포스터14 : Sn-Ag 계 무연 solder 의 Creep 특성에 관한연구

백대화,서윤종,이도재 대한금속재료학회 ( 구 대한금속학회 ) 1999 대한금속학회 추계학술대회 개요집 Vol.1999 No.-

Sn-3.5wt.%Ag-1wt.%Zn땜납과 Cu 기판간의 미세조직 및 계면반응

백대화,서윤종,이경구,이도재 한국주조공학회 2003 한국주조공학회지 Vol.23 No.2

지하공간의 리모델링 전·후 공간구조 분석과 길 찾기에 관한 연구 - 복합 상업시설 코엑스 몰의 랜드마크를 중심으로 -

백대화,임리사 대한건축학회 2024 대한건축학회논문집 Vol.40 No.1

2013년 리모델링 이후에도 COEX Mall의 방문객 수가 예상과 달리 감소하는 현상을 중심으로, 본 연구는 리모델링 전후의 공간 구조를 비교하고, 방문객의 공간 인식에 영향을 미치는 요소를 파악하였다. 방문객들이 코엑스 몰 내에서 위치 파악 및 이동에 대한 어려움을 경험하는 문제에 주목하여, 공간 구문 이론을 활용한 축선도 분석을 실시하였다. 본 분석은 통합도, 공간구조명료도, 강밀도 등 공간 구조의 핵심 지표를 중심으로 진행되었다. 리모델링 이후 COEX Mall의 공간 구조 상의 다양한 측면, 특히 평균 통합도, 10% 통합도 코어, 공간구조명료도, 강밀도 등이 약간 개선되었음을 확인하였다. 그러나 10% 통합도 코어와 랜드마크 사이의 관계를 깊게 탐색한 결과, 리모델링 이후의 랜드마크가 10% 통합도 코어에 연결되지 않아 다른 위치에서 접근하기 어려움을 확인하였다. 이는 랜드마크가 그 역할을 효과적으로 수행하지 못했음을 시사한다. 이 연구 결과는 다목적 상업 공간을 리모델링하는 과정에서 랜드마크의 배치와 분포를 신중히 고려해야 함을 강조하며, 이는 방문객의 공간 인식과 길찾기에 결정적인 영향을 미칠 수 있음을 보여준다. The number of visitors to the COEX Mall decreased after the 2013 remodeling, contrary to the prediction that the number would increase. Following the remodeling, visitors experienced inconvenience in using the mall and had difficulties determining their locations andsurroundings. They faced challenges with spatial cognition and way-finding. This study aimed to compare the spatial structure of the mallbefore and after remodeling and identify factors influencing visitors' spatial cognition. In the methodology section, space syntax theory wasemployed to analyze axial map. The analysis focused on several key indices, including integration, intelligibility, and intensity. Thiscomprehensive approach provided valuable insights into the spatial structure and its effects on navigation within the studied area. Throughaxial map analysis, various aspects of the COEX Mall, including total average integration, 10% integration core, intelligibility, and intensity,showed slight improvements after the remodeling. However, further examination of the relationship between the 10% integration core axis andthe landmark revealed that the landmarks after the remodeling are not attached to the integration core making it hard to access from otherlocations, suggesting that the landmark was less effective in its role. This finding underscores the importance of carefully considering theplacement and distribution of landmark when planning the remodeling of multi-purposed commercial spaces, as they can have a substantialimpact on the overall spatial characteristics and navigability for visitors.

Sn-3.5wt.%Ag- 1wt.%Zn 땜납과 Cu 기판간의 미세조직 및 계면반응

백대화(Dae Hwa Baek),서윤종(Youn Jong Seo),이경구(Kyung Ku Lee),이도재(Doh Jae Lee) 한국주조공학회 2002 한국주조공학회지 Vol.22 No.2

N/A This study examined the effects of adding Zn to Sn-3.5Ag solder on the microstructure changes and behavior of interface reaction of the solder joint with Cu substrate. The solder/Cu joints were examined with microscope to observe the characteristics of microstructure changes and interfacial reaction layer with aging treatment for up to 120 days at 150℃. Results of the microstructure changes showed that the microstructures were coarsened with aging treatment, while adding 1%Zn suppresses coarsening microstructures. The Sn-3.5Ag/Cu had a fast growth rate of the reaction layer in comparison with the Sn-3.5Ag-1Zn at the aging temperature of 150℃. Through the SEM/EDS analysis of solder joint, it was proved that intermetallic layer was Cu_6Sn_5 phase and aged specimens showed that intermetallic layer grew in proportion to t^1/2, and the precipitate of Ag_6Sn occur to both inner layer and interface of layer and solder. In case of Zn-containing composite solder, Cu_6Sn_5 phase formed at the side of substrate and Cu-Zn-Sn phase formed at the other side in double layer. It seems that Cu-Zn-Sn phase formed at solder side did a roll of banrier to suppress the growth of the Cu_6Sn_5 layer during the aging treatment.

중소기업 경쟁력 향상을 위한 기술수명주기별 R&D 지원 방안 연구

백대화 ( Dae Hwa Back ),김은희 ( Eun Hee Kim ),김은미 ( Eun Mi Kim ) 한국중소기업학회 2013 中小企業硏究 Vol.35 No.3

중소기업에 대한 R&D의 중요성이 강조됨에 따라 정부 R&D자금의 확대뿐만 아니라, R&D 지원 프로젝트의 효과적인 관리를 통한 지원의 성과 향상을 고려해야 할 필요가 있다. 본 연구는 R&D 지원 성과분석을 위한 중소기업청의 설문 결과 자료를 활용하여, 정부 지원을 받은 중소기업이 정부 R&D 지원 과제 수행 전·후 기술수준 및 기술자립도에 차이가 있는지, 기술적·경제적 성과, 기여도 등이 기술수명주기별로 지원성과의 차이가 있는지 분석하고, 기술수명주기별로 차별화된 정책 제안을 목적으로 한다. 분석 결과 개발제품 매출액, 기술수준변화, 기술자립도, 기여도에서 기술수명주기별로 유의한 차이가 나타났고, 이러한 분석결과를 바탕으로 정부 지원 과제 선정 시 기술수명주기별로 선정 기준을 달리하여 지원하는 개선된 방향을 제시함으로써 중소기업 정책의 효율성 제고에 기여할 수 있을 것이다. According to the increasing importance of the SMEs` R&D, it is necessary to consider not only the government funding scale but also the effective operation of the R&D support system. The purpose of this research is to analyze the differences in technological levels and technological independence degrees between before and after the SMEs` R&D project execution financially supported by the government, based on technology life cycle, and to suggest the improvement ways of the government R&D support system. The results of this study show that there are significant differences in sales, technological level, degree of technological independence, and contribution of new product, according to the phases of technology life cycle. In addition, this research proposes the specified directions of the government R&D supports for SMEs, based on technology life cycle, and it could contribute the improvement of effectiveness in the R&D support policy for SMEs.

건강 중심의 도시 계획을 위한 잠재적 지하공간 거주자들의 관점에서 본 인식에 관한 종합적 분석

백대화(Baek, Dae-Hwa),백정엽(Baek, Jeong-yeop),노재창(Noh, Jae-Chang),임리사(Lim, Lisa) 대한건축학회 2023 대한건축학회 학술발표대회 논문집 Vol.43 No.2

Utilizing underground spaces presents a promising solution to the urban challenges faced by many countries. These challenges include congestion and the need for disaster preparedness. Underground spaces inherently offer protection from environmental extremes and serve as potential safe havens from threats, such as natural disaster. However, public perception of underground living remains a significant obstacle. A recent survey highlighted this issue, showing that many people hold negative views about the prospect of residing in underground spaces. To address these concerns, design recommendations for underground facilities have been proposed. To ensure the successful integration of these spaces into urban planning, it is imperative that future research focuses on refining these guidelines, with a particular emphasis on enhancing public perception of underground living.

Cu 에 대한 Sn-3.5Ag 계 땜납의 젖음성 및 계면반응

백대화(Dae Hwa Baek),이경구(Kyung Ku Lee),박효병(Hyo Byeong Park),정명준(Myung Jun Geong),이도재(Doh Jae Lee) 한국주조공학회 1999 한국주조공학회지 Vol.19 No.3

The wettability and interfacial reaction between Sn-3.5Ag solders and Cu-substrate were examined as a function of alloying element (1Pb, 1Sb) and soldering time. Cu/solder joints were subjected to aging treatments for up to 60 days at 150˚C to observe interfacial compounds and changes of microstructure by optical microscopy, SEM and EDS. The addition of 1Pb to the Sn-3.5Ag solder improves the wetting characteristics of the alloy and lowers the melting temperature. The growth rate of the Cu_6Sn_5 layer in the Sn-3.5 Ag solder/Cu was faster than that in the Sn-3.5Ag-1Sb solder/Cu. The activation energy for Cu_6Sn_5 growth was estimated as 31∼35 kJ/mole. (Received January 15, 1999)

사례기반 건축물 리모델링 지원용 데이터베이스 시스템

백대화(Dae Hwa Baek),백정엽(Jeong Yeop Baek),장성주(Sung Ju Chang) 대한설비공학회 2022 대한설비공학회 학술발표대회논문집 Vol.2022 No.6

This research aims to develop personalized solutions that could cut construction costs by up to 30 percent and heating and cooling loads in existing buildings by up to 50 percent by making low-carbon, energy-efficient renovations. To reach this goal, research and development of the foundation for the optimal model for low-carbon energy efficiency in existing buildings with detailed technology, development of low-carbon energy efficiency technology packages for existing buildings, customization of low-carbon energy efficiency technology, and distribution of the optimal model for low-carbon energy efficiency based on demand are all required as making a database system that collects and sorts cases of remodeling in Korea and other countries. This will help them figure out the best way to make existing buildings use less energy and produce less carbon. Based on this, guidelines are made for future building remodeling to make the best remodeling plan. This study collected domestic and foreign remodeling design/construction cases, made a remodeling case database, made a web-based interface for the remodeling case database, and tested the applicability of remodeling targets on a test-bed.

가변형 차양장치의 적용실태에 관한 탐색 - 해외 건축물의 사례분석을 중심으로 -

백대화(Baek, Dae-Hwa),장성주(Chang, Seong-Ju) 대한건축학회 2021 대한건축학회 학술발표대회 논문집 Vol.41 No.1

This study is to analyze three overseas cases representing notable technological combinations and practical designs of kinetic solar shading devices which are aesthetically compelling but show insufficient performance in terms of building energy reduction and occupants’ visual comfort. Each selected shading device is virtually combined with a campus building located in Daejeon to simulated and analyze its strengths and weaknesses. As a consequence, this exploration on kinetic shading devices could provide a useful insight for optimizing the design of solar shading device targeting effective sunshade and solar control in the future.

In , Bi 가 첨가된 Sn-9wt.%Zn/Cu 접합부의 납땜성 및 기계적 성질

이도재,이경구,백대화 한국주조공학회 2000 한국주조공학회지 Vol.20 No.2

Interfacial reaction and mechanical properties between Sn-Zn-X ternary alloys(X : 3wt.%In, 4wt.%Bi) and Cu-substrate were studied. Cu/solder joints were subjected to aging treatments for up to 50days to see interfacial reaction at 100℃ and then were examined changes of microstructure and interfacial compound by optical microscopy, SEM and EDS. Cu/solder joints were aged to 30days and then loaded to failure at cross head speed of 0.3㎜ min^(-1) to measure tensile strength. According to the results of the solderability test, additions of In and Bi in the Sn-9wt.%Zn solder improve the wetting characteristics of the alloy and lower the melting temperature. Through the EDS and XRD analysis of Cu/Sn-9wt.%Zn solder joint, it was concluded that the intermetallic compound was the γ-Cu_5Zn_8 phase. Cu-Zn intermetallics at Cu/solder interfaces played an important role in both the microstructure evolution and failure of solder joints. Cu/solder joint strength was decreased by aging treatment, and those phenomenon was closely related to the thickening of intermetallic layer at Cu/solder joints.