• Journal of Dental Rehabilitation and Applied Science
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• v.31 no.1
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• pp.26-32
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• 2015

Purpose: The main purpose of this study is to suggest application plan of dipping method by comparing & analysing the difference between addition method and dipping method in the manufacture of metal-ceramic substructure of maxillary central incisor (#1), followed by assessing the work efficiency. Materials and Methods: Master die and hard plaster-copied one were produced and then a total of 20 copies, 10 copies for each through addition method and dipping method, were manufactured and experimented. Copings were fixed on the abutment model and invested in epoxy mounting cup. Samples were cut in labial and lingual direction, using cutter and then rubbed on sandpaper, whose 4 points were measured by using digital microscope. Results: The comparison of mean values by using t-test, parametric statistical method, shows overall significant difference (P < 0.05). Conclusion: The result of this study can be suggested as an application plan, since there is no significant difference between addition method and dipping method in the manufacture of metal-ceramic substructure.

• Journal of Adhesion and Interface
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• v.9 no.3
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• pp.20-26
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• 2008

It is well know that the structure of shape memory alloy (SMA) can change from martensite austenite by either temperature or stress. Due to their inherent shape recovery properties, SMA fiber can be used such as for stress or cure-monitoring sensor or actuator, during applied stress or temperature. Incomplete superelasticity was observed as the stress hysteresis at stress-strain curve under cyclic loading test and temperature change. Superelasticity behavior was observed for the single-SMA fiber/epoxy composites under cyclic mechanical loading at stress-strain curve. SMA fiber or epoxy embedded SMA fiber composite exhibited the decreased interfacial properties due to the cyclic loading and thus reduced shape memory performance. Rigid epoxy and the changed interfacial adhesion between SMA fiber and epoxy by the surface treatment on SMA fiber exhibited similar incomplete superelastic trend. Epoxy embedded single SMA fiber exhibited the incomplete recovery during cure process by remaining residual heat and thus occurring residual stress in single SMA fiber/epoxy composite.

• Clinical and Experimental Pediatrics
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• v.50 no.6
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• pp.580-584
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• 2007

Multiple sclerosis (MS) is a demyelinating disorder that affects discrete areas of the CNS, including the optic nerves, in a quite variable relapsing-remitting fashion over a prolonged period of time. Although MS is usually considered to be a disease that affects peoples in early to middle adulthood, children do develop multiple sclerosis. The frequency of MS onset before the age of 15 years is 2.7-5% of all cases, while MS onset during infancy and early childhood was observed to be 0.2-0.7% of all cases. We report here on a Korean case of a relapsing-remitting MS female child who was treated with four rounds of intravenous methylpredinsolone pulse therapy and preventive Interferon-$\beta$-1b ($Betaferon^{(R)}$).

• Journal of the Korean Geotechnical Society
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• v.21 no.8
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• pp.27-35
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• 2005

Several damages due to large displacement caused by liquefaction have been reported increasingly. Numerical procedures based on effective stress analysis are therefore necessary to predict liquefaction-induced deformation. In this paper, the fully coupled effective stress model called UBCSAND is proposed to simulate pore pressure rise due to earthquake or repeated loadings. The proposed model is a modification of the simple perfect elasto-plactic Mohr-Coulomb model, and can simulate a continuous yielding by mobilizing friction and dilation angles below failure state. Yield function is defined as the ratio of shear stress to mean normal stress. It is radial lines on stress space and has the same shape of Mohr-Columob failure envelope. Plastic hardening is based on an isotropic and kinematic hardening rule. The proposed model always causes plastic deformation during loading and reloading but it predicts elastic unloading. It is verified by capturing direct simple shear tests on loose Fraser River sand.

• Tuberculosis and Respiratory Diseases
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• v.44 no.1
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• pp.85-92
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• 1997

Background : The standard treatment of recurrent, symptomatic malignant pleural effusion is intrapleural instillation of a chemical agent in an attempt to achieve a sterile inflammation and pleurodesis. There are many drugs used as pleural sclerosing agents, but the efficiency and side effects are different. The present study was undertaken to compare the commonly used drugs, doxycycline and bleomycin. Methods : Thirty-four patients with malignant pleural effusion who needed repeated thoracentesis were randomized to receive treatment with intrapleural instillation of doxycycline or bleomycin Fluid volumes before and after pleurodesis, drainge time, and side effects were analyzed, and the response to treatment was evaluated by clinical examination and chest radiography during admission in the hospital. Also median survival rime were evaluated according to the responses. Results : The response rate was higher in the patients receiving doxycycline than in those receiving bleomycin (87.5% vs 50.0%, p=0.02), and fever, nausea and vomiting were more common in the patients receiving bleomycin. The median survival time was significantly longer in the patients who responded to the sclerotherapy regardless of sclerosing agents. Conclusions : Chemical pleurodesis with doxycycline or bleomycin could reduce or stop pleural effusions and prolong the median survival rimes in these patients. Doxycycline appeared to be more efficient as sclerosing agent than bleomycin in the short-term follow-up periods. But a prospective study with a larger number of patients is warranted.

• Journal of the Korean Applied Science and Technology
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• v.35 no.4
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• pp.1185-1196
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• 2018

The purpose of this study was to investigate the effects of 12-week aquarobics exercise on blood lipids, atherogenic index, and liver functions in elderly women. The subjects for the study were 25 healthy elderly women volunteers, aged 65 to 80 years, composed of the aquarobics exercise group (n=13) and control group (n=12). Twice a week for 60 minutes for 12 weeks. The exercise intensity was set to RPE 11-12 for 1 week to 4 weeks, RPE 13-14 for 5 week to 8 weeks and RPE 15-16 for 9 week to 12 weeks respectively. The test data were analyzed by two-way repeated measures ANOVA, paired t-test, and independent t-test. The alpha level of .05 was set for all tests of significance. The results of the study in the aquarobics exercise group were as follows; LDL-C (p<.05), AST (p<.05) had significantly decreased, with TC (p<.01), TG (p<.05), LDL-C (p<.05), LDL-C/HDL-C (p<.05), TG/HDL-C (p<.05), AST (p<.001) significantly lower than control group. Consequently, these findings suggest that regular aquarobics exercise will be effective for preventiy the metabolic syndrome and cardiovascular health in elderly women.

• Journal of the Korean Applied Science and Technology
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• v.38 no.6
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• pp.1512-1523
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• 2021

The purpose of this study was to investigate the effect of Saengmaeg-san intake on blood lipids and arteriosclerosis index in male tennis players. Seventeen male tennis players enrolled in university were assigned to a Saengmaeg-san intake group (n=9) and a placebo control group (n=8) according to whether they took Saengmaeg-san during 4-week high-intensity tennis training. Tennis training was conducted 5 times a week for 4 weeks, and the exercise intensity was performed at 70-90% of the spare heart rate. The intake of Saengmaeg-san was 110ml at a time before breakfast, before, during, during, and after exercise, and after dinner, a total of 7 times, 770ml per day. For all data, mean and standard deviation were used. Two-way repeated measures ANOVA was used to examine the effect of time and treatment, and Pearson's Correlation was used to examine the relevance of differences in blood lipid responses after treatment. As a result of this study, the Saengmaeg-san intake group significantly improved blood lipids (triglyceride, total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol) and arteriosclerosis index, and there was a significant correlation appeared between ∆TG, ∆LDL-C, and ∆TC. As a result, the intake of Saengmaeg-san during high-intensity training of male college student tennis players can have a positive effect on blood lipids and arteriosclerosis index, suggesting that it can be an effective sports drink as an exercise supplement.

• Journal of Korean Society of Steel Construction
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• v.14 no.6
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• pp.735-746
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• 2002

The task of plastic theory is twofold: first, to set up relationships between stress and strain that adequately describe the observed plastic deformation of metals, and second, to develop techniques for using these relationships in studying of the mechanics of metal forming processes, and the anlaysis and design of structures. One of the major problems in the theory of plasticity is to describe the behavior of work-hardening materials in the plastic range for complex loading histories. This can be achieved by formulating constitutive laws either in the integral or differential forms. To adequately predict the response of steel members during cyclic loading, the hardening rule must account for the features of cyclic stress-strain behavior. Neithe of the basic isotropic and kinematic hardening rules is suitable for describing cyclic streess-strain behavior, although a kinematic hardening rule describes the nearly linear portions of the stabilized hystersis loops. There is also a limited expansion of the yield surface as predicted by the isotropic hardening rule. Strong ground motions or wind gusts affect the complex and nonproportional loading histories in the inelastic behavior of structues rather than the proportional loading. Nonproportional loading is defined as externally applied forces on the structure, with variable ratios during the entire loading history. This also includes the rate of time-dependency of the loads. For nonproportional loading histories, unloading may take place along a chord instead of the radius of the load surface. In such cases, the shape of the stress-strain curve has to be determined experimentally for all non-radial loading conditions. The plasticity models including two surface models ae surveyed based on a yield surface and a bound surface that represent a state of maximum stress. This paper is concerned with the improvement of a plasticity models of the two-surface type for structural steel. This is follwed by an overview of plasticity models on structural steel. Finally the need for further research is identified.

• Magazine of the Korea Concrete Institute
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• v.10 no.6
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• pp.291-301
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• 1998

In this paper, two dimensional and three dimentional modeling techniques are proposed for the failure analysis of deteriorated reinforced concrete T-girder bridge subjected to cyclic loading up to failure. For the nonlinear failure anaysis, a tension stiffening model which can consider degradation of bond between reinforcement and surrounding concrete due to corrision of rebars in old bridge is proposed and a modeling technique for the supports conditions of the bridges which can consider degradation of bearing at supports in old bridge is also proposed, The analysis results along with comparisons with full-scale failure-test results confirm that finite element modeling techniques in this paper can be well applied to the failure analyses of in-situ old reinforced concrete T-girder bridges subjected to cyclic loading and the support condition modeling especially affects the bridge strength significantly.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.16 no.2
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• pp.58-67
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• 2020

This study presents cyclic stress-strain and tensile test results at room temperature (RT) and 316℃ using cold-worked TP304 stainless steel base and weld metals. By comparing the cyclic hardening/softening behavior and failure cycle of cold-worked materials with those of irradiated austenitic stainless steels, the feasibility of simulating the irradiation effect on cyclic deformation and failure behaviors of TP304 stainless steel base and weld metals was investigated. It was found that, in the absence of strain-induced martensite trasformation, cold-working could properly simulate the change in cyclic hardening/softening behavior of TP304 stainless steel base and weld metals due to neutron irradiation. It was also recognized that cold-working could adequately simulate the reduction in failure cycles of TP304 stainless steel base and weld metals due to neutron irradition in the low-cycle fatigue region.