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Distal End Force Estimation of Tendon-sheath Mechanism Using a Spring Sheath
Jeonghan Kim,Kyungnam Kim,Yechan Seo,Junyoung Park,Byung Gon Kim,Sooyong Choi,Chanwoo Kim,Daehie Hong 한국정밀공학회 2023 International Journal of Precision Engineering and Vol.24 No.12
Tendon-sheath mechanism (TSM) is often used as a power transmission system in many applications, such as rehabilitation, wearables, and endoscopic surgery robots. It comprises a tendon for transmitting the power and a sheath to guide the tendon. The tendon passes through a narrow and harsh pathway to actuate an end-effector. Consequently, TSM exhibits highly nonlinear force transmission characteristics, resulting in poor control performance. Additionally, attaching and using a force feedback sensor at its distal end is virtually impossible in most applications owing to space constraints and safety concerns. To address these drawbacks, this study proposes a novel sensing spring wire to estimate the distal end force in TSM. Unlike existing methods, the proposed technique does not require complex hyperparameters or modeling and uses only a mechanical part to predict the force. The sensing wire is composed of the sheath. The biocompatibility, simple structure, and small size of the spring sheath facilitate convenient interaction with the existing TSM. Additionally, the spring sheath exhibits the characteristics of a spring, which ensures a linear relationship between the displacement and force. The results indicate that after calibrating the spring sensor, the distal end force can be easily determined using the proximal force despite the absence of an electrical sensor. In situations where the friction is different for each shape, when the force at the distal end was estimated using only the force at the proximal end measured by the sensor, the average RMSE was 75.91mN and the maximum error was 176.52mN. The proposed method verifies that the proximal tension and displacement data are sufficient to estimate the force.
Power Plant Pump Process Model Error Minimization Technique for Improving Simulator Fidelity
SooYong Yun,Kwan-Woong Gwak,Seung-Hyun Byun,Deockho Kim,Jaeyong Cho,Man-su Shin,ChangHyun Kim 제어로봇시스템학회 2021 제어로봇시스템학회 국제학술대회 논문집 Vol.2021 No.10
The power plant simulator is used to simulate the actual operation of a power plant, and for training and control verification. The simulator is built with the design data during the plant construction. The fidelity is low in the initial stage of operation because power plant modifications, deterioration, and logic corrections are not sufficiently reflected in a timely manner. To solve this problem, we propose a model error minimization technique for a pump process, one of the fundamental elements of the plant process, to improve fidelity. Model accuracy is improved by adjusting the parameters of the pump rated speed and characteristic curve based on the actual operating data. Performance is verified using actual operation data of the boiler feedwater pump in the circulating fluidized bed power plant.
Influence of Physical Load on the Stability of Organic Solar Cells with Polymer
Sooyong Lee,Hwajeong Kim,Youngkyoo Kim 한국태양광발전학회 2016 Current Photovoltaic Research Vol.4 No.2
We report the effect of physical load on the stability of organic solar cells under physical loads. The active layers in organic solar cells were fabricated with bulk heterojunction films (BHJ) films of poly (3-hexylthiophene) and phenyl-C61-butyric methyl ester. The loading time was varied up to 60 s by keeping the physical load constant. Results showed that the open circuit voltage was not nfluenced by the physical load but other solar cell parameters were sensitive to the loading time. The fill factor was very slightly increased at 15 s, while short circuit current density was well kept for 30 s. The power conversion efficiency was reasonably maintained for 45 s but became significantly decreased by the continuous loading for 60 s.
Sooyong Lee,Jooyeok Seo,Jaehoon Jeong,Chulyeon Lee,Myeonghun Song,Hwajeong Kim,Youngkyoo Kim 한국태양광발전학회 2017 Current Photovoltaic Research Vol.5 No.3
Here we report the influence of thermal treatment on the performance of high efficiency polymer solar cells with the bulk heterojunction films of poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b:4,5-b"] dithiophene-alt-3-fluorothieno[3,4-b]thiophene-2-carboxylate] (PTB7-Th) and [6,6]-phenyl C71 butyric acid methyl ester (PC71BM). The crystalline nanostructure of PTB7-Th:PC71BM layers, which were annealed at three different temperatures, was investigated by employing synchrotron radiation grazing incidence X-ray diffraction (GIXD) technique. Results showed that the device performance was slightly reduced by thermal annealing at 50°C but became significantly poor by thermal annealing at 100°C. The poor device performance by thermal annealing was attributed to the collapse in the crystalline nanostructure of PTB7-Th in the PTB7-Th:PC71BM layers as evidenced by the GIXD measurements that exhibited huge reduction in the intensity of PTB7-Th (100) peak even at 50°C.
Kim, Sooyong,Kang, Minhyeok International Academy of Physical Therapy Research 2021 Journal of International Academy of Physical Ther Vol.12 No.2
Background: Although the scapular posterior tilt movement could facilitate the lower trapezius (LT) muscle activity, no study identified the effects of the scapular posterior tilt movement on the selective activation of the LT muscle during prone shoulder extension. Objectives: To examine the influences of additional scapular posterior tilt on electromyography (EMG) of the upper trapezius (UT) and the LT muscles during prone shoulder extension. Design: Cross-sectional study. Methods: There were 15 asymptomatic male participants in this study who performed prone shoulder extension with and without scapular posterior tilt movements. For the scapular posterior tilt movements, participants performed visual biofeedback training for scapular movement using motion sensor. During the exercises, the EMG activity of the UT and LT was recorded using surface EMG system. Results: The EMG activity of the LT significantly increased during prone shoulder extension with scapular posterior tilt compared to that of general prone shoulder extension, whereas that of the UT was not significantly different between the two exercises. Moreover, scapular posterior tilt application significantly decreased UT/LT muscle activity ratio. Conclusion: Scapular posterior tilt movement may be emphasized during exercise when facilitating LT muscle activation.
Sooyong Lee,Hwajeong Kim,Youngkyoo Kim 한국태양광발전학회 2020 Current Photovoltaic Research Vol.8 No.4
Here we report the long-term stability of polymer:nonfullerene solar cells which were stored under dark and indoor light condition. The polymer:nonfullerene solar cells were fabricated using bulk heterojunction (BHJ) layers of poly[(2,6-(4,8-bis(5-(2-ethylhexyl) thiophen-2-yl)-benzo[1,2-b:4,5-b′]dithiophene))-alt-(5,5-(1′,3′-di-2-thienyl –5′,7-bis(2-ethylhexyl)benzo[1′,2′-c:4′,5′-c′]dithiophene-4,8-dione))] (PBDB-T) and 3,9-bis(6-methyl-2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d:2′,3-d′]-s-indaceno[1,2-b:5,6-b′]dithiophene (IT-M). To investigate their long-term stability, the PBDB-T:IT-M solar cells were stored in an argon-filled glove box. One set of the fabricated solar cells was completely covered with an aluminum foil to prevent any effect of light, whereas another set was exposed to indoor light. The solar cells were subjected to a regular performance measurement for 40 weeks. Results revealed that the PBDB-T:IT-M solar cells underwent a gradual decay in performance irrespective of the storage condition. However, the PBDB-T:IT-M solar cells stored under indoor light condition exhibited relatively lower power conversion efficiency (PCE) than those stored under the dark. The inferior stability of the solar cells under indoor light was explained by the noticeably changed optical absorption spectra and dark spot generation, indicative of degradations in the BHJ layers.
Transient Analysis of a Simple Cycle Gas Turbine Engine
Kim, SooYong,Soudarev, B. The Korean Society for Aeronautical and Space Scie 2000 International Journal of Aeronautical and Space Sc Vol. No.
A method to simulate the gas turbine transient behavior is developed. The basic principles of the method and main input data required are described. Calculation results are presented in terms of whole operating regime of the engine. The influence of initial parameters such as starting engine power, moment of inertia of the rotor, fuel schedule on performance characteristics of gas turbine during transient operation is shown. In addition, the effect of bleeding air on transient behavior is also considered. For validation of the developed computer code, a comparative analysis with experimental data obtained from a heavy duty gas turbine is made. Calculation results agree well with the experimental data for the range of operating regime studied and proved applicability of the developed technique to initial design stage of control system.