• Geomechanics and Engineering
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• v.33 no.3
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• pp.271-277
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• 2023

This article investigates the effect of viscoelastic foundations on the waves' dispersion in a beam made of ceramic-metal functionally graded material (FGM) with microstructural defects. The beam is considered to be shear deformable, and a simple three-unknown sinusoidal integral higher-order shear deformation beam theory is applied to represent the beam's displacement field. Novel to this study is the investigation of the impact of viscosity damping on imperfect FG beams, utilizing a few-unknowns theory. The stresses and strains are obtained using the two-dimensional elasticity relations of FGM, neglecting the normal strain in the beam's depth direction. The variational operation is employed to define the dispersion relations of the FGM beam. The influences of the material gradation exponent, the beam's thickness, the porosity, and visco-Pasternak foundation parameters are represented. Results showed that phase velocity was inversely proportional to the damping and porosity of the beams. Additionally, the foundation viscous damping had a stronger influence on wave velocity when porosity volume fractions were low.

• The Journal of Engineering Geology
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• v.24 no.4
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• pp.631-641
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• 2014

Characteristics of water-level changes in the Temporary Gulpocheon Discharge Channel were identified by observing and analyzing changes in the subterranean water level induced by hydrological stresses the underground aquifer. The subterranean water level refers to the level at which the pressure of subterranean water passing through the corresponding position has an equipotential value that is in equilibrium with the atmospheric pressure at that location. This water level is not fixed but changes in response to hydrological stress. It can be identified by repeatedly measuring the distance from the observation point to the surface of the subterranean water. The subterranean water-level change equation and the variance range of the hydrological curve of subterranean water over 24 hours at the Gimpo-Gimpo National Groundwater Monitoring Network (NGMN) were used as assessment factors. The variance characteristics of the subterranean water at the 18 monitoring system locations were classified into three impact, observational wish, and non-impact. The impact type accounted for 50% of the subterranean water of and accurately reflected the water-level changes due to hydrological stress, showing that distance is the major controlling factor. The observational wish type accounted for 27.8% of the subterranean water, and one of the two assessment factors did not meet the assessment factors. The nonimpact type accounted for 22.2% of the subterranean water. This type satisfied the two assessment factors and represents subterranean water-level changes response to precipitation.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.6
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• pp.599-608
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• 2012

A numerical analysis has been performed through implicit dynamic finite element analysis using the commercial package, ABAQUS in order to investigate effect of laser peening on welding residual stress mitigation of dissimilar metal welds in a safety injection nozzle of integral reactor. The implicit dynamic finite element analysis are compared with the previous experimental results. By comparison, it is identified that the implicit dynamic finite element analysis is valid for residual stress mitigation via laser peening. Implicit static finite element residual stress analysis has been performed for the dissimilar metal welds subject to inner repair welding. The analysis results represent that both axial and hoop residual stresses are tensile on inner surface of safety injection nozzle due to inner repair welding. Also Parametric study has performed to investigate effect of laser peening variables such as maximum impact pressure, duration time of pressure, spot diameter and peening direction on the welding residual stress mitigation. As a result, it is found that laser peening has the preventive maintenance effect to mitigate mainly residual stresses of region near inner surface.

• Journal of Korean Tunnelling and Underground Space Association
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• v.22 no.4
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• pp.435-450
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• 2020

The divergence section of a double-deck tunnel can be divided into a 'widening pre-divergence section', a large cross-section with a cap shape and a 'post-divergence section' where the separation between the main and the branch tunnel is made. Since the cross-section of the widening pre-divergence section is considerably larger than that of the post-divergence section, the influence of excavation due to the different sizes and shapes in the cross-section should be considered in the examination of the tunnel stability. In this study, the effect of the preceding excavation, that is the excavation of the widening pre-divergence section, on excavation stability of the post-divergence section was examined by varying the excavation methods and bench lengths through 3D finite element analysis. The results showed that although the effects of the excavation methods and the bench lengths are not significant on the variation of principal stresses, the preceding excavation causes a relatively large variation on the stresses which may have an impact on the stability of the post-divergence section from the comparison of Stress-Strength Ratio (SSR) between the cases with and without the consideration of the preceding excavation effect by 2D finite element analysis.

• Women's Health Nursing
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• v.5 no.1
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• pp.80-95
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• 1999

The purpose of this study was to investigate the characteristics of low birth-weight infants and their's mothers, and to identify the factors which influenced to delivery of L.B.W infants. The data derived from K. General Hospital and J. obs & gyn clinic in pusan from January, 1998 to August, 1998, which were from mothers of having B. W infants. The factors used for this study were characteristics of general, obstetrical, environmental aspects and physical and psychological life experiences during pregnancy. Analysis of data obtained were computerized statistically by using SPSS 7.5 WIN program. the data were analysed as number, frequency, percentage, t-test and ANOVA. The major results obtained of this study were as follows : 1) Gender that L.B.W infants were male in 47.2% and female in 52.8%, body weight of 2001~2500gm was above 8 in 68.5%, and below 5 in 1.8%. The L.B.W infants with complications were 7, which were 6.5%. The kinds of malformations were the Cleft palate & lip, Hyper-kalemia, Hypoglycemia, Meningocele, CHD, Down syndrome and each of them marked 0.9%. 2) In the general characteristics of pregnant women, the age group of 25~29 years was the most common as 46.3%. Over 35 years of age, elderly gravidas were in 7.5%. the height of 156~160cm was the most common as 52.8%. pregnant women of below 150cm height was in 3.7%. body weight of 51~55kg was the most common as 38%. pregnant women of below 45kg were in 19.4%. The women with smoking and drinking episodes during pregnancy were 1.9% and 25%. In the status of marriage, married women were in 95.4%, unmarried ones were in 1.9%, and unmarried couples were in 2.8%. Iin he obstetrical characteristics of pregnant women, pregnant women with gestational age under 37wks were in 45.4%, and the ones over 38wks were 54.6%. At the methods of delivery, normal spontaneous vaginal deliveries were in 51.9%, which were the most common, cesarian section deliveries were in 47.2%, and breech deliveries were in 0.9%. In the environmental characteristics of pregnant women, 40.8% of pregnant women lived in house or apartments with stairs, 23.1% of them lived in the high altitude. the pregnant women who ran a household without a helper were in 65.7%. In the pregnant women who had underwent life experiences of physical and psychological stress during pregnancy. life experiences of physical stresses were described as persistent fatigue due to lifestyle, traumatic experience, illness, move away with an effort, physical impact caused by discord. life experiments of psychological stresses were describeded as trouble with their husbands, discord with one's husband family, family problems, and conflicts due to environmental factors, etc. The number of the pregnant women who had complications during pregnancy was 32, which was 29.6% totally. Among them, pre-eclampsia was in 12.1% and the premature rupture of membrane in 7.4%. 3) In the analysis of the general, obstetrical, and circumstantial characteristics and L.B.W infants. There were statistical difference significantly between the gestational age of pregnant women(F=12.035, P=.000), and the status of marriage(F=3.207, P=.044), and maternal complication(t=2.344, P=.021) etc.

• Tunnel and Underground Space
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• v.21 no.5
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• pp.394-405
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• 2011

In this paper, we applied coupled non-isothermal, multiphase fluid flow and geomechanical numerical modeling using TOUGH-FLAC coupled analysis to study the complex thermodynamic and geomechanical performance of underground lined rock caverns (LRC) for compressed air energy storage (CAES). Mechanical stress in concrete linings as well as pressure and temperature within a storage cavern were examined during initial and long-term operation of the storage cavern for CAES. Our geomechanical analysis showed that effective stresses could decrease due to air penetration pressure, and tangential tensile stress could develop in the linings as a result of the air pressure exerted on the inner surface of the lining, which would result in tensile fracturing. According to the simulation in which the tensile tangential stresses resulted in radial cracks, increment of linings' permeability and air leakage though the linings, tensile fracturing occurred at the top and at the side wall of the cavern, and the permeability could increase to $5.0{\times}10^{-13}m^2$ from initially prescribed $10{\times}10^{-20}m^2$. However, this air leakage was minor (about 0.02% of the daily air injection rate) and did not significantly impact the overall storage pressure that was kept constant thanks to sufficiently air tight surrounding rocks, which supports the validity of the concrete-lined underground caverns for CAES.

• Nutritional Sciences
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• v.8 no.1
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• pp.42-49
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• 2005

Many of the non-communicable diseases, which are now the major causes of death and disability worldwide, can be linked to our lifestyles, and thus to what eat The life-style related risk factors are - to a great extent - preventable. Public health nutrition (PHN) policies are means through which govemments can have an enornous impact on the reduction of nutrition-related non-communicable diseases, such as diabetes, hypertension, obesity, cancer and cardiovascular disease, by creating and supporting environments which enable healthier food choices and which are conducive to healthy nutrition behavior. More and more countries are developing nutrition policies. Nutrition policies are tools through which governments can intervene and control nutrition-related concerns throughout all levels of society. The need for more concerted action in the Republic of Korea is demonstrated, by showing the lack of priority for nutrition issues. Four recommendations for action are made; the first recommendation places emphasis on the need to implement a structure at the political level, through which nutrition concerns can be addressed, such as a nutrition unit within the Ministry of Health and Welfare. The second recommendation stresses the need for a strong nutrition advocacy strategy, to raise the awareness of the gains that can be achieved by promoting healthy nutrition. The third recommendation calls for more vigorous regulations and stricter enforcement of food and nutrition advertisement, and the fourth recommendation emphasizes the need for a settings-bsed approach to nutrition interventions. Acknowledging the developments that have already occurred in Korea, public health nutrition has yet to become a priority on the agenda of policy makers in Korea.

• Journal of Contemporary Eastern Asia
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• v.11 no.2
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• pp.61-75
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• 2012

The historical turbulence between China and Japan started from the First Sino-Japanese War in 1895, and culminated in Japan's invasion of China during World War Two (the Second Sino-Japanese War) between 1937 and 1945. A series of wars caused huge human and material losses in both countries, and both experienced comprehensive transformations during and after the wars. The impact of this historical turbulence is so long-lasting that it still influences both countries' social psyche. Moreover, it continues casting a long shadow upon the current Sino-Japanese relations. The recent turbulence in Sino-Japanese relations partly stems from the historical turbulence. It is much less violent but can also be emotional and worrisome. It started from the early 1980s (the Japanese history textbook controversy in 1982 and the 1985 anti-Japanese student protests in China), and culminated in the anti-Japanese mass demonstrations in multiple Chinese cities in 2005 (Bush 2010; Gries 2005; Reilly 2012; Stockmann 2010; Weiss 2008). In addition to dramatic demonstrations on streets, there are also other forms of movements, such as war reparations movements, in which Chinese war victims demand reparations from the Japanese state and companies (Rose 2005; Xu and Fine 2010; Xu and Pu 2010). Although the tension has existed for many years and surfaced from time to time, the eruption of the nationwide anti-Japanese movements in China in 2005 still shocked many outside observers. Many scholars have tried to explain the anti-Japanese sentiment within current Chinese society that underlies and drives these social movements. Through careful reexamination of the existing literature, this article proposes an explanation for the anti-Japanese sentiment from a perspective that stresses the shifting state-society interaction in China's Japan policy. Specifically, the totalitarian Chinese state's neglect and suppression of genuine social concerns regarding Japan in earlier years, followed by a relatively liberalized state that tolerates societal participation in Sino-Japanese relations, are an importance source of the anti-Japanese sentiment recently observed in China.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2005.04a
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• pp.55-62
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• 2005

In this paper, a CAB/CAE integrated optimal design system is developed, in which design and analysis process is automated using CAD/CAE softwares, for a complicated model for which parametric modeling provided by CAD software is not possible. CAD modeling process is automated by using UG/OPEN API function and UG/Knowledge Fusion provided by Unigraphics. The generated model is transferred to the analysis code ANSYS in parasolid format. Visual DOC software is used for optimization. The system is developed for PLS(Plasma Lighting System), which is a next generation illumination system that is used to illuminate stadium or outdoor advertizing panel. The PLS system consists of more then 20 components, which requires a lot of human efforts in modeling and analysis. The analysis for PLS includes static load, wind load and impact load analysis. As a result of analysis, it is found that the most critical component is a tilt assembly, which links lower & upper body assembly. For more reliable analysis, experiment is conducted using MTS and compared with the Finite element analysis result. The objective in the optimization is to minimize the material volume under allowable stresses. The design variables are three parameters in the tilt assembly that are chosen to be the most sensitive in stress values of twelve parameters. Gradient based method and RSM(Response Surface Method) are used for the algorithm and the results are compared. As a result of optimization, the maximum stress is reduced by 57%.

• International Journal of High-Rise Buildings
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• v.6 no.3
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• pp.249-259
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• 2017

The use of high-strength steels in construction of highrise and mega building structures can bring about many technological advantages from fabrication to erection. However, key design criteria such as local and lateral stability in current steel design specifications were developed based on tests of ordinary steels which have stress-strain characteristics very different from that of high strength steels. A series of tests on 800 MPa tensile strength steel (HSA800) members are summarized in this paper which were conducted to investigate the appropriateness of extrapolating current ordinary-steel based design criteria to high strength steels. 800 MPa I-shape beam specimens designed according to flange local buckling (FLB) criteria of the AISC Specification developed a sufficient strength for elastic design and a marginal rotation capacity for plastic design. It is shown that, without introducing distinct and significant yield plateau to the stress-strain property of high-strength steel, it is inherently difficult to achieve a high rotation capacity even if all the current stability limits are met. 800 MPa I-shape beam specimens with both low and high warping rigidity exhibited sufficient lateral torsional buckling (LTB) strength. HSA800 short-column specimens with various edge restraint exhibited sufficient local buckling strength under uniform compression and generally outperformed ordinary steel specimens. The experimental P-M strength was much higher than the AISC nominal P-M strength. The measured residual stresses indicated that the impact of residual stress on inelastic buckling of high-strength steel is less. Cyclic seismic test results showed that HSA800 members have the potential to be used as non-ductile members or members with limited ductility demand in seismic load resisting systems. Finally, recent applications of 800 MPa high strength steel to highrise and mega building structures in Korea are briefly presented.