• Tunnel and Underground Space
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• v.26 no.5
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• pp.384-395
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• 2016

Both the roughness measurement tests and the multi-stage shear tests were carried out on the 110 rock joint samples in order to investigate the influences of rock type, joint roughness and normal stress on the shear behaviour of rock joints. Test samples were composed of quartz porphyry, dacite, granite and gneiss, which were classified into three detailed groups according to their JRC values. Roughness parameters of rock joints were analyzed by roughness measurement tests, and shear characteristics were also investigated by multi-stage shear tests. Both peak shear strength and shear stiffness were increased as both joint roughness and normal stress were increased, whereas dilation angles showed lower values at the lower roughness and higher normal stress conditions. Besides, shear characteristics obtained from all tests of four different rock types with different rock strengths showed irrelevant details, therefore the influences of both joint roughness and normal stress on shear behaviors were found to be more considerable than the strength of intact rock. The results obtained from both multi-stage shear tests and direct shear tests were finally compared, where the dilation angles obtained from multi-stage shear tests were found to be valid only for the first normal stress conditions.

• Journal of the Korean Society for Precision Engineering
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• v.5 no.3
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• pp.20-30
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• 1988

Using the design parameters of multi-joint manipulator, worspace of the manipulator were evaluated analytically, and the relation between such design parameters and nonlinearity of the manipulator were presented dynamically. The ratio of the volumes of a manipulator's workspace to the cube of its total link length presents a kinematic performance index [NVI] for the manipullator. It is possible to geometrically represent the manipulator dynamics with the generalized inertia ellipsoid (GIE). The relation between the GIE configuration and the characteristics of manipulator dynamics was analysed in terms of inertia and nonlinear forces (Coliolis and centrifugal forces). The nonlinearity caused by the change of the GIE configuration were affected by the difference between the major and minor axes length of the GIE. The results of this investigationare applied to the optimal design of the manipulator.

• Journal of the Korea Institute of Military Science and Technology
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• v.13 no.3
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• pp.461-469
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• 2010

In this paper, we have proposed an improved fusion method of detection features which can enhance the detection probability under the given false alarm rate in the prescreening stage of SAR ATR(Synthetic Aperture Radar Automatic Target Recognition) system. Since the detection features have the positive correlation, the detection performance can be improved if the joint probability distribution of detection features is considered in the fusion process. The detection region is designed as a simple piecewise linear function which can be represented by few parameters. The parameters for the detection region can be derived by training the sample SAR images to maximize the detection probability with the given false alarm rate. Simulation result shows that the detection performance of the proposed method is improved for all combinations of detection features.

• Journal of Information Processing Systems
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• v.13 no.1
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• pp.83-94
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• 2017

Near-field source localization algorithms are very sensitive to sensor gain/phase response errors, and so it is important to calibrate the errors. We took into consideration the uniform linear array and are proposing a blind calibration algorithm that can estimate the directions-of-arrival and range parameters of incident signals and sensor gain/phase responses jointly, without the need for any reference source. They are estimated separately by using an iterative approach, but without the need for good initial guesses. The ambiguities in the estimations of 2-D electric angles and sensor gain/phase responses are also analyzed in this paper. We show that the ambiguities can be remedied by assuming that two sensor phase responses of the array have been previously calibrated. The behavior of the proposed method is illustrated through simulation experiments. The simulation results show that the convergent rate is fast and that the convergent precision is high.

• Biomolecules & Therapeutics
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• v.22 no.3
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• pp.260-266
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• 2014

This study evaluated the pharmacokinetic profile and therapeutic efficacy of piroxicam (PX), a long acting non-steroidal anti-inflammatory drug for the treatment of arthritis, following intra-articular (IA) injection in comparison to the pharmacokinetic profile and therapeutic efficacy of PX after intramuscular (IM) injection. In the pharmacokinetic study in rats, systemic exposure and pharmacokinetic parameters of PX after a single IA dose were compared with systemic exposure and pharmacokinetic parameters of PX after administration of the same dose IM (0.6 mg/kg). The anti-inflammatory and analgesic effects of IA PX were evaluated simultaneously in a monoiodoacetate-induced osteoarthritis rat model. The plasma PX concentration rapidly rose following IA injection, and it was comparable to the plasma PX concentration following IM injection, suggesting the rapid efflux of the drug molecule from the joint cavity. However, in the efficacy study, the IA PX administration significantly reduced the knee swelling by reducing the level of prostaglandin $E_2$ in the joint, compared to that following administration of IA vehicle and after administration of the IM PX dose. In addition, we found that the anti-inflammatory and anti-nociceptive efficacies of IA PX were synergistically increased upon co-treatment with hyaluronic acid (HA), a potent agent for the treatment of osteoarthritis, at the weight ratio of 1:1 or 1:2, and these effects were more pronounced than those following administration of HA or PX alone. In conclusion, this study demonstrated the efficacy of the IA use of PX alone and/or in combination with HA in osteoarthritis.

• Journal of the Korean Society for Heat Treatment
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• v.24 no.5
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• pp.277-286
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• 2011

The spot weldability of metal joints between SD35 and SD30A steel was investigated. This study was aimed to determine the spot welding parameters (i.e. welding current and time) for reinforcement bar joint and to evaluate the weldability, mechanical strength, hardness and microstructure. The results indicated that shear strength and elongation of the welding joints at 12.5kA and 1000 ms were 26.7 $kgf/mm^2$ and 22%, respectively. And fracture distribution of them by using shear and tensile test showed 100% necking mode and 100% ductile mode, respectively.

• Journal of muscle and joint health
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• v.1 no.1
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• pp.1-30
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• 1994

Rheumatoid arthritis is a chronic systematic disease with unpredictable course of exacerbation and remission, characterized by pain, joint deformity and reduced activity by joint limitation. The growing public awareness of the need for health management of chronic illnesses, provides impetus for nursing to demonstrate social effectiveness by active nursing intervention in this vast area in general, and with rheumatoid condition in particular. However, nursing interventions to date have not demonstrated its active participation in the management of chronic conditions. Nursing intervention for the patients having rheumatoid arthritis is one such area that needs to be studied intensively and to demonstrate their effectiveness empirically. The purposes of this study were two fold : first, to develop a comprehensive program that was intensified with therapeutic joint exercises in water, self-help group activities and utilization of self-efficacy promoting strategies : and secondly, to determine the effect of aquatic exercise program on pain, physiological changes and quality of life in the rheumatoid arthritis patients. Thirty five female subjects participating in this study were selected from outpatients in the Rheumatism Center, Hanyang University hospital. The period of data collection was from December, 1992 to March, 1993 in seoul and Taejeon. Subjects in Taejeon were assigned to the experimental group. The comprehensive aquatic exercise program for the experimental group was carried out three times a week for 6 weeks in regular swimming pool. Subjects in Seoul did not participated in the program, and treated as the control group. Data were analyzed with repeated measure MANCOVA, t-test, ANCOVA, percentage of change, Kruskal-Wallis 1-Way ANOVA using SPSS $PC^+$ program. Results were obtained as follows : 1) Scores on Korean pain scale, Numeric pain score, and RAI score of the experimental group were significantly lower than those of the control group (t=2.11, p=0.022 ; F=4.40, p=0.044 : t=3.10, p=0.002). 2) There was significant improvement in the physiological parameters (higher joint movement parameters, F=15.64, p=0.024 ; higher lean body mass, percentage of change=+12.2, lower body weight, t=1.01, p=0.026 : lower ESR, t=1.69, p=0.001) in the experimental group compaired with subjects In the control group. 3) There was significant improvement in the specific self-efficacy score through the comprehensive aquatic exercise program(t=2.73, p=0.011), but not in the general self- efficacy score(t=0.62, p=0.113). 4) The quality of life failed to show significant improvement in the experimental group as compaired with the control group (F=3.69, p=0.064). 5) In the experimental group, findings from additional analysis showed no significant difference in the specific self-efficacy between those who continued to aquatic exercise after completing 6 week program and those who stopped (X2=0.086, p=0.690). Therefore, adherence to aquatic exercise program for 6 weeks seem to be affected mainly by self-help group activities. An indepth study to delve into articulation of mechanisms affecting the effect of aquatic exercise program be recommended. A further study is necessary to determine the difference in the effect of group and individual aquatic exercise program, to assess factors affecting adherence to exercise for an extended length of time.

• Journal of Biomedical Engineering Research
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• v.37 no.1
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• pp.21-30
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• 2016

Weibull distribution with two parameters, shape (k) and scale (s) parameters are used to model the fatigue failure analysis due to periodic vortex shedding of the synovial fluid in knee joints. In order to determine the later parameter, a suitable statistical model is required for velocity distribution of synovial fluid flow. Hence, wide applicability of Weibull distribution in life testing and reliability analysis can be applied to describe the probability distribution of synovial fluid flow velocity. In this work, comparisons of three most widely used methods for estimating Weibull parameters are carried out; i.e. the least square estimation method (LSEM), maximum likelihood estimator (MLE) and the method of moment (MOM), to study fatigue failure of bone joint due to periodic vortex shedding of synovial fluid. The performances of these methods are compared through the analysis of computer generated synovial fluidflow velocity distribution in the physiological range. Significant values for the (k) and (s) parameters are obtained by comparing these methods. The criterions such as root mean square error (RMSE), coefficient of determination ($R^2$), maximum error between the cumulative distribution functions (CDFs) or Kolmogorov-Smirnov (K-S) and the chi square tests are used for the comparison of the suitability of these methods. The results show that maximum likelihood method performs well for most of the cases studied and hence recommended.

• Journal of Welding and Joining
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• v.30 no.6
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• pp.126-132
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• 2012

The GMA welding process involves large number of interdependent variables which may affect product quality, productivity and cost effectiveness. The relationships between process parameters for a fillet joint and bead geometry are complex because a number of process parameters are involved. To make the automated GMA welding, a method that predicts bead geometry and accomplishes the desired mechanical properties of the weldment should be developed. The developed method should also cover a wide range of material thicknesses and be applicable for all welding position. For the automatic welding system, the data must be available in the form of mathematical equations. In this study a new intelligent model with genetic algorithm has been proposed to investigate interrelationships between welding parameters and bead geometry for the automated GMA welding process. Through the developed model, the correlation between process parameters and bead geometry obtained from the actual experimental results, predicts that data did not show much of a difference, which means that it is quite suitable for the developed genetic algorithm. Progress to be able to control the process parameters in order to obtain the desired bead shape, as well as the systematic study of the genetic algorithm was developed on the basis of the data obtained through the experiments in this study can be applied. In addition, the developed genetic algorithm has the ability to predict the bead shape of the experimental results with satisfactory accuracy.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.320-320
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• 2016

Nanocrystalline Carbon thin films have numerous applications in different areas such as mechanical, biotechnology and optoelectronic devices due to attractive properties like high excellent hardness, low friction coefficient, good chemical inertness, low surface roughness, non-toxic and biocompatibility. In this work, we studied the comparison of pure DC power and pulsed DC power in plasma sputtering process of carbon thin films synthesis. Using a close field unbalanced magnetron sputtering system, films were deposited on glass and Si wafer substrates by varying the power density and pulsed DC frequency variations. The plasma characteristics has been studied using the I-V discharge characteristics and optical emission spectroscopy. The films properties were studied using Raman spectroscopy, Hall effect measurement, contact angle measurement. Through the Raman results, ID/IG ratio was found to be increased by increasing either of DC power density and pulsed DC frequency. Film deposition rate, measured by Alpha step measurement, increased with increasing DC power density and decreased with pulsed DC frequency. The electrical resistivity results show that the resistivity increased with increasing DC power density and pulsed DC frequency. The film surface energy was estimated using the calculated values of contact angle of DI water and di-iodo-methane. Our results exhibit a tailoring of surface energies from 52.69 to $55.42mJ/m^2$ by controlling the plasma parameters.