• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.29 no.2
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• pp.407-410
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• 1999

Purpose; To find out the best imaging parameters for the diagnosis of disc in MRI imaging. Materials and methods; The diagnostic quality of the disc among the Tl, PD and T2 images of same patients02 joints, 223 images) was compared by visual(I-IV grades) and gray level measurement (pre- and infra-discal area) method. Results; PD images showed best results with 43.7％ of the images belonging to grade III (good) and with statistically significant higher difference of the gray levels at pre- and infra-discal areas. But there were no grade N (excellent) images. Conclusions; PD images are best method among Tl. PD and T2 images in diagnosing the disc but since there were no excellent images further imaging parameters should be studied for better images.

• Steel and Composite Structures
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• v.27 no.1
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• pp.49-74
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• 2018

Generally, beam-column joints are taken into account as rigid in assessment of seismic performance of reinforced concrete (RC) structures. Experimental and numerical studies have proved that ignoring nonlinearities in the joint core might crucially affect seismic performance of RC structures. On the other hand, to improve seismic behaviour of such structures, several strengthening techniques of beam-column joints have been studied and adopted in practical applications. Among these strengthening techniques, the application of FRP materials has extensively increased, especially in case of exterior RC beam-column joints. In current paper, to simulate the inelastic response in the core of RC beam-column joints strengthened by FRP sheets, a practical joint model has been proposed so that the effect of FRP sheets on characteristics of an RC joint were considered in principal tensile stress-joint rotation relations. To determine these relations, a combination of experimental results and a mechanically-based model has been developed. To verify the proposed model, it was applied to experimental specimens available in the literature. Results revealed that the model could predict inelastic response of as-built and FRP strengthened joints with reasonable precision. The simple analytic procedure and the use of experimentally computed parameters would make the model sufficiently suitable for practical applications.

• Proceedings of the KWS Conference
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• 2006.10a
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• pp.216-218
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• 2006

The application of aluminium alloy is increasing for lightweight and high quality transport vehicle. In this study, therefore, it is intended to apply the high speed hybrid welding method for marine grade aluminium alloy(A5083) used for shipbuilding that consists of 3 kW CW Nd:YAG laser and MIG welding process. For this purpose, the characteristics of process parameters(laser & arc combine angle and focal position of hybrid head to specimen) are investigated for hybrid fillet joint. This study also describes determination of heat distribution using finite element model of the T-joint fillet weld using the in-house solver which has been validated for different type of welding problems.

• Communications for Statistical Applications and Methods
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• v.7 no.3
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• pp.829-836
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• 2000

We shall derive Bayes estimators for he smaller and larger of two Pareto scale parameters with a common known shape parameter when the order of the scales is unknown and sample sizes are equal under squared error loss function. Also, we shall obtain biases and man squared errors for proposed Bayes estimators, and compare numerically performances for the proposed Bayes estimators.

• Journal of Korean Physical Therapy Science
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• v.9 no.1
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• pp.129-134
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• 2002

The aim of this study is to present the basic reference data of age and specipic gait parameters for Hemiplegia Patients. The basic gait parameters were extracted from 10 Adult Hemiplegia Patients, 5 left Hemiplegia Patients and 5 right Hemiplegia Patients, 50 to 60 years of age using VICON 512 Motion Analyzer. The results were as follows; 1) The mean Cadence of the left to the right hemiplegia were $75.81{\pm}28.10\;steps/min$, to $68.47{\pm}9.93\;steps/min$. 2) The mean Walking Speed of the left to the right hemiplegia were $0.45{\pm}0.28\;m/s$, to $0.44{\pm}0.14\;m/s$. 3) The mean Stride Length of the left to the right hemiplegia were $0.66{\pm}0.31\;m$, to $0.76{\pm}0.17m$. 4) The mean. maximal angles of joint on the pelvic tilt for different right or left hemiplegia were $8.59{\pm}5.13^{\circ}$, to $11.85{\pm}5.23^{\circ}$.(p>0.05) 5) The mean maximal angles of joint on the hip flexion motion for different right or left hemiplegia were $23.98{\pm}8.45^{\circ}$, to $25.81{\pm}5.39^{\circ}$.(p>0.05) 6) The mean maximal angles of joint on the knee flexion motion for different right or left hemiplegia were $29.52{\pm}10.24^{\circ}$, to $28.38{\pm}14.48^{\circ}$.(p>0.05) 7) The mean maximal angles of joint on the ankle dorsiflexion motion for different right or left hemiplegia were $14.68{\pm}5.03^{\circ}$, to $9.90{\pm}7.26^{\circ}$.(p>0.05) 8) The mean maximal angles of joint on the ankle plantarflexion motion for different right or left hemiplegia were $2.10{\pm}5.17^{\circ}$, to $8.63{\pm}5.81^{\circ}$.(p>0.05)

• Advances in Computational Design
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• v.1 no.1
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• pp.61-77
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• 2016

Seismic performance of structures depends on the force flow mechanism inside the structure. Discontinuity regions, like beam-column joints, are often affected during earthquake event due to the complex and discontinuous load paths. The evaluation of shear strength and identification of failure mode of the joint region are helpful to (i) define the strength hierarchy of the beam-column sub-assemblage, (ii) quantify the influence of different parameters on the behaviour of beam-column joint and, (iii) develop suitable and adequate strengthening scheme for the joints, if required, to obtain the desired strength hierarchy. In view of this, it is very important to estimate the joint shear strength and identify the failure modes of the joint region as it is the most critical part in any beam-column sub-assemblage. One of the most effective models is softened strut and tie model which was developed by incorporating force equilibrium, strain compatibility and constitutive laws of cracked reinforced concrete. In this study, softened strut and tie model, which incorporates force equilibrium equations, compatibility conditions and material constitutive relation of the cracked concrete, are used to simulate the shear strength behaviour and to identify failure mechanisms of the beam-column joints. The observations of the present study will be helpful to arrive at the design strategy of the joints to ensure the desired failure mechanism and strength hierarchy to achieve sustainability of structural systems under seismic loading.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.2
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• pp.505-513
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• 2014

This paper investigated the effect of joint on the earth pressure against an excavation wall in rockmass with the consideration of various rock and joint conditions. For this purpose, this study briefly reviewed of the previous earth pressure studies, and then numerical parametric studies were conducted based on the Discrete Element Method (DEM) to overcome the limitations of the previous studies. The numerical tests were carried out with the controlled parameters including rock types and joint conditions (joint shear strength, joint inclination angle, and joint set), and the magnitude and distribution characteristics of the induced earth pressure were investigated considering the interactions between the ground and the excavation wall. In addition, the earth pressures induced in rock stratum were compared with Peck's earth pressure for soil ground. The results showed that the earth pressure against an excavation wall in jointed rockmass were highly affected by different rock and joint conditions and thus different from Peck's empirical earth pressure for soil ground.

• International Journal of Aeronautical and Space Sciences
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• v.18 no.1
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• pp.56-62
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• 2017

Because adhesively bonded joints are used in many structural systems, it is important to predict accurate adhesive strengths. Composite aircraft with many joints are easily exposed to low temperatures and high relative humidity. This paper presents a humidity aging effect on the adhesive strength of a composite single-lap joint (SLJ). The adhesive strength of the SLJ is predicted using a finite element analysis with a cohesive zone model (CZM) technique. The humidity aging effect is evaluated based on the adhesive strength and CZM parameters. A lap joint test is carried out on the composite SLJ specimens, which are exposed for four months of 100% R.H. at $25^{\circ}C$. The predicted strengths are in good agreement with experimental data, and the actual crack propagation is satisfactorily simulated using the local CZM technique.

• Structural Engineering and Mechanics
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• v.89 no.1
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• pp.61-75
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• 2024

Strengthening of hollow structural sections using through-bolts is a cost-effective and straightforward approach. It's a versatile method that can be applied during both design and service phases, serving as a non-disruptive and budget-friendly retrofitting solution. Existing research on axially loaded hollow sections T-joints has demonstrated that this technique can amplify the joint strength by 50%, where single bolt could enhance the strength of the joint by 35%. However, there's a gap in understanding their use for K-joints. As the behavior of K-joints is more complex, and they are widely existent in structures, this study aims to bridge that gap by conducting comprehensive parametric study using finite element analysis. Numerical investigation was conducted to evaluate the effect of through bolts on K-joints focusing on using single through bolt to achieve most of the strengthening effect. A full-scale parametric model was developed to investigate the effect of various geometric parameters of the joint. This study concluded the existence of optimal bolt location to achieve the highest strength gain for the joint. Moreover, a rigorous statistical analysis was conducted on the data to propose design equations to predict optimal bolt location and the corresponding strength gain implementing the verified by finite element models.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.585-594
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• 2009

In this present study, to performed the model test and estimated the behavior characteristics of twin tunnel in accordance with the variation of the whole failure parameters which is the strength of the ground, distance of tunnel, angle of the joint, installation of tension bolts and the blasting load. To carry out the numerical analysis for verification of model test results and analyze the sensitivity on failure parameters using model test and numerical analysis results. Based on sensitivity analysis results, to propose the most habitually failure parameters in tunnel scale model test.