• 전기의세계
• /
• v.31 no.1
• /
• pp.68-73
• /
• 1982

An accurate mathematical model of permanent magnet stepping motor is proposed. On the basis of this model, micro-stepping control is experimented. A comparison is made between the Data experimented by micro-stepping control and the data predicted by the proposed model and by Leenhouts' earlier model. The result shows that the proposed model is more accurate than the earlier model, and micro-stepping can be attained by dividing a given step electrically, without adding much complexity to the control circuit, or degrading the speed of stepping motors.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.26 no.3
• /
• pp.285-291
• /
• 2017

Micro-needles are used as transferring devices for sampling of tiny constitute substances from biological bodies. Typically, nickel is used as a coating to improve the rigidity of micro-needles. This study introduces the methodology to manufacture a WC needle with very high hardness and toughness. Micro-EDM technology was used to manufacture micro-needles with holes $130{\mu}m$ in diameter and $2300{\mu}m$ in length. A micro-needle was aligned to the micro-EDM electrode using a custom two degree-of-freedom alignment system. A three-step manufacturing technique was developed to drill a micro-hole using a WC electrode. In the first process, an electrode $105{\mu}m$ in diameter was used to make a hole. Electrodes of 90 and $105{\mu}m$ diameters were used in the second and third process, respectively. Consequently, a WC micro-needle with an inner hole of $135{\mu}m$ diameter, length of $2300{\mu}m$, and outer diameter of $300{\mu}m$ was developed.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.29 no.6
• /
• pp.294-297
• /
• 2019

New insights about macro-step formation has been investigated. The phenomena of surface instability caused by the interaction between step flow and fluid flow was describe in mechanical way. The rotation of the seed crystal in a clockwise direction was applied with a speed varied from 30 to 200 rpm during the TSSG process on the Si- and C-faces 4H-SiC. The macro-steps were formed along the two specific directions at different locations on the crystal for each, i.e., [10-10] or [01-10] directions or both. From the results, it is suggested that the macro-steps were generated from the micro-steps by interaction between step flow and fluid flow during the rotation of seed crystal. Furthermore, The fluid flow could be effective to control the micro- and/or macro-step behavior during solution growth.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2010.02a
• /
• pp.86-86
• /
• 2010

Micro- and nanoscale texturing and control of surface energy have been considered for superhydrophobicity on polymer and silicon. However these surfaces have been reported to be difficult to meet the robustness and transparency requirements for further applications, from self cleaning windows to biochip technology. Here we provided a novel method to fabricate a nearly superhydrophobic soda-lime glass using two-step method. The first step involved wet etching process to fabricate micro-sale patterns on soda-lime glass. The second step involved application of $SiO_x$-incorporated DLC to generate high intrinsic contact angle on the surface using chemical vapor deposition (CVD) process. To investigate the effect of surface roughness, we used both positive and negative micro-scale patterns on soda-limeglass, which is relatively hard for surface texturing in comparison to quartz or Pyrex glasses due to the presence of impurities, but cheaper. For all samples we tested the static wetting angle and transparency before and after 100 cycles of wear test using woolen steel. The surface morphology is observed using optical and scanning electron microscope (SEM). The results shows that negative patterns had a greater wear resistance while the hydrophobicity was best achieved using positive patterns having static contact angle up to 140 deg. with about 80% transparency. The overall experiment shows that positive patterns at etching time of 1 min shows the optimum transparency and hydrophobicity. The optimization of micro-scale pattern to achieve a robust, transparent, superhydrophobic soda-lime glass will be further investigated in the future works.

• Proceedings of the KIEE Conference
• /
• 2011.07a
• /
• pp.1318-1319
• /
• 2011

In this paper, we analyzed of growth and electrical characteristics of micro-cracks with thermal effect in PV module. The micro-cracks are increasing the breakage risk over the whole value chine from the wafer to the finished module, because the wafer or cell is exposed to mechanical stress. we experimentally analyze the direct impact of micro-cracks on the module power and the consequences after artificial aging. The first step, we made micro-cracks in PV module by mechanical load test according to IEC 61215. Next, PV modules applied the thermal cycling test, because microcracks accelerated aging by thermal cycling test. according to IEC61215. Before every test, we checked output and EL image of PV module.

• International Journal of Precision Engineering and Manufacturing
• /
• v.1 no.1
• /
• pp.152-159
• /
• 2000

In piercing operation for small hole in very thin plate, micro burrs are formed. The micro burr is very difficult to remove because the thin plate is to be deformed during deburring and deteriorate accuracy. As a first step to remove the micro burrs effectively, the burr must be measured accurately as much as possible. For most micro burrs are so small as less than 10$\mu\textrm{m}$, it is very difficult to measure. Several methods are reviewed to measure the micro burr formed in piercing operation from very thin plate with thickness less than 0.1mm. Also the effective deburring methods are reviewed. Barreling ultrasonic and chemical deburring methods are performed and the results are compared.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.14 no.12
• /
• pp.994-1000
• /
• 2001

In this paper, using micro-stereolithography technology, I fabricated a liquid analyzer to measure ion concentration of a solution. Micro-stereolithography is a technology to fabricate 3-dimensional structure by applying laser beam on liquid photo-polymer. This technology makes it possible to do preassemble fabrication without any extra assembling step after the process. So, the liquid analyzer could be fabricated at very low cost with very simple process by micro-stereolithography technology. The liquid analyzer consists of a chamber for containing the solution, a pump using piezoelectric effect of PZT disk, a static mixer and a sensor for measuring ion concentration using Pt electrodes.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.22 no.2
• /
• pp.123-127
• /
• 2009

In order to get more higher integration density of devices, it is getting to be used more and more micro via interconnection lines for interconnecting layers or devices. However, it is very important to enhance the electrical characteristic by reducing the electrical resistivity of micro via interconnection line because it affects the reliability of packaging. In this paper, Micro vias were patterned with a diameter from 10 to 100 um by increasing the step of 10 um and 100 um height and were fabricated by micromachining technology to investigate the electrical characteristic of micro via interconnection lines. These micro vias were filled with copper by electroplating process with appling pulse current mode. And the electrical characteristics of micro via interconnection lines were measured. The measured value of electrical resistivity shows with a range from 20 to $26\;m{\Omega}$. This value from micro via interconnection lines fabricated by pulse current mode electroplating process shows better result than the resistivity from than micro via interconnection lines fabricated by DC mode ($31\;m{\Omega}$).

• Proceedings of the KIPE Conference
• /
• 2006.06a
• /
• pp.311-315
• /
• 2006

This paper proposes 5 phase step motor drive system has high performance dynamics with micro step control has current controller. In this paper, analog current controller has been developed to minimize system size and cost. The validity of the proposed technique is verified through experimental results of position control robot.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.10 no.1
• /
• pp.78-85
• /
• 1986

This study has been made to investigate Behavior of the fatigue crack propagation for the purpose of taking into consideration the fatigue behavior Which initiate and propagate in tip of defect of the defected specimens, Which Contain the micro-hole or micro-slit. Especially, the specimens have been conducted with high-freguency heat treatment of 850.deg. C, 1050.deg. C to consider strength elevation of defected specimens. The results of this study are as follow; (1) The case of the same in the length of crack, the fatigue crack propagation rate of the micro-slit is always faster than that of micre-hole. But, the first step of the fatigue crack propagation it is not always so. (2) Fatigue crack propagation rate of specimens with micro-slit or micro-hole which have been treated with high-frequency heat treatment satisfy the following formula between the fatigue crack propagation rate and nominal stress; dl/dN .var..sigma.$^{m}$ *l$^{n}$ .