excavating efficiency, it is necessary to develop a remote control and automatic function of excavating operation. In order to develop a position detecting cylinder using for its automation, we installed a permanent magnet at regular intervals with switching N and S pole on the part of load surface of a hydraulic cylinder and obtained high output rate by detection of a hall sensor. From this, we solved problems like a weak magnetism level which is generated when we controlled a position of the cylinder and noise problem by increasing the amplification rate of magnetic sensor. At last, we developed a reliable position detecting technology of hydraulic cylinder for excavators.
원통다관 형 오일냉각기의 최적선정 및 도면 출력 프로그램 개발
이용범(Y. B. Lee),고재명(J. M. Ko),김태석(T. S. Kim) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.5
Shell & Tube type Oil Cooler is widely used for hydraulic presses, die casting machines, generation equipments, machine tools and construction heavy machinery. Temperature of oil in the hydraulic system changes viscosity and thickness of oil film. They have a bad effect to performance and lubrication of hydraulic machinery, so it is important to know exactly the heat exchanging efficiency of oil cooler for controlling oil temperature. But most Korean manufacturers do not have test equipment for oil cooler, so they cannot carry out the efficiency test of oil cooler and it is impossible to verify its performance. This paper includes information of construction of necessary utilities for oil cooler test and design and manufacture of test equipment. One can select the optimum product by obtaining performance data through tests of various kinds of oil coolers. And also the paper developed a program which can be easily used for design of 2D and 3D drawings of oil cooler.
이용범(Y. B. Lee),고재명(J. M. Ko),박종호(J. H. Park) 유공압건설기계학회 2008 드라이브·컨트롤 Vol.5 No.2
Hydraulic excavator consists of booms, arms, bucket, and cylinder. The cylinder make these structures moved and the cushion parts of cylinder in operation absorb the great impact which is stemmed from high velocity and pressure at cushion parts of cylinders. The cushion technology of cylinders has a great effect on the operator’s comfortable as well as protecting equipment from damage by suppressing the inertia of the hydraulic excavator. In this study, three hydraulic cylinders have different shapes of a cushion ring, respectively. we studied optimal cushion pattern by analyzing the change of cushion pressure and time, according to supply pressure and velocity variations.
원통다관식 열교환기의 압력 변화에 따른 설계 응력 연구
이용범(Y. B. Lee),한성건(S. G. Han),고재명(J. M. Ko) 유공압건설기계학회 2008 드라이브·컨트롤 Vol.5 No.2
Shell-and-tube type heat exchangers are generally classified with fixed tube-sheet and floating tube-sheet heat exchangers. In this paper, we employed the fixed tube-sheet heat exchangers. We theoretically investigated the safety evaluation of our shell-tube heat exchanger by axial, bending and equivalent stress of fill tubes, tube plates, channels and shell. Design pressure ranges were chosen pressure(0.6~2 ㎫) on tube side and 200 %(3 ㎫) of Maximum pressure on shell side for safety evaluation of heat exchangers. This research will be useful for fabrication of heat exchangers to prevent against damage hazard of heat exchangers in operation.
이용범(Y. B. Lee),한성건(S. K. Han),고재명(J. M. Ko) 한국동력기계공학회 2006 한국동력기계공학회 학술대회 논문집 Vol.- No.-
In this study, the heat transfer characteristics and the performance of a shell & tube oil cooler under cooling conditions are investigated. For performance test of oil cooler, we manufactured a test equipment which can heat oil up to the test temperature and supply it continuously to be tested object. This test equipment was composed of 300,000 Kcal/h steam boiler and 300,000 Kcal/h plate type heat exchanger, and this can do real time control the test conditions by the method which high temperature water heats the outlet cooled oil after test. For many different size oil coolers, by use of this equipment, we evaluated the heat exchange performance of oil coolers and pressure drop characteristics in side of oil and cooling water according to flow variation.