• ETRI Journal
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• 제34권4호
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• pp.518-526
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• 2012

This paper proposes LC voltage-controlled oscillator (VCO) phase-locked loop (PLL) and ring-VCO PLL topologies with low-phase noise. Differential control loops are used for the PLL locking through a symmetrical transformer-resonator or bilaterally controlled varactor pair. A differential compensation mechanism suppresses out-band spurious tones. The prototypes of the proposed PLL are implemented in a CMOS 65-nm or 45-nm process. The measured results of the LC-VCO PLL show operation frequencies of 3.5 GHz to 5.6 GHz, a phase noise of -118 dBc/Hz at a 1 MHz offset, and a spur rejection of 66 dBc, while dissipating 3.2 mA at a 1 V supply. The ring-VCO PLL shows a phase noise of -95 dBc/Hz at a 1 MHz offset, operation frequencies of 1.2 GHz to 2.04 GHz, and a spur rejection of 59 dBc, while dissipating 5.4 mA at a 1.1 V supply.

• 한국치위생학회지
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• 제19권6호
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• pp.1067-1075
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• 2019

Objectives: The present study aimed to compare the accuracy of removable partial denture (RPD) frameworks fabricated by selective laser sintering (SLS) before and after electropolishing. Methods: A partially edentulous mandibular model was used as the working model. Scanning of the model was performed using a dental scanner. The framework was designed using CAD software. The metal framework was formed using an SLS 3D printer. 3D scans of the two fabricated prototypes produced before and after electropolishing were overlapped with reference data. The fit was calculated based on Root Mean Square (RMS). Fabrication accuracy was verified using the paired t-test to compare the discrepancy before and after electropolishing. Results: The mean (SD) values of RMS before and after electropolishing were 126.6 (34.19) and 75.86 (21.36), respectively. There was a statistically significant difference before and after electropolishing (p<0.05). Conclusions: Metal frameworks made with SLS 3D printers showed clinically acceptable fit after electropolishing.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2018년도 춘계 학술논문 발표대회
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• pp.294-295
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• 2018

Nowadays, the construction industry utilizes 3D models in the designing process, on which research is being conducted to establish an automated system for project cost estimation in connection with information related to construction such as material unit costs and wages, beyond the level of design interference review and construction quantity estimation. In this process, the project cost is estimated in connection with unit price data after takeoff the quantity based on the 3D model attributes and data types. A way to reduce cost and risk would be first developing prototypes of some of essential buildings and works, comparing and validating the outcomes, and then extending to the whole scope, because estimates differ on the basis of the scope and level of 3D design models as well as the data accuracy. This study analyzes case studies of project cost estimation by computing the quantity on the basis of 3D model in the construction industry and explores methodologies and management measures applicable for estimating nuclear power plant construction project costs.

• 한국생산제조학회지
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• 제24권3호
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• pp.334-341
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• 2015

This paper summarizes the results of an investigation into the environmental factors that have an indirect impact on parts quality, as well as those process variables and modeling information that have a direct impact. The effects of strength, surface hardness, roughness, and accuracy of shape, that is, qualities that users generally need to know, were evaluated with laminating direction experimentally. The 3D printing methods used in this experiment were fused deposition modeling (FDM), stereolithography apparatus (SLA), selective laser sintering (SLS), 3D printing (3DP) and laminated object manufacturing (LOM). The goal was to achieve a high standard of quality control and product quality by optimizing the fabrication process.

• 한국의류산업학회지
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• 제13권4호
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• pp.614-623
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• 2011

The purpose of this study is to develop a wedding dress basic torso pattern and sleeve pattern considering good fit and aesthetic for figures of Korean brides in their 20s. For the research method, 3 women in their 20s who has the body size of ${\pm}$ S.D range of average figure and dress form suggested by 'the 5th human body measurement' of Size Korea were selected as the test group. The evaluators are 8 clothing construction majors, and the evaluation items included total 22 questions related to torso and total 10 questions related to sleeves. The evaluation was made using 5 Likert point scale. 4 prototypes for basic dress pattern were selected through the literature search. After compare analyzing design methods of prototypes, the real wedding dresses were made in the average size of women in their 20s and the dresses were tried on for the assessment. The data was analyzed using SPSS 18.0 Program to examine average, standard deviation and significant differences between basic patterns. Based on the results of the first and the second try-on assessments, a new wedding dress basic pattern with maximized strengths of compared prototypes was completed. The details of result follows. As for dress torso basic pattern, A pattern, which had the highest overall silhouette satisfaction and scores in basic pattern analysis and try-on assessments, was selected as the prototype, and a research basic pattern reflecting strengths of each basic pattern was developed. As for dress sleeve basic pattern, B pattern, which had the highest overall silhouette satisfaction and scores in basic pattern analysis and try-on assessments, was selected as the prototype, and a research basic pattern reflecting strengths of each basic pattern was developed. In this study, a wedding dress basic pattern considering good fit and aesthetic for figures of Korean brides in their 20s was suggested. It is expected that the basic pattern will be used by continuously developing dress market and ready-made wedding dress manufacturers as well as in educational institutes.

• 디지털융복합연구
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• 제19권3호
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• pp.331-344
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• 2021

본 연구의 목적은 우리가 일상에서 사용하고 있는 식생활 도구인 젓가락의 디자인에 대해 살펴보고, 획일화되고 한정된 우리의 금속젓가락 디자인을 지양하여 식탁의 미학을 더할 디자인으로의 향상을 꾀하고자 3D 모델링 시스템의 활용 가능성을 모색하는 데 있다. 이를 위해, 연구자는 한국의 문화요소를 디자인의 조형요소로 활용하는 가운데 3D 모델링을 이용한 섬세한 표현을 통해 독창적인 문화콘텐츠가 될 수 있도록 시제품을 제작하였다. 제작 결과, 한국의 특성을 지닌 개성 있는 젓가락 디자인을 도출할 수 있었다. 이러한 시제품의 사례와 같이 3D 모델링과 3D 프린팅은 젓가락 디자인의 새로운 탐색에 도움을 줄 수 있을 것이며, 다양한 시뮬레이션을 통해 디자인의 향상과 품질을 개선시킬 수 있을 것이다. 또한 한국의 문화상품으로서의 역할을 할 수 있는 문화콘텐츠 개발에 도움이 될 것이다.

• 한국정밀공학회지
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• 제25권1호
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• pp.122-129
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• 2008

Two-photon stereolithography is recognized as a promising process for the fabrication of three-dimensional (3D) microstructures with 100 nm resolution. Generally, beam-scanning system has been used in the conventional process of two-photon stereolithography, which is limited to the fabrication of micro-prototypes in small area of several tens micrometers. For the applications to 3D high-functional micro-devices, the fabrication area of the process is required to be enlarged. In this paper, large-area two-photon stereolithography (L-TPS) employing stage scanning system has been developed. Continuous scanning method is suggested to improve the fabrication speed and parameter study is conducted. An objective lens of high numerical aperture (N.A.) and high strength material were employed in this system. Through this work, 3D microstructures of $600*600*100\;{\mu}m$ were fabricated.

• 한국항행학회논문지
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• 제18권2호
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• pp.191-199
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• 2014

최근 IT 분야의 화두인 클라우드 컴퓨팅과 빅데이터 패러다임을 중소기업(Small and Medium Business: SMB) 차원에서 용이하게 활용하도록 지원하는 시도가 증가하고 있다. 이러한 노력의 일환으로, 본 논문에서는 프라이빗 클라우드 인프라 환경을 대상으로 하둡(Hadoop) 클러스터를 시험적으로 구축하는 프로토타입을 설계하고 구현한다. 프로토타입 구현은 싱글보드, PC, 그리고 서버를 이용하여 각각 수행하고, 그 성능을 테스트한다. 또한, ASA (American Standard Association) Dataset을 이용한 빅데이터 분석을 통해서 구축된 하둡 프로토타입을 활용하는 분석 소프트웨어 시스템의 성능을 통합적으로 검증한 결과를 제시한다. 이를 위해, R, 파이썬, D3, 자바와 같은 오픈소스를 이용하여 분석 소프트웨어 시스템을 구현하고, 테스트를 수행한다.

• Journal of electromagnetic engineering and science
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• 제13권1호
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• pp.8-15
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• 2013

This paper presents a novel design for a simple rectangular ring with an open-ended monopole antenna that is well suited to DCS/PCS/UMTS/WLAN applications for dual-band operations. A microstrip-fed rectangular monopole antenna is first designed and then modified to introduce the rectangular ring with an open-ended antenna and a rectangular slit in the ground plane. Prototypes of the proposed antenna were fabricated and tested. The antenna, resonating at 1,405 MHz and 4,840 MHz, has a -10 dB impedance bandwidth of about 1,695 and 1,530 MHz (1,220~2,815 and 4,495~6,025 MHz), or about 79.06 % and 29.09 %. The observed 2D radiation patterns and 3D gain performance of the antenna in the operation bands are discussed.

• Journal of information and communication convergence engineering
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• 제10권4호
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• pp.321-328
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• 2012

A novel design for a simple rectangular ring with open-ended monopole antenna wireless local area network (WLAN) applications is proposed in this article. The proposed antenna consists of an open-ended rectangular ring, an inverted L-strip, and a rectangular slit in the ground plane, and is fed by a 50 ${\Omega}$ microstrip feed-line. Prototypes of the proposed antenna were designed, fabricated, and tested. Experimental results show that the proposed antenna receives 2.3125-2.775 GHz and 4.8625-6.7125 GHz with a return loss less than -10 dB, covering the required bandwidths of the 2.4/5.2/5.8 GHz WLAN standards. Meanwhile, the 2D radiation patterns and 3D gain performance of the antenna in the operation bands were also observed and discussed.