• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.32 no.5
• /
• pp.396-401
• /
• 2008

Minimization of processing time in two-photon stereolithography (TPS) has been one of important issues. Generally, a voxel scanning method (VSM) has been used in TPS because the method is very profitable for the stable fabrication irrespective of jittering and response time of scanning equipments such as a stage and a galvano-scanner. However, supplementary processing time due to the on/off control of a shutter for the generation of each voxel is required inevitably in VSM; by this reason, much processing time takes to fabricate largescale micropatterns and three-dimensional patterns. In this work, a continuous scanning method (CSM), generating patterns by movement of beam focus with a constant speed, is proposed for the improvements of scanning speed and precision in TPS. Some line patterns are fabricated by each scanning method to demonstrate the usefulness of CSM with viewpoints of scanning speed and precision.

• Proceedings of the KSRS Conference
• /
• 2003.11a
• /
• pp.241-243
• /
• 2003

This paper presents an algorithm that automatically extracts buildings among many different features on the earth surface by fusing LIDAR data with panchromatic aerial images. The proposed algorithm consists of three stages such as point level process, polygon level process, parameter space level process. At the first stage, we eliminate gross errors and apply a local maxima filter to detect building candidate points from the raw laser scanning data. After then, a grouping procedure is performed for segmenting raw LIDAR data and the segmented LIDAR data is polygonized by the encasing polygon algorithm developed in the research. At the second stage, we eliminate non-building polygons using several constraints such as area and circularity. At the last stage, all the polygons generated at the second stage are projected onto the aerial stereo images through collinearity condition equations. Finally, we fuse the projected encasing polygons with edges detected by image processing for refining the building segments. The experimental results showed that the RMSEs of building corners in X, Y and Z were ${\pm}$8.1㎝, ${\pm}$24.7㎝, ${\pm}$35.9㎝, respectively.

• The Korean Journal of Zoology
• /
• v.35 no.3
• /
• pp.295-307
• /
• 1992

In order to study the differentiation of the epithelial cells during the development of fetal rat lung tissue, histological changeB in organotypic culture and in vivo were examined. Light microscopy and scanning electron microscopy were used to analvre the histological change in rat lung from the 15th nary of gestation to the 111th nary after birth. In organotypic culture system, the pulmonary epithelial cell differentiation was studied by scanning electron microscopy. The results obtained from this study were as follows. 1. During deveiopment of lung, the glandular stage lasted from the Isth day to the lsth naut of gestation; the canalicular stage from the 17th nay to the 19th naut of gestation; the saccuiar stage from 20th nary to the birth. Alveolar stage was observed at the 3rd nary of postnatal rat lung. 2. In organotvpic culture of fetal rat lung cells organized alveolar-like structures resembling those of in uiuo state were observed on the gelatin matrix. In contrast with in vivo state, fetal lung cells formed group of type ll pneumocytes predominently along the contours of the matrix. These cells have large apical surface, short microvilli and secreted materials which may be sunactant. These results suggested that an orsanotypic culture retaining epithelial- -mesenchvmal relationships is appropriate culture model to study the pulmonary epithelial cell (especially type ll pneumocvte) differentation.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2007.11a
• /
• pp.1224-1230
• /
• 2007

In this study, a new modal test method is presented to evaluate vibration characteristic of the nano imprint stage system. Since it is difficult to measure vibration level without contacting the machine component, non contacting modal test method, laser scanning system is ultrared. Finite element analysis results are compared with the modal test results.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.8 no.3
• /
• pp.435-441
• /
• 1998

Li-SGICs as a anode of lithium ion battery were synthesized by high-pressure method as a function of the Li-contents. The characteristics of these prepared compounds were determined from the studies with X-ray diffraction method and differential scanning calorimeter (DSC) analysis. From the results of X-ray diffraction, it was found that the lower stage intercalation compounds were formed with increase of Li-contents. The mixed stages in these compounds were also observed. In the case of the $Li_{30;wt%}$-SGIC, the compounds in the stage 1 structure were formed predominantly, but the structure of only pure stage 1, due to the structural defect of synthetic graphite, was not observed. The enthalpy and entropy changes of the compounds could be obtained from the differential scanning calorimetric analysis results. From the results, it was found that exothermic and endothermic reactions of Li-SGICs are related to thermal stability of lithium between artificial graphite layers.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.12 no.1
• /
• pp.72-81
• /
• 1990

Because failure of microvascular flap grafting has sometimes been attributed to vascular obstruction in the anastomotic site, this study investigated the healing process after microvascular anastomoses. The healing process of anastomotic sites were observed by the use of the light and the scanning electron microscope after microvascular anastomoses of the right common carotid artery in rats. The experimental animals were sacrificed on the 4th day, 1st, 2nd, 4th and 6th week. Throughout the whole experimental period, arterial patency rate was 78% (11/14). At the early stage, it was possible to recognize histologically disappearance of endothelial cell and rupture of part of the media. Subintimal hyperplasia and the growth of media appeared around the suture line at the 2nd week. Endothelial cell regeneration occurred and the depth of vessel wall was normalized at the 4th week. By the scanning electron microscope, at the early stage, the anastomotic site was covered with many platelets, red blood cells, fibrins and macrophages. At the 4th week, the insertion site of the thread was completely covered with normal endothelial cells which were parallel to longitudinal axis of vessels and complete reendothelialization over the anastomotic site seemed to take about 6th week.

• Transactions of the Korean Society of Machine Tool Engineers
• /
• v.15 no.3
• /
• pp.111-119
• /
• 2006

The ultra-precision stage is demanded for some industrial fields such as semiconductor lithography, ultra-precision machining, and fabrication of nano structure. A new stage was developed for those applications in order to obtain nano meter resolution. This stage consists of symmetric double parallelogram mechanism using flexure hinges. The mechanical properties such as strength of the flexures and deformations along the applied force were analyzed using FEM. The stage is actuated by a piezoelectric actuator and its movement was measured by a ultra-precision linear encoder. In order to improve positioning performance, a PID controller was designed based on the identified second order transfer function. Experimental results showed that this stage could be positioned within below 5 nm resolution irrespective of hysteresis and creep by the controller.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.30 no.9 s.252
• /
• pp.1094-1101
• /
• 2006

Recently, a ultra-precision stage is widely used in the fields of the nano-technology, specially in AFMs(Atomic Force Microscope) and STMs(Scanning Tunneling Microscope). In this paper, the ultra-precision stage which consists of flexure hinges, piezoelectric actuator and ultra-precision linear encoder, is designed and developed. The system transfer function of the ultra-precision stage system was derived from the step responses of the system using system identification tool. A $H_{\infty}$ controller was designed using loop shaping method to have robustness for the system uncertainty and external disturbances. For the designed controller, simulations were performed and it was applied to the ultra-precision stage system. From the experimental results it was found that this stage could be controlled with less than 5nm resolution irrespective of hysteresis and creep.

• Journal of the Korean Institute of Telematics and Electronics B
• /
• v.31B no.7
• /
• pp.101-107
• /
• 1994

In this work a scanning capacitance microscopy(SCaM) by stage driving is proposed and presented some of the experimental results.SCaM is a microscope which scans a surface of materials mechanically in two or two point five dimensions by a capacitance probe with a few tenth $\mu\textrm{m}$ ize tip, and display images of the surface shape or capacitive distribution. The present target of the SCaM is 0.1$\mu\textrm{m}$ resolution power which exceeds that of optical microscope. This will become a powerful tool for inspecting ULSI pattern etched by X-ray biological data etc. The experimental system is composed based on a VHD video disk which captures the capacitance changes of the video disk surface and converts it into video signal.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2012.02a
• /
• pp.559-559
• /
• 2012

We developed a new scheme for the highly sensitive near-field scanning optical microscope (NSOM) by using a dithering sample stage rather than a dithering probe. In the proposed scheme, the sample is directly loaded on one prong surface of a dithering bare tuning fork. Gap control between probe and sample is performed by detecting the shear force between an immobile fiber probe and the dithering sample. In a conventional NSOM, the Q factor drastically decreases from 7783 to 1000 or even to 100 by attaching a probe to the tuning fork. In our proposed NSOM, on the contrary, the Q factor does not change significantly, 7783 to 7480, when the sample is loaded directly to the tuning fork instead of attaching a probe. Consequently, the graphene sheets that cannot be observed by a conventional NSOM were clearly observed by the proposed method with sub-nanometer vertical resolution due to the extremely high Q factor.