• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.543-544
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• 2007

Micro-grid consists of micro-sources which adopt environmentally friendly and reliable power sources with independent real and reactive power control capability for providing premium power quality. This paper presents dynamic modeling and the stable operating range of the micro-grid system varying the parameters of the micro-sources. Case study results show the parameters affecting the stability of the micro-grid and the stable operating range of the micro-sources.

• 한국토양비료학회지
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• 제32권3호
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• pp.274-278
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• 1999

토성 조사 특히 토양 중의 점토 함량의 측정은 토양과 관련된 연구에서 흔히 이루어지는 분석이다. 본 연구에 관련된 연구에서 흔히 이루어지는 분석이다. 본 연구에서는 현재까지 점토 함량 측정에 널리 이용되고 있는 표준 hydrometer법이나 pipette법과 비교하여 보다 간편하고 신속한 분석법으로 제안되어 있는 micro-pipette법의 이용 가능성을 검토하였다. Micro-pipette법과 hydrometer법으로 측정된 점토 함량은 유의성이 높은 1:1의 상관관계를 가졌으며. micro-pipette법치 분석의 정밀도는 hydrometer법에 비교하여 크게 떨어지지 않는 것으로 나타났다. 또한 micro-pipette법은 짧은 침강 시간과 작은 침강 용기를 사용함으로써 작은 실험실 공간에서 많은 시료를 분석할 수 있었다.

• Imaging Science in Dentistry
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• 제37권1호
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• pp.27-33
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• 2007

Purpose : The research was done to investigate the effectiveness of 2D bony morphometry and microstructure of micro-computed tomography (micro-CT) on the osteoporotic bony change. We performed the bone morphometric analysis of proximal femur in ovariectomized rabbits with BMD and micro-CT examination. Materials and Methods : Twenty-one female (Newzealand, about 16 weeks old, 2.9-3.4kg) rabbits were used. Three rabbits were sacrificed on the day when experiment began (Baseline). The remaining 18 rabbits were divided into two groups. One group was ovariectomized bilaterally (OVX) and the other animals were subjected to sham operation (Sham). Bone specimens were obtained from the right and left femur of sacrificed rabbits. At intervals of 1, 2, 3, 5, 6 months respectively, BMD tests were performed on the proximal femur by using PIXlmus 2 (GE Lunar Co. USA), 2-dimensional bone morphometric analysis by custome computer program and 2D/3D bone structure analysis by micro-CT (Skyscan 1072, Antwerpen, Belgium). Statistical analysis was carried out for the correlation between bone morphometry, micro-CT and BMD Result : BV/TV, Tb.Th, Tb.N of micro-CT parameters showed higher values in sham group than OVX group. N.Nd/Ar.RI, N.NdNd, N.NdTm, N. TmTm, PmB/Ar.RI, 3-D BoxSlope of 2D morphometric parameters showed higher values in Sham group than OVX group. The micro-CT parameters of Tb.Sp, Tb.N were statistically significant correlated with BMD respectively. Several 2D morphometric parameters were statistically significant correlated with BMD respectively. Conclusion : Several parameters of 2D bony morphometry and micro-CT showed effective aspects on the osteoporotic bony change.

• 한국전자통신학회논문지
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• 제7권4호
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• pp.881-895
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• 2012

마이크로 로봇은 인간의 다양한 질병과 진단에 있어 유용한 도구로서 활용이 가능한데, 이러한 이유로 현재 세계의 많은 국가들은 마이크로 로봇의 제작과 개발에 관심을 기울이고 있다. 한국정부 역시 이러한 세계적 추세 속에서, 마이크로 로봇 개발에 대한 기술정책을 만들고 많은 노력을 하고 있다. 따라서 본고는 SWOT분석을 통해, 한국의 마이크로 로봇 기술동향과 개발현황을 분석하여 미래 한국의 마이크로 로봇에 대한 가장 합당한 발전방안을 모색한다. 연구결과, '박테리아 기반기술의 마이크로 로봇(C형-2)'과 '무배터리 자체추진기 자율이동 마이크로 로봇(C형-3)'과 같은, 한국에서 관련 최신 특허로 등록받은 마이크로 로봇에 대한 보다 집중적인 지원이 필요하며, 이 양 분야 모두 현재 세계적인 수준으로 성장하고 있으므로 지원 중인 마이크로 로봇 개발에 관한 예산을 더욱 늘리는 한편 보다 적극적으로 관련 기술개발을 추진해야 한다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 추계학술대회 논문집
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• pp.277-277
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• 2009

In this paper, PMPG (Piezoelectric Micro Power Generator) was investigated by ANSYS FEA (Finite Element Analysis) to decrease operating frequency and improve out power. The micro power generator was designed to convert ambient vibration energy to electrical power as a ZnO piezoelectric material. To find optimal model in low vibration ambient, the shape of power generator was changed with different membrane width, thickness, length, and proof mass size. Used the ANSYS modal analysis, bending mode and stress distribution of optimal model were analyzed. Also, the displacement with the frequency range was analyzed by harmonic analysis. From the simulation results, the resonance frequency of optimal model is about 373 Hz and confirmed the possibility of ZnO micro power generator for wireless sensor node applications.

• 센서학회지
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• 제18권5호
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• pp.372-376
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• 2009

This paper describes the characteristics of piezoelectric micro power generators by the ANSYS FEA(finite element analysis). The micro power generator was designed to convert ambient vibration energy to electrical power as a ZnO piezoelectric material. To find optimal model in low vibration ambient, the shape of power generator was changed with different membrane width, thickness, length, and proof mass size. Using the ANSYS modal analysis, bending mode and stress distribution of optimal model were analyzed. Moreover, the displacement with the frequency range was analyzed by harmonic analysis. From the simulation results, the resonance frequency of optimal model is about 373 Hz and investigate the possibility of ZnO micro power generator for ambient vibration applications.

• 한국생산제조학회지
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• 제21권1호
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• pp.26-32
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• 2012

In the present study, the stencil printing process using solder paste are numerically analyzed. The key design parameters in the stencil printing process are the printing conditions, stencil design, and solder paste properties. Among these parameters, the effects of printing conditions including the squeegee angle and squeegee pressure are investigated through finite element (FE) analysis. However, the FE analysis for the stencil printing process requires tremendous computational loads and time because this process carries micro-filling through thousands of micro-apertures in stencil. To overcome this difficulty in simulation, the present study proposes a two-step approach to sequentially perform the global domain analysis and the local domain analysis. That is, the pressure development under the squeegee are firstly calculated in the full analysis domain through the global analysis. The filling stage of the solder paste into a micro-aperture is then analyzed in the local analysis domain based on the results of the preceding global analysis.

• 전기학회논문지
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• 제56권5호
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• pp.841-847
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• 2007

This paper deals with the micro-grid consisting of micro-sources which adopt voltage sourced inverters with independent real and reactive power control capability for providing premium power quality. This paper presents dynamic modeling and the stable operating range of the micro-grid system varying the parameters of the micro-sources. The fundamental frequency model of the micro-source inverters are considered to form a dynamic model of the micro-grid system. Stability analysis is performed based on the linearized dynamic model of the micro-grid system. Case study results show the parameters affecting the stability of the micro-grid and the stable operating range of the micro-sources.

• 한국전산유체공학회지
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• 제9권2호
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• pp.36-42
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• 2004

Low-speed gas flows in micro-channels are investigated using a kinetic theory analysis. The Boltzmann equation simplified by a collision model is solved by means of a finite difference approximation with the discrete ordinate method. Calculations are made for flows in simple micro-channels and a micro-fluidic system consisting of two micro-channels in series. The results are compared well with those from the DSMC method and an analytical solutions to the Wavier-Stokes equations. It is shown that the present method is a useful tool for the modeling of low-speed flows in micro-channels.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 춘계학술대회논문집
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• pp.755-761
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• 2003

Recently, the development of mobile devices demands information storage systems to use micro drive devices and cheap media. These should have several characteristics, for example, the subminiature of size, the robustness of shock, the minimum of cost and power consumption, and the removability of multiple applications. A conventional optical disk drive is more suitable for these specifications than the others. The optical storage system of the new generation to use a blue laser and a high numerical aperture (NA) is the perfect candidate for micro optical disk drives. In this paper, the micro actuator that can be applied to a micro optical disk drive is designed by response surface methodology to use a structural analysis and an electro-magnetic analysis. Based on above results, the coarse actuator and fine actuator are designed and improved from the point of view of the size and the power. Consequently, the designs of a micro actuator are proposed through these courses.