• Title/Summary/Keyword: proximity space

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The Study on the Fragment Ejection Velocity and Spray Angle from a High Explosive Cylindrical Warhead (실린더형 HE 탄두 폭발 시 파편의 속도 및 발사각 추정방법 연구)

  • Hwang, Changsu;Park, Younghyun;Park, Seikwon;Jung, Daehan;Lee, Moonsik;Kang, Sunbu;Kim, Deuksu
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.47 no.12
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    • pp.904-912
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    • 2019
  • We have studied the numerical analysis about the fragment ejection velocity and spray angle when the High Explosive warhead detonated at proximity distance at an aircraft. To study the physical quantities about the warhead components is very important to assessment the vulnerability of aircraft. Generally, the physical quantities about the components of a warhead such as the mass, length, diameter and charge to mass ratio are unknown. Therefore, it is required to estimate the physical quantities by using physical continuities of similar threats. The empirical formulas to understand the dependence among charge to mass ratio, length and diameter ratio were driven by using the physical parameters of similar threatening such as terrier, sparrow. As a result, we confirmed that the dead mass ratio was closed to 20% of warhead mass since the metal case of the proximity threat acts as a simple carrier. This implies that the effective length and diameter of High Explosive Compound is smaller than the length and diameter of warhead, and become a key to understand the large ejection gradient velocity and small spray angle of fragments within 6 degree.

Reordering Scheme of Location Identifiers for Indexing RFID Tags (RFID 태그의 색인을 위한 위치 식별자 재순서 기법)

  • Ahn, Sung-Woo;Hong, Bong-Hee
    • Journal of KIISE:Databases
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    • v.36 no.3
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    • pp.198-214
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    • 2009
  • Trajectories of RFID tags can be modeled as a line, denoted by tag interval, captured by an RFID reader and indexed in a three-dimensional domain, with the axes being the tag identifier (TID), the location identifier (LID), and the time (TIME). Distribution of tag intervals in the domain space is an important factor for efficient processing of a query for tracing tags and is changed according to arranging coordinates of each domain. Particularly, the arrangement of LIDs in the domain has an effect on the performance of queries retrieving the traces of tags as times goes by because it provides the location information of tags. Therefore, it is necessary to determine the optimal ordering of LIDs in order to perform queries efficiently for retrieving tag intervals from the index. To do this, we propose LID proximity for reordering previously assigned LIDs to new LIDs and define the LID proximity function for storing tag intervals accessed together closely in index nodes when a query is processed. To determine the sequence of LIDs in the domain, we also propose a reordering scheme of LIDs based on LID proximity. Our experiments show that the proposed reordering scheme considerably improves the performance of Queries for tracing tag locations comparing with the previous method of assigning LIDs.

SPGS: Smart Parking Space Guidance System based on User Preferences in a Parking Lot (사용자 선호도 기반의 스마트 주차 공간 안내 시스템)

  • Yoo, Seong-eun
    • Journal of Korea Society of Industrial Information Systems
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    • v.24 no.4
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    • pp.29-36
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    • 2019
  • We propose a smart parking space guiding system based on user preferences in a parking lot. This system guides each vehicle to the most suitable parking space in a parking lot to meet the user preferences such as the available parking spaces in the parking zones and the proximity to the destination by exploiting the traffic to each parking zone gathered at the sensors near each guiding display. For this purpose, this paper proposes the cost function for the optimal route guide based on the various user preferences. In addition, the paper reports the design and implementation results of an event based simulator to show the feasibility of the smart parking guidance system.

A Study on the Layout Patterns of Public Schools in Manhattan - Focused on Relationship between Manhattan Grid Plan and Open Space - (뉴욕시 공립학교에 나타난 배치 특성에 관한 연구 - 맨하튼 가로체계와 외부공간의 관계를 중심으로 -)

  • Kim, Pil-Soo;Jeon, You-Chang
    • Journal of the Korean Institute of Educational Facilities
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    • v.20 no.2
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    • pp.3-14
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    • 2013
  • The purpose of this study is to analyze patterns of public school building layout types, open space and relationship with communities in the Manhattan grid plan. The study illustrates how building layout patterns of school facilities are influenced by societal demands in the urban grid environment. During the nineteenth century, the Island of Manhattan was transformed into a physical representation of the Cartesian coordinate system via the development of the grid street plan. In order to take advantage of streets as urban space, it is quite important to understand characteristics of communities and open space relationships between buildings and streets. Moreover, the strategic planning of schools' outdoor space vitalizes public streets as a critical community anchor. This research reviews 118 Manhattan public schools and categorizes them by (1) building layout type, (2) site type, (3) circulation and public open space, which are the biggest factors that determine the layout patterns of the public schools in Manhattan. As a result of analysis, the layout patterns are classified into seven types : "ㅡ", "L", "ㄷ", "ㅁ", "H", "T" and "other" type. Of these, "ㅡ" type and "L" type occur most frequently, because these configurations most flexibly fit into the limited grid-locked blocks, the various types of site & topography, and adapt most dynamically to the open spaces created by using avenues and streets. The ultimate objective of this study is to provide a case study for future efforts to plan open spaces for campuses that effectively utilize the streets in proximity.

DEEP-South: Preliminary Lightcurve Analysis of Potentially Hazardous Asteroids (PHAs)

  • Kim, Myung-Jin;Moon, Hong-Kyu;Choi, Young-Jun;Yim, Hong-Suh;Park, Jintae;Roh, Dong-Goo;Lee, Hee-Jae;Oh, Young-Seok
    • The Bulletin of The Korean Astronomical Society
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    • v.41 no.1
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    • pp.55.1-55.1
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    • 2016
  • Near Earth Asteroid (NEA) population has attracted keen attention not only from the scientific community but from the general public ever since their terrestrial impact risk achieved wide recognition. Potentially Hazardous Asteroids (PHAs), the subset of NEAs, recently became the center of interest of planetary defense folks and mining industry due to their proximity to, and the potential effects on planet Earth. However, we have long been ignorant about either the physical properties or dynamical source regions of individual objects. For instance, their rotational periods are only known for five percent of the total population (The NEA Database of DLR, updated on Feb 2016). The primary scientific objective of DEEP-South (DEep Ecliptic Patrol of the Southern sky) is to physically characterize 70 percent of km-class PHAs until 2019. In order to achieve this goal, we implemented an observation mode so-called "OC (Opposition Census)" targeting objects around opposition. OC observations were conducted during the period between Feb 2015 and Mar 2016, at CTIO in early periods, and at three KMTNet stations (CTIO, SSO and SAAO) since late July 2015, excluding the "bulge season" when the telescope time is exclusively used for exoplanet search. We present the preliminary lightcurves of 66 PHAs and 59 NEAs that we obtained during the OC runs.

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Smart space framework providing dynamic embedded intelligent information (사용자 맞춤 동적 지능형 환경을 제공하는 스마트 공간 프레임워크)

  • Jang, SeoYoon;Kang, JiHoon
    • Smart Media Journal
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    • v.10 no.2
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    • pp.92-99
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    • 2021
  • Smart space is a technology that supports humans by interacting with the surrounding environment. Smart space has a built-in dynamic intelligent environment. This paper proposes a framework that provides user-customized dynamic intelligent environments in smart spaces. In the existing research that provides user-customized intelligent services, users' interests are only explicitly analyzed, and smart spaces are not considered. Implicit interest analysis can suggest a service that may be of interest to users rather than explicit interest analysis, but it requires higher performance than explicit interest analysis. Smart spaces can obtain useful information by interacting with information in the space. The framework proposed in the study uses a proximity-based social network of things to fit into a smart space. In addition, the implicit interest analysis provides intelligent information for smart spaces using the social media information and spatial information objects. In addition, we propose a method to prevent performance degradation while maintaining accuracy in consideration of the characteristics of the smart space.

On Motion Planning for Human-Following of Mobile Robot in a Predictable Intelligent Space

  • Jin, Tae-Seok;Hashimoto, Hideki
    • International Journal of Fuzzy Logic and Intelligent Systems
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    • v.4 no.1
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    • pp.101-110
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    • 2004
  • The robots that will be needed in the near future are human-friendly robots that are able to coexist with humans and support humans effectively. To realize this, humans and robots need to be in close proximity to each other as much as possible. Moreover, it is necessary for their interactions to occur naturally. It is desirable for a robot to carry out human following, as one of the human-affinitive movements. The human-following robot requires several techniques: the recognition of the moving objects, the feature extraction and visual tracking, and the trajectory generation for following a human stably. In this research, a predictable intelligent space is used in order to achieve these goals. An intelligent space is a 3-D environment in which many sensors and intelligent devices are distributed. Mobile robots exist in this space as physical agents providing humans with services. A mobile robot is controlled to follow a walking human using distributed intelligent sensors as stably and precisely as possible. The moving objects is assumed to be a point-object and projected onto an image plane to form a geometrical constraint equation that provides position data of the object based on the kinematics of the intelligent space. Uncertainties in the position estimation caused by the point-object assumption are compensated using the Kalman filter. To generate the shortest time trajectory to follow the walking human, the linear and angular velocities are estimated and utilized. The computer simulation and experimental results of estimating and following of the walking human with the mobile robot are presented.

Ground Test of Docking Phase for Nanosatellite (초소형위성 지상 환경 도킹 시험)

  • Kim, Hae-Dong;Choi, Won-Sub;Kim, Min-Ki;Kim, Jin-Hyung;Kim, KiDuck;Kim, Ji-Seok;Cho, Dong-Hyun
    • Journal of Space Technology and Applications
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    • v.1 no.1
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    • pp.7-22
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    • 2021
  • In this paper, we describe the results of the docking phase test in the ground environment of the rendezvous/docking technology verification satellite under development for the first time in Korea. rendezvous/docking technology is a high-level technology in space technology, which is also very important for accessing and performing tasks on relative objects in space orbit. In this paper, we describe the ground test results that the chaser finally docks the fixed target using an air bearing device. Based on the thrust control algorithm in the docking phase and the relative object recognition and relative distance estimation algorithm using visual-based sensors validated in this paper, we intend to use them for later expansion to rendezvous/docking algorithms in three-dimensional space for testing in space.

Study on the Feasibility of Space Weapon Development Utilizing Active Debris Removal Techniques and Understanding of Space Maneuver Warfare (우주 쓰레기 제거기술을 활용한 우주무기 개발 개연성 고찰 및 우주기동전(Space Maneuver Warfare)의 이해)

  • Seonghwan Choi
    • Journal of Space Technology and Applications
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    • v.3 no.2
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    • pp.165-198
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    • 2023
  • According to the studies recently published through advanced maui optical and space surveillance technologies (AMOS) Conference 2021, LEO conjunction assessment revolves around not on operating satellites but space debris such as rocket bodies and non-operational satellites, hence suggesting a solution through space traffic management. Against this backdrop, the issue of active debris removal (ADR) has emerged to the surface as an international challenge throughout the globe. In step with this, the United Nations General Assembly approved a resolution calling on nations to halt tests of direct-ascent anti-satellites, to which U.S. and twelve other nations included Republic of Korea were original signatories. ADR techniques are also actively being researched in the civil sector, and these commercial services, if successfully developed, could possibly be utilized for military use as well. As such, this paper will help readers' understanding for the current status of ADR techniques, space threat assessments, on-orbit rendezvous and proximity operations by looking at previous cases, reflecting on space-faring nations' ADR techniques and its development probability in relation to space weapons. As a conclusion, this study will propose the needs of developing space propulsion system by understanding Space Maneuver Warfare in preparation for the future space battlefield.

Mono-Vision Based Satellite Relative Navigation Using Active Contour Method (능동 윤곽 기법을 적용한 단일 영상 기반 인공위성 상대항법)

  • Kim, Sang-Hyeon;Choi, Han-Lim;Shim, Hyunchul
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.43 no.10
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    • pp.902-909
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    • 2015
  • In this paper, monovision based relative navigation for a satellite proximity operation is studied. The chaser satellite only uses one camera sensor to observe the target satellite and conducts image tracking to obtain the target pose information. However, by using only mono-vision, it is hard to get the depth information which is related to the relative distance to the target. In order to resolve the well-known difficulty in computing the depth information with the use of a single camera, the active contour method is adopted for the image tracking process. The active contour method provides the size of target image, which can be utilized to indirectly calculate the relative distance between the chaser and the target. 3D virtual reality is used in order to model the space environment where two satellites make relative motion and produce the virtual camera images. The unscented Kalman filter is used for the chaser satellite to estimate the relative position of the target in the process of glideslope approaching. Closed-loop simulations are conducted to analyze the performance of the relative navigation with the active contour method.