• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 가을 학술발표회 논문집(I)
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• pp.48-53
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• 1998

The purpose of this study to fine the mixture of concrete for Top-Down method. As a result, In fresh concrete, slump value and slump-flow value were increased as fly ash concrete(10% ratio). When plasticizer was added 1.5% by weigh of binder in concrete, no fly ash concrete and fly ash concrete(10% ratio) all occurred segregation. And, no fly ash concrete and fly concrete(10% ratio) all showed compressive strength development close plain concrete as increasing plasticizer quantity. Especially, in case of 1.5% plasticizer of binder showed high compressive strength development.

• 국제학술발표논문집
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• The 3th International Conference on Construction Engineering and Project Management
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• pp.808-813
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• 2009

Top-down method is widely used for urban area construction for its advantages in reducing environmental problems such as dust and noise, and saving construction cost depending on given conditions of a construction site. Because the excavation and construction of super- and sub-structures of the building have to be proceeded simultaneously, a column has to be embedded prior to excavation. This column is called a pillar column or pre-founded column. Usually a wide flange section is used for these columns. To place the columns, usually the diameter of casing holes needs to be larger than the section of the wide flange itself in order to accommodate a couple of tremie pipes for pouring concrete. In this paper, a newly developed method of using circular pipe as an alternative to the existing wide flange section is discussed. The crucial part of the new method is to develop a connection between the circular column and concrete flat slabs. For shear force transfer from concrete slab to the concrete filled tube (CFT) column, shear jackets with studs and shear bands are proposed. The studs are welded on the jackets at shop and placed around the circular column on site. The shear bands are welded on the outer side of the CFT at shop and inserted into ground with the CFT. Test results and application of the method to a construction site are also provided in this paper.

• 한국지반환경공학회 논문집
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• 제17권11호
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• pp.45-53
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• 2016

패널식 옹벽은 지보재를 통한 선지보 개념으로 프리캐스트 패널과 체결하여 원지반 강도를 최대한 보호하며 보강하는 공법이다. 최근 건설공사에서 대규모 깎기비탈면의 형성에 따른 토공량 증가와 환경 훼손을 최소화하고 용지제한에 따른 토지의 효율적인 이용을 위해 패널식 옹벽의 적용이 증가하고 있는 추세이다. 원지반 부착식 패널옹벽은 자연암반 질감을 갖는 프리캐스트 콘크리트 패널을 사용하여 경관성을 향상시키고 완전한 Top-Down 시공법을 구현하도록 개발된 공법으로 수직절취와 패널의 원지반 직접부착이 가능해 비탈면 이완을 최소화하고 터파기 및 되메우기 공종을 배제하여 시공성을 개선하였다. 본 연구는 현장시험시공을 수행하여 수직절취 및 Top-Down에 대한 시공성을 확인하고, 대형재하시험과 하중단계별 계측결과를 분석하여 원지반 부착식 패널옹벽의 거동특성을 분석하였다.

• International Journal of Contents
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• 제7권4호
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• pp.64-69
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• 2011

Recently, as smart devices are distributed more and more, the need for education of developing contents based on smart media increases. In order to develop contents based on smart media, it is necessary to learn new programming language as well as to understand the structure of platforms as device-manufacturers and communication companies have different platforms. Generally, the problem in education of programming is that it can provide learning to understand the language stage by stage, but it is difficult to suggest a clear result such as completion of learner's project from macroscopic and integrated approach. Especially, there is a difficult of learning several programming languages due to the characteristics of platforms in developing smart contents. Accordingly, in the education of programming for developing smart contents, it is not appropriate to use the traditional teaching method of programming which conducts projects from an integrated point of view after learning the grammatical elements of the language. This paper aims to suggest the top-down teaching method as an effective teaching method for developing contents based on smart media, and to analyze the effect after developing and applying the suggested teaching model.

• 대한치과보철학회지
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• 제58권4호
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• pp.356-362
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• 2020

강동경희치대병원 보철과에서는 치료계획단계에서 마지막 결과를 미리 형상화하고 그것에 입각하여 치료를 진행하는 Top-Down 개념의 치료접근법을 2006년부터 실행하고 있다. 이번 증례도 그 개념에 입각하여 임플란트 수술에 앞서 미리 최종 보철치료의 방법과 결과를 형상화시켜 놓고 치료를 진행한 실례이다. 임플란트 보철의 여러 방법 중 시멘트 유지방식은 임플란트의 기울기에 구속받지 않고 간단하게 보철물 제작이 가능하나, 접착 후 치은 연하의 잉여 시멘트를 완전하게 제거하기 어렵고, 필요할 때 탈착이 불편하다는 단점이 있다. 따라서 전치부 임플란트 보철수복 시 SB-locking method의 유지방식을 이용하여 시멘트 유지방식의 문제를 해결하면서 심미적인 임플란트 보철수복이 가능했던 증례를 보고하고자 한다.

• 한국분말재료학회지
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• 제13권6호
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• pp.415-420
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• 2006

Nanostructured metallic materials are synthesized by bottom-up processing which starts with powders for assembling bulk materials or top-down processing starting with a bulk solid. A representative bottom-up and top-down paths for bulk nanostructured/ultrafine grained metallic materials are powder consolidation and severe plastic deformation (SPD) methods, respectively. In this study, the bottom-up powder and top-down SPD approaches were combined in order to achieve both full density and grain refinement without grain growth, which were considered as a bottle neck of the bottom-up method using conventional powder metallurgy of compaction and sintering. For the powder consolidation, equal channel angular pressing (ECAP), one of the most promising method in SPD, was used. The ECAP processing associated with stress developments was investigated. ECAP for powder consolidation were numerically analyzed using the finite element method (FEM) in conjunction with pressure and shear stress.

• 대한기계학회논문집
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• 제19권7호
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• pp.1604-1618
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• 1995

In the process of mechanical assembly design, assembly modeling systems have been used mainly for the design verification before manufacturing by enabling to check the interference and/ or the dynamic and kinematic performance. However, the conventional assembly modeling systems have a shortcoming that they can not be used in the initial design stage but can be used only after the design is fully completed. In other words conventional assembly modeling systems provide bottom-up modeling which means that the detailed modeling of components must precede the definition of relationships between them. To resolve this problem, an assembly modeling system is proposed to provide a top-down modeling environment in which components and assembly can be modeled simultaneously. To this end, an assembly data structure suitable for top-down assembly modeling has been established. Feature positioning Module(FPM) using geometric constraints has been also developed. The Sekective Solving Method proposed for FPM is based on the priority between the constraint equations and enables the designer's intent expressed by geometric constraints to be maintained throughout the whole modeling process. Finally, the feature based modeling technique using two-level features has been developed. Two-level features include an abstract model and a detailed model in a merged form in non-manifold data frame.

• Geomechanics and Engineering
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• 제31권5호
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• pp.489-503
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• 2022

A 1257-m-long irregular deep foundation pit located in the central of Nanjing, China was constructed using the combined full-width and half-width top-down method. Based on the long-term field monitoring data, this study analyzed the evolution characteristics of the vertical movement of the columns, internal force of the struts, and axial force of the structural beam and slab. The relevance of the three mentioned above and their relationship with the excavation process, structural system, and geological conditions were also investigated. The results showed that the column uplift was within the range of 0.08% to 0.22% of the excavation depth, and the embedded depth ratio of the diaphragm wall and the bottom heave affected significantly on the column uplift. The differential settlement between the column and diaphragm wall remained unchanged after the base slab was cast. The final settlement of the diaphragm wall was twice the column uplift. The internal force of the struts did not varied monotonically but was related to numerous factors such as the excavation depth, number of struts, and environmental conditions. Additionally, the dynamic force and deformation of the columns, beams, and slabs were analyzed to investigate the inherent relationship and variation patterns of the responses of different parts of the structure.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1987년도 전기.전자공학 학술대회 논문집(II)
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• pp.1540-1542
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• 1987

This paper describes a special-purpose schematic editor program which is appropriate for Top-Down methodology of hierarchical logic design. The data structure which has capability to be shared with multi-level logic simulator is developed. For the purpose of efficient search, a new indexing method is designed. That is exponentially distributed one dimentional bin based on probability of presence of graphic elements.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2008년도 추계 학술논문 발표대회
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• pp.129-133
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• 2008

For the construction of Top-Down structures, it is crucial to have a solid connection between prefounded columns and slabs. This paper presents a new construction method for the connection when using a circular Concrete Filled Tube (CFT) as a prefounded column as an alternative to currently using wide flange type columns. The development of shear studded jackets along with a shear band suitable for the circular shape of the column has been made. The details and mechanism of the connection is explained together with the results of experiments which verified the structural integrity of the connection.