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Ultimate Strength of branch-rotated T-joints in Cold-formed Square Hollow Sections - Chord flange failure mode - (지관이 회전된 냉간성형 각형강관 T형 접합부의 최대내력(I) - 주관 플랜지 파괴모드 -)

  • Bae, Kyu Woong;Park, Keum Sung;Kang, Chang Hoon;Moon, Tae Sup
    • Journal of Korean Society of Steel Construction
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    • v.14 no.5
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    • pp.657-664
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    • 2002
  • This paper described the ultimate strength and deformation limit of the new uniplanar T-joints in cold-formed square hollow sections. In the configuration of the new T-joint, only a branch member is orientated to a chord member at 45 degrees in the plane of the truss. This study focused on the branch-rotated T-joints that were governed by chord flange failure in previous studies. Test results of the T-joint in cold-formed square hollow sections revealed a deformation limit of 3%B for $16.7{\leq}2{\gamma}(=B/T){\leq}33.3$ and $0.27{\leq}{\beta}(=b1/B){\leq}0.6$. The existing strength formulae for traditional T-joint were determined and a new yield-line model for the branch-rotated T-joint proposed. Finally, the strength formula on the yield-line analysis was compared with test results and the application range of the proposed formula recommended.

Value of Bone Scintigraphy and Single Photon Emission Computed Tomography (SPECT) in Lumbar Facet Disease and Prediction of Short-term Outcome of Ultrasound Guided Medial Branch Block with Bone SPECT

  • Koh, Won-Uk;Kim, Sung-Hoon;Hwang, Bo-Young;Choi, Woo-Jong;Song, Jun-Gul;Suh, Jeong-Hun;Leem, Jeong-Gill;Shin, Jin-Woo
    • The Korean Journal of Pain
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    • v.24 no.2
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    • pp.81-86
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    • 2011
  • Background: Facet joint disease plays a major role in axial low-back pain. Few diagnostic tests and imaging methods for identifying this condition exist. Single photon emission computed tomography (SPECT) is reported that it has a high sensitivity and specificity in diagnosing facet disease. We prospectively evaluated the use of bone scintigraphy with SPECT for the identification of patients with low back pain who would benefit from medial branch block. Methods: SPECT was performed on 33 patients clinically suspected of facet joint disease. After SPECT, an ultrasound guided medial branch block was performed on all patients. On 28 SPECT-positive patients, medial branch block was performed based on the SPECT findings. On 5 negative patients, medial branch block was performed based on clinical findings. For one month, we evaluated the patients using the visual analogue scale (VAS) and Oswestry disability index. SigmaStat and paired t-tests were used to analyze patient data and compare results. Results: Of the 33 patients, the ones who showed more than 50% reduction in VAS score were assigned 'responders'. SPECT positive patients showed a better response to medial branch blocks than negative patients, but no changes in the Oswestry disability index were seen. Conclusions: SPECT is a sensitive tool for the identification of facet joint disease and predicting the response to medial branch block.

The Motion Analysis of the limited Wrist Joint During Dart-Throwing Motion by Using Infrared Camera (적외선카메라를 이용한 다트던지기 운동에서의 제한된 손목관절 움직임 분석)

  • Park, Chan-Soo;Park, Jong-Il;Kim, Kwang Gi;Jang, Ik-Gyu;Kim, Tae-Yun;Lee, Sang lim;Baek, Goo Hyun
    • Journal of Biomedical Engineering Research
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    • v.34 no.2
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    • pp.55-62
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    • 2013
  • Wrist joints consist of irregularly shaped carpal bones and other complicated structures. Thus, evaluating the motion of a wrist joint is a challenging task. In this study, we used an infrared camera to perform a kinematic analysis of a dart-throwing motion. We measured the difference between the movement of a normal wrist and constrained wrist (wrist with a wrist glove) in the dart-throwing motion with thirty six healthy participants. We measured the ulna flexion - radial extension motion using the attached passive marker and analyzed it using Polygon software and SPSS. The pitch and yaw motions with a glove was bigger than the ones without a glove by 20 and 15 degrees, respectively. On the other hand, the roll motion without a glove was bigger than the one with a glove by 7 degree. Wilcoxon signed rank test (p<0.05) confirmed that there are significant differences between the motion with and without a glove. It was found that the magnitude of the pitch and yaw motion with a constrained wrist joint toward radial extension in dart-throwing motion is smaller than the one with a normal wrist joint. However, a normal wrist joint showed a bigger movement in the roll direction.

Strengthening of bolted shear joints in industrialized ferrocement construction

  • Ismail, M.;Shariati, M.;Abdul Awal, A.S.M.;Chiong, C.E.;Chahnasir, E. Sadeghipour;Porbar, A.;Heydari, A.;Khorami, M.
    • Steel and Composite Structures
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    • v.28 no.6
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    • pp.681-690
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    • 2018
  • This paper highlights results of some experimental work that deals with strengthening of bolted shear joints in thin-walled ferrocement structure where steel wires, bent into U-shape are considered as simple inserts around the bolt hole. The parameters investigated include the number of layers of wire mesh, edge distance of bolt hole, size and location of the inserts. Test results have shown that for small edge distance, failure occurred either in cleavage or shearing mode, and the strength of the joint increased with an increase in the edge distance. This continued up to an upper limit set by either tension or bearing failure. The experimental study further revealed that for a given edge distance the strength of a joint can significantly be enhanced by using U-inserts. The equations developed for predicting joint strength in ferrocement composites can also be modified to include the effects of the inserts with a good level of accuracy.

A New More Reliable Indicator for Confirmation of the Medial Branch in Radiofrequency Neurotomy -Case report- (고주파열응고술을 이용한 척수신경 후내측지 신경절제술에서 후내측지를 확인하는 새로운 기준 -증례 보고-)

  • Shin, Keun-Man;Choi, Sang-Eun;Yun, Seon-Hye;Lim, So-Young;Jung, Bae-Hee;Lee, Kee-Heon;Hong, Soon-Yong;Choi, Young-Ryong
    • The Korean Journal of Pain
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    • v.13 no.2
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    • pp.242-246
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    • 2000
  • Radiofrequency medial branch neurotomy is an effective way of controlling pain in the posterior compartment of the spine such as the facet joint, and the interspinous ligament. However, it is difficult to determine the exact location of the medial branch. Up until now we have relied on sensory response provoked by 50 Hz stimulation. The responses elicited using this method are quite subjective and can originate from sources other than the medial branch such as the periosteum, the intermediate or lateral branch. We need a confirmed indicator to locate the medial branch reliably. We applied 2 Hz stimulation under 0.4 volts to locate the medial branch and elicited a motor response. Twitching of multifidus and muscles around the SI joint was observed. The observation of these muscles provides a much more reliable method for confirmation of the medial branch. We have treated 45 chronic nonspecific low back pain patients using radiofrequency medial branch neurotomy with this method of confirming the medial branch.

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Joint wireless and computational resource allocation for ultra-dense mobile-edge computing networks

  • Liu, Junyi;Huang, Hongbing;Zhong, Yijun;He, Jiale;Huang, Tiancong;Xiao, Qian;Jiang, Weiheng
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.14 no.7
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    • pp.3134-3155
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    • 2020
  • In this paper, we study the joint radio and computational resource allocation in the ultra-dense mobile-edge computing networks. In which, the scenario which including both computation offloading and communication service is discussed. That is, some mobile users ask for computation offloading, while the others ask for communication with the minimum communication rate requirements. We formulate the problem as a joint channel assignment, power control and computational resource allocation to minimize the offloading cost of computing offloading, with the precondition that the transmission rate of communication nodes are satisfied. Since the formulated problem is a mixed-integer nonlinear programming (MINLP), which is NP-hard. By leveraging the particular mathematical structure of the problem, i.e., the computational resource allocation variable is independent with other variables in the objective function and constraints, and then the original problem is decomposed into a computational resource allocation subproblem and a joint channel assignment and power allocation subproblem. Since the former is a convex programming, the KKT (Karush-Kuhn-Tucker) conditions can be used to find the closed optimal solution. For the latter, which is still NP-hard, is further decomposed into two subproblems, i.e., the power allocation and the channel assignment, to optimize alternatively. Finally, two heuristic algorithms are proposed, i.e., the Co-channel Equal Power allocation algorithm (CEP) and the Enhanced CEP (ECEP) algorithm to obtain the suboptimal solutions. Numerical results are presented at last to verify the performance of the proposed algorithms.

3D Gait Analysis of Limb Salvage Patients with Osteoarticular Knee Allograft Reconstruction (슬관절 동종골을 이용한 사지 구제수술 환자의 3차원 보행분석)

  • Jang, Ik-Gyu;Park, Hong-Seong;Nam, Kyoung-Won;Hong, Man-Bok;Kim, Soo-Hyun;Kim, Han-Soo;Kang, Hyun-Guy;Kim, Kwang-Gi
    • Journal of Biomedical Engineering Research
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    • v.31 no.1
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    • pp.74-80
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    • 2010
  • This paper presents the three dimensional gait analysis of the patients with osteoarticular knee allograft reconstruction. The gait analysis has been performed in some medical fields such as orthopedics and neurosurgery for the purpose of the rehabilitation of patients. However, to the author's knowledge, the analysis of gait for the patients with osteoarticular knee allograft reconstruction caused by tumor has not been reported. In this work, In this work, we confirmed the validity of this method by analyzing 50 samples per one gait cycle obtained from each of 3 patients and 3 normal persons. The motion capture was performed using six infrared cameras. The symmetry and stability of the gait patterns are investigated (patients' r=0.39, p<0.05, normal persons' r=0.65, p<0.05) respectively using the correlation coefficients and the standard deviations of the joint angles of the left and right legs. It also would be applied to the comparison analysis where artificial knee joint is transplanted.

Ultimate Strength of branch-rotated T-joints in Cold-formed Square Hollow Sections-Chord web failure mode- (지관이 회전된 냉간성형 각형강관 T형 접합부의 최대내력(II)-주관 웨브 파괴모드-)

  • Bae, Kyu Woong;Park, Keum Sung;Kang, Chang Hoon;Moon, Tae Sup
    • Journal of Korean Society of Steel Construction
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    • v.15 no.1
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    • pp.69-76
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    • 2003
  • This paper described the ultimate strength and deformation limit of new uniplanar T-joints in cold-formed square hollow sections. The new T-joint had the configuration that only a branch member was oriented at 45 degrees to a chord member in the plane of the truss. This study focused on the branch-rotated T-joints governed by chord web failure. Based on the test results of the T-joint in cold-formed square hollow sections, the deformation lirnit was found to be 3%B for $16.7{\leq}2(B/T){\leq}33.3$ and $0.63{\leq}(b_1/B)=0.7$. Existing strength formulas for traditional T-joint were investigated, and the new strength formula for the branch-rotated T-joint was proposed. This proposed formula was based on column buckling theory considering the rounded corners of cold-formed square hollow sections. Finally, the optimization condition of yield stress and $2{\gamma}$ was recommended to select the optimized chord section.

Depth-first branch-and-bound-based decoder with low complexity (검출 복잡도를 감소 시키는 Depth-first branch and bound 알고리즘 기반 디코더)

  • Lee, Eun-Ju;Kabir, S.M.Humayun;Yoon, Gi-Wan
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.13 no.12
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    • pp.2525-2532
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    • 2009
  • In this paper, a fast sphere decoder is proposed for the joint detection of phase-shift keying (PSK) signals in uncoded Vertical Bell Laboratories Layered Space Time (V-BLAST) systems. The proposed decoder, PSD, consists of preprocessing stage and search stage. The search stage of PSD relies on the depth-first branch-and-bound (BB) algorithm with "best-first" orders stored in lookup tables. Simulation results show that the PSD is able to provide the system with the maximum likelihood (ML) performance at low complexity.

Numerical simulation of shear mechanism of concrete specimens containing two coplanar flaws under biaxial loading

  • Sarfarazi, Vahab;Haeri, Hadi;Bagheri, Kourosh
    • Smart Structures and Systems
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    • v.22 no.4
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    • pp.459-468
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    • 2018
  • In this paper, the effect of non-persistent joints was determined on the behavior of concrete specimens subjected to biaxial loading through numerical modeling using particle flow code in two dimensions (PFC2D). Firstly, a numerical model was calibrated by uniaxial, Brazilian and triaxial experimental results to ensure the conformity of the simulated numerical model's response. Secondly, sixteen rectangular models with dimension of 100 mm by 100 mm were developed. Each model contains two non-persistent joints with lengths of 40 mm and 20 mm, respectively. The angularity of the larger joint changes from $30^{\circ}$ to $90^{\circ}$. In each configuration, the small joint angularity changes from $0^{\circ}$ to $90^{\circ}$ in $30^{\circ}$ increments. All of the models were under confining stress of 1 MPa. By using of the biaxial test configuration, the failure process was visually observed. Discrete element simulations demonstrated that macro shear fractures in models are because of microscopic tensile breakage of a large number of bonded discs. The failure pattern in Rock Bridge is mostly affected by joint overlapping whereas the biaxial strength is closely related to the failure pattern.