• Earthquakes and Structures
• /
• v.16 no.5
• /
• pp.625-639
• /
• 2019

The concept of the combined seismic and energy retrofitting of existing reinforced concrete (RC) buildings was examined in this paper through a number of case studies conducted on model buildings (simulating buildings of the '60s-'80s in southern Europe) constructed according to outdated design standards. Specifically, seismic and thermal analyses have been conducted prior to and after the application of selected retrofitting schemes, in order to quantify the positive effect that retrofitting could provide to RC buildings both in terms of their structural and energy performance. Advanced materials, namely the textile reinforced mortars (TRM), were used for providing seismic retrofitting by means of jacketing of masonry infills in RC frames. Moreover, following the application of the TRM jackets, thermal insulation materials were simultaneously provided to the RC building envelope, exploiting the fresh mortar used to bind the TRM jackets. In addition to the externally applied insulation material, all the fenestration elements (windows and doors) were replaced with new high energy efficiency ones. Afterwards, an economic measure, namely the expected annual loss (EAL) was used to evaluate the efficiency of each retrofitting method, but also to assess whether the combined seismic and energy retrofitting is economically feasible. From the results of this preliminary study, it was concluded that the selected seismic retrofitting technique can indeed enhance significantly the structural behaviour of an existing RC building and lower its EAL related to earthquake risks. Finally, it was found that the combined seismic and energy upgrading is economically more efficient than a sole energy or seismic retrofitting scenario for seismic areas of south Europe.

• Journal of the Korean Solar Energy Society
• /
• v.23 no.4
• /
• pp.63-70
• /
• 2003

It is very important to improve the insulation performance of curtain wall anchoring unit since it is composed of materials with high thermal conductivity, such as aluminium, steel and so on. This study aims to evaluate the heating energy performance and economical efficiency of various alternatives which are different in position and material of insulation. As results, alternative of inserting the urethane washer & pad and coating the anchoring unit with urethane foam can improve the heating energy performance and L.C.C(Life Cycle Cost) by 6.33% and 0.95%, respectively, as compared with the existing case.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2018.11a
• /
• pp.19-20
• /
• 2018

As energy related problems continue to arise, Korea's thermal insulation market for the zero energy homes is also demanding major changes, but there are no realistic countermeasures. Also, interest in inorganic insulation is growing as damage from multifamily housing fire using flammable insulation materials is increasing. On the other hand, many studies have been conducted on lightweight foam concrete, which implies a sufficient possibility as an insulation material by generating a large amount of air bubbles. However, studies of existion bubble concrete are not quantified by the experimental difficulty of using bubbles when compared. Therefore, in this study, the change in strength due to air pressure using a bubble foam, one of the types of air bubbles for the development of light foam concrete.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2009.11a
• /
• pp.155-155
• /
• 2009

This paper introduces the findings of a detailed study on breakdown voltage strength under DC voltage and the development of HVDC cable. Recently, Nano-fillers are attracting attentions of many researchers and engineers, since they seem to bring higher potentials for advancement of electrical insulating properties as nano-composites. Additives and fillers are often adopted to polymeric materials for improving insulating and machanical properties. We have improved the polymer composition and developed a new insulation material for HVDC cable. Each specimen blended at LDPE1 to antioxidant, LDPE2 to antioxidant, pure XLPE was manufactured respectively. The insulation performances of the proposed insulator were compared with specimens blended at nano powders. DC breakdown strength of LDPE1 specimen at 90[$^{\circ}C$] was higher than other specimens. The experimental results show that polar groups intorduced in moleculars chains of blended specimen plays an important role in enhancement of thermal conductivity.

• Journal of the Society of Naval Architects of Korea
• /
• v.55 no.5
• /
• pp.448-455
• /
• 2018

Glass wool is an eco-friendly materials that is manufactured through a continuous process by processing waste glass. This materials is low cost compared with another materials and has excellent thermal conductivity. For this reason, glass wool is installed as insulation system for LNG carriers and as insulation of building wall as well as various industries. The mechanism of insulation of glass wool is the conduction of the wool itself and convection by space between fibers. Therefore, in order to develop the enhanced thermal conductivity of glass wool is necessary to reduce its own conduction or to insert additional material after manufacturing as well as prevent convection. In this respect, many researchers have been actively studying to decrease thermal conductivity of polyurethane foam using by inserted glass wool or change the chemical component of glass wool. However, many research are aiming reduction of glass wool itself. This study focus on post-processing and inserted different materials; silica-aerogel, kevlar fiber 1mm, 6mm and glass bubble. Experimental results show that the thermal conductivity almost decreases with the addiction of glass bubble and silica aerogel.

• Journal of the Korean Solar Energy Society
• /
• v.31 no.2
• /
• pp.47-52
• /
• 2011

Currently, Exterior wall's U-value about building envelope is 0.36 W/$m^2K$(Central Region), but window's one is 2.1 W/$m^2K$ according to air gap of glazing, filling gas, coating and type of windows. The door"s one is 1.6~5.5 W/$m^2{\cdot}K$ depending on material and configuration of door. As such, energy loss per unit of door is considerably larger like windows. The door for the recognition was relatively low because energy loss through the door is relatively small compared to window area. In this paper, thermal performance was analyzed through simulation targeting the door which has thermal break that can improve the insulation performance and doesn't have one. As a results of simulations, case1 was calculated as the average of 1.63 w/m2k and case 2 was calculated as the average of 4.14 w/m2k. The thermal performance of door depends on the type and condition of insulations. As a results of final simulations, Case1 was calculated as 1.06 w/m2k and Case2 was calculated as 1.27 w/m2k. As a results of the experiments, thermal performance of case 1 was measured as 1.28 w/m2k. Error between experiments and simulations is considered problems encountered when creating the samples. The effect of door frame on the overall thermal performance is slight because it's a small proportion of the door frame.

• Applied Chemistry for Engineering
• /
• v.27 no.1
• /
• pp.35-38
• /
• 2016

In this study, the mica used as a thermal-insulation material was modified with a silane coupling agent, octyltriethoxysilane (OTES), to improve its hydrophobicity. The modified mica was characterized using FT-IR spectrometer, water wettability test, and water contact angle measurement. The analysis exhibits that OTES for the modified mica sample was well bonded chemically and drastically enhanced the hydrophobicity. The reflectance observed as 73.9% (mica) and 86.4% (OTES/mica), respectively, for OTES/mica was improved about 12.5% before any modifications. Also the modified mica sample showed $7.2^{\circ}C$ decrease in the thermal-insulation performance of cool paints compared to that of using unmodified mica, indicating that the modification of mica with silane coupling agents could be effective in enhancing the thermal-insulation performance of the cool paint.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.21 no.5
• /
• pp.90-98
• /
• 2007

The objective of this investigation was to reveal the cause of the faulted cable(LV URD(low voltage underground) cable). For the analysis, various types or equipments such as external pattern, thermal pattern, surface structure, thermal analysis, and property distribution were deployed. The international standards and the specification provided by the manufacturer of faulted cable were examined whether it fit the standards. The summary is as follows. (1) Discovered as a factor lowering insulation performance of the faulted cable: minimum thickness of the insulation layer specified by IEC 60502-1 and IEC 60811-1-1 was not fit. (2) Infrared absorption peaks measured by FT-IR spectrometer revealed that the measurements made for the same material did not conform and it is an important basis for proving heterogeneous composition of the insulation material. (3) It was found that PVC bedding was thermally fragile and therefore long term exposure at the site could cause similar fault pattern.

• Journal of the Korea Safety Management & Science
• /
• v.12 no.3
• /
• pp.121-128
• /
• 2010

This is to show some basic data for introducing both circulated aggregate and recycled powder producing waste concrete. Standard-mixing design for 24MPa has been basically used and added and replaced normal aggregate with recycled powder made of waste concrete. In addition, polycarboxylate high-range water reducing agent has been used because recycled powder is missing adhesive strength and it is not compare with cement's adhesive strength. Compressive strength with powder mixture of 2%, 4%, 6%, 8%, and 10% has been decreased down to 80% of normal concrete material strength without recycled powder mixture. $200^{\circ}C$, $400^{\circ}C$ and $600^{\circ}C$ heated concrete were compressively tested in order to find out concrete strength resistant to high temperature. heat capacity was also tested, based on the expectancy of its low conductivity. In addition, thermal conduction test was tested in order to find out concrete insulation. According to this test, when concrete was tested by fire resistance, it using the circulation aggregate was same resulted by concrete using the natural aggregate. also, recycle powder was not effecting insulation performance. but it is fit to standard on concrete insulation of building law.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1998.06a
• /
• pp.227-230
• /
• 1998

The effects of post curing conditions on thermal properties of alumina filled epoxy resin system DGEBA/MDA/SN were investigated. As the post curing time increased at 15$0^{\circ}C$, the glass transition temperature increased from 121 to 124, slightly. As the heating rate increased, high thermal decomposing temperature (T$_{d}$) and most decomposing temperature (T$_{p}$) increased. For the case of post-cured system at 15$0^{\circ}C$ for 4 days showed lower values than virgin system. At the post curing condition the system must have been thermally degraded.ded.