• Title/Summary/Keyword: Field release

Search Result 477, Processing Time 0.027 seconds

Dispersion Model of Initial Consequence Analysis for Instantaneous Chemical Release (순간적인 화학물질 누출에 따른 초기 피해영향 범위 산정을 위한 분산모델 연구)

  • Son, Tai Eun;Lee, Eui Ju
    • Journal of the Korean Society of Safety
    • /
    • v.37 no.2
    • /
    • pp.1-9
    • /
    • 2022
  • Most factories deal with toxic or flammable chemicals in their industrial processes. These hazardous substances pose a risk of leakage due to accidents, such as fire and explosion. In the event of chemical release, massive casualties and property damage can result; hence, quantitative risk prediction and assessment are necessary. Several methods are available for evaluating chemical dispersion in the atmosphere, and most analyses are considered neutral in dispersion models and under far-field wind condition. The foregoing assumption renders a model valid only after a considerable time has elapsed from the moment chemicals are released or dispersed from a source. Hence, an initial dispersion model is required to assess risk quantitatively and predict the extent of damage because the most dangerous locations are those near a leak source. In this study, the dispersion model for initial consequence analysis was developed with three-dimensional unsteady advective diffusion equation. In this expression, instantaneous leakage is assumed as a puff, and wind velocity is considered as a coordinate transform in the solution. To minimize the buoyant force, ethane is used as leaked fuel, and two different diffusion coefficients are introduced. The calculated concentration field with a molecular diffusion coefficient shows a moving circular iso-line in the horizontal plane. The maximum concentration decreases as time progresses and distance increases. In the case of using a coefficient for turbulent diffusion, the dispersion along the wind velocity direction is enhanced, and an elliptic iso-contour line is found. The result yielded by a widely used commercial program, ALOHA, was compared with the end point of the lower explosion limit. In the future, we plan to build a more accurate and general initial risk assessment model by considering the turbulence diffusion and buoyancy effect on dispersion.

Numerical Study of Thermal Choking Process in a Model SCRamjet Combustor (모델 스크램제트 연소기 내의 열적 질식 과정 수치 연구)

  • Lee, B.R.;Moon, G.W.;Jeung, I.S.;Choi, J.Y.
    • 한국연소학회:학술대회논문집
    • /
    • 2000.12a
    • /
    • pp.83-91
    • /
    • 2000
  • A numerical study was carried out to investigate the 'unstart' process of thermally-choked combustion in model scramjet engines. The combustion mechanism of supersonic combustor will be compared with the experimental results obtained from the T3 free-piston shock tunnel at ANU (Australian National University) and the high enthalpy supersonic wind tunnel at UT (University of Tokyo). For the numerical simulation of supersonic combustion. multi-species Navier-Stokes equations were considered. and detailed chemistry reaction mechanism of $H_2$-Air were adopted. The governing equations were solved by Roe's FDS method and LU-SGS method with MUSCL scheme. In this study. it is found that the thermal choking process could result from excessive heat release due to combustion. In detail, sufficient heat release could be generated at local region of very high temperature increased by reflection of shock waves or vortex sheets. Accordingly the flow of downstream of the combustor fell to subsonic field propagated upstream along the combustor. Sometimes the subsonic flow field propagated into isolator could generate precombustion shock waves in the isolator.

  • PDF

Calibration and Sensitivity Analysis of the RICEWQ Model (RICEWQ 모형의 보정 및 민감도 분석)

  • Chung, Sang-Ok;Park, Ki-Jung;Son, Seung-Ho
    • Journal of The Korean Society of Agricultural Engineers
    • /
    • v.50 no.2
    • /
    • pp.3-10
    • /
    • 2008
  • The main objectives of this study are to calibrate the RICEWQ model with Korean field data and then analyse the sensitivity of the parameters to identify sensitive parameters. The RICEWQ is widely used to predict pesticide fate in a paddy plot. An experimental paddy plot of 0.2 ha($100{\times}20\;m$) at Seobyeon-dong, Daegu, Korea was selected, and field observations for water and pesticide balance were performed from 4 June to 2 September 2006. The molinate, which is a herbicide widely used for weed control in rice culture, was selected. The RICEWQ model was successfully calibrated both for the water and pesticide mass balance. The calibrated model showed a RMSE of 0.537 cm for ponded water depths and a RMSE of 0.036 mg/L for the molinate concentrations in the ponded water. The most sensitive parameters for molinate concentrations in ponded water were the metabolism degradation rate in water, volatilization coefficient, and release rate for slow release formulation. In contrast, the RICEWQ model was not sensitive to parameters such as hydrolysis degradation rate in water and degradation rate in unsaturated soil.

Co-inoculation of Burkholderia cepacia and Alcaligenes aquatilis enhances plant growth of maize (Zea mays) under green house and field condition

  • Pande, Amit;Pandey, Prashant;Kaushik, Suresh
    • Korean Journal of Agricultural Science
    • /
    • v.44 no.2
    • /
    • pp.196-210
    • /
    • 2017
  • The synergistic effect on phosphate solubilization of single- and co-inoculation of two phosphate solubilizing bacteria, Burkholderia cepacia (C1) and Alcaligenes aquatilis (H6), was assessed in liquid medium and maize plants. Co-inoculation of two strains was found to release the highest content of soluble phosphorus (309.66 ?g/mL) into the medium, followed by single inoculation of B. cepacia (305.49 ?g/mL) and A. aquatilis strain (282.38 ?g/mL). Based on a plant growth promotion bioassay, co-inoculated maize seedlings showed significant increases in shoot height (75%), shoot fresh weight (93.10%), shoot dry weight (84.99%), root maximum length (55.95%), root fresh weight (66.66%), root dry weight (275%), and maximum leaf length (81.53%), compared to the uninoculated control. In a field experiment, co-inoculated maize seedlings showed significant increases in cob length (136.92%), number of grain/cob (46.68%), and grain weight (67.46%) over control. In addition, single inoculation of maize seedlings also showed improved result over control. However, there was no significant difference between single inoculation of either bacterial strains and co-inoculation of these two bacterial strains in terms of phosphate solubilization index, phosphorous release, pH of the media, and plant growth parameters. Thus, single inoculation and co-inoculation of these bacteria could be used as biofertilizer for improving maize growth and yield.

Tracing the origin of fish without hatchery information: genetic management of stock enhancement for mangrove red snapper (Lutjanus argentimaculatus) in Taiwan

  • Hsu, Te-Hua;Huang, Chang-Wen;Lin, Cheng-Hui;Lee, Hung-Tai;Pan, Chieh-Yu
    • Fisheries and Aquatic Sciences
    • /
    • v.23 no.5
    • /
    • pp.13.1-13.7
    • /
    • 2020
  • Stock enhancement is considered to be a valuable approach for restoring fishery resources. Because no specific official institution in Taiwan is responsible for the production of fry, the released fry are purchased directly from the private sector. However, fishermen from the private industry have not established a genetic background, so the genetic composition for each batch of released fry is unclear. Mangrove red snapper (Lutjanus argentimaculatus), a prominent species released in Taiwan, was collected after its official release. One hundred and two field samples were compared with four batches of hatchery fry (n = 685) by using a microsatellite-based multiplex PCR assay. Four of the field samples (3.9%; 4/102) were revealed to be from a fish farm and most likely from a single batch. This study revealed that wild mangrove red snappers are genetically different from those originating from farms, and their origins can be traced through molecular markers, even without information on breeding stocks.

Analysis of Propagating Crack Along Interface of Isotropic-Orthotropic Bimaterial by Photoelastic Experiment

  • Lee, K.H.;Shukla, A.;Parameswaran, V.;Chalivendra, V.;Hawong, J.S.
    • Proceedings of the KSME Conference
    • /
    • 2001.06a
    • /
    • pp.102-107
    • /
    • 2001
  • Interfacial cracks between an isotropic and orthotropic material, subjected to static far field tensile loading are analyzed using the technique of photoelasticity. The fracture parameters are extracted from the full-field isochromatic data and the same are compared with that obtained using boundary collocation method. Dynamic Photoelasticity combined with high-speed digital photography is employed for capturing the isochromatics in the case of propagating interfacial cracks. The normalized stress intensity factors for static crack is greater when $\alpha=90^{\circ}C$ (fibers perpendicular to the interface) than when $\alpha=0^{\circ}C$ (fiber parallel to the interface) and those when $\alpha=90^{\circ}C$ are similar to ones of isotropic material. The dynamic stress intensity factors for interfacial propagating crack are greater when $\alpha=0^{\circ}C$ than $\alpha=90^{\circ}C$. The relationship between complex dynamic stress intensity factor $|K_D|$ and crack speed C is similar to that for isotropic homogeneous materials, the rate of increase of energy release rate G or $|K_D|$ with crack speed is not as drastic as that reported for homogeneous materials.

  • PDF

Numerical Modelling of Radionuclide Migration for the Underground Silo at Near-Field

  • Myunggoo Kang;Jaechul Ha
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
    • /
    • v.21 no.4
    • /
    • pp.465-479
    • /
    • 2023
  • To ensure the safety of disposal facilities for radioactive waste, it is essential to quantitatively evaluate the performance of the waste disposal facilities by using safety assessment models. This paper addresses the development of the safety assessment model for the underground silo of Wolseong Low-and Immediate-Level Waste (LILW) disposal facility in Korea. As the simulated result, the nuclides diffused from the waste were kept inside the silo without the leakage of those while the integrity of the concrete is maintained. After the degradation of concrete, radionuclides migrate in the same direction as the groundwater flow by mainly advection mechanism. The release of radionuclides has a positive linear relationship with a half-life in the range of medium half-life. Additionally, the solidified waste form delays and reduces the migration of radionuclides through the interaction between the nuclides and the solidified medium. Herein, the phenomenon of this delay was implemented with the mass transfer coefficient of the flux node at numerical modeling. The solidification effects, which are delaying and reducing the leakage of nuclides, were maintained the integrity of the nuclides. This effect was decreased by increasing the half-life and the mass transfer coefficient of radionuclides.

Effect of Slow-Release Fertilizer on Yield and Quality of Third-Harvest Tea Leaves (세물차의 수량 및 품질에 미치는 완효성비료 시비효과)

  • Park, Jang-Hyun;Choi, Hyeong-Kuk;Kim, Jong-Keun;Kim, Kil-Yong
    • Korean Journal of Soil Science and Fertilizer
    • /
    • v.38 no.5
    • /
    • pp.269-273
    • /
    • 2005
  • A field experiment was conducted to evaluate the effect of slow-release fertilizer on the yield and quality of the third-harvest tea leaves. The yield of the third harvested tea leaves was decreased to 5.8-14.4% in slow-release fertilizer block, except to the N $50kg\;10a^{-1}$ ($316kg\;10a^{-1}$), compared to traditional urea treatment ($313kg\;10a^{-1}$). Nitrogen uptake and nitrogen uptake efficiency of slow-release fertilizer was reduced as nitrogen application level increased. The contents of chemical components related to the tea quality such as total-nitrogen, total amino acid, chlorophyll and theanine were somewhat lower in the slow-release fertilizer treatments, except to the treatment of N $50kg\;10a^{-1}$, than those in the traditional urea application, but those of tannin, caffeine and vitamin C were not different among the treatments. In scoring test, apparence and quality of green tea of the slow-release fertility treatments were not different, except to the N $40kg\;10a^{-1}$ treatment, compared to those in the treatment of urea. In conclusion, slow-release fertilizer and conventional urea treatments showed not different in both yield and quality of green tea.

Performance analysis of a 746 W HTS generator equipped with 70 A class contactless superconducting field exciter

  • Chae, Yoon Seok;Kim, Ho Min
    • Progress in Superconductivity and Cryogenics
    • /
    • v.22 no.3
    • /
    • pp.1-6
    • /
    • 2020
  • This paper presents the analysis results on the electrical output performance characteristics of a 746 W high temperature superconducting generator (HTSG). The HTS field winding is charged by non-contact excitation method, i.e., contactless superconducting field exciter (CSFE) which is originated by rotary flux pump based on permanent magnet. In this paper, the preliminary current charging test was carried out using a 70 A CSFE to evaluate the performance of field exciter and analyze its non-contact excitation characteristics for the full-scale HTS field winding of the 746 W HTSG. First, the various contactless current-charging tests were conducted using assembly with HTS field winding and CSFE. Then, in order to estimate the output power performance characteristics of the 746 W HTSG, finite element analysis was conducted based on field excitation information which is experimentally measured under various operating conditions. Finally, the electrical output characteristics in no-load and load models were simulated by two-dimensional transient solver in ANSYS electromagnetics 19.0 release.

THE AKARI DEEP FIELD SOUTH: PUSHING TO HIGH REDSHIFT

  • Clements, David L.
    • Publications of The Korean Astronomical Society
    • /
    • v.32 no.1
    • /
    • pp.275-279
    • /
    • 2017
  • The AKARI Deep Field South (ADF-S) is a large extragalactic survey field that is covered by multiple instruments, from optical to far-IR and radio. I summarise recent results in this and related fields prompted by the release of the Herschel far-IR/submm images, including studies of cold dust in nearby galaxies, the identification of strongly lensed distant galaxies, and the use of colour selection to find candidate very high redshift sources. I conclude that the potential for significant new results from the ADF-S is very great. The addition of new wavelength bands in the future, eg. from Euclid, SKA, ALMA and elsewhere, will boost the importance of this field still further.