• Journal of Korean Society of Steel Construction
• /
• v.25 no.3
• /
• pp.243-254
• /
• 2013

Internally Confined Hollow RC(ICH RC) column consisted of concrete, transverse reinforcement, longitudinal reinforcement, and inner tube. It had good strength and ductility by core concrete was become triaxial confining state with transverse reinforcement and inner tube. There were two confining stress as external confining stress and internal confining stress in an ICH RC column. While external confining stress was researched by former researchers, internal confining stress has not researched. In this paper, confining stress of both Hollow RC column and ICH RC column was investigated using FEA program. Relation between theoretical confining stress and internal confining stress was drawn by analysis results. Modified failure condition equations of inner tube were suggested to base on failure condition equations of inner tube by former researcher. When thickness of inner tube was calculated by modified equations, it could be economic because thickness of inner tube was reduced 50% compared with former researcher equations in order to same confining stress.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2008.04a
• /
• pp.301-304
• /
• 2008

The stair joints constructed with prefabricated system are general method doing structure design at hinge. If you regarded joints to come in contact with a flight of stairs and a slope of stairs as hinge, the moment performance of joints is not in the least moment, so as the bending moment of the stair case is increased, the reinforcement increase. Also the use is decreased because increasing the joint damage of the vibration & fatigue load. No less the reason constructed with pin the stair joints because the construction efficiency of field work is useable. Recently, they are considering the construction efficiency, while the semi-rigid detail for bending performance of joints is proposed, but for now they don't reflect the detail. Therefore, we proposed that reflecting the method at design semi-rigid joints. We compared the moment performance with the stair joints designed at the rigid joints, semi-rigid joints and pin joints. The nonlinear behavior of staircase core statically indeterminate structure. The result of research is that a bending stiffness modulus bring to reflect the semi-rigid performance, the performance of the semi-rigid joint is better than pin joints, and that is judged the system better seismic and vibration performance because have excellent ductility more than rigid joint.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.19 no.5
• /
• pp.749-760
• /
• 2017

Recently, the proportion of tunnel structures in roads and railways has increased rapidly. Along with this trend, the rate of occurrence of cracks and dropouts in concrete lining of tunnel structures is increasing. Generally, maintenance of such concrete lining is normalized and managed as the core of maintenance work in tunnel maintenance. However, the maintenance of the tunnel pavement is important in securing driver in the tunnel. In the design of tunnels, the underground condition of the tunnel is designed to be in good rock condition, so there have not been many cases of cracks in the tunnel pavement in the past. Recently, the construction of tunnel structures has been rapidly increased, and the length of the tunnels has become longer.Tunnel pavement installed in these ground conditions is increasing the occurrence of cracks in the pavement due to decrease of bearing capacity of the pavement after a long time. In this study, FWD and GPR were conducted to analyze the types of cracks and the reduction of bearing capacity in the tunnel.

• Journal of Radiation Protection and Research
• /
• v.28 no.2
• /
• pp.109-116
• /
• 2003

Based on the necessity to evaluate the activation products inventory during decommissioning lot domestic nuclear power plants, a preliminary estimation of the activation products inventory for Kori unit 1, which is getting close to the end of lifetime, was carried out with ANISN and ORIGEN2 code. In order to calculate neutron nux using ANISN code, the reactor was divided into 9 zones from core to bioshield concrete for radial direction. Also :he cross-section of main nuclides were calibrated with neutron flux in the reactor pressure vessel(RPV) region. The results showed that 95 % of tile total radioactivity in RPV from reactor shutdown to 10 years came from the nuclides of $^{55}Fe,\;^{59}Ni,\;^{63}Ni\;and\;^{60}Co$. And the total radioactivity with cooling of more than 50 years after decommissioning was no more than 0.2 % of at the time of shutdown. Considering the weight of RPV is 210 tons, the total radioactivity of RPV reached to $5.25{\times}10^{6}GBq$ at shutdown time. As compared with the total radioactivity of bioshield concrete at reactor shutdown time, the radioactivity after tooling more than 10 years was below 1 %.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.28 no.3C
• /
• pp.149-158
• /
• 2008

This study is concerned with the characteristics of the behavior of drilled shafts with steel casing, a material that is used for large bridge foundations in Korea, and especially for weak submerged ground conditions. The effect of steel casing on bearing capacity of drilled shafts was also verified in this study. Three large drilled shafts with 1.8, 2.4, 3.0m diameter respectively were selected, and 3-D finite element analysis has been undertaken on the following three models: 1) drilled shafts without steel casing, 2) drilled shafts with steel casing, 3) steel-concrete composite drilled shafts. Interface element between concrete core and steel casing was taken into account, and ground conditions and load combinations were applied which had been considered in the fields. Detailed characteristics of the stress and displacement distributions were evaluated to understand the characteristics of the behavior of the drilled shafts. Based on the study performed, the steel casing used as load-carrying materials in the drilled shafts can reduce the horizontal and vertical displacement of drilled shafts by 32~37% and 15~19% respectively compared with drilled shafts without steel casing.

• Particle and aerosol research
• /
• v.13 no.1
• /
• pp.1-10
• /
• 2017

Accurate prediction of size, shape and velocity of a bubble rising through a liquid pool is very important for predicting the particulate removal efficiency in pool scrubbing, for designing engineering safety features to prepare for severe accidents in nuclear power plants, and for predicting the emission of fission products from MCCI (molten core-concrete interaction) process during severe accidents. In this review article, previous studies on the determination of the size, shape and rising velocity of a bubble in liquid are reviewed. Various theoretical and parameterization formulas calculating the bubble size, shape and velocity from physical properties of liquid and gas flowrate are compared. Recent studies tend to suggest simple parameterizations that can easily determine the bubble shape and rising velocity without iteration, whereas iteration has to be performed to determine the bubble shape and velocity in old theories. The recent parameterizations show good agreement with measured data obtained from experiments conducted using different liquid materials with very diverse physical properties, proving themselves to be very useful tools for researchers in related fields.

• Journal of Korea Association of Health Promotion
• /
• v.4 no.1
• /
• pp.28-38
• /
• 2006

Background : Phentermine classified by "sympathomimmetic amie", is a stimulant of sympatheic tone But there has been no concrete study which presents the influence of phentermine on autonomic nervous system. Analysis of Heart rate variability is reliable, non-invasive and very useful for evaluating function of autonomic nervous system. We tried to elucidate the influence of phentermine on autonomic nervovs system by heart rate variability. MethodsAmong the 70 candidates who participated in the double-blind case control study whichwas designed in purpose of approving whether- Adipekⓓ is effective for treatment of obesity, 45persons were folled up. From April, 2005 to May 2005, HRV of the candidates who takes phentermine or placebo for 1month, was recorded using BFM-5000ⓓ(medi-core) for 5 minutes in resting state. HRV measures were assessed by time-domain and by frequency- domain analysis. Time domain parameters contain SDNN(Standard Deviation of NN intervals) and RMSSD(Root-Mean-Square of Successive Differences), etc and frequency domain Parameters contain Total Power(TP), Low frequency(LF'0.04-0.15Hz) power. High Frequency(HF:0.15-0.4Hz) power and LF/HF ratio etc. Results: Intakes of phentermine reduce HRV significant1y. SDNN & RMSSD, the main tine domain parameters of HRV, were decreased significantly(P=0.007. 0.016). PSI(Physical Stress Index of Pressure Index) was increase significantly(P=0.002)The main frequency domain parameters(TP, LF & VLF), also decreased significantly. (P=0.024,0.033, 0.015)Conclusion: The result showed that intakes of phentermine reduce heart rate variability and influence on most parameters of HRV. So phentermine not only accelerates sympathetic tone, but also inhibit the balance and function of autonomic nervous system.

• Proceedings of the Korean Institute Of Construction Engineering and Management
• /
• 2008.11a
• /
• pp.918-921
• /
• 2008

There are various accident at the Construction site like fall, electric shock, roll over, clash, fire, body cutting. By the way, falls are the most causes accidents. So, the best way of decreasing Construction accidents is decreasing falls. Already, there are many studies about falls accidents, but those studies were pointed out unrealistic because falls accidents are increasing. For that reason, this study look for more concrete device. In this study, grasp the cause of falls accident from 2007 to 2008. 06. 30. And then, stand on this factor I set my face to look for the causes of falls accident. This access means will drive to remove core causes, and then that means will decrease the falls accidents. Moreover that means will contribute decreasing the hole construction accidents.

• Journal of Korea Water Resources Association
• /
• v.33 no.2
• /
• pp.237-245
• /
• 2000

Sihwa seadike is originally designed to control the water level In lake Sihwa. However the sluice gate is being operated everyday to preserve the water quality of lake. Due to the frequent operation of gates the bottom of drainage canal which is composed of weathered rock and soft rock is being scoured. Recently the bottom in the front area of apron was protected by putting underwater concrete. This study is carried out to understand the hydraulic situation for protection, and to estimate the trend of scouring by comparing between energy dissipation and registance of bottom rock. Annandale(1995) introduced the erodibility index theory, and suggested a criteria to judge the erodibility of rock through the relation between the erodibility index and energy dissipation. Determenation of erodibility index of rock is based on the results of sample core analysis, and the energy dissipation of flow is calculated from the estimation of total head on the scale model. These two values are plotted on the criteria, and the erodibility of rock is determined.

• Computers and Concrete
• /
• v.19 no.1
• /
• pp.7-17
• /
• 2017

In Chinese Design Codes, for super high-rise buildings with complex structural distribution, which are regarded as code-exceeding buildings, elasto-plastic time history analysis is needed to validate the requirement of "no collapse under rare earthquake". In this paper, a 117-story super high-rise building is discussed. It has a height of 597 m and a height-width ratio of 9.5, which have both exceeded the limitations stipulated by the Chinese Design Codes. Mega columns adopted in this structure have cross section area of about $45m^2$ at the bottom, which is infrequent in practical projects. NosaCAD and Perform-3D, both widely used in nonlinear analyses, were chosen in this study, with which two model were established and analyzed, respectively. Elasto-plastic time history analysis was conducted to look into its seismic behavior, emphasizing on the stress state and deformation abilities under intensive seismic excitation.From the comparisons on the results under rare earthquake obtained from NosaCAD and Perform-3D, the overall responses such as roof displacement, inter story drift, base shear and damage pattern of the whole structure from each software show agreement to an extent. Besides, the deformation of the structure is below the limitation of the Chinese Codes, the time sequence and distribution of damages on core tubes are reasonable, and can dissipate certain inputted energy, which indicates that the structure can meet the requirement of "no collapse under rare earthquake".