• 제목/요약/키워드: Dynamic Insulation

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Insulation Performance and Heating and Cooling Energy Consumption depending on the Window Reveal Depth in External Wall Insulation (외단열 벽체에서 창호 설치 위치에 따른 단열성능 및 냉난방 에너지 소비량)

  • Rhee, Kyu-Nam;Jung, Gun-Joo
    • Journal of the Architectural Institute of Korea Structure & Construction
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    • v.33 no.12
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    • pp.91-98
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    • 2017
  • In this study, the effect of window installation position in the residential building with the external insulation was numerically investigated in terms of insulation performance and heating/cooling energy consumption. For different window positions, 2-D heat transfer simulation was conducted to deduce the linear thermal transmittance, which was inputted to the dynamic energy simulation in order to analyze heating/cooling energy consumption. Simulation results showed that the linear thermal transmittance ranges from 0.05 W/mK to 0.7 W/mK, and is reduced as the window is installed near the external finish line. Indoor surface temperature and TDR analysis showed that the condensation risk is the lowest when the window is installed at the middle of the insulation and wall structure. It was also found that the window installation near the external finish can reduce the annual heating/cooling energy consumption by 12~16%, compared with the window installation near the interior finish. Although the window installation near the external finish can achieve the lowest heating/cooling energy consumption, it might lead to increased condensation risks unless additional insulation is applied. Thus, it can be concluded that the window should be installed near the insulation-wall structure junction, in consideration of the overall performance including energy consumption, condensation prevention and constructability.

The Analysis Results of Lightning Overvoltages by EMTP for Lightning Protection Design of 500kV Substations

  • Ju Hyung-Jun;Lee Heung-Ho
    • KIEE International Transactions on Power Engineering
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    • v.5A no.4
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    • pp.366-370
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    • 2005
  • To meet increasing power demand, 500 kV power systems are under consideration in the regions of some Middle Asian countries. As the power system voltage becomes higher, the cost for the power system insulation increases significantly. 500 kV transmission systems will become the basis of a region's power system and they require much higher system reliability. Consequently, by the methods of limiting overvoltages effectively, a reasonable insulation design and coordination must be accomplished. In particular, the Substations must be constructed to be of outdoor type. In order to determine the various factors for the insulation design, the EMTP (Electro-magnetic transient program) is used for the magnification of transient phenomena of the 500 kV systems in the planned network. In this paper, we will explain the calculation results of lightning overvoltages by the EMTP for lightning protection design for the 500 kV substations. To obtain reliable results, the multi-story tower model and EMTP/TACS model are introduced for the simulation of dynamic arc characteristics.

Thermal and Mechanical Properties of Epoxy/Micro- and Nano- Mixed Silica Composites for Insulation Materials of Heavy Electric Equipment

  • Park, Jae-Jun;Yoon, Ki-Geun;Lee, Jae-Young
    • Transactions on Electrical and Electronic Materials
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    • v.12 no.3
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    • pp.98-101
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    • 2011
  • A 10 nm nano-silica was introduced to a conventional 3 ${\mu}M$ micro-silica composite to develop an eco-friendly new electric insulation material for heavy electric equipment. Thermal and mechanical properties, such as glass transition temperature (Tg), dynamic mechanical analysis, tensile and flexural strength, were studied. The mechanical results were estimated by comparing scale and shape parameters in Weibull statistical analysis. The thermal and mechanical properties of conventional epoxy/micro-silica composite were improved by the addition of nano-silica. This was due to the increment of the compaction via the even dispersion of the nano-silica among the micro-silica particles.

A Novel Fast Open-loop Phase Locking Scheme Based on Synchronous Reference Frame for Three-phase Non-ideal Power Grids

  • Xiong, Liansong;Zhuo, Fang;Wang, Feng;Liu, Xiaokang;Zhu, Minghua;Yi, Hao
    • Journal of Power Electronics
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    • v.16 no.4
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    • pp.1513-1525
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    • 2016
  • Rapid and accurate phase synchronization is critical for the reliable control of grid-tied inverters. However, the commonly used software phase-locked loop methods do not always satisfy the need for high-speed and accurate phase synchronization under severe grid imbalance conditions. To address this problem, this study develops a novel open-loop phase locking scheme based on a synchronous reference frame. The proposed scheme is characterized by remarkable response speed, high accuracy, and easy implementation. It comprises three functional cascaded blocks: fast orthogonal signal generation block, fast fundamental-frequency positive sequence component construction block, and fast phase calculation block. The developed virtual orthogonal signal generation method in the first block, which is characterized by noise immunity and high accuracy, can effectively avoid approximation errors and noise amplification in a wide range of sampling frequencies. In the second block, which is the foundation for achieving fast phase synchronization within 3 ms, the fundamental-frequency positive sequence components of unsymmetrical grid voltages can be achieved with the developed orthogonal signal construction strategy and the symmetrical component method. The real-time grid phase can be consequently obtained in the third block, which is free from self-tuning closed-loop control and thus improves the dynamic performance of the proposed scheme. The proposed scheme is adaptive to severe unsymmetrical grid voltages with sudden changes in magnitude, phase, and/or frequency. Moreover, this scheme is able to eliminate phase errors induced by harmonics and random noise. The validity and utility of the proposed scheme are verified by the experimental results.

A Study on Dynamic Stiffness of Multi-layered Damping Materials (완충재의 구성에 따른 동탄성계수 변화에 관한 연구)

  • Im, Jung-Bin;Chung, Jin-Yeon;Kim, Kyoung-Woo;Jeong, Gab-Cheol
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2007.11a
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    • pp.1149-1152
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    • 2007
  • Many kind of damping materials are generally used on concrete slab in apartment building to reduce floor impact noise level. Lately, multi-layered damping material that is consist of several materials are used to improve the effect of floor impact noise insulation. In this study, dynamic stiffness of multi-layered damping material that is consist of common materials such as expanded polystyrene(EPS), expended polyethylene(EPE), ethylene vinyl acetate(EVA) and polyester was investigated. It was found that dynamic stiffness of multi-layered damping material could be estimated if know value of each layer that compose whole structure. And it was found that dynamic stiffness of whole structure did not change even if change order that build layer.

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A Study on Ventilation and Heat Transfer Coefficient of Passive Ventilation Skin (패시브환기외피의 통기성능 및 열관류율에 대한 연구)

  • Lee, Tae-Cheol;Son, Yu-Nam;Yoon, Seong-Hwan
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.24 no.9
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    • pp.679-684
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    • 2012
  • This paper aims to evaluate performances of ventilation and insulation of 6types PVS(Passive ventilation skin) by numerical simulation. The results are as follows. 1) The result of Performance of ventilation by pressure difference, it was shown that the amount of ventilation changed bigger under 1Pa and amount of ventilation increased according to increase opening area (${\alpha}A$). Although same opening area of PVS, it can predict that pressure differences cause ventilation differences. 2) In case of same opening area of PVS, however, it was changed the amount of ventilation each types of PVS that is distinguished opening area by flow coefficient. 3) Dynamic U-value that represents performance of insulation PVS was similar change upper ${\alpha}A40\;cm^2/m^2$, great change in casse of 0.1 Pa pressure difference. In case of ${\alpha}A10\;cm^2/m^2$, it was changed bigger under 0.3 Pa pressure difference, ${\alpha}A20\;cm^2/m^2$ of PVS was changed under 0.2 Pa pressure difference.

Transparent Insulation and Energy Saving in a School Building (학교건물(學校建物)의 에너지절약(節約)과 투명단열재(透明斷熱材))

  • Lee, Sung
    • Journal of the Korean Institute of Educational Facilities
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    • v.2 no.2
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    • pp.17-25
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    • 1995
  • Because of energy crisis and environment pollution, we have become more conscious of the need to conserve heat in buildings. In response to this need. new requirements have been developed for insulation and other matters relating to energy consumption. Among others, more promising is to use the energy that is all around us in the dynamic forces of nature:the wind, tides, waves, rivers, geothermal hot spots, and the sun. The problem is that we have not been forced to find the technological means to convert these natural energies into usable forms because it has been too easy simply to dig or pump our energy out of the ground. Now, the problem is not a shortage of energy itself, but a shortage of technology for converting the energy that lies aoo around us into usable forms. Energy-conversion technology is the real issue, and solar energy is one of the brightest and most promising frontiers in energy conversion. All buildings are wrapped in a skin. Generally skins protect the person in stay from rain, wind, dust, noise, cold, hot etc.. However, there are some skins that provide energy from given environment into the building. Out of aoo, transparent insulation material is one of these materials that most effectively satisfies this kind of envelope function. Since, there are no research on transparent insulation in Korea, it has been studied very actively in Europe and in America. Thus, in this thesis, we will theoratically study and analyze how the heat flows through a trans arrent insulated opaque wall of a school building in Korea. It will be an important information for the effective using guidelines of transparent insulation materials in Korea.

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Mechanical and Thermal Characteristics of Polyurethane Foam with Two Different Reinforcements and the Effects of Ultrasonic Dispersion in Manufacturing (이종 강화재를 첨가한 폴리우레탄 폼의 기계적 및 열적 특성과 제작 시 초음파 분산의 영향)

  • Kim, Jin-Yeon;Kim, Jeong-Dae;Lee, Jae-Myung
    • Journal of the Society of Naval Architects of Korea
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    • v.56 no.6
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    • pp.515-522
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    • 2019
  • Since Liquefied Natural Gas (LNG) is normally carried at 1.1 bar pressure and at -163℃, special Cargo Containment System (CCS) are used. As LNG carrier is becoming larger, typical LNG insulation systems adopt a method to increase the thickness of insulation panel to reduce sloshing load and Boil-off Rate (BOR). However, this will decrease LNG cargo volume and increase insulation material costs. In this paper, silica aerogel, glass bubble were synthesized in polyurethane foam to increase volumetric efficiency by improving mechanical and thermal performance of insulation. In order to increase dispersibility of particles, ultrasonic dispersion was used. Dynamic impact test, quasi-static compression test at room temperature (20℃) and cryogenic temperature (-163℃) was evaluated. To evaluate the thermal performance, the thermal conductivity at room temperature (20℃) was measured. As a result, specimens without ultrasonic dispersion have a little effect on strength under the compressive load, although they show high mechanical performance under the impact load. In contrast, specimens with ultrasonic dispersion have significantly increased impact strength and compressive strength. Recently, as the density of Polyurethane foam (PUF) has been increasing, these results can be a method for improving the mechanical and thermal performance of insulation panel.

Thermal Performance and Impact Resistance Evaluations of Composite Insulation Mat Reinforced Polyurethane Foam (복합 단열 매트 보강 폴리우레탄 폼의 열적 성능 및 내충격성 평가)

  • Hwang, Byeong-Kwan;Bae, Jin-Ho;Lee, Jae-Myung
    • Composites Research
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    • v.32 no.5
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    • pp.290-295
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    • 2019
  • In the present study, composite insulation mat was reinforced over polyurethane foam (PUF) to improve the thermal performance and impact resistance of the PUF applied to the liquefied natural gas carrier insulation system. The composite insulation mat used Kevlar, aerogel, and cryogel composite mat that can be applied in a cryogenic environment. The thermal conductivity was measured at $20^{\circ}C$ to investigate the thermal performance, and the drop impact test was carried out under impact energy of 30 J at $20^{\circ}C$, $-163^{\circ}C$ to investigate the impact resistance. The measured thermal performance was compared with neat PUF through effective thermal conductivity theoretical value. The shock resistance was evaluated of contact force, contact time, and absorb energy. In experimental results, cryogel composite mat was the best performance in terms of thermal performance, and aerogel composite mat was the best performance in terms of impact resistance.

Sloshing Impact Response Analysis for Insulation System of LNG CCS Considering Elastic Support Effects of Hull Structures (선체구조의 탄성지지 효과를 고려한 LNG 운반선 방열구조의 슬로싱 충격응답 해석법에 관한 연구)

  • Nho, In Sik;Ki, Min-Seok;Kim, Sung-Chan;Lee, Jang Hyun;Kim, Yonghwan
    • Journal of Ocean Engineering and Technology
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    • v.31 no.5
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    • pp.357-363
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    • 2017
  • The sloshing pressure acting on a membrane-type LNG CCS is a typical irregular impact load, and the structural response of a tank system induced by sloshing also shows very complex behavior, including fluid structure interaction. Therefore, it is not easy to accurately estimate the sloshing impact pressures and resulting structural response. Moreover, a huge time consuming process to deal with the enormous pressure data obtained during a model tank test and the following structural analysis would be inevitable. To reduce the computation time for structural analysis, in this study, a rational structural modeling strategy was considered, and a simplified scheme to analyze the dynamic structural responses of an LNG CCS was introduced, which was based on the concept of the linear combination of the triangular response functions obtained by a transient response analysis of structures under unit triangular impact pressure. A structural analysis of a real Mark III membrane type insulation system under the sloshing impact pressure time histories obtained by model tests was performed using the various proposed structural models and simplified analysis scheme. The results were investigated in detail, including the elastic support effects of the hull structure.