Disk-based triboelectric nanogenerator operated by rotational force converted from linear force by a gear system

Tcho, Il-Woong,Jeon, Seung-Bae,Park, Sang-Jae,Kim, Weon-Guk,Jin, Ik Kyeong,Han, Joon-Kyu,Kim, Daewon,Choi, Yang-Kyu Elsevier 2018 Nano energy Vol.50 No.-

<P><B>Abstract</B></P> <P>A triboelectric nanogenerator (TENG) is an energy harvester which converts ambient mechanical energy into electrical energy. A disk-based rotational TENG converts rotational mechanical energy into electrical energy with advantages over a vertical contact-separation based TENG. Since the disk-based TENG operates in grating-based sliding mode, its electrical output is advantageous in terms of prolonged continuous energy harvesting. However, rotational mechanical energy is less abundant than linear mechanical energy in typical environments. In this work, a new disk-based TENG which converts linear mechanical energy into electrical energy through the use of a gear system (linear-to-rotational TENG, LR-TENG) was fabricated as an experimental device. A TENG based on a vertical contact-separation mode (V-TENG), composed of identical triboelectric materials, was also fabricated as a control device. Here, it is experimentally demonstrated that the electrical output of the LR-TENG was superior to that of the V-TENG at the same magnitude of applied force and at an identical level of applied mechanical energy, as the surface charge density of the LR-TENG is much greater than that of the V-TENG. The LR-TENG can effectively provide power to numerous small electronic devices. Examples include charging a commercial capacitor and lighting commercial LEDs.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A disk-based rotational TENG operated by rotational force converted from linear force by a gear system, is demonstrated. </LI> <LI> Linear mechanical energy is more abundant than rotational mechanical energy in our environment. </LI> <LI> The electrical output of this linear-to-rotational TENG was superior to that of the vertical contact-separation TENG. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

A mononuclear nonheme cobalt(<small>III</small>)–hydroperoxide complex with an amphoteric reactivity in electrophilic and nucleophilic oxidative reactions

Tcho, Woon-Young,Wang, Bin,Lee, Yong-Min,Cho, Kyung-Bin,Shearer, Jason,Nam, Wonwoo The Royal Society of Chemistry 2016 Dalton Transactions Vol.45 No.37

<P>A mononuclear nonheme cobalt(III)-hydroperoxide complex bearing a tetramethylated cyclam ligand, [(12-TMC)Co-III(OOH)](2+), was synthesized and characterized spectroscopically and computationally; the cobalt(III)-hydroperoxide complex exhibited an amphoteric reactivity in electrophilic and nucleophilic oxidative reactions.</P>

Surface structural analysis of a friction layer for a triboelectric nanogenerator

Tcho, Il-Woong,Kim, Weon-Guk,Jeon, Seung-Bae,Park, Sang-Jae,Lee, Boung Ju,Bae, Hee-Kyoung,Kim, Daewon,Choi, Yang-Kyu Elsevier 2017 Nano energy Vol.42 No.-

<P><B>Abstract</B></P> <P>A triboelectric nanogenerator (TENG) is a promising type of energy harvester which converts ambient mechanical energy into electrical energy efficiently as part of the effort to overcome the energy depletion issue. To enhance the electrical output of the TENGs, the surface morphology is intentionally created on the surface of a friction layer of these harvesters. In this work, the shape dependency of the geometric morphology of a TENG, in terms of the electrical output, force sensitivity, and durability, is investigated by measurements and simulations with the aid of ANSYS. A well-ordered pillar-shaped and dome-shaped nanostructure was created on polydimethylsiloxane (PDMS), which is commonly used as a friction layer in TENGs. It was found here that the TENG with dome-shaped PDMS (DP-TENG) showed greater force sensitivity than the TENG with pillar-shaped PDMS (PP-TENG). However, the PP-TENG was found to be more durable than the DP-TENG. These results stem from the fact that the dome-shaped nanostructure will deform more easily than the pillar-shaped nanostructure. This study suggests a guideline for the structural engineering of the surface morphology of the friction layer with the consideration of the geometric shape to maximize the important properties of the TENGs.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Pillar and dome shaped nanostructures are created on polydimethylsiloxane (PDMS). </LI> <LI> Force sensitivity and durability of pillar and dome shaped PDMS TENG are investigated. </LI> <LI> This study suggests a guideline for the surface engineering of the friction layer. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

The Dragon in the Buddhist Korean Temples

Hye-young Tcho 동국대학교 불교학술원 2007 International Journal of Buddhist Thought & Cultur Vol.8 No.-

The dragon is a case of a remarkable integration of Buddhism in different cultures. In the Indian Buddhism, we find nāgas instead of dragons. The nāga is considered as the symbol of the renewal of life and fecundity. And Ś2kyamuni reached enlightenment at Bodhgay2, N2ga King became the first creature to receive the Buddha’s teaching. When Buddhism reached China, the n2ga were replaced with the dragons. All these gave to the dragon the status of a superior authority in the Chinese culture. Afterwards, the Buddhist dragon followed his own way in Asian countries. Such is the case in Korea where the belief in the dragon flourished in the spiritual, artistic and literary fields. After the adoption of Buddhism, the dragon became the most important divinity of Korea and the object of popular belief all along its history. The Korean temples do show the important role the dragon plays in the Korean Buddhist faith. We can find that kind of believe in Korean temples. First feature is as guardian of the temple. Second feature is the dragon as the protector of the Buddha and the Dharma. The Buddhist dragon attained great success, and this proves that the Korean people has a profound sensitivity and great faith into this deity.

EVOLUTION OF DEVELOPMENT THEORY AND IT ,S RESTRICTS IN KOREA

Kim Han- tcho 한국학술연구원 1971 Korea Observer Vol.3 No.4

A study on analytic model of social and psychological factors affecting family planning

Kim, Han-Tcho 釜山大學校 1973 論文集 Vol.16 No.1

都市化의 三面性에 관한 論考

金漢超(Kim Han-Tcho) 부산대학교 법학연구소 1976 법학연구 Vol.19 No.2

Triboelectric nanogenerator based on rolling motion of beads for harvesting wind energy as active wind speed sensor

Kim, Daewon,Tcho, Il-Woong,Choi, Yang-Kyu Elsevier 2018 Nano energy Vol.52 No.-

<P><B>Abstract</B></P> <P>Green energy techniques, such as harvesting wind energy, is gaining great attention as they can provide environmental-friendly and renewable power sources in this era of energy crisis. Here, we report a triboelectric nanogenerator (TENG) which harvest mechanical energy driven by wind that works as a sustainable power source as well as a self-powered wind speed sensor. By adopting a novel method that employs the rolling motion of polymer beads, which serve as freestanding layers, under the wind speed of 20 m/s, the TENG delivered output voltage up to 17.8 V, output current of 5.3 µA, and a corresponding output power density of 1.36 mW/cm<SUP>2</SUP>. The correlation between electrical outputs, wind velocity, width of electrode is systematically investigated. Furthermore, the fabricated device is able to generate an electrical energy regardless of the direction of the wind, and it works well even for long term in the surrounding environment. Additionally, the device is small in size and comparatively flat in its structure, further enhancing potential of its application, such as self-powered wind speed sensor, as an effective portable power source that is readily available to be used in our daily life.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A triboelectric nanogenerator operated with rolling motion of the polymer beads driven by wind (WB-TENG), is demonstrated. </LI> <LI> Under the wind speed of 20 m/s, the WB-TENG delivered output power density of 1.36 mW/cm<SUP>2</SUP>. </LI> <LI> Multi-directional operation of the WB-TENG with superior mechanical endurance is demonstrated. </LI> <LI> The WB-TENG has great potential of its application for wind speed sensor due to its small size and flat structure. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Direct-laser-patterned friction layer for the output enhancement of a triboelectric nanogenerator

Kim, Daewon,Tcho, Il-Woong,Jin, Ik Kyeong,Park, Sang-Jae,Jeon, Seung-Bae,Kim, Weon-Guk,Cho, Han-Saem,Lee, Heung-Soon,Jeoung, Sae Chae,Choi, Yang-Kyu Elsevier 2017 Nano energy Vol.35 No.-

<P><B>Abstract</B></P> <P>Among the many types of wasted energy around us, mechanical energy has been considered to have a considerable amount of potential to be scavenged due to its abundance and ubiquity in our lives. To convert ambient mechanical energy into electrical energy efficiently, the triboelectric nanogenerator (TENG) has been intensively studied. Polydimethylsiloxane (PDMS), due to its superior mechanical and electrical properties, has commonly been selected as a friction layer in TENGs. Herein, it is newly discovered that the output power of a fabricated TENG is highly correlated with the Young's modulus of PDMS. An enhancement of the output power is achieved by the optimization of the PDMS mixture ratio. In addition, to improve the output power of the TENG further, a well-ordered microstructure was directly created on the surface of the PDMS by means of ultrafast laser irradiation. Direct patterning to create the surface morphology on the PDMS surface with the aid of laser irradiation is more efficient than conventional surface modification techniques such as replication and a few microfabrication steps. Compared to a control TENG using bare PDMS, an increase in the output power of more than twofold is achieved by an experimental TENG using patterned PDMS with a laser power of 29mW. The TENG utilizing the patterned PDMS achieves a maximum output power density level of 107.3μW/cm<SUP>2</SUP>.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Direct-laser-patterned polydimethylsiloxane (PDMS) is utilized as a triboelectric dielectric layer. </LI> <LI> Correlation between the Young's modulus of the PDMS and the corresponding electrical performance of the TENG is discovered. </LI> <LI> Optimal condition of laser power for maximum electrical output power is experimentally analyzed. </LI> <LI> By using femtosecond laser irradiation, micro/nanostructures are directly patterned on an appropriately prepared PDMS. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Self-powered fall detection system using pressure sensing triboelectric nanogenerators

Jeon, Seung-Bae,Nho, Young-Hoon,Park, Sang-Jae,Kim, Weon-Guk,Tcho, Il-Woong,Kim, Daewon,Kwon, Dong-Soo,Choi, Yang-Kyu Elsevier 2017 Nano energy Vol.41 No.-

<P><B>Abstract</B></P> <P>With the rapidly increasing number of older people in our societies, fall detection is becoming more important: Older adults may fall at home when they are alone and they may not be found in time for them to get help. In addition, a fall itself can cause serious injuries such as lacerations, fractures and hematomas. Although many previous studies have been reported on various fall detection technologies based on wearable sensors, the inconvenience of wearing them is problematic. Vision or ambient based methods may be alternatives, but high cost and complex installation process limit applicable areas. We propose a cost-effective, ambient-based fall detection system based on a pressure sensing triboelectric nanogenerator (TENG) array. Apart from simple observation of output signal waveforms according to different actions, key technologies, including appropriate filtering and distinguishing between falls and daily activities, are demonstrated with data acquisition from 48 daily activities and 48 falls by eight participants. The proposed system achieves a classification accuracy of 95.75% in identifying actual falls. Due to its low cost, easy installation and notable accuracy, the proposed system can be immediately applied to smart homes and smart hospitals to prevent additional injuries caused by falls.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A self-powered fall detection system was demonstrated using a TENG array. </LI> <LI> A statistical study over eight participants was carried out for general application. </LI> <LI> The maximum number of activated cells was used as a feature for classification. </LI> <LI> The proposed fall detection system had a high classification accuracy of 95.75%. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>