• Title/Summary/Keyword: Hot environment

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Corrosion Behavior of $Y_2O_3$ Coating in an Electrolytic Reduction Process (전해환원공정에서 $Y_2O_2$ 코팅층의 부식거동)

  • Cho, Soo-Haeng;Hong, Sun-Seok;Kang, Dae-Seung;Jeong, Myeong-Soo;Park, Byung-Heong;Hur, Jin-Mok;Lee, Han-Soo
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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    • v.8 no.1
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    • pp.33-39
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    • 2010
  • The electrolytic reduction of a spent oxide fuel involves a liberation of the oxygen in a molten LiCl electrolyte, which results in a chemically aggressive environment that is too corrosive for typical structural materials. Accordingly, it is essential to choose the optimum material for the processing equipment that handles the high molten salt. In this study, hot corrosion studies were performed on bare as well as coated superalloy specimens after exposure to lithium molten salt at $675^{\circ}C$ for 216 h under an oxidizing atmosphere. The IN713LC superalloy specimens were sprayed with an aluminized NiCrAlY bond coat and then with an $Y_2O_3$ top coat. The bare superalloy reveals an obvious weight loss due to spalling of the scale by the rapid scale growth and thermal stress. The chemical and thermal stability of the top coat has been found to be beneficial for increasing to the corrosion resistance of the structural materials for handling high temperature lithium molten salts.

Distribution and Migration Characteristics of Explosive Compounds in Soil at Military Shooting Ranges in Gyeonggi Province (경기도 북부지역 군용 사격장 토양에 존재하는 화약물질 분포 및 이동 특성 조사)

  • Bae, Bumhan;Park, Jieun
    • Journal of the Korean GEO-environmental Society
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    • v.15 no.6
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    • pp.17-29
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    • 2014
  • A remedial investigation was conducted at five military training ranges in northern Gyeonggi province to collect information necessary for the design of on-site treatment facilities for the abatement of explosive compounds release to the environment. These information includes (i) identification of dominant explosive compounds in each range, (ii) discharge/migration routes, and (iii) contaminant distribution in particle size fraction and settling velocity of the soils. The results of investigation showed that TNT and RDX are the major contaminants but the extent of contamination varied depending on the types of military training practices and topography of the site. RDX was also detected in the subsurface soil and in the nearby stream within the training ranges, suggesting release of contaminants to streams. The median concentrations of explosives in the surface soil were less than 20 mg/kg despite several 'hot spots' in which explosives concentrations often exceeds several hundred mg/kg. The average clay contents in the soil of target area was less than 5 % compared to 12 % in the control, indicating loss of smaller particles by surface runoff during rainfall due to lack of vegetative land cover. Analysis of explosive compounds and particle size distribution showed that the amount of explosive compounds in soil particles smaller than 0.075 mm was less than 10 % of the total. Settling column tests also revealed that the quantity of explosive compounds in the liquid phase of the effluent was greater than that in the solid phase. Therefore, pre-treatment of particulate matter in surface runoff of shooting range with a simple settling basin and subsequent effluent treatment with planted constructed wetlands as polishing stage for explosives in the aqueous phase would provide the shooting ranges with a self-standing, sustainable, green solution.

Nematicidal Efficacy of Herbal Extracts against Meloidogyne hapla (당근뿌리혹선충에 대한 식물추출물의 살선충 효과)

  • Lee, Jung-Su;Choo, Ho-Yul;Lee, Dong-Woon
    • Korean journal of applied entomology
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    • v.50 no.4
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    • pp.315-324
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    • 2011
  • The nematicidal and egg haching inhibitory effects of extracts from 30 herbal plants (total 32 samples) against Meloidogyne hapla J2 juveniles and eggs was tested using the dipping method. At 1,000 ppm, extracts of Daphne genkwa flower buds, Eugenia caryophyllata flowers, Quisqualis indica fruits, and Zingiber officinale rhizomes produced > 80% mortality in J2 juveniles. At 125 ppm, extracts of D. genkwa and Q. indica produced 91 and 99% mortality, respectively. The toxicity of 5 selected plant extracts to M. hapla differed depending on the solvent used (i.e. hexane, methanol, hot water, or cold water). Hot water extracts of Z. officinale and Q. indica produced nematicidal efficacies of 99 and 99%, compared to 36 and 98%, respectively, with cold water extraction. Q. indica extract was highly active against M. hapla regardless of extraction method. The inhibitory effects of Areca catechu, D. genkwa, Desmodium caudatum, Pharbitis nil, Q. indica, and Z. officinale extracts on egg hatching of M. hapla was evaluated. At 1,000 ppm, D. genkwa, P. nil, and Q. indica extracts significantly reduced hatching at 7, 14 and 21 days after treatment. Numbers of juveniles in soil treated with the methanol extract D. genkwa (1,000 ppm) were significantly lower than in untreated soil in trials in pots and in a ginseng (Phanax ginseng) field. These results indicate that Q. indica extracts could be used as an environmental friendly control agent of M. hapla.

Variation of Hydrogen Residue on Metallic Samples by Thermal Soaking in an Inert Gas Environment (불활성 가스하 열건조에 따른 금속시험편의 수소잔류물 거동 분석)

  • Lee, Yunhee;Park, Jongseo;Baek, Unbong;Nahm, Seunghoon
    • Journal of Hydrogen and New Energy
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    • v.24 no.1
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    • pp.44-49
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    • 2013
  • Hydrogen penetration into a metal leads to damages and mechanical degradations and its content measurement is of importance. For a precise measurement, a sample preparation procedure must be optimized through a series of studies on sample washing and drying. In this study, two-step washing with organic solvents and thermal soaking in inert gas were tried with a rod-shaped, API X65 steel sample. The samples were machined from a steel plate and then washed in acetone and etyl-alcohol for 5 minute each and dried with compressed air. After then, the samples were thermally soaked in a home-made nitrogen gas chamber during 10 minute at different heat gun temperatures from 100 to $400^{\circ}C$ and corresponding temperature range in the soaking chamber was from 77 to $266^{\circ}C$ according to the temperature calibration. Hydrogen residue in the samples was measured with a hot extraction system after each soaking step; hydrogen residue of $0.70{\pm}0.12$ wppm after the thermal soaking at $77^{\circ}C$ decayed with increase of the soaking temperature. By adopting the heat transfer model, decay behavior of the hydrogen residue was fitted into an exponential decay function of the soaking temperature. Saturated value or lower bound of the hydrogen residue was 0.36 wppm and chamber temperature required to lower the hydrogen residue about 95% of the lower bound was $360^{\circ}C$. Furthermore, a thermal desorption spectroscopy was done for the fully soaked samples at $360^{\circ}C$. Weak hydrogen peak was observed for whole temperature range and it means that hydrogen-related contaminants of the sample surface are steadily removed by heating. In addition, a broad peak found around $400^{\circ}C$ means that parts of the hydrogen residue are irreversibly trapped in the steel microstructure.

Genetic Analysis of Days to Flowering in Korean Hot Pepper (한국 건고추 개화소요일수의 유전 분석)

  • Soh, Jae-Woo;Lee, Yong-Beom;Nam, Sang-Yong
    • Horticultural Science & Technology
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    • v.31 no.1
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    • pp.89-94
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    • 2013
  • This study was carried out to calculate the genic values of days for flowering in commercial breeding lines of Korean hot pepper (Capsicum annuum L.). Two breeding lines of pepper '#2132' ($P_1$) early-flowering, and '#1308' ($P_2$) medium-late flowering, and their $F_1$ and $F_2$ generations were used in this study. By using partitioning method (Thseng and Hosokawa, 1971, 1972), it was possible to estimate, from the $F_2$ generations, the number of effective factor pairs differentiating the two parents. It was found out that the two parents were differentiated by two effective factor pairs, A:a and B:b. In the breeding lines used, the inheritance of days to flowering showed that the $F_1$ flowered a little earlier than the earlier flowering parent through the effect of over-dominance. However, $F_2$ flowered earlier or later than both parents through transgressive segregation. Conclusively, the magnitude of genic effects of A-a gene in flowering days was -13.81 days, and B-b gene was -6.73 days. The interaction between the two non-allelic factors using partitioning method was -5.26 days.

Recent Progress in Air-Conditioning and Refrigeration Research : A Review of Papers Published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2016 (설비공학 분야의 최근 연구 동향 : 2016년 학회지 논문에 대한 종합적 고찰)

  • Lee, Dae-Young;Kim, Sa Ryang;Kim, Hyun-Jung;Kim, Dong-Seon;Park, Jun-Seok;Ihm, Pyeong Chan
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.29 no.6
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    • pp.327-340
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    • 2017
  • This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2016. It is intended to understand the status of current research in the areas of heating, cooling, ventilation, sanitation, and indoor environments of buildings and plant facilities. Conclusions are as follows. (1) The research works on the thermal and fluid engineering have been reviewed as groups of flow, heat and mass transfer, the reduction of pollutant exhaust gas, cooling and heating, the renewable energy system and the flow around buildings. CFD schemes were used more for all research areas. (2) Research works on heat transfer area have been reviewed in the categories of heat transfer characteristics, pool boiling and condensing heat transfer and industrial heat exchangers. Researches on heat transfer characteristics included the results of the long-term performance variation of the plate-type enthalpy exchange element made of paper, design optimization of an extruded-type cooling structure for reducing the weight of LED street lights, and hot plate welding of thermoplastic elastomer packing. In the area of pool boiling and condensing, the heat transfer characteristics of a finned-tube heat exchanger in a PCM (phase change material) thermal energy storage system, influence of flow boiling heat transfer on fouling phenomenon in nanofluids, and PCM at the simultaneous charging and discharging condition were studied. In the area of industrial heat exchangers, one-dimensional flow network model and porous-media model, and R245fa in a plate-shell heat exchanger were studied. (3) Various studies were published in the categories of refrigeration cycle, alternative refrigeration/energy system, system control. In the refrigeration cycle category, subjects include mobile cold storage heat exchanger, compressor reliability, indirect refrigeration system with $CO_2$ as secondary fluid, heat pump for fuel-cell vehicle, heat recovery from hybrid drier and heat exchangers with two-port and flat tubes. In the alternative refrigeration/energy system category, subjects include membrane module for dehumidification refrigeration, desiccant-assisted low-temperature drying, regenerative evaporative cooler and ejector-assisted multi-stage evaporation. In the system control category, subjects include multi-refrigeration system control, emergency cooling of data center and variable-speed compressor control. (4) In building mechanical system research fields, fifteenth studies were reported for achieving effective design of the mechanical systems, and also for maximizing the energy efficiency of buildings. The topics of the studies included energy performance, HVAC system, ventilation, renewable energies, etc. Proposed designs, performance tests using numerical methods and experiments provide useful information and key data which could be help for improving the energy efficiency of the buildings. (5) The field of architectural environment was mostly focused on indoor environment and building energy. The main researches of indoor environment were related to the analyses of indoor thermal environments controlled by portable cooler, the effects of outdoor wind pressure in airflow at high-rise buildings, window air tightness related to the filling piece shapes, stack effect in core type's office building and the development of a movable drawer-type light shelf with adjustable depth of the reflector. The subjects of building energy were worked on the energy consumption analysis in office building, the prediction of exit air temperature of horizontal geothermal heat exchanger, LS-SVM based modeling of hot water supply load for district heating system, the energy saving effect of ERV system using night purge control method and the effect of strengthened insulation level to the building heating and cooling load.

Effect of Root Zone Warming by Hot Water on Rhizosphere Environment and Growth of Greenhouse- grown Oriental Melon (Cucumis melo L.) (온수 지중가온이 참외의 근권환경 및 생육에 미치는 영향)

  • 신용습;이우승;도한우;배수곤;최성국
    • Journal of Bio-Environment Control
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    • v.6 no.2
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    • pp.103-109
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    • 1997
  • This experiment was conducted to investigate the effects of root zone warming on rhizosphere temperature of Oriental melon (Cucumis melo L. var. Makuwa) in winter season. Root zone was warmed by hot water flowing through pipe set at 35cm depth from the ridge. Treatments of minimum soil temperature at 20cm depth were 17, 21, $25^{\circ}C$, and non-warmed from Jan. 18 to Apr. 18. The results are summarized as follows. 1. The cumulative soil temperature for 1 month after planting oriental melon was 441, 558, 648, and 735$^{\circ}C$ at control, 17, 21, and $25^{\circ}C$ plot, respectively. 2. As soil temperature was higher, air temperature in tunnel was higher. The lowest temperature in control plot at night was 9.5$^{\circ}C$, 11.$0^{\circ}C$ in 17$^{\circ}C$ plot, 13.5$^{\circ}C$ in 21$^{\circ}C$ plot, and 16.5$^{\circ}C$ in $25^{\circ}C$ plot, respectively. 3. The xylem exudate amount of control plot for 24 hours just after basal stem abscission was 8.1$m\ell$. It was 1.2 times higher in 17$^{\circ}C$ plot, 1.3 times higher in 21 $^{\circ}C$ plot, and 4.8 times higher in $25^{\circ}C$ plot than in control plot at 30 days after planting. The xylem exudate amount at 67 days after planting of control plot was 10.4$m\ell$, those of 17, 21, $25^{\circ}C$ plots were 1.1, 3.2, and 3.3 times as compared to control plot. 4, Early growth in leaf length, stem diameter, leaf number and leaf area for 30 days after planting were better in higher temperature plots than in control plot. Particularly, the increase of leaf area was striking in higher temperature plots. Leaf area of control plot was 279.5$\textrm{cm}^2$ for 30 days after planting, 153.4% in 17$^{\circ}C$ plot, 745.6% in 21$^{\circ}C$ plot and 879.4% in $25^{\circ}C$ plot were increased as compared to in control plot.

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Deformation Characteristics of Zircaloy-4 Fuel Cladding due to Oxidation in Environment of High Temperature and Steam (고온, 수증기 속에서 산화된 질칼로이-4 핵연료 피복관의 변형 특성에 관한 연구)

  • Jung, Sung-Hoon;Suh, Kyung-Soo;Kim, In-Sup
    • Nuclear Engineering and Technology
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    • v.18 no.3
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    • pp.218-227
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    • 1986
  • Studies were conducted to determine the extent of oxidation and same of the mechanical property changes of Zircaloy-4 fuel cladding after it was exposed to hot steam environment. The purpose of these tests was to provide some informations on the embrittlement behavior of CANDU type fuel cladding, which could be experienced under the loss-of-coolant accident conditions. The Zircaloy fuel cladding tubes were exposed in a steam environment at the temperature of 90$0^{\circ}C$, 1,00$0^{\circ}C$. The growth of the ZrO$_2$ layer combined with an oxygen rich $\alpha$-phase layer into the Zircaloy tube material was found as a function of time t and temperature of steam exposure, E=1.1√Dt+0.002 where D is a temperature dependent diffusion coefficient. The tensile strength of the specimens exposed for a short period increased but decreased continuously with further exposure. The circumferential elongation was drastically changed with the exposure time while the hoop strength did't decrease greatly. The X-ray measurement of preferred orientation of the Zircaloy tube material indicated that grains in the as received tube were oriented such that the poles of the basal (0001) planes were predominantly radial, while the poles of the basal plane in the tube materials heattreated at 1,00$0^{\circ}C$ were oriented tangentially. It appears that this reoriented texture may contribute to lessening the decrease of the hoop strength of the heat treated Zircaloy tube material.

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Analyzing the impact of increase in energy price on the general price level (에너지원별 가격조정의 물가파급효과 분석)

  • Lim, Seul-Ye;Song, Tae-Ho;Yoo, Seung-Hoon
    • Journal of Energy Engineering
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    • v.22 no.4
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    • pp.376-385
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    • 2013
  • There are conflicts about energy price increase among government, producer, and consumer. The supplier insists on price increase for escaping running a deficit and business continuity, but the consumer concerns about worsening profitability and price rise. This study investigates the effects of energy rate increase on national economy using input-ouput(I-O) analysis. This study attempts to analyze the effects of national economy due to Coke and hard-coal, Naphtha, Gasoline, Kerosene, Light oil, Heavy oil, Liquefied petroleum gas, Electric utilities, Manufactured gas supply and Steam and hot water supply (using input-output table for the year 2011, Korea.) The results of the sectoral price changes due to a 10% increase in energy price that is obtained from the Leontief price model are presented in article. The result of this analysis is presented: The impact of the 10% increase in electricity rate on the general price level is estimated to be 0.2196%. In case of Kerosene, the impact is 0.1222%. It shows that Electric utilities are approximately 18 times larger price inducing effect as Kerosene. Also, this study indicates 3 years results sequentially to make it possible to observe trend. Then, study suggests balancing price by making each energy source adjusted.

Spatial Analysis of the Difference between Real Crime and Fear of Crime (도시내 범죄발생과 범죄 두려움 위치의 공간적 차이 분석)

  • Heo, Sun-Young;Moon, Tae-Heon
    • Journal of the Korean Association of Geographic Information Studies
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    • v.14 no.4
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    • pp.194-207
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    • 2011
  • This study tries to find the possibility to prevent crime by improving urban spatial environment through the analysis of spatial environment property that mutually coincides or differs by comparing the place where crime actually occurs and the place where citizen is afraid of crime. The method of study is as follows. First, the ontents scope and method of study was established by theoretic investigation of case study related to crime. Second, as crime cannot be prevented by police power only, CPSCP(Citizen Participation System for Crime Prevention) was developed so that all citizen can cooperatively participate in the crime prevention anytime and anywhere. Third, the data on the place where people feel fear in the region was collected by directly indicating the place where citizen is afraid of crime in the space by utilizing CPSCP. Fourth, the place where crime actually occurs and the place where citizen is afraid of crime are redundantly analyzed for comparative analysis of 2 places. The result shows that environmental design improving physical environment of urban space is necessary to prevent crime and to eliminate the fear of crime. The CPSCP developed by this study which will be advanced to U-crime prevention system will contribute to making citizen's own neighborhood a smart safety city autonomously.