• Proceedings of the KIEE Conference
• /
• 2009.04a
• /
• pp.84-85
• /
• 2009

전력기술의 발전함에 따라 절연소재 또한 급속한 발전을 가져왔다. 특히, 오랫동안 사용해온 자기재 절연물에서 시공의 용이성, 경량성, 내오염성 등과 같은 장점을 가진 폴리머 절연물로 대체 되어 사용되어져 왔다. 폴리머 애자는 1980년대 말에 최초로 사용되기 시작 하여 2007년 한 해 동안 약 100만여개의 폴리머 애자가 배전선로에 사용되고 있다. 이러한 폴리머 절연재료는 그 수명이 20년 으로 보고되어지는바, 그 수명이 종기인 현재 폐기되는 폴리머양은 점차적으로 증가할 것으로 보여진다. 본 논문에서는 이러한 폴리머 폐기물의 처리를 위한 열분해 특성에 관한 것으로 향후에 효율적인 폴리머 절연폐기물의 처리를 위한 기초 자료로 활용하고자 한다.

• Proceedings of the Korean Institute of Industrial Safety Conference
• /
• 1998.11a
• /
• pp.159-164
• /
• 1998

포틀랜트 시멘트가 개발되어 콘크리트에 응용됨으로서 콘크리트의 적용범위가 무한히 확대되고 있는 상황에서, 최근, 구조물이 고층화, 대형화, 특수화됨에 따라 건설재료인 콘크리트의 고품질화가 요구되고 있다. 이러한 고품질화의 최우선과제로 콘크리트의 고강도화에 관한 많은 연구가 국내외에서 이루어지고 있고, 실제 시공된 사례도 급속히 증가하고 있다. (중략)

• Proceedings of the Korea Information Processing Society Conference
• /
• 2016.04a
• /
• pp.368-371
• /
• 2016

정보 통신 기술의 급속한 발달로 인터넷 환경의 학습은 학습 혁명을 주도하는 핵심적인 위치에 있다. 인터넷 환경은 시공간의 제약 없이 자신이 필요로 하는 다양한 교육과정에 접근이 가능하고 생업과 병행하여 학습을 할 수 있는 접근성을 갖는다. 그러나 인터넷에 대한 접근성의 차이는 디지털 디바이스 현상을 발생하게 하여 온라인 학습자와 오프라인 학습자의 교육격차를 더 크게 한다. 이러한 문제를 해결하기 위해 본 연구는 인터넷 환경이 원활하지 않은 경우에는 지속적인 학습을 진행할 수 있도록 PDF 시스템을 활용한다. 이 시스템을 통해 오프라인에서의 학습 결과를 온라인에 전송하여 이력을 제공하는 시스템을 설계하고자 한다.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
• /
• v.28 no.6
• /
• pp.476-483
• /
• 1999

사회기반시설의 확충을 통한 물류비용 절감을 위해 최근 국내 고속도로 및 국도, 도시교통망의 신.증설이 가속화되고 있는데 특히 1965년 2개 노선 75km로 시작하여 1998년 말 현재 20개 노선 1996.3km인 고속도로는 앞으로 3년 후인 2002년까지 2,800km, 2004년 3,700km의 도로망을 갖추게 되는 눈부신 발전을 이루게 된다. 이와 더불어 국내 터널 시공기술의 향상과 환경피해 최소화 노력에 따라 긴 터널이 급속히 증가하고 있는데, 현재 운영중인 1,000m 이상의 고속도로 터널이 3개소에 불과한데 비해 2003년 개통을 목표로 하고 있는 1,000m 이상 터널은 44개소에 이르고 있다.

• Journal of the Korean Geotechnical Society
• /
• v.39 no.10
• /
• pp.49-55
• /
• 2023

The discovery of lunar ice in the lunar polar region has fueled international interest in in situ resource utilization (ISRU) and the construction of lunar habitats. Unlike Earth's atmosphere, the Moon presents unique challenges, including frequent meteoroid impacts, direct exposure to space radiation, and extreme temperature variations. To safeguard lunar habitats from these threats, the construction of a protective shield is essential. Lunar regolith, as a construction material, offers distinct advantages, reducing transportation costs and ensuring a sustainable supply of raw materials. Moreover, it streamlines manufacturing, integration schedules, and enables easy repairs and modifications without Earth resupply. Adjusting the shield's thickness within the habitat's structural limits remains feasible as lunar conditions evolve. Although extensive research on protective shields using lunar regolith has been conducted, unresolved conflicts persist regarding shield requirements. This study conducts a comprehensive analysis of the primary lunar threats and suggests a minimum shield thickness of 2 m using lunar regolith. Furthermore, it outlines the necessary technology for the rapid construction of such protective shields.

• Journal of the Korea Concrete Institute
• /
• v.25 no.5
• /
• pp.517-528
• /
• 2013

The modular technology has been already applied in automotive industry, plant and shipbuilding industry. Recently, the modular technology was applied in bridge construction. The modular bridge is different from the existing precast bridges in terms of standardized design that the detailed design of members is omitted by using the standard modules; the design of the modular bridge is completed by only assembling the standard modules without design in member level. The girder-type precast modular bridge has been developed as a simply supported bridge. The girder-type precast modular bridge could be applied to the multi-span bridges through the continuity method. The continuity of the girder-type precast modular bridge is achieved by using the link slab which is easy to construction and appropriate to the rapid construction. The link slabs have been used as the type of reinforced concrete structure in US from the 1950's. In 2000's, the link slab using the engineered cementitious concrete (ECC link slab) has been developed. In this study, the RC type link slab which is more reproducible and economic relative to the ECC link slab was used for the continuity of the girder-type precast modular bridges, and the construction detail of RC type link slab was modified. In addition, the modified iterative design method of RC type link slab was proposed in this study. To verify the proposed design method, the flexural tests were conducted using the RC type link slab specimens. Also, the fatigue test using the mock-up specimen was conducted with cyclic loading condition up to two million cycles.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.16 no.6
• /
• pp.4267-4275
• /
• 2015

Prefabricated houses are fabricated at the factory for approximately 60 to 80% of the entire construction process, and assembled in the field. In the process of transporting and lifting, internal and external finishes of the unit module are concerned about damages. The purpose of this study is to improve the fixing equipment by analyzing load behavior. The improved fixing equipment would minimize the deformation of internal and external finishes. In order to develop the improved fixing equipment, transporting load on the fixing equipment is analyzed using Monte Carlo simulations, and structural performance is verified by the non-linear finite element analysis. Statistical analysis shows load distribution of unit module is similar with extreme value distribution. Based on the statistical analysis and Monte Carlo simulation, the maximum transporting load is 28.9kN and 95% confidence interval of transporting load is -1.22kN to 9.5kN. The nonlinear structural analysis shows improved fixing equipment is not destructed to the limit load of 35.3kN and withstands the load-bearing in the 95% confidence interval of transporting load.

• Proceedings of the KSR Conference
• /
• 2008.11b
• /
• pp.993-999
• /
• 2008

A girder height limitation is the critical parameter for rapid construction of bridge deck and construction space limitation especially in urban area such as high population area and high density habitats. A standard post-tensioned I-shaped concrete girder usually demands relatively higher girder height in order to retain sufficient moment arm between compression force and tensile force. To elaborate this issue, a small U-shaped section with wide flanges can be used as a possible replacement of I-shaped standard girder. This prestressed concrete box girder allows more flexible girder height adjustment rather than standard I-shaped post-tensioned girder plus additional torsion resistance benefits of closed section. A 30m-long, 1.7m-high and 3.63m-wide actual small prestressed concrete box girder is designed and a laboratory test for its static behaviors by applying 6,200kN amount of load in the form of 4-point bending test was performed. The load-deflection curve and crack patterns at different loading stage are recorded. In addition, to extracting the dynamic characteristics such as natural frequency and damping ratio of this girder, several excitation tests with artificial mechanical exciter with un-symmetric mass are carried out using operational frequency sweep-up. Nonlinear finite element analysis of this 4 point bending test under monotonic static load is investigated and discussed with aids of concrete damaged plasticity formulation using ABAQUS program.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.34 no.2
• /
• pp.355-365
• /
• 2014

Concrete-filled tubes (CFTs) have been used in civil engineering practices as a column of buildings and a bridge pier. CFTs have several advantages over the conventional reinforced concrete columns, such as rapid construction, enhanced buckling resistance, and inherited confinement effect. However, CFT component have not been widely used in civil engineering practice, since the design provisions among codes significantly vary each other. It leads to conservative design of CFT component. In this study, the design provisions of AISC and EC4 for CFT component were examined, based on the extensive test results conducted by previous researchers and finite element analysis results obtained in this study. Especially, the focus was made on the validation of P-M interaction curves proposed by AISC and EC4. From the results, it was found that the current design codes considerably underestimated the strength of CFT component under general combined axial load and bending. Finally, the modified P-M interaction curve was proposed and successfully verified.

• Journal of Korean Society of Steel Construction
• /
• v.24 no.6
• /
• pp.725-734
• /
• 2012

A new modular pier system using concrete filled circular steel tubes was suggested to realize modular bridge substructures for accelerated bridge construction. Structural details and connection details were proposed by connection multiple concrete filled tubes (CFT) for standardized products of fabrication, delivery and erection. Static tests were performed for the modular pier with suggested details under lateral load conditions for weak and strong axes. Due to the eccentricity by the bracing system, the modular pier showed 5.23 times higher flexural stiffness and 6 times greater flexural strength from the test. It is proper for the rational design to evaluate stress and deformation by frame modeling of the modular CFT pier. Structural capacity of the pier can be obtained by adjusting the spacing of the CFT columns. Design recommendations were derived from the test.