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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.
DNA-PK Promotes the Mitochondrial, Metabolic, and Physical Decline that Occurs During Aging
Park, Sung-Jun,Gavrilova, Oksana,Brown, Alexandra L.,Soto, Jamie E.,Bremner, Shannon,Kim, Jeonghan,Xu, Xihui,Yang, Shutong,Um, Jee-Hyun,Koch, Lauren G.,Britton, Steven L.,Lieber, Richard L.,Philp, And Elsevier 2017 Cell metabolism Vol.26 No.2
신정한(Jeonghan Shin),채석봉(Seokbong Chae),신이수(Yisu Shin),박정목(Jungmok Park),송진석(Ginseok Song),김주하(Jooha Kim) 한국가시화정보학회 2021 한국가시화정보학회지 Vol.19 No.3
In the present study, we investigate the flow characteristics of a paraglider canopy with leading-edge tubercles by performing force measurement and surface flow visualizations. The experiment is conducted at Re = 3.3×10<SUP>5</SUP> in a wind tunnel, where Re is the Reynolds number based on the mean chord length and the free-stream velocity. The canopy model with leading-edge tubercles has flow characteristics of a two-step stall, showing an earlier onset of the first stall than the canopy model without leading-edge tubercles. However, the main stall angle of the tubercled model is much larger than that of the canopy model without tubercles, resulting in a higher aerodynamic performance at high angles of attack. The delay in the main stall is ascribed to the suppression of separation bubble collapse around the wingtip at high angles of attack.
이정한(Jeonghan Lee),박한훈(Hanhoon Park) 한국통신학회 2022 한국통신학회 학술대회논문집 Vol.2022 No.2
본 논문은 딥페이크(deepfake) 영상 검출을 위해 영상을 패치로 나누고 패치별로 위조 여부를 판별한 후, 각 패치에 대한 판별 결과를 취합하는 방법을 제시하고, StyleGAN2로 생성된 영상에 대한 검출 성능을 실험을 통해 검증한다. 실험 결과, 패치 크기에 따라 검출 정확도는 달라졌으나, 전반적으로 패치 기반 방법은 검출 정확도를 크게 개선할 수 있으며, 신뢰도가 높은 패치를 선별하는 과정을 추가함으로써 검출 정확도를 보다 향상시킬 수 있음을 확인하였다.
김정한(Jeonghan Kim),박기영(Kiyeong Park) 한국자동차공학회 2011 한국자동차공학회 학술대회 및 전시회 Vol.2011 No.11
In this paper, we study about the rear side vehicle detection system using image processing algorithm. Camera for video acquisition, controller to handle and rear-side vehicle detection algorithm was developed. In addition, the system applied to the actual vehicle and verified against the possibility of application for vehicle. Test results of this system, recognition in the stop state have good characteristics more than 95% effective recognition at the maximum 60m distance, distance error was ± 5m and relative speed error was ± 5㎞/h. Also, recognition in the drive state have 91.5%, 90.1% at day time and 72.1% at night time. Daytime recognition rate was good, but night recognition rate was relatively poor. For improvement of system performance, need algorithms improvement to raise of recognition rate, first of all, need to research for night-time recognition rate improvement.
VDAC oligomers form mitochondrial pores to release mtDNA fragments and promote lupus-like disease
Kim, Jeonghan,Gupta, Rajeev,Blanco, Luz P.,Yang, Shutong,Shteinfer-Kuzmine, Anna,Wang, Kening,Zhu, Jun,Yoon, Hee Eun,Wang, Xinghao,Kerkhofs, Martijn,Kang, Hyeog,Brown, Alexandra L.,Park, Sung-Jun,Xu, American Association for the Advancement of Scienc 2019 Science Vol.366 No.6472
<P><B>VDACs are MOM's ruin</B></P><P>Mitochondrial DNA (mtDNA) is normally kept within the mitochondria. It can be released into the cytosol in response to stress and thus encounter cytosolic DNA sensors, triggering type I interferon responses. During apoptosis, mtDNA release is mediated by macropores in the mitochondrial outer membrane (MOM) created by oligomerization of the proteins BAX and BAK. Kim <I>et al.</I> found that during oxidative stress, mtDNA escapes instead through macropores formed by oligomerization of voltage-dependent anion channels (VDACs) (see the Perspective by Crow). In a mouse model of lupus, an inhibitor of VDAC oligomerization diminished mtDNA release and downstream signaling events. This treatment reduced lupus-like symptoms in the model, suggesting a potential therapeutic route for conditions mediated by mtDNA release.</P><P><I>Science</I>, this issue p. 1531; see also p. 1445</P><P>Mitochondrial stress releases mitochondrial DNA (mtDNA) into the cytosol, thereby triggering the type Ι interferon (IFN) response. Mitochondrial outer membrane permeabilization, which is required for mtDNA release, has been extensively studied in apoptotic cells, but little is known about its role in live cells. We found that oxidatively stressed mitochondria release short mtDNA fragments via pores formed by the voltage-dependent anion channel (VDAC) oligomers in the mitochondrial outer membrane. Furthermore, the positively charged residues in the N-terminal domain of VDAC1 interact with mtDNA, promoting VDAC1 oligomerization. The VDAC oligomerization inhibitor VBIT-4 decreases mtDNA release, IFN signaling, neutrophil extracellular traps, and disease severity in a mouse model of systemic lupus erythematosus. Thus, inhibiting VDAC oligomerization is a potential therapeutic approach for diseases associated with mtDNA release.</P>
고효율 GPS-RTK 보정데이터에 기반한 정밀위치 결정
김정한(Jeonghan Kim),강태익(Taeik Kang),기창돈(Changdon Kee),박병운(Byungwoon Park) 대한전자공학회 2007 대한전자공학회 학술대회 Vol.2007 No.7
GPS has many fields of applications due to diversities of positioning accuracy, from several tens of meters to several millimeters. Using GPS carrier phase measurements, we can determine our positions with centimeter-level positioning accuracy in real-time. For this purpose, we should generate CPC(Carrier phase correction) whose range error including latency error is on millimeter-level. In this paper, we proposed methods of generating GPS-RTK corrections robust to time delay and transmitting compact correction messages in order to achieve centimeter-level positioning accuracy in real-time. To reduce the latency error caused by time delay during the data transfer, we introduced correction scheduling technique Transmitting less accurate CPC due to higher latency error more frequently, we could make the performance of GPS-RTK using 500bps data-link equivalent to that of GPS-RTK using high-rate data-link. To utilize low-bandwidth data-link in GPS-RTK system, we proposed a new GPS-RTK protocol named SNUR-2000 whose basic frame structure is identical with RTCM SC-104 version 3 standard. This protocol is compact and compatible with the proposed asynchronous transmission technique. Using this protocol, we can ensure high accuracy of GPS-RTK using as low as 500bps data-link for dual frequency 1-㎐ GPS-RTK. We developed a GPS-RTK system which implements the proposed methods and OTF(On-the-fly) ambiguity resolution algorithm. Real-time experimental results demonstrate that the performance of our GPS-RTK system with 500bps data-link is equivalent to that of GPS-RTK system without latency.
박수진(Sujin Park),이정한(Jeonghan Lee),이순영(Soonyoung Lee),유완석(Wansuk Yoo) 한국자동차공학회 2003 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
The elastic deflection of helical gear teeth is analyzed to investigate the deformation overlap. The deformation overlap is suggested as the basis for the tooth profile modification. The elastic contact theory and Finite Element Method are used to compute the contact force and teeth deflection. The developed computer program will be of much help to the improved design of manual transmissions for passenger cars.
Analysis on Degradation of Ferroelectric Memory
Sangwoo Kim,Jeonghan Kim,Soi Jeong,Kiryun Kwon,Changhyeon Han,Eunchan Park,Jiyong Yim,Been Kwak,Jiwon You,Daewoong Kwon 한국차세대컴퓨팅학회 2022 한국차세대컴퓨팅학회 학술대회 Vol.2022 No.10
Subthreshold swing degradation of ferroelectric-gate field effect transistor (FeFET) memory are analyzed through DC and fast drain current (ID)-gate voltage (VG) measurements. From the fast ID-VGs before endurance cycling, it is revealed that acceptor-like traps with millisecond-order response time mainly exist in the gate oxide of FeFETs and the traps cause the different subthreshold swing (SS) between erase and program states.