• Tribology and Lubricants
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• 제10권4호
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• pp.69-74
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• 1994

The space world under zero gravity and super vacuum where the space machine works has only friction and inertia. Inertia of acceleration and diceleration is accurately obtained by computing while friction is always in contact surface and unsteady. The sur soundings under super vacuum make surface friction more complicate. [1,2]. Therefore, method to lubricate stably the contact surface for long term in space machine is very important and friction for space machine proves to be true by several accident of space projects. In spite of that accident, method of lubrication and lubricants to keep stablity for long term in space machine have not been established so far. Lubrication for space machine is very important and under developings over the world. In this study we suggest a new lubricating technology, which improves powerful for space machine.

• 대한지리학회지
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• 제44권3호
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• pp.301-322
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• 2009

본 논문은 국지적 이동성의 도시 기계 공간인 지하철 공간의 기호적 재현을 공간, 시간, 장소의 의미에서 탐구한다. 제2절은 기존 연구에서 제시된 이동성의 도시 공간의 전반적 특징을 '기계 공간', '(비-)장소', '인지 지도'의 개념을 중심으로 검토한다. 제3절은 대구 지하철 공간에 대한 '공간적' 및 '시간적' 재현의 기호들을 해석하고, 그 기호적 재현의 의미를 제시한다. 이를 통해 지하철 공간에 상호 조화적으로 혹은 모순적으로 공존하는 기호 경관들이 그 공간을 다중적, 복합적인 기술-사회 공간으로 생산한다는 것을 밝힌다. 지하철 공간의 공간적-시간적 재현은 한편으로는 '(비-)장소', 다른 한편으로는 '장소'의 공간을 형성하며 또한 한편으로는 '기억', 다른 한편으로는 '망각'의 공간화를 수반한다. 지하철 공간은 사람들이 이동하는 '이동성' 의 공간만이 아니라 기계 및 도시 공간을 바라는 방식에 영향을 주는 '정체성'의 공간으로 생각되어야 한다.

• Journal of the Optical Society of Korea
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• 제15권4호
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• pp.394-397
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• 2011

For the purpose of fabricating off-axis aspheric optics, we propose an 8-axis-polishing machine combined with a testing tower whose height is up to 9 m. The proposed polishing machine was designed and analyzed by using a well-known finite element method. The eight axes of the machine have a synchronized motion generated by a computer, and each axis was calibrated by a heterodyne laser interferometer or an optical encoder. After calibration, the maximum positioning error of the machine was less than 2 ${\mu}m$ within a whole 2 m ${\times}$ 2 m area. A typical fabrication result of a ${\phi}1.5$ m concave mirror was also described in this manuscript.

• 한국정밀공학회지
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• 제13권1호
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• pp.98-107
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• 1996

The use of composite hyperpatch model is proposed to predict a machine tool positional error over the entire work space. This is an appropriate representation of the distorted work space. This model is valid for any configuration of 3-axis machine tool. Tool position, which is given NC data or CL data, contains error vector in actual work space. In this study, off-line compensation scheme was investigated for tool position error due to inaccuracy in machine tool structure. The error vector in actual work space is corrected by the error model using Newton-Raphson method. The proposed error compensation method shows the possibility of improving machine accuracy at a low cost.

• 산업공학
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• 제12권1호
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• pp.10-18
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• 1999

Job shop manufacturing environments are using the concept of cellular manufacturing systems(CMS) which has several advantages in reducing production lead times, setup times, work-in-process, etc. Utilizing the similarities between cell-machine, part-machine, and the shape/size of parts, CMS can group machines and parts resulting in improved efficiency of this system. However, when grouping machines and parts in machine cells, there inevitably occurs exceptional elements(EEs), which can not operate in the same machine cell. Minimizing these EEs in CMS is a critical point that improving production efficiency. Constraints in machine duplication cost, machining process technology, machining capability, and factory space limitations are main problems that prevent achiving the goal of maintaining an ideal CMS environment. This paper presents an algorithm that minimizes EEs under the constraints of machine duplication cost and factory space limitation. Developing exceptional operation similarity(EOS) by cell-machine incidence matrix and part-machine incidence matrix, it brings the machine cells that operate the parts or not. A mathematical model to minimize machine duplication is developed by EOS, followed by a heuristic algorithm in order to reflect dynamic situation resulting from minimizing exceptional elements process and the mathematical model. A numerical example is provided to illustrate the algorithm.

• Journal of international Conference on Electrical Machines and Systems
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• 제1권3호
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• pp.303-311
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• 2012

An innovative interpretation of the per-unit interior permanent magnet (IPM) machine model known as Design Space is presented in this paper. Based on the proposed Design Space formulation, an effective computation method to predict IPM machine performance factors, such as the current and power factor in a full range of speeds, is proposed. A systematic methodology is summarized, which translates the full speed range machine design procedure into the region determination on the so-called Design Space. The effect of dc-link voltage is also analyzed in a similar manner with the current and power factor. A series of IPM motors have been designed, and a preferred motor is selected with the help of the proposed Design Space Methodology (DSM), which has the best tradeoff between the nominal voltage and the dropped voltage condition. Experiment results show that the selected motor satisfies the machine requirements and all the design constrains, such as the current and back-EMF limitations.

• 산업공학
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• 제12권4호
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• pp.617-624
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• 1999

In order to maximize an availability of machine and utilization of space, the parallel machines scheduling problem with space limit is frequently discussed in the industrial field. In this paper, we consider a scheduling problem for assembly machine in ship engine assembly shop. This paper considers the parallel machine scheduling problem in which n jobs having different release times, due dates and space limits are to be scheduled on m parallel machines. The objective function is to minimize the sum of earliness and tardiness. To solve this problem, a heuristic is developed. The proposed heuristic is divided into three modules hierarchically: job selection, machine selection and job sequencing, solution improvement. To illustrate its effectiveness, a proposed heuristic is evaluated with a large number of randomly generated test problems based on the field situation. Through the computational experiment, we determine the job selection rule that is suitable to the problem situation considered in this paper and show the effectiveness of our heuristic.

• Industrial Engineering and Management Systems
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• 제11권1호
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• pp.26-29
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• 2012

In order to deal with the classification problems of type-2 fuzzy training samples on generalized credibility space. Firstly the type-2 fuzzy training samples are reduced to ordinary fuzzy samples by the mean reduction method. Secondly the definition of strong fuzzy linear separable data for type-2 fuzzy samples on generalized credibility space is introduced. Further, by utilizing fuzzy chance-constrained programming and classic support vector machine, a support vector machine based on type-2 fuzzy training samples and established on generalized credibility space is given. An example shows the efficiency of the support vector machine.

• 한국실내디자인학회논문집
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• 제16권2호
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• pp.131-138
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• 2007

Relationship between body and space is fundamental in space design. The perception and concept of human body in each age directly affected the space makings of that time. Thoughts on human body are related to various periodical backgrounds such as culture, art, technology and etc. Body-Space relationship has been changed through different epochs and is being changed in the present time too. In contemporary cities, architectural programs has been fragmented and activities of individuals become more articulated. The rigidity of each architectural program has been forced to be more flexible amalgamation of diverse behaviors by dynamic urban time-space formations and patterns. Based on this current situations, new experimental designs that question the existing preconceived relationship between body and space in different views. These design experiments attempt to overcome the solid physical fixation of architectural buildings and to directly relate human body to intelligent devices, technologies, machines as well as spaces. This research focus on the innovative design projects in which body, machine, space are smartly compound as one organization. The purpose of this study is to examine the new Body-Space relationship as well as some relevant case projects in contemporary fashion, furniture, interior design and architecture.

• 천문학회보
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• 제43권1호
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• pp.40.3-40.3
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• 2018

We present results from our two experiments of using machine learning algorithms in processing and analyzing the KMTNet imaging data. First, density estimation and clustering methods find meaningful structures in the metric space of imaging quality measurements described by photometric quantities. Second, we also develop a method to separate out light curves of reliable microlensing event candidates from spurious events, estimating reliability scores of the candidates.