• Title/Summary/Keyword: Self sensing

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Design of Fuse Elements of Current Sensing Type Protection Device for Portable Secondary Battery Protection System (휴대용 이차전지 보호 시스템용 전류 감지 동작형 보호소자의 퓨즈 가용체 설계)

  • Kang, Chang-Yong;Kim, Eun-Min
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.67 no.12
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    • pp.1619-1625
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    • 2018
  • Portable electronic devices secondary batteries can cause fire and explosion due to micro-current change in addition to the situation of short-circuit inrush current, safety can not be secured with a general operation limited current fuse. Therefore, in secondary battery, it is necessary for the protector to satisfy both the limit current type operation in the open-short-circuit inrush current and the current detection operation characteristic in the micro current change situation and for this operation, a fuse for the current detection type secondary battery protection circuit can be applied. The purpose of this study is to design a protection device that operates stably in the hazardous situation of small capacity secondary battery for portable electronic devices through the design of low melting fuse elements alloy of sensing type fuse and secures stability in abnormal current state. As a result of the experiment, I-T and V-T operation characteristics are satisfied in a the design of the alloy of the current sensing type self-contained low melting point fuse and the resistance of the heating resistor. It is confirmed that it can prevent accidents of short circuit over-current and micro current change of secondary battery.

Learning Style and Self-directed Learning of Nursing Students at One University (일개 간호대학생의 학습유형과 자기주도적 학습)

  • Park, Jee-Won;Bang, Kyung-Sook
    • Perspectives in Nursing Science
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    • v.7 no.1
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    • pp.36-42
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    • 2010
  • Purpose: This study was done to identify the preferences for learning style and the degree of self-directed learning and influencing factors on it among nursing students working on a Bachelor of Science in a nursing program at Suwon. Methods: The study sample included 156 nursing students. A self-report questionnaire was used to assess the data. The data was analyzed using the SPSS/WIN program for descriptive and inferential statistics. Results: Most of the students preferred lectures rather than discussion or team projects as a teaching method. Students preferred deliberating, sensing, and the use of visuals for their learning style. In addition, they favored sequential learning over comprehensive learning. Self directed learning had better outcomes in 3rd and 4th year students than 1st or 2nd year students. Additionally, active learners and high achievers who had a good GPA showed higher self directed learning than the others. Conclusion: In order to maximize students' self-directed learning, study guidance will be necessary for freshmen and for some who experience difficulties in studying nursing courses. Nursing faculty members should pay close attention to facilitate student's self directed learning, and encourage more discussions in the classes.

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Development of Self-Actuated Shutdown System Using Curie Point Electromagnet

  • Kim, Tae-Ryong;Park, Jin-Ho
    • Nuclear Engineering and Technology
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    • v.31 no.6
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    • pp.1-7
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    • 1999
  • An innovative concept for a passive reactor shutdown system, so called self-actuated shutdown system(SASS), is inevitably required for the inherent safety in liquid metal reactor, which is designed with the totally different concept from the usual reactor shutdown system in LWR. SASS using Curie point electromagnet(CPEM) was selected as the passive reactor shutdown system for KALIMER (Korea Advanced Liquid MEtal Reactor). A mock-up of the SASS was designed, fabricated and tested. From the test it was confirmed that the mockup was self-actuated at the Curie point of the temperature sensing material used in the mockup. An articulated control rod was also fabricated and assembled with the CPEM to confirm that the control rod can be inserted into core even when the control rod guide tube is deformed due to earthquake. The operability of SASS in the actual sodium environment should be confirmed in the future. All the design and test data will be applied to the KALIMER design.

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Self-powered Sensors based on Piezoelectric Nanogenerators

  • Rubab, Najaf;Kim, Sang-Woo
    • Journal of Sensor Science and Technology
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    • v.31 no.5
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    • pp.293-300
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    • 2022
  • Flexible, wearable, and implantable electronic sensors have started to gain popularity in improving the quality of life of sick and healthy people, shifting the future paradigm with high sensitivity. However, conventional technologies with a limited lifespan occasionally limit their continued usage, resulting in a high cost. In addition, traditional battery technologies with a short lifespan frequently limit operation, resulting in a substantial challenge to their growth. Subsequently, utilizing human biomechanical energy is extensively preferred motion for biologically integrated, self-powered, functioning devices. Ideally suited for this purpose are piezoelectric energy harvesters. To convert mechanical energy into electrical energy, devices must be mechanically flexible and stretchable to implant or attach to the highly deformable tissues of the body. A systematic analysis of piezoelectric nanogenerators (PENGs) for personalized healthcare is provided in this article. This article briefly overviews PENGs as self-powered sensor devices for energy harvesting, sensing, physiological motion, and healthcare.

3-D Hetero-Integration Technologies for Multifunctional Convergence Systems

  • Lee, Kang-Wook
    • Journal of the Microelectronics and Packaging Society
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    • v.22 no.2
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    • pp.11-19
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    • 2015
  • Since CMOS device scaling has stalled, three-dimensional (3-D) integration allows extending Moore's law to ever high density, higher functionality, higher performance, and more diversed materials and devices to be integrated with lower cost. 3-D integration has many benefits such as increased multi-functionality, increased performance, increased data bandwidth, reduced power, small form factor, reduced packaging volume, because it vertically stacks multiple materials, technologies, and functional components such as processor, memory, sensors, logic, analog, and power ICs into one stacked chip. Anticipated applications start with memory, handheld devices, and high-performance computers and especially extend to multifunctional convengence systems such as cloud networking for internet of things, exascale computing for big data server, electrical vehicle system for future automotive, radioactivity safety system, energy harvesting system and, wireless implantable medical system by flexible heterogeneous integrations involving CMOS, MEMS, sensors and photonic circuits. However, heterogeneous integration of different functional devices has many technical challenges owing to various types of size, thickness, and substrate of different functional devices, because they were fabricated by different technologies. This paper describes new 3-D heterogeneous integration technologies of chip self-assembling stacking and 3-D heterogeneous opto-electronics integration, backside TSV fabrication developed by Tohoku University for multifunctional convergence systems. The paper introduce a high speed sensing, highly parallel processing image sensor system comprising a 3-D stacked image sensor with extremely fast signal sensing and processing speed and a 3-D stacked microprocessor with a self-test and self-repair function for autonomous driving assist fabricated by 3-D heterogeneous integration technologies.

Combining smart materials for enhancing intelligent systems: initial studies, success cases and research trends

  • Diaz Lantada, A.;Lafont Morgado, P.;Munoz-Guijosa, J.M.;Munoz Sanz, J.L.;Echavarri Otero, J.;Chacon Tanarro, E.;De la Guerra Ochoa, E.
    • Smart Structures and Systems
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    • v.14 no.4
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    • pp.517-539
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    • 2014
  • The combined use of smart materials, complementing each others' characteristics and resulting in devices with optimised features, is providing new solutions in many industries. The use of ingenious combinations of smart materials has led to improvements in actuation speed and force, signal-to-noise ratio, sensor precision and unique capabilities such as self-sensing self-healing systems and energy autonomy. This may all give rise to a revival for numerous families of smart materials, for which application proposals had already reached a stationary situation. It may also provide the boost needed for the definitive industrial success of many others. This study focuses on reviewing the proposals, preliminary studies and success cases related to combining smart materials to obtain multifunctional, improved systems. It also examines the most outstanding applications and fields for the combined use of these smart materials. We will also discuss related study areas which warrant further research for the development of novel approaches for demanding applications.

Interfacial Durability and Electrical Properties of CNT or ITO/PVDF Nanocomposites for Self-Sensor and Micro Actuator (자체-센서와 미세 작동기를 위한 CNT/PVDF 및 ITO/PVDF 나노복합재료의 전기적 및 계면 내구성 비교 평가)

  • Gu, Ga-Young;Wang, Zuo-Jia;Kwon, Dong-Jun;Park, Joung-Man
    • Composites Research
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    • v.24 no.6
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    • pp.12-17
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    • 2011
  • Interfacial durability and electrical properties of CNT or ITO coated PVDF nanocomposites were investigated for self-sensor and micro actuator applications. Electrical resistivity of nanocomposites for the durability on interfacial adhesion was measured using four points method via fatigue test under cyclic loading. CNT/PVDF nanocomposite exhibited lower electrical resistivity and good self-sensing performance due to inherent electrical property. Durability on the interfacial adhesion was good for both CNT and ITO/PVDF nanocomposites. With static contact angle measurement, surface energy, work of adhesion, and spreading coefficient between either CNT or ITO and PVDF were obtained to verify the correlation with interfacial adhesion durability. The optimum actuation performance of CNT or ITO coated PVDF specimen was measured by the displacement change using laser displacement sensor with changing frequency and voltage. The displacement of actuated nanocomposites decreased with increasing frequency, whereas the displacement increased with voltage increment. Due to nanostructure and inherent electrical properties, CNT/PVDF nanocomposite exhibited better performance as self-sensor and micro actuator than ITO/PVDF case.

Self-Sensing of Single Carbon Fiber/Carbon Nanotube-Epoxy Composites Using Electro-Micromechanical Techniques and Acoustic Emission (전기적-미세역학시험법과 음향방출을 이용한 단일 탄소섬유/탄소나노튜브-에폭시 나노복합재료의 자체-감지능)

  • Park, Joung-Man;Jang, Jung-Hoon;Wang, Zuo-Jia;Kwon, Dong-Jun;Park, Jong-Kyu;Lee, Woo-Il
    • Journal of the Korean Society for Nondestructive Testing
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    • v.30 no.5
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    • pp.411-422
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    • 2010
  • Self-sensing on micro-failure, dispersion degree and relating properties, of carbon nanotube(CNT)/epoxy composites, were investigated using wettability, electro-micromechanical technique with acoustic emission(AE). Specimens were prepared from neat epoxy as well as composites with untreated and acid-treated CNT. Degree of dispersion was evaluated comparatively by measuring volumetric electrical resistivity and its standard deviation. Apparent modulus containing the stress transfer was higher for acid-treated CNT composite than for the untreated case. Applied cyclic loading responded well for a single carbon fiber/CNT-epoxy composite by the change in contact resistivity. The interfacial shear strength between a single carbon fiber and CNT-epoxy, determined in a fiber pullout test, was lower than that between a single carbon fiber and neat epoxy. Regarding on micro-damage sensing using electrical resistivity measurement with AE, the stepwise increment in electrical resistivity was observed for a single carbon fiber/CNT -epoxy composite. On the other hand, electrical resistivity increased infinitely right after the first carbon fiber breaks for a single carbon fiber/neat epoxy composite. The occurrence of AE events of added CNT composites was much higher than the neat epoxy case, due to micro failure at the interfaces by added CNTs.

Effect of Loading Rate on Self-stress Sensing Capacity of the Smart UHPC (하중 속도가 Smart UHPC의 자가 응력 감지 성능에 미치는 영향)

  • Lee, Seon Yeol;Kim, Min Kyoung;Kim, Dong Joo
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.22 no.5
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    • pp.81-88
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    • 2021
  • Structural health monitoring (SHM) systems have attracted considerable interest owing to the frequent earthquakes over the last decade. Smart concrete is a technology that can analyze the state of structures based on their electro-mechanical behavior. On the other hand, most research on the self-sensing response of smart concrete generally investigated the electro-mechanical behavior of smart concrete under a static loading rate, even though the loading rate under an earthquake would be much faster than the static rate. Thus, this study evaluated the electro-mechanical behavior of smart ultra-high-performance concrete (S-UHPC) at three different loading rates (1, 4, and 8 mm/min) using a Universal Testing Machine (UTM). The stress-sensitive coefficient (SC) at the maximum compressive strength of S-UHPC was -0.140 %/MPa based on a loading rate of 1 mm/min but decreased by 42.8% and 72.7% as the loading rate was increased to 4 and 8 mm/min, respectively. Although the sensing capability of S-UHPC decreased with increased load speed due to the reduced deformation of conductive materials and increased microcrack, it was available for SHM systems for earthquake detection in structures.