• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.286-289
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• 2008

Wind turbine industry is booming and spending a lot on research for improving the performance of its present machines and increasing their capacity. Wind turbine requires service life of about 20 years and each components of wind turbine requires high durability, because installation and maintenance costs are more expensive than generated electricity by wind-turbine. So the design of wind turbine must be verified in various condition before production step. For this work, high reliability model for analysis is required. Drivetrain model is modeled by multibody dynamic modeling method. The model constituted with rotor blades, hub, main shaft, gear box, high speed shaft and generator. Natural frequency and torsional stiffness of drivetrain are calculated and analyzed.

• Transactions of the Korean Society of Automotive Engineers
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• v.1 no.1
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• pp.80-89
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• 1993

Performance simulation for a Spark Ignition Wankel rotary Engine is presented in this paper. The volume of chamber at each eccentric shaft angle is evaluated by using geometric models of housing and rotor. A thermodynamic model which includes the first law of thermodynamics, combustion and convective heat transfer from chamber contents to surroundings is imployed. A thermochemical equilibrium model which considers 10 species(CO, $CO_2$, $O_2$, $H_2$, $H_2O$, OH, O, NO, $N_2$) in the burned gas region, is also employed. Four processes of gas exchange, compression, combustion and expansion are considered and the pressure, temperature and composition of chamber gas at each eccentric shaft angle in each process are computed in this performance simulation. This performance simulation must be useful for optimal design of Spark Ignition Wankel Rotray Engine with parametric study for various design parameters and operating conditions.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.10a
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• pp.583-586
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• 2012

Wind turbine industry is booming and spending a lot on research for improving the performance of its present machines and increasing their capacity. Wind turbine requires service life of about 20 years and each canponents of wind turbine requires high durability, because installation and maintenance costs are more expensive than generated electricity by wind-turbine. So the design of wind turbine must be verified in various condition before production step. For this work, high reliability model for analysis is required. Drivetrain model is modeled by multibody dynamic modeling method. The model constituted with rotor blades, hub, main shaft, gear box, high speed shaft and generator. Natural frequency and torsional stiffness of drivetrain are calculated and analyzed.

• Journal of KSNVE
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• v.5 no.1
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• pp.49-57
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• 1995

An electronic circuit device is developed such that the displacement between an electromagnet and a moving target can be estimated from the coil current measurement, and then applied to an active magnetic bearing system. In order to levitate the shaft without using displacement sensor the stable control gains are obtained from the linearized model which includes the gap estimation circuit. Experimental results show that the shaft, by the estimated gap feedback, can be levitated within $\pm$6 ${\mu}m$ positioning error.

• The Journal of Engineering Geology
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• v.23 no.3
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• pp.227-234
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• 2013

The vertical shaft of a selective intake structure, which is constructed in a large reservoir, is required to be impermeable and to employ a grouting technology to prevent water inflow from the reservoir or surrounding ground. In this study, groundwater inflow is estimated using a numerical model for two cases (i.e., grouting or non-grouting cases at the exterior of a vertical shaft) and compared with data measured during an excavation at the construction site of a selective intake structure in the Soyang reservoir, Korea. Groundwater inflow is estimated to range from 444 to 754 $m^3/d$ in the case of non-grouting and from 58 to 95 $m^3/d$ in the case of grouting. The groundwater inflow measured in a vertical shaft, which ranges from 30 to 100 $m^3/d$, is similar to the simulated amount. It is recommended that before the excavation of a shaft, water inflow is estimated using a numerical model and a grouting test to ensure excavation stability and improve excavation efficiency.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.24 no.8
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• pp.583-591
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• 2014

The mathematical modeling on the free vibration and stability of a multi-stepped shaft of turbo compressor is performed in this study. The multi-stepped shaft is modeled as a non-uniform Timoshenko beam supported by anisotropic bearings. It is assumed that the shaft is spinning with constant speed about its longitudinal axis and subjected to a conservative axial force induced by front and rear impellers attached to the shaft. The structural model incorporates non-classical features such as transverse shear and rotary inertia. A structural coupling between vertical and lateral motions is induced by Coriolis acceleration terms. The governing equations are derived via Hamilton's variational principle and the equations are transformed to the standard form of an eigenvalue problem. The implications of combined gyroscopic effect, conservative axial force, bearing stiffness and damping are revealed and a number of pertinent conclusions are outlined. In this study analytical results are compared with those from ANSYS finite element analysis and experimental modal testing.

• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.1
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• pp.148-156
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• 2000

For the in-line three cylinder engine whose crankshaft has a phase of 120 degrees, the total sum of unbalanced inertia forces occurring in each cylinder will be counterbalanced among three cylinders. However, parts of inertia forces generated at the No.1 and No.3 cylinders will cause a primary moment about the No.2 cylinder. In order to eliminate this out-of-balance moment, a single balance shaft has been attached to the cylinder block so that the engine durability and riding comfort may be further improved. Accordingly, the forced vibration analysis of the in-line three cylinder engine must be implemented to meet the required targets at an early design stage. In this paper, a method to reduce noise and vibration in the 800cc, in-line three cylinder LPG engine is suggested using the multibody dynamic simulation. The static and dynamic balances of the in-line three cylinder engine are investigated analytically. The multibody dynamic model of the in-line three cylinder engine is developed where the inertia properties of connecting rod, crankshaft, and balance shaft are extracted from their FE-models. The combustion pressure within the No.1 cylinder in three significant operating conditions(1500rpm-full load, 4000rpm-full load and 7000rpm-no load)is measured from the actual tests to excite the engine. The vibration velocities at three engine mounts with and without balance shaft are evaluated through the forced vibration analysis. Obviously, it is shown that the vibration of the in-line three cylinder engine with balance shaft is reduced to the acceptable level .

• Journal of the Society of Naval Architects of Korea
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• v.56 no.2
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• pp.168-174
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• 2019

In order to investigate Propeller Open Water (POW) characteristics for the high-speed propeller in Large Cavitation Tunnel (LCT), the high-capacity inclined-shaft dynamometer was designed and manufactured. Its measuring capacities of thrust and torque are ${\pm}2200N$ and ${\pm}120N-m$, respectively. The driving motor is directly connected to the propeller shaft. Inclined angle of the propeller shaft can be adjusted up to ${\pm}10^{\circ}$. As the pressure inside LCT can be adjusted in the range of 0.1~3.0bar, we can carry out the POW test at high Reynolds number (above $1.0{\times}10^6$) without propeller cavitation and the cavitation test in uniform flow. After the new dynamometer setup in LCT, the Reynolds number variation test and propeller open-water test were conducted at the inclined angle of $0^{\circ}$ and $6^{\circ}$. The present POW results of the new dynamometer are compared with those of the existing high-capacity dynamometer in LCT and of the dynamometer in the towing-tank. Through systematic model tests and comparison with their results, the performance of the new inclined-shaft dynamometer was verified. It is thought the POW test for the high-speed propeller should be better conducted at high Reynolds number.

• Journal of the Korea Convergence Society
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• v.13 no.4
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• pp.307-313
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• 2022

The importance of engine vibration reduction is increasing as the vehicle interior noise becomes more serious due to higher output and lighten weight trends. Recently, the balance shaft attachment has been proposed as a representative method for the engine vibration reduction. The balance shaft is a device that cancels the vibrations generated in the reciprocating motion of the piston and the conrod by using an arbitrary eccentric mass, and can improve fuel efficiency and ride comfort at the same time. This paper proposes the unbalance amount and shape of the balance shaft to induce and offset the inertia force generated by the engine structure. The proposed two-shaped balance shaft was implemented as an ADAMS multi-body dynamics model, and the reduction of the inertial force in the actual behavior was confirmed through dynamic simulation.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.6
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• pp.914-921
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• 2022

The International Maritime Organization (IMO) has set a goal of reducing ship's carbon dioxide emissions by 70% and greenhouse gas emissions by 50% by 2050 compared to 2008. Shipowners and shipyards are promoting various R&D activities such as LNG propulsion, ammonia propulsion, electric propulsion, CO₂ capture, and shaft generators as a way to satisfy this problem. The dual shaft generator has the advantage that it can be directly applied to an existing ship through remodeling. In this paper, the total fuel reduction rate that can be obtained by applying the shaft generator to the existing ship was verified through simulation. For this purpose, the size of the medium-sized ship was defined, and the governor, diesel engine, propeller, torque switch, generator for shaft generator, propulsion motor for shaft generator, and ship model were modeled and simulated.