• Journal of Physiology & Pathology in Korean Medicine
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• v.21 no.1
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• pp.126-135
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• 2007

This study was conducted to identify the effects of the oriental medicine Qigong Exercise on the brain power, HRV, pulsation, live blood condition among young boys and girls. The study was performed with two group(control group and experimental group) in a pre-test/post-test design. The subjects were 44 young boys and girls selected by a some middle school in Busan. The oriental medicine Qigong Exercise program consists of 80-minute sessions three times a week over 5 months. All of the subjects were examined on the congnition assessment tool, stress assessment tool, oriental medicine pulsation 3-D MAC, live blood condition analyzer Prior and post surveys were measured before and after the experiment. In the cognition assessment, the amplitude of ERS were increased afer Qigong Exercise. The Success and the Concentration were significantly increased afer Qigong Exercise, the Error was significantly decreased afer Qigong Exercise. The Cognition strength was significantly increased, but the Reponse time was not significantly decreased afer Qigong Exercise. And the Workload was not significantly decreased, the Total Score was not significantly increased afer Qigong Exercise. Among the stress assessment, RRV tachogram's ‘mean RR’ was significantly increased, ‘mean HRV’ was significantly decreased afer Qigong Exercise. SDNN was not significantly increased, Complexity was not significantly increased afer Qigong Exercise. And TP(RRV power's total power) was not significantly increased, VLF and HF was significantly increased, and LF was significantly decreased afer Qigong Exercise. ANS's norm LF was not significantly decreased, but norm HF was significantly increased afer Qigong Exercise. In the RRV's Phase Plot, RMSSD and SDSD were not significantly increased, pnn50 was not significantly decreased afer Qigong Exercise. On the whole, Parasympathetic Activity and Stress Endurance were significantly increased, but Cardiac Activity and Physical Arousal were not significantly increased afer Qigong Exercise. Cardiac Aging was not significantly decreased afer Qigong Exercise. Sympathetic Activity, Autonomic Nervous System Balance and Heart-load were not significantly decreased afer Qigong Exercise. In the pulsation, press power was increased(15%), and w/t(pressurization time / pulsation time) was decreased(20%) afer Oigong Exercise. And the live blood condition was not changed afer Qigong Exercise. As mentioned above; the oriental medicine Qigong Exercise program was identified the effects of the inspiration of the brain power, heart rate and anti-stress.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.1
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• pp.339-346
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• 2019

Various studies have been conducted to evaluate the probabilistic fatigue life of steel railway bridges, but many of them are based on a relatively simple model of crack propagation. The model assumes zero minimum stress and constant loading amplitude, which is not appropriate for the fatigue life evaluation of railway bridges. Thus, this study proposes a new probabilistic method employing an advanced crack propagation model that considers the live-dead load ratio for the fatigue life evaluation of steel railway bridges. In addition, by using the rainflow cycle counting algorithm, it can handle variable-amplitude loading, which is the most common loading pattern for railway bridges. To demonstrate the proposed method, it was applied to a numerical example of a steel railway bridge, and the fatigue lives of the major components and structural system were estimated. Furthermore, the effects of various ratios of live-dead loads on bridge fatigue life were examined through a parametric study. As a result, with the increasing live-dead stress ratio from 0 to 5/6, the fatigue lives can be reduced by approximately 30 years at both the component and system levels.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.4
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• pp.37-44
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• 2019

The purpose of this study is to rationally determine the priority of seismic reinforcement of main(key) members of bridges. Cable Supported bridge was selected as the evaluation target and the reliability based on the probability distribution was used to evaluate the seismic fragility of the key members as a quantitative indicator. The safety factor, which is a random variable, is considered an artificial (fixed load and live load) load and a natural (earthquake, wind, temperature, etc.) load. The seismic load is applied as a possible earthquake during the lifetime of the bridge. From analyzing the fragility of each key member based on the seismic reliability, it can be concluded that the shoe (23.8%) was the most fragile, where the other members are ranked as place concrete (20.5%), pier (18.9%), foundation (17.3%) and cable (5.0%) respectively.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.3
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• pp.189-195
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• 2017

The only method used in the power stations in order to deliver generated electric power is 6 kV XLPE (or CV) single core cables. Among many kinds of accidents happening in the power stations, the outbreak of fire due to the deterioration of live cables causes enormous socioeconomic losses. From the installation of the cables, the management and diagnose should be thoroughly made. Even though it differs depending on the installations and usage conditions, the cross-sectional area of cables is in shortage. The excessive allowable temperature caused from the current causes the deterioration of cables. In order to prevent an unexpected breakdown of live cables, we have invented a device to monitor and diagnose the status of cables. We have installed our device in the Korea Western Power Co., Ltd.. In this paper, we present our research results in situ that we have obtained by measuring the temperature of sheath, changing with the surrounding circumstances, especially ambient temperatures. We also show our study results of characteristics for temperature of sheath surface and load current at the ambient temperatures of $40^{\circ}C-10^{\circ}C$.

• Journal of the Korea Concrete Institute
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• v.19 no.6
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• pp.755-762
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• 2007

For the evaluation of the load carrying capacity of the deteriorated PSC I girder bridge in service load state and the verification of the grade to the reinforcement effect of actual bridge strengthened by external prestressing tendons, the field test using vehicles is applied widely. Because this teat was executed in elastic range, the investigation of the characteristics of behavior caused by live load is only available. And it is impossible to estimate load carrying capacity in limit state and nonlinear behavior after that a crack is appeared. In this study, the 27-year-old prestressed concrete girder bridge is used and various load tests are performed, so we evaluate the behavior characteristics of the bridge in service load state and ultimate load state, and estimate the load carrying capacity of bridge. In addition, the artificial damages are induced from cutting internal tendons, and external tendons is added to strengthen it as much as vanished internal tendons. Next we compare the damage state with the strengthening state. In case of the application of external prestressing method to PSC I girder bridge, the present experiment result may decide more exactly the load carrying capacity of actual bridge, the amount for reinforcement, and the standard of quality control etc. at reinforcement work.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.6
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• pp.81-88
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• 2008

The purpose of this study is to improve and modify the evaluation method of load carrying capacity for simply supported PSC I Typed girder bridge. To do this, conventional ASD(Allowable Stress Design) and USD(Ultimate Strength Design) evaluation method were initially investigated and it was evaluated that the conventional USD evaluation method may perform the load carrying capacity as conservative because it do not consider the prestressing upper-force effect of simply supported PSC I Typed girder bridge. To reasonably evaluate the load carrying capacity, the upper-force effect should be considered to the PSC I Typed girder bridge. Thus, in this study, the MUSD method was Suggested and compared to the nonlinear FEM based-load carrying capacity using the live load factor and the efficiency of the evaluation method of load carrying capacity was investigated by experimental and analytical result. In the result of this study, the suggested MUSD evaluation method showed a reasonable evaluating result for the simply supported PSC bridge. For the new technique of load carrying capacity based on the nonlinear FEM analysis, it could effectively simulate the load-deflection relationship and the load carrying capacity of the PSC I Typed girder bridge.

• Journal of the Korean Society for Railway
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• v.13 no.2
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• pp.186-193
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• 2010

Track system and periodic live load are characteristics of railway bridges. In the design and construction of railway bridge, periodic live load increases the importance of dynamic behavior. And It is well known that behavior of railway bridge may be affected by track system in real bridge. Through experimental study, static and dynamic behaviors were investigated. Deflection and stress due to bending moment were measured, the location of neutral axis of each section, natural frequency, damping ratio were analyzed for each three track systems - girder only, installed ballast track system and installed concrete slab track system. According to measured values for the each type of track system, concrete track system increases the stiffness of bridge by 50%, and ballast system does by 7%, dynamic responses of structure change linearly with the magnitude of load and location of neutral axis of each sections varies with each track system. Damping ratio is almost equal without and with track. Therefore, the effects of track system on the integral behaviors of railway bridge can not be ignored in the design of bridge, especially in the case of concrete slab track system. So study of the quantitative analysis method for effects of track system must be performed.

• Structural Monitoring and Maintenance
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• v.9 no.4
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• pp.323-336
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• 2022

Steel truss bridge is one of the most widely used bridge types in Indonesia. Out of all Indonesia's national roads, the number of steel truss bridges reaches 12% of the total 17,160 bridges. The application of steel truss bridges is relatively high considering this type of bridge provides advantages in the standardization of design and fabrication of structural elements for typical bridge spans, as well as ease of mobilization. Directorate of Road and Bridge Engineering, Ministry of Works and Housing, has issued a standard design for steel truss bridges commonly used in Indonesia, which is designed against the design load in SNI 1725-2016 Bridge Loading Standards. Along with the development of actual traffic load measurement technology using Bridge Weigh-in-Motion (B-WIM), traffic loading data can be utilized to evaluate the reliability of standard bridges, such as standard steel truss bridges which are commonly used in Indonesia. The result of the B-WIM measurement on the Central Java Pantura National Road, Batang - Kendal undertaken in 2018, which supports the heaviest load and traffic conditions on the national road, is used in this study. In this study, simulation of a sequences of traffic was carried out based on B-WIM data as a moving load on the Australian type Steel Truss Bridge (i.e., Rangka Baja Australia -RBA) structure model with 60 m class A span. The reliability evaluation was then carried out by calculating the reliability index or the probability of structural failure. Based on the analysis conducted in this study, it was found that the reliability index of the 60 m class Aspan for RBA bridge is 3.04 or the probability of structural failure is 1.18 × 10^-3, which describes the level of reliability of the RBA bridge structure due to the loads from B-WIM measurement in Indonesia. For this RBA Bridge 60 m span class A, it was found that the calibrated nominal live load that met the target reliability is increased by 13% than stated in the code, so the uniform distributed load will be 7.60 kN/m² and the axle line equivalent load will be 55.15 kN/m.

• Journal of the Korean Geotechnical Society
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• v.26 no.7
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• pp.17-24
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• 2010

Load Resistance Factor Design method is used increasingly in geotechnical design world widely and resistance factors for drilled shafts are suggested by AASHTO. However, these resistance factors are determined for intact rock conditions; by comparison, most of bedrocks in Korea have weathered condition, so that applying the AASHTO resistance factors is not reasonable. Thus, this study suggests the proper resistance factors for design of drilled shaft in Korea. The 22 cases of pile load test data from 8 sites were chosen and reliability-based approach is used to analyze the data. Reliability analysis was performed by First Order Second Moment Method (FOSM) applying 4 bearing capacity equations. As a result, when the Factor of Safety (FOS) was selected as 3.0, the target reliability indexes (${\beta}_c$) were evaluated as 2.01~2.30. Resistance factors and load factors are determined from optimization based on above results. The resistance factors ranged between 0.48 and 0.56 and load factors for dead load and live load are evaluated as approximately 1.25 and 1.75 respectively. However, when the target reliabilities are considered as 3.0, the resistance factors are evaluated as approximately 50% of the results when the target reliability index was 2.0.

• Journal of Korean Society of Steel Construction
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• v.17 no.5 s.78
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• pp.527-536
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• 2005

A method of reinforcement using external tendons has been found to be one of the effective techniques of reinforcement and its application is increasing. In this paper, the method to calculate the initial tendon force is proposed for the improvement of load-carrying capacity in existing steel-concrete composite bridges. An equation for the increment of tendon force was derived for tendon configurations and live load types, and the effect of reinforcement in a composite beam was numerically studied. The method to calculate the number of tendon and initial tendon force was presented by proposing the new method to calculate the rating factor, which considers the increment of tendon force. The method was shown to be effective for an existing steel-concrete bridge.