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Multidisciplinary methodology to predict the performance of modular actuator-based manipulator
Kim, Keonwoo,Kim, Jehyeok,Kim, Jihoon,Kim, Hwa Soo,Kim, Jongwon Elsevier 2018 Robotics and computer-integrated manufacturing Vol.52 No.-
<P><B>Abstract</B></P> <P>In this paper, we propose a multidisciplinary methodology to predict the performance of a modular actuator-based robotic manipulator considering the flexibilities of the linkage and the joint. Generally, fast dynamics of manipulator caused by structural flexibility often leads to the residual vibrations and deflections. However, it is quite difficult to predict these types of phenomena analytically since the dynamic characteristics of the manipulator considerably vary with its posture. To address this issue effectively, we propose to utilize the finite element method as well as the Lagrange formulation for more accurate modeling of the mechanical flexibility in manipulator structure. To verify the viability of proposed method, we perform the simulation using a 3 degree-of-freedom (DOF) planar manipulator constructed with three modular actuators. Through the simulation, the sensitivity analysis and principal component analysis (PCA) are carried out for the settling time and deflection with respect to the motion profile and end effector position. It is observed that the structural flexibility of the link and flexibility of modular actuator originated from the harmonic drive as well as the end effector position have a significant effect on the settling time and the deflection. The parameters in the S-curve motion profile are other key factors to the motion time and settling time, which should be selected to minimize the cycle time for task completion.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The practical methodology is proposed to estimate the performance of manipulator. </LI> <LI> The flexibilities of manipulator are modeled via FEM and Lagrange formulation. </LI> <LI> The nonlinear compliance of harmonic drive is identified to consider the joint flexibility. </LI> <LI> The proposed methodology can reduce the cost and the time required for robot design. </LI> </UL> </P>
Kim, Injung,Park, Jongkeun,Kim, Jeong-Ki,Kim, Bong-Kyu,Lee, Hwayoung,Choi, Keonwoo,Yoon, Jong-Bok,Yoon, Sungjoo Kim Springer-Verlag 2014 Genes & Genomics Vol.36 No.3
T-cadherin is frequently down regulated in various cancers, however, the underlying mechanisms responsible have yet to be elucidated. A genome wide association study of a cohort of Korean adults revealed that the T-cadherin rs3865188 single nucleotide polymorphism (SNP) was associated with serum Adiponectin levels and that its genotypic variants were correlated with risk for colorectal cancer (CRC). To test the function of rs12444338, a SNP tightly linked to the rs3865188 SNP, in T-cadherin transcriptional regulation in colorectal cancer, its effect on transcriptional activity and the capacity of binding activity attributable to allelic variation of the rs12444338 SNP was investigated. An electrophoretic-mobility-shift assay (EMSA) revealed a specific nucleoprotein complex unique to the T allele probe, which displayed lower promoter activity when compared to the G allele. Based on the results of the EMSA using mutant probes, the consensus sequence of the putative transcription factor binding site was determined. Additionally, candidates for putative binding factors to the T allele were also identified. Collectively, the study data suggested that the rs12444338 SNP was involved in transcriptional regulation of T-cadherin gene (CDH13) and that the differential binding of transcription factors at the rs12444338 SNP resulted in altered gene expression. These results elucidate, at least in part, the regulation of T-cadherin expression in CRC and provide further information regarding the effect of nucleotide variation in its promoter region.
Keonwoo Choi,Dae Yoon Kim,Hyun Jin Kim,Gyojun Hwang,Mi Kyung Kim,Hyun Gon Kim,Soya Paik 대한영상의학회 2022 대한영상의학회지 Vol.83 No.4
Meningiomas are the most common intracranial tumors. However, microcystic and angiomatous meningiomas are very rare subtypes that present unusual imaging findings. Hence, radiological diagnosis of these tumors can be challenging. We herein describe a case of mixed angiomatous and microcystic meningioma in an 81-year-old male. MRI revealed an extra-axial mass with high T2 signal intensity, measuring 1.5 cm in diameter, with multiple tiny intralesional cysts and entrapped peritumoral cyst formation. After tumor resection, a histopathological diagnosis of mixed angiomatous and microcystic meningioma was made.
GPU-Accelerated Password Cracking of PDF Files
( Keonwoo Kim ),( Sangsu Lee ),( Dowon Hong ),( Jae-cheol Ryou ) 한국인터넷정보학회 2011 KSII Transactions on Internet and Information Syst Vol.5 No.11
Digital document file such as Adobe Acrobat or MS-Office is encrypted by its own ciphering algorithm with a user password. When this password is not known to a user or a forensic inspector, it is necessary to recover the password to open the encrypted file. Password cracking by brute-force search is a perfect approach to discover the password but a time consuming process. This paper presents a new method of speeding up password recovery on Graphic Processing Unit (GPU) using a Compute Unified Device Architecture (CUDA). PDF files are chosen as a password cracking target, and the Abode Acrobat password recovery algorithm is examined. Experimental results show that the proposed method gives high performance at low cost, with a cluster of GPU nodes significantly speeding up the password recovery by exploiting a number of computing nodes. Password cracking performance is increased linearly in proportion to the number of computing nodes and GPUs.
Keonwoo Choi,Ji Young Choi,Hyuk Jung Kim,Hyun Jin Kim,Suk Ki Jang 대한영상의학회 2023 대한영상의학회지 Vol.84 No.3
Purpose This study aimed to determine the incremental value of using a structured report (SR) for US examinations of the pediatric appendix. Materials and Methods Between January 2009 and June 2016, 1150 pediatric patients with suspected appendicitis who underwent US examinations of the appendix were included retrospectively. In November 2012, we developed a five-point scale SR for appendix US examinations. The patients were divided into two groups according to the form of the US report: free-text or SR. The primary clinical outcomes were compared between the two groups, including the rate of CT imaging following US examinations, the negative appendectomy rate (NAR), and the appendiceal perforation rate (PR). Results In total, 550 patients were included in the free-text group and 600 patients in the SR group. The rate of additional CT examinations decreased by 5.3% in the SR group (8.2%, p = 0.003), and the NAR decreased by 8.4% in the SR group (7.8%, p = 0.028). There was no statistical difference in the appendiceal PR (37.6% vs. 48.0%, p = 0.078). Conclusion The use of an SR to evaluate US examinations for suspected pediatric appendicitis results in lower CT use and fewer negative appendectomies without an increase in appendiceal PR.
중복제거 파일 시스템을 적용한 분산 파일 시스템에서의 청크 배치 기법
김건우 ( Keonwoo Kim ),김지홍 ( Jeehong Kim ),엄영익 ( Young Ik Eom ) 한국정보처리학회 2013 한국정보처리학회 학술대회논문집 Vol.20 No.1
대량의 데이터를 효과적으로 저장하고 관리하기 위해서 클라우드 스토리지 시스템에서는 분산파일 시스템 기술이 이용되고 있다. 그러나 데이터가 증가함에 따라 분산 파일 시스템을 이용함에도 스토리지 확장 비용이 증가하게 된다. 본 논문에서는 분산 파일 시스템의 스토리지 확장 비용을 줄이기 위해서 우리는 중복제거 파일 시스템을 적용한 분산 파일 시스템에서의 청크 배치 기법을 제안한다. 오픈 소스 기반의 분산 파일 시스템인 MooseFS 에 중복제거 파일 시스템인 lessfs 를 적용함으로써 스토리지의 가용공간을 늘릴 수 있으며, 이는 스토리지 확장 비용을 줄이는 효과를 가져온다. 또한, 동일한 청크는 같은 청크 서버에 배치 시킴으로써 중복제거 기회를 높인다. 실험을 통해서 제안 시스템의 중복제거량과 성능에 대해서 평가한다.