• Journal of the Korean Society for Precision Engineering
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• v.31 no.5
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• pp.381-387
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• 2014

This paper introduces a system to machine micro-sized patterns effectively on surface based on micro-milling process using tools with simultaneous rotation and oscillation, oscillation micro milling. To review the effectiveness of proposed concept, we integrated a micro-spindle supported by active magnetic bearings with a precision 3-axis air bearing stage using double-wedge mechanism, and tested this oscillation milling. Two types of oscillation milling were tested, which are linear oscillation milling with a flat end mill and elliptical oscillation milling with a ball end mill with 0.3 mm of diameter. The spindle was rotating 110 krpm and workpiece was moving constant speed of 2~8 mm/sec during the oscillation milling. As the results, multiple oval shape dimples were generated in regular spacing, and the variation of elliptical motion made different shapes of patterns. The results showed that proposed oscillation milling can be successfully used for machining repeated micro-patterns.

• Korean Journal of Materials Research
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• v.11 no.9
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• pp.792-796
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• 2001

For electron beam lithography and SEM(scanning electron microscopy) applications, miniaturized electrostatic lenses called a microcolumn have been fabricated. In this paper, we report the fabrication technique for 20~30$\mu\textrm{m}$ apertures of electron lenses based on silicon and Mo membrane using an active Q-switched Nd:YAG laser. Experimental conditions of laser micromachining for silicon and Mo membrane are improved. The geometrical structures, such as the diameter and the preciseness of the micron-size aperture are dependent upon the total energy of the laser pulse train, laser pulse width, and the diameter of laser spot.

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.2230-2232
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• 2000

This paper reports an electrostatically driven and electromagnetically sensed planar vibratory gyroscope based on a surface-bulk combined micromachining. The fabricated structure has comb electrodes which are 400${\mu}m$ thick, 18${\mu}m$ wide, 600${\mu}m$ long and separated by 7${\mu}m$ so that the height-gap ratio is about 57. It also has electroplated gold springs which are 15${\mu}m$ wide, 14${\mu}m$ thick and 500${\mu}m$ long on both sides of the seismic mass. The open-loop characteristics of fabricated gyroscope at atmospheric pressure are measured on a rate table. The fabricated gyroscope has a sensitivity of 30mV/deg/sec, and a resolution of 0.1deg/sec at atmospheric pressure. It is expected that non linearity of full scale output is less than 0.8% with. the dynamic range of $\pm$500deg/sec.

• Korean Journal of Optics and Photonics
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• v.12 no.6
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• pp.463-467
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• 2001

In this study, we developed a FFPI (fiber optic Fabry-Perot interferometer) pressure sensor using the Si diaphragm which measures pressure in vivo. The diaphragm and its supporting structure were etched in KOH solution and were fabricated with micromachining technology. For the configuration of the sensor, the length of the cavity of the Fabry-Perot etalon is 15 mm and one end of the etalon was bonded to a Si diaphragm with 507m thickness. When the area of the Si diaphragm was 2$\times$2 mm2 (cavity length 15 mm), it turns out that the pressure sensitivity was about 1.5 degree/kPa. The pressure sensor developed in this study showed that the phase change was linearly proportional to the increasing pressure in the range of 80 kPa.

• 한국생물공학회:학술대회논문집
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• 2000.11a
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• pp.115-118
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• 2000

A microfabricated cell chip was developed to evaluate drug effect on mouse B16-F1 melanoma cell line. The cell chip system consists of 8-well culture cartridge incorporated with interdigitated array gold electrodes on each well, lock-in amplifier, 8-well cell scanner and computer as a system controller. Impedance of an electrode is increased according to adherent cell growth on the electrode surface. In order to verify investigated. The change of impedance was measured differentially between a control electrode containing only media and cell-cultured sample electrodes with time.

• Proceedings of the KIEE Conference
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• 2001.07d
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• pp.2274-2276
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• 2001

본 논문에서는 미세 구조물 가공 기술(MEMS)로 제작된 실리콘 자이로스코프를 위한 폐루프 제어기를 주파수 가중 $H_{\infty}$ 제어 기법과 주파수 가중 모델 축소 기법을 이용하여 설계하였다. 실리콘 자이로스코프는 수 kHz 대의 공진 특성을 이용하여 각속도를 측정하는 센서로서, 공진 주파수 영역의 특성이 매우 중요하므로 주파수 영역을 고려하고 공정 오차를 감안한 주파수 가중 $H_{\infty}$ 제어기가 필요하다. 본 논문에서는 고차 강인 제어기의 회로적 구현과 ASIC화가 가능하도록 하기 위해, 주파수 가중 모델 축소 기법을 이용하여 공진 주파수 영역에서 성능을 유지하는 저차 제어기를 설계하였으며, 시뮬레이션을 통해 기존의 제어기 및 고차 제어기와 성능을 비교하였다.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.477-482
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• 2006

In this study, a micro vapor compressor has been designed, fabricated and tested. The micro vapor compressor was made of silicon substrates and fabricated by micromachining process. The compressor is driven by a piezoelectric actuator which is widely used in microfluidic systems because of its strong force and rapid response. The actuator is a bimorph structure which consists of a silicon membrane and a piezoelectric ceramic film. A simulation work was conducted on the performance characteristics of the compressor. The simulation investigated the flow rate variation under various back pressure conditions. Experimental works were carried out on the operation of a compressor and the test results were compared with the simulation results.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2019.10a
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• pp.7-7
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• 2019

우리나라에서의 대마는 마약류로 분류되어 기호용과 의료용 모두 법적인 제재를 받아왔으나 최근에 의료용 대마가 법적으로 허용이 되어 환자들에게 처방 받을 수 있게 되었다. 하지만 우리나라 사람들에게 대마는 환각성분을 가진 마약류로 깊이 인식되어 왔으며 의료용 대마에 대한 연구는 거의 전무한 실정이다. 노지재배에서 발생할 수 있는 범죄의 위험성, 자연교배에 의한 품질저하를 피할 수 있으며 재배조건(양액, 광조건, 광주기, 대기환경조성) 등을 제어할 수 있는 밀폐형 LED 식물공장은 의료용 대마 생산에 제일 적합한 모델이 될 수 있다. 식물체의 광합성은 가시광선 중 특정 파장 450nm 청색광과 660nm 적생광을 주로 이용하며 'LED (Light Emitting Diode) 발광다이오드'는 식물체의 광합성에 적합한 파장으로 광원을 조사할 수 있는 장점이 있다. 이러한 LED를 이용한 광합성은 식물체의 2차 대사물질 Anthocyanins, phenolic compounds 등의 향상과 생육에도 긍정적인 영향을 미치며 식물 뿐만 아니라 광합성을 하는 미세조류(micro algae)에서도 이용이 가능하며 해마토 코쿠스(Hematococcus)의 세포증식과 항산화물질 아스타잔틴(astaxathin)생산에 유용하게 쓰이고 있다. 최근 미국과 다른 나라에서도 기호용, 의료용 대마사업에 대한 관심이 높아지고 있으며 캐나다와 미국에서는 밀폐형 유리온실과 식물공장을 이용한 의료용 대마를 생산, 추출, 가공까지 하여 산업적인 영역을 넓히고 있는 실정이다. 특히, 실내재배에서는 광원이 필수적인 요소이며 식물생육에 선택적인 파장을 조사할 수 있는 LED와 재배조건을 정밀하게 제어할 수 있는 밀폐형 식물공장을 이용한 의료용 대마 생산에 대한 연구가 절실히 필요한 시점이다.

• Membrane Journal
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• v.32 no.4
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• pp.227-234
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• 2022

Wastewater is released from leather, textile, paint, wood, or dye processing industries as well as petroleum refining industries. Wastewater from these industries contains water pollutant such as heavy metals and nitrogen compounds and has high chemical oxygen demand (COD). While there various filtering pollutants from wastewater for safe disposal, membrane-based technology is one of the most efficient methods for its high efficiency and low cost. Among various membranes, zeolite membranes gain spotlight for its cost-effectiveness and have undergone a lot of research. This review is focused on recent progress in zeolite membrane for wastewater treatment in following order: i) wastewater treatment, ii) microfiltration membrane, iii) hollow fiber membrane, and iv) ultrafiltration membrane.

• Korean Chemical Engineering Research
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• v.47 no.5
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• pp.538-545
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• 2009

The principle and application of a scanning probe microscopy(SPM) are reviewed briefly, and a low-invasive single cell manipulation and a gene delivery technique using an etched atomic force microscopy(AFM) probe tip, which we call a nanoneedle, are explained in detail. The nanoneedle insertion into a cell can be judged by a sudden drop of force in a force-distance curve. The probabilities of nanoneedle insertion into cells were 80~90%, which were higher than those of typical microinjection capillaries. When the diameter of the nanoneedle was smaller than 400 nm, the nanoneedle insertion into a cell over 1 hour had almost no influence on the cell viability. A highly efficient gene delivery and a high ratio of expressed gene per delivered DNA compared the conventional major nonviral gene delivery methods could be achieved using the gene modified nanoneedle.