Compact Modular Cycloidal Motor With Embedded Shape Memory Alloy Wires

Hwang, Donghyun,Ihn, Yong Seok,Kim, Keehoon Institute of Electrical and Electronics Engineers 2018 IEEE transactions on industrial electronics Vol.65 No.5

<P>In this study, we develop a rotary motor using embedded shape memory alloy (SMA) wires, with the aim of realizing a novel compact and modular motor that can generate high-torque bidirectional continuous rotation. Thus, we focus on designing the motion transmission mechanism and torque amplifier of the motor. The designed motion transmission mechanism that functions to convert the contraction/expansion of the SMA wires to rotational motion enables the motor to generate continuous rotation with relatively short-length SMA wires. Additionally, a double-disc cycloidal speed reducer designed as the torque amplifier allows the motor to reliably generate high torque with a compact structure due to its simple configuration, size variability, and torque amplification functionality. One of the advantages of the motor is that an actuating module could be additionally incorporated into the motor to achieve higher torque. In this case, the overall size and weight of the motor are marginally increased although the output torque capacity almost doubles. Hence, the energy density of the motor significantly increases. The study describes the main concept, operating principle, design, and experimental results of the output torque capacity, positioning characteristics, and frequency response of the proposed motor.</P>

GROWTH TEMPERATURE EFFECT ON THE PROPERTIES OF SnS ABSORBING LAYERS FOR THIN FILM SOLAR CELLS

Donghyun HWANG,Joo Hyung PARK,Chang Sik SON 한국신재생에너지학회 2017 AFORE Vol.2017 No.11

Design of Alignment Mark Stamper Module for LED Post-Processing

Donghyun Hwang,Young W. Sohn,Tae-ho Seol,YongHo Jeon,Moon G. Lee 한국생산제조학회 2015 한국생산제조학회지 Vol.24 No.2

Light emitting devices (LEDs) are widely used in the liquid crystal display (LCD) industry, especially for LCD back light units. Therefore, much research has been performed to minimize manufacturing costs. However, the current process does not process LED chips from broken substrates even though the substrate is expensive sapphire wafer. This is because the broken substrates lose their alignment marks. After pre-processing, LED dies are glued onto blue tape to continue post-processing. If auxiliary alignment marks are stamped on the blue tape, post-processing can be performed using some of the LED dies from broken substrates. In this paper, a novel stamper module that can stamp the alignment mark on the blue tape is proposed, designed, and fabricated. In testing, the stamper was reliable even after a few hundred stamps. The module can position the stamp and apply the pattern effectively. By using this module, the LED industry can reduce manufacturing costs.

On the design of a miniature haptic ring for cutaneous force feedback using shape memory alloy actuators

Hwang, Donghyun,Lee, Jaemin,Kim, Keehoon Institute of Physics Publishing 2017 Smart materials & structures Vol.26 No.10

<P>This paper proposes a miniature haptic ring that can display touch/pressure and shearing force to the user’s fingerpad. For practical use and wider application of the device, it is developed with the aim of achieving high wearability and mobility/portability as well as cutaneous force feedback functionality. A main body of the device is designed as a ring-shaped lightweight structure with a simple driving mechanism, and thin shape memory alloy (SMA) wires having high energy density are applied as actuating elements. Also, based on a band-type wireless control unit including a wireless data communication module, the whole device could be realized as a wearable mobile haptic device system. These features enable the device to take diverse advantages on functional performances and to provide users with significant usability. In this work, the proposed miniature haptic ring is systematically designed, and its working performances are experimentally evaluated with a fabricated functional prototype. The experimental results obviously demonstrate that the proposed device exhibits higher force-to-weight ratio than conventional finger-wearable haptic devices for cutaneous force feedback. Also, it is investigated that operational performances of the device are strongly influenced by electro-thermomechanical behaviors of the SMA actuator. In addition to the experiments for performance evaluation, we conduct a preliminary user test to assess practical feasibility and usability based on user’s qualitative feedback.</P>

Design of Alignment Mark Stamper Module for LED Post-Processing

Hwang, Donghyun,Sohn, Young W.,Seol, Tae-ho,Jeon, YongHo,Lee, Moon G. The Korean Society of Manufacturing Technology Eng 2015 한국생산제조학회지 Vol.24 No.2

Light emitting devices (LEDs) are widely used in the liquid crystal display (LCD) industry, especially for LCD back light units. Therefore, much research has been performed to minimize manufacturing costs. However, the current process does not process LED chips from broken substrates even though the substrate is expensive sapphire wafer. This is because the broken substrates lose their alignment marks. After pre-processing, LED dies are glued onto blue tape to continue post-processing. If auxiliary alignment marks are stamped on the blue tape, post-processing can be performed using some of the LED dies from broken substrates. In this paper, a novel stamper module that can stamp the alignment mark on the blue tape is proposed, designed, and fabricated. In testing, the stamper was reliable even after a few hundred stamps. The module can position the stamp and apply the pattern effectively. By using this module, the LED industry can reduce manufacturing costs.

Three-dimensional alteration of constricted alveolar ridge affected by root thrusting with and without open-flap decortication

Hwang, Donghyun,Lee, Won-June,Kim, Kyung-A,Baek, Seung-Hak,Park, Young-Guk,Kim, Su-Jung The Angle Orthodontist 2017 The Angle orthodontist Vol.87 No.5

<B>ABSTRACT</B><B>Objective:</B><P>To investigate the morphometric and histological alterations of the constricted alveolar ridge when affected by root thrusting with and without open-flap decortication.</P><B>Materials and Methods:</B><P>Eight beagles were divided into three groups: C, control without root thrusting; R, root thrusting only; RD, root thrusting with alveolar decortication. The ridge constriction model was prepared in 16 mandibular quadrants after extraction of the third premolars. Reciprocal root thrusting of the second and fourth premolars was performed toward the constricted ridge for 10 weeks, having a moment of 900 g-mm. Open-flap decortication was conducted on the constricted bone surface in group RD. Micro-CT-based histomorphometric analysis and trichrome-staining-based tissue fractional analysis were performed to evaluate morphometric and microstructural changes on the ridge.</P><B>Results:</B><P>Group R revealed a higher percentage of bone volume (P &lt; .001), lower bone mineral density (P &lt; .01), and higher trabecular number (P &lt; .001) than did group C, which was supported by a higher bone fraction woven to lamellar bone (P &lt; .05) resulting from histologic fractional analysis. However, group RD showed no significant difference from group C.</P><B>Conclusions:</B><P>Root thrusting toward the constricted ridge induced hypertrophic bone modeling with a high trabecular fraction on the ridge. However, combined open-flap decortication with root thrusting did not improve the volume or quality of the constricted ridge.</P>

Robust Design and Performance Verification of an In-Plane XYθ Micropositioning Stage

Donghyun Hwang,Jungwoong Byun,Jaehwa Jeong,Lee, M. G. IEEE 2011 IEEE TRANSACTIONS ON NANOTECHNOLOGY Vol.10 No.6

<P>This paper describes the robust design, fabrication, and performances verification of a novel ultraprecision XYθ micropositioning stage with piezoelectric actuator and flexure mechanism. The main goal of the proposed novel design is to combine a translational motion part and rotational motion part as a decoupled serial kinematics on a same plane. Proposed compound cymbal mechanisms of the translational motion part have functions of motion amplifier as well as motion guide. And Scott-Russell linkage mechanism is applied to the rotational motion part. In this research, Taguchi Design of Experiments is used for robust design with flexure notch hinge fabrication errors as noise factors. Target specifications of the design are sufficient range and bandwidth of motion. The proposed XYθ stage has a translational motion range of 58.0 μm and rotational motion range of 1.05 mrad, and a closed-loop resolution of ±2.5 nm, ±2.5 nm, and ±0.25 μrad in X-, Y-, and θ-directional motion, respectively. The proposed XYθ micropositioning stage has a novelty with in-plane and decoupled kinematic design, compared with many previously developed stages based on planar parallel kinematics.</P>

Substrate Temperature Effects on the Properties of Radio Frequency-Sputtered SnS Thin Films

Hwang, Donghyun,Shin, Jin-Yong,Lee, Sunmook,Park, Joo Hyung,Son, Chang-Sik American Scientific Publishers 2018 Nanoscience and nanotechnology letters Vol.10 No.5

PZT 기반 굽힘 힌지 스테이지의 최적화 설계에 관한 연구

황동현(Donghyun Hwang),박준호(Jun-Ho Park),정재화(Jaewha Jeong),이문구(Moon G. Lee) 한국정밀공학회 2008 한국정밀공학회 학술발표대회 논문집 Vol.2008 No.6월

덤프 연소기에서 음향가진을 이용한 연소불안정 제어

황동현(Donghyun Hwang),송윤호(Yoonho Song),안규복(Kyubok Ahn) 한국추진공학회 2016 한국추진공학회 학술대회논문집 Vol.2016 No.12

연소불안정의 open-loop control 연구가 다양한 탄화수소 계열의 연료를 이용하여 덤프 연소기에서 실험적으로 수행되었다. 동일한 실험조건 하에서 수행된 연소불안정 특성은 연료마다 다른 값을 갖는다. 하지만 각 연료에서 당량비 조정을 통해 비슷한 특성화학시간을 설정하게 되면, 불안정주파수와 최대 power spectral density는 거의 유사한 값을 갖게 된다. 이와 같은 조건에서 다양한 주파수와 진폭을 갖는 음향가진을 이용하여, 연소불안정 제어효과를 조사하였다. 실험결과는 입구속도, 가진 주파수 및 진폭이 제어효과에 영향을 미치며, 유사한 특성화학시간을 갖는 조건 하에선 연료에 관계없이 비슷한 수준의 불안정성 억압을 보여주었다. A study on the open-loop control of a combustion instability using different hydrocarbon fuels has been experimentally investigated. Each fuel had different combustion instability characteristics under same experimental conditions. By adjusting the equivalence ratio for similar characteristic chemical time, however, instability frequencies and maximum power spectral densities had nearly same values. Control effectiveness of a combustion instability using different frequencies and amplitude of acoustic excitation was investigated. The result showed that the inlet velocity, forcing frequency and amplitude affected the control effectiveness. The similar level of suppression was achieved regardless of the fuels in the case of the characteristic chemical time was similar.