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Sulfide Chimney from the Cleft Segment, Juan de Fuca Ridge: Mineralogy and Fluid Inclusion (Juan de Fuca 해령 Cleft Segment에서 회수된 황화물 침니: 광물조성 및 유체포유물)

  • 윤성택;허철호;소칠섭;염승준;이경용
    • Economic and Environmental Geology
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    • v.35 no.3
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    • pp.203-210
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    • 2002
  • In order to elucidate the growth mechanism of sulfide chimney formed as a result of seafloor hydrothermal mineralization, we carried out the mineralogical and fluid inclusion studies on the inactive, sulfide- and silica-rich chimney which has been recovered from a hydrothermal field in the Cleft segment of the Juan de Fuca Ridge. According to previous studies, many active and inactive vents are present in the Cleft segment. The sulfide- and silica-rich chimney is composed of amorphous silica, pyrite, sphalerite and wurtzite with minor amounts of chalcopyrite and marcasite. The interior part of the chimney is highly porous and represents a flow channel. Open spaces within chimneys are typically coated with colloform layers of amorphous silica. The FeS content of Zn-sulfides varies widely from 13.9 to 34.3 mole% with Fe-rich core and Fe-poor rims. This variation possibly reflects the change of physicochemical characteristics of hydrothermal fluids. Chemical and mineralogical compositions of the each growth zone are also varied, possibly due to a thermal gradient. Based on the microthermometric measurements of liquid-rich, two-phase inclusions in amorphous silica that was precipitated in the late stage of mineralization, minimum trapping temperatures are estimated to be about 1140 to 145$^{\circ}$C with the salinities between 3.2 and 4.8 wt.% NaCI equiv. Although the actual fluid temperatures of the vent are not available, this study suggests that the lowtemperature conditions were predominant during the mineralization in the hydrothermal field at Cleft segment. Comparing with the previously reported chimney types, the morphology, colloform texture, bulk chemistry, and a characteristic mineral assemblage (pyrite + marcasite + wurtzite + amorphous silica) of this chimney indicate that the chimney have been formed from a relatively low-temperature (<250$^{\circ}$C) hydrothermal fluid that was changed by sluggish fluid flow and conductive cooling.

Effects of blast-induced random ground motions on the stochastic behaviour of industrial masonry chimneys

  • Haciefendioglu, Kemal;Soyluk, Kurtulus
    • Structural Engineering and Mechanics
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    • v.43 no.6
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    • pp.835-845
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    • 2012
  • This paper focuses on the stochastic response analysis of industrial masonry chimneys to surface blast-induced random ground motions by using a three dimensional finite element model. Underground blasts induce ground shocks on nearby structures. Depending on the distance between the explosion centre and the structure, masonry structures will be subjected to ground motions due to the surface explosions. Blast-induced random ground motions can be defined in terms of the power spectral density function and applied to each support point of the 3D finite element model of the industrial masonry system. In this paper, mainly a parametric study is conducted to estimate the effect of the blast-induced ground motions on the stochastic response of a chimney type masonry structure. With this purpose, different values of charge weight and distance from the charge centre are considered for the analyses of the chimney. The results of the study underline the remarkable effect of the surface blast-induced ground motions on the stochastic behaviour of industrial masonry type chimneys.

Fluid Flow and Heat Transfer Inside a Solar Chimney Power Plant

  • Gholamalizadeh, Ehsan;Chung, Jae Dong
    • Plant Journal
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    • v.14 no.1
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    • pp.42-46
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    • 2018
  • The flow and heat transfer characteristics inside a solar chimney power plant system are analyzed in this article. 3-D model with the $k-{\varepsilon}$ turbulence closure was developed. In this model, to solve the radiative transfer equation the discrete ordinates radiation model was implemented, using a two-band radiation model. To simulate radiation effects from the sun's rays, the solar ray tracing algorithm was coupled to the calculation via a source term in the energy equation. Simulations were carried out for a system with the geometry parameters of the Manzanares power plant. Based on the numerical results, the velocity and temperature distributions were illustrated and the results were validated by comparing with experimental data of the Manzanares prototype power plant. Moreover, temperature profile of the ground surface of the system was illustrated.

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Study on the Natural Convection Heat-Transfer Enhancement in Radial Heat Sink Using the Perforation and Flow Guide (천공과 유동 가이드를 활용한 방사형 히트싱크의 자연대류 열전달 향상에 관한 연구)

  • Jeon, Sora;Li, Bin;Byon, Chan
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.40 no.5
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    • pp.339-345
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    • 2016
  • In this study, we numerically investigate the thermal performance of an enhanced radial heat sink with a perforation and chimney structure. We estimate the thermal performance of the enhanced radial heat sink, and compared it with that of a conventional radial heat sink. The results show that the radial heat sink with perforation has a higher thermal performance when either of the diameter and the number of perforations is high. With regards to the radial heat sink with a chimney structure, we investigate primarily the effect of the fin number, and the spacing between the chimney and the base plate on the thermal performance. The results show that there are optimal values for the fin number and the spacing between chimney and base plate. In addition, the enhanced radial heat sinks have maximum thermal performance when facing upward ($0^{\circ}$), while it has worst performance when facing sideward ($90^{\circ}$). The perforation and chimney are shown to cause thermal performance enhancements of 17% and 20%, respectively, compared with a conventional radial heat sink. The proposed method is useful for starting business, and is useful in terms of venture and entrepreneurship.

저온기 육용계사의 적정 환기체계 구명

  • 이덕수;나재천;최희철;송준익;이상진;김형호
    • Proceedings of the Korea Society of Poultry Science Conference
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    • pp.108-109
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    • 2002
  • The study was carried out to iind out the suitable ventilation system of the broiler house in winter season in Korea. Ammonia (NH$_3$-N) gas concentration (4.2ppm) of the system of pipe air inlet-forced chimney outlet was lower than that of the system of side wall inlet. The growth performance of broilers in the house equiped with pipe air inlet-chimney exhaust was higher than that of other ventilation systmes in which the average daily gain, feed efficiency and heat cost per head in the system of pipe air inlet-forced chimney excretion were 45.6g, 1.71 and 35.4 won per head, respectively. When the lengths of pipe air inlets were compared, the wind speed from the 4 meter-inlet was highest. The temperature of the broiler house equipped with the pipe air inlet system was higher (5.9 ∼ 7.7$^{\circ}C$) than that of the curtains in side wall Inlet system, in which the pipe air inlet system expects the lower heat cost.

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Port-Site Metastases and Chimney Effect of B-Ultrasound-Guided and Laparoscopically-Assisted Hyperthermic Intraperitoneal Perfusion Chemotherapy

  • Ba, Ming-Chen;Long, Hui;Zhang, Xiang-Liang;Gong, Yuan-Feng;Yan, Zhao-Fei;Wang, Shuai;Tang, Yun-Qiang;Cui, Shu-Zhong
    • Yonsei Medical Journal
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    • v.58 no.3
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    • pp.497-504
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    • 2017
  • Purpose: $CO_2$ leakage along the trocar (chimney effect) has been proposed to be an important factor underlying port-site metastasis after laparoscopic surgery. This study aimed to test this hypothesis by comparing the incidence of port-site metastasis between B-ultrasound-guided and laparoscopically-assisted hyperthermic intraperitoneal perfusion chemotherapy (HIPPC). Materials and Methods: Sixty-two patients with malignant ascites induced by gastrointestinal or ovarian cancer were divided into two groups to receive either B-ultrasound-guided or laparoscopically-assisted HIPPC. Clinical efficacy was assessed from the objective remission rate (ORR), the Karnofsky Performance Status (KPS) score, and overall survival. The incidence of port-site metastasis was compared between the two groups. Results: Patients in the B-ultrasound (n=32) and laparoscopy (n=30) groups were comparable in terms of age, sex, primary disease type, volume of ascites, and free cancer cell (FCC)-positive ascites. After HIPPC, there were no significant differences between the B-ultrasound and laparoscopy groups in the KPS score change, ORR, and median survival time. The incidence of port-site metastasis after HIPPC was not significantly different between the B-ultrasound (3 of 32, 9.36%) and laparoscopy (3 of 30, 10%) groups, but significantly different among pancreatic, gastric, ovarian, and colorectal cancer (33.33, 15.79, 10.00, and 0.00%, p<0.001). Conclusion: The chimney effect may not be the key reason for port-site metastasis after laparoscopy. Other factors may play a role, including the local microenvironment at the trocar site and the delivery of viable FCCs (from the tumor or malignant ascites) to the trauma site during laparoscopic surgery.

Electromagnetic Pulse (EMP) Shielding Effectiveness of Waveguide-Below-Cutoff (WBC) Arrays Installed in Generator Exhaust Chimney and its Effects on Gas Velocity (도파관 배열이 설치된 비상발전기 연도의 유속 예측 및 EMP 차폐평가)

  • Pang, Seung-Ki;Kim, Jae-Hun;Yook, Jong-Gwan;Kim, Yuna;Kim, Sangin;Kim, Suk-Bong
    • Transactions of the Korea Society of Geothermal Energy Engineers
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    • v.12 no.1
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    • pp.1-6
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    • 2016
  • Characteristics of exhaust from chimney of electricity generator are analyzed based on CFD when Waveguide-Below-Cutoff (WBC) array is installed in order to achieve the certain level of electromagnetic pulse (EMP) shielding. The main purpose is prediction of average and maximum velocity of exhaust. The results reveal that: 1) When the specification of waveguide is given as 80-diameter, 400-length, and the gap of 20 mm, the shielding effectiveness (SE) is 140dB. The average and maximum velocity of exhaust in the chimney with WBC Array can be represented as exponential functions. 2) As the number of WBC increases, the velocity in the chimney dwindles. 3) Under the situation that WBC with 80 mm diameter is located at intervals of 20 mm, the average velocity can be approximated by $25.5344{\times}e^{(-0.0098{\times}N_{WBC})}$ with input velocity of 15 m/s. In addition, the determination coefficient is 0.915, which is sufficiently high.

Application of the Solar Chimney System for Improving the Thermal Environment in Winter (겨울철 건물 열환경 개선을 위한 태양굴뚝 시스템의 응용)

  • Oh, Ju-Hong;Kim, Eui-Jong;Lee, Hyun-Soo;Suh, Seung-Jik
    • Journal of the Korean Solar Energy Society
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    • v.35 no.5
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    • pp.39-48
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    • 2015
  • In this study, the solar chimney, one of the passive solar systems, is proposed as a method to improve the thermal environment of northern zones in buildings. As this well-known system has rarely been used in building projects, an adequate application of the system is proposed in this paper: the solar chimney system is designed to meet the required ventilation rate and consequently to reduce the ventilation load in the northern part of a building. To investigate such a possibility, a numerical model for the system is developed, and results of numerical tests are used for energy simulations. The results were taken into account for test simulations in EnergyPlus. As a result, approximately 75% of the volumetric ventilation rate required in the north zone could be supplied with the air volume acquired through the system and the monthly mean load was reduced by 29.5%, from 1.584 kWh to 1.117 kWh. The analyses of hourly mean heating and ventilation load over the heating period indicated that the system was very effective at around 13:00. Results show that 33% reduction in the ventilation load and 17% in the heating load for the north zone could be acquired through this system.

A Design Optimization on Coupling Joint between Exhaust Chimney of Electricity Generator and Electromagnetic Pulse (EMP) Shield (EMP 차폐를 위한 비상발전기 연도의 최적 형상 결정)

  • Pang, Seung-Ki;Kim, Jae-Hun
    • Journal of Energy Engineering
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    • v.24 no.4
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    • pp.159-165
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    • 2015
  • The article presents a parametric study on geometrical design optimization for coupling the joint between a large exhaust air chimney and electromagnetic pulse (EMP) shield for gas turbine electricity generator. We conducted computational fluid dynamics (CFD) simulations on hydraulic diameters of waveguide below cutoff(WBC) ranges 800mm~1025mm, the connection distance ranges 150~450mm, and exhaust gas flow velocities at 15, 20, and 25m/s. The results show that the diameter of main chimney, connection distance, and exhaust gas velocity had impacts on flow stream at the EMP shield. To provide a fully developed stream line at three different flow velocity cases, the WBC diameter and distance of connection should be larger than 1050mm and longer than 300mm, respectively.

Response of fiber reinforced plastic chimneys to wind loads

  • Awad, A.S.;El Damatty, A.A.;Vickery, B.J.
    • Wind and Structures
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    • v.3 no.2
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    • pp.83-96
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    • 2000
  • Due to their high corrosion and chemical resistance, fiber reinforced plastics (FRP) are becoming widely used as the main structural material for industrial chimneys. However, no national code currently exists for the design of such type of chimneys. The purpose of this study is to investigate analytically the response of FRP chimneys to wind loads. The classical lamination theory is used to substitute the angle-ply laminate of a FRP chimney with an equivalent orthotropic material that provides the same stiffness. Dynamic wind loads are applied to the equivalent chimney to evaluate its response to both along and across wind loads. A parametric study is then conducted to identify the material and geometric parameters affecting the response of FRP chimneys to wind loads. Unlike the across-wind response, the along-wind tip deflection is found to be highly dependent on the angle of orientation of the fibers. In general, the analysis shows that FRP chimneys are very vulnerable to across-wind oscillations resulting from the vortex shedding phenomenon.