Hyun-Deok Kim

A Study on the Characteristics of Laser Deposition Surface and Cross-section for Metal Powder

In this study, we compared the physical and chemical properties evaluation for each size in the SUS316L metal powder produced by water atomization and gas atomization. and we analyzed the experimental data in order to find the basis of a suitable metal powder (SUS316L) for DED (Direct Energy Deposition) processing. Also it evaluated the properties of each layered surface and cross section according to the number of deposition and deposition speed. In the result of optical microscopy measurements, the metal powder by water atomization was the crack generated between the deposition layer, the deposition layer was poor quality. However, metal powder by gas atomization was obtained a relatively good deposition results than metal powder by water atomization.

Development of image error correction system for 3D optical microscope

Recently 3D optical microscope is developing to see micro details in three-dimensions. To see images of an optical microscope in three-dimensions, we mount two cameras on the optical microscope. Three-dimension images are created using by two images that are incoming image through the refractive mirror with eye piece lens and those are made by two cameras. In this time, because of optical design errors and deformation mechanism of an optical microscope, it makes the problem which is disconformity of images. This case cannot be made a three-dimensional image correctly. We have corrected the error-output image of 3D optical microscope and developed the system showing the correct three-dimensional image.

Evaluating ortho-photo production potentials based on UAV real-time geo-referencing points

Studies using unmanned aerial vehicle (UAV) are being actively conducted to obtain and apply spatial information. Spatial information based on orthophoto can be analyzed only when positional accuracy of these photos is high. To solve this problem, survey techniques, such as virtual reference station–real time kinematic (VRS–RTK) are used to create a ground control point (GCP), and geo-referencing is performed on the images. However, orthophoto based on non-fiducial points are generated in scenarios where spatial information is urgently required or in physical environments where GCPs are unlikely to be surveyed. In this method, a location error occurs and reduces the accuracy of orthophoto. In this study, a method that estimates GCPs using only measurement information using the UAV without a GCP survey and generates orthophoto based on those points, is proposed and its applicability is verified. 254 aerial photos were obtained using UAV. The location of six GCPs was estimated based on measurement information using UAV. Subsequently, the aerial photos and GCPs estimated based on the UAV measurement information were used to generate an orthophoto. This orthophoto was compared with those based on VRS–RTK GCPs and non-fiducial points in an error analysis. The analytic result indicates that the orthophoto based on the proposed method has an error that is 74.53% lower compared to that based on non-fiducial points. It is anticipated that the method proposed in this study to generate orthophoto based on information surveyed using the UAV can be effectively applied under physical environments where GCPs are unlikely to be established.

Development of the non-wearable system with FSR sensors for correction of sitting position

The purpose of our work is to develop a system that can detect and alarm the individuals sitting position of inactive period. Non-wearable sensor system based on FSR includes a H/W device for interfacing between a computer S/W that process sensing data and FSR module as a Sitting Mat. Pressure intensity of each sensing point on computer S/ W can be showned by color change and area expansion and we observe changes in the quantitative and qualitative. Our system has an edge in price competitiveness compared to the existing foreign system by reducing the number of FSR sensor array and improve the sensitivity of Load Measurements with computer S/W algorithm. In the future, it will continue to be developed smartphone apps to check real-time alerts with transmitting data over the bluetooth interface. and we will be expected to develope FSR sensors with durability and ductility by performing clinical trials with Office workers who sit for a long time.

Align-free Micro-optic Mach-Zehnder Interferometric Filter

A novel alignment-free micro-optic MZI filter has been demonstrated. The filter is composed of two fiber-pigtailed collimators and a beam-splittingplate with a periodically etched stripe pattern. We fabricated the plate through a standard lithographic formulation process by using a pyrex substrate glass with SU-8 resist coating on its one of the surfaces. The maximum insertion loss of the implemented filter was less than 2 dB over 1000 nm to 1600 nm and the extinction ratio was larger than 33 dB. The measured PDL within the 3-dB pass band of the filter was less than 0.15dB and the maximum extinction ratio variation was less than 2 dB even when the worst alignment error occured.