• International Journal of Precision Engineering and Manufacturing
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• 제3권4호
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• pp.15-23
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• 2002

With the development of a laser scanner of high precision and increased speed, reverse engineering becomes a key approach to reduce the time for the development of new products. But the modeling process is not so automated enough until now. Modeling in real workshops is usually performed by the experienced operators and it requires a skillful technique to get the resultant surface of high quality and precision. In this paper, a systematic solution is proposed to automate the free-form surface generation from the measured point data. Compatibility is imposed to the measured point data during input curve generation. And the compatibility of cross-sectional curve is also considered for the loft surface generation. The data in each step is produced in IGES file format to make an easy interface to other CAD/CAM software without any further data manipulation.

• 한국CDE학회논문집
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• 제14권3호
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• pp.197-206
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• 2009

In a finite element analysis of the metal forming processes having large plastic deformation, largely distorted elements are unstable and hence they influence upon the result toward negative way so that adaptive remeshing is required to avoid a failure in the numerical computation. Therefore automatic mesh generation and regeneration is very important to avoid a numerical failure in a finite element analysis. In case of generating quadrilateral mesh, the automation is more difficult than that of triangular mesh because of its geometric complexity. However its demand is very high due to the precision of analysis. Thus, in this study, an automatic quadrilateral mesh generation and regeneration method using grid-based approach is developed. The developed method contains decision of grid size to generate initial mesh inside a two dimensional domain, classification of boundary angles and inner boundary nodes to improve element qualities in case of concave domains, and boundary projection to construct the final mesh.

• 한국정밀공학회지
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• 제21권3호
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• pp.83-90
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• 2004

This paper proposes a tool path generation method for machining impellers with 5-axis machining center. The shape of impeller is complex, being composed of pressure surface, suction surface and leading edge, and so on. The compound surface which is made of ruled surface such as pressure surface and suction surface and leading edge such as fillet surface, makes the tool path generation much complicated. To achieve efficient roughing, cutting area is divided into two region and then tool radius of maximum size that do not cause tool intereference is selected for shortening machining time. In finishing, accuracy is improved using side cutting for blade surface and point milling for leading edge.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 하계종합학술대회 논문집(1)
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• pp.21-24
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• 2000

In this paper, We introduce effective handoff method from W-COMA system of 3$^{rd}$ generation to 15-95 system of 2$^{nd}$ generation. In case of this handoff, Ms should know long code state using traffic channel, timing information and pilot offset of 26 synchronous system during the compressed mode. So We establish additional common channel in order to obtain handoff information. Common channel transmits same information from all base stations and provides MS with timing information of zero offset. long code state and timing of super frame for sync. channel. Therefore during the compressed mode. MS can obtain information for handoff using common channel..

• IEIE Transactions on Smart Processing and Computing
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• 제5권3호
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• pp.185-192
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• 2016

Today, the Internet has penetrated almost all the ins and outs of social life, has changed work, communications, social influence and the lifestyle of humankind. However, it is still short of flexibility, transparency etc., due to network address translator overuse, masschanges, uncomfortable protocols, and so on. Hence, more research is necessary into future telecommunications networks based on contemporary networks accompanied by new requisitions and new designs that are compatible with today's and tomorrow's demands. This paper researches a new vision of the telecommunication network of the future, its effects on human life and society, and the targets to achieve a new generation network (NwGN). In the paper, we also propose orientation towards an NwGN from the current networks, especially with Vietnam's telecommunications networks.

• 대한기계학회논문집
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• 제18권12호
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• pp.3159-3174
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• 1994

A simple octree encoding algorithm based on a tetrahedron root has been developed to be used for fully automatic generation of three dimensional finite element meshes. This algorithm starts octree decomposition from a tetrahedron root node instead of a hexahedron root node so that the terminal mode has the same topology as the final tetrahedral mesh. As a result, the terminal octant can be used as a tetrahedral finite element without transforming its topology. In this part(I) of the thesis, an efficient algorithm for the tetrahedron-based octree is proposed. For this development, the following problems have been solved, : (1) an efficient data structure for storing the octree and finite elements, (2) an encoding scheme of a tetrahedral octree, (3) a neighbor finding technique for the tetrahedron-based octree.

• 한국전기전자재료학회논문지
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• 제31권3호
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• pp.182-187
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• 2018

In this study, 20.8% of a p-type Si bifacial solar cell was used to develop a photovoltaic (PV) module to obtain the maximum power under a limited installation area. The transparent back sheet material was replaced during fabrication with a white one, which is opaque in commercial products. This is very beneficial for the generation of more electricity, owing to the additional power generation via absorption of light from the rear side. A new model is suggested herein to predict the power of the bifacial PV module by considering the backside reflections from the roof and/or environment. This model considers not only the frontside reflection, but also the nonuniformity of the backside light sources. Theoretical predictions were compared to experimental data to prove the validity of this model, the error range for which ranged from 0.32% to 8.49%. Especially, under $700W/m^2$, the error rate was as low as 2.25%. This work could provide theoretical and experimental bases for application to a distributed and microgrid network.

• 디자인학연구
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• 제13권3호
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• pp.39-48
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• 2000

본 연구는 제품 디자인 프로세스중 아이디어나 디자인의 가능성에 대하여 탐색하는 부분을 중심으로 디자인 목표가 명확하게 정해지지 않은 상황하에서 1. 시각적으로 형태발상 지원시스템을 구축하여 디자이너에게 형태발상 능력의 한계를 극복할 수 있도록 지원하고, 2. 또한 사용자 참여적 형태발상 시스템으로서 웹 상에서 사용자들의 요구에 실시간으로 다이나믹하게 이미지를 생성해주고 사용자들의 선호도를 분석하여 선호도가 높은 이미지에 대한 정보를 디자이너에게 제공하는 즉 디자이너가 사용자들의 의견을 수렴할 수 있도록 하고, 3. 선호도가 낮은 이미지들은 누락시키고 지속적으로 새로운 이미지 조합을 업데이트하여 사용자의 형태 및 칼라에 대한 선호추세를 파악하여 미래에 선호될 수 있는 칼라와 이미지를 생성할 수 있도록 하였다. 이는 제품 디자인 개발 프로세스 중 아이디어발상 또는 형태 발상 지원에 대한 한 방식으로 그 효과가 있으리라 기대된다.

• 한국잠사곤충학회지
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• 제23권1호
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• pp.32-37
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• 1981

누에의 人工飼科는 物理的 또는 化學的으로 뽕잎과는 그 性質이 매우 다르기 때문에 고치 生産性에 있어서 뽕잎의 경우 보다 不良한 成績인데 이 欠點을 解決하기 위하여는 우선 人工飼科에 適合한 品種이 育成되어야 한다. 그러므로 本試驗에서는 人工飼科育에 의하여 優良系統을 選拔했을 때에 發生하는 現象을 究明코저 遂行하였으며 그 結果는 다음과 같다. 1. 암고치의 繭層重과 繭層比率과의 相關關係는 Sa와 Y에서는 없다. 2. 숫고치에서 Sa系統의 全繭重과 繭層比率과는 相關關係가 없다. 3. 人工飼科育에 있어서 日本種系統과 中國種系統은 각각 選拔效果가 特異하게 나타났다. 4. 桑葉育에서 人工飼科育으로 전환하는 第1世代에서는 Sa와 Y系統이 모두 매우 不良한 成績을 나타냈으나 第 2, 3世代에서 急激하게 증가하여 選拔效果는 매우 컸다. 5. 第 4 世代에서는 致死率이 매우 높았기 때문에 第 5世代는 桑葉育으로 繼代 增殖하였다. 6. 第 6 世代에서 10世代까지 選拔效果는 계속 증가하였는데 繭層比率만은 例外이었다.

• 한국도서관정보학회지
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• 제44권3호
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• pp.471-488
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• 2013

본 연구는 우리나라 대학도서관별 차세대 OPAC 기능 수용 현황을 파악하고, 기능의 수용에 영향을 미치는 요인을 고찰하고자 하였다. 이를 위해 차세대 OPAC 기능 27개로 구성된 체크리스트를 사용하여 191개 대학도서관 중 접속 가능한 181개 대학도서관의 OPAC을 조사하였다. 조사된 도서관의 차세대 OPAC 기능 수용은 SPSS Statistics 21을 사용하여 운영주체, 설치지역, 총예산, 장서량, 이용대상자수, 그리고 도서관자동화시스템 등의 변수와 상관관계를 분석하였다. 세부적인 기능 간에 약간의 차이가 있었지만 대학의 운영주체 변수를 제외한 모든 변수가 차세대 OPAC 기능의 수용에 유의한 영향을 미치는 것으로 나타났으며 각 요인에 대한 세부적인 분석이 이루어졌다.