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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.
( Hye Won Lee ),( Se Rim Oh ),( Dong Yun Kim ),( Yechan Jeong ),( Seungtaek Kim ),( Beom Kyung Kim ),( Seung Up Kim ),( Do Young Kim ),( Sang Hoon Ahn ),( Kwang-hyub Han ),( Jun Yong Park ) 대한간학회 2018 Gut and Liver Vol.12 No.3
Background/Aims: The treatment with daclatasvir plus asu-naprevir (DCV+ASV) is associated with potent antiviral effects in patients with genotype 1b hepatitis C virus (HCV) infec-tion. We investigated the real-world efficacy, changes in liver stiffness and noninvasive fibrosis markers, and the safety of DCV+ASV treatment in Korean patients. Methods: In to-tal, 363 patients with chronic hepatitis C were treated with DCV+ASV between August 2015 and January 2017. Finally, we analyzed the data of 270 patients who were monitored for at least 12 weeks after the end of treatment. Results: The mean age was 60.7 years, and females predominated (60.4%). Most patients (64.8%) were treatment-naïve, and 56 patients (20.7%) had cirrhosis. Two hundred fifty-seven (95.2%) and 251 (93.0%) patients achieved end-of-treatment responses and sustained virological responses at 12 weeks posttreatment (SVR12), respectively. The SVR12 rates were higher in patients who were <65 years of age, males, without cirrhosis and had lower HCV RNA levels. All LS values and fibrosis-4 and aspartate aminotransferase-to-platelet ratio in-dex values declined from baseline to the time of assessment of SVR12. Conclusions: The DCV+ASV therapy resulted in a high SVR12 and improved liver fibrosis; the treatment was well tolerated in patients with genotype 1b HCV infections. (Gut Liver 2018;12:324-330)
Diagnostic imaging features of normal anal sacs in dogs and cats
Yechan Jung,Eunseok Jeong,Sangjun Park,Jimo Jeong,Ul Soo Choi,Min Su Kim,Nam-Soo Kim,Kichang Lee 대한수의학회 2016 Journal of Veterinary Science Vol.17 No.3
This study was conducted to provide normal reference features for canine and feline anal sacs using ultrasound, low-field magnetic resonance imaging (MRI) and radiograph contrast as diagnostic imaging tools. A total of ten clinically normal beagle dogs and eight clinically normally cats were included. General radiography with contrast, ultrasonography and low-field MRI scans were performed. The visualization of anal sacs, which are located at distinct sites in dogs and cats, is possible with a contrast study on radiography. Most surfaces of the anal sacs tissue, occasionally appearing as a hyperechoic thin line, were surrounded by the hypoechoic external sphincter muscle on ultrasonography. The normal anal sac contents of dogs and cats had variable echogenicity. Signals of anal sac contents on low-field MRI varied in cats and dogs, and contrast medium using T1-weighted images enhanced the anal sac walls more obviously than that on ultrasonography. In conclusion, this study provides the normal features of anal sacs from dogs and cats on diagnostic imaging. Further studies including anal sac evaluation are expected to investigate disease conditions.
Kim, Yechan,Moon, Youngtaek,Kang, Dahye,Hong, Sungwoo The Royal Society of Chemistry 2014 Organic & Biomolecular Chemistry Vol.12 No.21
<P>An efficient and practical method for effecting a tandem C–H alkenylation/C–O cyclization has been achieved <I>via</I> the C–H functionalization of flavone derivatives. The synthetic utility of the one-pot sequence was demonstrated by obtaining convenient access to coumarin-annelated benzopyrans. The reaction scope for the transformation was found to be fairly broad, affording good yields of a wide range of flavone- or coumarin-fused benzopyran motifs, which are privileged structures in many biologically active compounds.</P> <P>Graphic Abstract</P><P>An efficient and practical method for effecting a tandem C–H alkenylation/C–O cyclization has been achieved <I>via</I> the C–H functionalization of flavone derivatives. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c4ob00180j'> </P>
Kim, Yechan,Kim, Seoung-Tae,Kang, Dahye,Sohn, Te-ik,Jang, Eunyoung,Baik, Mu-Hyun,Hong, Sungwoo Royal Society of Chemistry 2018 Chemical Science Vol.9 No.6
<▼1><P>A new, bidentate, chiral directing group derived from 2,2-dimethyl-1-(pyridin-2-yl)propan-1-amine was discovered, which enables stereoselective palladium(<SMALL>II</SMALL>)-catalyzed intramolecular C(sp<SUP>3</SUP>)–O bond formation.</P></▼1><▼2><P>The systematic investigation of chiral bidentate auxiliaries has resulted in the discovery of a chiral 2,2-dimethyl-1-(pyridin-2-yl)propan-1-amine-derived directing group that enables stereoselective palladium(<SMALL>II</SMALL>)-catalyzed intramolecular C(sp<SUP>3</SUP>)–O bond formation. This new chiral directing group exhibited high reactivity in the activation of methylene C(sp<SUP>3</SUP>)–H bonds with excellent levels of stereoselectivity (a diastereomeric ratio of up to 39 : 1), which allowed the construction of a wide range of oxaspirocycles. Mechanistic investigations were also conducted to elucidate the reaction mechanism and understand the origin of the diastereoselectivity. DFT calculations suggest that only modest levels of diastereoselectivity are accomplished at the rate-determining C–H metalation–deprotonation step and the d.r. is further enriched at the reductive elimination step.</P></▼2>
Thickness-dependent thermal conductivity of ultrathin (< 100 nm) barium titanate films
Kim, Yechan,Park, Joonsuk,Shin, Jeongwoo,An, Jihwan,Cho, Jungwan Elsevier 2019 CERAMICS INTERNATIONAL Vol.45 No.1
<P><B>Abstract</B></P> <P>Thin film barium titanate (BaTiO<SUB>3</SUB>) is a promising material in the electronics and ceramics industry owing to its compelling dielectric properties. A number of works have investigated its dielectric and structural properties, but less studied are its thermal properties particularly at sub-100 nm thicknesses. Here, we measure the room-temperature thermal conductivity of ultrathin (< 100 nm), pulsed laser deposited BaTiO<SUB>3</SUB> films. The measured thermal conductivities are thickness-dependent, and this trend is consistent with the thickness-dependent crystallinity of the films. Transmission electron microscopy analysis of the films reveals the presence of an initial amorphous layer ~ 60 nm thick from the growth interface and the subsequent formation of columnar grains of width ~ 12 nm that are embedded within an amorphous matrix. For a region that incorporates grains with columnar morphology, we find that cross-plane heat conduction may be favored by 30–40% over in-plane heat conduction due to the columnar morphology of grains.</P>