• Membrane and Water Treatment
• /
• v.13 no.1
• /
• pp.39-49
• /
• 2022

Seawater desalination is doubtlessly a viable option to supply fresh drinking water. Nevertheless, RO (reverse osmosis) desalination plants in specific areas may be intermittently operated to match the imbalance between water demand and supply. Although a handful of works have been done on other membrane systems, few studies have attempted to mitigate fouling in intermittent RO systems. Accordingly, the objectives of this paper were to examine the effect of the intermittent operation on RO fouling; and to compare four intermittent operation modes including feed solution recirculation, membrane storage in the feed solution, deionized water (DI) recirculation, and membrane storage in DI water. Results showed that intermittent operation reduced RO fouling under several conditions. However, the extents of fouling mitigation were different depending on the feed conditions, foulant types, and membrane lay-up methods. When the feed solution was recirculated during the lay-up, the restoration of the flux was less significant than that by the feed solution feed-up. The use of deionized water during the lay-up was effective to restore flux, especially when the feed solution contains scale-forming salts (CaSO₄) and/or colloidal silica.

• Journal of Korean Society for Atmospheric Environment
• /
• v.26 no.2
• /
• pp.151-160
• /
• 2010

Particles emitted from three coal-fired power plants burning bituminous and sub-bituminous coals were examined for PM and size fractions PM>2.5 and PM2.5. The ratio of PM2.5/PM was ranged from 10 to 62%, and PM emission increased with the amount of coal feed, which was 7.23~15.66 kg/h. The emission range of PM2.5 from three power plants was 1.24~4.48 kg/h (dry), which was function of the mixed rate of viscous sub-bituminous coal in feed. Of course such effect should be examined by further tests in details. Based on the consumed coal and thermal load, the emission factors averaged were shown as 59.03 g-PM/ton-coal, 14.79 g-PM2.5/ton-coal and 22.51 g-PM/MWh, 5.54 g-PM2.5/MWh, respectively.

• Journal of the Korean Applied Science and Technology
• /
• v.22 no.1
• /
• pp.62-70
• /
• 2005

Step-feed process for biological nitrogen removal were analyzed numerically for the each unit and final total nitrogen(TN) effluent by water quality management(WQM) model and the results were compared data from these wastewater treatment plants. No bugs and logic error were occurred during simulation work. All of the simulation results tried to two times were obtained and both results were almost same as this model has become good reappearance. It was concluded that most of nitrogen removal occurred in the first oxic tank. Thus the controlling of the first anoxic tank may be more important in term of nitrogen removal. Also each unit of simulation result was kept good relationship with that of measured data. Accordingly this WQM model has good reliance. Finally, WQM model can predict final TN effluent within ${\pm}6.0mg/{\ell}$.

• Plant Journal
• /
• v.7 no.1
• /
• pp.56-63
• /
• 2011

The identifying cause of leakage problems on mechanical seal in a feed water pump of power plant have been difficult because of technical limits of domestic mechanical seal manufacturer and the various conditions of power plants. This paper can get a conclusion through the consideration study and experiment test of mechanical seal characteristics of feed water pump depending on oxygen treatment as follows. The oxygen treatment increase dissolved oxygen and cause a corrosion on the mechanical seal stationary ring composed of antimony as well as leakage problems. For solving leakage problems of seal, to eliminate dissolved oxygen in the cooling water of seal with hydrazine injection can prevent leakage problems of mechanical seal in feed water pump.

• Korean Journal of Poultry Science
• /
• v.45 no.1
• /
• pp.1-15
• /
• 2018

Salmonella infections in livestock industry cause various problems such as worsening animal welfare and productivity, damaging consumer confidence in the food safety of animal products. Chicken meat and eggs are known as major source of pathogen causing human foodborne infections. Therefore food safety concerns have prompted the poultry producers and governments to introduce the strategy and regulation to control these pathogens. Salmonella can persist for long periods of time in a wide range of spaces including feed bin, feed processing facilities, poultry farm, slaughterhouse, processing plants, etc. For the effective and constant Salmonella control, combination of pre-harvest, harvest and post-harvest measures should be considered comprehensively. The control measures would be most effective at farm level where the contamination initiates. Transmission of pathogen from feed origin to the live poultry and finally to the products was proven already. To control bacteria in the feed ingredients and formula feed, thermal processing, irradiation or chemical treatment may be applied. Chemical treatments to inhibit Salmonella in the feed involve the use of products containing organic acids, formaldehyde, or a combination of such compounds. However, recontamination which might occur during storage and transport process and/or by other various factors should always be under control and eliminated. Feed additives used to control Salmonella in birds' gastrointestinal track can be of various types, including prebiotics, probiotics, organic acids and bacteriophages. Although their mode of action varies, they ultimately inhibit the colonization of Salmonella in the gut and improve the performance of birds. This review describes the strategies that could be adapted to the management of feedstuffs and the use of feed additives in pre-harvest stage to control Salmonella contamination in poultry farming.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2011.04a
• /
• pp.648-654
• /
• 2011

The feed-water piping system constitutes a complex flow impedance network incorporating dynamic transfer characteristics which will amplify some pulsation frequencies. Understanding pressure pulsation waves for the feed-water recirculation piping system with cavitation problem of flow control valve is very important to prevent acoustic resonance. Feed water recirculation piping system is excited by potential sources of the shock pulse waves by cavitation of flow control valve. The pulsation becomes the source of structural vibration at the piping system. If it coincides with the natural frequency of the pipe system, excessive vibration results. High-level vibration due to the pressure pulsation affects the reliability of the plant piping system. This paper discusses the piping vibration due to the effect of shock pulsation by the cavitation of the flow control valves for the recirculation piping of feed-water pump system in combined cycle power plants.

• Asian-Australasian Journal of Animal Sciences
• /
• v.16 no.1
• /
• pp.116-123
• /
• 2003

Forages are the most important feed resource for ruminants worldwide, whether fed as pastures, forage crops or conserved hay, silage or haylage. There is large variability in the quality of forages so measurement and prediction of feeding value and nutritive value are essential for high levels of production. Within a commercial animal production system, methods of prediction must be inexpensive and rapid. At least 50% of the variation in feeding value of forages is due to variation in voluntary feed intake. Identification of the factors that constrain voluntary feed intake allows these differences to be managed and exploited in forage selection. Constraints to intake have been predicted using combinations of metabolic and physical factors within the animal while simple measurements such as the energy required to shear the plant material are related to constraints to intake with some plant material. Animals respond to both pre- and post-ingestive feedback signals from forages. Pre-ingestive signals may play a role in intake with signals including taste, odour and texture together with learned aversions to nutrients or toxins (post-ingestive feedback signals). The challenge to forage evaluation is identification of the factors which are most important contributors to these feedback signals. Empirical models incorporating chemical composition are also widely used. The models tend to be useful within the ranges of the datasets used in their development but none can claim to have universal application. Mechanistic models are becoming increasingly complex and sophisticated and incorporate both feed characteristics and use of biochemical pathways within the animal. Improvement in utilisation through the deliberate selection of pasture plants for high feeding value appears to have potential and has been poorly exploited. Use of Near Infrared Reflectance Spectroscopy is a simple method that offers significant potential for the preliminary screening of plants with genetic differences in feeding value. Near Infrared Reflectance Spectroscopy will only be as reliable as the calibration sets from which the equations are generated.

• Preventive Nutrition and Food Science
• /
• v.11 no.1
• /
• pp.25-30
• /
• 2006

It is of utmost importance to feed the current world population by improving agricultural production with newer varieties of food crops, but what is still more important is to add nutrition into the food. Some of the plants, which are currently growing in the wastelands, contain certain phytochemicals which add to their neutraceutical and health value. These plants contain secondary metabolites which enhance the over all metabolic functions of the body. Withasteroids are one of such phytochemicals. These chemicals are almost exclusively found in plants of the Solanaceae family; one of which, Physalis minima, contains several with asteroids. The aerial parts and roots of P. minima have been found to contain several steroids, identification of which is been discussed in this paper. These with asteroids contribute to the functional value since incorporation of withanolides in the diet may prevent or decrease the growth of tumors in humans.

• Korean Journal of Construction Engineering and Management
• /
• v.16 no.5
• /
• pp.65-76
• /
• 2015

FEED (Front End Engineering and Design) is the key area that determines the competitiveness of procurement and construction in the EPC contracts especially in terms of the added value. Nevertheless, previous researches in FEED have been limited to the process and deliverable of design work or the particular management business function (e.g. System Engineering, collaboration, information etc.). In this context, the purpose of this study is to propose a comprehensive FEED structure and its functions from the project management perspective throughout the whole project life-cycle for thermal power plants. Proposed FEED business procedures are classified into three levels; First level is the classification of FEED business phases, the second level defines major FEED management functions, and the third level is detailed FEED functions. A survey using proposed FEED functions and assessment variable was conducted in order to analyze the current status and the areas for future improvement. It is expected that the proposed structure, functions, and evaluation methodology for FEED management will contribute to effective practice of FEED as well as to improvement of competitive capability for engineering, procurement, and construction (EPC) companies.

• Proceedings of the SAREK Conference
• /
• 2009.06a
• /
• pp.847-852
• /
• 2009

Feedwater heaters of many nuclear power plants have recently experienced severe wall thinning damange, which will increase as operating time progresses. Several nuclear power plants in Korea have experienced wall thinning damage in the area around the impingement baffle inside feed-water heater installed downstream of the turbine extraction stream line. At that point, the extract steam from the turbine is two phase fluid at high temperature, high pressure, and high speed. Since it flows to reverse direction after impinging the impingement baffle, the shell wall of feedwater heaters may be affected by flow-accelerated corrosion. In this paper, to compare wall thinning range according to change entrance nozzle diameter and position with reference numerical analysis model's wall thinning range, various numerical analysis models applied. In case of changing diameter, four different diameter is applied. And a side of nozzle position, two different position-vertical type and parallel type-is applied. And then this paper describes operation of numerical analysis which is composed similar condition with real feed water heater. In conclusion, this study shows effective design for shall wall thinning by changing nozzle diameter and position.