• Journal of the Earthquake Engineering Society of Korea
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• v.15 no.6
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• pp.1-10
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• 2011

This study presents the results of parametric studies of the P-M interaction diagram of hollow prestressed concrete bridge columns. Among the numerous parameters, this study concentrates on concrete compressive strength, prestressing steel reinforcement ratio, effective prestress, the Ds/Do ratio, and the Di/Do ratio. The strength and ductility of hollow prestressed concrete bridge columns were evaluated through quasistatic tests. The P-M interaction diagrams from the codes were different from that of the results, which were in good agreement with AASHTO-LRFD. Nondimensionalized P-M interaction diagrams were developed to predict the design resistance of hollow prestressed concrete bridge columns.

• Journal of the Korean Magnetic Resonance Society
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• v.4 no.1
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• pp.19-28
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• 2000

Authors evaluated alterations of observable metabolite ratios between the cerebral lesion and the contralateral region related to the clinical symptomatic side in levodopa-treated Parkinson's disease (PD) and investigated correlation between age in patients with PD and metabolite ratios of the lesion. Patients with levodopa-treated PD (n = 54) and age-matched normal controls (n = 15) underwent magnetic resonance spectroscopy (MRS) examinations using a stimulated echo acquisition mode (STEAM) pulse sequence that provided 2$\times$2$\times$2 cm3 volume of interest in the selected regions of substantia nigra (SN) and putamed-globus pallidus (PG). To evaluate dependence of metabolite ratios on age, we divided into two groups (i.e., younger and older age). We quantitatively measured N-acetylaspartate (NAA), creatine (Cr), choline-containing compounds (Cho), inositols (Ins), and the sum of glutamate (Glx) and GABA levels and obtained proton metabolite ratios relative to Cr using a Marquart algorithm. Compared with the contralateral region, a significant neuronal laterality of the NAA/Cr ratio in the lesion of SN related to the clinical symptomatic side was established (P = 0.01), but was not established in the lesion of PG (P = 0.24). Also, Cho/Cr ratio tended toward significance in the lesion of SN (P = 0.07) and was statistically significant in the lesion of PG(P = 0.01). Compared with that in the younger age group, NAA/Cr ratio in the older age was decreased in the lesion of SN (P = 0.02), while NAA/Cr ratio was not statistically significant in the lesion of PG ( P = 0.21). Significant metabolic alterations of NAA/Cr and Cho/Cr ratios might be closely related with functional changes of neuropathological process in SN and PG of levodopa treated PD and could be a valuable finding for evaluation of the PD. A trend of NAA/Cr reduction, being statistically significant in older patients, could be indicative of more pronounced neuronal damage in the SN of the progressive PD.

• Korean Journal of Food Science and Technology
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• v.23 no.1
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• pp.25-30
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• 1991

Chicken liver was enzymatically hydrolyzed with an alkaline protease and determined the optimal conditions of reaction temperature and time, pH and enzyme to substrate ratio(E/S ratio) for possible utilization as a protein supplementary ingredient. The functional properties of hydolysate measured were water and oil absorption capacity, emulsifying activity and viscosity and sensory properties were also evaluated. It was found that hydrolysis at $60^{\circ}C$ and pH 8.0 were most effective and the degree of hydrolysis increased with increasing E/S ratio. A decrease in water and oil absorption capacity and an increase in viscosity were found during hydrolysis. The lowest emulsifying activity and highest water absorption were measured for 1/2 hour-hydrolysate and little difference was found for those treated more than 1 hour. The sensory characteristics of odor showed no significant difference among the chicken liver hydrolysates while the brightness increased and red decreased significantly(p<0.01) as the hydrolysis proceeded.

• Nutrition Research and Practice
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• v.1 no.3
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• pp.212-217
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• 2007

This study compared obese children's food group intakes with the new Dietary References Intakes for Koreans (KDRIs) food guides for 5th-6th grade school children. This study also determined the extent of sedentary life styles related with obesity in this area of children. This is it cross-sectional study of 799 school children. The dietitian sent a survey form describing the project and a questionnaire to the subject's family. The questionnaire included child demographics, family history of chronic diseases, the daily servings of five food groups, such as grains, meat and beans, dairy products, fruits, and vegetables. The daily or weekly hours of physical activity, television viewing, and computer usage were also surveyed. Obesity index (%) of the subjects was calculated, and children with an obesity index (%) equal to or greater than 20 were classified as the obese. Among the 799 participants, 50.7% were female. The percentages of the normal and the obese were 691 (86.5%) and 108 (13.5%) respectively. Obese children reported eating less vegetables (p<0.05), more high sugar snacks (p<0.05), and high fat snacks (p<0.05) than normal children. No significant differences in food servings of grains, meats and beans, and fruits, and dairy products between the normal and the obese were shown. Obese children reported fewer hours of physical activities (p<0.05) and more hours of computer usage (p<0.05) than normal children. Girls showed less likelihood of being obese (odds ratio, 0.575, CI (0.38, 0.87), p<0.05). More hours of physical activity significantly decreased the likelihood of being obese (odds ratio, 0.572, CI (0.35, 0.92), p<0.05). Family history of obesity almost doubled the likelihood of obesity in children (odds ratio, 2.653, CI (1.660, 4.241), p<0.05). In conclusion, frequent snacking, inadequate vegetable consumption, and sedentary lifestyle increased significantly the likelihood of obesity in children, which suggest that obesity intervention in this age group should focuse more on those variables.

• Nuclear Engineering and Technology
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• v.4 no.1
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• pp.3-10
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• 1972

In order to verify the contribution of scattered photons in a restricted gamma-cell as a cause of the“before glow”on a thermoluminescent glow curve of natural quartz, the ratio of the scattered to primary radiation contributions (S/P) in the cell is measured and the relationship between the effective“before glow”height ( $h_{b}$) and S/P ratio is quantitatively investigated. The result shows quite good linear relationship between them with a correlation coefficient of ＋0.9, which possibly suggests that the electrons originally released by the photons of reduced energy are trapped in the shallower traps. Moreover, the ratios of $h_{b}$ to total glow area (At) and of effective “before glow”area (Ab) to At are also examined to see the relationships between S/P and each of them, respectively. The relationships are represented by exponential functions in the region of S/P greater than 0.035. Finally, the exposure limit for re-use of the natural quartz as a TLD was found to be approximately 10$^{5}$ R by analyzing total thermoluminescent output and corresponding exposure dose.ose.

• Journal of the Korean Dietetic Association
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• v.16 no.4
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• pp.332-340
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• 2010

This study was conducted to develop an optimal composite recipe for nutritional cookies containing beet powder. Flour was substituted with whole wheat flour containing germinated brown rice powder. The sensory optimal composite recipe was determined by making cookies containing two levels of beet powder (A) or butter (B) according to Central Composite Design (CCD) and by conducting the sensory evaluation and instrumental analysis according to Response Surface Methodology (RSM). Using CCD, the results of physical measurement for ten conditions with two variables were obtained. The values of lightness (L), redness (a), and yellowness (b) were in the range of 36.65~49.03, 22.15~29.31, and 13.96~19.34, respectively. Lightness decreased significantly (P<0.001) and redness increased significantly (P<0.01) upon an increase in beet powder. The results of sensory evaluation showed very significant values in color (P<0.05), texture (P<0.05), flavor (P<0.01), taste (P<0.05), and overall quality (P<0.05), whereas those of the instrumental analysis showed significant values in lightness (P<0.001), redness (P<0.01), spread ratio (P<0.01), and hardness (P<0.05). As a result, the optimal sensory ratio of beet cookie was calculated for beet powder 7.75 g and butter 77.88 g.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.11a
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• pp.615-620
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• 2000

The strength properties of Light-Weighted Soils(LWS) mixed with Expanded Polystrene(E.P.S) are studied. Test results show that when the initial water contents of dredged soils are under 135% and the cement contents are above 1%, Light-Weight Soils are in the appropriate strength range of 2.0 to 4.0kg/㎠. However, E.P.S contents had a little affects on the strength properties of LWS. In the view of E.P.S diagram's effects on LWS, which have expand ratio of 25, 35, 45 and 60, further studies considering of physical properties of original E.P.S beads are needed.

• Steel and Composite Structures
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• v.16 no.6
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• pp.611-637
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• 2014

A single plate shear connection, or shear tab, is a very popular shear connection due to its merit in ease of construction and material economy. However, problems in understanding the connection behavior, both in terms of strength and ductility, have been well-documented. Suggestions or design model for single plate connections in AISC Design Manual have been altered several times, with the latest edition settling down to giving designers pre-calculated design strength tables if the connection details agree with given configurations. Results from many full-scale tests and finite element models in the past suggest that shear strength of a bolt group in single plate shear connections might be affected by yield strength of plate material; therefore, this research was aimed to investigate and clarify effects of plate yield strength and thickness on shear strength of the bolt group in the connections, including the validity of using a plate thickness/bolt diameter ratio ($t_p/d_b$) in design, by using finite element models. More than 20 models have been created by using ABAQUS program with 19.0- and 22.2-mm A325N bolts and A36 and Gr.50 plates with various thicknesses. Results demonstrated that increase of plate thickness or plate yield strength, with the $t_p/d_b$ ratio remained intact, could significantly reduce shear strength of the bolt group in the connection as much as 15 percent. Results also confirmed that the $t_p/d_b$ ratio is a valid indicator to be used for guaranteeing strength sufficiency. Because the actual ratio recommended by AISC Design Manual is $t_p/d_b$ + 1.6 (mm) for connections with a number of bolts less than six and plate yield strength in construction is normally higher than the nominal value used in design, it is proposed that shear strength of a bolt group in single plate connections with a number of bolts equal or greater than seven be reduced by 15 percent and the $t_p/d_b$ ratio be limited to 0.500.

• Journal of The Korean Digital Architecture Interior Association
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• v.11 no.3
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• pp.35-42
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• 2011

The exterior system of buildings, which is the typical curtain wall, has been made with glass and metal. Theses materials, however, have weaknesses such as inadequate insulating quality, short durability, combustibility and toxic substance. On the other hand, Autoclaved Aerated Concrete(AAC) or Autoclaved Lightweight Concrete(ALC) possess the great energy efficiency and the superb insulating quality as substitute of existing exterior system materials. In this research, strength characteristics and bubble dispersion of hydrothermal synthesis process of AAC based on CaO/$SiO_2$(C/S) ratio are analyzed. C/S ratio is determinated and bubble distribution and compressive strength are studied through the test of varied water-to-solid mineral ratio(W/S). In hydrothermal synthesis program, final C/S ratio is determined as 0.7 consider of the manufacturing process and hydrothermal synthesis is done at $180^{\circ}C$ for 7 hours. The analysis shows slurry has about 2,300cP viscosity and 0.56 specific gravity therefore it is expected AAC has the appropriate facility in the manufacturing process and Hydrates of AAC's Expansion.

• Journal of The Korean Society of Agricultural Engineers
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• v.49 no.3
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• pp.51-60
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• 2007

This study was performed to evaluate void ratio, compressive and flexural strengths, and pH properties according to the content ratio of rice husk ash, aggregate size, and neutral treatment time of porous concrete with content of rice husk ash produced as an agricultural by-product. The SEM results for cement mortar with a 5% rice husk ash for the weight of cement formed more C-S-H hydrates due to the $SiO_2$ of rice husk ash. In the XRD test, cement mortar with a 5% rice husk ash for the weight of cement registered a higher peak point of approximately $2{\theta}=20{\sim}25^{\circ}$ compared to cement mortar without rice husk ash. According to the results of the XRD and SEM tests, the $SiO_2$ that was a major chemical element of rice husk ash generated a large amount of calcium hydroxide in the early stage of the hydration process of cement leading to the formation of ettringite. The void ratio of porous concrete with rice husk ash decreased with increasing content ratio of rice husk ash. In addition, the void ratio of porous concrete with rice husk ash decreased compared to porous concrete without rice husk ash. The compressive and flexural strength of porous concrete with a 5% and 10% content ratio of rice husk ash slightly increased compared to concrete without rice husk ash. The pH value of porous concrete rapidly decreased immediately after neutral treatment. Then, it gradually increased and decreased again after 14 days. However, the pH value was nearly the same regardless of neutral treatment time in 28 curing days. Also, for neutral treatment, the pH value of porous concrete showed appropriate pH levels (less than 9.5) in all mixtures for planting at 28 curing days.