• International Journal of Aeronautical and Space Sciences
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• 제11권3호
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• pp.227-233
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• 2010

In this study, a genetic algorithm was utilized to optimize the stacking sequence of a composite plate subjected to a high velocity impact. The aim is to minimize the maximum backplane displacement of the plate. In the finite element model, we idealized the impactor using solid elements and modeled the composite plate by shell elements to reduce the analysis time. Various tests were carried out to investigate the effect of parameters in the genetic algorithm such as the type of variables, population size, number of discrete variables, and mutation probability.

• Journal of Nutrition and Health
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• 제24권4호
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• pp.378-392
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• 1991

A series of studies in monkeys and hamsters, and reevaluation of published human data, indicate that dietary saturated fatty acids exert a dissimilar metabolic impact on cholesterol metabolism. Myristic acid(14 : 0) appears to have a major cholesterol-raising effect by means of decreasing LDL receptor activity and by increasing the direct production of LDL (from sources other than VLDL-catabolism) Palmitic acid (16 : 0) appears neutral in most cases (plasma cholesterol<200mg/dl) or until the LDL receptor is down-regulated, as with high cholesterol intake or obesity. In such cases. the down-regulated LDL receptors coupled with an increased VLDL production (induced by 16 : 0 and 18 : 1) can divert VLDL remnants to LDL and expand the LDL pool. Furthermore. the cholesterolemic impact of any saturated fatty acid can be countered up to a saturable 'threshold' level by dietary linoleic acid (18 : 2) which up-regulates the LDL receptor. Once above this 'threshold' the major fatty acids (16 : 0, 18 : 0, 18 : 1, 18 : 2, 18 : 3) appear to exert an equal impact on the circulating cholesterol concentration.

• Bulletin of the Korean Chemical Society
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• 제26권3호
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• pp.399-408
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• 2005

We have utilized neural network (NN) studies to predict impact sensitivities of various types of explosive molecules. Two hundreds and thirty four explosive molecules have been taken from a single database, and thirty nine molecular descriptors were computed for each explosive molecule. Optimization of NN architecture has been carried out by examining seven different sets of molecular descriptors and varying the number of hidden neurons. For the optimized NN architecture, we have utilized 17 molecular descriptors which were composed of compositional and topological descriptors in an input layer, and 2 hidden neurons in a hidden layer.

• The Journal of Asian Finance, Economics and Business
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• 제1권3호
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• pp.29-36
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• 2014

This paper attempts to measure the impact of non-financial factors including analyst practices and broker resources on performance of sell side research. Results reveal that these non-financial factors have a measurable impact on performance of target price forecasts. Number of pages written by an analyst (surrogate for analyst practice) is significantly and directly linked with target price accuracy indicating a more elaborate analyst produces better target price forecasts. Analyst compensation (surrogate for broker resource) is significantly and inversely linked with target price accuracy. Out performance by analysts working with lower paying firms is possibly associated with motivation to migrate to higher paying broking firms. The study finds that employing more number of analysts per research report has no significant impact on target price accuracy -negative coefficient indicates that team work may not result in better target price forecasts. Though insignificant, long term forecast horizon negatively affects target price accuracy while stock volatility improves target price accuracy.

• Journal of Information Science Theory and Practice
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• 제2권1호
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• pp.22-34
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• 2014

This paper analyzes India's contribution to world tribology research during the period 2001-2012 based on SCOPUS records. India's global publication share, annual output, and its citation impact of Indian contribution, partner countries, leading contributors, leading institutes, and highly cited papers were analyzed. Additionally, a cloud technique is used to map frequently used single words in titles. It is observed that India ranks in the $7^{th}$ position with a global publication share of 3.83% and an annual average growth rate of 25.58% during the period 2001-2012. The citation impact of India's contribution is 6.05 which decreased from 12.74 during 2001-2006 to 4.62 during 2007-2012. 17.4% of India's total research output was published with international collaboration.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 한국방사성폐기물학회 2017년도 춘계학술논문요약집
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• pp.155-156
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• 2017

In this study, the structural integrity of the spent nuclear fuel assemblies was evaluated by carrying out a 0.3 m drop impact analysis, one of the normal transportation conditions of the nuclear fuel assemblies. For this purpose, the spent nuclear fuel assembly was modeled in detail as beam elements, and a coupled model for impact analysis was developed by inserting the modeled nuclear fuel assemblies into a cask.

• Journal of Adhesion and Interface
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• 제16권3호
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• pp.101-107
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• 2015

Epoxy resin toughening agents such as core/shell nanoparticles, CTBN epoxy, polyester polyols, and polyurethane have been widely used in order to compensate for the brittleness and improve the impact resistance of the epoxy resin. In this work, a few tougheners mentioned above were individually added into adhesive compositions to observe the effects of physical and mechanical properties. Both flexural strength and flexural modulus were measured with UTM while impact strength was analyzed with Izod impact tester. The obtained results showed that the addition of toughening agents afforded positive performance in terms of flexibility and impact resistance of the cured epoxy resin. Furthermore, DMA experiments suggested that the trends of storage modulus data of each epoxy resin composition coincided with the trends of flexural modulus data. FE-SEM images showed that toughening agents formed circled-shape particles when it was cured in epoxy resin composition at high temperature by phase separation. The existence of particles in the cured samples explains why epoxy resin with toughener has higher impact resistance.

• Korean Journal of Materials Research
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• 제28권8호
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• pp.478-488
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• 2018

In this study, three kinds of steels are manufactured by varying the rolling conditions, and their microstructures are analyzed. Tensile and Charpy impact tests are performed at room temperature to investigate the correlation between microstructure and mechanical properties. In addition, heat affected zone(HAZ) specimens are fabricated through the simulation of the welding process, and the HAZ microstructure is analyzed. The Charpy impact test of the HAZ specimens is performed at $-40^{\circ}C$ to investigate the low temperature HAZ toughness. The main microstructures of steels are quasi-polygonal ferrite and pearlite with fine grains. Because coarse granular bainite forms with an increasing finish rolling temperature, the strength decreases and elongation increases. In the steel with the lowest reduction ratio, coarse granular bainite forms. In the HAZ specimens, fine acicular ferrites are the main features of the microstructure. The volume fraction of coarse bainitic ferrite and granular bainite increases with an increasing finish rolling temperature. The Charpy impact energy at $-40^{\circ}C$ decreases with an increasing volume fraction of bainitic ferrite and granular bainite. In the HAZ specimen with the lowest reduction ratio, coarse bainitic ferrite and granular bainite forms and the Charpy impact energy at $-40^{\circ}C$ is the lowest.

• Atmosphere
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• 제30권1호
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• pp.47-57
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• 2020

In this study, the climatological spatio-temporal variation of strong wind and gust wind in Korea during the period from 1993 to 2018 was analyzed using daily maximum wind speed and daily maximum instantaneous wind speed data recorded at 61 observations. Strong wind and gust wind were defined as 14 m s^-1 and 20 m s^-1, which are the same as the KMA's criteria of special weather report. The frequency of strong wind and gust wind occurrence was divided into regions with the higher 25 percent (Group A) and the lower 75 percent (Group B). The annual frequency of strong wind and gust wind occurrence tended to be decreased in most parts of the Korean peninsula. In Group A with stations located at coastal region, strong wind and gust wind occurred most frequently in winter with higher frequency at 1200~1600 LST and 2300~2400 LST due to influence of East Asian winter monsoon. In addition, a marked decreasing trend throughout the four seasons was shown at Daegwallyeong, Gunsan and Wando observations. In contrast, it can be found in Group B that the monthly frequency of strong wind and wind gust occurrence was higher in August and September by effect of typhoon and hourly frequency was higher from 1200 LST to 1800 LST.

• Journal of Environmental Impact Assessment
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• 제4권2호
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• pp.151-156
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• 1995

Public participation in Environmental Impact Assessment (EIA) process has been implemented since the introduction of EIA project on August 1 1991, followed with Environmental Policy Act promulgation on August 1 1990. Though public participation has room for improvement. This study compared before and after the introduction of public participation on EIS preparation cost, project cost, EIS preparation term and project term through 293 EISs analysis. Also public opinions in EIS after introduction of public participation were analyzed. The results are expected to be contributed to the system improvement of public participation.