• 한국정밀공학회지
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• 제21권6호
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• pp.153-159
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• 2004

In this study, a new process to pattern directly on a thin metal layer using improved nano replication printing (nRP) process is suggested to evaluate the possibilities of fabricating a stamp for nano-imprinting. In the nRP process, any figure can be replicated from a bitmap figure file in the range of several micrometers with nano-scaled details. In the process, liquid-state resins are polymerized by two-photon absorption which is induced by femto-second laser. A thin gold layer was sputtered on a glass plate and then, designed patterns or figures were developed on the gold layer by newly developed top-down building approach. Generally, stamps fur nano-imprinting have been fabricated by using the costly electron-beam lithography process combined with a reactive ion-etching process. Through this study, the effectiveness of the improved nRP process is evaluated to make a stamp with the resolution of around 200nm with reduced cost.

• 한국정보과학회논문지:정보통신
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• 제28권4호
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• pp.611-620
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• 2001

최선의 전송(Best Effort) 서비스를 제공하는 현재의 IP 멀티캐스트 서비스의 특성상 신뢰전송을 요구하는 각종 응용들의 요구를 만족시키기 위해서는 추가적인 신뢰전송 프로토콜이 필요하다. 이러한 요구에 따라 신뢰적인 멀티캐스트 전송 프로토콜에 대한 연구가 수행되고 있는 가운데, 계층적 트리를 구축하여 신뢰성을 보장하는 노력이 활발하게 진행되고 있다. 계층적 트리 기반의 방식은 높은 확장성을 보장하면서 효율적으로 신뢰성을 보장하지만 전송단계에서 효율적인 논리 트리 구축 방안이 제공되어야 한다. 논리적인 제어 트리 구축은 수신자 기반의 상향식 (bottom-up) 방식이 주로 사용되어 왔으나 이 방법은 병렬적 트리 구성을 통하여 신속한 트리 구축을 할 수 있다는 장점이 있지만 제어 트리 상에 루프 (loop)가 발생할 수 있다는 단점과 메시지 부하가 커지는 단점이 있다. 이에 본 논문은 하향식(top-down) 기반의 제어 트리 구축 방안을 제안한다. 하향식 방식은 단계적인 트리 구축을 통하여 루프 발생을 방지 할 수 있다. 또한 성능평가를 통하여 메시지 부하를 줄일 수 있다는 것을 보였다. 본 논문은 응용의 요구 사항에 맞추어 상향식과 하향식을 선택적으로 사용할 것을 제안한다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 추계 학술발표회
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• pp.1666-1672
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• 2008

In this study, it collected and analyzed a construction case of the improved top-down support system application field on a case by case retaining wall method. The behavior of horizontal displacement was analyzed according to retaining wall type after reviewing a design stage and estimated horizontal displacement under the construction. The study results showed that it is judged stable until excavation termination irrelevant to a retaining wall method at the improved top-down support system application. It is judged that the settlement of behind ground can minimize because the retaining wall head displacement also behave stably. It was compared the predicted horizontal displacement in design and the measured horizontal displacement acquired through a measurement by using Elasto-Plastic analysis program. The comparison results showed that a similar horizontal displacement was predicted within stability standard irrelevant to a retaining wall method. So, it is decided that the advanced prediction is reasonable by Elasto-Plastic analysis in design applied the improved top-down support system. In the case of the ground anchor method application under a same condition, it is decided that a horizontal displacement will more increase than the improved top-down support system is applied. If a section condition is same, it was decided that to apply top-down support system is more stable than that.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2007년도 춘계학술논문 발표대회
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• pp.29-31
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• 2007

Building construction in downtown is ever increasing with a strong demand. Top-Down Method is one of suitable construction method for its advantage in minimizing disturbance to neighborhood. Along with these reasons construction site has developed lots of new methods and materials for Time-Cost Trade-off and improving constructability. Opened Slab is one of these method which resist the horizontal force by slab and it has many merit about construction time and unity. We analyze the compression tests on opened slab for the application.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2023년도 봄 학술논문 발표대회
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• pp.339-340
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• 2023

Steel construction is one of the commonly used methods in building construction due to its efficiency in terms of time and cost. In particular, the top-down method using steel frames is widely used in the construction of underground structures in urban areas to shorten the construction period. However, there is currently no standardized cost estimation for subway steel frame construction in Korea, causing difficulties in determining the expected cost. In this study, we aim to provide basic data for establishing a cost estimation standard for subway steel frame construction through on-site surveys of subway steel frame construction commonly used in urban areas.

• 한국공간구조학회논문집
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• 제11권2호
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• pp.129-138
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• 2011

지하공사는 상부층의 구조물과 연계된 시공순서에 따라 Bottom-Up공법, Up-Up공법 그리고 Top-Down 공법으로 대별할 수 있다. 탑다운 공법을 사용하면 건물의 본구조를 흙막이지보공으로 이용하면서 상층에서 하층으로 굴착과 구체구축을 반복하여 시공함으로써 인접구조물이나 주변 지반의 변위를 극소화 시킬 수 있다. 이는 토류벽의 안정성이 높으며, 각층의 바닥슬래브를 작업공간으로 사용하여 도심지 공사에서 작업장 확보가 용이하다. 그러나 굴토작업이 슬래브 하부에서 진행되므로 작업 능률 및 작업환경이 저하되고, 어스앵커 공법보다 경제성이 없다는 이유로 다소 회피하는 경우가 종종있다. 따라서 본 논문에서는 터파기 공사는 세미오픈컷 공법을 적용하고 흙막이 공법에는 지하연속벽(슬러리월)을 그리고 지보공으로는 C.W.S공법을 적용한 역타공법으로 대상현장을 중심으로 기존 역타공법과 경제성, 공사기간 및 작업성 등을 분석 제시하였다. 토사운반 및 철골설치공사 작업의 용이성과 PRD 공사의 정밀도 향상 등의 품질관리가 우수하며, 공기단축이 가능하였다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2019년도 춘계 학술논문 발표대회
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• pp.190-191
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• 2019

In complex waterproofing method, the stability of the joint is an important factor. The joints should not be broken for repeated movements and tensile forces. Therefore, we tried to confirm the stability of joints in newly developed joints and general joints. Repeated fatigue resistance performance tests and joint tensile strength tests were carried out on four types of joints. The fatigue resistance performance test showed no abnormality in all four types. It was confirmed that the newly developed top-down joint has higher stiffness than existing joints.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2006년도 추계 학술논문 발표대회 논문집
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• pp.25-28
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• 2006

The contiguous construction in downtown area requires an appropriate substructure construction method since it results in the insufficient working spaces and frequent public resentment by noise and vibration. In particular, Top-down method usually is applied for downtown construction, and followed by several difficulties in casting the slab concrete for substructure. In this study, we focus on the improvement workability for substructure construction.

• 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.

• 한국안전학회지
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• 제10권3호
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• pp.96-105
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• 1995

The better industry develops, the more spaces need but in the limited area. Most building become larger and more complicated if the more spaces need in the constant area. And this leads to do underground work in long period generally six(6) months for 6 basement stories due to the selection of TOP DOWN technique. Working environment in this underground area can be problems and should not be overlooked, because air quality in underground spaces become quickly worse. Recently, department name to control construction safety has been changed to ENVIRONMENT & SAFETY TEAM from SAFETY TEAM. This means that it is very important to control against environmental condition at site so much. Overall construction work as well as underground work should conform to the requirement of working environment, particularly against inhabitants around the construction area. Strut protection, one of earth protection method, in case to 40m long strut may become weaker due to thermal stress or its longitudinally compressive strain and the another one, earth anchor protection may not be applied to the site In case of encroaching on vertical underground borderline because of regulation to prohibit it. It is necessary that TOP DOWN technique should be introduced in order to solve the external and internal problem of the site such as difficulty level of the work, potential danger with excavating depth, and shortening workperiod. It is needed that improving way of working condition should be shown and simplified computer simulation program should be also provided for checking pollution level & ventilation, excluding of lighting problem here. Results measured with conformance to the Regulation for Working Environment Measurement, enforced by Ministry of Labor have been applied to the computer program developed here. Sample air taken at unit workplace which was considered as exposing condition of pollutant at breathing point and within a range of behavior of the workers, Identified exposing group in underground work, using Moded Flow Life Finally, three types of ventilation system, type I with blower & ventilator, type II natural supply with mechanical ventilation system, and type I mechanical ventilation with Drivent Fan Unit System are selected for this study.