• Title/Summary/Keyword: Obstacle Limit

Search Result 72, Processing Time 0.024 seconds

Vibration Analysis and Experiments of a Chip Mounting Device (칩마운터의 진동 해석 및 실험 분석)

  • 고병식;이승엽
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • 2002.05a
    • /
    • pp.1039-1042
    • /
    • 2002
  • SMD(Surface Mounting Device) which mounts electronic components as IC-Chips on PCB automatically, produces a large dynamic force and vibration. The unwanted vibrations in SMD degrade the performance of the precision device and it is the major obstacle to limit its speed for mounting. This study investigated the vibration analysis of a typical SMD to predict the natural frequencies and mode shapes. To validate the finite element analysis of SMD, the FE result was compared with that of ODS measurements. It was shown that the predicted results were well correlated with the experimental modal parameters.

  • PDF

A Historical Study on the Interaction of the Limit-the Infinite Set and Its Educational Implications (극한과 무한집합의 상호작용과 그 교육적 시사점에 대한 역사적 연구)

  • Park, Sun-Yong
    • Journal for History of Mathematics
    • /
    • v.31 no.2
    • /
    • pp.73-91
    • /
    • 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.

On a Goal-Directed Reactive Navigation Method for a Mobile Robot (이동 로봇의 자율주행을 위한 목표점 지향 반사 주행 방식)

  • 오용환;윤도영;오상록;박귀태
    • The Transactions of the Korean Institute of Electrical Engineers D
    • /
    • v.53 no.4
    • /
    • pp.246-257
    • /
    • 2004
  • This paper proposes two contributions. One is an analysis for the limit of the subject of goal-directed reactive robot navigation, and the other is an effective navigation method employing the scheme of the subject. The analysis for the subject is presented in order to clarify the limit of the method. On the basis of the analysis, a safety-guaranteeing and deadlock-free reactive navigation method is newly proposed. The proposed method has a simple behavior-based frame such that it can make the required navigation tasks such as obstacle avoidance, deadlock resolving, and etc. with a very small set of behaviors in entirely unknown environments such as a living room, an office, and etc. Some results of experiments show these validities.

Development of Auto-Parking Algorithm for Driving in Urban (무인차량의 자동주차 알고리즘 개발)

  • Cho, Kyoung-Hwan;Chung, Jin-Wok
    • Journal of the Korea Academia-Industrial cooperation Society
    • /
    • v.12 no.5
    • /
    • pp.2360-2366
    • /
    • 2011
  • The Unmanned Ground Vehicle is comprised of four systems of obstacle detection: The navigation system, vehicle controlling system, obstacle detecting and an integration system that use the various sensors. The research introduced utilizes 6 lasers to recognize obstacles. The system operates an avoidance system within the unmanned ground vehicle, using six lasers. The Unmanned Ground Vehicle's parallel parking and right angle parking is in development using algorithms. This algorithms' certification is intended to be installed in the encoder, in the GPS. By using the Laser Scannerfor the position's calculation, errors are both reduced and minimized, so the tire's slip minimized to the point where the vehicle had a limit of about 5Km/h.

A Study on Information Networks for Libraries (도서관(圖書館)의 정보(情報) "네트워크"에 관한 연구(硏究))

  • Kwon, Kie-Won
    • Journal of the Korean BIBLIA Society for library and Information Science
    • /
    • v.4 no.1
    • /
    • pp.23-48
    • /
    • 1980
  • Libraries are social apparatuses made by social needs and functions, each class of services and technology in them were changed and developed variously adapting to chronological conditions. There is reaching the interest about development in the information system to deal with it's all materials effectively, but most of libraries are interfacing from the limit of materials and manpower. Some obstacle factors restrained in the attainment of purposes and is made Sufficiently services by librarians through the information networks for libraries, they devise the utilization of materials widely in libraries and information centers. As the pre-condition of library networks, the mathematical model of organization and it's formular, 29 universities and 7 public libraries in seoul are to make the non-directed and the directed networks, and then the former has 5 groups, the latter has 1 group by the switching center. I studied for the switching centers from 6 groups experimentally. Organization, finances, cataloging and Situation that are some obstacle factors of the information networks for libraries were studied the alternatives of them. When we can have supports of the nation actively for the making networks in geographical and various libraries and get grants of it, many agencies and industries, we can achieve the purpose by social apparatuses in the information society.

  • PDF

A Study on Improvement of Aeronautical Study System for Potential Obstacles in the Vicinity of Aerodromes (공항 주변 잠재적 장애물에 대한 항공학적 검토 제도 개선 연구)

  • Lee, Daekyum;Yun, Seokjae;Park, Bomi;Kim, Jechul;Kim, Jun-Hyuk
    • Journal of the Korean Society for Aviation and Aeronautics
    • /
    • v.29 no.4
    • /
    • pp.166-172
    • /
    • 2021
  • Obstacle Limitation Surfaces (OLS) are set to protect a certain amount of airspace to limit objects, such as building, other structures, penetrating OLS for safety and regularity of aircraft operations in the vicinity of aerodromes. However, many civil petitions have been raising for effective utilization of lands and permission of building construction which penetrating OLS. While Republic of Korea are limiting installation of penetrating objects based on the National law of airport facilities, such objects are possibly permitted, only if, the possible risks coming from objects are acceptable or negligible in terms of safety and regularity in aircraft operations through the evaluation process, called as an aeronautical study. However, many countries are currently applying their own criteria, processes resulting in failing secure reliable results in aeronautical study. This research aims to establish the framework on criteria, process, and methodologies how the aeronautical study works including work flows between many stakeholder and responsibilities to be specified in national regulation system.

Analytic Hierarchy Research on Site Selection to Construct Airfield to Contribute to Improve Aviation Safety Focusing on Song-Po Airfield (항공안전 증진을 위한 경비행장 건설에 따른 입지선정 AHP(Analytic Hierarchy Process) 연구 - 송포 비행장을 중심으로 -)

  • Sang Yong Park
    • Journal of the Korean Society for Aviation and Aeronautics
    • /
    • v.31 no.3
    • /
    • pp.71-78
    • /
    • 2023
  • To minimize the occurrence of aviation accidents in the post-COVID, continuous flight training is crucial. However, the current infrastructure of domestic airports and airfields is insufficient to prepare for and respond to accidents, and there is a need for sufficient facility capacity. Therefore, this study examines the construction of a regional airport to minimize aviation accidents and selects factors necessary for determining the site location. Among the 11 selected factors, six were considered the most important site selection factors, including noise issues, weather conditions, obstacle limitations, environmental issues, airspace conditions, and facility usability. Applying these factors, an analysis was conducted on the Songpo area of Sacheon City, Gyeongsangnam-do. Based on a comprehensive review, it can be concluded that the Songpo area is a suitable choice for a regional airport due to its excellent transportation environment, consideration of noise and environmental issues with the residential population, and other factors. Furthermore, the development of the aviation industry is expected to bring about an increase in tourism and economic benefits, and it is anticipated to make a significant contribution to the domestic aviation industry along with the construction of the currently under-construction Ulleung Airport.

A new scheme for finding the biggest rectangle that doesn't have any obstacle (장애물을 제외한 가장 큰 공간을 찾는 기법)

  • Hwang, Jung-Hwan;Jeon, Heung-Seok
    • The KIPS Transactions:PartA
    • /
    • v.18A no.2
    • /
    • pp.75-80
    • /
    • 2011
  • Recently, many cleaning robots have been made with various algorithms for efficient cleaning. One of them is a DmaxCoverage algorithm which efficiently clean for the situation when the robot has a time limit. This algorithm uses Rectangle Tiling method for finding the biggest rectangle that doesn't have any obstacle. When the robot uses grid map, Rectangle Tiling method can find the optimal value. Rectangle Tiling method is to find all of the rectangles in the grid map. But when the grid map is big, it has a problem that spends a lot of times because of the large numbers of rectangles. In this paper, we propose Four Direction Rectangle Scanning(FDRS) method that has similar accuracy but faster than Rectangle Tiling method. FDRS method is not to find all of the rectangle, but to search the obstacle's all directions. We will show the FDRS method's performance by comparing of FDRS and Rectangle Tiling methods.

Numerical Study on Characteristics of Gas Leakage in an Underground Combined Cycle Power Plant (지하 복합발전 플랜트 내부의 가스 누출 특성에 대한 수치해석 연구)

  • Bang, Joo Won;Sung, Kun Hyuk;Ryou, Hong Sun;Lee, Seong Hyuk
    • Journal of the Korea Academia-Industrial cooperation Society
    • /
    • v.17 no.5
    • /
    • pp.594-600
    • /
    • 2016
  • The present study numerically investigated the gas leakage characteristics in a simplified underground combined cycle power plant. The effect of obstacles near a crack location on the gas concentration in the confined space was analyzed by using the lower flammable limit (LFL) of methane gas. When the jet flow was close to the vertical walls, the longitudinal leakage distance increased by about 60% (when an obstacles was present) compared to the case without any obstacle, because these obstacles prevented transverse flows. In addition, when an air filter was installed near to the trajectory of the gas flow, the longitudinal leakage distance was similar to the distance between the crack and obstacle, whereas the transverse leakage distance increased up to 8 times compared to the case without any obstacle. As the jet flow impacts on the obstacle and changes its direction, the gas flows recirculate. Therefore, it is necessary to consider the effect of the structure and facility locations on the trajectory of the jet flow to propose an accident prevention system in confined spaces.

A Study on the Infrared Local Heat Treatment of Curved Line for Aluminum Alloy Sheet (알루미늄 판재의 성형성 향상을 위한 적외선 국부 열처리법의 곡선형태 적용에 관한 연구)

  • Lee, E.H.;Yang, D.Y.
    • Transactions of Materials Processing
    • /
    • v.27 no.2
    • /
    • pp.87-92
    • /
    • 2018
  • Auto industries have tried to employ lightweight alloys to improve the fuel efficiency of manufactured vehicles, as the environmental concern becomes an important issue. Even though the aluminum alloy is one of the most appropriate lightweight alloys for auto parts, the low formability of an aluminum alloy has been an obstacle to its application. In order to resolve the low formability problem, a recent study (Lee et al., 2017 [1]) showed that the infrared (IR) local heat treatment can improve the formability with a reduction of heating energy. However, the aforementioned study was limited to only a linear line heating. Since many of the available auto parts as applicable to vehicle manufacturing have a curved line shape, the heating experiments for a curved line should be studied. The possibility of building IR lamps having complex shapes is an advantage of the IR lamp, since it can control the heating shape. This work conducted the IR local heat treatment for the curved line. The experimental results show that the IR local heat treatment can improve the formability of the aluminum alloy for curved line. Additionally, it is shown that the IR local heat treatment also reduces the heating energy when it is compared with the furnace heating which heats a blank as a whole. A numerical simulation with a stress-based forming limit diagram also supports the experimental results.