• Transactions on Electrical and Electronic Materials
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• 제15권3호
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• pp.125-129
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• 2014

A dataset can be clustered by merging the bucket indices that come from the random projection of locality sensitive hashing functions. It should be noted that for this to work the merging interval must be calculated first. To improve the feasibility of large scale data clustering in high dimensional space we propose an enhanced Locality Sensitive Hashing Clustering Method. Firstly, multiple hashing functions are generated. Secondly, data points are projected to bucket indices. Thirdly, bucket indices are clustered to get class labels. Experimental results showed that on synthetic datasets this method achieves high accuracy at much improved cluster speeds. These attributes make it well suited to clustering data in high dimensional space.

• Architectural research
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• 제17권2호
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• pp.57-64
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• 2015

In architectural planning, previous cases of similar spatial program provide important data for architectural design. Case-based reasoning (CBR) paradigm in the field of architectural design is closely related to the designing behavior of a planner who makes use of similar architectural designs and spatial programs in the past. In CBR, spatial graph can be constituted with most fundamental data, which can provide a method of searching spatial program by using visual graphs. This study developed a system for CBR that can analyze the similarity through graph comparison and search for buildings. This is an integrated system that is able to compare space similarity of different buildings and analyze their types, in addition to the analysis on a space within a single structure.

• 한국생산제조학회지
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• 제24권1호
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• pp.87-93
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• 2015

The dynamic responses of a telescope loaded on an STSAT-3 satellite were analyzed, and environmental tests were conducted to verify the reliability of the design. The space use telescope COMIS (compact imaging spectrometer) is a major payload of the STSAT-3 launched on November 21, 2013. Vibration responses such as the acceleration, displacement, and velocity with respect to random vibration and shock impulse inputs were obtained based on theoretical fundamentals in conjunction with finite element analysis. The main focus of this study was on developing technology for accurate and/or favorable modeling and analysis of the structure and fitting the results to that of experiments. Cutting-edge technology for manipulating the vibrations of a space use telescope is suggested.

• Journal of Power Electronics
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• 제11권1호
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• pp.28-36
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• 2011

In this paper, a three phase cycloconverter type high frequency AC link inverter is discussed. The configuration consists of a high frequency full-bridge inverter and a high frequency transformer followed by a three phase cycloconverter whose switch is composed of anti-series connected MOSFETs with a common source. A simple digital control strategy based on space vector modulation (SVM) and repetitive control for the cycloconverter is proposed although its input voltage is a high frequency AC pulse. The operation principle of the proposed control strategy is analyzed and the equivalent working modes during one interval are also presented. The effectiveness of the proposed control strategy is verified through Matlab/Simulink simulations and experiments on a 1.45kW prototype.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제6권9호
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• pp.2341-2350
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• 2012

Face detection is the first step of vision-based driver fatigue detection method. Traditional face detection methods have problems of high false-detection rates and long detection times. A space-time restrained Adaboost method is presented in this paper that resolves these problems. Firstly, the possible position of a driver's face in a video frame is measured relative to the previous frame. Secondly, a space-time restriction strategy is designed to restrain the detection window and scale of the Adaboost method to reduce time consumption and false-detection of face detection. Finally, a face knowledge restriction strategy is designed to confirm that the faces detected by this Adaboost method. Experiments compare the methods and confirm that a driver's face can be detected rapidly and precisely.

• International Journal of Aeronautical and Space Sciences
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• 제14권3호
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• pp.215-221
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• 2013

The basic quantitative tool for the study of hypersonic rarefied flows is the direct simulation Monte Carlo method (DSMC). The DSMC method requires a large amount of computer memory and performance and is unreasonably expensive at the first stage of spacecraft design and trajectory analysis. A possible solution to this problem is approximate engineering methods. However, the Monte Carlo method remains the most reliable approach to compare to the engineering methods that provide good results for the global aerodynamic coefficients of various geometry designs. This paper presents the calculation results of aerodynamic characteristics for spacecraft vehicles in the free molecular, the transitional and the continuum regimes using the local engineering method. Results and methods would be useful to calculate aerodynamics for new-generation hypersonic vehicle designs.

• 한국태양에너지학회 논문집
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• 제27권4호
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• pp.147-155
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• 2007

It is essential to investigate the structure and the main characteristic of Home USN (Ubiquitous Sensor Network) technologies in built ubiquitous environment while designing future residential space. For this study, three different housing types have been selected to implement ubiquitous technologies for residential space; those are regular, elderly, and single residence units. It is certain that efficiency of ubiquitous home design is improved if main components of each specific housing type are analyzed precisely in digital way and design models are prepared accordingly. Ubiquitous technology, in conclusion, has to be applied not on)r with systematical mechanism or electronic setting but in human-centered atmosphere as well, keeping with deep consideration for bio-housing service factors in eco-friendly surrounding; we call this Ubiquitous Humanism.

• 마이크로전자및패키징학회지
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• 제19권1호
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• pp.25-32
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• 2012

Package for artificial satellite is to produce mass production for high package with reliability certification as well as develop SDRAM (synchronous dynamic RAM) module which has such as miniaturization, mass storage, and high reliability in space environment. It requires sophisticated technology with chip stacking or package stacking in order to increase up to 4Gbits or more for mass storage with space technology. To make it better, we should secure suitable processes by doing design, manufacture, and debugging. Pin type PCB substrate was then applied to QFP-Pin type 3D memory package fabrication. These results show that the 3D memory package for artificial satellite scheme is a promising candidate for the realization of our own domestic technologies.

• 한국군사과학기술학회지
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• 제27권3호
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• pp.329-337
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• 2024

Free-space optical communication technology enables the high-speed data transmission and excellent anti-jamming security. We conduct research on satellite-to-ground free-space optical communication links for high-speed transmission of large-capacity surveillance and reconnaissance data. Since the satellite continues to move along its orbit while the optical signal is transmitted between the satellite and the ground, the pointing angle of the beam from the ground terminal needs to be corrected by Point Ahead Angle(PAA) so that the transmitted light reaches the expected location of the satellite. In this paper, we present the algorithm for PAA estimation and control.

• 한국화재소방학회논문지
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• 제26권6호
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• pp.51-56
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• 2012

국제우주정거장에서 화재발생은 승선한 승무원들의 생명과 직접적으로 연관된 사안이므로 선실내부에서 언제든지 발생할 수도 있는 화재의 초기 감지 및 진화는 우주정거장의 운영에 있어서 중요한 기술 중 하나이다. 본 연구에서는 국제우주정거장에서 각종 실험과 연구를 진행하는 가압모듈을 대상으로 환기, 연기거동 및 감지에 관한 수치모델링을 수행하였다. 수치모델링은 NIST에서 개발된 FDS(Fire Dynamic Simulator)를 사용하였으며, 부력이 작용하지 않는 국제우주정거장 내부의 무중력환경에서 발생된 화재의 연기거동패턴은 지상에서의 현상들과 큰 차이가 있음을 확인할 수 있었다. 아울러 가압모듈에서 적용되고 있는 환기조건을 고려하여 수행된 연기거동 및 감지특성에 대한 수치 모델링 결과는 향후 무중력환경에 노출된 수 있는 우주선이나 대형우주구조물의 화재검출장비의 설계를 위한 기초적인 자료를 제공함은 물론 승선하게될 우주인이나 승무원들의 훈련자료로도 유용하게 쓰일 수 있을 것으로 기대된다.