• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2015년도 제46회 하계학술대회
• /
• pp.280-281
• /
• 2015

DC 그리드가 실현되기 위해서는 이를 둘러싸고 있는 AC 시스템 간의 상호작용에 대한 이해가 필요하며, 차단기의 용량을 결정하거나 차단기를 동작시키기 위한 보호 계전기의 정정 등에 고장 전류값이 사용되기 때문에 사고 발생시 고장 전류에 대한 검토가 필요하다. 따라서, 본 논문에서는 DC 그리드의 내에서의 고장 전류 특성을 파악하기 위해 PSCAD/EMTDC를 이용하여 Point-to-Point VSC HVDC 그리드를 구성하여 Pole 상태 및 고장 종류에 따른 DC 그리드의 고장특성에 대한 연구를 수행하였다.

• 대한수학회보
• /
• 제45권3호
• /
• pp.573-585
• /
• 2008

A few sufficient conditions for the existence and uniqueness of fixed point and common fixed point for certain contractive type mappings in complete metric spaces are provided. Several existence and uniqueness results of solution and common solution for some functional equations and system of functional equations in dynamic programming are discussed by using the fixed point and common fixed point theorems presented in this paper.

• 한국환경과학회지
• /
• 제26권4호
• /
• pp.467-481
• /
• 2017

This study sought to determine the changes in weather conditions in urban streets, along with conditions of traffic and roads in urban areas. The variations in weather conditions depending on traffic differed according to distance. First, the temperature difference measured by traffic results is as follows: T1 point $1.03^{\circ}C$, T2 point $1.04^{\circ}C$, T3 point $0.9^{\circ}C$, T4 point $1.01^{\circ}C$, and T5 point $0.31^{\circ}C$. The average difference between the measured temperatures by the point of measurement was $0.86^{\circ}C$. The changes in wind velocity according to traffic volume results of the measurements is T1 point 1.32 m/s, T2 point 0.80 m/s, T3 point 0.29 m/s, T4 point 0.04 m/s, and T5 point 0.09 m/s. The difference between the average wind speeds was 0.51 m/s and traffic jams caused substantial differences in distance. The relative humidity tended to be inversely proportional to temperature. The measurements results ares T1 point 2.29%, T2 point 2.67%, T3 point 2.47%, T4 point 2.16%, and T5 point 0.91% The difference between the average relative humidity was 7.3%. In case of independent sampling T test according to traffic volume, changes in wind velocity and temperature were directly proportional to the level of statistical significance(p<0.01). On the other hand, relative humidity tended to be inversely proportional; however, there was no statistical significance.

• 대한수학회보
• /
• 제27권2호
• /
• pp.127-131
• /
• 1990

Let f:R.rarw.R be a continuous function on the real line R, and denote the n-th iterate of f by f$^{n}$ :f$^{1}$=f and f$^{n}$ =f.f$^{n-1}$ for n>1. A point x.mem.R is a periodic point of f of period k>0 if f$^{k}$ (x)=x but f$^{i}$ (x).neq.x for all 01, then it must also have a fixed point, by the intermediate Theorem. Also the question has an intriguing answer which was found by ths Russian mathematician Sharkovky [6] in 1964.

• 대한전자공학회논문지TC
• /
• 제43권11호
• /
• pp.95-117
• /
• 2006

본 논문에서는 IEEE 802.16e OFDMA/TDD 이동국 모뎀의 링크 성능과 복잡도 최적화를 위한 부동 및 고정 소수점 설계에 대하여 논한다. 부동 소수점 설계에서는 이동국 모뎀에서 하향링크 트래픽 채널의 채널 추정 방법을 제안하고, 모의실험을 통하여 최적의 알고리즘을 선정한다. 그리고 시간 및 주파수 동기화, Digital Front End와 CINR 추정 기법에 관하여 성능 향상과 시스템을 최적화하기 위한 알고리즘을 제안하고, 상향링크의 트래픽 채널과 제어 채널의 부동 소수점 설계 방법을 논한다. 제안된 알고리즘은 IEEE 802.16e OFDMA/TDD 시스템에 적용하여, 모의실험을 통한 성능을 Detection Probability, Mean Acqusition Time, PER 성능 그래프 등으로 그 우수성을 검증한다. 고정 소수점 설계에서는 부동 소수점 설계로부터 최적의 고정 소수점 설계를 위한 효율적인 방법론을 제시한다. 그리고 하향링크와 상향링크의 트래픽 채널, 시간 및 주파수 동기, DFE 블록을 고정 소수점 설계하고, 모의실험을 통하여 성능과 복잡도 간의 tradeoff 관계를 최적화한다.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2005년도 ICCAS
• /
• pp.2325-2330
• /
• 2005

A potential field method for solving the problem of path planning based on global and local information for a mobile robot moving among a set of stationary obstacles is described. The concept of various method used path planning is used design a planning strategy. A real human living area is constructed by many moving and imminence obstacles. Home service mobile robot must avoid many obstacles instantly. A path that safe and attraction towards the goal is chosen. The potential function depends on distance from the goal and heuristic function relies on surrounding environments. Three additional combined methods are proposed to apply to human living area, calibration robots position by measured surrounding environment and adapted home service robots. In this work, we proposed the application of various path planning theory to real area, human living. First, we consider potential field method. Potential field method is attractive method, but that method has great problem called local minimum. So we proposed intermediate point in real area. Intermediate point was set in doorframe and between walls there is connect other room or other area. Intermediate point is very efficiency in computing path. That point is able to smaller area, area divided by intermediate point line. The important idea is intermediate point is permanent point until destruction house or apartment house. Second step is move robot with sensing on front of mobile robot. With sensing, mobile robot recognize obstacle and judge moving obstacle. If mobile robot is reach the intermediate point, robot sensing the surround of point. Mobile robot has data about intermediate point, so mobile robot is able to calibration robots position and direction. Third, we gave uncertainty to robot and obstacles. Because, mobile robot was motion and sensing ability is not enough to control. Robot and obstacle have uncertainty. So, mobile robot planed safe path planning to collision free. Finally, escape local minimum, that has possibility occur robot do not work. Local minimum problem solved by virtual obstacle method. Next is some supposition in real living area.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
• /
• 제3권1호
• /
• pp.75-80
• /
• 1999

An investigation of noise and vibration caused by the reclamation of the foreshore around J village resulted in noise measurements of 56-84 dB at the first point, 62-81 dB at the second point, and 68-78 dB at the third point. These measurements were higher than the standard level of environmental noise that is 55 dB at noon and 45 dB at night. The vibration measurements were 61-83 dB at the first point, 63-88 dB at the second point, and 58-77 dB at the third point. These measurements were also higher than the standard level of environmental vibration that is 60 dB at noon and 54 dB at night. The measurements of scattering dust were 80 $\mu\textrm{g}$/$\textrm{m}^3$ at the first point, 120 $\mu\textrm{g}$/$\textrm{m}^3$ at the second point, and 169 $\mu\textrm{g}$/$\textrm{m}^3$ at the third point. These measurements were lower than the standard level of environmental dust that is 300 $\mu\textrm{g}$/$\textrm{m}^3$/day. Although the maximum vibration level was higher than the standard level of environmental vibration, it had no influence on the construction.

• Journal of applied mathematics & informatics
• /
• 제25권1_2호
• /
• pp.425-434
• /
• 2007

We iteratively generate a sequence of measurable mappings and study necessary conditions for its convergence to a random fixed point of random nonexpansive operator. A random fixed point theorem for random nonexpansive operator, relaxing the convexity condition on the underlying space, is also proved. As an application, we obtained random fixed point theorems for Caristi type random operators.

• 한국수학교육학회지시리즈B:순수및응용수학
• /
• 제10권4호
• /
• pp.245-254
• /
• 2003

In this paper we prove common fixed point theorems for four mappings, under the condition of weakly compatible mappings in Menger spaces, without taking any function continuous. We improve results of [A common fixed point theorem for three mappings on Menger spaces. Math. Japan. 34 (1989), no. 6, 919-923], [On common fixed point theorems of compatible mappings in Menger spaces. Demonstratio Math. 31 (1998), no. 3, 537-546].

• Korean Journal of Mathematics
• /
• 제20권3호
• /
• pp.353-360
• /
• 2012

In this paper we introduce the property (C), which is a cone metric extension of the usual metric property (E,A) and consider fixed point theorems for generalized contractive mappings under suitable conditions in cone metric spaces without normal cones.