Effect of Muscle Soft Tissue on Biomechanics of Lumbar Spine under Whole Body Vibration

Rui-Chun Dong,Li-Xin Guo 한국정밀공학회 2017 International Journal of Precision Engineering and Vol.18 No.11

The object of this study was to simulate effect of muscle soft tissue on resonant frequencies and configuration (deformation and displacement) of lumbar spine in vivo under whole-body vibration (WBV). The three-dimensional (3D) finite element (FE) models of human body including skin, muscle soft tissue, viscera, ligaments, lumbar intervertebral disc (LID) and skeleton were created and validated. Modal analysis was performed by FE method. Results were that muscle soft tissue increased the resonant frequencies of lumbar spine. The first vertical resonant frequency (FVRF) changed greatly with the variation of Young’s modulus of muscle soft tissue in range of 0.01 MPa-0.15 MPa. Muscle soft tissue reduced the modal displacement of the lumbar spine. Especially the modal displacement in the anteroposterior direction was reduced by at least 40%. The risk injury area of lumbar was at low lumbar region under vertical WBV. The conclusions were that muscle soft tissue played a very important role in biomechanics of lumbar spine, and we could contract muscles of whole body for protection of lumbar spine under WBV with high vibration amplitude. The findings could be helpful in understanding the biomechanics of lumbar spine under WBV and offer potential references for spinal disease protection and orthopedics.

Marine (sea) Familiarity Index and Its Influence to National Image

Rui, Dong-Gen,Jung, Yong-Ki,Lee, Chun-Su East Asia Business Economics Association 2019 East asian journal of business management Vol.7 No.3

Purposes - This study discusses various aspects of familiarity with the sea and how familiarity with the sea is perceived. This study also summarizes the literature on the factors of previous researches that affect the formation or decision of national image. Research design and methodology - Sea familiarity index was derived from the results of recognition of free association with the sea, friendliness with the sea, association of the sea with life, interest to the sea, Korea's representative marine regions, and sea related emotionalism. The familiarity with the sea (ocean) perceived by foreign visitors or foreigners in the future will be helpful in deriving a comparative research. Results - This study has identified the marine tourism resources, marine ecology, and the cognitive and emotional situations consumers feel that should be developed practically. If a continuous time series research is conducted in the future through these, it will be a chance to provide a basis for consumers' dynamic awareness. Conclusions - Through this study, it is pointed out that the research utilizing the sea and ocean to form national image highly suggested an opportunity to add and utilize new variables academically. This study on the perspective of the formation of national image suggests a new approach to add and utilize new variables to future research using the sea and ocean.

Sliding Mode Robust Control of Hydraulic Drive Unit of Hydraulic Quadruped Robot

Rui Zhu,Qingjun Yang,Yudong Liu,Rizhi Dong,Chunli Jiang,Jiaxing Song 제어·로봇·시스템학회 2022 International Journal of Control, Automation, and Vol.20 No.4

This paper focuses on the position control of the quadruped robot hydraulic drive unit (HDU). The proposed control strategy has the advantages of excellent output tracking performance, strong robustness, no chattering and low computational complexity. HDU has the characteristics of nonlinearity and parameter uncertainty, coupled with unpredictable external interference, which makes it difficult to achieve precise position control. In this paper, we first establish the mathematical model of the HDU based on the actual parameters and obtain the state space of the system. Through the pole placement, the simplified system can easily achieve the expected control goal. Then, the state equation of the error system is constructed, and the nonlinearity, parameter uncertainty and external interference of the HDU are summarized as the matched and unmatched uncertainties of the system. The integral sliding mode control (ISMC) is used to derive the control law, and the response characteristics of the system when pole placement and state feedback H∞ control are used for the nominal control are compared. It can be concluded that the system with state feedback H∞ control for nominal control has stronger robustness and can resist the unmatched uncertainties. Finally, the control law of the simplified system is used as feedforward and combined with the ISMC of the error system, the output tracking control framework of the HDU is proposed. Simulations and experiments show that the proposed control method has excellent tracking performance and strong robustness.

An Improved Wavelet PWM Technique with Output Voltage Amplitude Control for Single-phase Inverters

Chun-Fang Zheng,Bo Zhang,Dong-Yuan Qiu,Xiao-Hui Zhang,Rui Li 전력전자학회 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.4

Unlike existing pulse-width modulation (PWM) techniques, such as sinusoidal PWM and random PWM, the wavelet PWM (WPWM) technique based on a Harr wavelet function can achieve a high fundamental component for the output voltage, low total harmonic distortion, and simple digital implementation. However, the original WPWM method lacks output voltage control. Thus, the practical application of the WPWM technique is limited. This study proposes an improved WPWM technique that can regulate output voltage amplitude with the addition of a parameter. The relationship between the additional parameter and the output voltage amplitude is analyzed in detail. Experimental results verify that the improved WPWM exhibits output voltage control in addition to all the merits of the WPWM technique.

An Improved Wavelet PWM Technique with Output Voltage Amplitude Control for Single-phase Inverters

Zheng, Chun-Fang,Zhang, Bo,Qiu, Dong-Yuan,Zhang, Xiao-Hui,Li, Rui The Korean Institute of Power Electronics 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.4

Unlike existing pulse-width modulation (PWM) techniques, such as sinusoidal PWM and random PWM, the wavelet PWM (WPWM) technique based on a Harr wavelet function can achieve a high fundamental component for the output voltage, low total harmonic distortion, and simple digital implementation. However, the original WPWM method lacks output voltage control. Thus, the practical application of the WPWM technique is limited. This study proposes an improved WPWM technique that can regulate output voltage amplitude with the addition of a parameter. The relationship between the additional parameter and the output voltage amplitude is analyzed in detail. Experimental results verify that the improved WPWM exhibits output voltage control in addition to all the merits of the WPWM technique.

In situ growth of CdS spherical nanoparticles/Ti3C2 MXene nanosheet heterojunction with enhanced photocatalytic hydrogen evolution

Kai Chun-Mei,Kong Cui,Zhang Feng-Jun,Li Dong-Cai,Wang Ying-Rui,오원춘 한국세라믹학회 2022 한국세라믹학회지 Vol.59 No.3

Solar photocatalytic hydrogen production is considered as a potential solution to alleviate the current global energy situation. In this work, a novle CdS spherical nanoparticles/Ti3C2 MXene nanosheet (CM) heterostructure photocatalyst was prepared by in situ growth method, which has the characteristics of high efficiency and stability. The results showed that the CM sam- ple has regular morphology and size. When compared with pure CdS, its specific surface area increased and the hydrogen evolution performance also greatly improved. Among them, the hydrogen evolution of CM-0.06 is 1295 μmol·g−1·h−1 (λ > 420 nm), which is 7 times that of spherical CdS, and it also showed stronger stability. Tight interface contact can promote the transfer and migration of photo-generated carriers, and the effective separation of electron hole pairs can enhance the absorption of visible light. In addition, Ti3C2 MXene acts as an electron trap can further accelerate the separation of pho- togenerated electrons and holes. The synergistic effect between semiconductor CdS and Ti3C2 MXene nanosheets, which provides a new idea for the design of more stable and efficient CdS-based photocatalysts.

다국적 기업의 중국 진출에 대한 사례 분석

예동근(Dong Gen Rui),이춘수(Chun Su Lee) 한국무역연구원 2015 무역연구 Vol.11 No.4

In China, with a high context culture, Guanxi has long history and tradition and acts as an ‘invisible hand’. Guanxi is evolving in various forms in accordance with changing times. Guanxi is composed of diverse elements and thus substantial time, money and network are need for foreign firms to grasp its meaning and to utilize it. In this study, how Guanzi acts as an entry barrier for foreign firms in real Chinese business world are explored by conducting interviews on executives and employees in multinational home appliances, shipping logistics company and vessel engine manufacturer to develop case studies on influence of Guanxi and associated problems, predicaments and irregularities faced, and failures experienced. By doing so, implications for Korean firms and research Implications for future studies were drawn. Research Implication 1: Due to western influence, Chinese Guanxi are increasingly becoming business-minded and instrumental Guanxi and does not exerts continual influence but only temporary and isolated influence that are guided by self-interest. Research Implication 2: As Chinese economy becomes advanced, Guanxi will become more transparent and thus quality and price competitiveness will become more important factor than Guanxi influence. Research Implication 3: Since Chinese Guanxi is reciprocal and cultural sentiment of face-saving and recognition, a compensation in return must be provided in order for Guanxi to continue.

Analysis of STS Fault Current with Minimization Method of STS Turn off Delay Time

Jong-Gyu Lee,Rui Sun,Jae-Hun Jung,Eui-Cheol Nho,In-Dong Kim,Heung-Geun Kim,Tae-Won Chun,Nam-Sup Choi 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5

This paper deals with the analysis of fault current occurred in a power system including STS, PCS, and load, which are the part of a microgrid. In case of utility side short circuit fault a huge current may flow through a STS, which results in a severe power quality problem in the microgrid. Therefore, minimization of the fault current and STS breaking time is essential to obtain high power quality. The basic concept of the minimization method is described and the STS fault current magnitude is analyzed with the considerations of power, current direction, etc. The results can be used for the design of a high power quality power system including STS and PCSs.

한류와 중국 현대차의 상호작용효과에 관한 소고

서영식(Young-Sik Seo),예동근(Dong-Gen Rui),이춘수(Chun-Su Lee) 한국무역학회 2011 貿易學會誌 Vol.36 No.3

중국통상과 투자관계 제고를 위한 효과적인 꽌시(關係)의 연구명제 탐색에 관한 기초연구

김순우(Soon-Woo Kim),예동근(Dong-Gen Rui),이춘수(Chun-Su Lee) 한국관세학회 2011 관세학회지 Vol.12 No.2

The focus of this study is exploration of research proposition on the effective use of Guanxi. First, in addition to the existing research that emphasizes the role of Guanxi, transaction cost perspectives and O.L.I(Ownership-advantage, Location-advantage, Internalization-advantage) paradigm were considered in connection to the expansion of Guanxi. Especially, new eclectic theory(O.L.I + G), a new model on how to enter the Chinese market, is provided in this study. In order to establish effective Guanxi in China, it is critical to have discussions on how firms can enhance performance with characteristics of Chinese market and the culture as well as the core proposition as the center. Foremost, in terms of managing the capabilities of Guanxi, Guanxi is the relationship of trust and accountability and is a significant variable on enhancing resource efficiency.