• Current Optics and Photonics
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• v.3 no.5
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• pp.374-381
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• 2019

This study examined a method for designing the optical cavity of a non-dispersive infrared gas detector. The infrared gas detector requires an optical cavity design to lengthen the ray path. However, the optical cavity with multiple reflecting surfaces has off-axis aberration due to the characteristics of the reflecting optical system. The rays were parallelized by using the off-axis parabolic mirror to easily increase the ray path and eliminate off-axis aberration so that the rays are admitted to the effective area of the infrared detector uniformly. A prototype of an infrared gas detector was produced with the designed optical cavity to confirm the performance.

• Current Optics and Photonics
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• v.5 no.4
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• pp.402-408
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• 2021

An off-axis system refers to an optical system in which the optical axis and normal vector at the vertex of each surface do not match. The most important specification in an optical system is its focal length. Among the various methods for measuring the focal length, the most suitable method for the off-axis system is the method that adopts magnification. However, head-mounted display (HMD) optics must be measured while considering the virtual image distance, which is not infinity owing to product characteristics. For the virtual image distance, a camera with a focusing function was used. By measuring HMD optics via this magnification method, the error generated in this measurement was 0.68% of the HMD's focal length, which is within the 1%-3% range of the conventionally permitted design error for the focal length allowed at the optical design stage. Therefore, it can be verified that the measurement accuracy of the method proposed in this study is sufficiently feasible in practice.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.10
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• pp.12-17
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• 2009

• Journal of Electrochemical Science and Technology
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• v.3 no.1
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• pp.29-34
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• 2012

The structural changes of $Li_{1-x}Ni_{0.5}Co_{0.2}Mn_{0.3}O_2$ cathode material for lithium ion battery during the first charge was investigated in comparison with $Li_{1-x}Ni_{0.8}Co_{0.15}Al_{0.05}O_2$ using a synchrotron based in situ X-ray diffraction technique. The structural changes of these two cathode materials show similar trend during first charge: an expansion along the c-axis of the unit cell with contractions along the a- and b-axis during the early stage of charge and a major contraction along the c-axis with slight expansions along the a- and b-axis near the end of charge at high voltage limit. In $Li_{1-x}Ni_{0.5}Co_{0.2}Mn_{0.3}O_2$ cathode, however, the initial unit cell volume of H2 phase is bigger than that of H1 phase since the c-axis undergo large expansion while a- and b- axis shrink slightly. The change in the unit cell volume for $Li_{1-x}Ni_{0.5}Co_{0.2}Mn_{0.3}O_2$ during charge is smaller than that of $Li_{1-x}Ni_{0.8}Co_{0.15}Al_{0.05}O_2$. This smaller change in unit cell volume may give the $Li_{1-x}Ni_{0.5}Co_{0.2}Mn_{0.3}O_2$ cathode material a better structural reversibility for a long cycling life.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.10
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• pp.3789-3793
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• 2010

To investigate accuracy of graduated scale of schematic retinoscope training eye(schematic eye) and induced effect when measured at off-axis from visual axis. Two skilled retinoscopist measured refractive power using retinoscope in random order. Seven schematic eyes from a single manufacturer were recruited and set to mark +4.00 to -6 diopter(+4, +3, +2, +1, 0, -1, -2, -3, -4, -5, -6). After introducing +2.00 diopter trial lens(50cm working lens), neutral distance was measured at 180 degree to estimate accuracy of scale, and refractive power measured at 0, 5, 10, 15 and 20 degree off-axis to see if any error was induced. According to the results measured by two specialists, in six of seven schematic eye, scale setting varied (p<0.05) and measured refractive power at 5, 10, 15 and 20 degree off-axis from visual axis were $-0.13{\pm}0.06$, $-0.29{\pm}0.06$, $-0.58{\pm}0.11$, and $-0.83{\pm}0.16$ diopter respectively. In some schematic eye, scale graduated on the schematic eye and scale measured by retinoscopy could be different and if retinoscopy is performed off-axis from visual axis, any measuring error can be caused.

• The Journal of the Korea Contents Association
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• v.15 no.11
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• pp.10-17
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• 2015

Emotional computer that you want to study in a regular number change is the continuing sensitivity. Emotional Computing manner the sensibilities numbered and emotions were running through the trees. Emotional assessment of emotional sensibility computing was used as the coordinates of the key effects of the James A. Russell (Core Affect). Emotional tree runs purpose was to verify the correlation of sensitivity and emotion computing tree. Emotional tree attributes experiment color, brightness, saturation was configured with. When 50% brightness increase, about pleasure (X-axis) has increased by 10.49 points. Brightness 50%, GREEN 50% increase in the degree of pleasure (X-axis) of 10.49 points, tone (Y axis) has increased by 15.85 points. Brightness 50%, GREEN 50% increase in the degree of pleasure (X-axis) of 10.49 points, tone (Y axis) has increased by 15.85 points. Brightness 50% of the free-extent (X-axis), BLUE 50% when the tone (Y axis), pleasure extent (X-axis) of 10.49 points, tone (Y axis) as much as 14.65 points sensibilities have changed. When representatives emotions size changes have increased 50% brightness, color RED 50%, increased 5.4% Emotional excitement, emotion depressed declined -4.2%. 50% brightness, color GREEN 50% increase in emotional excitement had increased to 8.6%, declined by -5.5% this melancholy sensibility. Representative emotion and emotional changes increase or decrease the size of the emotional attributes were analyzed by quantitative methods. After the happy emotions number is needed to study more similar to the human emotion through the execution of the video image emotion emotional tree computing.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.5 s.170
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• pp.197-204
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• 2005

In this study, ground reaction force(GRF), absolute symmetry index(ASI) and coefficient of variation(CV) of fixed, single-axis and multi-axis prosthetic ankle assemblies were investigated to show the biomechanical evaluation for above knee amputees. In the experiments, 37 normal male volunteers, two male and two female AK amputees were tested with fixed, single-axis and multi-axis prosthetic ankle assembly. A gait analysis was carried out to derive the ratio of GRF to weight as the percentage of total stance phase for ten points. The results showed that fixed-axis ankle was superior to the other two ankle assemblies for the characteristic of forwarding and breaking forces. Multi-axis ankle was relatively superior to the other two ankle assemblies for gait balancing and movement of the center for mass. single-axis ankle was relatively superior to the other two ankle assemblies for CV and ASI of GRF.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.568-571
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• 2004

This paper presents an efficient 5-axis roughing method for centrifugal impeller. The efficient roughing is minimization of cutting time through minimizing tool tilting & rotating motions. Roughing tool path plan consists of the three steps. First, machining areas are divided into sub cutting regions using ruling lines. The biggest tool diameter is, then, determined for each region. Finally, tool paths are generated after fixing the tilting and rotating axis of 5-axis machine. Experimental results showed that the proposed roughing plan considering the divided machining regions is more efficient than the conventional methods.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.11a
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• pp.33-34
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• 2008

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.11a
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• pp.345-346
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• 2008