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Variable Shape and Stiffness Feedback System for VR Gloves Using SMA Textile Actuator
SangUn Kim,SeongMo Gu,Jooyong Kim 한국섬유공학회 2022 Fibers and polymers Vol.23 No.3
Currently, when direct human contact is limited owing to the coronavirus era, virtual reality systems are atechnology that enables interaction without spatial restrictions. In this study, a system capable of feedbacking variousshapes and stiffness when touching an object in virtual reality was conceived using the SMA textile actuator, which is ashape memory alloy (SMA) that remembers by training at 500 °C for 15 min with training tools that fixed shapes of SMAorigin, and it returns to the shape at 40.13 °C or higher by Joule heating. SMA textile actuators were fabricated by zigzagstitching with 0.5 mm intervals. Various shapes were feedback because the SMA textile actuators on gloves interfere withthe movement of the finger joints and the feedback force levels of stiffness are divided based on the number of actuatorsoperating, and feedback is possible in three levels. We verified shape feedback that matches sensing points that are placedon the virtual finger joints created by Unity 3D, which is a software for making virtual reality to feedback points on VRgloves with three events using Unity 3D logs. We measured the forces of each feedback force level with SMA diameters 0.4of 0.6 mm. The results showed 2.3 N with 0.6 mm; however, owing to its rigidity, 0.5 mm SMA textile actuator isappropriate. Finally, by implementing one feedback point of the VR gloves, we verified the operation of the system from theoccurrence of an event by touching an object in virtual reality to control the feedback force level through the MCU andrelay.
진동형 히트파이프 흡열판이 결합된 하이브리드 태양광/열 시스템
김창희(Changhee Kim),전동환(Donghwan Jeon),공상운(Sangun Kong),김종수(Jongsu Kim) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.5
The electricity conversion-efficiency of solar cell for commercial application is about 6-15%. More than 85% of the incoming solar energy is either reflected or absorbed as heat energy. Consequently, the working temperature of the photovoltaic cells increases considerably after prolonged operations and the cell's efficiency drops significantly. PV/T refers to the integration of a PV module and a solar thermal collector in a single piece of equipment. By cooling the PV module with a fluid steam like air or water, the electricity yield can be improved. At the same time, the heat pick-up by the fluid can be to support space heating or service hot-water systems. In this study, a pulsating heat pipe solar heat collector was combined with single-crystal silicon photovoltaic cell in hybrid energy-generating unit that simultaneously produced low temperature heat and heat and electricity. This experiment was investigating thermal and electrical efficiency for evaluation of a PV/T system.
Kullback-Leibler Information of Consecutive Order Statistics
Kim, Ilmun,Park, Sangun The Korean Statistical Society 2015 Communications for statistical applications and me Vol.22 No.5
A calculation of the Kullback-Leibler information of consecutive order statistics is complicated because it depends on a multi-dimensional integral. Park (2014) discussed a representation of the Kullback-Leibler information of the first r order statistics in terms of the hazard function and simplified the r-fold integral to a single integral. In this paper, we first express the Kullback-Leibler information in terms of the reversed hazard function. Then we establish a generalized result of Park (2014) to an arbitrary consecutive order statistics. We derive a single integral form of the Kullback-Leibler information of an arbitrary block of order statistics; in addition, its relation to the Fisher information of order statistics is discussed with numerical examples provided.