• Journal of the Computational Structural Engineering Institute of Korea
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• 제27권5호
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• pp.337-343
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• 2014

This paper presents a continuum-based shape design sensitivity analysis(DSA) method for crack propagation problems using a reproducing kernel method(RKM), which facilitates the remeshing problem required for finite element analysis(FEA) and provides the higher order shape functions by increasing the continuity of the kernel functions. A linear elasticity is considered to obtain the required stress field around the crack tip for the evaluation of J-integral. The sensitivity of displacement field and stress intensity factor(SIF) with respect to shape design variables are derived using a material derivative approach. For efficient computation of design sensitivity, an adjoint variable method is employed tather than the direct differentiation method. Through numerical examples, The mesh-free and the DSA methods show excellent agreement with finite difference results. The DSA results are further extended to a shape optimization of crack propagation problems to control the propagation path.

• Journal of radiological science and technology
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• 제39권1호
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• pp.81-88
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• 2016

The body of the fat tissue increased in obese represented by risk factors such as cardiovascular diseases, diabetes, metabolic disease and dyslipidemia. Such metabolic diseases and the like of the cardiovascular and cerebrovascular disease, hypertension, dyslipidemia, increase in the adipose tissue of the pancreas is known to be a risk factor of these diseases. Study on the diagnosis and treatment of pancreatic cancer was conducted actively, case studies on pancreatic steatosis is not much. In this study, divided into a control group diagnosed with pancreatic steatosis as a result of ultrasonography to evaluation the physical characteristics and serologic tests and blood pressure and arterial stiffness. The control group and the test pancreas steatosis age and waist circumference, body mass index, total cholesterol, HDL cholesterol, LDL cholesterol, and systolic and diastolic blood pressure, fasting blood glucose, arterial elasticity is higher in pancreatic steatosis. And the lower ankle brachial stenosis and HDL-cholesterol were lower than the normal control group, so the pancreatic steatosis harmful to blood vessels.(P <0.05). The difference between the control group and it was confirmed that the pancreatic jibanggun statistically significant. In conclusion, pancreatic steatosis at abdominal ultrasound can predict the risk of metabolic diseases, and there was a correlation with cardiovascular disease.

• Journal of the Korea Academia-Industrial cooperation Society
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• 제22권6호
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• pp.100-107
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• 2021

This study was a descriptive research to investigate the effects of resilience and personality types on the major satisfaction of nursing students. The participants of this study were nursing students who were attending two universities in D city. Data collection was conducted from September 8 to October 6, 2020. The SPSS/WIN 26.0 program was used for data analysis. Frequency and percentage, mean and standard deviation, Pearson's correlation, independent sample t-test, one-way ANOVA, and multiple regression were used for analysis. The results of this study showed that the average recovery elasticity of nursing students was 3.50 points (5 points), personality type was 2.28 points (4 points), and major satisfaction was 3.12 points (5 points). Personality type A was found in 122 people and personality type B in 136 people. It was found that there was a positive correlation between resilience and major satisfaction, which indicates that the higher the resilience, the higher the major satisfaction. The major satisfaction of nursing students was found to be a significant factor influencing college life satisfaction and human relationships in personality type A, showing 46.2% explanatory power. In personality type B, it was found to be a significant influencing factor in grade and human relationships, showing 42.5% explanatory power. From the above study results, it can be inferred that the development of a college application program that can improve human relationships and increase resilience in college life is required to inspire major satisfaction.

• Journal of the Korean Society of Marine Environment & Safety
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• 제28권7호
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• pp.1222-1230
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• 2022

The rotor blade is an important component of a tidal stream turbine and is affected by a large thrust force and load due to the high density of seawater. Therefore, the performance must be secured through the geometrical and structural design of the blade and the blade structural safety to which the composite material is applied. In this study, a 1 MW class large turbine blade was designed using the blade element momentum (BEM) theory. GFRP is a fiber-reinforced plastic used for turbine blade materials. A sandwich structure was applied with CFRP to lay-up the blade cross-section. In addition, to evaluate structural safety according to flow variations, static load analysis within the linear elasticity range was performed using the fluid-structure interactive (FSI) method. Structural safety was evaluated by analyzing tip deflection, strain, and failure index of the blade due to bending moment. As a result, Model-B was able to reduce blade tip deflection and weight. In addition, safety could be secured by indicating that the failure index, inverse reserve factor (IRF), was 1 or less in all load ranges excluding 3.0*Vr of Model-A. In the future, structural safety will be evaluated by applying various failure theories and redesigning the laminated pattern as well as the change of blade material.

• KSCE Journal of Civil and Environmental Engineering Research
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• 제28권6D호
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• pp.791-799
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• 2008

To build the system which has high utilization and usefulness for users, it is necessary to know the information type and use-demand that the use want. The purpose of this study is to forecast the preference and demand of utilization for bus information when bus information is offered through cellular phon. The accomplishments of this research are as follow : Firstly, importance on the level of individual factor and the value of change's figure can be evaluated, using preference analysis on bus information by conjoint analysis. Secondly, by establishing the use-demand model bus information using binary logit model, influence factor on whether or not the use of the user. Finally, ordered probit model was built by use behavior model in payment per call or per month of potential user of bus information. Through call times and sensitive analysis by payment methods, elasticity point, optimal payment fee, and use probability was analyzed. This study make application as basic to efficient bus information policy and to improve use rate of bus information in future because this study make it possible to get preference analysis, use-demand analysis and estimation of optimal payment fee which is reflecting various requirement in use of bus information user.

• KIPS Transactions on Computer and Communication Systems
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• 제6권11호
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• pp.445-452
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• 2017

Electric pole is a supporting beam used for power transmission/distribution which accelerometer are used for measuring a external force. The meteorological condition has various effects on the external forces of electric pole. One of them is the elasticity change of the aerial wire. It is very important to perform modelling. The acceleration sensor is converted into a pitch and a roll angle. The meteorological condition has a high correlation between variables, and selecting significant explanatory variables for modeling may result in the problem of over-fitting. We constructed high deviance explained model considering multicollinearity using the Generalized Additive Model which is one of the machine learning methods. As a result of the Variation Inflation Factor Test, we selected and fitted the significant variable as temperature, precipitation, wind speed, wind direction, air pressure, dewpoint, hours of daylight and cloud cover. It was noted that the Hours of daylight, cloud cover and air pressure has high explained value in explonatory variable. The average coefficient of determination (R-Squared) of the Generalized Additive Model was 0.69. The constructed model can help to predict the influence on the external forces of electric pole, and contribute to the purpose of securing safety on utility pole.

• Toxicological Research
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• 제34권2호
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• pp.103-110
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• 2018

Environmental stimuli can lead to the excessive accumulation of reactive oxygen species (ROS), which is one of the risk factors for premature skin aging. Here, we investigated the protective effects of $7-MEGA^{TM}$ 500 (50% palmitoleic acid, 7-MEGA) against oxidative stress-induced cellular damage and its underlying therapeutic mechanisms in the HaCaT human skin keratinocyte cell line (HaCaT cells). Our results showed that treatment with 7-MEGA prior to hydrogen peroxide ($H_2O_2$)-induced damage significantly increased the viability of HaCaT cells. 7-MEGA effectively attenuated generation of $H_2O_2$-induced reactive oxygen species (ROS), and inhibited $H_2O_2$-induced inflammatory factors, such as prostaglandin $E_2$ ($PGE_2$), tumor necrosis $factor-{\alpha}$ ($TNF-{\alpha}$), and $interleukin-1{\beta}$ ($IL-1{\beta}$). In addition, cells treated with 7-MEGA exhibited significantly decreased expression of matrix metalloproteinase-1 (MMP-1) and increased expression of procollagen type 1 (PCOL1) and Elastin against oxidative stress by $H_2O_2$. Interestingly, these protective activities of 7-MEGA were similar in scope and of a higher magnitude than those seen with 98.5% palmitoleic acid (PA) obtained from Sigma when given at the same concentration (100 nL/mL). According to our data, 7-MEGA is able to protect HaCaT cells from $H_2O_2$-induced damage through inhibiting cellular oxidative stress and inflammation. Moreover, 7-MEGA may affect skin elasticity maintenance and improve skin wrinkles. These findings indicate that 7-MEGA may be useful as a food supplement for skin health.

• Journal of Distribution Science
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• 제13권11호
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• pp.39-46
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• 2015

Purpose - In Korea, there has been a recent trend that shows housing prices have risen rapidly following the International Monetary Fund crisis. The rapid rise in housing prices is spreading recognition of this as a factor in housing price volatility. In addition, this raises the expectations of housing prices in the future. These expectations are based on the assumption that a relationship exists between the current housing prices and expected housing prices in the real estate industry. By performing an empirical analysis on the validity of the claim that an increase in current housing prices can be correlated with expected housing prices, this study examines whether a long-term equilibrium relationship exists between expected housing prices and existing housing prices. If such a relationship exists, the recovery of equilibrium from disequilibrium is analyzed to derive related implications. Research design, data, and methodology - The relationship between current housing prices and expected housing prices was analyzed empirically using the Vector Error Correction Model. This model was applied to the co-integration test, the long-term equilibrium equation among variables, and the causality test. The housing prices used in the analysis were based on the National Housing Price Trend Survey released by Kookmin Bank. Additionally, the Index of Industrial Product and the Consumer Price Index were also used and were obtained from the Bank of Korea ECOS. The monthly data analyzed were from January 1987 to May 2015. Results - First, a long-term equilibrium relationship was established as one co-integration between current housing price distribution and expected housing prices. Second, the sign of the long-term equilibrium relationship variable was consistent with the theoretical sign, with the elasticity of housing price distribution to expected housing price, the industrial production, and the consumer price volatility revealed as 1.600, 0.104,and 0.092, respectively. This implies that the long-term effect of expected housing price volatility on housing price distribution is more significant than that of the industrial production and consumer price volatility. Third, the sign of the coefficient of the error correction term coincided with the theoretical sign. The absolute value of the coefficient of the correction term in the industrial production equation was 0.006, significantly larger than the coefficients for the expected housing price and the consumer price equation. In case of divergence from the long-term equilibrium relationship, the state of equilibrium will be restored through changes in the interest rate. Fourth, housing-price volatility was found to be causal to expected housing price, and was shown to be bi-directionally causal to industrial production. Conclusions - Based on the finding of this study, it is required to relieve the association between current housing price distribution and expected housing price by using property taxes and the loan-to-value policy to stabilize the housing market. Further, the relationship between housing price distribution and expected housing price can be examined and tested using a sophisticated methodology and policy variables.

• Journal of the Society of Cosmetic Scientists of Korea
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• 제33권4호
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• pp.245-249
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• 2007

The alternation of extracellular matrix (ECM) protein in aging process is associated with symptoms such as wrinkling and loss of elasticity in skin. Now, the major target proteins for anti-aging have been metalloproteases and the structural proteins such as collagen and elastin. Recently, the interaction of cell and ECM proteins (collagen, fibrillin, and fibronectin) is reported to have an important role in survival, proliferation and tissue reconstruction. Fibronectin is a matrix adhesion protein which binds to collagen and integrin and degraded by serine proteases. It has been reported that fragments of fibronectin (Fn-fr's) were involved in matrix metalloproteases (MMPs) expression in osteoblast. But, the role of Fn-fr's in human skin and in skin cells has not been reported yet. Therefore, we investigated the differences of fibronectin fragmentation pattern between young and aged human skin, and demonstrated that the fragmentation of fibronectins is significantly increased in aged human skin. Also, treatment of Fn-fr's (70, 45 kDa) increased MMP-1 expression and MMP-2 activity in human dermal fibroblasts. Our results suggest that Fn-fr's as a potential new factor to accelerate skin aging.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• 제14권1호
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• pp.74-80
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• 2011

Purpose: Based on previous research findings, it is well-known that the timing of surgery is generally considered the most important prognostic factor for a Kasai portoenterostomy, the primary treatment for biliary atresia. This research aimed to identify the optimal timing of a Kasai portoenterostomy and to verify if the proposed optimal timing corresponds to previous studies. All patients were classified by the timing of surgery, and pre- and post-operative fibrotic changes of the liver were measured with the elasticity value from fibroscans. Methods: The stiffness scores of the pre- and post-operative fibroscans in 34 patients who were treated by Kasai portoenterostomy from October 2007 to September 2010 in Severance children's hospital were reviewed. Results: The earlier the patients were treated by Kasai portoenterostomy, the lower the fibroscan scores. When the patients were treated prior to the 8th week, the post-operative scores of the fibroscans were significantly better than those patients who were treated after the 8th week, and some even recovered partially. Moreover, when operated before the 8th week, the differences between each pre- and postoperative fibroscan score also showed statistical relevance (p=0.0002). Conclusion: The earlier the patient was treated by Kasai portoenterostomy, the less liver fibrosis that developed, the lower the level of post-operative fibrosis, and the less the degree of fibrotic progress before and after the operation. Thus, this research proposal reconfirms once more that the 8th week is the optimal timing for a Kasai portoenterostomy.