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레이저의 산란 패턴을 이용한 마이크로 로드의 변위 및 회전 측정
신현근(Hyun-Geun Shin),황선욱(Sun-Uk Hwang),김정대(Jun-Dae Kim),이용구(Yong-Gu Lee) (사)한국CDE학회 2011 한국 CAD/CAM 학회 학술발표회 논문집 Vol.2011 No.1
Optical trapping is very useful to assemble micro-parts. Assembly of micro-parts requires one to control their positions and postures precisely. For the precise control, information related to positions and postures should be obtained through accurate measurement. In this paper, the measurement experiments are conducted by means of QPD (Quadrant Photodiode) using laser scattering pattern that happens when laser hit the micro-rods. To obtain the reference data of the displacement and rotation of micro-rods, micro-rods are fabricated stuck on a substrate. The displacement reference is measured by moving laser along with micro-rods in length and thickness. The rotation reference is measured by locating laser at a fixed point of micro-rods that are fabricated with some angles.
신현근(Hyun-Geun Shin),박일석(Il Seouk Park) 대한기계학회 2013 大韓機械學會論文集B Vol.37 No.11
흡착식 제습기에 적용되는 제습 로터는 높은 제습 성능을 달성키 위해, 흡수율이 높은 재질로 구성된 수많은 미세 채널을 포함하고 있다. 본 연구에서는 습공기 흐름에 의해 나타나는 제습 로터 내부의 반복적인 흡착/탈착 과정에 대한 수치해석 결과를 소개한다. 수치해석의 정확도와 효율성을 고려하여 흡습층 내부에서는 표면 확산(surface diffusion)만을 고려하여 해석을 수행하였다. 해석결과는 이전의 연구와 비교하였고, 온도에 대한 비교 오차는 약 2%이하인 점을 감안하여 해석결과가 매우 잘 일치하는 것을 확인하였다. 단일 채널 내부에서 유동층 (flow layer)과 흡습층 (desiccant layer) 간 열/물질전달 연계 해석을 통하여 채널 내부의 수증기 분율, 흡수된 물 분율과 온도 등에 대한 시간 및 공간적 변화를 나타내었다. A hygroscopic rotor comprises many microchannels with high adsorption characteristics. In this study, the iterative adsorption/desorption processes that were affected by the humid air flow in a channel were numerically simulated. In consideration of the accuracy and computational costs, in the desiccant layer, only surface diffusion was considered in this simulation. The results were compared with the previous numerical results and found to show good agreement. By conjugating the heat and mass transfer between the desiccant and the flow layers, temporal and spatial changes in the vapor mass fraction, adsorbed liquid water mass fraction, and temperature in the channel were presented.
한국 이유자돈에서 검출된 돼지 유행성 설사 바이러스의 유전자 서열 분석
신현근 ( Hyun Geun Shin ),김영훈 ( Yeon Hun Kim ),서태원 ( Tae Won Seo ),한정희 ( Jeong Hee Han ) 한국가축위생학회 2009 韓國家畜衛生學會誌 Vol.32 No.1
Porcine epidemic diarrhea virus (PEDV), an enveloped single stranded RNA virus in the family Coronaviridae, causes acute viral enteric disease in piglets. Recently outbreaks of porcine epidemic diarrhea (PED) have been rare in Europe but frequent in Asia. In Korea, the increase of PED prevalence is showing specially in postweaning pigs. The purpose of this study was to investigatenucleotide sequence of nucleocapsid protein gene of PEDV field isolates from postweaning pigs in Korea and get more information about the viruses. A total of 15 postweaing pigs clinically suspected of PEDV infection by severe watery diarrhea and dehydration were used in this study. Viral RNA was extracted from small intestines and stools of the pigs. The N gene was amplified by nested RT-PCR, purificated, sequenced, analyzed and then compared with published sequences of other PEDV strains. Three PEDVs were isolated from the suspected postweaning pigs. The N gene of three PEDV field isolates consisted of 483 nucleotides. These PEDV field isolates showed nucleotide sequence homology range from 99.6% to 95% with Chinese strains, from 99.8% to 95.2% with Korean strains, from 97.3% to 95.7% with Japanese strains and from 96.5% to 95.7% with Belgium and British strains. The encoded pritein shared range from 98.8% to 95.6% with Chinese strains, from 99.4% to 95% with Korean strains, from 97.5% to 96.3% with Japanese strains, from 95.6% to 95% with Belgium and British strains. By phylogenetic tree analysis based on nucleotide sequence, three PEDV field isolates were clustered into two groups which were Chinese isolate groups and other Korean isolate groups. These results indicated that some of PEDV field isolates prevailing in Korean postweaning pigs may be associated with those of Chinese strains and other Korean strains.
신현근(Hyun-Geun Shin),이용구(Yong-Gu Lee) (사)한국CDE학회 2010 한국 CAD/CAM 학회 학술발표회 논문집 Vol.2010 No.1
The manufacture of micro-machines requires an assembly of various shapes of microparts. One of the promising fabrication techniques for such microparts is two-photon photopolymerization. Using this method, microparts are usually formed being tethered to the substrate, in order not to lose them during post-processing. Detethering of microparts from the substrate is done just prior to the assembly by applying a severing action by a micromanipulator. Micro-manipulator must be able to apply a force that exceeds the yield strength of the tethering material and it must be able to approach the tether in an appropriate angle. Such design considerations will be discussed in this study.
마이크로 부품의 성형 정밀도 향상을 위한 레이저 초점 경로 교정
신현근(Hyun-Geun Shin),황선욱(Sun-Uk Hwang),이용구(Yong-Gu Lee) (사)한국CDE학회 2011 한국 CAD/CAM 학회 학술발표회 논문집 Vol.2011 No.1
Two-photon photopolymerization is a technique that fabricates micro-parts through solidification of photosensitive resin at the focal spot of laser. It needs to control the laser spot in calculated path to fabricate the micro-parts of required shape. For controlling laser spot, galvanometric or tilt mirror is usually used. These devices have errors when controlling laser focal spot such as reflection surface being off-axis, optical rotational difference between two axes. In addition, the alignment of optical system can never be perfect. Such problems lead to the degradation of fabrication quality. In this paper, a correction algorithm for distorted laser spot is presented. The algorithm represents the relationship between distorted laser spot position and reference position. The more sections the whole area is subdivided into, the better the accuracy of laser spot path will be. The algorithm is tested with tilt mirror.
김정대(Jung-Dae Kim),황선욱(Sun-Uk Hwang),신현근(Hyun-Geun Shin),이용구(Yong-Gu Lee) (사)한국CDE학회 2011 한국 CAD/CAM 학회 학술발표회 논문집 Vol.2011 No.1
Two-photon photopolymerization has recently been used for the fabrication of micro parts for microassembly. In order to increase assembly success rate, fabrication errors need to be reduced at a certain tolerance level. However, such a research for fabrication accuracy of micro part in two-photon photopolymerization is very rare. Generally, there exist several causes: reflecting mirror rotated off-axis, position error of laser scanner induced by incorrect arrangement of optical setup, laser pointing instability, laser power irregularity and mechanical stage movement errors. This paper aims at reduction of both length and angle errors within respectively, 10 percents and 5 degrees. A 10 micro-meter rod and 10 micro-meters cross shape are used for the length and angle error.