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Development of High-Performance, Low-Cost 3D Printer Using LCD and UV-LED
조광호(Kwang Ho Jo),장현석(Hyeon Suk Jang),하영명(Young Myoung Ha),이석희(Seok Hee Lee) Korean Society for Precision Engineering 2015 한국정밀공학회지 Vol.32 No.10
3D Printing has a great advantage for its capabilities in manufacturing complicated structures in a reasonable manufacturing time, and thus is widely used in various fields. Due to the high cost of the equipment and material, a fairly acceptable equipment, the Projection Stereolithography Apparatus (PSLA), has been developed, using the projection pattern approach for the purpose of quick manufacturing. We evaluated its surface quality, as compared with that of other systems. The result is the development of a high-performance, low-cost 3D Printer and its operating software, using LCD and UV LED. Working materials for an optimal manufacturing are suggested in the research, along with some suggestions of basic approaches for enhancing the accuracy and quality of the manufactured structures.
전사방식 마이크로 광 조형에서 복합 재료의 미세구조물 제작을 위한 수지 교환 시스템 개발
조광호(Kwang Ho Jo),박인백(In Baek Park),하영명(Young Myoung Ha),김민섭(Min Sub Kim),이석희(Seok Hee Lee) Korean Society for Precision Engineering 2011 한국정밀공학회지 Vol.28 No.8
For enlarging the applications of microstereolithography, the use of diverse materials is required. In this study, the material switching system (MSS) for projection microstereolithography apparatus is proposed. The MSS consists of three part; resin level control, resin dispensing control, and vat level control. Curing characteristic of materials used in fabrication has been identified. Through repeated fabrication of test models, the critical fabrication error is investigated and a possible solution to this error is suggested. The developed system can be applied to improve the strength of microstructure and extended to fabricate an array of microstructures with multiple materials.
문화적 장소특성 구축의 최근 동향 분석을 통한 원도심 재생방안 연구
조광호(Jo, Kwang-Ho),이선영(Lee, Sun-Young) 대한건축학회 2016 대한건축학회논문집 Vol.32 No.8
The purpose of this study aims to identify about old downtown regeneration and activation trends through culture. To do this, we figure out about general concept and concept of the old downtown through culture. In addition, to analyze about local examples of old downtown regeneration based on culture in terms of establishing place, program planning, human resources, and identify with characteristics of cultural urban regeneration and recent trend. Project is pursued establishing place actively utilized spare space in the old downtown, these spare spaces have a distribution relationship between the type of space being used and the size of the unit area. Recently it has been found showing diversified aspects of space supporting such as purchase, lease, rental payment. In addition, old downtown"s regeneration business based on culture networking thorough local cultual governance for old downtown regeneration of based on culture are reworking. Shared-values programs that culture_art sympathy and effect with society on Program planning are working and citizen-oriented programs phase in, activation also figure out seeking to complex genre based on diversity of field. Finally, leading local public cultural institutions and cultural organizations focusing on human resources and the participation of local youth as cultural workers and creative talent that resides in the current area stand out.
조철현,정현기,조광호,Jo, Churl-Hyun,Chung, Hyun-Key,Cho, Kwang-Ho 한국구조물진단유지관리공학회 1999 한국구조물진단유지관리공학회 논문집 Vol.3 No.2
There is an increasing need for the estimation of foundation piles whose depths are unknown. Especially in repair and reinforcement works or in safety inspection and assessment to the big structures whose foundations are piles, the accurate information about the depth of foundation piles is one of the most important factors. A borehole magnetic tool has been developed and tested to meet this object. The fundamental base is that there usually exist many re-bars inside the foundation structure such as piles, and these re-bars are ferromagnetic materials which cause strong induced magnetic field comparable to the earth magnetic field. It utilizes flux-gate type magnetometer which measures 3-components of the magnetic field. Taking vertical derivatives of vertical component of the measured magnetic field, we can expect the error limit of estimating the depth of the pile end less than 20 cm in favorable condition. The maximum measurable distance is about 3 m to the pile from the borehole. The field data show that borehole magnetics is one of the most accurate, fast, and reliable methods for this object so far, as long as there is no magnetic materials such as deep located steel pipe or power cables close to the foundation piles.
LCD와 가시광선LED 를 사용한 전사방식의 Scanbeam-SLA 개발
윤수현(Su Hyun Yoon),박인백(In Baek Park),김민섭(Min Sub Kim),조광호(Kwang Ho Jo),이석희(Seok Hee Lee) Korean Society for Precision Engineering 2013 한국정밀공학회지 Vol.30 No.3
In Projection Stereolithography Apparatus (PSLA), Digital Micromirror Device (DMD) and Liquid Crystal Display (LCD) are used as a beam pattern generator. The DMD shows high resolution, but it is mostly applied in micro stereolithography due to high cost and fabricable area. In LCD, the size of pattern beam is freely controlled due to various panel sizes. The LCD, however, has some limitations such as short life time by the high power light source, non-uniform light intensity of pattern beam and low transmittance of UV-light. To solve these problems in LCD-based PSLA, a Scanbeam-SLA with LCD of 19 inches and visible LED-array is developed. In this system, the light module works like a scanner for uniform illumination. The system configuration, working principle and fabrication examples are addressed in this study.
박윤미(Yun?Mi Park),김선재(Seon?Jae Kim),조광호(Kwang?Ho Jo),양은정(Eun Jung?Yang),정순택(Soon?Teck Jung) 한국식품영양과학회 2006 한국식품영양과학회지 Vol.35 No.3
생약재를 이용하여 천연 자원에서 항충치와 항산화 물질을 탐색하고 부가가치를 높이고자 하였다. 41종의 생약재 20 g을 ethanol 300 mL에 추출하고 농축하여 전량을 20 mL로 하여 시료로 사용하였다. 생약재의 phenolic compound의 함량을 측정하였으며, phenolic compound의 함량은 tannic acid로 환산하여 나타냈다. 가장 많은 phenolic compound 함량은 측백으로 115.24 ㎍/mL이었으며, 목과, 토복령, 목단, 소엽, 팔각향이 각각 97.49 ㎍/mL, 97 ㎍/mL, 96.27 ㎍/mL, 96.56 ㎍/mL, 94.40 ㎍/mL이었다. Streptococcus mutans와 타액을 배양한 균주 5종에 대하여 생약재 ethanol 추출물로 항균성효과 실험을 하였다. 그 결과 Streptococcus mutans에서는 팔각향과 공사인이 98%로 높았으며, S-1과 S-2에서는 팔각향이 98%, 계피가 94%로 높은 항균효과가 있었다. S-3는 목과 95, S-4는 희첨 97%이었고, S-5에서는 연자육이 94%로 항균효과가 높았다. Streptococcus mutans와 타액을 배양한 균주 5종에서 glucosyltransferase(GTase) 효소를 분리하여 생약재에 의한 활성저해효과를 측정하였다. Streptococcus mutans의 GTase에서는 팔각향과 공사인이 94%로 활성저해효과가 가장 높았다. S-1에서 분리한 GTase에 대해서는 공사인이 95%로 효소활성 저해 효과가 가장 높았으며, S-2는 팔각향이 59%로 가장 높았다. S-4의 GTase는 목과가 96%이고, 작약과 팔각향이 95%였고, S-5의 GTase에서는 측백이 96%로 효소활성 저해효과가 높았다. 생약재들의 항산화성을 알아보기 위하여 DPPH radical scavenging를 알아보았으며, 시료는 100 ㎍/mL, 200 ㎍/mL, 300 ㎍/mL를 첨가하여 측정하였다. 시료 100 ㎍/mL에서 측백이 81.08 %로 항산화활성이 가장 높았으며, 토복령, 계피가 각각 80.45%, 76.63%로 항산화활성이 높았다. 시료 300 ㎍/mL에서는 연자육이 82.79%로 가장 높았으며, 감초, 계피, 공사인, 목과, 목단, 소엽, 애엽, 인진, 정향, 지각, 창이자, 천초, 측백, 토복령, 헛개나무, 홍화자 등 또한 항산화활성이 높았다. 생약재 ethanol추출물 중 항충치, 항산화효과가 높은 생약재들은 대부분 많은 phenolic compound함량을 나타내고 있어 phenolic compound는 항충치 및 항산화효과에 관련이 있는 것으로 생각된다. We have tested 41 herbal medicines to search for a natural substance with antimicrobial activity against Streptococcus mutans and five types of oral bacteria. We have also investigated antioxidative activity of these herbal medicines. Antimicrobial activity against Streptococcus mutans and five types of oral bacteria was analyzed using ethanol extracts of herbal medicines. Extracts from Illicium verum and Amomum xanthioides showed 98% inhibitory activity against Sterptococcus mutans. The effect of Thuja orientalis on S?1 and Thuja orientalis and Amomum xanthioides on S?2 were 95% and 94%, respectively. Nelumbo nucifera was 94% effective on S?5. The inhibitory activities of the herbal medicines against glucosyltransferase (GTase) were determined using purified from Streptococcus mutans and five types of oral bacteria. Extract from Illicium verum and Amomum xanthioides showed 94% effectiveness on Streptococcus mutans. Amomum xanthioides showed 95% effectiveness on S?1 and Thuja orientalis showed 96% effectiveness on S?5. In antioxidant activities of the herbal medicines, extract from Thuja orientalis showed the highest level of 81.08% DPPH radical scavenging activity and Illicium verum extract also showed high antioxidative activity of 80.45%. Thuja orientalis had a large amount of phenolic compound with 115.24 ㎍/mL among the herbal medicines.
규제액면기법의 전사방식 광조형 시스템을 위한 이형력 감소
김혜정(Hye Jung Kim),하영명(Young Myoung Ha),박인백(In Baek Park),김민섭(Min Sub Kim),조광호(Kwang Ho Jo),이석희(Seok Hee Lee) Korean Society for Precision Engineering 2013 한국정밀공학회지 Vol.30 No.9
Projection-based stereolithography is divided into constrained-surface and free-surface type according to controlling liquid layer. The constrained-surface type has a uniform layer thickness due to the use of a projection window, which covers the pattern generator such as liquid crystal display. However, the adhered resin on the projection window causes trouble and requires great separation force when the cured layer is separated from the window. To minimize the separation force, we developed a system to measure the separation force. The influence of material covering the pattern generator and the resin temperature is investigated in the system. Several structures according to the resin temperature and the velocity of z-axis elevation are compared. As a result, the fabrication condition to minimize the separation force reduces the process time.
LCD 와 가시광선 LED 기반의 광조형 시스템을 위한 수지의 경화특성
김가영(Ga Young Kim),하영명(Young Myoung Ha),박인백(In Baek Park),김민섭(Min Sub Kim),조광호(Kwang Ho Jo),이석희(Seok Hee Lee) Korean Society for Precision Engineering 2013 한국정밀공학회지 Vol.30 No.8
Stereolithography can be classified into two main categories according to the cross-sectional shape: scanning type and projection type. Projection stereolithography has significant advantages when making a layer using a single patterned beam, and results in improved speed and accuracy. To implement relatively low-cost projection stereolithography, we developed a system using a commercially available resin, which cures on exposure to visible light. The optimum photoinitiator was investigated, as well as the mixing ratio. The viscosity, shrinkage, curing depth and tensile strength were evaluated through several experiments on fabricated three-dimensional structures, and thus an optimal resin selection system was developed.