• Proceedings of the Korean Vacuum Society Conference
• /
• 2012.02a
• /
• pp.528-528
• /
• 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.

• Proceedings of the Korean Powder Metallurgy Institute Conference
• /
• 2006.09b
• /
• pp.864-865
• /
• 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
• /
• v.2 no.2
• /
• pp.45-59
• /
• 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.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.9 no.5
• /
• pp.1-6
• /
• 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.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.3 no.1
• /
• pp.38-43
• /
• 2002

In this study, we deal with the system design and development of the automatic page passing machine. In order to turn pages without injury of a book or a musical note, we used an inhalation motor. Also, when we turn over pages. the successive actions of fixation and inhalation are embodied by motors which are operated by a microprocessor. In traditional products. some limited pages must be fixed into the Turning Bar in advance. On the contrary, proposed equipment is able to turn over the pages of a book without laying the groundwork. Experimental results using produced facilities are presented to demonstrate the efficacy of the proposed equipment.

• Current Optics and Photonics
• /
• v.3 no.3
• /
• pp.227-235
• /
• 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.

• The Journal of the Korea Contents Association
• /
• v.13 no.9
• /
• pp.400-409
• /
• 2013

In this paper, considering the characteristics of the driver at roundabouts by investigating the critical gap acceptance on various traffic conditions, multi-legged roundabouts were evaluated. The gap acceptance and rejection of 4-legged, 5-legged, 6-legged, and 7-legged roundabout were surveyed on real fields, and the critical gap acceptance was estimated using Raff's methods. Derived the critical gap acceptance was processed calibration and validation for micro-simulation, and then multi-legged roundabouts under variable conditions such as variations of traffic volume, turning ratio, and size of inscribed circle diameter were evaluated to verify operating conditions of roundabouts. As the results, according to the operating traffic volume and turning ratio, the inscribed circle diameters were proposed at each level of service. These inscribed circle diameters were able to reflect the guideline of geometric design for multi-legged roundabouts.

• Journal of the Korean Society for Precision Engineering
• /
• v.29 no.8
• /
• pp.813-817
• /
• 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.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2002.05a
• /
• pp.922-925
• /
• 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 $\mu\textrm{m}$.

• Journal of the Korean Society for Precision Engineering
• /
• v.26 no.12
• /
• pp.123-130
• /
• 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.