• Journal of the Korean Institute of Gas
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• v.26 no.2
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• pp.21-26
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• 2022

Since the four-wheel drive transmits the driving force to all four wheels, the traction with the road surface increases, thereby increasing the driving force. However, it has the disadvantage of lowering fuel efficiency. Therefore, four-wheel drive is commonly used as a method of converting to optional four-wheel drive when necessary while driving in two-wheel drive. This selective four-wheel drive converts the driving force by mechanically changing the electric signal sent by the driver in the transfer case. In this study, in order to mechanically change the electrical signal, a reducer is applied to the motor to increase the torque to perform the function. Therefore, in this study, a reduction mechanism applicable to the motor inside the transfer case applied to convert the drive is derived, and the reduction ratio applying the planetary gear type is optimized accordingly. And based on the derived reduction ratio, two sets of planetary gears using a ring gear in common were applied to develop a planetary gear tooth type in which the input shaft and output shaft are decelerated in the same phase. Optimization design was carried out.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.1303-1304
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• 2011

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.8
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• pp.1527-1533
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• 2002

When a mechanism transfers a motion to an intersected shaft, a cylindrical cam mechanism may be the best choice among the mechanisms. The cylindrical cam with a roller follower provides to transfer the motions to the intersect shafts simply without other connecting equipments of the intersect shafts. Typical example may be a roller-gear-cam mechanism. But the shape of the cam must be exactly defined in order to satisfy the conditions for the prescribed motion of the follower. This paper proposes a new method for the shape design of the cylindrical cams and also a CAD program is developed by using the proposed method. The relative velocity method calculates the relative velocity of the follower versus the cam at a center of roller, and then determines a contact point by using the geometric relationships and the kinematic constraints. The constraint used in the relative velocity method is that the relative velocity must be parallel to a common tangent line at the contact point of two independent bodies, i. e. the cam and the follower. Then, the shape of the cam is defined by the coordinate transformation of the trace of the contact points. Finally, this paper presents an example in order to prove the accuracy of the proposed methods in this paper and the application of the CAD program"CamDesign".

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.5
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• pp.719-726
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• 1997

The proportional pressure control valve having versatile functions and higher performance is an essential conponent in the open loop controlled rear wheel steering gear of the four wheel steering system in a passenger car. In this study, the authors suggest a new type of load pressure feedback mechanism which can make it easy to change the range of controlled pressure without changing the capacity of solenoid. The concept of suggested mechanism, composed of the pressure chamber with throttles in series, was described. The mathematical model was derived from the rear wheel steering gear consisting of a valve and a cylinder for the purpose of analyzing the valve characteristics. And the programme for computing the characteristic of the valve was developed. Experiments were performed to confirm the performance of the valve and computations were carried out to ascertain the usefulness of the developed programme. The results from computations fairly coincide with those from experiments. And the results from experiments and computations show that the performance of new valve was as good as that of the already developed one and the new valve has advantages such as the easiness of changing the range of controlled pressure and the decrease of power loss at neutral position without the decline of performance.

• Journal of Biosystems Engineering
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• v.18 no.3
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• pp.230-238
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• 1993

The parte(I) of this paper deals with the motion analysis of a gear type high speed planting mechanism of rice transplanters. Following that this part(II) contains force analysis of the mechanism. Forces and moments acting on the mechanism were determined analytically and computer coded for the simulation of them on any IBM PC compatiable machines. The simulation program developed in this study can be used as a design tool and also for a sensitivity analysis.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.189-195
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• 2003

This paper represents an identification procedure for leading mechanism of a car A/V system which is composed of a DC motor and a set of plastic gears. In addition, we studied dominant noise source of rattle noise generated by external forced vibration as a car drives. we made a dynamometer to produce stationary operation on loading mechanism of A/V system because noise generated by actual loading mechanism is non-stationary signal. operating the dynamometer setup at various motor speeds, sound pressure spectra are measured and the results are analyzed. its dominant noise source is also identified by using a sound Intensity technique. we made use of multi-dimensional spectral analysis to rind a dominant rattle noise. this method is so useful to eliminate coherence between vibration sources and helps us obtain coherent output spectrum of individual vibration source which make a rattle noise.

• International Journal of Automotive Technology
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• v.7 no.3
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• pp.295-301
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• 2006

A new combustion method of high compression ratio SI engine was studied and proposed in order to achieve high thermal efficiency, comparable to that of CI engine. Compression ratio of SI engine is generally restricted by the knocking phenomena. A combustion chamber profile and a cranking mechanism were studied to avoid knocking with high compression ratio. Because reducing the end-gas temperature will suppress knocking, a combustion chamber was considered to have a wide surface at the end-gas region. However, wide surface will lead to large heat loss, which may cancel the gain of higher compression ratio operation. Thereby, a special cranking mechanism was adapted which allowed the piston to move rapidly near TDC. Numerical simulations were performed to optimize the cranking mechanism for achieving high thermal efficiency. An elliptic gear system and a leaf-shape gear system were employed in numerical simulations. Livengood-Wu integral, which is widely used to judge knocking occurrence, was calculated to verify the effect for the new concept. As a result, this concept can be operated at compression ratio of fourteen using a regular gasoline. A new single cylinder engine with compression ratio of twelve and TGV(Tumble Generation Valve) to enhance the turbulence and combustion speed was designed and built for proving its performance. The test results verified the predictions. Thermal efficiency was improve over 10% with compression ratio of twelve compared to an original engine with compression ratio of ten when strong turbulence was generated using TGV, leading to a fast combustion speed and reduced heat loss.

• International journal of advanced smart convergence
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• v.9 no.3
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• pp.199-206
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• 2020

A wheelchair is an essential rehabilitation assistant device for the movement of paraplegia patients and generally paralyzed patients who cannot walk normally. In particular, the applicability of the manual/motorized wheelchair is gradually increasing. Until now, decelerators using belt, chain and worm gears, etc have been widely used. However, a decelerator takes a large space although it is a simple device and thus is not ideal for the driving part of manual/motorized wheelchair. For these reasons, in this study we developed a driving part producing a large driving force through a decelerator using planetary gears rather than conventional worm gear-based decelerator. We designed the tooth profile of the planetary gears for decelerator using Kisssoft program, In addition, we designed the driving part so as to apply it to the wheels of conventional wheelchairs, and then optimized the mechanism for the principles of manual/motorized transposition of the driving part and the operational principles. Based on the results of this study, we finally designed and manufactured a driving part for wheelchair decelerator in the form of planetary gears with 1 sun gear, 2 planetary gears and 1 ring gear.

• Journal of Drive and Control
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• v.16 no.2
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• pp.15-21
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• 2019

In this study, the maximum system efficiency of the electro-hydrostatic actuators was experimentally investigated, where small size external gear pumps with volumetric displacement under 1.3 cc/rev were combined with a 400W servomotor as the prime mover. Since the efficiency data of the servomotor, gear pumps and hydraulic cylinder were not provided by the suppliers, experimental apparatuses for their efficiency measurement were extra built up. When a gear pump with a volumetric displacement of 1.27cc/rev was used on an electro-hydrostatic actuator system, the maximum system efficiency was not higher than 70%. This was because the most effective operation ranges of the motor and pump did not coincide each other. In order to match their operation ranges as one of the most crucial design factors, a speed reduction mechanism can be used, such as a timing belt. It was shown in the study that the maximum system efficiency could be increased from 70% to 76% in that way.

• Journal of the Korean Institute of Gas
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• v.26 no.2
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• pp.9-13
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• 2022

Electric wheelchairs, the output from the motor is mainly applied to a speed reducer using a power transmission device such as a belt or a chain. However, although a speed reducer using a belt or chain is a simple device, it occupies a lot of space and has a space limitation, so it is not suitable for an electric wheelchair driving part. However, since the speed reducer of the planetary gear type is decelerated on the same axis, the volume can be reduced, so the space constraint is less than that of the belt or chain type reducer. Therefore, in this study, a driving part that can obtain great propulsion with a speed reducer using a planetary gear type was developed through a study on the driving part of a wheelchair that can be switched between manual and electric. Accordingly, the tooth shape of the planetary gear applied to the reducer was designed using the Kisssoft program. In addition, the drive part was designed to be applicable to the existing wheelchair wheels, and the mechanism was optimized for the manual/electric switching principle and operation principle of the drive part. Based on the research contents, the final design and manufacture of the wheelchair reducer drive unit in the form of a planetary gear having one sun gear, two planetary gears and one ring gear was carried out.