• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.528-528
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• 2012

Recently, atmospheric pressure plasmas attract lots of interests for the useful applications such as surface modification and bio-medical treatment. In this study, a particle-in-cell Monte Carlo collision (PIC-MCC) simulation was adopted to investigate the discharge characteristics of a planar micro dielectric barrier discharge (DBD) with a driving frequency from 13.56 MHz to 162.72 MHz and with a gap distance of 80 micrometers. The variation of frequency, in the change in the electron energy probability function (EEPF). Through the relation between the ion trajectories and the frequency, results in the change of EEPFs is achievable with the turning point of frequency mode. Therefore, it is possible to categorize the efficient operation range of DBDs for its applications by controlling the interactions between plasmas and neutral gas for the generation of preferable radicals.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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• pp.864-865
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• 2006

Alumina microcomponents have distinguishing advantages over Si counterpart. However, the shrinkage of alumina, as high as 20%, makes it difficult to produce precision components meeting a high tolerance. A new fabrication process presented to greatly reduce the shrinkage by producing alumina microcomponents from ultrafine Al powder. The process consists of forming Al powder components through sintering and turning the Al powder component into alumina. In this way, the shrinkage occurring in sintering the Al powder component will be compensated by the expansion appearing when the Al powder component turns into alumina. The process has proven successful.

• Asia Pacific Journal of Business Review
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• 제2권2호
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• pp.45-59
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• 2018

Globalization is swapping the every possible corner of the globe steadily yet gradually. Mammoth like companies are penetrating the threshold of potential nations as freelancers and exploiting every inch of feasibility to carry out commercial activities. Undoubtedly, the entire world is experiencing the glare of new horizon. Even laggards nations are also turning out to be a country of immense potential and dynamism. They too, have awakened miserably to comprehend their self worth and entity while bearing the torch of Globalization. The shed of globalization have not only sprinkled capitalistic or mercantilist but even countries like China - once a hardcore communist country is also not remaining untouched with it. Albeit, the Dragon responding affirmatively to the hot current of Globalization yet their way is un-orthodoxical, strange and inventive. This case study discussed on major areas where India, the largest democracy in the world and six largest economy in the world are facing steep competition from China.

• 한국기계가공학회지
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• 제9권5호
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• pp.1-6
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• 2010

The wavelet transform is a popular tool for studying intermittent and localized phenomena in signals. In this study the wavelet transform of cutting force signals was conducted for the detection of a tool failure in turning process. We used the Daubechies wavelet analyzing function to detect a sudden change in cutting signal level. A preliminary stepped workpiece which had intentionally a hard condition was cut by the inserted cermet tool and a tool dynamometer obtained cutting force signals. From the results of the wavelet transform, the obtained signals were divided into approximation terms and detailed terms. At tool failure, the approximation signals were suddenly increased and the detailed signals were extremely oscillated just before tool failure.

• 한국산학기술학회논문지
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• 제3권1호
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• pp.38-43
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• 2002

본 논문은 자동으로 책장을 넘길 수 있는 장치에 대한 시스템 설계 및 제품개발에 관해 다룬다. 악보 또는 책을 손상시키지 않고 책장을 한 장씩 넘기기 위해 흡임모터를 이용했으며, 책장을 넘길 때 책을 고정, 흡입 그리고 책장을 넘기는 일련의 동작을 마이크로프로세서에 의해 다수의 모터를 이용하여 구현하였다. 기존 제품은 사전에 한정된 낱장들을 다수개의 넘김바에 끼워야 하는 반면 본 장치는 사전 작업이 필요 없이 자동으로 낱장들을 넘긴다. 제작된 결과물을 이용하여 실증실험을 통해 본 장치의 효용성을 입증하고자 한다.

• Current Optics and Photonics
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• 제3권3호
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• pp.227-235
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• 2019

With slimmer, lighter and all-reflective imaging systems in high demand for consumer and military applications, coaxially folded optical image systems are widely considered because they can extend focal length and reduce track length. Most of these systems consist of multiple surfaces, and these surfaces are machined on one element or grouping processing on two elements. In this paper, we report and first experimentally demonstrate an all-aluminum all-reflective optical system which consists of two optical elements, with two high order aspherical surfaces in each element. The coaxially folded system is designed with Seidel aberration theory and advanced optimization with Zemax. The system is made of all-aluminum material processing by single point diamond turning (SPDT). On this basis, we completed the system integration and performed an imaging experiment. The final system has the advantages of short track length and long focal length and broad application prospects in the micro-unmanned aerial vehicle field.

• 한국콘텐츠학회논문지
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• 제13권9호
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• pp.400-409
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• 2013

본 연구에서는 한국 운전자의 특성을 고려한 회전교차로 진입 임계간격을 조사하여 이를 기반으로 다양한 교통조건 및 다지 회전교차로에 대하여 그 효과를 분석하였다. 회전교차로의 임계간격은 4지, 5지, 6지, 그리고 7지에 대하여 현장조사를 수행하였으며, Raff의 추정기법을 이용하여 임계간격을 도출하였다. 도출된 임계간격은 모의실험을 위한 정산 및 통계적 검증과정을 거쳤으며, 이를 기반으로 다양한 조건에서 회전교차로 운영분석을 수행하였다. 그 결과 운영 교통량 및 회전비율 등에 따른 다지 회전교차로의 설계요소인 내접원 직경을 서비스수준별로 제시하였다. 이는 향후 회전교차로 설계지침에 반영할 수 있을 것으로 사료된다.

• 한국정밀공학회지
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• 제29권8호
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• pp.813-817
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• 2012

Laser assisted machining (LAM) is machining method that performs a machining for workpieces using laser beam preheating. LAM is in the early stage of its applications and has only been used in limited fields including turning, planning and micro end-milling throughout the world. LAM system should be able to move to the laser radiation direction and to rotate on a tool path for machining of complex shapes. A laser module with two-axis manipulator is designed in this study. It has been performed static structural analysis and shape modification of the manipulator. As the results of shape modification it has been obtained better results than the initial model. These results will be able to use in development of the two-axis manipulator.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.922-925
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• 2002

Klystron which is micro wave amplifier tube are mainly used in fields of science such as accelerator, nuclear fusion, broadcasting, communication fields, and defense industry fields, tract. The quality of Klystron anode and cavity are determined by form accuracy and roughness of the worked surface. Therefore anode and cavity are restricted the from accuracy strictly and the surface roughness be under Rmax 0.03S. As a work material of anode and cavity, the oxygen-free copper, that is used for optical pares of aerospace and laser mirror is selected. An outside diameter of material is $\Phi$100 mm and an inside diameter is $\Phi$30~33 mm. In this study, to find the optimum ultra precision cuffing condition of oxygen-free copper with diamond turning machine, the surface roughness is examined for various diamond toot nose radius, main spindle speed, fred rate and depth of cut. As a result of experiment, we could machined the anode and cavity with a surface roughness within Ra 3.2 nm, a form accuracy within 0.01 $\mu\textrm{m}$.

• 한국정밀공학회지
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• 제26권12호
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• pp.123-130
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• 2009

This study presents the application of a polymer behavior model that considers fluid mechanics and heat transfer effects in a deposition system. The analysis of the polymer fluid properties is very important in the fabrication of precise microstructures. This fluid behavior model involves the calculation of velocity distribution and mass flow rates that include the effect of heat loss in the needle. The effectiveness of the proposed method was demonstrated by comparing estimated mass fluid rates with experimental values. The mass fluid rates under various process conditions, such as pressure, temperature, and needle size, reflected the actual deposition state relatively well, and the assumption that molten polycaprolactone(PCL) is a non-Newtonian fluid was reasonable. The successful fabrication of three-dimensional microstructures demonstrated that the model is valid for predicting the polymer behavior characteristics in the microstructure fabrication process. The results of this study can be used to investigate the effect of various parameters on fabricated structures before turning to experimental approaches.