• Title/Summary/Keyword: Construction temperature

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Numerical Analysis of Helical Pile Behavior Varying Number and Diameter of Helices (헬릭스 개수 및 직경에 따른 헬리컬 파일 거동의 수치해석적 분석)

  • Bak, Jongho;Lee, Kicheol;Choi, Byeong-Hyun;Kim, Dongwook
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.39 no.1
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    • pp.211-217
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    • 2019
  • Oil extraction from oil sands, a non-traditional crude oil resource, is attracting attention as the oil price fluctuates due to recent economical and political issues. Many oil sands sites are mainly located in the polar regions. For plant construction to extract crude oil from oil sands in harsh environment of the polar regions, fast and simple installation of plant foundation is necessary. However, typically-used conventional foundations such as drilled shafts and driven piles are not suitable to construct under cold temperature and organic surface layers. In this study, helical piles enabling rapid and simple constructions using small rotary equipment without driving or excavation was considered. The helical pile consists of steel shaft and several helices attached to the steel shaft; therefore, the behavior of the helical pile depends on the number and shape of the helices. The effect of the helices' configuration (number and diameter of helices) on helical pile behavior was analyzed based on the numerical analysis results.

Waste heat recovery of recirculated MCFC using supercritical carbon dioxide power cycle (초임계 이산화탄소 사이클을 이용한 연료 재순환 MCFC의 폐열회수)

  • Lee, Jae Yoon;Ahn, Ji Ho;Kim, Tong Seop
    • Plant Journal
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    • v.15 no.2
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    • pp.42-45
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    • 2019
  • The molten carbonate fuel cell has a high temperature of waste heat and can constitute a bottoming cycle to increase the efficiency. Previous study used a bottoming cycle as steam turbine cycle. In this study, we are going to replace the bottoming cycle with a supercritical carbon dioxide power cycle. The system power was compared to consider replacing the bottoming cycle. As a result, the power of the supercritical carbon dioxide power cycle at the present development stage is lower than that of the steam turbine cycle, but theoretically, the power can be larger than the steam turbine cycle. If the supercritical carbon dioxide power cycle improves the isentropic efficiency of the turbine by 89%, the isentropic efficiency of the compressor by 83%, and the effectiveness of the recuperator by 0.9, the power can be same to the steam turbine cycle.

The influence of internal ring beams on the internal pressure for large cooling towers with wind-thermal coupling effect

  • Ke, Shitang;Yu, Wei;Ge, Yaojun;Zhao, in;Cao, Shuyang
    • Wind and Structures
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    • v.28 no.1
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    • pp.1-17
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    • 2019
  • Internal ring beams are primary components of new ring-stiffened cooling towers. In this study, numerical simulation of the internal flow field of a cooling tower with three ring beams under wind-thermal coupling effect is performed. The studied cooling tower is a 220-m super-large hyperbolic indirect natural draft cooling tower that is under construction in China and will be the World's highest cooling tower, the influence of peripheral radiators in operating cooling tower is also considered. Based on the simulation, the three-dimensional effect and distribution pattern of the wind loads on inner surface of the cooling tower is summarized, the average wind pressure distributions on the inner surface before and after the addition of the ring beams are analyzed, and the influence pattern of ring beams on the internal pressure coefficient value is derived. The action mechanisms behind the air flows inside the tower are compared. In addition, the effects of internal ring beams on temperature field characteristics, turbulence kinetic energy distribution, and wind resistance are analyzed. Finally, the internal pressure coefficients are suggested for ring-stiffened cooling towers under wind-thermal coupling effect. The study shows that the influence of internal stiffening ring beams on the internal pressure and flow of cooling towers should not be ignored, and the wind-thermal coupling effect should also be considered in the numerical simulation of cooling tower flow fields. The primary conclusions presented in this paper offer references for determining the internal suction of such ring-stiffened cooling towers.

Effects of Chemical Composition of Ca(OH)2 and Precursors on the Properties of Fast-Curing Geopolymers (Ca(OH)2와 전구체의 화학 조성이 고속경화 지오폴리머의 물성에 미치는 영향)

  • Ko, Hyunseok;Noh, Jung Young;Lim, Hyung Mi
    • Korean Journal of Materials Research
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    • v.29 no.11
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    • pp.690-696
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    • 2019
  • Geopolymer is an alumina silicate-based ceramic material that has good heat-resistance and fire-resistance; it can be cured at room temperature, and thus its manufacturing process is simple. Geopolymer can be used as a reinforcement or floor finish for high-speed curing applications. In this manuscript, we investigate a high-speed curing geopolymer achieved by adding calcium to augment the curing rate. Metakaolin is used as the main raw material, and aqueous solutions of KOH and $K_2SiO_3$ are used as the activators. As a result of optimizing the high bending strength as a target factor for geopolymers with $SiO_2/Al_2O_3$ ratio of 4.1 ~ 4.8, the optimum ranges of the active agent are found to be $0.1{\leq}K_2O/SiO_2{\leq}0.4$ and $10{\leq}H_2O/K_2O{\leq}32.5$, and the optimum range of the curing accelerator is found to be $$0.82{\leq_-}Ca(OH)_2/Al_2O_3{\leq_-}2.87$$. The maximum flexural strength is found to be 1.35 MPa at $Ca(OH)_2/Al_2O_3=2.82$, $K_2O/SiO_2=0.3$, and $H_2O/K_2O=11.3$. The physical and thermal properties are analyzed to validate the applicability of these materials as industrial insulating parts or repairing finishing materials in construction.

Development of Optimum Design Method for Geothermal Performance based on Energy Simulation (지열 성능해석 시뮬레이션에 기반한 최적 설계 수법 개발)

  • Moon, Hyeongjin;Kim, Hongkyo;Nam, Yujin
    • Journal of the Architectural Institute of Korea Structure & Construction
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    • v.35 no.3
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    • pp.43-48
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    • 2019
  • Since the revision of the Rationalization of Energy Use Law, the spread of new and renewable energy in buildings has been promoted. In addition, the production of electric power and thermal energy is an important issue in the change of energy paradigm centered on the use of distributed energy. Among them, geothermal energy is attracting attention as a high-performance energy-saving technology capable of coping with heating / cooling and hot water load by utilizing the constant temperature zone of the earth. However, there is a disadvantage that the initial investment cost is high as a method of calculating the capacity of a geothermal facility by calculating the maximum load. The disadvantages of these disadvantages are that the geothermal energy supply is getting stagnant and the design of the geothermal system needs to be supplemented. In this study, optimization design of geothermal system was carried out using optimization tool. As a result of the optimization, the ground heat exchanger decreased by 30.8%, the capacity of the heat pump decreased by 7.7%, and the capacity of the heat storage tank decreased by about 40%. The simulation was performed by applying the optimized value to the program and confirmed that it corresponds to the load of the building. We also confirmed that all of the constraints used in the optimization design were satisfied. The initial investment cost of the optimized geothermal system is about 18.6% lower than the initial investment cost.

A Study on the Proper Illuminance Considering the Task Amenity of the Occupant in the Office Space (사무공간의 재실자의 작업면 쾌적성을 고려한 적정조도 도출)

  • Kim, In-Hye;Kim, Sung-Kyung;Hong, Won-Hwa
    • Journal of the Architectural Institute of Korea Structure & Construction
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    • v.36 no.3
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    • pp.159-167
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    • 2020
  • For modern people who spend most of their time indoors, the indoor environment is very important. The efficiency of work depends on the amenity level of the occupants who use the office space. Therefore, the experiment was conducted to derive the proper illuminance according to the amenity level of the occupants. The experiment was conducted in an office in Chilgok County for 6 days. The illuminance of the indoor was changed every day, the feeling brightness of the occupants was measured every 10 minutes, the eye fatigue was measured every 30 minutes, and the overall illuminance and the work surface illuminance were measured every hour. Experimental results show that the feeling brightness is different depending on the position of the occupants. Also, it was found that the brightness survey preferred by the occupants required more proper illuminance than the brightness. In addition, it is considered that there is a correlation with indoor temperature and humidity as the eye fatigue of occupants. Brightness preference by time of day was analysis from feeling brightness of occupants and preference brightness of occupants, and then it was analyzed like eye fatigue to derive proper illuminance per hour. Based on these results, it can be utilized for improvement of eye amenity existing office space.

An Analysis on Micro-climate Characteristic of Apartments in Beijing, China Using ENVI-met Simulation (ENVI-met를 이용한 중국 베이징 아파트 하절기 미기후 특성 분석)

  • Wu, Jin-Dong;Lee, Jun-Hoo;Yoon, Seong-Hwan
    • Journal of the Architectural Institute of Korea Structure & Construction
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    • v.35 no.8
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    • pp.169-176
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    • 2019
  • The purpose of this study was to analyze outdoor thermal comfort of apartments planning characteristic of pedestrian height in Beijing, China. Selecting 322 apartment complexes with more than 1000 households and more than 10 buildings(including 10 buildings), mainly in Chaoyang District and Tongzhou District to select 32 basic layout types and then 12 typical layout types were select in 32 basic layout types. Finally, the simulation was conducted for the 12 typical layout types using the micro-climate model ENVI-met to evaluate the wind environment, the thermal environment and the comfort. The results of this study as follows: In the parallel arrangement, it has the best outdoor thermal comfort of Slab-East-Parallel(S/E/P). Next is Slab-South-Parallel(S/S/P), Tower-South-Parallel(T/S/P) in turn. In the stagger arrangement, Mixture-South-North and South Stagger-1(M/S/NSS-1) has the best outdoor thermal comfort and Slab-South-North and South Stagger(S/S/NSS), Tower-South-North and South Stagger(T/S/NSS), Mixture-South-North and South Stagger-3(M/S/NSS-3), Mixture-South-North and South Stagger-4(M/S/NSS-4), Mixture-South-North and South Stagger-2(M/S/NSS-2) in turn. In the cluster arrangement, Mixture-Mixture-Cluster-2(M/M/C-2) has the best outdoor thermal comfort and Mixture-Mixture-Cluster-3(M/M/C-3), Mixture-Mixture-Cluster-1(M/M/C-1) in turn. Due to the low wind speed and high air temperature, it is necessary to consider the layout types that can form the wind road at first, such as Mixture-South-North and South Stagger-1(M/S/NSS-1), Slab-South-North and South Stagger(S/S/NSS) and so on.

The Analysis of Thermal Conductivity and Basic Quality Performances of Decoration Wood-based Flooring Board Laminated with PVC Surface Decoration Materials (PVC 표면치장재를 적층한 치장목질마루판의 열특성 및 기초 품질성능 분석)

  • Park, Cheul-Woo
    • Journal of the Architectural Institute of Korea Structure & Construction
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    • v.34 no.1
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    • pp.53-60
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    • 2018
  • For test on flooring board laminated with PVC decoration materials in order to replace the current surface materials such as HPL in decoration wood-based flooring board. the Results of comparison and analysis are as follows: For thermal conductivity, flooring board decorated with PVC did not show huge differences when temperature was rising and lowering compared to the flooring materials laminated with the existing HPL surface materials. It seems the most meaningful results for using it as indoor flooring materials. That is, in Korea where there is the culture focusing on ondol heating, use amount of heat energy and efficiency of flooring materials are very important and sensitive issues, involving immediately with household economy of final consumers, and it might be a criteria to judge basic performances required as flooring materials. As a result of the analysis on mandatory durability test items such as abrasion resistance, absorption width expansion rate, impact resistance, surface hardness, and impact absorption for flooring materials, compared to flooring board laminated with general HPL surface decoration materials, decoration wood-based flooring board laminated with PVC surface decoration materials which is higher abrasion resistance with smaller transformation and has better durability and impact absorption of the surface, is available for actual application as indoor flooring board, and for replacing surface decoration materials impregnated with heat-hardened resion such as HPL.

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.

Design and Analysis of Cell Controller Operation for Heat Process (열공정에 대한 셀 콘트롤러 운영의 설계와 해석)

  • So, Ye In;Jeon, Sang June;Kim, Jeong Ho
    • Journal of Platform Technology
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    • v.8 no.2
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    • pp.22-31
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    • 2020
  • The construction and operation of industrial automation has been actively taking place from manufacturing plan to production for improving operational efficiency of production line and flexibility of equipment. ISO/TC184 is standardizing on operating methods that can share information of programmable device controllers such as PLC and IoT that are geographically distributed in the production line. In this study, the design of the cell controller consists of PLC group and IoT group that perform signals such as temperature sensors, gas sensors, and pressure sensors for thermal processes and corresponding motors or valves. The operation and analysis of the cell controller were performed using SDN(Software Defined Network) and the three types of process services performed in thermal processes are real-time transmission service, loss-sensitive large-capacity transmission service, and normal transmission service. The simulation result showed that the average loss rate improved by about 17% when the traffic increased before and after the application of the SDN route technique, and the delay in the real-time service was as low as 1 ms.

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