• Title/Summary/Keyword: energy direction

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Influence of Temperature on Chloride Ion Diffusion of Concrete (콘크리트의 염화물이온 확산성상에 미치는 온도의 영향)

  • So, Hyoung-Seok;Choi, Seung-Hoon;Seo, Chung-Seok;Seo, Ki-Seog;So, Seung-Young
    • Journal of the Korea Concrete Institute
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    • v.26 no.1
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    • pp.71-78
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    • 2014
  • The long term integrity of concrete cask is very important for spent nuclear fuel dry storage system. However, there are serious concerns about early deterioration of concrete cask from creaking and corrosion of reinforcing steel by chloride ion because the cask is usually located in seaside, expecially by combined deterioration such as chloride ion and heat, carbonation. This study is to investigate the relation between temperature and chloride ion diffusion of concrete. Immersion tests using 3.5% NaCl solution that were controlled in four level of temperature, i.e. 20, 40, 65, and $90^{\circ}C$, were conducted for four months. The chloride ion diffusion coefficient of concrete was predicted based on the results of profiles of Cl- ion concentration with the depth direction of concrete specimens using the method of potentiometric titration by $AgNO_3$. Test results indicate that the diffusion coefficient of chloride ion increases remarkably with increasing temperature, and there was a linear relation between the natural logarithm values of the diffusion coefficients and the reciprocal of the temperature from the Arrhenius plots. Activation energy of concrete in this study was about 46.6 (W/C = 40%), 41.7 (W/C = 50%), 30.7 (W/C = 60%) kJ/mol under a temperature of up to $90^{\circ}C$, and concrete with lower water-cement ratio has a tendency towards having higher temperature dependency.

Microseismic Monitoring for KAERI Underground Research Tunnel (KURT 미소진동 모니터링)

  • Kim, Kyung-Su;Bae, Dae-Seok;Koh, Yong-Kwon;Kim, Jung-Yul
    • The Journal of Engineering Geology
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    • v.19 no.2
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    • pp.139-144
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    • 2009
  • The microseismic monitoring system with wide range of frequency has been operating in real time and it is remotely monitored at indoor and on-site for one year. This system was constructed and established in order to secure the safe and effective operation of the KAERI Underground Research Tunnel(KURT). For one year monitoring work, total 14 events were recorded in the vicinity of the KURT, and the majority of events are regarded as ultramicroseismic earthquake and artificial impacts around the tunnel. The major event is the magnitude 3.4 earthquake which was centered around Gongju city, Chungnam Province. It means that there is no significant evidence of high frequency microseismic event, which is associated with fracture initiation and/or propagation in the rock mass and shotcrete. Three components sensor was applied in order to analyze and define the direction of vibration as well as an epicenter of microseismic origin, and also properly designed and installed in a small borehole. This monitoring system is able to predict the location and timing of fracturing of rock mass and rock fall around an undreground openings as well as analysis on safety of various kinds of engineering structures such as nuclear facilities and other structures.

Design Parameters of Riverbed Filtration Estimated from Geochemical Data (지구화학적 해석을 이용한 하상여과 설계인자에 대한 연구)

  • Cho, Kang-Hee;Kim, Bong-Ju;Ahn, Joong-Hyuk;Rhim, Ki-Sung;Choi, Nag-Choul;Park, Cheon-Young
    • The Journal of Engineering Geology
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    • v.23 no.4
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    • pp.493-502
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    • 2013
  • This study investigates the design parameters for riverbed filtration (RBF) based on the geochemistry of river water and groundwater. The study area consists of alluvium, and the area is readily affected by non-point sources of chemical contaminants in the surface environment; this is expected to affect the design parameters for RBF. River and groundwater samples were collected at three points along the river flow and at nine points along a transect normal to the river, respectively. The geochemical data indicate that the sources of individual chemical contaminants are industrial facilities and agricultural activity near the study area. In addition, The samples are mainly Ca-Na-$HCO_3$, Ca-Cl, and Ca-$HCO_3$-Cl type waters. The design parameters of RBF in the study area should consider K, $HCO_3$, $NO_3$, and Cl. We divided the study area into three regions based on the concentrations of stable nitrogen isotopes: Region A, the origin of the river and denitrification; Region B, denitrification in the flow direction of tributaries; and Region C, the origin of natural soil, sewage, and anthropogenic pollution.

Evaluation of the State of Rocks in Load Steps by Low-frequency Ultrasonic Flaw Detection (저주파 결함 탐지법에 의한 하중 단계에 따른 암석 내부의 상태 평가)

  • Kang, Seong-Seung;Kim, Jongheuck;Noh, Jeongdu;Na, Tae-Yoo;Jang, Hyongdoo;Ko, Chin-Surk
    • The Journal of Engineering Geology
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    • v.27 no.1
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    • pp.51-58
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    • 2017
  • The purpose of this study was to quantitatively evaluate the state of rocks in load steps by using the low-frequency ultrasonic flaw detection method. The initial Vp-velocities measured with a CND tester were in the order of Z-axis < X-axis < Y-axis, with 1687.5 m/s along the X-axis, 1690.7 m/s along the Y-axis, 1548.3 m/s along the Z-axis, and an average of 1642.2 m/s. The overall average of the Q vlaues, measured with a Silver Schmidt hammer, was 62.6, which corresponds to a uniaxial compressive strength of ~105 MPa. The Vp-velocity, measured with a low-frequency ultrasonic flaw detector at load steps of 50%, 60%, 70%, and 80%, typically decreases in the order of X-axis < Y-axis < Z-axis with increasing load steps. This oder contrasts with that of the initial Vp-velocities. As the load step increases the factors that reduce the Vp-velocity in the X-axis direction are more influential than those in the Y-axis or Z-axis directions. This indicates that the initial state of rocks can vary and is dependent on the stress state.

A Study on the Airflow Distribution in the Diagonal Ventilation Circuit for the Design of a High Level Radioactive Waste Repository (고준위 방사성 폐기물 처분장 설계를 위한 Diagonal 환기 회로 내 공기량 분배에 관한 연구)

  • Hwang, In-Phil;Choi, Heui-Joo;Roh, Jang-Hoon;Kim, Jin
    • Tunnel and Underground Space
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    • v.22 no.3
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    • pp.173-180
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    • 2012
  • In this study, diagonal ventilation circuits that are advantageous in air flow direction control were studied. Based on the results of the study, it could be seen that air volumes in diagonal ventilation circuits could also be calculated using numerical formulas or programs if the air volumes and air flow directions to be infused into diagonal branches are determined in advance as with other serial/parallel circuits. To apply the results, design plans for high level radioactive waste repositories applied with diagonal ventilation circuits and parallel ventilation circuits. To compared the each design plans and obtain expected operation results, ventilation network simulations were conducted through the Ventsim program which is a ventilation networking program. Based on the results, in the case of diagonal repositories that was expected to cause great increases in resistance, fan pressure was 1570 pa, total flux was 84 $m^3/s$, fan efficiency was 76.4%, fan power consumption was 181.2 kW and annual fan operating costs were 178,710,838 and thus maximum around 8% differences were shown in pressure and flux values and a difference of around 1.5% was shown in terms of operating costs.

An Interoperable Mapping Model between SEP 2.0 & OpenADR 2.0b for ICT Grid Convergence (ICT 전력 융합을 위한 SEP 2.0과 OpenADR 2.0b간의 상호운용 매핑 모델)

  • Choi, Min-Young;Lee, June-Kyoung;Lee, Kyoung-Hak
    • Journal of the Korea Convergence Society
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    • v.8 no.8
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    • pp.41-49
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    • 2017
  • The 'NIST Framework and Road Map for Smart Grid Interoperability Standards' proposes an architecture framework to secure the direction of development and standard interoperability of smart grid and provides a list of identified standard, standard cyber security strategies, and certification framework. In particular, SEP 2.0 and OpenADR 2.0 are the examples. SEP 2.0 and OpenADR 2.0 can functionally link HEMS and Smart Grid, but interoperability standards between the two protocols are not planned in above document. The OpenADR Alliance also announced that work is underway to define mapping tables for interoperability between OpenADR 2.0 and SEP 2.0, but no information is yet available. Therefore, In this paper, in developing energy efficiency improvement HEMS, we propose a mapping model that supports syntactic and semantic founded interoperability between SEP 2.0 and OpenADR 2.0b for ICT grid convergence based on the standard specification document of each protocol and confirmed through an example of the semantic mapping function based on the demand response service scenario.

Design and performance evaluation of fish-luring system using the air-cooled LED lamp for jigging and angling boat (채낚기 어선용 공랭식 LED 집어시스템의 설계 및 성능평가)

  • Bae, Bong-Seong;Park, Byoung-Jae;Jeong, Eui-Cheol;Yang, Yong-Su;Park, Hae-Hoon;Chun, Young-Yull;Chang, Dae-Soo
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.45 no.2
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    • pp.85-95
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    • 2009
  • The fishing lamp is a fishing gear that gathers fish at night. But the cost of oil, which is used to light fishing lamp, has been risen significantly up to 30-40% of total fishing costs. Therefore it is very urgent to develop an energy economical fishing lamp in order to solve the business difficulties of fisheries. Under this background, this research aims at developing a fishing lamp for squid jigging and hairtail angling fishery using the LED, which has excellent energy efficiency and durability. The LED fishing lamp developed can be controlled to fix a fit direction of fish shoal deep because a fishing lamp can be adjustable up and down directions. One unit of fishing lamp has about an 80Watt capacity and the frame of fishing lamp is made of aluminium to emit generated heat of LED to outside. The LED lamp developed was highly durable, only 5.7% of emitting efficiency decreased for 18 months. The illuminance of a unit LED lamp was 2,070lux at 1m and 21lux at 10 m distance, and the intensity of LED lamp system emitted 2,580lux and 400lux at the respective distances. After development of this fishing lamp, 100 units are installed on operating fishing vessels. Experimental results show that energy consumption of squid jigging and hairtail angling was reduced by 40% and 87%, respectively. In conclusion, our methods showed elevated fishing power, compared with traditional fishing method: 37.7% for squid jigging and 24.5% for hairtail angling.

The Alignment of Liquid Crystals on the Film Surfaces of Soluble Aromatic Polyimides Bearing t-Butylphenyl and Trimethylsilylphenyl Side Groups

  • Hahm, Suk-Gyu;Jin, Kyeong-Sik;Park, Sam-Dae;Ree, Moon-Hor;Kim, Hyung-Sun;Kwon, Soon-Ki;Kim, Yun-Hi
    • Macromolecular Research
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    • v.17 no.12
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    • pp.976-986
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    • 2009
  • With the study goal of firstly elucidating the anisotropic interactions between oriented polymer chain segments and liquid crystal (LC) molecules, and secondly of determining the contributions of the chemical components of the polymer segments to the film surface topography, LC alignment, pretilt, and anchoring energy, we synthesized three dianhydrides, 1,4-bis(4'-t-butylphenyl)pyromellitic dianhydride (BBPD), 1,4-bis(4'-trimethylsilylphenyl)pyromellitic dianhydride(BTPD), and 2,2'-bis(4"-tert-butylphenyl)-4,4',5,5'-biphenyltetracarboxylic dianhydride (BBBPAn), and a series of their organosoluble polyirnides, BBPD-ODA, BBPD-MDA, BBPD-FDA, BTPD-FDA, and BBBPAn-FDA, which contain the diamines 4,4'-oxydianiline (ODA), 4,4'-methylenediamine (MDA), and 4,4'-(hexafluoroisopropylidene)dianiline (FDA). All the polyimides were determined to be positive birefringent polymers, regardless of the chemical components. Although all the rubbed polyimide films exhibited microgrooves which were created by rubbing process, the film surface topography varied depending on the polyimides. In all the rubbed films, the polymer chains were unidirectionally oriented along the rubbing direction. However, the degree of in-plane birefringence in the rubbed film varied depending on the polyimides. The rubbing-aligned polymer chains in the polyimide films effectively induced the alignment of nematic LCs along their orientation directors by anisotropic interactions between the preferentially oriented polymer chain segments and the LCs. The azimuthal and polar anchoring energies of the LCs ranged from $0.45{\times}10^{-4}\;-\;1.37{\times}10^{-4}\;J/m^2$ and from $0.86{\times}10^{-5}\;-\;4.26{\times}10^{-5}\;J/m^2$, respectively, depending on the polyimides. The pretilt angles of the LCs were in the range $0.10-0.62^{\circ}$. In summary, the soluble aromatic polyimides reported here are promising LC alignment layer candidates for the production of advanced LC display devices.

A Study of Cold Flow Characteristics of a Flue Gas Recirculation Burner using Coanda Nozzles (코안다 노즐을 이용한 배기가스 재순환 버너의 냉간 유동 특성에 관한 연구)

  • Ha, Ji Soo;Park, Chan Hyuk;Shim, Sung Hun;Jung, Sang Hyun
    • Journal of Energy Engineering
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    • v.25 no.4
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    • pp.152-158
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    • 2016
  • Nitrogen oxide is generated by the chemical reaction of oxygen and nitrogen in higher temperature environment of combustion facilities. The NOx reduction equipment is generally used in the power plant or incineration plant and it causes enormous cost for the construction and maintenance. The flue gas recirculation method is commonly adopted for the reduction of NOx formation in the combustion facilities. In the present study, the computational fluid dynamic analysis was accomplished to elucidated the cold flow characteristics in the flue gas recirculation burner with coanda nozzles in the flue gas recirculation pipe. The inlet and outlet of flue gas recirculation pipes are directed toward the tangential direction of circular burner not toward the center of burner. The swirling flow is formed in the burner and it causes the reverse flow in the burner. The ratio of flue gas recirculation flow rate with the air flow rate was about 2.5 for the case with the coanda nozzle gap, 0.5mm and it was 1.5 for the case with the gap, 1.0mm. With the same coanda nozzle gap, the flue gas recirculation flow rate ratio had a little increase when the air flow rate changes from 1.1 to 2.2 times of ideal air flow rate.

Modification of Balancing Piston for Trimming of Impeller Diameter for Maintaining Axial-Thrust Balance in Low-Specific-Speed Multistage Centrifugal Pumps (저비속도 원심 회전차 외경가공에 따른 축추력 불균형을 감쇄시키기 위한 평형 피스톤 수정방안에 관한 고찰)

  • Yoo, Il-Su;Park, Moo-Ryong;Yoon, Eui-Soo
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.35 no.9
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    • pp.875-882
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    • 2011
  • In the present study, the imbalance in the axial-thrust and variation in the volumetric efficiency that occurred during the trimming of impeller diameter were investigated. The present study was focused on low-specific-speed multistage centrifugal pumps with a balancing piston as the balancing mechanism. The effects of impeller trimming on the axial-thrust balance in multistage pumps with horizontal and vertical axes were compared. The results showed that impeller trimming resulted in an additional axial-thrust acting in direction of pump inlet. The axial-thrust imbalance due to impeller trimming was more severe in the vertical-axis pumps than in the horizontal-axis pumps. The rate of increase in the diameter of the balancing piston, which was proportional to the rate of impeller trimming, was evaluated to maintain the axial-thrust balance. Furthermore, a simultaneous increase in the piston length and piston diameter was more effective for reducing the axial-thrust imbalance along with the volumetric efficiency drop.