• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.4
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• pp.723-736
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• 1992

Most degeneating diseases and back pains in the orthopaedic disease are originated from the unbalance of stress distribution in the low-lumbar spine. Therefore the stress analysis of lowerback is indispensible to the clinical diagnosis for the developing reason and the developing process of diseases. Therefore the same model materials as following are eveloped to analyze the stress distributions of lower-back by photoelastic experiment. The verterbral body and the process are molded from epoxy resin(the weight ratio of Araldite and hardner is 10 to 3), models are geometrically identical to them in vivo respectively and the ratio of their elastic modulus to that of model material is 1 to 10. It is assured that KE-1300 Silicon(E=0.8MPa), TSE-3562 Silicon(0.5MPa) and the composite silicon(3MPa) (the weight ratio of KE-1300 silicon and Jioreal : 10 to 4) are respectively effective as the model materials of ligament, musles and intervertevral disc which is essential to the movement of low-lumbar spine. All the elements associated with the movement of the low-lumbar spine are molded through the molding method developed in this research and assembled with the angles between the verterbra and the disc in the normal human lumbosacral spine. The stress distributions of the assembled model are analyzed by photoelastic experiment. It is certified by comparing the results of photoelastic experimebt with the clinical situations that the loading dveice and the loading conceptions used in this paper are effective.

• Applied Chemistry for Engineering
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• v.29 no.1
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• pp.37-42
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• 2018

In order to increase the compatibility of polypropylene (PP) and kenaf fiber (KF) felt, PP/KF and PP/KF/polyurethane (PU) felt composites were prepared by treating KF with three kinds of silane coupling agents. The concentration of silane coupling agents was fixed at 1 wt%. The chemical reaction between KF and silane coupling agents was confirmed by the existence of Si-O-Si and Si-O-C functional group bands appeared on FT-IR and X-ray photoelectron spectra (XPS). Thermal properties of PP/KF composites were investigated by DSC and TGA, and the thermal stability of PP/KF composites with treated KF increased. Based on tensile, flexural and impact properties of PP/KF and PP/KF/PU composites, 1-2 wt% of (3-aminopropyl)triethoxysilane (APS) contents were the optimum formulation as a compatibilizer. The tensile and flexural strength of the felt composites treated with the silane coupling agents were improved. This is mainly due to the improvement in the compatibility between PP and KF, which was confirmed by SEM images of the fractured surfaces after tension tests.

• Applied Chemistry for Engineering
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• v.29 no.5
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• pp.503-509
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• 2018

In this study, we used the ultrasonic extraction process as a method to extract antioxidant substances from kudzu, and measured the content of iso-flavonoids puerarin, daidzein, daidzin contained in kudzu. The response surface methodology which is a statistical analysis method for optimizing the extraction amount of iso-flavonoids from the kudzu and the process condition for maximizing the yield was applied. It is the final objective of this study to effectively derive the condition of the process that matches the target response with a minimum number of experiments and analyze the effect of each process condition on the response. In the response surface methodology, the central composite design was applied and the optimum condition was analyzed, and the three independent variables were set to ultrasonic irradiation time, volume ratio of ethanol/ultrapure water, ultrasonic irradiation power. Using the response surface methodology, the optimum conditions with the maximum extraction yield and the content of iso-flavonoids were evaluated as ultrasonic irradiation time (24.75 min), ethanol / ultrapure water volume ratio (39.75 vol%), ultrasonic irradiation power (592.36 W). The overall satisfaction level appears as high as 0.8938, which is recognized at a significance level within 5%. As a result of analyzing the optimization process, it was confirmed that the ultrasonic irradiation time is the factor that most affects the responses.

• Journal of Korea Port Economic Association
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• v.36 no.1
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• pp.129-140
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• 2020

In the future, the global container handling market will be reorganized into larger ships and shipping alliances, and the bargaining power of shipping companies will be further strengthened. Therefore, the global terminal operator (GTO), which has a global network, vast experience, and operational know-how, is expected to strengthen its competitiveness. In Korea, the central government promoted the development of GTOs in the mid-2000s, but it failed, mainly due to disagreements between port stakeholders. In this study, the macroeconomic indicators that have the same effect in all regions were used to analyze GTO management performance. In the short term, it could be used to establish the business strategy of domestic terminal operators based on changes in macroeconomic indicators. In the long term, it would be used to establish a promotion strategy for GTOs in Korea. The results of analyzing the impact of macroeconomic indicators on the GTO's profit show that the GTO's profit is significantly affected by cargo handling capacity, the consumer price index of the United States, the Shanghai Composite Index, the Crude Oil Price, and the London Inter-bank Offered Rate (LIBOR). However, the scale of impact was not significantly different between public and private GTOs.

• Journal of Korean Society of Steel Construction
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• v.22 no.2
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• pp.139-150
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• 2010

Reinforced-concrete (RC) columns are frequently designed and constructed. other types of columns includes composite types such as concrete-filled tube columns (CFT). Hollow RC columns may be effective in reducing both the self weight of columns and total amount of materials used. This is due to the fact that a hollow RC column possesses larger moment of inertia than that of solid RC columns of same cross sectional area. Despite the effectiveness the hollow RC column has not been popular because of its poor ductility performance. While the transverse reinforcements are effective in controlling the brittle failure of the outside concrete, they are not capable of resisting the failure of concrete of inner face which is in unconfined state of stress. To overcome these drawbacks, the internally confined hollow reinforced concrete (ICH RC), a new column type, was proposed in the previous researches. In this study, the fire resistance performance of the ICH RC columns was analyzed through a series of extensive heat transfer analyses using the nonlinear-material model program. Also, effect of factors such as the hollowness ratio, thickness of the concrete, and thickness of the internal tube on the fire resistance performance were extensively studied. Then the factors that enhance the fire-resistant performance of ICH RC were presented and analyzed.

• Journal of the Korean Wood Science and Technology
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• v.40 no.6
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• pp.397-405
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• 2012

Installation of deck has been on the rise in Korea recently, but there is little of research on the safety of deck. One of the major factors affecting maneuverability of a pedestrian is frictional force between an outsole of shoe and a surface of the deck. The frictional force is influenced by many factors such as raw material variance of deck, surface convex shape of deck, outsole patterns of shoes, and moist condition of contact surface between deck and shoes. This study focused on evaluating the effect of these factors on the frictional force. Two kinds of deck, which were made of natural wood and wood plastic composite, were used in this study. The surface convex patterns of deck were classified to single nonslip (longitudinal groove processing) and double nonslip (longitudinal and transverse groove processing). Two kinds of shoe outsole patterns, W-shape and rectangle-shape, were used in the tests. Also, the friction tests were carried out at dried surface conditions and water-adsorbed surface condition.

• Korean journal of food and cookery science
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• v.31 no.2
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• pp.175-184
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• 2015

The purpose of this study was to determine the optimal mixing ratio of Agaricus blazei Murill powder and butter in the preparation of cookies. The experimental design utilized herein was based on central composite design for response surface methodology, which included 10 experimental points, including 2 replicates for Agaricus blazei Murill and butter. The physical, mechanical, and sensory properties of the test were measured, and these values were applied to the mathematical models. A canonical form and perturbation plot showed the influence of each ingredient on the final mixed product. The spread ratio increased significantly with an increase in Agaricus blazei Murill powder and butter (p<0.05). The response surface methodology was applied to evaluate the effect of Agaricus blazei Murill powder and butter on cookie moisture and color (L, a) (p<0.001). Sensory evaluation showed significant values for color (p<0.05), flavor (p<0.05), texture (p<0.05) and overall quality (p<0.01) in the predicted model. The optimum formulation by numerical and graphical methods was calculated as follows: Agaricus blazei Murill powder 3.63 g, butter 55.37 g.

• Korean Journal of Clinical Pharmacy
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• v.15 no.2
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• pp.105-117
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• 2005

Following intracoronary stenting, antiplatelet therapy lead to greater protection from thrombotic complication. A few data are available about the effect of clopidogrel versus cilostazol, an antiplatelet commonly used after intracoronary stenting. To evaluate the efficacy and safety of clopidogrel plus aspirin compared with those of cilostazol plus aspirin in coronary stenting and to evaluate the efficacy of clopidogrel loading dose prior to coronary stealing in clopidogrel group. Data were retrospectively collected from medical charts of patients who had undergone coronary stenting and received either clopidogrel with or without loading 300 mg followed by 75 mg/d (n=58), or 200 mg/d cilostazol(n=72) for 1 year, between January 2000 and May 2002. All patients in both groups received aspirin 200 mg/d throughout the study. The primary endpoints at 7, 30, 180 and 365 days after stealing were the composite of death, Myocardial Infarction, stroke, angina, and revascularization in the intent to treat population and restenosis at follow up angiography. The secondary endpoints were the incidence of bleeding complications at 7, 30, and 365 days, and durg adverse effects at 365 days after stenting. At 180 and 365 days after stenting, the combined primary endpoints were significantly reduced in clopidogrel plus aspirin group (relative risk 0.39; 95% CI 0.17 to 0.92; p=0.021, RR 0.43; 95% CI 0.22 to 0.84; p=0.0085, respectively). However, the combined primary endpoints were not significantly different between the two groups at 7 and 30 days (p:1.00, p=0.79, respectively). Angiographic restenosis rate was 14.3% in clopidogrel plus aspirin uoup and 32.1% in cilostazol plus aspirin group (p=0.19). 300mg of clopidogrel loading dose did not significantly reduce the combined primary endpoints at 30 days after stenting (RR 0.14; 95% CI 0.01 to 2.65; p=0.23). The rate of bleeding complications and drug adverse effects were not different between the two groups. In patients undergoing intracoronary stenting, clopidogrel plus aspirin therapy is more beneficial than cilostazol plus aspirin in reducing major adverse cardiac events with similar rate of bleeding complication. A loading dose of clopidogrel did not lead to a statistically significant reduction in major adverse cardiac events.

• Journal of the Korea Concrete Institute
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• v.25 no.6
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• pp.631-639
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• 2013

Non-linear finite element analysis for newly developed precast concrete details for beam-to-column connection which can be used in moderate seismic region was carried out in this study. Developed precast system is based on composite structure and which have steel tube in column and steel plate in beam. Improving cracking strength of joint under reversed cyclic loading, joint area was casted with ECC (Engineering Cementitious Composites). Since this newly developed precast system have complex sectional properties and newly developed material, new analysis method should be developed. Using embedded elements and models of non-linear finite element analysis program ABAQUS previously tested specimens were successfully analyzed. Analysis results show comparatively accurate and conservative prediction. Using finite element model, effect of axial load magnitude and flexural strength ratio were investigated. Developed connection have optimized performance under axial load of 10~20% of compressive strength of column. Plastic hinge was successfully developed with flexural strength ratio greater than 1.2.

• Journal of the Korean Society of Food Science and Nutrition
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• v.39 no.2
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• pp.319-323
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• 2010

This study was carried out to investigate proximate compositions, acidity, and soluble solids of various blueberries produced in Korea and to prepare jam with optimized overall palatability by a response surface methodology. Proximate compositions were 75~88% in moisture, 0.32~0.62% in crude protein, 0.12~0.39% in crude lipid, and 10.18~23.80% in carbohydrate. Acidity and soluble solids of blueberries showed 0.82~1.58% and $7~12^{\circ}Brix$, respectively. The effect of sucrose ($X_1$, 200~300 g), pectin ($X_2$, 0~10 g), and citric acid ($X_3$, 0~0.5 g) on overall palatability of blueberry jam were investigated at five levels using a central composite design. Overall palatability of blueberry jam showed maximum score in 200 g blueberry, 248 g sucrose, 4.8 g pectin, and 0.26 g citric acid.