• Transactions of the Korean Society of Machine Tool Engineers
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• v.12 no.3
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• pp.82-88
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• 2003

SGA(Single Genetic Algorithm) is a heuristic global optimization method based on the natural characteristics and uses many populations and stochastic rules. Therefore SGA needs many function evaluations and takes much time for convergence. In order to solve the demerits of SGA, ${\mu}GA$(Micro-Genetic Algorithm) has recently been developed. In this study, ${\mu}GA$ which have small populations and fast convergence rate, was applied to structural optimization with discrete or integer variables such as 3, 10 and 25 bar trusses. The optimized results of ${\mu}GA$ were compared with those of SGA. Solutions of ${\mu}GA$ for structural optimization were very similar or superior to those of SGA, and faster convergence rate was obtained. From the results of examples, it is found that ${\mu}GA$ is a suitable and very efficient optimization algorithm for structural design.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.13 no.3
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• pp.61-67
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• 2004

In micro hole punching process the burr occurs inevitably, but the burr must be minimized in order to improve the quality and accuracy of the product. In this study, magnetic field-assisted polishing technique is applied to remove the burr which exists in nozzles for ink-jet printer head and proved to be a feasible for deburring by experiment. The deburring characteristics of sheet metals was investigated changing with polishing time and magnetic abrasive size. After the deburring, the burr size has remarkably reduced and roundness of the hole also has improved.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.04a
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• pp.429-434
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• 2002

In order to improve the accuracy in the field of simiconductor and LCD research equipment, the demand of XYZ stage which is possible to control X axis, Y axis and Z axis has been increased steadly in place of the existing XY stage which is only practicable to X & Y axis positioning control. This paper presents a new pneumatic actuator for Micro-positioning control in the XYZ stage. Air pressure in a pneumatic actuator is controlled by the E/P Regulator. The control range of pneumatic actuator is about 100 micro-meters and it's construction concept is easy to apply a practical state

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1997.10a
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• pp.37-42
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• 1997

This paper describes result of experiment of parameters affecting the micro hole drilling time, kind of assisting gas and it's pressure. The result reveals that parameter value of 0.08J, 20Hz, dwell time of 300 microseconds can be a good machining condition to make micro hole diameter range of 50-70${\mu}{\textrm}{m}$, Assistant gas such air, O2, Ar, N2 was adapted. Assistant gas of air makes heat affected zone enlarge due to burning of material, also it makes hole irregular and damage because of refusion stick to caused by chemical reaction with Al2O3 ceramic material. O2(99.9%) has good characteristic to get good drilling and smooth surface on pressure of 0.2kgf/$\textrm{cm}^2$, but it is expensive. Ar, N2 makes material burn and crack severely and proved to be an appropriate but, Ar was better than N2.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.516-519
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• 2002

In this paper, a new type of inchworm motion actuator is introduced. This is consisted of two piezoelectric ceramics; one is for moving the slider, and the other is for clamping the slider in the guide way of the body. The linearity and positional accuracy of the system is good enough for the high precision motion. Since the system is more compact than the conventional system using three piezoelectric ceramics, it is applicable fur the micro-machine or MEMS. However, the effort for reducing the vibration, velocity discrepancy in the motion direction, and compensating the hysteresis behavior is additionally needed.

• Journal of Mechanical Science and Technology
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• v.14 no.11
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• pp.1244-1249
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• 2000

Burr and shape distortion are two main problems in micro-grooving. In this study, a simplified model is proposed based on large thrust force due to the tool edge radius. Experiments are conducted with a single crystal diamond tool on a 3-axis snaper-like machine varying the depth of cuts, and groove angles on brass, aluminum and OFHC. Experiments have shown that the thrust force becomes a dominant variable in burr generation compared to the principal force when the depth of cut is less than 2${\mu}m$. And fewer burrs develop on more brittle materials. Shape distortion is significant only when the groove angle is small and the depth of cut is larger than 30 ${\mu}m$.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2001.05a
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• pp.221-224
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• 2001

The dynamic characteristics of a hydraulic press for micro-stamping are investigated by Finite Element Analysis. This machine requires high precision in producing milli-structure of electric products such as TFT-LCD back-up light reflector. First, the modal analysis of the parts and the assembly of the hydraulic press is performed. Then, the sensitivity analysis is carried out. The results show that the bearing stiffness and the base mounting stiffness affect the specific mode shapes.

• Proceedings of the Korean Information Science Society Conference
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• 2005.07b
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• pp.286-288
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• 2005

MicroRNA (miRNA)는 작은 크기의 RNA분자로서 동식물의 유전자 발현 과점을 직접적으로 조절하는 인자로 알려져 있다. MiRNA는 보통 목표 유전자의 3'-UTR 영역에 상보성을 갖고 결합함으로써 작용하며 특히 miRNA의 5'부분의 8 nt 정도가 seed로서 중요하다고 알려져 있다. 반면 최근의 연구에 따르면 seed 부분의 서열의 조성 및 양상이 변화함에 따라 특이도가 결정됨을 알 수 있지만 기존의 컴퓨터를 이용한 miRNA 목표 유전자 예측 방법들은 이러한 정보를 활용하지 못한다. 본 논문에서는 열역학적인 수치와 서열의 조성뿐 아니라 miRNA:mRNA pair의 위치에 기반한 정보들을 학습에 자질로서 포함하여 목표 유전자를 예측한다. 그 결과는 위치 기반 자질이 학습 성능 향상에 중요하게 기여함을 보여준다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.105-109
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• 2001

The micro optical parts such as ferrules are required to be manufactured within very small tolerances, as the slight deviation of the tolerance would give very large amount of loss in communication efficiency. For efficient optical communication, outer diameter, fiber diameter, fiber separation and eccentricity are significant parameters to be inspected., Thus we developed an automatic inspection system to evaluate shape parameters of the optical fiber connectors(ferrule) upto submicron accuracy using machine vision. new optical probe of multi fields of views has been developed and the image processing and data analysis algorithms have been complemented in real time basis. The developed system is successfully used in the practical ferrule manufacturing industry, and about 0.1$\mu\textrm{m}$ accuracy can be obtained with very fast inspection time.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.5
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• pp.76-81
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• 2012

The continuing demand for increasingly slimmer and brighter liquid crystal display(LCD) panels has led to an increased focus on the role of the light guide panels(LGPs) or optical films that are used to obtain diffuse, uniform light from the backlight unit(BLU). And the most basic process in the production of such BLU components is the micromachining. LCD BLUs comprise various optical elements such as a LGP, diffuser sheet, prism sheet, and protector sheet with micro patterns. High aspect ratio patterns are required to reduce the number of sheets and enhance light efficiency, but there is a limit to the aspect ratio achievable for a given material and cutting tool. Therefore, this study comprised a series of experimental evaluations conducted to determine the machining feasibility in microcutting various aspect ratio patterns on electroless nickel plated die materials when using single-crystal diamond tools. Cutting performance was evaluated at various cutting speeds and depths of cut using different machining methods and machine tools.