• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 추계학술대회 논문집
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• pp.371-374
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• 1997

This study presents a new type of real-t~me CNC interpolator that is capable of generating cutter paths for ball-end milling of NURBS surfaces. The proposed surface interpolator comprises real-time algorithms for cutter-contact (CC) path scheduling and CC path interpolation. Especially, in this study, a new interpolator module to regulate cutting forces is developed. This proposed algorithm utilizes variable-feedrate commands according to the curvature of machined surfaces. The proposed interpolator is evaluated and compared with the conventional method based on constant feedrates through computer simulation.

• 대한기계학회논문집
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• 제12권4호
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• pp.652-661
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• 1988

본 연구에서는 이질, 이방성 적층 복합보(beam)의 이론적 충격 응답을 해석하 기 위하여 Sun의 고차 보 유한 요소 이론을 복합 재료 이론과 식(1)~식(3)의 접촉 법 칙을 고려하여 수정하였고, 이 중 충격 접촉력에 관하여는 각각 [90˚/45˚/90˚/-45˚ /90˚]$_{2S}$와[0˚/45˚/0˚/-45˚/0˚]$_{2S}$의 두 적층 형태를 가지는 흑연/에폭 시와 유리/에폭시 복합 재료에 대한 강구(steel ball)에 의한 충격해석을 하여, Yang 의 식에 의한 최대 접촉력과 비교 검토하였고, 다음 변형율 파형을 파동 전파(wave propagation)이론에 의해 비교 검토하므로써 이 수정된 이론의 타당성을 입증하였다.하였다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 춘계학술대회 논문집
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• pp.782-787
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• 1997

This paper proposes methods for pencil machining and uncut area machining. Based on Z-map represented by triangular facets, self-intersection-free offset surface is generated with K-offset method in case of ball mill and flat mill Pencil machining can elliminate overload area before main machining rough, semi-finish and finish cutting,preventing fluctuations of cutting forces in concave regions form causing bad machining condition. Low productivity is caused by uncut area which has excessive or irreguar finishing allowance. Uncut area machining has the finishing allowance keep uniformly on part surface. This paper deals with two types of uncaut area, machining detection of excessive area and user-defined area.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.162-167
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• 2003

Finish machining of a curved surface is often carried out by an NC system with curve interpolation in the field. This NURBS interpolation adopts a feedrate optimizing strategy based on both the geometrical information and dynamic properties. In case of a finish cut using a ball-end mill. the curve interpolator needs to take the machining process into account for more improved surface, while reducing the polishing time. In this study, the effect of low machinability at the bottom of a tool on surface roughness is also considered. A particular curve interpolation algorithm is proposed for generating feedrate commands which are able to control the roughness of a curved surface. The simulation of the machined surface by the proposed algorithm was carried out, and experimental results are presented.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2003년도 춘계학술대회 논문집
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• pp.184-189
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• 2003

In metal cutting operation, it is very important that predict cutting force and work surface. Vibration is an unstable cutting phenomenon which is due to the interaction of the dynamics of the chip removal process and the structural dynamics of machine tool. when Vibration occurs, it reduces tool life, results in poor surface roughness and low productivity of the machining process. In this study, the experiments were conducted in machining center without cutting fluid to investigated phenomenon of the Vibration. In the experiments, accelerometers were set up at the tail stock and tool holder and the signals were picked up. In this paper, surface roughness profiles will be generated under the ideal condition and the occurrence of the vibration based on the surface shaping simulation model.

• 한국공작기계학회논문집
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• 제15권4호
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• pp.39-43
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• 2006

A computer-controlled micro tribotester has been developed to investigate the friction and wear characteristics of thin coatings, which can be applied to silicon-based materials. In the developed system, a step motor gives a reciprocating movement and an electromagnet applies a load between a ball and a plate specimen. Test results confirmed that the application of load in the range of $0.03{\sim}1.8N$ and with a sliding speed of $4.44{\sim}7.70mm/s$ was successfully accomplished. Advantages of the developed micro tribotester are: (1) realization of micro load and displacement applicable to micro electromechanical systems(MEMS) using DC motor and electromagnet (2) continuously variable load and reciprocating speed; and (3) high reliability, which allows for unattended use for long periods.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문초록집
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• pp.352.1-352
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• 2002

Auditory experiments based on subjective responses were undertaken for the heavy and light weight impact noises, rubber ball impact noise and real impact noise. Relations between noise levels and subjective evaluations were also investigated. As a result, it was found that the subjective responses of all floor impact noise sources showed a similar trend except real impact noise. The noise class was rated with the range of sensible satisfaction by investigating the various social responses for the floor impact noise. (omitted)

• 한국CDE학회논문집
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• 제4권1호
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• pp.60-68
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• 1999

In reverse engineering (RE) sustems, the quality of the data aquisition process is crucial to the accuracy of the reverse engineered three dimensional computer-aided design (CAD) model. However, these tasks are predominantly done manually, and little work has been done to improve the efficiency of scanning by determining the minimum number of scans and the optimal scanning directions. In this paper, new scanning and registration methods using tooling balls are developed to assist in determining the optimal parameter for these processes. When the object to scanned has no concavity, attaching path of the object and its bounding rectangle are used for optimal scanning and registration. Then minimum number of tooling balls and their positions are calculated automatically. In the case of concave parts, the scanning plan should include a complete scan of the concave area. With the surface normal vector and the scanning direction, the minimum degree of rotating the part can be calculated. But the maximum rotation should be restricted in order to prevent occlusion of the part. Finally tow sample part ar scanned based on the proposed methods and the results are discussed.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 하계종합학술대회 논문집(2)
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• pp.369-372
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• 2001

This paper presents the design of high-speed virtual output queue(VOQ) management scheme for high performance cell/packet switch, which has a serial cross bar structure. The proposed VOQ management scheme has been designed for wire-speed routing with a pipelined buffer management. It provides the tolerance of requests and grants data transmission latency between the VOQ manager and central arbiter using a new request control method that is based on a high-speed shifter. The designed VOQ manager has been implemented in a field programmable gate array chip with a 77MHz operating frequency, a 900-pin fine ball grid array package, and 16$\times$16 switch size.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 춘계학술대회논문집
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• pp.1601-1608
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• 2000

This paper is concerned with the forced flexural vibration analysis of hard disk drive (HDD) spindle systems with multiple thin disks, supported by two ball bearings based on the finite element model. This is the extension of the previous work which analytically modeled every system component taking into account its structural flexibility and also the centrifugal stiffening effect especially for the disks. Among the end results, the forced time response is expectedly useful for the vibration control of the spindle itself or the position servo control of the magnetic head. On the other hand, the steady state responses such as the frequency response function and the unbalance response are useful for system identification. Futhermore, through a coordinate transformation the equations of motion is also derived with respect to the inertial frame for convenient analyses of certain classes.