• Journal of Korea Multimedia Society
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• v.20 no.8
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• pp.1291-1298
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• 2017

Optical coherence tomography (OCT) is the most common medical imaging device with the ability to image the retina in eyes at micrometer resolution and to visualize the pathological indicators of many retinal diseases such as Age-Related Macular Degeneration (AMD) and diabetic retinopathy. Accordingly, there have been research activities to analyze and process OCT images to identify those indicators and make medical decisions based on the findings. In this paper, we use a deep convolutional neural network for analysis of OCT volume data to distinguish AMD from normal patients. We propose a novel approach where images in each OCT volume are grouped together into sub-volumes and the network is trained by those sub-volumes instead of individual images. We conducted an experiment using public data set to evaluate the performance of the proposed approach. The experiment confirmed performance improvement of our approach over the traditional image-by-image training approach.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.9
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• pp.1094-1102
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• 2011

Recent trends for the miniaturization and weight reduction of portable electronic parts is the use of subminiature components. Assembly of the miniaturized components requires subminiature screws of which pitch sizes are in a micrometer scale. To produce such a subminiature screw with high precision threads, not only a precision forming technology but also high-precision measurement technique is required. In the present work, a vision inspection system is developed to measure the thread profile of a subminiature screw. Optical simulation based on a ray tracing method is used to design and analyze the optical system of the vision inspection apparatus. Through this simulation, optical performance of the developed vision inspection system is optimized. The image processing algorithm for the precision screw inspection is also discussed.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.20 no.4
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• pp.446-451
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• 2011

Recent trends for the miniaturization and weight reduction of portable electronic parts have driven uses of subminiature components. Assembly of the miniaturized components requires subminiature screws of which pitch sizes are micrometer scale. To produce such subminiature screws with high precision threads, not only a precision forming technology but also a high-precision measurement technology is required. The present study covers the development of a vision inspection system for precision screws for the automatic measurement of subminiature screws with high speed and reliability. In this study, the feeding unit that transfers the subminiature screws to the inspection unit is investigated through finite element(FE) analysis. The vibration characteristics of the feeding unit are predicted through FE analyses, from which we can determine whether the subminiature screw can be stably fed into the inspection unit or not. The effects of several design parameters on the vibration characteristics are also discussed.

• Journal of the Korean Society for Precision Engineering
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• v.31 no.9
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• pp.839-846
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• 2014

Recent trends in the miniaturization and weight reduction of portable electronic parts have driven the use of subminiature screws with a micrometer-scale pitch. As both screw length and pitch decrease in subminiature screws, the resulting clamping force becomes diminishes. In this work, Finite element (FE) analysis is performed to evaluate clamping force of a screw assembly, with a comparison with experimental result. To improve clamping force of subminiature screws, a new screw design is considered by modifying screw thread angle: the thread angle is varied as an asymmetric way unlike the conventional symmetric thread angle. FE analyses are then performed to compare the clamping characteristics of each subminiature screw with different thread angle. The effect of thread angles on the clamping force is then discussed in terms of structural safety for both positive and negative screws.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.15 no.4
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• pp.44-48
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• 2006

Recently, demand the ultra precision product which is increasing rapidly is used extensively frontier industry field such as semi-conductor, computer, aerospace, precision machine. Ultra precision processing is the portion that is very needed to NT in the field of mechanical engineering. The latest date, together with radical advancement of electronic and photonics industry, necessity of ultra precision processing is on the increase for the manufacture of various kernel parts those are connected with these industrial fields. Specially, require motion accuracy of high resolution of nm order in stroke of hundreds millimeters according as diameter of processing object great and processing accuracy rises. In this case ,the response speed absolute delay because inertial mass of moving part is very large. Therefore, real time motion error compensation becomes very hardly. In this paper, we used ultra precision cutting unit(UPCU) to cope such problem. a UPCU is designed and tested to obtain sub-micrometer from accuracy in diamond turning of flat surfaces. The thermal growth spindle error is compensated for real time using a UPCU driven by piezoelectric actuator along with a laser encoder displacement sensor.

• Membrane and Water Treatment
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• v.13 no.6
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• pp.313-320
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• 2022

Theoretical calculation results are presented for the enhancement of the water mass flow rate through the hydrophobic micro/nano pores in the membrane respectively on the micrometer and nanometer scales. The water-pore wall interfacial slippage is considered. When the pore diameter is critically low (less than 1.82nm), the water flow in the nanopore is non-continuum and described by the nanoscale flow equation; Otherwise, the water flow is essentially multiscale consisting of both the adsorbed boundary layer flow and the intermediate continuum water flow, and it is described by the multiscale flow equation. For no wall slippage, the calculated water flow rate through the pore is very close to the classical hydrodynamic theory calculation if the pore diameter (d) is larger than 1.0nm, however it is considerably smaller than the conventional calculation if d is less than 1.0nm because of the non-continuum effect of the water film. When the driving power loss on the pore is larger than the critical value, the wall slippage occurs, and it results in the different scales of the enhancement of the water flow rate through the pore which are strongly dependent on both the pore diameter and the driving power loss on the pore. Both the pressure drop and the critical power loss on the pore for starting the wall slippage are also strongly dependent on the pore diameter.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.8
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• pp.584-592
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• 2012

Room temperature powder spray in vacuum process, so called Aerosol deposition (AD) is a room temperature (RT) process to fabricate thick and dense ceramic films, based on collision of solid ceramic particles. This technique can provide crack-free dense thin and thick films with thicknesses ranging from sub micrometer to several hundred micrometers with very fast deposition rates at RT. In addition, this technique is using solid particles to form the ceramic films at RT, thus there is few limitation of the substrate and easy to control the compositions of the films. In this article, we review the progress made in synthesis of piezoelectric thin/thick films, multi-layer structures, NTC thermistor thin/thick films, oxide electrode thin films for actuators or sensor applications by AD at Korea Institute of Materials Science (KIMS) during the last 4 years.

• Journal of the Institute of Convergence Signal Processing
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• v.20 no.1
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• pp.16-23
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• 2019

Fine particulate matter known as PM 2.5 refers to the atmospheric particulate matter that has a diameter less than 2.5 micrometer identified as dangerous element for human health and its concentration can provide us a clear picture about air dust concentration. Humans stay indoor almost 90% of their life time and also there is no official indoor dust concentration data, so our study is focused on measuring the indoor air quality. Indoor dust data monitoring is very important in hospital environments beside that other places can also be considered for monitoring like classrooms, cements factories, computer server rooms, petrochemical storage etc. In this paper, visible light communication system is proposed by Manchester encoding technique for electromagnetic interference (EMI)-free indoor dust monitoring. Important indoor environment information like dust concentration is transferred by visible light channel in wide range. An average voltage-tracking technique is utilized for robust light detection to eliminate ambient light and low-frequency noise. The incoming light is recognized by a photo diode and are simultaneously processed by a receiver micro-controller. We can monitor indoor air quality in real-time and can take necessary action according to the result.

• Journal of Electrochemical Science and Technology
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• v.11 no.3
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• pp.273-281
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• 2020

Constructing and making highly active and stable nanostructured Pt-based catalysts with ultralow Pt loading are still electrifying for electrochemical applications such as water electrolysis and fuel cells. In this study, MoO₃ ribbons (RBs) of few micrometer in length is successfully synthesized via hydrothermal synthesis. Subsequently, 3-dimentional (3D)-silicate layer for about 10 to 15 nm is introduced via chemical deposition onto the pre-formed MoO₃ RBs; to setup the platform for Pt metaldots (MDs) deposition. In comparison with the bare MoO₃ RBs, the MoO₃-Si has served as a efficient solid-support for stabilizing and accommodating the uniform deposition of sub-2 nm Pt MDs. Such a structural design would effectively assist in improving the electronic conductivity of a fabricated MoO₃-Si-Pt catalyst towards MOR; the interfaced, porous and 3D silicate layer has assisted in an efficient mass transport and quenching the poisonous CO_ads species leading to a significant electrocatalytic performance for MOR in alkaline medium. Uniformly decorated, sub-2 nm sized Pt MDs has synergistically oxidized the MeOH in association with the MoO₃-Si solid-support hence, synergistic catalytic activity has been achieved. Present facile approach can be extended for fabricating variety of highly efficient Metal Oxide-Metal Nanocomposite for energy harvesting applications.

• Journal of the Korean Society for Precision Engineering
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• v.7 no.4
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• pp.23-28
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• 1990

This study is to investigate the magnitude, direction and distribution of residual stresses in surface ground plate according to working conditions. The specimens were made of structural carbon steel and were machined in various grinding conditions. These were divided in two groups; heat-treated materials and non-heat-treated materials. In each working condition, let the ground specimen generate displacements using deflection-etching techniques. At the same time, these displacements were precisely measured with electronic micrometer. Through the relation formula between the plane stress and strain, which was derived using these measured data, the values of residual stress are calculated, and the results are analyzed. These results are as follows : 1. According to the working conditions in this experiment, it can be seen that the distribution of residual stress generally had same trend and the maximum residual stress remained in 20~30 ((${\mu}m$) beneath the surface. 2. It is observed that compressive residual stress changes into tensile stress in 5~20 (${\mu}m$) beneath the surface. It is suggested that such phenomenon is originated from the friction effect in grinding process. 3. As the hardness increases by the heat treatment, residual stress increases. 4. As the fatigue strength increases by the compressive residual stress, it is desirable that the dowm feed and table feed reduce. 5. It can be seen that the more great the down feed and table feed increase, the more close the changing point, where the stress changed from compressive to tensile, is colse to the surface. This is due to the resultant effects of the grinding temperature and resistence are larger than the effect of the friction.