• 한국수학교육학회지시리즈E:수학교육논문집
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• 제35권4호
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• pp.413-423
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• 2021

수학적 대상 중 하나인 공집합에 대하여 고찰해본다. 공집합과 관련된 학생들의 다양한 오개념과 그 원인을 살펴보고 역사적 공집합의 도입배경과 이와 관련된 집합론의 공리계를 살펴본다. 순수한 개념적 대상인 공집합을 통하여 수학적 대상의 속성을 알아보고, 공리적 집합론에 기반하였다고 알려진 현대 철학자 알랭 바디우(Alian Badiou)의 존재론을 살펴본다. 이상의 논의를 바탕으로 연립방정식의 해와 해집합을 집합을 통해 설명하고 이와 관련하여 공집합의 존재성이 갖는 의미를 고찰하여본다. 이러한 관점으로 집합적 사고를 재해석해보고, 수학의 공리적 철학적 측면이 갖는 의의를 제시한다.

• Journal of applied mathematics & informatics
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• 제19권1_2호
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• pp.93-104
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• 2005

The present article discusses the number of empty convex 4-gons and empty convex 5-gons in a finite planar point set. New proofs are provided for the two related important results.

• 대한수학회지
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• 제59권2호
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• pp.337-352
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• 2022

We consider the set of points with historic behavior (which is also called the irregular set) for continuous flows and suspension flows. In this paper under the hypothesis that (X_t)_t is a continuous flow on a d-dimensional Riemaniann closed manifold M (d ≥ 2) with gluing orbit property, we prove that the set of points with historic behavior in a compact and invariant subset ∆ of M is either empty or is a Baire residual subset on ∆. We also prove that the set of points with historic behavior of a suspension flows over a homeomorphism satisfyng the gluing orbit property is either empty or Baire residual and carries full topological entropy.

• Journal of Mechanical Science and Technology
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• 제16권6호
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• pp.776-784
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• 2002

We have performed experimental studies for the improvements of pneumatic brake systems of freight trains. Currently, most of the freight trains operated by the Korean National Railroad have either empty-load or diaphragm type brake systems. In this study, appropriate methods that the air pressure characteristics in both type of brake systems are in accordance with each other have been investigated. We have also performed running tests using a 30 car-train set to design optimum capacity of a quick release valve. The test results show that the quick release valve is considerably effective in shortening the release time of the diaphragm type brake system. In the case of a normal brake application, the diaphragm type brake system with the quick release valve reduces the release time to 34% of that of the system without the quick release valve. This release time is almost equivalent to that of the empty-load type brake system. Accordance of braking performance in different types of brake systems in a train set is expected to prevent wheel flats and to reduce maintenance costs.

• 대한건축학회논문집:계획계
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• 제34권6호
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• pp.127-134
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• 2018

The purpose of this study is to derive a model of urban regeneration business using idle facilities in the old city center. The scope of the study was set as empty houses and empty stores owned by private companies, and analyzed the 50 central city revitalization projects using idle facilities in 14 local cities in Japan. The results of this study are follows; First, as an urban regeneration strategy using idle facilities in the old town, it was a combination of other functions centering on commercial functions or introducing new functions required in the city center. Second, various financial supports have been provided to induce the utilization of idle facilities by the private sector, and different strategies have been implemented for businesses that need maintenance first. Third, based on the analysis results, it was possible to derive urban regeneration business model. Fourth, in order to operate smooth business, it is a need for an organization that is in charge of reviewing the consistency of upper-level planning and urban guiding functions such as urban revitalization plan, balance review of expenditure and revenues by cost subsidy and loan repayment, consultation among the business partners.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집B
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• pp.593-598
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• 2000

Experimental study is conducted to clarify the pneumatic characteristics of brake system for freight train. Empty-load and diaphragm brake systems are mainly installed in the freight trains owned by KNR(Korean National Railroad). Experimental train set is composed of sixteen freight train and one diesel locomotive that are now in use. From the experimental results, in case of commercial brake, empty-load brake system responds to the brake command more slowly than the diaphragm brake system. But, in case of release command, the response time of diaphragm brake system is shorter than that of empty-load one. In the emergency brake test, the decreasing rate of brake pipe pressure of tenth car is almost same that of decreasing rate of commercial brake service.

• Structural Engineering and Mechanics
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• 제74권4호
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• pp.559-565
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• 2020

This paper intends to progress models to accurately estimate the behavior of fresh concrete under vibration using artificial neural networks (ANNs). To this end, behavior of a full scale precast concrete mold was investigated numerically. Experimental study was carried out under vibration with the use of a computer-based data acquisition system. In this study measurements were taken at three points using two vibrators. Transducers were used to measure time-dependent lateral displacements at these points on mold while both mold is empty and full of fresh concrete. Modeling of empty and full mold was made using ANNs. Benefiting ANNs used in this study for modeling fresh concrete, mold design can be performed. For the modeling of ANNs: Experimental data were divided randomly into two parts such as training set and testing set. Training set was used for ANN's learning stage. And the remaining part was used for testing the ANNs. Finally, ANN modeling was compared with measured data. The comparisons show that the experimental data and ANN results are compatible.

• 충청수학회지
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• 제36권1호
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• pp.9-11
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• 2023

Intuitionistic Zermelo-Fraenkel (IZF) set theory is a set theory without the axiom of choice and the law of excluded middle (LEM). The weak excluded middle law (WEM) states that ¬𝜑∨¬¬𝜑 for any formula 𝜑. In IZF we show that LEM is equivalent to WEM plus the condition that any set not equal to the empty set has an element.

• Kyungpook Mathematical Journal
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• 제64권1호
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• pp.161-169
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• 2024

A semi-well ordered set is a partially ordered set in which every non-empty subset of it contains a least element or a greatest element. It is defined as an extension of the concept of well ordered sets. An attempt is made to identify the properties of a semi-well ordered set equipped with the order topology.

• 호남수학학술지
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• 제31권3호
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• pp.315-321
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• 2009

Erd$\"{o}$s posed the problem of determining the minimum number g(n) such that any set of g(n) points in general position in the plane contains an empty convex n-gon. In 1978, Harborth proved that g(5) = 10. We reprove the result in a geometric approach.