• Journal of the Korean Geotechnical Society
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• v.19 no.5
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• pp.199-210
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• 2003

The development of strain localization within shear zones is frequently observed during soil deformation. In fact, the phenomenon appears to be more often the norm rather than the exception. Conceptually, any soil condition that renders negative work increment is prone to localization. In this study, a broad range of soil and loading conditions are investigated to test this criterion, including: dilative soil subjected to drained shear (standard case), contractive soil sheared under undrained conditions, cavitation in dilative soil in undrained shear, inhomogeneous soils, particle alignment in contractive soils made of platy particles, soils that experience particle crushing, and the shear of low-moisture and/or lightly cemented loose soils. Unique specimens and test procedures are designed to separately test each of these soil conditions in the laboratory According to experimental test results, soil specimens with post-peak strain softening behavior are prone to progressive failure, localization of deformations, and shear banding. The state of stress, the soil density, inherent mechanical and geometrical properties of soil particles, low water content, and heterogeneity can contribute to triggering strain localization. Considering all possible cases of localization, the best method to obtain the critical state line in the laboratory is to use contractive homogeneous specimens subjected to drained shear.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.3
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• pp.187-194
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• 2020

In this study, computational analyses are carried out to investigate the interference flows and the aerodynamic characteristics of a hit-to-kill intercepter due to lateral jets at medium altitude. In addition, the analyses are performed for air and multi-species gas used in the side jet. The results indicate that the position of the barrel shock are shifted upstream and the structure of the shock wave are changed for the multi-species jet when compared to the air jet. As a result, the high pressure region with multi-species jet moves forward and the pitching moment is higher under the same flow condition. Moreover, the inclusion of high temperature effects makes drastic changes in pressure distribution. The jet width is much bigger, and the jet diffuses over wider range in medium altitude than in low altitude, because of the low density of the freestream.

• Women's Health Nursing
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• v.15 no.4
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• pp.344-352
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• 2009

Purpose: The study was to identify influencing factors on fear of falling in postmenopausal women. Methods: With a correlational survey design, 125 postmenopausal women were recruited at the D metropolitan city by a convenience sampling. Fracture risk status was assessed by bone mineral densities (BMD) at lumbar and femur with DEXA method. A structured study questionnaire was used to measure demographic variables, osteoporosis self-efficacy, and fear of falling. Results: Mean age of the subjects was 59 years old and duration since menopause was 9.55 years. Twenty six percent of the subjects belonged to osteoporotic group in fracture risk status. Mean score for fear of falling was 16.10 (SD=5.18) indicating low level, and osteoporosis self-efficacy for exercise and diet was 44.76 (SD=7.41), indicating mid-range level. Factors influencing the fear of falling was longer time since menopause ($\beta=.30$), lower score of osteoporosis self-efficacy for exercise ($\beta=-.26$), poor health perception status ($\beta=-.16$), and presence of chronic disease ($\beta=.16$), and the explained variance was 20%. Conclusion: Although the level of fear of falling was yet low in postmenopausal women, women who had lower self-efficacy of osteoporosis for exercise and poorer health perception felt greater fear of falling. Therefore, an educational program specific to improve osteoporosis self-efficacy and reduce the fear of falling is needed for improving postmenopausal women's psychosocial well-being.

• Journal of Welding and Joining
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• v.15 no.3
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• pp.88-98
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• 1997

Welding defects, such as porosity and spike, have sometimes occurred in deep penetration electron beam welds. These defects are known to be one of the serious problem in electron beam welds. So, effects of active parameters ($a_b$) on bead shape and occurrence of defects in electron beam welds of heavy section 9%Ni steel plates were investigated. Partial penetration welding in flat position, and deep penetration welding of 10 ~ 28mm depth were investigated in this study. It is desirable to select low accelerating voltage and above the surface focus position $a_b$$\geq$1.2 at which a wine-cup shaped bead is obtained to avoid the welding defects such as spike and root porosity. When the accelerating voltage of electron beam was low (90kV), active parameter ($a_b$) did not influence on the bead width, penetration depth and weld defects significantly. However, in case of high voltage ($\geq$120kV), active parameter ($a_b$) was sensitively associated with penetraton depth and weld defects, i.e. when the active parameter (($a_b$) was in the range of 0.6 to 1.0, the depth of penetration was always over the target (23mm), while the depth of penetration was dramatically decreased with further increase of active parameter ($a_b$). The weld defects were decreased with the increase of active parameter $a_b$ resulting in the decrease of energy density of the focused beam in the root part of fusion zone.

• Nutrition Research and Practice
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• v.11 no.6
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• pp.507-516
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• 2017

BACKGROUND/OBJECTIVES: This study aimed at evaluating the dietary intakes of Korean adolescents affected by food insecurity, in comparison with those who were food secure. SUBJECTS/METHODS: The study used one day 24-hour dietary recall data from the $6^{th}$ Korea National Health and Nutrition Examination Survey. The study subjects consisted of 1,453 adolescents of whom 695 were middle school-aged and 758 were high school-aged. Food security status was assessed using the 18-item questionnaire. Nutrient intake was evaluated in terms of nutrient density, insufficient intake, and excessive intake for selected nutrients, in addition to meeting the appropriate range for total energy intake and energy intakes from carbohydrate, sugar, protein, fat, and saturated fatty acids. Food intake was evaluated in terms of food group servings and dietary diversity score (DDS). RESULTS: The percentages of food insecurity were 11.1% for middle school-aged adolescents and 16.8% for high school-aged adolescents. Food insecure middle school-aged adolescents had higher intake of carbohydrate (P = 0.006) but lower intake of fat (P = 0.010) and saturated fatty acids (P = 0.005) than their food secure counterparts although the intake of both groups was in the recommended ranges. Nutrient intake among high school-aged adolescents was generally similar regardless of food security status. Both food secure and insecure adolescents showed insufficient intake of vitamin A, vitamin C, and calcium, and excessive sodium intake. They additionally had low prevalence of meeting appropriate intake ranges for energy, carbohydrate, and sugar. Food intake in terms of food group servings and DDS was also similar regardless of food security status among both age groups, with low intakes of foods from fruit and dairy groups. CONCLUSIONS: Except for a few nutrients among the middle school-aged adolescents, dietary intakes among Korean adolescents did not differ by food security status in this study.

• 한국금형공학회:학술대회논문집
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• 2008.06a
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• pp.39-44
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• 2008

Magnesium alloys have given high attention to the industry of light-weigh as automobile and electronics with aluminium, titanium and composite alloys due to their high strength, low specific density and good damping characteristics. But the magnesium contained structures under high temperature have the problems related to creep deformation and rupture life, which is a reason of developing the new material against creep deformation to use them safely. The purpose of this study is to predict the creep deformation mechanism and rupture time of AZ31 magnesium alloy. For this, creep tests of AZ31 magnesium alloy were done under constant creep load and temperature with the equipment including automatic temperature controller with acquisition computer. The apparent activation energy Qc and the applied stress exponent n, rupture life have been determined during creep of AZ31 Mg alloy over the temperature range of $150^{\circ}C$ to $300^{\circ}C$. In order to investigate the creep behavior. Constant load creep tests were carried out in the equipment including automatic temperature controller, whose data are sent to computer. At around the temperature of $150^{\circ}C{\sim}300^{\circ}C$ the creep behavior obeyed a simple power-law relating steady state creep rate to applied stress and the activation energy for the creep deformation was nearly equal and a little low, respectively, to that of the self diffusion of Mg alloy.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.11
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• pp.975-978
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• 2003

The microwave dielectric properties and the microstructures on B $i_{0.97}$T $m_{0.03}$Nb $O_4$ doped with $V_2$ $O_{5}$ were systematically investigated. B $i_{0.97}$T $m_{0.03}$Nb $O_4$ ceramics sintered at 920-96$0^{\circ}C$ were mainly consisted of orthorhombic and triclinic phases after addition of $V_2$ $O_{5}$. The apparent density increased slightly with increasing the $V_2$ $O_{5}$ addition. The dielectric constants($\varepsilon$$_{r}$) also increased with $V_2$ $O_{5}$ addition(30-45). The Q${\times}$ $f_{0}$ values measured on B $i_{0.97}$T $m_{0.03}$Nb $O_4$ ceramics doped with $V_2$ $O_{5}$ were between 2,000 and 12,000[GHz] when the sintering temperatures were in the range of 920-960[$^{\circ}C$]. It was confirmed that the temperature coefficient of the resonant frequency($\tau$$_{f}$) can be adjusted from a positive value of +10ppm/$^{\circ}C$ to a negative value of -15ppm/$^{\circ}C$ by increasing the amount of $V_2$ $O_{5}$ Based on our experimental results, the B $i_{0.97}$T $m_{0.03}$Nb $O_4$(added $V_2$ $O_{5}$) ceramics can be applied to multilayer microwave devices at low sintering temperatures.ng temperatures.emperatures.ratures.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.11a
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• pp.350-353
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• 2002

The microwave dielectric properties and the microstructures on $Bi_{0.97}Nb_{0.03}O_{4}$doped with $V_{2}O_{5}$ were systematically investigated. $Bi_{0.97}Tm_{0.03}Nb_{0.03}O_{4}$ ceramics sintered at $920-960^{\circ}C$were mainly consisted of orthorhombic and triclinic phases after addition of $V_{2}O_{5}$. The apparent density increased slightly with increasing the $V_{2}O_{5}$ addition. The dielectric $constants(\varepsilon_r)$ also increased with $V_{2}O_{5}$ addition(30-45). The $Q{\times}f_0$ values measured on $Bi_{0.97}Tm_{0.03}NbO_4$ ceramics doped with $V_{2}O_{5}$ were between 2,000 and 12,000[GHz] when the sintering temperatures are in the range of $920-960[^{\circ}C]$. It was confirmed the temperature coefficient of the resonant $frequency(\tau_f)$ can be adjusted from a positive value of $+10[ppm/^{\circ}C]$ to a negative value of $-15ppm/^{\circ}C$ by increasing the amount of $V_{2}O_{5}$. Based on our experimental results, the Bi0.97Tm0.03NbO4(added V2O5) ceramics can be applied to multilayer microwave devices at low sintering temperatures.

• Journal of the Korean Society for Marine Environment & Energy
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• v.2 no.2
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• pp.60-69
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• 1999

In this paper, we have obtained the initial and near-field dilution rates of wastewaters discharged from the ocean outfall of Masan-Changwon municipal wastewater treatment plant from both of field measurements and CORMIX model simulations. In the summer of 1998, water temperature and salinity profiles was measured at 16 stations in the vicinity of the Masan outfall and the dilution rates were analyzed by salinity deficit method. The transport of the wastefields and their initial dilution rates were calculated by CORMIX model using field data as model input. Both of observed and predicted results are shown In very low dilutions with the range of 32～48 from the field data analysis and 29～43 from the model prediction, respectively. This indicates that the water quality in the Masan outfall area can be worsening due to the low dilution rates of diswastewaters, especially, when the ambient currents are very weak in a neap tide and ambient water density is highly stratified in summer.

• Journal of the Korean Society of Clothing and Textiles
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• v.31 no.3 s.162
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• pp.433-439
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• 2007

The effects of nonionic surfactants on detergency and water wetting/retention properties of soiled cotton cloths were reported. Two different soiled cloths were used. soiled cotton cloth 1 was made in the lab. with carbon black, tripalmitin, n-dodecane & palmitic acid on Korea Apparel Testing & Research Institute(KATRI) cotton testcloth and soiled cotton cloth 2(EMPA 101) was purchased from Testfabrics, Inc., USA. The following nonionic surfactants; l.e., Span 20, Tween 20, 40, 60, 80, 21, 61, 81, 65, & 85, were used in the study. The water retention ratio(W/H) values of soiled cotton cloths were decreased, whereas the water contact angle values of soiled cloth were not changed markedly compared with those of unsoiled testcloths. The wetting and water retention of soiled cotton cloth 1 was improved with addition of nonoinic surfactants. The surfactants which have more hydrophilic characterictics or unsaturated hydrophobe tails were effective in improving wetting and water retention properties of soiled cotton cloth 1. The water contact angle values of soiled cotton cloths were extremely low with Span 20, presumably due to the high adsorption density or the surfactant. The detergency of soiled cloths were low in Span 20 and high in Tween 20, 40, 60 & 80 0.1g/dl surfactant solutions. Nonionic surfactants having higher ethylene oxide contents resulted in better detergency. In the range studied, the wetting and water retention of soiled cotton cloths did not show any particular relation to the detergency, whereas the surfactant characteristics, especially HLB values, influenced the detergency of soiled cotton cloths.