• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.11a
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• pp.196-197
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• 2021

The underground method can be divided into Top-Down, Semi-Top-Down, Up-Up and Down-Up methods according to the construction order of the upper and lower structures. Among them, the Down-Up method proceeds with the construction of the first floor and its lower floors, and when the foundation is completed, the vertical members of the basement are sequentially completed from the foundation and the above-ground floor is constructed. In this paper, the crack reduction method around the open section of the Down-Up method affected by earth pressure was analyzed and divided into design and construction parts.

• Magazine of the Korea Concrete Institute
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• v.27 no.3
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• pp.48-52
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• 2015

• Proceedings of the Korea Database Society Conference
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• 2010.06a
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• pp.181-185
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• 2010

The current method for accessing interconnection charges in Korea, called a hybrid model in this paper, mixes a top-down with a bottom-up LRIC model. The method has given stable charges so far. However, according to the fundamental changes of the market, policy, and network technology in the telecommunications industry, it requires analyzing the validity of the method. We investigate the problems of the top-clown, bottom-up, and hybrid model used in Korea and analyze their effect on regulation policy.

• Journal of the Korean Geosynthetics Society
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• v.11 no.1
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• pp.11-21
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• 2012

The Rankine(1857)'s earth pressure and the Hong and Yun(1995a)'s earth pressure was applied to analyze the lateral displacement of diaphragm wall applied to the Top-Down construction method using the computer program, which is a common design program for diaphragm wall. The lateral displacement estimated by the computer program was compared with the lateral displacement measured by inclinometer. The Rankine's earth pressure has been widely used to design the diaphragm wall in the analysis of computer program. As the result of comparison, the lateral displacement of diaphragm wall was predicted differently according to the applied earth pressures. The behavior of lateral displacement predicted by the Rankine's earth pressure was different with displacement measured by inclinometer and the lateral displacement at the bottom part was overestimated. However, the lateral displacement predicted by the Hong and Yun's earth pressure is similar to the behavior and maximum value of real displacement. Therefore, the Hong and Yun's earth pressure is more suitable than the Rankine' earth pressure to design the diaphragm walls applied to the Top-Down Construction Method.

• Journal of the Korean Geotechnical Society
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• v.22 no.4
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• pp.11-19
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• 2006

For the last decade, the hi-directional testing method has been advantageous over the conventional pile load testing method in many aspects. However, because the hi-directional test uses a loading mechanism entirely different from that of the conventional pile load testing method, many investigators and practicing engineers have been concerned that the hi-directional test would give inaccurate results, especially about the pile head settlement behavior. Therefore, a hi-directional load test and the conventional top-down load test were executed on 1.5 m diameter cast-in-situ concrete piles at the same time and site. Strain gauges were placed on the piles. The two tests gave similar load transfer curves at various depth of piles. However, the top-down equivalent curve constructed from the hi-directional load test results predicted the pile head settlement under the pile design load to be about one half of that predicted by the conventional top-down load test. To improve the prediction accuracy of the top-down equivalent curve, a simple method that accounts for the pile compression is proposed. It was also shown that the strain gauge measurement data from the hi-directional load test could reproduce almost the same top-down curve.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.7
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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.

• Journal of Information Technology Services
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• v.9 no.3
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• pp.95-106
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• 2010

Many researches have been performed to increase energy-efficiency in wireless sensor networks. One of primary research topics is about clustering protocols, which are adopted to configure sensor networks in the form of hierarchical structures by grouping sensor nodes into a cluster. However, legacy clustering protocols do not propose detailed methods from the perspective of implementation to determine a cluster's boundary and configure a cluster, and to communicate among clusters. Moreover, many of them involve assumptions inappropriate to apply those to a sensor field. In this paper, we have designed and implemented a new T-Clustering (Top-down Clustering) protocol, which takes into considerations a node's density, a distance between cluster heads, and remained energy of a node all together. Our proposal is a sink-node oriented top-down clustering protocol, and can form uniform clusters throughout the network. Further, it provides re-clustering functions according to the state of a network. In order to verify our protocol's feasibility, we have implemented and experimented T-Clustering protocol on Crossbow's MICAz nodes which are executed on TinyOS 2.0.2.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.1
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• pp.128-133
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• 2013

Si Nanowire (Si-NW) arrays were fabricated by top-down method. A relatively simple method is suggested to fabricate suspended silicon nanowire arrays. This method allows for the production of suspended silicon nanowire arrays using anisotropic wet etching and conventional MEMS method of SOI (Silicon-On-Insulator) wafer. The dimensions of the fabricated nanowire arrays with the proposed method were evaluated and their effects on the Field Effect Transistor (FET) characteristics were discussed. Current-voltage (I-V) characteristics of the device with nanowire arrays were measured using a probe station and a semiconductor analyzer. The electrical properties of the device were characterized through leakage current, dielectric property, and threshold voltage. The results implied that the electrical characteristics of the fabricated device show the potential of being ion-selective field effect transistors (ISFETs) sensors.

• Journal of the Korean GEO-environmental Society
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• v.17 no.11
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• pp.45-53
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• 2016

A precast panel wall system resists against the horizontal earth pressure by increasing the shear strength of ground by reinforcement connected to the panel. The application of precast panel wall system is growing to lately minimize the earth work and environmental damage caused by large cut slope and to use the limited land effectively. The ground adhered panel wall system is the construction method that has the panel engraved with natural rock shape to improve the landscape. This system is developed to complete Top-Down method, and it is possible to have vertical cut, and to adhere to in-situ ground, improve construction ability by minimizing the ground relaxation and exclusion the trench and backfill process. In this study the field tests were performed to verify the construction ability about the vertical cut and complete Top-Down process and the construction behavior of ground adhered panel wall system was analyzed by large scale loading test and measurement results during loading test.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.7
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• pp.9-16
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• 2017

To improve concrete-filled tube (CFT) columns, an octagonal concrete-filled tube (OCFT) column was developed. Because the OCFT column requires a small boring diameter, the OCFT column is suitable for Top-Down construction method. In this study, the compression performance of OCFT column to be used as Top-Down pile foundation was verified using centrifuge equipment. Under 12 g centrifugal acceleration, the bearing capacities of the pile foundations of OCFT and H-shaped sections were tested. When the pile foundations were embedded in soil of full depth, 45 % of the design strength, which was assumed to be the construction load, was supported by the OCFT and H-shaped sections in the elastic states. When the pile foundations were embedded in soil of half depth, the buckling of the pile foundations was not investigated. After the loading test, the rock at the bottom of pile foundation, which had a strength of 3.5 MPa, was not damaged due to 45 % of the design strength.