• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.9
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• pp.418-424
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• 2017

Magnesium has a higher specific strength than other metals and is widely used industry wide due to its excellent vibration absorption ability and electromagnetic wave shielding property.For example, it is used for automobile parts such as car seat frames and cylinder heads, and is widely used in electronic products such as notebook cases and mobile phone cases. In addition, it is in the spotlight as a bone-implant material used to assist in the treatment of damaged bones when the bones are cracked or broken. Currently, Ti alloy, stainless steel and Co-Cr-Mo alloy are used as the implant material, and the Mg alloy remains in research stage. The current problem with bone implant implants is that the patients must undergo reoperation to remove the implants after joint surgery. Magnesium, however, can achieve sufficient strength compared to current materials. In addition, since it is self-decomposed after the recovery, reoperation is not necessary. In this paper, Mg alloys were designed by adding harmless Ca and Zn to the human body. In order to improve the strength and corrosion resistance, the final alloy was designed by adding a small amount of Sr as a grain refiner. The radioactive elements of Sr are harmful to the human body, but other naturally occurring Sr elements are harmless. Microstructure analysis of the alloys was performed by optical microscopy and scanning electron microscopy. The mechanical properties and corrosion characteristics were evaluated by tensile test, potentiodynamic test and immersion test.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.9
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• pp.267-280
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• 2017

The purpose of this study is to provide cosmetic companies and research institutes with basic data regardingthe development of marketing by making out the influence and characteristics of consumption. A total of 506 questionnaires were used as analysis for the questionnaire survey of twenty female college students who purchased cosmetics within sixmonths in Seoul and the metropolitan area. Consumption propensity varied characteristics depending on the degree of makeup, average number of purchases, main reason for using cosmetics, and where to buy cosmetics. Motivation for purchasing cosmetics varied characteristics depending on the largest skin problem, the degree of usual makeup, the average number of times cosmetics were purchased, and the main reason forusing cosmetics. The results revealed thepropensities of saving resources, planned purchases, consciousness to others, and impulse buying have significant effects on the cosmetic purchase motives of product conversion, being others-oriented, economicsand pursuing beauty(P<0.05).Consequently, this study hopes to contribute to the development of cosmetics companies and research institutes by providingbasic data forfuture development of productsas well as formarketing strategiesusing customer psychology by referring to various perspectives ofconsumer direction and desired purchase behavior.

• The Korean Journal of Applied Statistics
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• v.29 no.7
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• pp.1459-1473
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• 2016

Both longitudinal data and survival data are collected simultaneously in longitudinal data which are observed throughout the passage of time. In this case, the effect of the independent variable becomes biased (provided that sole use of longitudinal data analysis does not consider the relation between both data used) if the missing that occurred in the longitudinal data is non-ignorable because it is caused by a correlation with the survival data. A joint model of longitudinal data and survival data was studied as a solution for such problem in order to obtain an unbiased result by considering the survival model for the cause of missing. In this paper, a joint model of the longitudinal zero-inflated count data and survival data is studied by replacing the longitudinal part with zero-inflated count data. A hurdle model and proportional hazards model were used for each longitudinal zero inflated count data and survival data; in addition, both sub-models were linked based on the assumption that the random effect of sub-models follow the multivariate normal distribution. We used the EM algorithm for the maximum likelihood estimator of parameters and estimated standard errors of parameters were calculated using the profile likelihood method. In simulation, we observed a better performance of the joint model in bias and coverage probability compared to the separate model.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.26 no.4
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• pp.1073-1084
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• 2016

The purpose of this study is to present the correct direction of research in related fields by analyzing the trends in the domestic study right to be forgotten. In this study, the final selection of 80 pieces of research papers in various disciplines to search for the study and were analyzed by setting the seven criteria and three research questions. Results, notice that significantly increase the amount of research around the social sciences, starting with the EU rules(draft) has been published in 2012, and around the problem navigating the Law oriented research actively done through a literature review and legal research methods can. Intensive study of the protected rights and the conflict in time towards the latter subject was also increased. The right to be forgotten when considering that big data, digital information such diverse and complex technical issues (service), which still lacks support the implementation of the rights ithil research is desperately needed to know the future with the realization that the scope and research methods. The purpose of this study is to present the research direction of the limits intended for domestic research, but realize effective right to be forgotten by future foreign comparative analysis.

• Korean Journal of Agricultural Science
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• v.41 no.4
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• pp.473-480
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• 2014

Upon setting up a dedicated plastic greenhouse for tomato cultivation developed by the Rural Development Administration on the Gyehwa reclaimed land, this study was aimed at analyzing the problems can be occurred in the installation of plastic greenhouse on reclaimed lands as well as finding out solutions for improvement. A relatively cheaper wooden pile was used in the installation in order to supplement the soft ground conditions. Based on the results of ground investigation of the installation site, both the allowable bearing capacity and pulling resistance of the wooden pile with a diameter of 150 mm and a length of 10 m were computed and came out to be 30.645 kN. It was determined that the values were enough to withstand the maximum compressive force (17.206 kN) and the pullout force (20.435 kN) that are generally applied to the greenhouse footing. There are three problems aroused in the process of greenhouse installation, and the corresponding countermeasures are as follow. First, due to the slightly bent shape of the wooden pile, there were phenomenon such as deviation, torsion, and fracture when driving the pile. This could be prevented by the use of the backhoe (0.2) rotating tongs, which are holding the pile, to drive the pile while pushing to the direction of the driving and fixing it until 5 m below ground and applying a soft vibrating pressure until the first 2 m. Second, there exists a concrete independent footing between the column of the greenhouse and the wooden pile driven to the underground water level. Since it is difficult to accurately drive the pile on this independent footing, the problem of footing baseplate used to fix the column being off the independent footing was occurred. In order to handle with this matter, the diameter of the independent footing was changed from 200 mm to 300 mm. Last, after films were covered in the condition that the reinforcing frame and bracing are not installed, there was a phenomenon of columns being pushed away by the strong wind to the maximum of $11m{\cdot}s^{-1}$. It is encouraged to avoid constructions in winter, and the film covering jobs always to be done after the frame construction is completely over. The height of the independent footing was measured for 9 months after the completion of the greenhouse installation, and it was found to be within the margin of error meaning that there was no subsidence. The extent to the framework distortion and the value of inclinometers as well showed not much alteration. In other words, the wooden pile was designed to have a sufficient bearing capacity.

• The Journal of the Korea Contents Association
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• v.15 no.7
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• pp.1-11
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• 2015

In recent high performance computing system, GPGPU has been widely used to process general-purpose applications as well as graphics applications, since GPU can provide optimized computational resources for massive parallel processing. Unfortunately, GPGPU doesn't exploit computational resources on GPU in executing general-purpose applications fully, because the applications cannot be optimized to GPU architecture. Therefore, we provide GPU research guideline to improve the performance of computing systems using GPGPU. To accomplish this, we analyze the negative factors on GPU performance. In this paper, in order to clearly classify the cause of the negative factors on GPU performance, GPU core status are defined into 5 status: fully active status, partial active status, idle status, memory stall status and GPU core stall status. All status except fully active status cause performance degradation. We evaluate the ratio of each GPU core status depending on the characteristics of benchmarks to find specific reasons which degrade the performance of GPU. According to our simulation results, partial active status, idle status, memory stall status and GPU core stall status are induced by computational resource underutilization problem, low parallelism, high memory requests, and structural hazard, respectively.

• Journal of the Korea Convergence Society
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• v.7 no.6
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• pp.249-258
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• 2016

In this research, we analyzed the research and development process of small and medium enterprises, and diagnosed the problem of the research and development process of domestic small and medium enterprises, and evaluated the influence of innovative ability on the speed of research and development and corporate performance. In evaluating these effects, it is possible to grasp the direction of power generation according to the type of analysis, taking into account the meltdown factor of factors related to innovative capabilities. The main purpose of this research is to confirm the influence on the speed of research and development according to the innovative capacity and business environment and to verify the reliability and validity of the research by Klumbach alpha Was used. In this research, we analyzed how the speed of R & D affects R & D activities, it is a research aimed at the necessity of a resource-based approach to the internal capacity of a company, Have a valuable value. Based on the influence on the company, each factor is a research that analyzed the influence on R & D and financial indicators through maintaining company's development level, Research that has practical value that can base on the development of R & D capacity on corporate strategy formulation.

• Advances in aircraft and spacecraft science
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• v.5 no.2
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• pp.225-237
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• 2018

The difficulties of satellite vibration testing are due to the commonly expressed qualification requirements being incompatible with the limited performance of the entire controlled system (satellite + interface + shaker + controller). Two features cause the problem: firstly, the main satellite modes (i.e., the first structural mode and the high and low tank modes) are very weakly damped; secondly, the controller is just too basic to achieve the expected performance in such cases. The combination of these two issues results in oscillations around the notching levels and high amplitude beating immediately after the mode. The beating overshoots are a major risk source because they can result in the test being aborted if the qualification upper limit is exceeded. Although the abort is, in itself, a safety measure protecting the tested satellite, it increases the risk of structural fatigue, firstly because the abort threshold has been already reached, and secondly, because the test must restart at the same close-resonance frequency and remain there until the qualification level is reached and the sweep frequency can continue. The beat minimum relates only to small successive frequency ranges in which the qualification level is not reached. Although they are less problematic because they do not cause an inadvertent test shutdown, such situations inevitably result in waiver requests from the client. A controlled-system analysis indicates an operating principle that cannot provide sufficient stability: the drive calculation (which controls the process) simply multiplies the frequency reference (usually called cola) and a function of the following setpoint, the ratio between the amplitude already reached and the previous setpoint, and the compression factor. This function value changes at each cola interval, but it never takes into account the sensor signal phase. Because of these limitations, we firstly examined whether it was possible to empirically determine, using a series of tests with a very simple dummy, a controller setting process that significantly improves the results. As the attempt failed, we have performed simulations seeking an optimum adjustment by finding the Least Mean Square of the difference between the reference and response signal. The simulations showed a significant improvement during the notch beat and a small reduction in the beat amplitude. However, the small improvement in this process was not useful because it highlighted the need to change the reference at each cola interval, sometimes with instructions almost twice the qualification level. Another uncertainty regarding the consequences of such an approach involves the impact of differences between the estimated model (used in the simulation) and the actual system. As limitations in the current controller were identified in different approaches, we considered the feasibility of a new controller that takes into account an estimated single-input multi-output (SIMO) model. Its parameters were estimated from a very low-level throughput. Against this backdrop, we analyzed the feasibility of an LQG control in cancelling beating, and this article highlights the relevance of such an approach.

• Journal of the Korean School Mathematics Society
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• v.20 no.4
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• pp.521-536
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• 2017

One of difficulties with which teachers meet is to have underachievers with no willingness and motivation for study involved in class. Mathematics underachiever are average or above average in their intelligence but their actual achievement in mathematics did not coincide to their intellectual capabilities. The teaching strategy for them is to motivate them to try to study mathematics and to experience the improvement in their mathematics grade. In this paper, we choose flipped classroom as the strategy of teaching basic mathematics to math underachievers and applied it to them. Then we wanted to make sure the possibility for applying flipped classroom to teaching math underachievers through the analysis of change in the scholastic achievement of students in mathematics and mathematical disposition. The results of this study are as followings; First, when we taught basic math to underachievers using a flipped classroom, we confirm that math underachievers with active participation improved scholastic achievements significantly. Second, the flipped classroom was led to positive effects in an affective domain. In particular, it showed the most noticeable change in the area of willingness to math problem-solving and perception about the value of mathematics.

• Journal of The Korean Society of Grassland and Forage Science
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• v.38 no.2
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• pp.135-139
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• 2018

This study was conducted to evaluate the forage production and feed value of Sasa borealis (S. borealis) in Jeju Island in order to improve the utilization of Sasa borealis and to help mitigate the problem of reduced plant species diversity caused by S. borealis in Hanlla Mountain. To investigate the forage production, three quadrat structures were installed in the S. borealis natural community in the middle part of Hanlla Mountain. From May to October 2017, S. borealis in quadrats was cut at a fixed time of each month, and then forage production and regenerated acidity per kg/ha were evaluated. For the evaluation of feed value, compositional analysis was performed on the monthly samples. In vitro digestion experiments were carried out using cannula mounted Hanwoo. In vitro neutral detergent fiber digestibility(IVNDFD) and in vitro acid detergent fiber digestibility(IVADFD) were measured after the experiment. Forage production of S. borealis showed relatively good regeneration ability in May and June, but the regeneration ability decreased as the cutting was repeated. In order to use S. borealis as a forage, it is considered efficient to feed black goats with good fiber decomposition or horses good palatability to S. borealis and relatively good digestibility.