• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2003.05a
• /
• pp.13.2-17
• /
• 2003

When fresh concrete is exposed to low temperature, the concrete may suffer frost damage due to freezing at early ages and strength development may be delayed. One of the solution methods to resolve these problems is to lower freezing temperature of concrete by the use of chemical admixture called Accelerators for Freeze Protection. In this study, it was the results of appling cold weather concrete using Accelerator for Freeze Protection in the Daewoo Trump world field. Before the application of the cold weather concrete using accelerator for freeze protection, we executed the some test in the laboratory and mock-up test in the field. We examined the manifestation of compressive strength complying with the amount of Accelerators for Freeze Protection and curing conditions, and then made a selection of most suitable amount of Accelerators for Freeze Protection.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2016.05a
• /
• pp.170-171
• /
• 2016

The unity of korean peninsula have traditionally been established as major policy in korea government. Present government also set Trust Process on the Korean Peninsula as national high-level strategies for unity, and construction field related directly to living of north korean as major industry which would be implemented in early stage. Deterioration level of architectural facilities in north korea is known as very high, so a huge budget would be required to improve aging architectural facilities for stability of social and living of north korean. Therefore the purpose of this study deduct financing plan for improving aging architectural facilities in north korea and selection of optimal alternative securing effectiveness. The results of this study could be utilized as preliminary data for establishment of master plan and policy for improving deteriorated facilities in situation of united korean peninsula.

• Journal of the Korean Society for Marine Environment & Energy
• /
• v.2 no.2
• /
• pp.95-102
• /
• 1999

Various types of oil response equipments and oil recovery vessels are being developed in Korea from the 1990s to respond nil spill accidents. It should be considered prior to the selection of the oil skimmers to make the oil recovery system more efficient at early stage of oil spill accidents. Rotating baldes of vortex skimmer beneath the water surface concentrate oil and draw it into the weir, where it flows to a collection sump. In this study a recently developed Vortex-Disc skimmer(model : VDS-50) is introduced and the performance test results for the skimmer are discussed.

• English Language & Literature Teaching
• /
• v.8 no.2
• /
• pp.219-243
• /
• 2003

The purpose of the present study was to develop a new English language model of an integrated syllabus for kindergarteners, in order to teach and learn English. An English syllabus is a tool for realizing the goals of a curriculum, in the planning of language teaching that is primarily concerned with content and method components. Thus appropriate syllabus design can play an important role on the whole effectiveness of early English education, because it presents selection and grading of content and method for English textbooks. The basic principle of the present syllabus is based on the national curriculum of kindergartens. Developing an English syllabus model for kindergarteners could suggest standards and directions for teaching and writing adequate English textbooks for kindergarteners. The syllabus model integrates competence in communication using a proportional approach and focussing on the characteristics of kindergarteners. This study presented an integrated English syllabus for kindergarteners at the ages of five, six, and seven.

• Proceedings of the KSR Conference
• /
• 2005.11a
• /
• pp.258-263
• /
• 2005

The purpose of this research is to present a practical method for efficiently monitoring a reliability growth process using AMSAA(Army Materiel Systems Analysis Activity) reliability growth model. The presented method is viable for identifying failure modes, incorporating design changes and monitoring reliability progress on an on-going basis during the early stages of a product development program. According to the Application Guide for EN 50126(RAM part for Rolling Stock), reliability growth monitoring is essential part of the main tasks of design phase in RAM growth monitoring. Implementation of reliability growth management program will provide very useful information on concept selection, product/process reliability, and cost effectiveness without too much time, money and engineering effort being spent on the development of failure suspect parts.

• Journal of Communications and Networks
• /
• v.9 no.2
• /
• pp.141-149
• /
• 2007

Multiple-input multiple-output (MIMO) transmit pre-coding/beamforming can significantly improve system spectral efficiency. However, several obstacles prevent precoding from wide deployment in early wireless networks: The significant feedback overhead, performance degradation due to feedback delay, and the large storage requirement at the mobile devices. In this paper, we propose a precoding method that addresses these issues. In this approach, only 3 or 6 bits feedback is needed to select a precoding matrix from a codebook. There are fifteen codebooks, each corresponding to a unique combination of antenna configuration (up to 4 antennas) and codebook size. Small codebooks are prestored and large codebooks are efficiently computed from the prestored codebook, modified Hochwald method and Householder reflection. Finally, the feedback delay is compensated by channel prediction. The scheme is validated by simulations and we have observed significant gains comparing to space-time coding and antenna selection. This solution was adopted as a part of the IEEE 802.16e specification in 2005.

• IE interfaces
• /
• v.6 no.2
• /
• pp.19-35
• /
• 1993

This paper presents the development of a knowledge-based expert system to assist for designer in the process of designing products for easier assembly. The developed expert system for supporting assembly-oriented product design, which is named as DFA-MASTER, consists of two subsystems such as "Assembly Method Selection System" which provides feasible assembly methods to designer and "DFA-Analysis System" which provides guidelines to improve assemblability of products in the early stage of product design. The developed system is interfaced with AutoCAD system and can be run under PC environments. By using DFA-MASTER, designer can obtain feasible assembly methods which have high assemblability under the given asssembly conditions and also evaluate the assemblability of part feature or product structure.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.57 no.8
• /
• pp.1334-1341
• /
• 2008

This paper introduces an approach of Hybrid Particle Swarm Optimization(HPSO) for a security-constrained economic dispatch(SCED) with line flow constraints. To reduce a early convergence effect of PSO algorithm, we proposed HPSO algorithm considering a mutation characteristic of Genetic Algorithm(GA). In power system, for considering N-1 line contingency, we have chosen critical line contingency through a process of Screening and Selection based on PI(performance Index). To prove the ability of the proposed HPSO in solving nonlinear optimization problems, SCED problems with nonconvex solution spaces are considered and solved with three different approach(Conventional GA, PSO, HPSO). We have applied to IEEE 118 bus system for verifying a usefulness of the proposed algorithm.

• Biomaterials and Biomechanics in Bioengineering
• /
• v.2 no.2
• /
• pp.61-69
• /
• 2015

Undifferentiated stem cells are being studied to obtain information on the therapeutic potential of isolates that are produced. Dental Pulp Stem Ccell (DPSC) may provide an abundant supply of highly proliferative, multipotent Mesenchymal Stem Cells (MSC), which are now known to be capable of regenerating a variety of human tissues including bone and other dental structures. Many factors influence DPSC quality and quantity, including the specific methods used to isolate, collect, concentrate, and store these isolates once they are removed. Ancillary factors, such as the choice of media, the selection of early versus late passage cells, and cryopreservation techniques may also influence the differentiation potential and proliferative capacity of DPSC isolates. This literature review concludes that due to the delicate nature of DPSC, more research is needed for dental researchers and clinicians to more fully explore the feasibility and potential for isolating and culturing DPSCs extracted from adult human teeth in order to provide more accurate and informed advice for this newly developing field of regenerative medicine.

• Journal of Aerospace System Engineering
• /
• v.4 no.3
• /
• pp.34-38
• /
• 2010

ACN(Aircraft Classification Number) is allocated by marketing group during early stage of aircraft design phase and is a critical parameter to decide whether the designed aircraft can be landed or not in a certain airport. The loading on the main landing gear wheels, selection of main landing gear tire and estimation of ACNs for flexible and rigid pavements were done for the proposed medium-class aircraft. The estimated ACN values are compared with the similar class aircraft. And PCN(Pavement Classification Number) values of airport in Korea are surmmarized. Results showed that the currently proposed medium-class aircraft can land any airport in Korea.