• Journal of Korean Society of Environmental Engineers
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• v.35 no.12
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• pp.877-882
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• 2013

The application of ultrafiltration (UF) and microfiltration (MF) membranes has been increased for drinking water purification. The advantages of UF/MF membrane process compared to conventional treatment processes are stable operation under varying feed water quality, smaller construction area, and automatic operation. Most membrane treatment plants are designed with polymeric membranes. Recently, some studies suggested that the process of treating surface water with ceramic membranes is competitive to the application of polymeric membranes. Higher water flux, less frequent cleaning, and much longer lifetime are the advantages of ceramic membrane comparing to polymeric membrane. Therefore, this research focused on the application of ceramic MF membrane pilot plant at the slow sand filtration plant. The ceramic membrane pilot plant has three trains that used raw water and sand filtered water as a feed water, respectively. For optimizing the pilot plant process, the coagulation with PACl coagulant was used as a pretreatment of ceramic membrane process. In addition, CEB (Chemical Enhanced Backwash) process using $H_2SO_4$ and NaOCl was used for 1.5 days, respectively. The experimental results showed that applying the optimum coagulant dose before membrane filtration showed enhancing membrane fluxes for both raw water and sand filtered water. Also, when using raw water as a feed of membrane, minimum fouling rate was 2.173 kPa/cycle with 25 mg/L of PACl and when using sand filtered water, the minimum fouling rate was 0.301 kPa/cycle with 5 mg/L of PACl.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.32 no.2
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• pp.144-150
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• 1987

To increase the feed value of corn stover after grain harvesting, these studies were conducted to evaluate the methods and effects of intercropping with corn and legume crops, soybean and cowpea. Basic studies were designed to detect the light receiving efficiency of intercrops with change of row-space and interrowspace under plant density of the level of 5,555 plants/l0a. Another study was conducted to select the favorable varieties for intercropping. The plant space of 90 x 20 cm was more effective to increase the light receiving effeciency of intercrop without decrease the yield of corn than that of 60 x 30 cm. Among several corn hybrid/varieties, erect leaf type was desirable for intercropping with high light penetration. Silage yield of intercropping with corn and legume crops increased above 20% without decrease of grain yield of corn compared with monocropping. The silage of intercropping appeared as a good quality roughage bulky feed with high content of crude protein and fat.

• Korean journal of applied entomology
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• v.48 no.4
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• pp.467-477
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• 2009

Host preference was tested on the 7 species plants against ggot-mae-mi, Lycorma delicatula (Hemiptera: Fulgoridae). This insect highly preferred Ailanthus altissima and Vitis vinifera however, didn't choose the other plants preferentially. Both nymphs and adults lived longest in A. altissima and V. vinifera but lived in short and low ecdysis rate against other plants and 3 species fruits. By analyzing the phloem-feeding behavior using EPG, L. delicatula was showed the short time in non-probing phase and it also exhibit the longest feeding time in A. altissima and V. vinifera, but other plants did not feed the phloem at all. In sugar contents analysis, A. altissima existed high sucrose proportion and followed by fructose>glucose, V. vinifera was analyzed by an order of glucose> fructose>maltose>sucrose>rhamnose, Malus pumila was as glucose> fructose, Pyrus calleryana was as glucose>unkown>fructose, Hibiscus syriacus was as sucrose>glucose. Nymphs and adults of L. delicatula lived longest in 5% sucrose solution, and next is in 5% fructose solution. However, they lived short in other sugar solutions. L. delicatula nymph and adult according to the combination of sugar proportion found in original plants lived longer in sugar combination solution of A. altissima and those of V. vinifera was next. Analyzed original sugar proportion from M. pumila, P. calleryana, H. syriacus respectively, L. delicatula lived short period comparing to the A. altissima, V. vinifera. This result was judged that sugar contents affected on choosing the host plants.

• Asian-Australasian Journal of Animal Sciences
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• v.24 no.12
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• pp.1706-1710
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• 2011

An experiment was conducted to investigate the effects of calcium (Ca) fertilization on oxalate content in napiergrass (Pennisetum purpureum) and on some blood parameters of sheep. Re-growth napiergrass was grown with or without Ca fertilizer and offered to sheep. Eight sheep, divided into two groups of 4 animals each were used. Calcium-fertilized napiergrass was offered daily to the animals as experimental treatment, whereas without Ca-fertilized napiergrass was given to the animals as control. Results showed that there was a trend to lower soluble and total oxalate concentrations in Ca-fertilized grass than control. The Ca-fertilized grass contained (p<0.05) lower concentrations of K and Mg than control, though Ca fertilization had no affect (p>0.05) on Ca and Na concentrations in plants. Feeding of Ca-fertilized grass had no affect on the feed consumption, blood Mg level and daily gain of sheep. However, sheep fed control grass had lower (p<0.05) blood Ca level than sheep fed Ca-fertilized grass. Our findings suggest that Ca fertilization might minimize the negative effects of oxalate.

• Economic and Environmental Geology
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• v.37 no.1
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• pp.113-119
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• 2004

Mineral wastes are generated by the minerals, mining, and metal industries. These are generally inorganic waste streams of mainly waste rock or residues from refining during extraction of metals or minerals from the ore. There are many plants where minerals are recovered in secondany circuits, treating tailings, where the feed grades are much lower than would be economic on a mined ore. The world is now becoming aware of the finite nature of its resources at a price, and of the ever-increasing development costs of large new mines. Reprocessing of old tailings on a large scale must be worth examining very seriously by those with access to sufficient material of this type. In the present paper, mineral separation techniques to recover valuable metals and resources from the old tailings are reviewed, and new trends for future developments are also discussed.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.21 no.11
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• pp.1029-1035
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• 2011

Pressure pulsation of exciting sources that generally occurs on the piping system connected to the discharge of BFP(boiler feed water pump) in power plants causes wave reflection, wave interference, resonance, standing wave and so on. But if the operating speed of the pump is changed, the state of the noise and vibration can be done because characteristics of the exciting source are changed. This paper is to investigate the cause of the noise and vibration occurring on the piping system when the operating speed of BFP is down in accordance with lowering of the power generation. It is approached to two points of view ; Firstly, it is examined whether the pulsation source impacts on the shell mode vibration that vibrates radially across the cross-section of the pipe. But it doesn't affect the shell mode as much as the resonance occurs. Secondly, to find the relation between the pulsation source and the acoustic mode of the piping system, analysis for the piping system by indirect BEM(boundary element method) is carried out. Therefore it is investigated that the mechanism of the noise and vibration relates with acoustic mode of the piping system.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.62 no.1
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• pp.36-44
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• 2013

This paper is written for the development and application of boiler fuel control algorithm and distributed control system of coal-fired power plant by the steps of design, coding, simulation test, site installation and site commissioning test. Fuel control algorithm has the upper algorithm and it is boiler master control algorithm that controls the fuel, feed water, air by generation output demand. Generation output demand by power load influences fuel control. Because fuel can not be supplied fast to the furnace of boiler, fuel control algorithm was designed adequately to control the steam temperature and to prevent the explosion of boiler. This control algorithms were coded to the control programs of distributed control systems which were developed domestically for the first time. Simulator for coal-fired power plant was used in the test step. After all of distributed control systems were connected to the simulator, the tests of the actual power plant were performed successfully. The reliability was obtained enough to be installed at the actual power plant and all of distributed control systems had been installed at power plant and all signals were connected mutually. Tests for reliability and safety of plant operation were completed successfully and power plant is being operated commercially. It is expected that the project result will contribute to the safe operation of domestic new and retrofit power plants, the self-reliance of coal-fired power plant control technique and overseas business for power plant.

• Environmental Engineering Research
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• v.16 no.4
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• pp.205-212
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• 2011

Reverse osmosis (RO) technology has developed over the past 40 years to control a 44% market share in the world desalting production capacity and an 80% share in the total number of desalination plants installed worldwide. The application of conventional and low-pressure membrane pretreatment processes to seawater RO (SWRO) desalination has undergone accelerated development over the past decade. Reliable pretreatment techniques are required for the successful operation of SWRO processes, since a major issue is membrane fouling associated with particulate matter/colloids, organic/inorganic compounds, and biological growth. While conventional pretreatment processes such as coagulation and granular media filtration have been widely used for SWRO, there has been an increased tendency toward the use of ultrafiltration/microfiltration (UF/MF) instead of conventional treatment techniques. The literature shows that both the conventional and the UF/MF membrane pretreatment processes have different advantages and disadvantages. This review suggests that, depending on the feed water quality conditions, the suitable integration of multiple pretreatment processes may be considered valid since this would utilize the benefits of each separate pretreatment.

• Proceedings of the KIEE Conference
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• 2006.07d
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• pp.1885-1886
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• 2006

The thermal energy from nuclear fission is transferred to the steam generator which is a kind of a large heat exchanger. After the feedwater is injected into the steam generator and absorbs the thermal energy, it is converted into the steam. This steam goes into the turbine. The balance between the generated energy and the consumed energy is required for the nuclear power plant to be stable. For the purpose of which, the feed water, a parameter for energy transfer, should be controlled in stability. Usually, the nuclear power plants are operated in base load in the view of power system for the stability of fission system. Therefore, though there will be almost no unbalance, there can be some instability from unbalance in case of startup/shutdown or disturbance. In this case, the controllability of feedwater pump is very important for the quick recover of stability.

• Journal of Energy Engineering
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• v.12 no.2
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• pp.74-83
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• 2003

In the advanced nuclear power plants including APR1400, the SDVS (Safety Depressurization and Vent System) is adopted to increase the plant safety using the concept of feed-and-bleed operation. In the case of the TLOFW (Total Loss of Feedwater), the POSRV (Power Operated Safety Relief Value) located at the top of the pressurizer is expected to open due to the pressurization of the reactor coolant system and discharges steam and/or water mixture into the water pool, where the mixture is condensed. During the condensation of the mixture, thermal-hydraulic loads such as pressure and temperature variations are induced to the pool structure. For the pool structure design, such thermal-hydraulic aspects should be considered. Understanding the phenomena of the submerged steam jet condensation in a water pool is helpful for system designers to design proper pool structure, sparger, and supports etc. This paper reviews and evaluates the steam jet condensation in a water pool on the physical phenomena of the steam condensation including condensation regime map, heat transfer coefficient, steam plume, steam jet condensation load, and steam jet induced flow.