• Title/Summary/Keyword: Pool Temperature

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Changes in Non-Structural Carbohydrate in Overwintering Creeping Bentgrass (Agrostis palustris) (크리핑 벤트그라스의 월동중 비구조적 탄수화물의 변화)

  • Kim, Dae-Hyun;Jung, Woo-Jin;Lee, Bok-Rye;Kim, Kil-Yong;Kim, Tae-Hwan
    • Journal of The Korean Society of Grassland and Forage Science
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    • v.21 no.4
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    • pp.259-264
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    • 2001
  • To investigate the physiological responses to naturally occurring winter freezing stress in creeping bentgrass, changes in carbohydrates were monitored during winter period. Turf quality and leaf growth was nearly parallel with temperature fluctuation. The concentration of glucose, fructose and sucrose in both shoot and root gradually increased from November to January, and then sharply decreased until April. Sucrose was the largest pool of soluble sugars. Fructan also slightly accumulated in both shoot and roots from November to February. Fructan hydrolysis in both organs was found to be much active between February to April. Shoot contained largely higher carbohydrate content in all compounds examined than roots did. Fructan was found to be a main carbohydrate storage form, showing the highest concentration (176.7 and 126.7 mg g-' DW for shoot and root in February). The depolymerization of fructan from February coincided with the high declines in mono- and disaccharide. These results suggest that the accumulation of non-structural carbohydrate until January could be associated with freezing tolerance, and the active decrease from February with shoot regrowth.

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A coupled model simulation of the Last Glacial Maximum

  • Kim, Seong-Jung
    • Proceedings of the Korean Quaternary Association Conference
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    • 2004.11a
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    • pp.37-43
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    • 2004
  • The response of the CCCma coupled climate model to the imposition of LGM conditions is investigated. The global mean SAT and SST decrease by about $10^{\circ}C$ and $5.6^{\circ}C$ in the coupled model. Tropical SST decreases by $6.5^{\circ}C$, whereas CLIMAP reconstructions suggest that the tropics cool by only about $1.7^{\circ}C$, although the larger tropical cooling is consistent with the more recent proxy estimates. With the incorporation of a full ocean component, the coupled model gives a realistic spatial SST pattern, capturing features associated with ocean dynamics that are seen in the CLIMAP reconstructions. The larger decrease of the surface temperature in the model is associated with a reduction in global precipitation rate (about 15%). The tropical Pacific warm pool retreats to the west and a mean La $Ni\tilde{n}a$-like response is simulated with less precipitation over the central Pacific and more in the western tropical Pacific. The more arid ocean climate in the LGM results in an increase in SSS almost everywhere. This is particularly the case in the Arctic Ocean where large SSS increase is due to a decrease in river discharge to the Arctic Ocean associated with the accumulation of snow over the ice sheet, but in the North Atlantic by contrast SSS decreases markedly. This remarkable reduction of SSS in the North Atlantic is attributed to an increase in fresh water supply by an increase in discharges from the Mississippi and Amazon rivers and an increase in P-E over the North Atlantic ocean itself. The discharges increase in association with the wetter LGM climate south of the Laurentide ice sheet and in South America. The fresh water capping of the northern North Atlantic results in a marked reduction of deep convection and consequently a marked weakening of the North Atlantic overturning circulation. In the LGM, the maximum overturning stream function associated with the NADW formation decreases by about 60% relative to the control run, while in the Southern Ocean, oceanic convection is stronger in the LGM due to reduced stratification associated with an increase in SSS and a decrease in SST and the overturning stream function associated with the formation of AABW and the outflow increases substantially.

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Isolation of Defense-Related Genes from Nicotiana glutinosa Infected by Tobacco Mosaic Virus Using a Modified Differential Screening

  • Park, Kyung-Soon;Suh, Mi-Chung;Cheong, Jong-Joo;Park, Doil
    • The Plant Pathology Journal
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    • v.15 no.5
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    • pp.295-301
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    • 1999
  • Many of plant defense responses are consequence of transcriptional activation of related genes. We have developed a modified differential screening procedure to isolate tobacco genes that are involved in the defense responses against TMV infection. A cDNA library was constructed from Nicotiana glutinosa leaves infected by TMV under temperature shift conditions. Each of plasmid DNA in the library was hybridized on a set of slot blots to a pool of cDNA probes prepared from either TMV-infected or mock-treated tobacco leaves. Among 900 plasmid DNAs, 81 clones exhibiting significantly enhanced or reduced level of hybridization to either probe were selected for nucleotide sequencing. The clones were listed into 61 genes considering redundancy between the sequences. The genes were identified to be defense-related genes including PR-genes and genes involved in primary or secondary metabolisms. This results supports the implication that plant defense process entails a major shift in total cellular metabolisms rather than activation of a limited number of defense-related genes. Expression patterns of a number of defense-related genes. Expression patterns of a number of selected genes were examined in northern blot analyses. It is notable that the clone 630 of unknown function exhibits expression pattern similar to those of previously known PR-genes. Experiments to elucidate the roles in defense mechanism of a couple of genes newly identified in this study are in progress.

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Application of Water Mist System for a Power Transformer Room - Fire Extinguishment(Part 1) (변압기실 화재에 대한 미분무수 소화시스템의 적용 - 소화특성을 중심으로(Part 1))

  • Han Yong-Shik;Choi Byung-Il;Kim Myung-Bae
    • Fire Science and Engineering
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    • v.19 no.4 s.60
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    • pp.32-36
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    • 2005
  • A water mist system was considered as a possible alternative to a gaseous suppression system that can not prevent re-ignition after fire extinguishment for a power transformer room. This study deals with the fire suppression capability of the water mist systems. High-and low-pressure water mist systems were examined to compare efficiency of both systems. The power transformer examined in this study occupied about $7\%$ of a $10m\times10m\times$ transformer room. Full-scale suppression tests were performed for six different fire scenarios: two spray fires, three pool fires and one cascade fire. The fire suppression test results demonstrated that the high-pressure system was superior to the low-pressure system, especially considering oxygen depletion and the ambient temperature distribution.

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.

Recent Progress in Air-Conditioning and Refrigeration Research: A Review of Papers Published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2014 (설비공학 분야의 최근 연구 동향: 2014년 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.27 no.7
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    • pp.380-394
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    • 2015
  • This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2014. 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 heat and mass transfer, cooling and heating, and air-conditioning, the flow inside building rooms, and smoke control on fire. Research issues dealing with duct and pipe were reduced, but flows inside building rooms, and smoke controls were newly added in thermal and fluid engineering research area. (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 for thermal contact resistance measurement of metal interface, a fan coil with an oval-type heat exchanger, fouling characteristics of plate heat exchangers, effect of rib pitch in a two wall divergent channel, semi-empirical analysis in vertical mesoscale tubes, an integrated drying machine, microscale surface wrinkles, brazed plate heat exchangers, numerical analysis in printed circuit heat exchanger. In the area of pool boiling and condensing, non-uniform air flow, PCM applied thermal storage wall system, a new wavy cylindrical shape capsule, and HFC32/HFC152a mixtures on enhanced tubes, were actively studied. In the area of industrial heat exchangers, researches on solar water storage tank, effective design on the inserting part of refrigerator door gasket, impact of different boundary conditions in generating g-function, various construction of SCW type ground heat exchanger and a heat pump for closed cooling water heat recovery were performed. (3) In the field of refrigeration, various studies were carried out in the categories of refrigeration cycle, alternative refrigeration and modelling and controls including energy recoveries from industrial boilers and vehicles, improvement of dehumidification systems, novel defrost systems, fault diagnosis and optimum controls for heat pump systems. It is particularly notable that a substantial number of studies were dedicated for the development of air-conditioning and power recovery systems for electric vehicles in this year. (4) In building mechanical system research fields, seventeen 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, and renewable energies, piping in the buildings. Proposed designs, performance performance tests using numerical methods and experiments provide useful information and key data which can improve 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 evaluation of work noise in tunnel construction and the simulation and development of a light-shelf system. The subjects of building energy were worked on the energy saving of office building applied with window blind and phase change material(PCM), a method of existing building energy simulation using energy audit data, the estimation of thermal consumption unit of apartment building and its case studies, dynamic window performance, a writing method of energy consumption report and energy estimation of apartment building using district heating system. The remained studies were related to the improvement of architectural engineering education system for plant engineering industry, estimating cooling and heating degree days for variable base temperature, a prediction method of underground temperature, the comfort control algorithm of car air conditioner, the smoke control performance evaluation of high-rise building, evaluation of thermal energy systems of bio safety laboratory and a development of measuring device of solar heat gain coefficient of fenestration system.

Characteristics of Springtime Temperature Within Mt. Youngmun Valley (용문산 산악지역의 봄철 기온특성)

  • Chun, Ji Min;Kim, Kyu Rang;Lee, Seon-Yong;Kang, Wee Soo;Choi, Jong Mun;Hong, Soon Sung;Park, Jong-Seon;Park, Eun-U;Kim, Yong Sam;Choi, Young-Jean;Jung, Hyun-Sook
    • Korean Journal of Agricultural and Forest Meteorology
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    • v.16 no.1
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    • pp.39-50
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    • 2014
  • This paper reviews the results of recent observations in the Yeonsuri valley of Mt. Youngmun during springtime (March to May) in 2012. Automated weather stations were installed at twelve sites in the valley to measure temperature and 2, 3 dimensional wind. We examined temporal and spatial characteristics of temperatures and wind data. The Yeonsuri valley springtime average temperature lapse rate between the top and bottom of the entire period is $-0.44^{\circ}C/100$ m. It can be changed by the synoptic weather conditions, the lapse rates is greatest in order of clear days ($-0.48^{\circ}C/100$ m), rainy ($-0.41^{\circ}C/100$ m) and cloudy days ($-0.40^{\circ}C/100$ m). In the night, the temperature inversion layer (thermal belt) and the cold pool are formed within the valley. In addition, we measured temperature and wind distribution from the bottom to 3.5 m, the cold layers existed up to 1.5 m, which were affected by ground mixed layer. The results will provide useful guidance on agricultural practices as well as model simulations.

Study on the Evaluation of Radiant Heat Effects of Oil Storage Tank Fires Due to Environmental Conditions (환경조건에 따른 유류저장탱크 화재의 복사열 영향 평가 연구)

  • Lee, Jeomdong;Ryu, Juyeol;Park, Seowon;Yoon, Myong-O;Lee, Changwoo
    • Fire Science and Engineering
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    • v.34 no.1
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    • pp.72-78
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    • 2020
  • In this paper, the risk of damages to humans and properties due to fire explosions in gasoline storage tanks is identified, and the effects of radiant heat on adjacent tanks are evaluated to present the necessary area to secure safety. A simulation was conducted to evaluate the effect of radiant heat (Maximum emission) on adjacent tanks in an oil storage tank fire due to environmental conditions (Wind speed and temperature) in the Northern Gyeonggi Province. The result indicated that the radiant heat released in the fire of an oil storage tank was increased by approximately 1.9 times by the maximum wind speed and the difference occurred in the range of 700~800 kW by the maximum temperature. If a storage tank fire occurs, securing approximately 34.4 m of holding area is necessary. In the future, evaluating the radiant heat emitted by the fire of gasoline storage tanks will be required by applying various environmental conditions, and through this, research on specific and quantitative holding area is required.

Simulations of the Effect of Flow Control and Phosphate Loading on the Reduction of Algae Biomass in Gangjeong-Goryong Weir (유량 조절과 인 부하 변동에 따른 강정고령보 조류저감 효과 수치 모의)

  • Park, Dae-Yeon;Kim, Sung-Jin;Park, Hyung-Seok;Chung, Se-Woong
    • Journal of Environmental Impact Assessment
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    • v.28 no.6
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    • pp.507-524
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    • 2019
  • The purpose of this study was to validate the EFDC model for the weir pool of Gangjeong-Goryong Weir located in Nakdong River, and evaluate the effect of flow control and phosphate loading reduction on the water quality and algae biomass by group (Diatom, Green, Cyanobacteria). As a result of model validation using 2018 experimental data,the time series of water level and vertical distribution of water temperature, DO, organic matter, nitrogen, and phosphorus time series were properly simulated. Seasonal fluctuations of algae biomass by group were adequately reproduced, but the deviations between measured and simulated values were significant in some periods. As a result of scenario simulations to control the water level and flow rate, the thermal stratification was resolved as the water level was lowered and the flow rate increased. The flow velocity at which the water temperature stratification was resolved was about 0.1 m/s, which is consistent with the previous study results of Baekje Weir in Geum River. Simulations of the 2Q flow scenario showed that Chl-a decreased by 8.7% and the cell density of diatom and green algae declined. The cell density of cyanobacteria increased, however, because the high concentrations of cyanobacteria in the upstream boundary conditions directly affected downstream due to increased flow velocity. In the scenario simulation of reducing the influent phosphate load concentration (average 0.056 mg/L) to 50%, Chl-a decreased by 13.6%.The results suggest that the upstream algae concentration and phosphorus load reduction should be considered simultaneously with hydraulic control to prevent algal overgrowth of Gangjeong-Goryong Weir.

Minimum Film Boiling Temperatures for Spheres in Dilute Aqueous Polymer Solutions and Implications for the Suppression of Vapor Explosions (폴리머 수용액에서 구형체의 최소막비등온도와 증기폭발 억제 효과)

  • Bang, Kwang-Hyun;Jeun, Gyoo-Dong
    • Nuclear Engineering and Technology
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    • v.27 no.4
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    • pp.544-554
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    • 1995
  • Pool boiling of dilute aqueous solutions of polyethylene oxide polymer has been experimentally investigated for the purpose of understanding the physical mechanisms of the suppression of vapor explosions in this polymer solution. Tn solid spheres of 22.2mm and 9.5mm-diameter ore heat-ed and quenched in the polymer solutions of various concentrations at 3$0^{\circ}C$. The results showed that minimum film boiling temperature($\Delta$ $T_{MFB}$) in this highly-subcooled liquid rapidly decreased from over $700^{\circ}C$ for pure water to about 15$0^{\circ}C$ as the polymer concentration was increased up to 300ppm for 22.2mm sphere, and it decreased to 35$0^{\circ}C$ for 9.5mm sphere. This large decrease of minimum film boiling temperature in this aqueous polymer solution may explain its ability to suppress spontaneous vapor explosions. Also, tests with applying a pressure wave showed that the vapor film behaved more stable against an external disturbance at higher polymer concentrations. These observations together with the experimental evidences of vapor explosion suppression in dilute polymer solutions suggest that the application of polymeric additives such as polyethylene oxide as low as 300ppm to reactor emergency coolant be considered to prevent or mitigate energetic fuel-coolant interactions during severe reactor accidents.s.

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