• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.21 no.5
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• pp.461-467
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• 2011

This study aims to create a numerical analysis model which can investigate the dynamic interaction between pantograph and overhead contact wire used for a high-speed railway vehicle, and validate the simulation results according to EN 50318 standard. Finite element analysis models of pantograph and overhead contact line are created using SAMCEF, a commercial FE analysis program. The mean, standard deviation, maximum and minimum values of contact forces are obtained. The simulation results are validated according to EN 50318, and the possibility of simulating the collecting characteristic of an actual pantograph system by using the developed model is discussed.

• Journal of the Korean Society for Railway
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• v.12 no.5
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• pp.732-737
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• 2009

Wind tunnel testing on the real-scale pantograph for high-speed train has been conducted to investigate the aerodynamic characteristic of the pantograph at high-speed. The mid-scale subsonic wind tunnel of Korea Airforce Acamedy with 3.5m width, 2.45m height, and 8.8m length test section has been employed. The test model has been supported above 50cm height from the bottom of test section using vertical strut to eliminate the boundary layer generated from the bottom of the test section. The height of the pantograph has been varied in three cases, in both of the normal running and reverse running modes. The resultant lift forces of the pantograph to catenary system in all the cases have been measured and the relation between the test conditions and the lift forces have been extensively analyzed.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.27 no.5
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• pp.315-323
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• 2015

Damage level of coastal structures has been scaled up according to increase of wave height and duration of the storm due to the abnormal global climate change. So, the design criteria for new breakwaters is being intensified and structural strengthening is also conducted for the existing breakwaters. Recently, interlocking concept has been much attention to enhance the structural stability of the conventional caisson structure designed individually to resist waves. The interlocking caisson breakwater may be survival even if unusual high wave occurs because the maximum wave force may be reduced by phase lags among the wave forces acting on each caisson. In this study, the dispersion characteristics of wave forces using interlocking system that connect the upper part of caisson with cable in the normal direction of breakwater was investigated. A simplified linear model was developed for computational efficiency, in which the foundation and connection cables were modelled as linear springs, and caisson structures were assumed to be rigid. From numerical experiments, it can be found that the higher wave forces are transmitted through the cable as the angle of incident wave is larger, and the larger the stiffness of the interlocking cable makes larger wave dispersion effect.

• Korean Journal of Acupuncture
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• v.34 no.4
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• pp.265-270
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• 2017

Objectives : The present study aimed to examine the analgesic effect of electroacupuncture(EA) applied to the brook point of the Liver meridian in the rat model of inflammatory pain and to investigate involvement of endogenouse opioid in the EA-induced analgesia. Methods : Knee arthritis was induced by injection of $125{\mu}l$ of complete Freund's adjuvant into the knee joint cavity unilaterally. To examine the level of pain, weight bearing forces(WBFs) of affected limb was measured. EA treatment was given at the LR2, LI4 or non-acupoint on the contralateral limb with frequency of 2 Hz and intensity of 2 mA under gaseous anesthesia. Results : After induction of arthritis, rats subsequently showed a reduced stepping force of the affected hindlimb due to a painful knee. EA applied to the LR2 point on the contralateral hind limb produced a significant improvement of stepping force of the hind limb lasting for at least 2 h, and this effect was equivalent to that obtained by 5 mg/kg of oral indomethacin. The effect of EA was specific to the acupoint since it could not be mimicked by EA applied to the LI4 point or the arbitrary non-acupoint. The analgesic effect was blocked by pretreatment with naltrexone(10 mg/kg, i.p.). Conclusions : These results suggest that acupuncture applied to LR2, brook point of Liver meridian suppresses inflammatory pain in a rat model of knee arthritis and this effect seems to be mediated by endogenous opioid systems.

• Journal of Korean Society of Steel Construction
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• v.12 no.5 s.48
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• pp.527-535
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• 2000

Accurate determination of the relative restraint of beam-to-column connections is important for both the strength and the serviceability of structural frames. But steel frame analysis is carried out under the assumption that the connections are either fixed or pinned. Overestimating the connection restraint can result in underestimating lateral sway and underestimating the connection restraint can lead to underestimating forces developed in the beams and columns. This implies that the exact stiffness of connections as well as the geometric effects should be considered in the frame analysis and the overall behavior of connections could be described adequately. Therefore, the stiffness matrix which is able to consider the moment-rotation of connection was derived previously and the modified exponential model, power model and the proposed log model are adopted for modeling the semi-rigid connections. The main purpose of this study is to examine the feasibility of the derived stiffness matrix and to show the validity of log model proposed.

• The korean journal of orthodontics
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• v.29 no.5 s.76
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• pp.521-534
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• 1999

The purpose of this study was to find the difference of stress distribution on canine altered by the application point of preangulated T-loop spring. For this study, the finite element models of upper left canine, upper left second premolar and upper left first molar were made. Also, the finite element models of $0.017{\times}0.025$ inch preangulated, preactivated T-loop spring and $0.018{\times}0.025$ inch stainless steel wire were made. Three types of T-loop spring were made . the middle of activated T-loop is positioned in accordance with the middle position of distance of bracket position of both the canine and first molar, 2mm anterior, 2mm posterior. We compared the forces and the distribution of stress that were generated by the difference of position of T-loop spring. The results were as follows. 1. All of the 3 types of T-loop spring showed the similar retraction forces. 2. All showed the similar amount & pattern of stress distribution. 3. The centers of rotation of canine in 3 types of T-loop spring were same and were positioned between C and D plane. 4. The canine showed the intrusive force by 2mm anterior positioned T-loop spring, but the extrusive force by 2mm posterior positioned T-loop suing. Neverthless, because of the small amount of the forces, the effect of vertical force was not significant.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2004.11a
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• pp.169-174
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• 2004

To design ship channel is one of important factors for planning and developing a port. In most case, the core factors for designing ship channel are the layout and width of dvnnel provided the net underkeel clearance is assessed as safety. In this study, Variable Bumper Area(VBA) model is applied to design and assess ship channel. This model reflects ship's principle dimension, ship domain theory, ship speed, conning officer's ship handling skill and experience and all external forces which cause leeway, set and drift and the change of ship maneuvering characteristics. Full Mission Ship Handling Simulator is used to analyze ship dynamic data according to conning officer's ship control, external forces, etc. This model uses Domain-index for assessing the efficiency and safety of the channel. The proposed model is applied to Ulsan new port plan which has a channel width of 1.5 times the length if the largest vessel, a radius if 5 times the length of the largest vessel in a curve of 57 degree centerline angle and SBM facility adjacent to the lateral edge if channel. The result of this study shows tint the width and radius of channel curve are suitable for the target ship but the difficulty of ship handling is caused by the large course change and SBM located in the vicinity if channel.

• Journal of the Institute of Convergence Signal Processing
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• v.21 no.4
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• pp.170-176
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• 2020

In this study, the lift, drag and moments of the rudder that influences on the maneuvering ships directly has been investigated using CFD(Computational Fluid Dynamics). One of typical ship rudders effecting on the forces and moments is the bow rudders during maneuvering on the sea. Thus, the forces and moments should be investigated for the bow of ship rudder. Among the IFS bow rudder series, the balance IFS 54 BR 15 is used for study. As a turbulent model, standard k-epsilon is applied to this study. The hydrodynamic of the bow rudder, especially lift, drag and moment coefficients are calculated for the different angles of attack. The angles of attack between water flow and rudder are presented in cases including 0°, 5°, 10°, 15°, 20°, 25°, 30° and 35°. The results of calculation for those influences on maneuvering performance of ships are compared with the relevant results of the previous experimental studies.

• The korean journal of orthodontics
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• v.31 no.1 s.84
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• pp.25-38
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• 2001

The purpose of this study was to compare the force, the displacement and the stress distribution on the maxillary first molars altered by the application of various asymmetric head-gear. For this study, the finite element models of unilateral Cl II maxillary dental arch was made. Also, the finite element models of asymmetric face-bow was made. Three types of asymmetric face-bow were made : each of the right side 15mm, 25mm and 35mm shorter than the left side. We compared the forces, the displacement and the distribution of stress that were generated by application of various asymmetric head-gear, The results were as follows. 1. The total forces that both maxillary first molars received were similar in all groups. But the forces that mesially positioned tooth received were increased as the length of the outer-bow shortened, and the forces that normally positioned tooth received were decreased as the length of the outer-bow shortened. 2. In lateral force comparison, the buccal forces that normally positioned tooth received were increased as the length of the outer-bow shortened, and the buccal fortes that mesially positioned tooth received were decreased as the length of the outer-bow shortened. Though the net lateral force moved to the buccal side of normally positioned tooth as the length of the outer-bow shortened, both maxillary first molars received the buccal force. That showed 'Avchiai Expansion Effect' 3. The distal forces, the extrusion forces and the magnitudes of the crown distal tipping that mesially positioned tooth received were increased as the length of the outer-bow shortened, and the forces that normally positioned tooth received were decreased as the length of the outer-bow was shortened. 4. The magnitude of the distal-in rotation that normally positioned tooth received were increased as the length of the outer-bow was shortened. But, mesially positioned tooth show two different results. For the outer-bow 15mm shortened, mesially positioned tooth showed the distal-in rotation, hut for the outer-bow 25mm and 35mn shortened, mesially positioned tooth showed the distal-out rotation. Thus, the turning point exists between 15mm and 25mm. 5. This study of the initial stress distribution of the periodontal ligament at slightly inferior of the furcation area revealed that the compressive stress in the distobuccal root of the normally positioned tooth moved from the palatal side to the distal side and the buccal side successively as the length of the outer-bow shortened. 6. This study of the initial stress distribution of the periodontal ligament at slightly inferior of the furcation area revealed that the magnitudes of stress were altered but the total stress distributions were not altered in the mesiobuccal root and the palatal root of normally positioned tooth, and also three roots of mesially positioned tooth as the length of the outer-bow shortened.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.23 no.5
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• pp.567-575
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• 2010

The mechanical properties of Carbon nanotube is superior such that it can be used in many areas of engineering field in the future, though the analysis of the mechanical behavior of nanotube is expensive due to its small size and uniqueness when the molecular dynamics or a generalized function theory is applied. To overcome these disadvantages, the force field between Carbon atoms can be substituted by structural members. In this study, main forces between atoms in Carbon nanotube are described by 0.1 nanometer length circular beams and linear behaviors under compression are investigated. The linear behavior is in good agreement with results by other methods. This method can be used in nonlinear analysis of nanotube when the beam elements are properly configured.