• 산업기술연구
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• 제16권
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• pp.247-256
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• 1996

The multilevel grid file(MLGF) is a dynamic multidimensional file organization supporting multi-attribute accesses efficiently. The paper proposes new method for batch-constructing MLGFs. Our method consists of two phases. The first phase begins by relocating all the objects in order that logically adjacent objects in multidimensional domain space are clustered in one dimensional physical space. For this, our method employs the Z-ordering scheme, which effectively maps multidimensional space into one dimensional space preserving proximity. The second phase paginates the relocated objects and creates leaf level directory entries, each of which corresponds to a object page. Simultaneously, it performs same actions on the directory entries recursively in a bottom-up fashion until the root directory fits in a page. For performance evaluation, we analyze our method in terms of the number of page accesses. The result shows the optimality of our method.

• 한국지능시스템학회논문지
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• 제21권6호
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• pp.686-691
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• 2011

This study is concerned with the identification of fuzzy models. To address the optimization of fuzzy model, we proposed an improved space search evolutionary algorithm (ISSA) which is realized with the combination of space search algorithm and Gaussian mutation. The proposed ISSA is exploited here as the optimization vehicle for the design of fuzzy models. Considering the design of fuzzy models, we developed a hybrid identification method using information granulation and the ISSA. Information granules are treated as collections of objects (e.g. data) brought together by the criteria of proximity, similarity, or functionality. The overall hybrid identification comes in the form of two optimization mechanisms: structure identification and parameter identification. The structure identification is supported by the ISSA and C-Means while the parameter estimation is realized via the ISSA and weighted least square error method. A suite of comparative studies show that the proposed model leads to better performance in comparison with some existing models.

• Journal of Astronomy and Space Sciences
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• 제41권1호
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• pp.35-42
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• 2024

Sungrazing comets, known for their proximity to the Sun, are traditionally classified into broad groups like Kreutz, Marsden, Kracht, Meyer, and non-group comets. While existing methods successfully categorize these groups, finer distinctions within the Kreutz subgroup remain a challenge. In this study, we introduce an automated classification technique using the densitybased spatial clustering of applications with noise (DBSCAN) algorithm to categorize sungrazing comets. Our method extends traditional classifications by finely categorizing the Kreutz subgroup into four distinct subgroups based on a comprehensive range of orbital parameters, providing critical insights into the origins and dynamics of these comets. Corroborative analyses validate the accuracy and effectiveness of our method, offering a more efficient framework for understanding the categorization of sungrazing comets.

• 우주기술과 응용
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• 제2권1호
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• pp.30-40
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• 2022

본 논문에서는 초소형 위성을 활용한 랑데부/도킹 기술검증 시 초기 발사 이후 표류(drift) 거리 회복(recovery)과 근접 운용을 위한 시나리오 설계에 대해 기술하였다. 랑데부/도킹은 궤도상서비싱(on-orbit servicing, OOS) 기술의 기반이 되는 기술로서 목표 물체에 접근하는 데 반드시 필요한 선제적인 과정이다. 특히 우주상에서 검증이 어려운 기술로서 개발 단계의 위험성 및 비용 등을 줄이기 위하여 최근에는 초소형 위성이 활용되고 있다. 따라서 본 논문에서는 랑데부/도킹 기술 검증을 위한 초소형 위성의 추력기 구성과 제원을 소개하며, 초소형 위성의 작은 크기 및 낮은 전력에서 오는 추력 한계를 고려할 수 있는 상대 궤적을 설계하고자 한다. 또한 추력 한계를 고려하지 않은 경우와의 궤적 및 추력 사용량 등의 비교를 통해 추후 사용 가능한 추력기의 성능 향상에 따른 시나리오 설계에도 도움이 되고자 한다.

• 한국주거학회논문집
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• 제16권2호
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• pp.11-17
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• 2005

The purpose of this study is to find the characteristics of planning factors to the outdoor space of the olympic village munchen. The result of the research are follows; 1) The horizontal gardens of the low buildings and hanging gardens on the terraces of the high-rise buildings are intended as a continuation of the concept of the modelled landscape. 2) By virtue of the choice of the type of building and the way in which the buildings are staggered, the residents have an unimpaired view of the green spaces and recreation areas. 3) Leisure value is further enhanced by the proximity of the residential arms to the footpath running north to south. 4) The terraces allow the residents to enjoy more sun and sky, so that the view into the distance is the rule. 5) To improve orientation, the pedestrian paths to the residential wings are also situated directly over the underground vehicle-access roads.

• 대한건축학회논문집:계획계
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• 제35권10호
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• pp.19-30
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• 2019

The purpose of this study is to explore ways to efficiently capture the opinions of students who are main users in the planning, planning and design of school facilities. There are many criteria for determining good schools, but in this study, the main purpose of this study was to set up the main users as students, and to analyze the differences between the network and the actual spatial structure (network) created by the hope of students' use of school space, and the direction to overcome the differences. After surveying students' opinions about their satisfaction with school space and their desire to use school space by limiting the survey target to middle and high schools in Seoul, the 'social-space network analysis' was recently established in the social science field. As a result, it was found that the proximity of space and space desired by students in the school varied greatly depending on the geographical conditions, school districts, and the status of the current facilities, and the direction of improvement specialized for each school was found.

• 터널과지하공간
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• 제27권5호
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• pp.282-294
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• 2017

본 연구에서는 광산안전관리를 위한 충돌방지시스템의 개발 현황과 적용사례를 분석하였다. 광업 선진국인 미국과 호주에서 사용하는 충돌방지시스템의 용어를 정의하고 이용되는 센서 기술들을 비교하였다. 또한 해외의 광산 회사들이 개발한 충돌방지시스템인 $MineAlert^{TM}$ Collision Awareness System, Cat $MineStar^{TM}$, Intelligent Proximity Detection 기술 등에 대해 소개하였다. 국내 광업 분야에서는 충돌방지시스템을 개발한 사례가 없었으며 건설과 철도 분야에서 이와 유사한 개념의 시스템을 확인할 수 있었다. 충돌방지시스템을 도입하면 광산에서 발생할 수 있는 충돌사고를 방지하여 작업자의 안전을 개선시킬 수 있을 것이며, 해외의 개발 사례를 통해 국내 광산 환경에 적합한 센서 기술을 개발하고 적용하는 연구가 필요할 것으로 판단된다.

• 한국컴퓨터정보학회논문지
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• 제29권3호
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• pp.83-90
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• 2024

본 연구에서는 멀티미디어 환경에서 상호작용 시스템 중 하나인, 음성 대화 기술에 대하여 근접 음성 대화 시스템을 적용하는 솔루션을 제안한다. 사용자 아바타들 간 거리에 따라 음성의 볼륨을 조절하고, 가청 거리를 벗어난 사용자에게는 음소거를 적용하는 방식으로 멀티미디어 공간에서 여러 사용자 간의 음성 대화 방식을 설계하였다. 본 연구의 가장 큰 특징은 경제적인 개발을 위해, 거리를 기반으로 먼 거리에 있는 사용자에게는 저음질의 음성을 전달하고, 비 가청 지역에 들어선 사용자에게는 음성 데이터를 전송하지 않게 하는, reliable UDP 기반 능동적 서버 시스템에 있다. 제안 시스템은 사전에 완성하였던 유니티 게임 엔진 기반 프로젝트에서 성능을 측정하였으며, 본 연구에서 제안한 시스템을 메타버스 콘텐츠, 실시간 대전 액션 게임과 같이 여러 사용자 간 상호작용을 제공하는 환경에서 적극적으로 이용되는 것을 기대할 수 있다.

• 천문학회보
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• 제44권1호
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• pp.66.4-66.4
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• 2019

NGC 6822 is a dwarf irregular galaxy whose metal abundance is lower than of the Large Magellanic Cloud. Hubble V is the brightest HII complex where molecular clouds surround the core cluster of OB stars. Because of its proximity (d = 500 kpc), we can resolve the star-forming regions on parsec scales (1 arcsec = 2.4 pc). Using the high-resolution (R = 45,000) near-infrared spectrograph, IGRINS, we observed molecular hydrogen emission lines from photo-dissociation regions (PDRs) and $Br{\gamma}$ emission line from ionized regions. In this presentation, we compare our data PDR models in order to derive the density distribution of the molecular clouds on parsec scales and to estimate the total mass of the clouds.

• Journal of Biosystems Engineering
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• 제25권5호
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• pp.351-358
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• 2000

This study was conducted to develop a speed control system of a DC motor which drove a barley seeder mounted on a combine harvester. Barley seeder mounted on a combine has been known to reduce labor and cost of barley cultivation. However, development of the seeder has been unsuccessful because the combine, a dedicated rice and barley harvester has not enough space and proper power take-off for barley seeder. To develop a barley seeder, small powered motor speed controller was required. A proximity sensor for detecting working speed of the combine and a programmable one board microprocessor was used to develope a control system. Motor parameters and motor constant, relationship between seeding rate, motor speed, groove volumes of a tested roller, torque were measured. The proximity sensor sent a frequency signal to the microprocessor. In laboratory experiments, the excitation voltage of the motor was shown not to be proportional to the size of pulse width (duty ratio). A table transforming frequency signal, that represented for working speed to proper pulse width was developed from seeding rate experiments. However, seeding rate at low frequency signal was not proportional to the working speed. Seeding rate control proportional to the frequency signal was achieved by shifting of the frequency signal.