• Earthquakes and Structures
• /
• v.12 no.3
• /
• pp.349-357
• /
• 2017

The design of reinforced concrete structures strongly depends on the value of the compression concrete strength used for the structural components. Given the uncertainties involved on the materials quality provided by concrete manufacturers, in the construction stage, these components may be either over or under-reinforced respect to the nominal condition. If the structure is under reinforced, and the deficit on safety level is not as large to require the structure demolition, someone should assume the consequences, and pay for the under standard condition by means of a penalty. If the structure is over reinforced, and other failure modes are not induced, the builder may receive a bonus, as a consequence of the higher, although unrequested, building resistance. The change on the building safety level is even more critical when the structure is under a seismic environment. In this research, a reliability-based criteria, including the consideration of expected losses, is proposed for bonification/penalization, when there are moderated differences between the supplied and specified reinforced concrete strength for the buildings. The formulation is applied to two hypothetical, with regular structural type, 3 and 10 levels reinforced concrete buildings, located on the soft soil zone of Mexico City. They were designed under the current Mexican code regulations, and their responses for typical spectral pseudoaccelerations, combined with their respective occurrence probabilities, are used to calculate the building failure probability. The results are aimed at providing objective basis to start a negotiation towards a satisfactory agreement between the involved parts. The main contribution resides on the explicit consideration of potential losses, including the building and contents losses and the business interruption due to the reconstruction period.

• Physical Therapy Rehabilitation Science
• /
• v.6 no.4
• /
• pp.196-201
• /
• 2017

Objective: Musculoskeletal neck pain have many symptoms which include decreased range of motion (ROM) and muscle strength, and increased pain. However, the management methods are controversial. The purpose of this study was to examine the effects of three interventions on ROM, strength, and pressure pain threshold (PPT) with musculoskeletal neck pain. Design: Pretest-posttest design. Methods: Thirty subjects participated in this experiment. They were randomly assigned to thefollowing groups: passive stretching (PS) group (n=10), massage (MASS) group (n=10), and muscle energy technique (MET) group (n=10). The treatment were applied bilaterally on the upper trapezius. The PS was applied 3 times for 30 seconds each time. The MASS was applied using two different techniques for 2 minutes per technique. For MET, the subjects performed 2 sets of 3 repetitions of isometric resistance exercise that was maintained for 10 seconds, followed by 10 seconds of rest. ROM, strength, and PPT parameters were measured after intervention. Results: In the MASS group, there was a significant improvement in all outcomes except for muscle strength (p<0.05). In the MET group, ROM and strength significantly improved compared to the pre-treatment results (p<0.05). As result of measuring the amount of change in each group, there was a significant difference in ROM (flexion) in the PS group compared with the MASS and MET group, a significant difference in strength in the MET group compared with the PS and MASS groups, and a significant difference in PPT in the MASS groups compared with the PS and MET groups (p<0.05). Conclusions: This study showed that PS, MASS, and MET are effective methods for improving ROM, strength, and PPT for musculoskeletal neck pain. Therefore, various therapeutic interventions for improving ROM, strength, and pain are suggested.

• Advances in concrete construction
• /
• v.6 no.4
• /
• pp.345-362
• /
• 2018

In this paper, mechanical and short-term durability properties of fly ash and slag based geopolymer concretes (FAGPC-SGPC) were investigated. The alkaline solution was prepared with a mixture of sodium silicate solution ($Na_2SiO_3$) and sodium hydroxide solution (NaOH) for geopolymer concretes. Ordinary Portland Cement (OPC) concrete was also produced for comparison. Main objective of the study was to examine the usability of geopolymer concretes instead of the ordinary Portland cement concrete for structural use. In addition to this, this study was aimed to make a contribution to standardization process of the geopolymer concretes in the construction industry. For this purpose; SGPC, FAGPC and OPC specimens were exposed to sulfuric acid ($H_2SO_4$), magnesium sulfate ($MgSO_4$) and sea water (NaCl) solutions with concentrations of 5%, 5% and 3.5%, respectively. Visual inspection and weight change of the specimens were evaluated in terms of durability aspects. For the mechanical aspects; compression, splitting tensile and flexural strength tests were conducted before and after the chemical attacks to investigate the residual mechanical strengths of geopolymer concretes under chemical attacks. Results indicated that SGPC (100% slag) is stronger and durable than the FAGPC due to more stable and strong cross-linked alumina-silicate polymer structure. In addition, FAGPC specimens (100% fly ash) showed better durability resistance than the OPC specimens. However, FAGPC specimens (100% fly ash) demonstrated lower mechanical performance as compared to OPC specimens due to low reactivity of fly ash particles, low amount of calcium and more porous structure. Among the chemical environments, sulfuric acid ($H_2SO_4$) was most dangerous environment for all concrete types.

• Transactions of the Korean Society of Pressure Vessels and Piping
• /
• v.7 no.2
• /
• pp.34-41
• /
• 2011

Wrought nickel-base superalloys are being considered as the structural materials in very-high temperature gas-cooled reactors. To understand the effects of impurities, especially oxygen, in helium coolant on the mechanical properties of Alloy 617, creep tests were performed in high temperature flowing He environments with varying $O_2$ contents at 800, 900, and $1000^{\circ}C$. Also, creep life in static He was measured to simulate the pseudo-inert environment. Creep life was the longest in static He, while the shortest in flowing helium. In static He, impurities like $O_2$ and moisture were quickly consumed by oxidation in the early stage of creep test, which prevented further oxidation during creep test. Without oxidation, microstructural change detrimental to creep such as decarburization and internal oxidation were prevented, which resulted in longer creep life. On the other hand, in flowing He environment, surface oxides were not stable enough to act as diffusion barriers for oxidation. Therefore, extensive decarburization and internal oxidation under tensile load contributed to premature failure resulting in short creep life. Limited test in flowing He+200ppm $O_2$ resulted in even shorter creep life. The oxidation samples showed extensive spallation which resulted in severe decarburization and internal oxidation in those environments. Further test and analysis are underway to clarify the relationship between oxidation and creep resistance.

• Journal of Korean Society of Environmental Engineers
• /
• v.30 no.2
• /
• pp.161-167
• /
• 2008

Using an experimental method named filtration-permeation, the influence of sedimentation during filtration was studied for the suspensions composed of particles and that of flocs. The average specific cake resistances measured by filtration do not give accurate values because of the sedimentations during filtration, but the permeation data give quite accurate values. The prolonged permeation rates for the cake formed from particulate suspension do not change, but that rate from the floc filtration changes by the sweeping of flocculant. It is proposed that the cake compressibility can be measured with one set of filtration-permeation experiment by step increase of pressure during permeation period. The another experimental method which can shorten experimental time for floc filtration using filtrationpermeation is also proposed.

• The Research Journal of the Costume Culture
• /
• v.8 no.6
• /
• pp.806-821
• /
• 2000

Each and everything named fashion together with clothes were limited in the boundary of women and men's wear has been slow and narrow in changing speed compared to women's, even there are some differences in accordance time. But maintaining the basic features, men's wear in the latter 20th century has undergone diverse change in the part of materials such as various synthetic fiber, glass, metal, artificial leather and the see-through fabric able to seeing the body wearing the clothes. Therefore, the aim and definition of this study is to present the systematic framework giving help to develop men's wear design newer and more various by considering moulding of materials which existing men's wear could not show up and by grasping material trend of men's clothes in 1990s. The results of the study were summarized as follows : (1) Material containing lustering is categorized as Velvet, Silk, Lustering materials by synthetic fiber and Lustering materials by additional substance. The Velvet generally acknowledged having something to feel womanly image shows the bisexual character coexisting feature of men and women after grafting with men'fashion. The Silk was endowed the role as means of pleasure to express beyond boundary of sex breaking the existing consciousness which men should wear male clothes, not considering differences between men and women. The lustering made by synthetic fiber expressed modern sensitivity aesthetically to the suit. The lustering materials made by additional substance is seen mixed masculine character with womanly character. (2) See-through materials are acknowledged as decadence beauty caused by expanding subjective awareness in beauty. (3) Materials by the sorts of Net is categorized as Lace, Knit The Lace expression seemed to emphases the human liberation of men and women and the humanity from liberation of subjecthood. The Knit can be felt both woman's image and man's image as bisexual image, not raising only one side sex. (4) Elastic materials offered the opportunity to approve exposure in a time when exposure of men's body was not granted ethically. (5) Leather was shown as indication of social status and inferiority and expression of collective resistance against sexual stagnation of men and women.

• Proceedings of the Korean Society of Plant Pathology Conference
• /
• 2003.10a
• /
• pp.93.1-93
• /
• 2003

A growth chamber fumigation was conducted to evaluate the ozone (O3) on the physiology of three hot pepper, Capsicum annuum L. cultivars, 'dabotab', 'buchon' and 'pochungchun'. Thirty-day old plants were exposed to O3 of 120 nl 1-1 in the chambers for 8 h d-1 for 3 days. Foliar damage due to O3 was different from the varieties, 'dabotab'was most sensitive to O3, 'pochungchun' was medium, and 'buchon' was resistant. Ozone symptom on the leaves was bifacial necorsis. Photosynthesis and stomatal conductance were decreased due to O3 treatment, but they were not much different from the variety. Decreases of net photosynthesis by O3 were 56％, 40％ and 35％ on 'dabotab', 'buchon' and 'pochungchun', respectively Decreases of stomatal conductance by O3 were 66％, 63％, and 50％ on each varieties. Ozone closed the stomata and decrease net photosynthesis on hot peppers regardless of the variety. Light curves on the three varieties were showing similar patterns that O3 damage on net photosynthesis were started at the low levels of light with or without the visible injury, Assimilation-internal CO2 concentration curves of the three cultivars were not different due to the treatment. It means there was not significant biochemical damage Inside the leaves by O3. In conclusion, ozone closed the stomata and damaged light capturing system of the pepper leaves with or without the visible damage. Although visible damage of the leaves could be a good indicator of O3 resistance, the ecophysiological change by O3 were not proportional to the amout of visible injuries

• Journal of the Korean Geosynthetics Society
• /
• v.5 no.1
• /
• pp.15-23
• /
• 2006

Sand Compaction Pile and Stone Column method have been used in widely during several decades as a technique to reinforce soft soils and increasing ultimate bearing capacity, accelerate consolidation settlement of the foundation ground. Stone column method, making a compaction pile using crushed stone, is a soft ground improvement method. However, stone column method is difficult to apply to the ground which is not mobilized enough lateral confine pressure because no bulging failure resistance. Hence, in present study, development the geogrid reinforced stone column system for settlement reduction and wide range of application of stone columns. To develop this system, triaxial compression tests were conducted for evaluation which is about behavior characteristics of stone column on replacement rate and confine pressure. Then, 3-dimensional numerical analysis were evaluated for application of the GRSC (geogrid reinforced stone column) system as evaluate behavior characteristics and settlement reduction effect of stone column reinforced by geogrid on types and reinforcing depth change of geogrid.

• Journal of Environmental Science International
• /
• v.6 no.2
• /
• pp.125-131
• /
• 1997

The mechanism of stomatal closing in response to $O_2$ was indirectly investigated by using $H_2O_2$ which is the intermediate product of $O_2$ metabolites. Stomata in epidermal strips close in response to $H_2O_2$. The effect of $H_2O_2$ on stomatal closing was dependent on the concentration of $H_2O_2$. 10 ppm $H_2O_2$ showed a clear effect on stomatal closing and 1000 ppm $H_2O_2$ induced complete stomatal closing after the treatment of 3 hours. Stomatal closing by $H_2O_2$ in intact leaf was also observed by measuring the diffusion resistance with porometer. It was found that the stomatal closing by $H_2O_2$ was not mediated by $Ca^{2+}$, and that was a different result observed in stomatal closing by water stress. Reversely, $Ca^{2+}$ showed a great inhibition on stomatal closing. The leakage of K+ in epidermal strips was doubled in response to $H_2O_2$ when it was campared to the control. 10 ppm $H_2O_2$ decreased photosynthetic activity. Fv/Fm representing the activity of Photosystem II was reduced about 4 % in 10 ppm $H_2O_2$ and 8 % in 100 ppm $H_2O_2$ In the treatment of 1.5 hour. However, stomatal closing by 10 ppm $H_2O_2$ was reduced about 56 %. According1y, it can be suggested that stomatal closing by $H_2O_2$ is related with the decrease of photosynthetic activity, but it was chiefly induced by the change of the membrane permeability. Key words Commelina communis, stomatal closing, $H_2O_2$, $Ca^{2+}$, photosynthesis.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.7 no.4
• /
• pp.104-112
• /
• 2012

This study involves investigating the correlation between variation of internal structure and heating temperature of alkali-activated fire protection materials using fly ash. Dehydration and micro crack thermal expansion occur in cement hydrates of cementitious materials heated by fire. Internal structure difference due to both the dehydration of cement hydrates and pore solution causes and influences changes in the properties of materials. Also, this study is concerned with change in microstructure and dehydration of the alkali-activated fire protection materials at high temperatures. The testing methods of alkali-activated fire protection materials in high temperature properties are make use of TG-DSC and mercury intrusion porosimetry measurements. The study results show that the alkali-activated fire resistant finishing material composed of potassium hydroxide, sodium silicate and fly ash has the high temperature thermal stability. These thermal stability is caused by the ceramic binding capacity induced by alkali activation reaction.