• Earthquakes and Structures
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• v.21 no.6
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• pp.613-625
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• 2021

Non-seismically designed eccentric reinforced concrete beam-column joints were extensively used in existing reinforced concrete frame buildings, which were found to be vulnerable to seismic action in many incidences. To provide a fundamental understanding of the seismic performance and failure mechanism of the joints, three 2/3-scale exterior beam-column joints with non-seismically designed details were cast and tested under reversed cyclic loads simulating earthquake excitation. In this investigation, particular emphasis was given on the effects of the eccentricity between the centerlines of the beam and the column. It is shown that the eccentricity had significant effects on the damage characteristics, shear strength, and displacement ductility of the specimens. In addition, shear deformation and the strain of joint hoops were found to concentrate on the eccentric face of the joint. The results demonstrated that the specimen with an eccentricity of 1/4 column width failed in a brittle manner with premature joint shear failure, while the other specimens with less or no eccentricity failed in a ductile manner with joint shear failure after beam flexural yielding. Test results are compared with those predicted by three seismic design codes and two non-seismic design codes. In general, the codes do not accurately predict the shear strength of the eccentric joints with non-seismic details.

• Journal of Information Processing Systems
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• v.17 no.5
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• pp.933-946
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• 2021

In the non-orthogonal multiple access (NOMA) system, multiple user signals on the single carrier are superimposed in a non-orthogonal manner, which results in the interference between non-orthogonal users and noise interference in the channel. To solve this problem, an improved algorithm combining regularized zero-forcing (RZF) precoding with minimum mean square error-serial interference cancellation (MMSE-SIC) detection is proposed. The algorithm uses RZF precoding combined with successive over-relaxation (SOR) method at the base station to preprocess the source signal, which can balance the effects of non-orthogonal inter-user interference and noise interference, and generate a precoded signal suitable for transmission in the channel. At the receiver, the MMSE-SIC detection algorithm is used to further eliminate the interference in the signal for the received superimposed signal, and reduce the calculation complexity through the QR decomposition of the matrix. The simulation results show that the proposed joint detection algorithm has good applicability to eliminate the interference of non-orthogonal users, and it has low complexity and fast convergence speed. Compared with other traditional method, the improved method has lower error rate under different signal-to-interference and noise ratio (SINR).

• Korean Journal of Applied Biomechanics
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• v.34 no.2
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• pp.93-103
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• 2024

Objective: The purpose of this study was to investigate whether dancers with chronic ankle instability (CAI) exhibit different characteristics in dynamic postural control ability and ankle joint laxity compared to dancers without CAI and non-dancers with CAI. Method: Twelve dancers with CAI, 14 dancers without CAI, and 12 non-dancers with CAI participated in the study. Dynamic balance was evaluated using the Star Excursion Balance Test (SEBT) and the single-leg hop balance. The laxity of the ankle joint was evaluated through the anterior drawer test and the talar tilt test. SEBT measured maximum reach distances in anterior, posteromedial, and posterolateral directions. Single-leg hop assessed center of pressure (COP) and time-to-boundary (TTB) outcomes. One-way ANOVA and Chi-square tests were performed to compare the outcome variables among the three groups. Results: Dancers with CAI demonstrated greater reach distance in the posterolateral direction compared to non-dancers with CAI during SEBT (p=.014). Secondly, dancers without CAI showed greater reach distance in the posterolateral (p<.001) and posteromedial (p=.001) directions during SEBT compared to non-dancers with CAI. Additionally, dancers without CAI exhibited better postural control with higher TTB AP mean of minima (p=.003) and TTB AP standard deviation of minima (p=.012) during single-leg hop compared to nondancers with CAI. Thirdly, dancers with CAI showed a lower positive rate during the anterior drawer test compared to non-dancers with CAI (p=.019). Conclusion: Dancers with CAI demonstrated better ankle function and reduced mechanical instability compared to non-dancers with CAI. Therefore, to elucidate the underlying mechanisms of lateral ankle sprain and CAI development exacerbation in dancers, additional factors that can affect ankle sprain, such as visual dependence during postural control and evaluation in dance movements, should be explored.

• International journal of advanced smart convergence
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• v.7 no.1
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• pp.15-23
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• 2018

Spectrum allocation is a key operation in cognitive radio networks (CRNs), where secondary users (SUs) are usually selfish - to achieve itself utility maximization. In view of this context, much prior lit literature proposed spectrum allocation base on non-cooperative game models. However, the most of them proposed non-cooperative game models based on complete information of CRNs. In practical, primary users (PUs) in a dynamic wireless environment with noise uncertainty, shadowing, and fading is difficult to attain a complete information about them. In this paper, we propose a non-cooperative game joint hidden markov model scheme for spectrum allocation in CRNs. Firstly, we propose a new hidden markov model for SUs to predict the sensing results of competitors. Then, we introduce the proposed hidden markov model into the non-cooperative game. That is, it predicts the sensing results of competitors before the non-cooperative game. The simulation results show that the proposed scheme improves the energy efficiency of networks and utilization of SUs.

• International Journal of Reliability and Applications
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• v.12 no.2
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• pp.103-116
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• 2011

A series-parallel system with independent but non-identical components is considered. The expressions have been derived for the joint reliability importance (JRI) of m (${\geq}2$) components, chosen from a series-parallel system. JRIs of components of two different series-parallel systems are studied analytically and graphically.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.932-935
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• 2005

Three dimensional laser welding technology for light car body is studied. A robot, a seam tracking system and 4kW CW Nd:YAG laser are used for three dimensional robot laser welding system. The Laser system is used 4kW Nd:YAG laser(HL4006D) of Trumpf and the Robot system is used IRB6400R of ABB. The Seam tracking system is SMRT-20LS of ServoRobot. The welding joint of steel plate are butt and lap joint. The 3-D welding for Non-linear Tailored blank is performed after the observation experiments of bead on plate. Finally, the welding process for non-linear tailored blank and front side member is developed.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.5
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• pp.809-818
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• 1997

An efficient non-recursive formulation of dynamic force analysis has been developed for serially connected multibody systems. Although derivation of equations of motion is based on a recursive dynamic formulation with joint relative coordinates, in the proposed formulation, dynamic forces such as joint reaction forces and driving force are computed non-recursively for specified joints. The efficiency of the proposed formulation has been proved by the operational count and the CPU time measure, comparing with that of the conventional recursive Newton-Euler formulation. A simulation of 7-DOF RRC robot arm has been carried out to validate solutions of reaction forces by comparing with those from a commercial dynamic analysis program DADS.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.441-448
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• 2009

In this study, the joint part of non-welding composite pile is investigated by a three dimensional finite element analysis. Special attention is given to the overall stress distribution under lateral, axial and tensional load conditions. Through comparisons with allowable stress of materials, a simple method is proposed to estimate the ultimate load condition of joint part. The appropriate design method is suggested and highlighted through the numerical analysis.

• Journal of Korean Tunnelling and Underground Space Association
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• v.25 no.4
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• pp.305-330
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• 2023

Unlike NATM tunnels, Shield TBM tunnels have split linings. Therefore, the stress distribution of the lining is different even if the lining is under the same load. Representative methods for analyzing the stress generated in lining in Shield TBM tunnels include Non-joint Mode that does not consider connections and a 2-ring beam-spring model that considers ring-to-ring joints and segment connections. This study is an analysis method by Break-joint Mode. However, we do not consider the structural role of segment lining connections. The effectiveness of the modeling is verified by analyzing behavioral characteristics against vibration loads by modeling with segment connection interfaces to which vertical stiffness and shear stiffness, which are friction components, are applied. Unlike the Non-joint mode, where the greatest stress occurs on the crown for static loads such as earth pressure, the stress distribution caused by contact between segment lining and friction stiffness produced the smallest stress in the crown key segment where segment connections were concentrated. The stress distribution was clearly distinguished based on segment connections. The results of static analysis by earth pressure, etc., produced up to seven times the stress generated in Non-joint mode compared to the stress generated by Break-joint Mode. This result is consistent with the stress distribution pattern of the 2-ring beam-spring model. However, as for the stress value for the train vibration load, the stress of Break-joint Mode was greater than that of Non-joint mode. This is a different result from the static mechanics concept that a segment ring consisting of a combination of short members is integrated in the circumferential direction, resulting in a smaller stress than Non-joint mode with a relatively longer member length.

• Physical Therapy Korea
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• v.23 no.3
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• pp.29-39
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• 2016

Background: In the treatment of temporomandibular joint (TMJ) disorder, the goals of traditional physical therapy are not only to reduce the inflammatory process leading to pain, but also to decrease joint overload and muscle hyperactivity. To achieve those goals, physical therapists generally use a photo-therapy, joint mobilization, and massage. Objects: To examine the impact of an unloading technique using non-elastic taping on the pain, opening mouth, functional level, and quality of life in patients with TMJ disorder. Method: Twenty patients with TMJ disorder were included in this study and randomly divided into the experimental ($n_1$=10), and control ($n_2$=10) groups. Traditional physical therapy including massage and stretching for 30 min was performed in both groups. Non-elastic taping was performed in the experimental group after traditional physical therapy, and they were recommended to keep the tape attached for 12 hours. Outcomes for pain, functional level, and quality of life were measured using a survey. The opening mouth was measured using a general ruler. Result: Significant differences were observed in the pain level, opening mouth, functional level, and quality of life after the intervention and on follow-up in both groups. However, we found that while the levels of all parameters were maintained throughout the follow-up period in the experimental group, the functional status level was not maintained throughout the follow-up period in the control group. Conclusion: Our unloading technique using non-elastic tape results comparable to those achieved by traditional physical therapy in the treatment of TMJ. However, the unloading taping method using non-elastic tape is more effective than traditional physical therapy in maintaining the impact of intervention.