• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.60.2-60.2
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• 2011

This study is to develop a 1kW-class small wind turbine blade which will be applicable to relatively low speed regions. For this blade, a high efficiency wind turbine blade is designed and a light and low cost composite structure blade is adopted considering fatigue life. In this study, shape design of 1kW-class small wind turbine blade for hybrid power generation system is carried out by BEMT(blade element momentum theory). X-FOIL open software was used to acquire lift and drag coefficients of the 2D airfoils used in power prediction procedure. Moreover, pressure and velocity distributions are investigated according to TSR by CFD analysis.

• Proceedings of the KIPE Conference
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• 2004.07b
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• pp.696-699
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• 2004

This paper proposes the Low Cost Class-E Converter with Power Conversion Operation of Piezoelectric Transformer. The Power Piezoelectric transformer capacity used in the proposed circuit is 15W and the electric equivalent circuit is presented. Class E type converter has some merits such as small component count, small size, and low cost. The topology has also ZVS conditions for main switch, thus in efficiency aspect, it is also competitive for commercial feasibility. The analysis and design guideline are suggested and also they are verified by experimental results.

• Korean Journal of Mathematics
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• v.21 no.4
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• pp.365-374
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• 2013

Let $k=\mathbb{F}_q(T)$ be a rational function field over the finite field $\mathbb{F}_q$, where q is a power of an odd prime number, and $\mathbb{A}=\mathbb{F}_q[T]$. Let ${\gamma}$ be a generator of $\mathbb{F}^*_q$. Let $\mathcal{H}_n$ be the subset of $\mathbb{A}$ consisting of monic square-free polynomials of degree n. In this paper we obtain an asymptotic formula for the mean value of $L(1,{\chi}_{\gamma}{\small{D}})$ and calculate the average value of the ideal class number $h_{\gamma}\small{D}$ when the average is taken over $D{\in}\mathcal{H}_{2g+2}$.

• Journal of the Korean Institute of Rural Architecture
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• v.13 no.2
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• pp.47-54
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• 2011

According to the master plan of the Ministry of Education, Science and Technology, departmentalized class system will be extended to all general middle & high schools by 2014 with the exception only of those having less than 6 classes located in small cities in rural areas. Under departmentalized class system, according to class timetable, students need to move from classroom to another classroom and areas where homebases, lounges, media spaces, rest places, and etc. This study has been undertaken to provide architectural data required in planning for student & learning support space for schools operating departmentalized class system, by investigating and analyzing cases in use at schools operating the system in Chungbuk area. As departmentalized class system is increasingly introduced, student & learning support space should be understood newly as spaces indispensable for students.

• Journal of the Korean Statistical Society
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• v.33 no.3
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• pp.323-337
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• 2004

This article coined a general class of estimators for various measures in normal population when some' a priori' or guessed value of standard deviation a is available in addition to sample information. The class of estimators is primarily defined for a function of standard deviation. An unbiased estimator and the minimum mean squared error estimator are worked out and the suggested class of estimators is compared with these classical estimators. Numerical computations in terms of percent relative efficiency and absolute relative bias established the merits of the proposed class of estimators especially for small samples. Simulation study confirms the excellence of the proposed class of estimators. The beauty of this article lies in estimation of various measures like standard deviation, variance, Fisher information, precision of sample mean, process capability index $C_{p}$, fourth moment about mean, mean deviation about mean etc. as particular cases of the proposed class of estimators.

• Journal of Information Processing Systems
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• v.13 no.5
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• pp.1345-1357
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• 2017

A prototype selection method chooses a small set of training points from a whole set of class data. As the data size increases, the selected prototypes play a significant role in covering class regions and learning a discriminate rule. This paper discusses the methods for selecting prototypes in a classification framework. We formulate a prototype selection problem into a set covering optimization problem in which the sets are composed with distance metric and predefined classes. The formulation of our problem makes us draw attention only to prototypes per class, not considering the other class points. A training point becomes a prototype by checking the number of neighbors and whether it is preselected. In this setting, we propose a greedy algorithm which chooses the most relevant points for preserving the class dominant regions. The proposed method is simple to implement, does not have parameters to adapt, and achieves better or comparable results on both artificial and real-world problems.

• Journal of Educational Research in Mathematics
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• v.10 no.2
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• pp.229-246
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• 2000

The purpose of this paper is to compare and analyze the two different teaching methods of elementary mathematics in the traditional method and in the constructive view. To do so, the actual class in the constructive view has been made for about four months using a class of 45 students in the second grade of an elementary school. After the class was finished, we collected diverse data from the class, such as the responses from the children(self-evaluation, mathematics diary, observation by the investigator, daily report), class evaluation report by other teacher and so on. The results of this research are as follows: First, the traditional class reaches at the goal of learning in a unit time because the class is guided by the teacher but the class in the constructive view is a little flexible because it is contextual. Second, in the constructive process of mathematical knowledge we knew that small group activities or discussion without intervention of teacher was often ended in exhaustive argument without arriving at valid social consensus. Third, the attitude in mathematics was changed from the passive one to the self-regulated ones. Fourth, the class in the constructive view could extend not only the ability of mathematical communication but also the ability of self-directed learning of children. Fifth, it was a considerable change the role of teacher, that is, guide of instruction instead of unique specialist in the classroom. Sixth, finally, the evaluation was made after finishing a unit class in the traditional instruction but it was integrated in a class in a constructive view.

• The korean journal of orthodontics
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• v.42 no.2
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• pp.80-86
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• 2012

Objective: This study aimed to investigate the current data regarding age, sex, and Angle Classification of Korean orthodontic patients and influence of these factors on the tendency to undergo extraction and orthognathic surgery. Methods: The recent trends of Korean orthodontic patients were assessed using questionnaire survey. The questionnaires were e-mailed to orthodontists who met the study criteria; 58% of the orthodontists opened the e-mails, and 27.7% replied to the e-mails. In all, the medical records of 11,340 patients who underwent orthodontic treatment at private clinics and small dental hospitals in Korea were analyzed. Results: The percentage of female patients in the study sample was 69.6%, and the average age of the patients was 19.87 years. The percentage of patients who were older than 19 years was 50.2%. Class II and Class III malocclusions were noted in 33.6% and 23.6% of patients, respectively. Extraction and orthognathic surgery were performed in 60.4% and 6.9% of patients, respectively. Conclusions: The results showed that there were a high percentage of adult, Class II malocclusion and extraction patients in private practices and small dental hospitals during the study period. Further, a relatively high proportion of adult patients opted to undergo orthognathic surgery.

• Journal of the Korean Institute of Rural Architecture
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• v.21 no.1
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• pp.9-16
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• 2019

The decrease in population of school age is one of major influencing factor of transformative educational environment. After the nineteen eighties, the population of South Korea has increased step by step, but the population of school age has been decreasing rapidly by low birth rate. As a result, closed school by merger and abolition of small school occurred all over the country. The closed school needed effective function as center of local community. Consequently the purpose of this study is to provide basic data for effective policy making of closed school by comparative analysis of educational environment such as number of students, schools, students per class, status of usage of closed school of the east area and the west area divided by The Tae Baek Mountains in the Gangwon-do, which has the least students in the nationwide. The results of this study are summarized as follows: 1) Gangwon-do has high decreasing rate of population, schools and students compared with other provinces. However it has significantly low number of students per class. 2) The number of students, schools of the west area in Gangwon-do outnumbers that of the east area. However the number of students per class of the east area in Gangwon-do lesser than that of the west area.

• Smart Media Journal
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• v.8 no.2
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• pp.46-57
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• 2019

In recent research, deep learning-based methods have achieved state-of-the-art performance in various computer vision tasks. However, these methods are commonly supervised, and require huge amounts of annotated data to train. Acquisition of data demands an additional costly effort, particularly for the tasks where it becomes challenging to obtain large amounts of data considering the time constraints and the requirement of professional human diligence. In this paper, we present a data level synthetic sampling solution to learn from small and imbalanced data sets using Generative Adversarial Networks (GANs). The reason for using GANs are the challenges posed in various fields to manage with the small datasets and fluctuating amounts of samples per class. As a result, we present an approach that can improve learning with respect to data distributions, reducing the partiality introduced by class imbalance and hence shifting the classification decision boundary towards more accurate results. Our novel method is demonstrated on a small dataset of 2789 tomato plant disease images, highly corrupted with class imbalance in 9 disease categories. Moreover, we evaluate our results in terms of different metrics and compare the quality of these results for distinct classes.