• Structural Engineering and Mechanics
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• v.78 no.3
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• pp.231-253
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• 2021

Pure bending loading conditions are not frequently occurred in practical engineering, but the flexural researches are important since it's the basis of mechanical property researches under complex loading. Hence, the objective of this paper is to investigate the flexural behavior of concrete-filled rectangular steel tube (CFRT) through combined experimental and numerical studies. Flexural tests were conducted to investigate the mechanical performance of CFRT under bending. The load vs. deflection curves during the loading process was analyzed in detail. All the specimens behaved in a very ductile manner. Besides, based on the experimental result, the composite action between the steel tube and core concrete was studies and examined. Furthermore, the feasibility and accuracy of the numerical method was verified by comparing the computed results with experimental observations. The full curves analysis on the moment vs. curvature curves was further conducted, where the development of the stress and strain redistribution in the steel tube and core concrete was clarified comprehensively. It should be noted that there existed bond slip between the core concrete and steel tube during the loading process. And then, an extensive parametric study, including the steel strength, concrete strength, steel ratio and aspect ratio, was performed. Finally, design formula to calculate the ultimate moment and flexural stiffness of CFRTs were presented. The predicted results showed satisfactory agreement with the experimental and FE results. Additionally, the difference between the experimental/FE and predicted results using the related design codes were illustrated.

• Journal of Haehwa Medicine
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• v.8 no.1
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• pp.625-641
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• 1999

Aging occurs as a part of maturation as the time progresses which manifests in the human body causing morphological and functional degeneration, eventually leading to death. This experimental study was conducted to investigate a herbal formula to fortify the heart with easy clinical applications. Sungshimsan was chosen to study its effects in heart lipid peroxide and metabolic enzyme system in senescence induced rats. After pre-treatment of Sungshimsan for 2 weeks at the dosage of A (100mg/kg), B (250mg/kg), C (350mg/kg), and D (500mg/kg), a lipid peroxide and metabolic enzyme system changes of the heart were meaured in 32 weeks old rats. The following results were obtained in this study: 1. The contents of lipid peroxide was significantly reduced in the experimental groups treated with greater than 2 weeks at 250mg/kg. 2. The enzymatic activity of cytochrome P-450, cytochrome b5, and NADPH-cytochrome P450 reductase were significantly decreased in the 250mg/kg, 350mg/kg, and 500mg/kg experimental groups. 3. The activity of glutathione and glutathione S-transferase were significantly increased in the 250mg/kg, 350mg/kg, and 500mg/kg experimental groups. 4. The activity of glutathione reductase and glutathione peroxidase were not influenced compared to the control group. 5. The activity of ${\gamma}$-glutamylcystein synthetase was significantly increased in the 250mg/kg, 350mg/kg, and 500mg/kg experimental groups. 6. The activity of enzymes detoxificatioon superoxide dismutase and catalase were not influenced compared to the control group. Summarizing above results suggest that the Sungshimsan has profound effects in the heart lipid peroxide, free radicals, and delaying the heart aging process. Further clinical researches and application can be anticipated on the topic of senility and gerontology.

• Journal of Korea Water Resources Association
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• v.40 no.10
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• pp.833-840
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• 2007

The experimental study was carried out to investigate propagation distance of flood wave due to levee breach in a flat inundation area without obstacle. Hitter solution was considered to formulate the experimental results and a representative form was written referring to existing researches. As a result of experiments, it was found that the propagation velocity of the wave front in inundation area was significantly influenced by the initial water level in a channel, which was similar to flow in a channel due to dam break. An empirical formula was also suggested using the experimental results. The dimensionless propagation distance L can be written as the power function of dimensionless time T Coefficients k and m were varied with the dimensionless time T whereas k and m in Ritter solution were 2 and 0, respectively. The variation of coefficients in the relationship between L and T was influenced by the water depth in the inundation area and the fact proved that the changing points of L in the slope of relationship between L and T are the same to those of relationship between the dimensionless maximum water depth in the inundation area, $h_{max}$ and L.

• Herbal Formula Science
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• v.22 no.1
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• pp.177-192
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• 2014

Objective : In order to investigate the effect of Curcumae Longae Rhizoma(CLR) extract on the hepatocellular carcinogenesis and acute liver damage induced by diethylnitrosamine(DENA) and $CCl_4$ in rats. Methods : Experimental groups were subdivided into four; normal group (Nor), acute liver damage and hepatocellular cancer inducing control group (Con), and CLR extract 200mg/kg/day (CAA) or 400mg/kg/day (CAB) administered groups to Con. Thereafter the changes of the body weight, the liver weight and the weight of liver/100g body weight, total cholesterol, HDL cholesterol, triglyceride, the activities of AST, ALT, ALP, LDH, AFP, SOD, catalase were measured. And we observed by optical and electron microscopy. Result : 1. The body weight was decreased in Con compared with Nor for 5 weeks, but increased in Con compared with Nor from 6 week to 9 week. During experimental period of total 9 weeks, CAA and CAB were increased compared with Con. 2. The liver weight was increased significantly (p<0.05) in Con compared with Nor. The weight of liver/100g body weight was increased significantly (p<0.05) in Con compared with Nor and decreased significantly (p<0.05) in CAB compared with Con. 3. The level of total cholesterol was increased in Con and CAA compared with Nor, but there was not statistically significant. The level of triglyceride was decreased in Con compared with Nor. But increased in CAA and CAB compared with Con. The level of HDL-cholesterol was significantly increased (p<0.05) in CAA and CAB compared with Con. 4. The activities of AST, ALT were increased in Con compared with Nor, but decreased in CAA compared with Con, significantly decreased (p<0.05) in CAB compared with Con. 5. The activities of ALP, LDH were increased in Con compared with Nor, but decreased in CAA and CAB compared with Con. 6. The activities of AFP was increased significantly (p<0.05) in Con compared with Nor, but decreased significantly (p<0.05) in CAA and CAB compared with Con. 7. The activities of SOD were increased in Con, CAA and CAB compared with Nor, but decreased in CAA and CAB compared with Con. The activities of Catalase was more increased in CAA and CAB compared than Con. 8. The results of light microscopical observation, a number of hepatocytes were damaged in Con compared with Nor and CAB. 9. According to the electron microscopical observation, irregular nuclear membrane, condensed nucleoplasm was observed in Con, the experimental group was observed in the nucleus of the well-preserved and evenly developed nucleoplasm. Conclusions : These results suggest that administration of CLR extract suppress or retard on the hepatocellular carcinogenesis and acute liver damage induced by DENA and $CCl_4$ in rats.

• Herbal Formula Science
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• v.15 no.2
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• pp.35-45
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• 2007

Objective : The purpose of this report was to provide the information activity and safety of Palmul-tang by analyzing domestic/international papers and theses about Palmul-tang, Methods: Domestic/international papers and theses related to Palmul-tang were reviewed and analyzed, These papers were then classified by year, experimental method and subject, Results: The following results were obtained in this study. 1. The study of Palmul-tang started from 1985 and was continuously increased. The study was mainly forcused on experimental model rather than clinical study. 2. As these studies were classified by subject, papers related to immune intensification were most abundant by 20 papers, Besides there were several papers related to cardiovascular activity, reproductive activity, anti-apoptotic activity and cerebral hemodynamics. 3. Among the papers related to immune intensification. the studies on recovery of fatigue were mostabundant by 10 papers and the studies of on immune cell and cytokine express were six. In addition to. several studies were associated with anti-cancer activity and anti-allergic activity. Recovery of fatigue was determined by measurement of fatigue markers in a living body such as lactate. CPK, pyruvate and triglyceride and assessment of exercise capability of animals such as swimming test. slopped plate test. Rota-rod test, and activity cage test after Palmul-tang treatment. 4. According to experimental data. it is supported that Palmul-tang has been used as Qi and Blood intensifier with immune intensification and recovery of fatigue. 5. The paper related to safety of Palmul-tang was only one paper which is studied on acute toxicity of Palmul-tang with experiment with ICR mouse. There was no study on evaluating safety by observing liver and kidney functions after Palmul-tang treatment Conclusion: Palmul-tang is being used in various ways associating with immune intensification. cardiovascular activity and reproductive activity. However. studies on efficacy and mechanism of Palmul-tang should be conducted at the molecular biology level and studies on safety of Palmul-tang need to be completed at the clinical level.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.12
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• pp.8-14
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• 2019

A drop structure, one of the representative river-crossing structures, is constructed to stabilize a riverbed. On the other hand, the structure interrupts the continuity of the river and causes the destruction of the hydro-ecological environment. Therefore, laboratory experiments of a natural type of drop structure with low differences were performed, and the empirical formula of a local scour hole is proposed. Four experimental flow rates were tested for various types of the drop structure models with 28 test cases. Based on the scour test, it was confirmed that the maximum scour depth occurs rather than the result of applying the previously proposed scour depth formulae. Correlation analysis of the major factors of scour hole at the downstream of the drop structure revealed a strong correlation between the upstream flow characteristics, drop structure height, and total crossing length of the drop model. In addition, the depth and length estimation formula of the maximum scour hole were proposed using the dimensionless variables and validated. In the future, it is also expected that more accurate scour prediction and calculation can be derived by conducting experimental studies and numerical analysis considering the various bed materials and flow conditions.

• Clinical and Experimental Pediatrics
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• v.51 no.7
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• pp.704-712
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• 2008

Purpose : A prospective, controlled trial was conducted to evaluate growth, efficacy, safety and nutritional status for very low birth weight infants fed with human milk fortified with Maeil human milk fortifier (Maeil $HMF^{(R)}$; Maeil Dairies Co., Ltd.). Methods : We enrolled 45 premature infants with a birth weight <1,500 g and gestational age <33 weeks, who were born at Dong-A University Hospital from October, 2006 through December, 2007. They were divided into 2 groups: infants in one group were fed with human milk fortified with $HMF^{(R)}$, and the second were fed with preterm formula. Growth, biochemical indices, feeding tolerance, and other adverse events in each group were assessed serially and compared relatively. Follow-up data were also collected after discharge at 1, 3, and 6 months corrected age. Results : Characteristics of the 2 groups including average gestational age, birth weight, sex, respiratory distress syndrome, patent ductus arteriosus, and other adverse events (sepsis, retinopathy of prematurity, and intraventricular hemorrhage) showed no significant difference. Average feeding start day ($8.00{\pm}3.27d$ vs. $8.86{\pm}5.37d$) (P=0.99) and the number of days required to reach full feeding after start feeding ($41.78{\pm}20.47d$ vs $36.86{\pm}20.63d$) (P=0.55) were not significantly different in the group fed human milk fortified with $HMF^{(R)}$ when compared with the group that was fed preterm formula. The duration of total parenteral nutrition and the incidence of feeding intolerance also showed no differences between the 2 groups. Although infants fed with human milk fortified with $HMF^{(R)}$ showed faster weight gain than those fed with preterm formula at the end stage of the admission period, other growth indices of the two groups showed no significant difference. No significant correlations were found between the 2 groups with regard to weight gain velocity, height gain velocity, head circumference velocity, and post-discharge follow up growth indices. Conclusion : Premature infants fed human milk fortified with $HMF^{(R)}$ showed no significant difference compared with those fed preterm formula in growth, biochemical indices, and adverse events. Using human milk fortifier can be an alternative choice for very low birth weight infants, who need high levels nutritional support even after discharge from NICU.

• Journal of the Korean Society of Industry Convergence
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• v.5 no.1
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• pp.65-74
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• 2002

This paper intends to investigate such effects through experiments. The contents of the investigation are effects of position of repeated loading and unloading, passing frequency. For the purpose of the investigation an experimental load-deflection system is developed and the system is possible to measure deflection of the wall and earth pressure due to different size of strip loading and cyclic loading. The findings from the experiments are as follows: 1. As repeated loading approaches to the wall, the measured horizontal residual earth pressure agrees well with Rowe's empirical formula, while as the loading is far from the wall the earth pressure consists with Boussinesq's and Spangler's formulas. Also it is found that below 0.6m depth from ground surface the effects of repeated loading can be nearly neglected. 2. From comparison analyses of earth pressure theories and experimental results, a reagression equation is suggested herein, and earth pressure at any depth and maximum earth pressure due to cyclic loading can be estimated from the equation.

• Journal of the Society of Naval Architects of Korea
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• v.44 no.2 s.152
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• pp.64-73
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• 2007

Turbulent flows around yacht sails were calculated to access the applicability of CFD for yacht design. Multi-block grid system was generated by using Gridgen package and Fluent was used to calculate flows around two sail system. A 30ft class sailing yacht designed and tested by KRISO was chosen. The interference effect between main and jib sails was analyzed. Pressure distribution on the sails was obtained and the center of effort was estimated. It was found that the jib angle affects the flow phenomena around a main sail due to the change of inflow angle. The location of center of effort is much different from the empirical formula based on a simple geometrical consideration. The calculated results are compared with the previous numerical and experimental results. Both CFD results are similar, but there are some discrepancies with experimental data. However, it is certain that CFD can be a very useful tool for yacht design.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.32 no.3
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• pp.161-169
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• 2020

Physical experiments have been performed in a wave basin to investigate change of the wave loading on the crown wall under obliquely incident wave conditions. The measurement was carried out with wave incidence angle of 0, 15, 30 and 45°. The pressure transducers were placed on the front and bottom face of the crown wall to obtain horizontal and uplift force as well. It was found that both the horizontal and vertical force decreases with the incidence angle. Based on the analysis of the experimental data, a formula was suggested to estimate the reduction rate of horizontal and vertical forces under obliquely incident waves.