• Proceedings of the KSR Conference
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• 2005.11a
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• pp.842-847
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• 2005

In recent railroad markets, the use of steel sleepers is gradually increased due to various advantages in resistance for impact as well as economical efficiency for production, construction. maintenance and recycle. The typical steel sleepers which are successfully used in railroad markets are n-type of Corus Inc. in England and Y-type of ThyssenKrupp Gft Gleistechnik in Germany. Both types have merits and demerits in safety and economical efficiency. In 1990, n-type steel sleeper was developed in Korea, but was failed in putting into practical use, due to the subsidence into the ballast by Jive loads and welding crack, etc.. In this paper, in order to develop optimal shape of n-type steel sleepers for domestic rail mads, parametric studies for cross section, thickness, are performed.

• Journal of the Korean Society for Railway
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• v.13 no.2
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• pp.214-221
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• 2010

The transitional zone between tunnel and earthwork is one of the most vulnerable areas site for railway lines and because of differential settlement due to different stiffness of each supporting layer, it has to conducted a maintenance work constantly. In this study, it is conducted to compare the effect of reinforcement by wheel load and displacement of the sleepers after existing sleepers are replaced with the large sleepers for 20m long in-field transitional zone. Also, numerical parametric study using multi-layer elastic method has been performed to compare rail force, settlement and stresses of ballast while varying size and space of the sleeper. The field test and numerical results show that replacing the large sleepers improves about 10% of total settlement and coefficient of wheel force than conventional sleepers. Effectiveness of improvement is about 9.3%, 4%, 14.5% for rail seat force, settlement of sleepers and ballast pressure respectively with size of sleepers.

• The Journal of the Convergence on Culture Technology
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• v.6 no.3
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• pp.335-340
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• 2020

The purpose of this study was to compare the dynamic behavior of STEDEF track that of the sleeper floating track on urban rapid transit according to replacing the resilience pads and analyze the necessity of replacing the resilience pads experimentally. It was analyzed that the uniformity of the track support stiffness could be secured by replacing the used resilience pads with new resilience pads. Therefore, by replacing the used resilience pads, the measured track impact factor was found to be dramatically reduced below the track design standard, and it was analyzed that the track support stiffness could be restored to the design value. As a results, it is possible to restore track support stiffness to the design value and reduce track impact factor by replacing timely resilience pads, which is important to securing durability and improving service life of track components.

• Journal of the Korean Society of Hazard Mitigation
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• v.6 no.4 s.23
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• pp.1-6
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• 2006

In terms of the speed-up of the conventional line, the research for a improved turnout was carried out continually around world. A turnout is known that it is the most unstable equipment structurally in the rail system. So, the turnout is needed more stable structure. An accurate assembly of turnout affects traveling qualify of turnout area and running safety. Therefore, a turnout which is pre-assembled at a factory by using the split PC sleeper is transported to construction site recently in advanced countries. In this paper, the performance measurements which estimate the safety of the split PC sleepers which are adopted for the first time to improve performance of turnout are implemented indoors. The split PC sleeper is one of components of the improved turnout. The test is considered of the worst ballast condition under the maintenance work as like STT(Swithc Tie Tamper) or MTT(Multiple Tie Tamper). These experiments results indicate that structural safety for the expansion joint of the split PC sleepers.

• Journal of the Korean Society for Railway
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• v.13 no.6
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• pp.565-569
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• 2010

Sleepers perform bearing rails and are underneath rails. Therefore, the current and voltage of rails are related to the resistance of sleepers. In case that the resistance of sleepers are low, operation problems of relays in tr ack circuits are occur because of flowing leakage current through sleepers. So the condition that the track circuit is always occupied by a train is kept. Currently, the creosote has been used in wood sleepers due to prevention against putrefaction. After a long time, the material is changeable to the chemistry material bases on carbon dioxide or carbon. So, the insulation resistance of wood sleepers is lower than the initial insulation resistance. In case of effecting wood sleepers as conductors, amplitude of the current and voltage on rails is decreased. This phenomenon causes that a train does not receive signals. In this paper, four-network model on the track circuit including the insulation resistance of sleepers is suggested. Also, the standard value of the resistance in straight section is proposed in the wood sleeper.

• The Journal of the Convergence on Culture Technology
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• v.6 no.2
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• pp.461-466
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• 2020

In this study, the relationship between the track support stiffness and the track impact factor for a sleeper floating track and a turnout system with wood ties currently employed in Korean urban transit was assessed by performing field tests using actual vehicles running along the service lines. Field tests were performed on four track systems (i.e., sleeper floating track, and point, lead and crossing sections of turnout system). The theoretically designed track impact factor and track support stiffness were compared with the corresponding track impact factor and track support stiffness measured through field tests for the target tracks on the service line. The track impact factor for the service line appeared to increase with the deviation of track support stiffness according to vehicle driving direction; therefore, it was inferred that the deviation of track support stiffness between each track section directly affected the track impact factor.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.2
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• pp.145-152
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• 2010

This study investigates experimentally flexural behavior and CFB(Carbon Fiber Bar) reinforcing effects of timber sleeper in traditional storied tower house. As a test result, standard sleepers without CFB(Carbon Fiber Bar) reinforcement show flexural cracks at the bottom member at the beginning of loading stage and leads to fracture. However, reinforced specimens with CFB show initial shrinkage at the upper part of specimen by compression, instead of flexural cracks at the bottom, and finally show compressive failure or fracture after failure of CFB and it proves that reinforcing effects by CFB are exerted from early loading. Reinforced specimens showed higher strength in yield strength by 6%~38%, and ultimate strength by 8%~17%, than those of standard specimens. Reinforced specimen is considered that specimen with flexural reinforcement using CFB can expect flexural deflection control effect. Reinforced specimen shows higher ductile coefficient increase of average 141% compared than standard specimens and it proves that higher structural ductile behavior can be expected in reinforced specimens.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.14 no.1
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• pp.62-71
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• 2007

Purpose: This study was done to compare sleep patterns, factors of sleep disturbance and sleep enhancement behaviors between sleep disturbance and non-sleep disturbance elderly patients. Method: The participants were 117 patients over 65 years old who were hospitalized at 5 general hospitals in Seoul. There were 83 patients in the good sleeper group and 34 in the poor sleeper group. The survey questionnaires included questions on general characteristics, sleep patterns, sleep disturbing factors, and sleep enhancement behaviors of the patients. Results: For sleep patterns and environmental factors of sleep disturbance, the poor sleepers was significantly higher than that of the good sleepers. Significant differences between good sleepers and poor sleepers were also found on the following variables: Environmental factors of sleep disturbance -'Sound of other patient's or care-giver's', 'Discomfort of bed, linen, pillow and patient's gown', 'Light in the room', 'Emergency situations', 'Temperature of patients rooms too hot or too cold'. The significant physical factor of sleep disturbance was 'Hard to breath even without moving' and for sleep enhancement behaviors: 'Use of ear plugs or eye covers' Conclusion: Consequently it is necessary to develop positive and differentiated programs for sleep enhancement for the inactive and poor sleeper among the elderly patients.

• The Journal of the Convergence on Culture Technology
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• v.4 no.4
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• pp.413-418
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• 2018

The purpose of this study is to investigate the cause of rail corrugation and the track force for concrete track (STEDEF) in the urban transit. From the field measurements, the dynamic wheel load, vertical displacement of sleeper and rail bending stress were measured and it was evaluated by regarding to the rail corrugation. As a result of the study, the causes of rail corrugation was experimentally proved by frequency analysis using measured dynamic wheel load data. The influence of corrugation on dynamic wheel load, rail bending stress and sleeper displacement was evaluated that the periodic irregularities of rail corrugation on the rail surface amplified the dynamic track force such as the dynamic wheel load, and thus the rail bending stress and the vertical displacement of sleeper could be increased by a maximum of 1.7 times.

• Physical Therapy Korea
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• v.30 no.1
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• pp.59-67
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• 2023

Background: Posterior capsule tightness (PCT), commonly seen in overhead athletes, is a soft tissue adaptation that is also noted in non-throwers. PCT is associated with scapular and humeral kinematic alterations, significant restriction of shoulder internal rotation (IR) range of motion (ROM), and significant scapular anterior tilting. Sleeper and cross-body stretches (CBS) are suggested for PCT and IR deficits, and have been modified since introduction. A novel modified sleeper stretch (NMSS) was designed in this study to prevent the risk of anterior translation of the humeral head. Though the effects of posterior shoulder stretching exercise have been widely studies, to the best of our knowledge, no previous studies have investigated the effectiveness of posterior shoulder exercises in decreasing scapular anterior tilting. Objects: To compare the immediate effects of two posterior shoulder stretching exercises (NMSS and CBS) on scapular anterior tilting and shoulder IR ROM. Methods: Thirty-two subjects with anteriorly tilted scapula and IR deficits [mean age: 24.3 ± 2.5 years; 15 males and 17 females] participated in this study. Subjects were randomly assigned to either the NMSS or CBS groups. Scapular anterior tilting (at rest and at shoulder 60° active IR) and shoulder IR ROM were measured before and immediately after intervention. Results: Scapular anterior tilting significantly decreased, while the shoulder IR ROM significantly increased in both groups. However, there was no significant group-by-time interaction effect or significant difference between the groups. Conclusion: Both stretching exercises were effective in restoring shoulder IR ROM and decreasing scapular anterior tilting.