• Proceedings of the Korean Geotechical Society Conference
• /
• 2005.03a
• /
• pp.1572-1579
• /
• 2005

New procedure for evaluation of creep reduction factor using performance limit strain concept was introduced and confirmed through the creep test results. To determine the performance limit strain of the textile geogrid used in this study, the Sherby-Dorm Plots were applied and the results were compared with the results that applied existed limit strain criteria (GRI test method GG-4). The limit creep strain of the geogrid samples that determined by using the Sherby-Dorm Plots were all 11%. This value is more higher than the existed criteria as 10%. From this 11% limit strain the creep reduction factors were calculated at 100,000 hours design. It was resulted in 1.45 for all of the geogrid samples(8t/m, 10t/m). Finally, when it was compared with the creep reduction factors that using 10% criteria, there were some decrease of reduction factor values about $0.06{\sim}0.14$.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2008.10a
• /
• pp.196-203
• /
• 2008

Durability of geosynthetics for soil reinforcement is accounted for creep and creep rupture, installation damage and weathering, chemical and biological degradation. Among these, the long-term creep properties have been considered as the most important factors which are directly related to the failure of geosynthetic-reinforced soil(GRS). However, the creep test methods and strain limits are too various to compare the test results with each other. The most widely used test methods are conventional creep test, time-temperature superposition and stepped isothermal method as accelerated creep tests. Recently developed design guidelines recommend that creep-rupture curve be used to determine the creep reduction factor($RF_{CR}$) which is a conservative approach. In this study, the different creep test methods were compared and the creep reduction factors were estimated at different creep strain limits of 10% of total creep strain and creep rupture. In order to minimize the impact of creep strain to the GRS structures, the various creep reduction factors using different creep test methods should be investigated and then the most appropriated one should be selected for incorporating into the design.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.28 no.3
• /
• pp.607-612
• /
• 1999

Cigarette smoking is the potential risk factor for lung cancer and chronic pulmonary disease, as well as inflammatory bowel disease and reproductive malfunction. Nicotine and tar have been im plicated as a major factor in the pathogenesis of the diseases. Nicotine increases heart rate and blood pressure due to stimulation sympathetic neurotransmission and tar also accounts for the severe damage of peridontal diseases and osteoporosis in postmenopausal women. Portulaca oleracea, which contains significant amount of K+, noradrenaline and dopamine as well as various nutrients, has been used for many medicinal purposes and one of which is the detoxification of insect or snake toxins. The purpose of this study was to investigate the action of Portulaca oleracea extracts on the reduction of harmful materials of tabacco. The reduction percentages were measured in the presence and absence of each solvent extract of Portulaca oleracea using reversed C18 column of HPLC. Nicotine reduction effects were obtained from aqueous, methanol and chloroform extracts of Portulaca oleracea as 89%, 55% and 51%, respectively. The results suggest that the polar extracts of Portulaca oleracea affects the reduction of nicotine which is responsible for many diseases.

• Tunnel and Underground Space
• /
• v.29 no.5
• /
• pp.346-355
• /
• 2019

When evaluating pillar stability in very closely spaced tunnels, a local safety factor (strength/stress ratio) at the minimum width has been widely used. Tension bolts have been frequently applied as reinforcement for the cases where safety factors are less than 1.0 from FEM stress analysis. However, the local safety factor shows a constant value irrespective of the change in pillar width/tunnel diameter (PW/D) and the safety factor of the pillar is underestimated because the variation of deviation stress is relatively small even when the pre-stressing is applied to the tension bolt. In addition, the average safety factor proposed by Hoek and Brown(1980) was reviewed, but the pillar safety factor was relatively overestimated when the width of the pillar was increased. As an alternative, the SRM safety factor using shear strength reduction method shows the effect of changing the safety factor in the case of no reinforcement and tension bolt reinforcement as the pillar width/tunnel diameter(PW/D) changes. The failure shape is also similar to the previous limit theory result. In this study, the safety factor was evaluated without considering rock bolt and shotcrete to distinguish reinforcing effect of tension bolt.

• Proceedings of the Korean Fiber Society Conference
• /
• 2003.10a
• /
• pp.104-104
• /
• 2003

Geosynthetic Reinforcements - membrane drawn type, warp/knitted type, junction bonded type and composite type geogrids, strip type reinforcement - were used to compare the long-term perfor-mance by total factor of safety with reduction factors during service periods. To evaluate the reduction factors, wide-width tensile property, installation damage, creep deformation, chemical and biological degradation tests were performed. Long-term design strengths of geosynthetic reinforcements were calculated by using GRI standard Test Method GG4.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2004.11a
• /
• pp.1020-1023
• /
• 2004

Recently, Cooling tower are used the necessary element in a residential area and living space on the viewpoint of indoor temperature control. The purpose of this study is to assistance the comfortable environment and economical measures of noise transmission mechanism on tile cooling tower. The results show that noise evaluation interact the main factor of distance reduction and diffraction reduction. Noise criterion apply to the NC level and equivalent transmission loss about already the design of noise reduction.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2011.06a
• /
• pp.1299-1300
• /
• 2011

• Structural Engineering and Mechanics
• /
• v.41 no.3
• /
• pp.365-378
• /
• 2012

In this study, strength reduction factors are investigated for SDOF systems with period range of 0.1-3.0 s with elastoplastic behavior considering soil structure interaction for 64 different earthquake motions recorded on different site conditions such as rock, stiff soil, soft soil and very soft soil. Soil structure interacting systems are modeled and analyzed with effective period, effective damping and effective ductility values differing from fixed-base case. For inelastic time history analyses, Newmark method for step by step time integration was adapted in an in-house computer program. Results are compared with those calculated for fixed-base case. A new equation is proposed for strength reduction factor of interacting system as a function of structural period of system (T), ductility ratio (${\mu}$) and period lengthening ratio (T/T). It is concluded that soil structure interaction reduces the strength reduction factors for soft soils, therefore, using the fixed-base strength reduction factors for interacting systems lead to non-conservative design forces.

• Journal of Digital Convergence
• /
• v.10 no.11
• /
• pp.493-502
• /
• 2012

This study aimed to determine the management and environmental factors affecting medical expense reduction. For analysis, medical expenses were divided into hospitalization expenses and outpatient treatment expenses, and the rate of medical expense reduction was classified into initial and final reduction rates. Data were collected through a direct survey among 205 directors of independent health insurance review departments of hospital-level medical institutions in Korea. The results of the study are discussed below: In the analysis, differences in the initial and final reduction rates of hospitalization expenses and outpatient treatment expenses were compared. The results showed that, in hospitalization expenses, the initial and final reduction rates were both significantly affected by the following management factors: number of beds, number of departments, number of personnel reviewing health insurance cases, and total number of employees. Further, in outpatient treatment expenses, the initial and final reduction rates were both affected significantly by the following management factors: management of medical records, number of beds, number of departments, number of personnel reviewing health insurance, and total number of employees. The management factors significantly affecting both the initial and final reduction rates were higher number of beds for hospitalization expenses and electronic medical record management for outpatient treatment expenses. The environmental factors significantly affecting both the initial and final reduction rates of hospitalization expenses were a highly cooperative work environment, better implementation of indicator management systems, and overtime pay. Better implementation of indicator management system and a committee for handling medical expenses had significant effects on the initial reduction rate for outpatient treatment expenses. A highly cooperative work environment, better implementation of indicator management system, and overtime pay had significant effects on the final reduction rate for outpatient treatment expenses.

• Journal of the Korean Chemical Society
• /
• v.24 no.2
• /
• pp.91-100
• /
• 1980

A formula for calculation of the magnetic moments for octahedral $[Ti(III)A_3B_3]$ type complexes with axial symmetry has been developed and the magnetic moments for these complexes are calculated, using the experimental values of the distortion parameters$({\delta})$, spin-orbit coupling constants and orbital reduction factors. The calculated magnetic moments for axially distorted octahedral $[Ti(III)A_3B_3]$ type complexes are in resonable agreement with the experimental valuest It is found that the calculated magnetic moments decrease as the extent of axial distortion increases and the orbital reduction factor decreases. A calculation method of the magnetic moments for octahedral $[Ti(III)A_3B_3]$ type complexes which are in a ligand field of lower than axial symmetry has also been developed and the structure of distorted octahedral $[Ti(III)A_3B_3]$ type complexes are discussed on the basis of the of the calculated magnetic moments.