• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 춘계학술대회논문집
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• pp.169-172
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• 2004

This paper proposes a new MR(magneto-rheological) brake utilizing composite modes of MR fluid. Its basic structure and design scheme are almost the same with the conventional MR brake, but for slots in a rotating disk or shell. The slots enable the proposed MR brake to use a new mode, so-called, ‘direct cutting chain mode’as well as shear mode, which results in increasing the braking force(almost 150% compared to the case without slots). Some experimental results show that the proposed MR brake provide the sufficient braking force to be adopted for small portable force feedback devices.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.1858-1863
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• 2003

The properties of a machine tool greatly affect machining quality since a machine tool has large variance in its features. Machine tool makers want to find best machining condition with the one that they have built. Machine builders need to develop test specimen since it helps finding characteristics of machine tools when the machining properties of the specimen are analyzed. This paper develops test specimen to identify features of the main spindle, the feeding device, and the frame of a machine tool. The specimen is machined with a high speed machine and the features of the machine are analyzed with test items. They are surface roughness, overshoot in axial movement, errors in circular movement, feeding with small movement, and compensational error. This work can improve usability for a machine tool in machining practice.

• Tribology and Lubricants
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• 제11권5호
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• pp.66-70
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• 1995

In this investigation, a controlled-environment tribological test device has been used to study the friction coefficients of several grades of commercially-available coated and uncoated cemented carbide cutting tools in a dry air environment at different environmental chamber pressures. Tests were run in the block-on-ring configuration. The results suggest that the friction coefficient is sensitive to the level of air present, with a noticeable rise in friction coefficient with decreasing pressure or increasing vacuum level. The uncoated cemented carbide sufaces resulted in the highest friction values, whereas the coated grades yielded somewhat lower values even after the coating was removed. The results suggest the importance of friction control in the design of coatings for metal removal processes.

• 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.

• 드라이브 ㆍ 컨트롤
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• 제15권3호
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• pp.29-35
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• 2018

This paper presents the design of attachments for dual arms of disaster responding heavy machine. The heavy machine handles a variety of tasks such as cutting, shredding, picking and moving in unstructured environment. Despite the need for rapid response, the heavy machine has difficulty in repeatedly replacing the attachment depending on the task. Thus, we propose a method to solve this physical and functional contradiction relation by using TRIZ separation principles. Above all, the existing equipment and the required working scenarios were surveyed and summarized in order to separate the attachments functionally for right-handed, left-handed and two-handed operation. Then, we proposed the design directions and conceptual design as following: multi function type attachment A, for precise operation and various operations; grab type attachment B, for grasping irregular objects and auxiliary device for both arms to handle bulky objects.

• 조명전기설비학회논문지
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• 제27권5호
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• pp.81-88
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• 2013

A low voltage circuit breaker protects electrical equipments from over current and short faults of system by cutting the power supply. The breaker use a thermal magnetic type trip device from the past. In recent years, electronic type relays are applied due to useful functions and services. The purpose of this development is full digitalizing of relay functions of a low voltage breaker. It includes separation of current sensor from current transformer, digital signal processing, high speed relaying, and voltage measuring for power meter. The suggestions are tested and implemented by making prototype and testing its all relay functions.

• 한국기계가공학회지
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• 제11권6호
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• pp.9-15
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• 2012

Vibrational film has been more employed in ear-phones or small type of speakers along with a wide use of portable multi-media equipments such as MP3 and MP4. However, the current hand work production process of diaphragms is inefficient. In this study, a die-and-mold and a single production forming machine are developed, and they result in a multi-production forming machine. The multi-production forming machine consists primarily of a film feeding unit and an unwinding unit. A vacuum suction device provides the film feeding unit, while the unwinding unit is obtained using an appropriate damper. The advantage of the developed single production forming machine is shown according to a proper voice test.

• International Journal of Internet, Broadcasting and Communication
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• 제7권1호
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• pp.20-22
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• 2015

Recently, the study of smart phone user habits has become a highly focused topic due to the rapid growth of the smart phone market. Indeed, sequential pattern analysis methods were efficiently used for web-based user habit mining long time ago. However, by means of simulations, it has been observed that these methods might fail for smart phone-based user habit mining. In this paper, we propose a novel approach that leads to a considerably increased performance of the traditional sequential pattern analysis methods by reasonably cutting off each chronological sequence of user logs on a device into shorter ones, which represent the sequential user activities in various periods of a day.

• 한국정밀공학회지
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• 제24권6호
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• pp.51-57
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• 2007

Creep-feed grinding is an effective technology processes to increase the productivity and efficiency in form grinding. This method has, however, some problems which the progress of abrasive wear around the cutting edge is remarkable, grinding force become intense and burn marks on the ground surface occur frequently. In order to solve this problems, it is proposed in this study to dress the grinding wheel continuously during the grinding process. The purpose of this research is. therefore, that CNC creep-feed grinding machine which has a continuous dressing device developed and some grinding experiments for determination of dressing conditions carried out.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 제6회 학술대회 논문집 일렉트렛트 및 응용기술연구회
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• pp.47-51
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• 2004

The aspherical lens are used as objective lens of optical pickup. The sample product is made before manufacturing the injection mould of lens to examine the design factor. The optimum cutting conditions of the main spindle speed, the depth of cut, the feed rate are found when we cut PMMA and PC lens sample with ultra-precision SPDT. The demanded surface roughness 10 nm Ra, aspherical form error 0.5 ${\mu}m$ P-V for aspherical lens of optical data storage device are satisfied for PMMA, but not satisfied for PC.