• International Journal of Reliability and Applications
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• 제15권1호
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• pp.1-9
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• 2014

Let X and $X_t$ denote the lifetime and the residual life at age t, respectively. X is said to be a NBUL (new better than used in Laplace transform order) random variable if $X_t$ is smaller than X in Laplace order, i.e., $X_t{\leq}_{LT}X$. We propose a new test statistics for testing exponentiality versus NBUL class of life distribution. The tests by Hollender and Proschan (1975) and the generalized Hollender and Proschan test by Ains and Mitra (2011) are considered as special cases of the our of test statistics. Our proposed test statistics is simple, consistent and asymptotically normal. Efficiency and powers of the test statistics for some commonly used distributions in reliability are discussed. Finally, real examples are presented to illustrate the theoretical results.

• 대한수학회보
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• 제59권1호
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• pp.141-154
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• 2022

Let R be a commutative ring with identity. Denote by w𝒫_w the class of weak w-projective R-modules and by w𝒫_w^⊥ the right orthogonal complement of w𝒫_w. It is shown that (w𝒫_w, w𝒫_w^⊥) is a hereditary and complete cotorsion theory, and so every R-module has a special weak w-projective precover. We also give some necessary and sufficient conditions for weak w-projective modules to be w-projective. Finally it is shown that when we discuss the existence of a weak w-projective cover of a module, it is enough to consider the w-envelope of the module.

• 한국초등과학교육학회지:초등과학교육
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• 제33권1호
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• pp.95-104
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• 2014

The purpose of this study is to analyze the state of science teaching anxiety of elementary teachers for the scientifically gifted according to their personal variables such as gender, career in education and gifted education, training course for gifted education, participation in meeting related to gifted education. The subjects in this study were 64 elementary school teachers who were in charge of science gifted education. The instrument to assess their science teaching anxiety was Westerback's S-STAI, modified in this study to be suitable for science gifted education. The collected data were analyzed by the statistical package SPSS. The findings of the study were as follows: The teachers for gifted felt more teaching anxiety in gifted classes than in normal classes on the whole. There were statistically significant differences in their personal variables such as gender, career in education experience, experience of taking gifted education training courses, and participation in meeting related to gifted education. Implications related to reduce the gifted education teachers' teaching anxiety were discussed in depth.

• 대한수학회지
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• 제45권6호
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• pp.1725-1740
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• 2008

In this paper, we introduce a fixed point index of weakly inward 1-set-contraction mappings. With the aid of the new index, we obtain some new fixed point theorems, nonzero fixed point theorems and multiple positive fixed points for this class of mappings. As an application of nonzero fixed point theorems, we discuss an eigenvalue problem.

• 대한지구과학교육학회지
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• 제7권1호
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• pp.34-42
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• 2014

The purpose of this study was to examine the effects on the effects of science lessons using six thinking hats techniques on creativity and science academic achievement. To verify the research problem, the subject of this study was fourth-grade students selected from four classes of an elementary school located in Busan. For ten weeks, the experimental group of 40 students was taught using the six thinking hats techniques. The comparative group also of 40 students, was taught in normal classes which used a Text-book. Children were given a creativity test and academic achievement test in science to measure the effects on six thinking hats techniques. Likert scales were used to gather students feedbacks on creativity and science academic achievement. Through these procedures, the following results were obtained: First, the six thinking hats techniques had a more effect on creativity than the normal classes, where a text-book was used. Second, the six thinking hats techniques could be seen to be effective in improving the student's academic achievements in science than the normal classes which used a Text-book. Third, the result of the student recognition investigation, we could know that the students showed lots of interest in the science lessons using six thinking hats techniques, and they were able to understand the scientific theories. As a result, the elementary science class with six thinking hats techniques had the effects of developing creativity and science academic achievement. It means the science class with six thinking hats techniques has potential possibilities and value to develop creativity and science academic achievement.

• 한국융합학회논문지
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• 제9권6호
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• pp.33-38
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• 2018

본 논문에서는 단일 클래스만을 학습하여 차량에 대한 새로운 공격을 탐지한다. 분류 성능 평가를 위해 Car-Hacking 데이터셋을 사용한다. Car-Hacking 데이터셋은 실제 차량의 OBD-II 포트를 통해 CAN (Controller Area Network) 트래픽을 로깅하여 생성된다. 이 데이터셋에는 네 가지 공격 유형이 포함된다. 실험에 사용한 단일 클래스 분류기법은 정상 클래스만을 학습하여 비정상인 공격 클래스를 분류해내는 비지도 학습이다. 비지도 학습 방법을 사용하는 경우에 훈련 과정에서 네거티브 인스턴스를 사용하지 않기 때문에 고효율의 분류 성능을 내는 것은 어렵다. 하지만, 비지도 학습은 라벨이 없는 새로운 공격 데이터를 분류하는데 적합한 장점이 있다. 본 연구에서는 네트워크 침입탐지 시스템에서 서명기반의 규칙으로 탐지하기 어려운 새로운 공격 유형을 탐지하기 위해 단일 클래스 분류기를 사용한다. 제안 방법은 새로운 공격을 모두 탐지하고 정상데이터에 대해서도 효율적인 분류 성능을 보이는 파라미터 조합을 제시한다.

• 대한치과교정학회지
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• 제43권5호
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• pp.209-217
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• 2013

Objective: This study investigated whether temporomandibular joint (TMJ) condyle-fossa relationships are bilaterally symmetric in class III malocclusion patients with and without asymmetry and compared to those with normal occlusion. The hypothesis was a difference in condyle-fossa relationships exists in asymmetric patients. Methods: Group 1 comprised 40 Korean normal occlusion subjects. Groups 2 and 3 comprised patients diagnosed with skeletal class III malocclusion, who were grouped according to the presence of mandibular asymmetry: Group 2 included symmetric mandibles, while group 3 included asymmetric mandibles. Pretreatment three-dimensional cone-beam computed tomography (3D CBCT) images were obtained. Right- and left-sided TMJ spaces in groups 1 and 2 or deviated and non-deviated sides in group 3 were evaluated, and the axial condylar angle was compared. Results: The TMJ spaces demonstrated no significant bilateral differences in any group. Only group 3 had slightly narrower superior spaces (p < 0.001). The axial condylar angles between group 1 and 2 were not significant. However, group 3 showed a statistically significant bilateral difference (p < 0.001); toward the deviated side, the axial condylar angle was steeper. Conclusions: Even in the asymmetric group, the TMJ spaces were similar between deviated and non-deviated sides, indicating a bilateral condyle-fossa relationship in patients with asymmetry that may be as symmetrical as that in patients with symmetry. However, the axial condylar angle had bilateral differences only in asymmetric groups. The mean TMJ space value and the bilateral difference may be used for evaluating condyle-fossa relationships with CBCT.

• Journal of applied mathematics & informatics
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• 제17권1_2_3호
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• pp.351-360
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• 2005

This paper finds a new class of generalized convex function which satisfies the following properties: It's level set is $\eta$-convex set; Every feasible Kuhn-Tucker point is a global minimum; If Slater's constraint qualification holds, then every minimum point is Kuhn-Tucker point; Weak duality and strong duality hold between primal problem and it's Mond-Weir dual problem.

• 대한수학회보
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• 제54권2호
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• pp.399-416
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• 2017

In this paper, we study a class of Finsler metrics called general (${\alpha},{\beta}$)-metrics, which are defined by a Riemannian metric ${\alpha}$ and a 1-form ${\beta}$. We show that every general (${\alpha},{\beta}$)-metric with isotropic Berwald curvature is either a Berwald metric or a Randers metric. Moreover, a lot of new isotropic Berwald general (${\alpha},{\beta}$)-metrics are constructed explicitly.

• 대한수학회보
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• 제54권4호
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• pp.1293-1307
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• 2017

General (${\alpha},{\beta}$)-metrics form a rich class of Finsler metrics. They include many important Finsler metrics, such as Randers metrics, square metrics and spherically symmetric metrics. In this paper, we find equations which are necessary and sufficient conditions for such Finsler metric to be locally projectively flat. By solving these equations, we obtain all of locally projectively flat general (${\alpha},{\beta}$)-metrics under certain condition. Finally, we manufacture explicitly new locally projectively flat Finsler metrics.