• Steel and Composite Structures
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• v.47 no.2
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• pp.289-296
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• 2023

The failure of a thin-walled tube was studied in this paper based on three failure models. Both proportional and non-proportional loading paths were applied. Proportional loading consisted of combined tension-torsion. Cyclic non-proportional loading was also applied. It was a circular out-of-phase axial-shear stress loading path. The third loading path was a combination of a constant internal pressure and a bending moment. The failure models under study were equivalent plastic strain, modified Mohr-Coulomb (Bai-Wierzbicki) and Tearing parameter models. The elasto-plastic analysis was conducted using J2 criterion and nonlinear kinematic hardening. The return mapping algorithm was employed to numerically solve the plastic flow relations. The effects of the hydrostatic stress on the plastic flow and the stress triaxiality parameter on the failure were discussed. Each failure model under study was utilized to predict failure. The failure loads obtained from each model were compared with each other. The equivalent plastic strain model was independent from the stress triaxiality parameter, and it predicted the highest failure load in the bending problem. The modified Mohr-Coulomb failure model predicted the lowest failure load for the range of the stress triaxiality parameter and Lode's angle.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.59 no.2
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• pp.135-144
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• 2023

In order to provide basic data to increase the efficiency and stability of seamanship at anchoring, the characteristics of the hull motion including dragging anchor due to external forces were observed at Mokpo and Jinhae anchorage for the avoidance of the typhoon. As a result, it is necessary to check the embedding motion and holding power of the anchor according to at initial position to decrease dragging anchor. Dragging anchor at anchorage seems to have been easily caused according to discrepancy between embedded anchor flukes and the towing direction due to the change in wind direction, rather than the wind speed. This discrepancy, thus, should be considered when anchoring. This test vessel with a small radius of curvature of the stem is relatively vulnerable to the influence of wind direction and wind speed, so it is easy to cause a decrease in the holding power due to an increase in the rate of turn. When the current speed is greater than or equal to 1 knot, the range of the rate of turn is reduced resulting in a relatively increased holding power. In addition, during the swing, the tension of the chain was high according to the angular velocity change of heading at three-quarters of the swing length rather than the left and right ends.

• Journal of Korean Medicine Rehabilitation
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• v.34 no.2
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• pp.173-180
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• 2024

Objectives The purpose of this study is to report the effects of Korean medicine treatment on tibia, fibula, and patellar fractures with sequelae of poliomyelitis. Methods A 64-year-old male patient was treated with acupuncture, herbal medicine, cupping, moxibustion, and exercise treatment for 59 days after open reduction and internal fixation and tension band wiring surgery. The effects were evaluated using a visual analog scale (VAS), manual muscle testing (MMT), range of motion (ROM), Western Ontario and McMaster Universities (WOMAC), and EuroQol-5 dimension (EQ-5D) index. Results After treatment, VAS decreased from 7 to 2. MMT, ROM, WOMAC, EQ-5D and walking ability were improved. Conclusions This case study suggests that Korean medicine treatment could be effective for tibia, fibula, patellar fractures in patients with sequelae of poliomyelitis.

• Journal of the Korean Society of Industry Convergence
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• v.27 no.3
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• pp.555-561
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• 2024

This paper derives material properties of steel bars that simulate the distribution of stress and strain of prestressed tendons used in Prestressed concrete(PSC) girders and presents an optimal material model. ABAQUS software was used to establish the 3D solid model of the PSC girder and strand wire rope for a PS(Prestressed) tendon. Then the model of steel wire rope was imported into the Isight interface plugin directly through the ABAQUS and the Data Matching. In ABAQUS, the contact pairs were established, the models were meshed, the constraints were applied to solve the finite element model and an axial tension of 0.5m/s was loaded to analyze the stress and deformation distributions in the normal working range of the PS strand wire rope. In Data Matching, classical experimental data is fitted to the optimal material properties through finite element analysis and multi-objective optimization. The results show that the steel bar with optimal material properties presents a similar linear area and stress distribution with the PS tendon.

• The korean journal of orthodontics
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• v.28 no.5 s.70
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• pp.699-716
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• 1998

This study was designed to evaluate the expression of non-collagenous protein in periodontal tissue during the experimental movement of rat incisors, by LSAB(labelled streptavidine biotin) immunohistochemical staining for osteonectin and osteocalcin. Twenty seven Sprague-Dawley rats were divided into a control group(3 rats) and 6 experimental groups(24 rats) where 75g of force was applied from helical springs across the maxillary incisors. Rats of experimental groups were sacrificed at 12 hours, 1, 4, 7, 14 and 28 days after force application, respectively. And the tissues of a control group and experimental groups were studied immunohistochemically and histologically. The results were as follows : 1. Until 28 days after force application, periodontal fibers had been strectched on tension side and compressed in pressure side of all the experimental groups, and the arrangement of periodontal fibers had not been recovered yet. 2. The expression of osteonectin in control group was rare in dentin, cementum and osteocyte, and was mild in odontoblasts and matrix of alveolar bone. 3. The expression of osteocalcin in control group was negative in gingiva, osteoblasts, osteocyte and cementum, and was rare in predentin, capillaries in pulp and periodontal ligament and the matrix of alveolar bone. 4. There was no difference in the expression of osteocalcin or osteonectin in dentin, cementum, pulp, odontoblasts, between of control and of experimental groups. 5. The expression of osteonectin in intermaxillary suture got the peak in 7-day and was declined after 14-day. The expression of osteocalcin remained in a same degree since it became mild in 14-day. 6. The expression of osteonectin in pressure side of periodontal ligament of experimental group was rare, which was similar to control group. But in tension side, it was increased until 14-day aftrer which it was declined. 7. The expression of osteocalcin in periodntal ligament was rare in 12-hour to 14-day, but became severe in 28-day, which was greater in tension side than in pressure side, and in the periodontal fiber next to alveolar bone than to tooth surface. 8. The expression of osteocalcin in alveolar bone was rare until 14-day in pressure side, but became moderate in 28-day. The expression of osteonectin was increased from 7-day by time dependency, which was greater in tension side than in pressure side.

• The Korean Journal of Physiology and Pharmacology
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• v.2 no.6
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• pp.695-703
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• 1998

$[K^+]_o$ can be increased under a variety of conditions including subarachnoid hemorrhage. The increase of $[K^+]_o$ in the range of $5{\sim}15$ mM may affect tensions of blood vessels and can change their sensitivity to various vasoactive substances. Therefore, it was examined in the present study whether the sensitivity of cerebral arteries to vasoactive substances can be changed with the moderate increase of $[K^+]_o$, using Mulvany-type myograph and $[Ca^{2+}]_c$ measurement. The contractions of basilar artery and branch of middle cerebral artery induced by histamine were not increased with the elevation of $[K^+]_o$ from 6 mM to 9 mM or 12 mM. On the contrary, the contractions induced by serotonin were significantly increased with the elevation of $[K^+]_o$. The contractions were also significantly increased by the treatment with nitro-L-arginine $(10^{-4}$ M for 20 minutes). In the nitro-L-arginine treated arteries, the contractions induced by serotonin were significantly increased with the elevation of $[K^+]_o$ from 6 mM to 12 mM. $K^+-induced$ relaxation was evoked with the stepwise increment of extracellular $K^+$ from 0 or 2 mM to 12 mM by 2 mM in basilar arterial rings, which were contracted by histamine. But $[K^+]_o$ elevation from 4 or 6 mM to 12 mM by the stepwise increment evoked no significant relaxation. Basal tension of basilar artery was increased with $[K^+]_o$ elevation from 6 mM to 12 mM by 2 mM steps or by the treatment with ouabain and the increase of basal tension was blocked by verapamil. The cytosolic free $Ca^{2+}$ level was not increased by the single treatment with serotonin or with the elevation of $[K^+]_o$ from 4 mM to 8 or 12 mM. In contrast to the single treatment, the $Ca^{2+}$ level was increased by the combined treatment with serotonin and the elevation of $[K^+]_o$. The increase of free $Ca^{2+}$ concentration was blocked by the treatment with verapamil. These data suggest that the sensitivity of cerebral artery to serotonin is increased with the moderate increase of $[K^+]_o$ and the increased sensitivity to serotonin is due to the increased $[Ca^{2+}]_i$ induced by extracellular $Ca^{2+}$ influx.

• The Korean Journal of Physiology and Pharmacology
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• v.15 no.6
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• pp.339-344
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• 2011

Ulmus davidiana var. japonica Rehder (Urticales: Ulmaceae) (UD) is a tree widespread in northeast Asia. It is traditionally used for anticancer and anti-inflammatory therapy. The present study investigated the effect of an ethanol extract of UD on vascular tension and its underlying mechanism in rats. The dried root bark of UD was ground and extracted with 80% ethanol. The prepared UD extract was used in further analysis. The effect of UD on the cell viability, vasoreactivity and hemodynamics were investigated using propidium iodide staining in cultured cells, isometric tension recording and blood pressure analysis, respectively. Low dose of UD ($10{\sim}100{\mu}g/ml)$ did not affect endothelial cell viability, but high dose of UD reduced cell viability. UD induced vasorelaxation in the range of $0.1{\sim}10{\mu}g/ml$ with an $ED_{50}$ value of $2{\mu}g/ml$. UD-induced vasorelaxation was completely abolished by removal of the endothelium or by pre-treatment with L-NAME, an inhibitor of nitric oxide synthase. UD inhibited calcium influx induced by phenylephrine and high $K^+$ and also completely abolished the effect of L-NAME. Intravenous injection of UD extracts (10~100 mg/kg) decreased arterial and ventricular pressure in a dose-dependent manner. Moreover, UD extracts reduced the ventricular contractility (+dP/dt) in anesthetized rats. However, UD-induced hypotensive actions were minimized in L-NAME-treated rats. Taken together, out results showed that UD induced vasorelaxation and has antihypertensive properties, which may be due the activation of nitric oxide synthase in endothelium.

• The Korean Journal of Physiology
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• v.23 no.1
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• pp.139-149
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• 1989

Although tail flick reflex (TFR) in rats has been used as a classic model of the nociceptive test to evaluate the action of analgesics, there have been few studies on the origin of the latent period of TFR. Present study was performed to elucidate the mechanism of increase in latency of TFR by morphine in anesthetized rats. Tail skin and dorsolateral tail nerve were stimulated electrically and EMG activities were recorded from abductor caudae dorsalis muscle participating in tail flick reflex. In the case of noxious radiant heat stimulation to tail, the tail flick tension was recorded before and after administration of morphine. Then changes in latency and conduction velocity of peripheral nerve were evaluated. The results obtained were as follows: 1) The latencies of TFR evoked by the electrical stimulation of tail skin and dorsolateral tail nerve were all within 40 ms and were elongated by several milliseconds from control after the administration of morphine. Peripheral conduction velocities of tail flick afferent nerve were within the range of 10-25 m/s. 2) The conduction velocity of peripheral nerve was significantly reduced after morphine administration, therefore the afferent time (utilization time+conduction time to spinal cord) was significantly increased. But the time for central delay and efferent time was not affected by morphine. 3) The conduction velocity under room temperature $(20-25^{\circ}C)$ was significantly reduced after morphine while that under vasodilation state $(40{\sim}42^{\circ}C)$ increased, 30 min and 45 min after morphine. The conduction velocity under vasodilation state without treatment of morphine increased continuously 4) The latency in tension response of TFR evoked by electrical stimulation was elongated by several milliseconds from control while the latency evoked by noxious radiant heat was elongated by several seconds compared with that of control. From the above results, it could be concluded that: 1) the increased latency of TFR evoked by electrical stimulation of the tail after morphine administration was due to the reducton in conduction velocity of peripheral nerve, which was the secondry effect of morphine on the peripheral vasomotion and 2) increased latency of TFR evoked by noxious radiant heat was also due to the same effect of morphine and the increase in cutaneous insulation to the noxious heat.

• Applied Chemistry for Engineering
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• v.31 no.4
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• pp.429-437
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• 2020

In this study, a cationic gemini surfactant was synthesized using isosorbide, in order to modify the alkyl chain length in the range of C₁₀~C₁₆. The c.m.c and surface tension of the synthesized cationic gemini surfactant were measured to be in the ranges of 5.13 × 10^-4~1.62 × 10^-4 mol/L and 31.86~37.41 dyne/cm, respectively. The surface tension increased with increasing the length of the alkyl group. In addition, as the area per molecule occupied by the surfactant adsorbed on the interface increased with the reduced extent of adsorption, the bubble generation at the air-water interface decreased. The emulsifying capacity in benzene was maintained above 60 ± 5% after 8 h while that in soybean oil tended to decrease above 50 ± 5%. The performance was superior in benzene, a highly hydrophobic substance, and the emulsion stability was shown to be consistent beyond 1 h during the preparation of pre-emulsion in oil and water. The antimicrobial activity was dependent on the length of the hydrophobic chain of the synthesized cationic gemini surfactant due to the increased size of the clean zone in Escherichia coli (E.coli) and Staphylococcus aureus.

• Journal of Korean Society of Steel Construction
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• v.18 no.6
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• pp.697-706
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• 2006

Tower crane's wall tie is generally used for extending of mast height according to rising of lifting height. In order to get wall tie member force this problem, this study concerning wall tie is based on load data described in manual book of 290HC model. This study made the equation of wall tie member force and computer programming for calculating wall tie member force and then get ${\theta}-P$ curves(angle-wall tie force). After considering the ${\theta}-P$ curves, optimum angle range ($48.4^{\circ}{\sim}77.2^{\circ}$) about wall ties (A), (C) members was obtained. Member force of wall tie (B) was changed from tension to compression or from compression to tension at $74^{\circ}$ in service and $54^{\circ}$ in out of service. When both horizontal force($H_A$) and torsional moment ($M_D$) were varied from (+) to (-), wall tie force(A, B, C) were changed almost symmetrically about ${\theta}$-axis. Because this study was based on wall tie analysis conditions, wall tie members in symmetric and ideal geometry shape used for analizing wall tie of tower crane, it is necessary to have more careful verification in order to apply generally the results of this study.