• 한국산학기술학회논문지
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• 제18권1호
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• pp.287-294
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• 2017

국내 AEC 산업 분야에 2000 년대 중반부터 그 적극적인 도입이 시작된 BIM 기술은 최첨단 건축, 초대형 건축, 비정형 건축 등을 중심으로 그 도입이 가속화 되어 왔다. 건물 구축 기술의 부족으로 의해 완공률이 낮았던 비정형 건축물들이 BIM 기술의 도입으로 많은 구축 성공 사례가 생기면서 건축가들이 비정형 건축 설계에 활발히 도전하고 있다. 그러나 비정형 설계가 가능한 모델러들은 설계, 시공, 유지관리 등에서의 데이터 관리가 효율적인 BIM 데이터의 구축이 어렵다. 그러므로 본 연구에서는 비정형 모델러에서 생성된 건축 부재 데이터의 BIM 데이터로의 변환 프로세스를 제안하였다. 제안된 프로세스 모델은 비정형 건축 부재를 형성하기 위한 형성 조건 수신부, 건축부재 생성부, 그리고 BIM 데이터 생성부 세가지 부분으로 구성된다. 구체적으로는 NURBS 기반 모델러에서 비정형 슬라브, 기둥, 보 파라메트릭 건축 부재 형성과 BIM 도구로의 데이터 전이 및 BIM 건축 부재 데이터 형성을 위한 프로세스 모델을 제안하며, 이를 실현하기 위한 프로토타입 시스템이 구현되었다.

• Journal of the Optical Society of Korea
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• 제20권5호
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• pp.614-622
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• 2016

In this paper, we propose a novel differential equation method for designing a total internal reflection (TIR) LED lens with double freeform surfaces. A complete set of simultaneous differential equations for the method is derived from the condition for minimizing the Fresnel loss, illumination models, Snell’s Law of ray propagation, and a new constraint on the incident angle of a ray on the light-exiting surface of the lens. The last constraint is essential to complete the set of simultaneous differential equations. By adopting the TIR structure and applying the condition for minimizing the Fresnel loss, it is expected that the proposed TIR LED lens can have a high luminous flux efficiency, even though its beam-spread angle is narrow. To validate the proposed method, three TIR LED lenses with beam-spread angles of less than 22.6° have been designed, and their performances evaluated by ray tracing. Their luminous flux efficiencies could be obviously increased by at least 35% and 5%, compared to conventional LED lenses with a single freeform surface and with double freeform surfaces, respectively.

• 한국산학기술학회논문지
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• 제14권9호
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• pp.4616-4626
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• 2013

디지털 기술의 급속한 발전과 함께 비정형 건축은 그 실현가능성을 높여 왔으며, 비정형 형태로 계획된 복잡한 형태의 건축 외피를 성공적으로 구축하기 위한 패널분할과 최적화 기법 연구에 대한 필요성이 증가하고 있다. 본 논문은 비정형 건축곡면의 성공적인 구축을 위한 선행과제로서 비정형 곡면과 건축곡면 패널분할 기법을 통합적 관점에서 재분류하고 명확한 개념정립을 제시하였으며, 패널분할 최적화 기법의 유형 분류와 유형별 특징 및 사례를 연구하였다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.73-77
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• 2004

This paper presents a PC-based controller of industrial SFFS(Solid Freeform Fabrication System). The SFFS has multiple sub-controllers for the building room, the powder room, the temperature, and the density of oxygen in the chambers. Hence the main PC-based controller should effectively and timely send commands to the sub-controllers, and monitor the overall SLS process. The required actuators and sensors are selected to optimize the overall performance of the SFFS.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1998년도 추계학술대회 논문집
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• pp.13-18
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• 1998

The assessment of machined surface is difficult because the freeform surface must be evaluated by surface fairness as well as dimensional accuracy. In this paper, the methodology of freeform surface generation using measured data on the machine tool is presented. The reliability of measured points data is obtained by measuring error compensation. The compensated data are formulated through Non-uniform G-spline surface modeling. In order to improve the surface fairness, the generated model si smoothened by parameterization The validity and usefulness of the proposed method are examined through computer simulation and experiments on the machine tool.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 하계종합학술대회 논문집(5)
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• pp.91-94
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• 2002

SFFS(Solid Freeform Fabrication System) is commercializing to rapid prototyping concept in foreign some corporations including the U.S.A, have much technological problems yet and need new mode for agile prototyping. In this paper, we design algorithm that the cutting path of laser beam, on the SFFS(Solid Freeform Fabrication System), is controlled with constant speed. The designed algorithm for constant-speed path control is implemented and experimented in the CAFL$\^$VM/ (Computer Aided Fabrication of Lamination for Various Material) system, the new SFFS which was developed in this paper.

• 대한기계학회논문집A
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• 제32권7호
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• pp.602-609
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• 2008

This paper presents experimental optimization of process parameters for a newly developed SFF(Solid Freeform Fabrication) system. Two critical process parameters, layering thickness and curing period, which have a large effect on the quality of the product, are optimized through experiments. Specimens are produced using layering thicknesses of 60, 80, 100, 120, 140, and $160\;{\mu}m$ and curing periods of 0, 10, 20, and 30 minutes under the same processing conditions, i.e., build-room temperature, feed-room temperature, roller speed, laser power, scan speed, and scan spacing. The specimens are tested to compare and analyze performance indices such as thickness accuracy, flatness, stress-strain characteristics, and porosity. The experimental result indicates that layering thickness of $80{\sim}100\;{\mu}m$ and curing period of $20{\sim}30$ minutes are recommended for the developed industrial SFF system.

• 한국산학기술학회논문지
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• 제13권9호
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• pp.4259-4265
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• 2012

본 논문은 최근 국내 비정형 건축설계에 적용된 디지털 기술들과 기술 적용과정에서 도출된 문제점 등을 분석함을 그 목적으로 하며, 이를 위하여 세 개의 국내 비정형 건축 사례를 선정하여 전문가 인터뷰와 문헌조사를 통하여 비정형 설계 및 시공을 위하여 적용된 디지털 기술들을 분석하였다. 그 결과 비정형 곡면을 위한 패널 최적화의 필요성, 파일 호환성 확보의 중요성, 비정형 건축의 복잡한 형상으로 인한 시공성 확보의 어려움, 패널 부재제작시 3D 데이터 수용의 어려움이 발견되었으며, 도출된 문제점에 대한 사례별 해결방안을 분석하여 보았다.

• Current Optics and Photonics
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• 제1권3호
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• pp.233-238
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• 2017

In this paper we propose a freeform secondary lens for an LED fishing/working lamp (LFWL). This innovative LED lamp is used to replace the traditional HID fishing lamp, to satisfy the lighting demands of fishing and the on-board activities on fishing boats. To realize the freeform lens's geometry, Gaussian decomposition is involved in our optics-design process for approaching the targeted light intensity distribution curve (LIDC) of the LFWL lens. The simulated results show that the illumination on the deck, on the sea's surface, and underwater shows only small differences between LED fishing/working lamps and HID fishing lamps. Meanwhile, a lighting efficiency of 91% with just one third of the power consumption can be achieved, when the proposed LED fishing/working lamps are used instead of HID fishing lamps.

• 한국CDE학회논문집
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• 제16권2호
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• pp.126-136
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• 2011

The existing approaches to freeform building construction cause many problems. However, recent BIM technique development based on parametric modeling method and improvement of freeform materials manufacturing technology using IT technology encouraged many advanced countries to try experimental projects. Thus, laser scanning technique is in the limelight as a new alternative in the field of freeform building construction and inspection. This study selected a domestic small freeform building and practiced laser scanning and as-planned modeling by using Reverse Engineering. Then each deviation was comparatively analyzed through figures which extracted data by numerically analyzing the newly modeled as-built and Excel spread sheet. Through the process, limits and follow-up research subjects are discussed as well.