• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 Proceedings ICPE 98 1998 International Conference on Power Electronics
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• pp.366-373
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• 1998

In this paper, a new control strategy to reduce switching losses in three-phase voltage-source PWM converters is proposed according to Modified-Period-Average-Model (MPAN). The basic concept of this strategy is aimed at calculating the phase control voltages for controlling the source currents to be sinusoidal and in phase with the source voltages, and reducing the number of switching in each period. The phase control voltages of Period-Average-Model(PAM) is obtained according to analyzing the operation of PWM converter. In order to reduce the sensitivity to system parameters in PAM, MPAM is deduced. Then a square wave whose frequency is three times of utility frequency is added to the phase control voltages derived from MPAM. The control strategy reduces the switching losses since there exists about one-third blanking time for every phase in one period. The theoretical derivation and the control strategy are experimentally verified on a 2.5 kW three-phase voltage source converter.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2004년도 추계학술대회논문집
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• pp.19-22
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• 2004

Shearing including punching, blanking, trimming, slitting, etc is one of the most frequently used processes in sheet metal manufacturing. It has been widely using for manufacturing autobody, electronic components, aircraftbody, etc. In this paper, it has been researched by the experimental investigation to examine the influence of shearing processes parameters such as clearance, cutting angle, material properties, etc. From the results of experiment, it has shown that it gives the small variations at burr height below the proper clearance and it also presents that it is no affected the variations of cutting angle.

• 한국정밀공학회지
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• 제13권6호
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• pp.27-33
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• 1996

In this study, a CAD/CAM system for axisymmetric deep drawing processes has been developed. An approach to the system is based on the knowledge based system. Under the environment of CAD/CAM software of Personal Designer, the system has been written in UPL. The geometries of intermediate and final object in deep drawing process, including processes parameters are input for the CAD/CAM system. The input data can be obtained from the results of Pro_Deep. The parts drawing of die sets for each process is generated in tool design module of the CAD/CAM system. Also. the die assembly drawings can be obtained. NC commands for machining of the part can be generated in the developed CAD/CAM system.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1994년도 추계학술대회 논문집
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• pp.757-762
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• 1994

본 연구에서는 정밀진단가공을 위한 파인 블랭킹 기술 개발을 위한 파인 블랭킹용 전용 프레스를 사용 하지 않고 범용 유압 프레스에서 조보 유압 장치에 의해 압력을 조절해가면서 가공특성에 관한 실험적 연구와 이론 해석을 수행한다. 실험을 위해 파인 블랭킹 금형과 유압 장치를 설계 제작하고, 정밀진단 특성에 제일 큰 영향을 미치고 있는 V-돌기( Vee-ring)의 유무와 위치 그리고 스트리핑력 및 카운터 펀 칭력 변화에 따른 제품 정밀도를 조사해 가면서 최적의 정밀도 예측 수단으로 적절함을 확인할 수 있었으며, 실험결과는 작업 조건에 관계없이 모든 제품이 깨끗한 전단면을 나타내고 있으며, 일반적으로 스트리핑력이 감소할수록, 그리고 카운터 펀칭력이 증가할수록 캠버량이 감소하고 특히 카운터 펀칭력에 큰 영향을 받고 있음을 알 수 있었다. 이와같은 현상은 유한 요소해석에 의한 캠버량의 예측에섣고 정성적으로 잘 일치하고 있는 것으로 나타났다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 추계학술대회 논문집
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• pp.943-948
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• 1996

In this paper. we will discuss in making large size cylindrical shells with multithickness wall sections such as straight, stepped, tapered sides. These shells are constructed of type 6061 O temper aluminum starting with a blanking size of 877 mm plate. Its diameter to length ratio of 1 to 2.78 and a 36.7％ wall reduction is achieved by our continuous deep drawing process. This process required no in-process annealing. But after cold working, these shells is performed heat treatment to T6 condition. These shells are used for the making of seamless LPG pressure vessels after the spinning process. This process is composed of deep drawing, reverse redrawing, drawing-ironing and several ironing processes. In the verification of forming process design, we used DEFORM code.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 춘계학술대회 논문집
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• pp.204-208
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• 1995

Copper magnetron anode of a microwave-oven consists of an cylindrical outer-tube and various inner-vanes. The magnetron anode is produced by the complex process ; vane blanking, pipe cutting and sliver-alloy brazing of vanes. Recently, the backward extrusion process for forming vanes has been developed to avoid the complex procedures. The developed process is analyzed by using upper-bound elemental technique(UBET). In the UBET analysis, the upper-bound load, the configuration and the vane-height of final extruded product are determined by minimizing the total power consumption with respect to chosen parameters. To verify theoretical analysis, experiments have been carried out with pure plasticine billets at room temperature, using different web-thickness and number of vanes. The theoretical predictions both for forming load and vane-height are in reasonable agreement with the experimental results.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2005년도 추계학술대회 논문집
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• pp.448-452
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• 2005

Punching/blanking/shearing is among the oldest and most frequently used sheet metal forming process. We have developed the shear device for burrless cutting using the micro wire. Since the burr minimization and fine shear plane, this paper is a study on the effect of the shear angle and clearance of the cutter-cutter. And, we confirm the tendency of the shear plane. It is impossible to completely remove the burr in the shearing process. In order to minimize the burr size and fine shear plane, we have accomplished the various experiment conditions such as the shear angle and clearance. Despite the quality of shear plane is not good enough yet, it is possible to make the burr minimization and fine shear plane by the optimization of process parameters.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 춘계학술대회 논문요약집
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• pp.220-220
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• 2004

최근 들어 블리스터 포장방식은 제품을 뜯어보지 않고 제품을 확인할 수 있는 장점을 가지고 있어 여러 가지 상품포장에 이용되고 있다. 대부분의 건전지의 포장 역시 블리스터방식을 이용하여 포장을 하고 있다 그런데 카메라 및 각종 휴대용 전자장치에서 널리 사용되고 있는 리튬전지의 경우에서는 전지 자체가 가지고 있는 폭발위험성 때문에 블리스터 포장을 할 때 각별한 주의가 필요하다. 그러나 국내를 비롯한 국외에서도 일반 알카라인 전지 포장기계를 구조 변경하여 사용하고 있고 리튬전지 특성을 고려한 리튬전지 전용 블리스터 포장기는 개발되지 않고 있다.(중략)

• 한국통신학회:학술대회논문집
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• 한국통신학회 1984년도 춘계학술발표회논문집
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• pp.9-12
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• 1984

A digital TV CODEC has been implemented. This CODEC uses a pulse code modulation with a resolution of 9 bits per sample and generates digital ouput at the rate of 90.194Mb/s. In this system, we aadopted a horizontal blanking control scheme to meet the contraint of 90.194Mb/s transmission rete, conswequently ontaining data compression of 9.4%, our system's performances have been measured. Its SNR

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2001년도 춘계학술대회 논문집
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• pp.231-234
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• 2001

Shearing, including blanking, trimming, piercing, etc, is one of the most frequently used processes in sheet metal manufacturing. In this paper, an individual set of tooling with an in-die sensor was designed and precisely fabricated to carry out the experiment for the shearing process investigation. Through various experiments, it has been examined the influence of process parameters such as clearance, edge material properties and pad configuration. Since the tension between the part and the scrap increases when the clearance increases, the clearance should be selected properly in order to reduce the burr height. Also removal of the lower pad makes the sheared surface worse and the shearing system unstable. The shearing force increases when the clearance decreases and the friction of the tooling material decreases. Dynamic reaction force is also important to obtain the fine sheared surfaces.