• 한국수학사학회지
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• 제31권2호
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• pp.73-91
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• 2018

This study begins with the awareness of problem that the education of mathematics teachers has failed to link the limit and the infinite set conceptually. Thus, this study analyzes the historical and reciprocal development of the limit and the infinite set, and discusses how to improve the education of these concepts and their relation based on the outcome of this analysis. The results of the study confirm that the infinite set is the historical tool of linking the limit and the real numbers. Also, the result shows that the premise of 'the component of the straight line is a point.' had the fundamental role in the construction of the real numbers as an arithmetical continuum and that the moral certainty of this premise would be obtained through a thought experiment using an infinite set. Based on these findings, several proposals have been made regarding the teacher education of awakening someone to the fact that 'the theoretical foundation of the limit is the real numbers, and it is required to introduce an infinite set for dealing with the real numbers.' in this study. In particular, by presenting one method of constructing the real numbers as an arithmetical continuum based on a thought experiment about the component of the straight line, this study opens up the possibility of an education that could get the limit values psychologically connected to the infinite set in overcoming the epistemological obstacle related to the continuum concept.

• Journal of Electrical Engineering and Technology
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• 제2권3호
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• pp.342-345
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• 2007

This paper presents an engineering approach to derive the optimum price levels of transacted power. In this paper, with the assumption that power import is possible through the system connection in Northeast Asia regions, the upper price limit of imported power deserving economic efficiency was derived with respect to the time and amount of power import. The proposed approach was demonstrated based on the data from the National Power Development Planning in 2004 with the WASP model.

• 기술사
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• 제38권1호
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• pp.52-54
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• 2005

Korean metropolises are choked by lack of green space to attain the limit of horizontal expansion. The alternative plan is trying total expansion that the green zone and road are made from the rest site by high-rise buildings. And high-rise building can solve indiscriminate development to attain the limit situation. The building of landmark can be the image of the nation and the pride of the citizen. The relaxing the height restriction of government can be whole nation's interests. Appearing high-rise building in overpopulated city is the subject of a generation and this trend cannot be avoided.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 1993년도 제1회 학술강연회논문집
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• pp.55-61
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• 1993

An experimental investigation was conducted in order to determine the flammability limit of the solid fuel ramjet using the backward facing step flow combustion of the plexiglass grain. In order to get the different step height ratio, the grain was drilled straight forward or stepwise. The Phoenics computer code was adopted in order to compare. the flow patterns of the some sample tests using a non-reacting cold turbulent flow model. The stepwise grain give some loading advantage; specially thin and long shape grain design.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1997년도 가을 학술발표회 논문집
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• pp.111-116
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• 1997

In this paper, the limit temperature for applying maturity method are discussed. 4 kinds of W/C in combination of 7kinds of curing temperature are selected as experimental parameters. According to the experimental results, high curing temperature and low W/C gain in strength rapidly. And maturity rule can be applied less than $30^{\cire}C$ in W/C of 30~60% in the conditions of this experiment.

• 한국ITS학회 논문지
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• 제10권1호
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• pp.16-26
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• 2011

가변속도제어(Variable Speed Limit ; VSL)는 교통상황에 따라 속도를 차등 제한하여 혼잡 또는 사고지점에 도달하기전 차량간, 차로간 속도편차를 감소시킴으로써 사고를 예방하고 총 지체를 최소화하기 위한 연속류 ITS기법 중 하나이다. 본 연구에서는 가변속도 제어시 연속류 기본구간의 동적교통류에 대한 수학적 분석결과를 기초로 가변속도제어 수행모형을 제시하고 효과분석을 수행하였다. 가변속도제어모형은 병목현상 발생시 상류부에 전파되는 충격파의 속도를 최소화 함으로써 지체를 감소시킬 수 있도록 graphical solution을 적용하여 제시한다. 또한 가변속도 제어시 해당 지점으로부터 하류부로 전파되는 충격파의 생성 및 움직임을 모형화 하여 재현하며 그 방법론으로는 Cell-Transmission Model 및 Supply-Demand Method를 적용하였다. 가변속도제어 적용에 따른 효과분석으로는 제어를 통한 지체감소의 효용성 및 안전도 측면에서 각 Cell별 속도 및 밀도의 표준편차의 개선정도를 살펴보았다. 향후 본 연구의 이론적 검증 및 분석 결과를 토대로 다양한 가변속도제어모형 및 운영방안을 개발할 수 있을 것으로 예상한다.

• Communications for Statistical Applications and Methods
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• 제10권2호
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• pp.497-505
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• 2003

Under normality assumption, the tolerance interval for a future observation is sometimes of great interest in statistics. In this paper, we state the influence function on the standard deviation $\sigma$, and use it to derive the influence function on tolerance limits. Simulation study shows that the two influence functions perform very well.

• 대한기계학회논문집A
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• 제26권3호
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• pp.576-585
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• 2002

A three-dimensional Lagrangian explicit time-integration finite element code for analyzing the dynamic impact phenomena was developed. It uses four node tetrahedral elements. In order to consider the effects of strain rate hardening, strain hardening and thermal softening, which are frequently observed in high-velocity deformation phenomena, Johnson-Cook model is used as constitutive model. For more accurate and robust contact force computation, the defense node contact algorithm was adopted and implemented. In order to evaluate the performance of the newly developed three-dimensional hydrocode NET3D, numerical simulations of the oblique impact of mild steel plate by mild steel sphere were carried out. Ballistic limit about various oblique angle between 0 degree and 80 degree was estimated through a series of simulations with different initial velocities of sphere. Element eroding by equivalent plastic strain was applied to mild steel spheres and targets. Ballistic limits and fracture characteristics obtained from simulation were compared with experimental results conducted by Finnegan et al. From numerical studies, the following conclusions were reached. (1) Simulations could successfully reproduce the key features observed in experiment such as tensile failure termed "disking"at normal impacts and outwards bending of partially formed plus segments termed "hinge-mode"at oblique impacts. (2) Simulation results fur 60 degrees oblique impact at 0.70 km/s and 0.91 km/s were compared with experimental results and Eulerian hydrocode CTH simulation results. The Lagrangian code NET3D is superior to Eulerian code CTH in the computational accuracy. Agreement with the experimentally obtained final deformed cross-sections of the projectile is excellent. (3) Agreement with the experimental ballistic limit data, particularly at the high-obliquity impacts, is reasonably good. (4) The simulation result is not very sensitive to eroding condition but slightly influenced by friction coefficient.

• 한국추진공학회지
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• 제19권2호
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• pp.17-28
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• 2015

본 논문에서는 ON/OFF 작동과 같이 단순화된 구동 메커니즘을 가지면서도 구동 명령 한계가 있는 시스템의 구동 위치 제어 기법 설계를 수행하였다. 가장 먼저 구동기 시험데이터를 이용하여 고려되는 구동기의 PWM 명령을 입력으로 하는 비선형/선형 구동 동역학 모델링을 수행 하였다. 선형화된 모델을 이용하여 목표로 하는 제어 성능 요구조건을 만족시키기 위한 고전적인 PI 제어기법을 설계하였으며, PWM 제어명령 한계에 따른 제어 성능 감소를 해소하기 위한 제어 알고리즘을 제안하여 유효 제어 범위 내에서 설계된 제어 성능이 구현되도록 하였다. 최종적으로 제어 시뮬레이션을 통해 설계 방법을 검증하고 해당 제어기법 적용에 따른 성능 개선 정도를 평가하였다.

• 한국수산과학회지
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• 제43권4호
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• pp.293-297
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• 2010

To prevent amnesic shellfish poisoning (ASP) resulting from the consumption of shellfish contaminated with domoic acid, the quantitative analysis of domoic acid is very important. We validated a high performance liquid chromatography (HPLC) method for accurate and precise quantification of domoic acid. A clear peak and the isolation of domoic acid resulted on injecting a 50% methanol extract of CRM-ASP-Mus-c mussel reference material using HPLC. The limit of detection of domoic acid under the established HPLC conditions was $0.10\;{\mu}g/g$, and the limit of quantification of the toxin under the same conditions was $0.25\;{\mu}g/g$. The intra-accuracy and precision for domoic acid in CRM-ASP-Mus-c were 90.7-95.7% and 0.28-22.25%, respectively. The inter-accuracy and precision for domoic acid were 89.1-97.1% and 1.7-4.1%, respectively. The mean recovery of domoic acid in methanol extracts from ten species of marine invertebrates was 88.6-1105.1%.