• 한국기계가공학회지
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• 제20권4호
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• pp.87-93
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• 2021

The mold industry is competitive, and mold should be processed under optimal conditions for efficient processing. However, the cutting conditions of the ball-end mill, which are a major factor in mold processing, are mostly set empirically, and considerable research is required for increasing the tool life and processing accuracy. In this study, a tool dynamometer and an eddy current sensor were used along with NI-DAQ, a data acquisition device, to obtain characteristic values of the cutting force and tool deformation during the ball end-mill machining of inclined surfaces at a machining center. The cutting force and tool deformation were measured in an experiment. It was found that the tool received the greatest cutting force at the end of the machining process, and the deformation of the tool increased rapidly. Furthermore, the cutting force tended to increase with the angle and number of rotations. The deformation increased rapidly during the machining of a 45° inclined surface.

• 한국공작기계학회논문집
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• 제11권6호
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• pp.1-9
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• 2002

This study describes the geometric characteristics and the 5-axis machining method in order to make end mill cutter coming with insert tips. End mill geometry is consisted of flute part and insert tip part. Flute part modeled by using ruled surfaces with constant helix angle, and insert tip part modeled by rectangular planes containing tapped hole of specified direction in its center. In this study, the modeled insert tip part considered both of a radial rake angle and a axial rake angle, because they were important cutting conditions. In order to machining the virtual end mill defined from geometric characteristics, we programmed a special software to machining the end mill considered in this study. This software can generate NC-codes about following processes, end milling or ball end milling of flute part end milling of rectangular plane, centering of hole, drilling of hole, and tapping of hole. Ant sampled end mills were modeled and machined on 5-axis CNC machining center with two index tables. Since machined end mills were very agreeable to designed end mills, we saw that the method proposed in this study can be very useful for manufacturing of end mill body with insert tip.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.624-627
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• 2002

A study on machining electrode for LEO(Light Emitted Diode) mold with shaped end-mill is presented. The electrode machining by shaped end-mill has been used for maximizing the productivity in manufacture of semiconductor mold. However, it has not been researched systematically for many difficulties such as the making of shaped end-mill, generation of tool path due to distinctive tool geometry, and so on. Tool path is generated on the shaped end-mill geometry and cutting force to provide accurate and efficient machining of electrode. The verification program can drive enhancement of productivity, selecting cutting conditions from experiment function of cutting force. Also, compensation of tooting and machina error can make the electrode accurate by modifying tool path. Therefore, the research on machining with shaped end-mill can contribute to enhancement of accuracy and productivity in building semiconductor mold.

• 한국해양공학회지
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• 제19권6호통권67호
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• pp.1-7
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• 2005

This paper deals with the design and aerodynamic analysis of a special-type impulse turbine, with an end plate for wave energy conversion. Numerical analysis was performed using a CFD code, FLUENT. The main idea of the proposed end plate was to minimize the adverse effect of tip clearance of turbine blade, and was borrowed from ducted propeller, with so-called penetrating end plate for special purpose marine vehicles. Results show that efficiency increases up to $5\%$, depending on the flow coefficient; a higher flow coefficient yields increased efficiency. Decrease of input coefficient CAwith an end plate is the main reason for higher efficiency. Performance of end plate at various design parameters, as well as flow conditions, was investigated; the advantages and disadvantages of the presentimpulse turbine were also discussed.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1994년도 추계학술대회 논문집
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• pp.176-181
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• 1994

As tools for machining precesion componants, end mills and ball end mill are widely used. For the end mill have longer cylindrical shape comparing diameter, they are liable to deflect when machining and induce geometrical error and deterioration of surface roughness. To improve the stiffness and the sharpness of the cutting edge of end mill, a software for manufaturing end mills are developed. The progeam predicts the result of helical flute grinding and the configuration of cutting edge which is located in cylindrical surface. Furthermore to facilitate the manufacturing end mill using CNC grinding machine, the setting conditions which satisfy the geometrical requirments like tool rake angle and stiffness are obtained.

• 반도체디스플레이기술학회지
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• 제16권2호
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• pp.79-84
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• 2017

This paper outlines the Taguchi optimization methodology, which is applied to optimize cutting parameters in end milling when machining STS304 with TiAlN coated SKH59 tool under up and down end milling conditions. The end milling parameters evaluated are depth of cut, spindle speed and feed rate. An orthogonal array, signal-to-noise (S/N) ratio and analysis of variance (ANOVA) are employed to analyze the effect of these end milling parameters. The Taguchi design is an efficient and effective experimental method in which a response variable can be optimized, given various control and noise factors, using fewer resources than a factorial design. An orthogonal array of $L_9(33)$ was used. The most important input parameter for cutting force, however, is the feed rate, and depending on the cutter rotation direction. Finally, confirmation tests verified that the Taguchi design was successful in optimizing end milling parameters for cutting force.

• Geomechanics and Engineering
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• 제23권6호
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• pp.523-533
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• 2020

The current study focuses on the effect of the end shape of steel pipe piles on installation effort and bearing resistance using the pressing method of installation under dense ground conditions. The effect of pile rotation on the installation effort and bearing resistance is also investigated. The model steel piles with a flat end, cone end and cutting-edge end were used in this study. The test results indicated that cone end pile with the pressing method of installation required the least installation effort (load) and showed higher ultimate resistance than flat and cutting-edge end piles. However, pressing and rotation during cutting-edge end pile installation considerably reduces the installation effort (load and torque) if pile penetration in one rotation equal to the cutting-edge depth. Inclusion of rotation during pile installation reduces the ultimate bearing resistance. However, if penetration of the cutting-edge end pile equal to the cutting-edge depth in one rotation, the reduction in ultimate resistance can be minimized. In comparing the cone and cutting-edge end piles installed with pressing and rotation, the least installation effort is observed in the cutting-edge end pile installed with penetration rate equal to the cutting-edge depth per rotation.

• Tribology and Lubricants
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• 제36권3호
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• pp.168-192
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• 2020

In recently designed diesel engines, the running conditions for piston-pin bearings have become severe because of the higher combustion pressure and increased temperature. Moreover, the metal removal from the bushing material has strongly reduced the ability of the antifriction material to accept asperity contacts. Therefore, it is necessary to find ways of reducing wear scar on the connecting-rod small-end bushing and piston-pin boss bearing related to the higher combustion pressure on the power cell of an engine. In this work, the position and level of material removal from the surfaces of the bushing and bearing under such severe operating conditions - for example, maximum power and torque conditions of a passenger car diesel engine - are estimated for several combinations of surface roughness. First, piston-pin rotating motion is investigated by calculating the friction coefficient at piston-pin bearings, the oil film thickness, and the frictional torques induced by hydrodynamic shear stress. Subsequently, the wear scarring on the surfaces of a connecting-rod small-end bushing and two piston-pin boss bearings related to piston-pin rotational motion is numerically calculated under the maximum power and torque operating conditions. This work is helpful to determine the reasonable surface roughness of the bushing and bearing for reducing wear volume occurring at the interface between a bearing and a shaft.

• 한국지반공학회논문집
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• 제18권4호
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• pp.21-32
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• 2002

말뚝 선단 조건에 따른 충격반향기법의 시간영역 신호를 실내 모형실험에 의하여 분석하였다. 선단조건으로는 자유단, 고정단, 암반 근입, 연약 선단부의 네 가지 조건을 고려하였으며, 이를 위하여 폴리우레탄 재질의 모형말뚝과 모노캐스트 재질의 모형암반을 제작하여 실험을 수행하였다. 실내실험 결과 각각의 경계조건에 대한 신호의 특성을 파악할 수 있었으며, 말뚝 선단 조건뿐만 아니라 말뚝과 주변 암반과의 부착상태도 추정할 수 있는 가능성을 확인하였다. 또한 실내 모형실험의 결과를 검증하기 위하여 현장실험을 수행하였으며, 암반 근입 말뚝에 대한 신호 분석 결과 충격반향기법에 의한 현장타설말뚝의 비파괴 건전도 평가는 적용성이 충분히 있는 것으로 파악되었다.

• 멤브레인
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• 제26권4호
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• pp.266-272
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• 2016

전량여과(dead-end filtration)를 사용하여 계란 난백용액으로부터 라이소자임 효소의 분리정제에 대한 연구를 수행하였다. 전량여과 시 사용된 한외여과 막의 분획분자량과 난백용액의 pH 변화에 따른 라이소자임의 난백에 존재하는 다른 종류의 단백질인 오발부민과 콘알부민에 대한 막을 통한 투과선택도(permselectivity)를 측정하여 투과선택도가 가장 큰 값을 나타내는 전량여과의 최적 운전조건을 결정하였다. 이 결과 난백용액으로 라이소자임을 효과적으로 투과 분리시키기 위한 최적 운전조건은 한외여과 막의 분획분자량 30 kDa, 난백용액의 pH 11이었다. 최적 운전조건에서 난백 내 총 단백질에 대한 라이소자임의 투과선택도가 약 83의 가장 큰 값을 나타내었다.