• Journal of Environmental Science International
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• v.2 no.4
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• pp.331-336
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• 1993

A mathematical model for organic removal efficiency was investigated in a fluidized bed biofilm reactor by changing the feed flow rate, the residence time and the recycle flow rate. In batch experiment, organic removal could be assumed as first order and an intrinsic first order rate constant(k1) was found $6.4{\times}^{-6}cm^3/mg{\cdot}sec$ at influent COD range of 3040 - 6620 mg/L. In continuous experiment, at the condition of the influent COD, 3040 mg/L, the superficial upflow velocity, 0.47 cm/sec, the biofilm thickness 336 ${\mu}m$ and the biofilm dry density 0.091 g/mL, the calculated COD removal efficiency from the mathematical model gave 60% which was very close to the observed value of 66 %. As the feed flow rate was increased, the COD removal efficiency was sharply decreased and at constant feed flow rate, the COD removal efficiency was decreased also as the residence time being decreased.

• Journal of Korean Society for Atmospheric Environment
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• v.16 no.4
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• pp.399-408
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• 2000

This study evaluated the SO2 adsorption characteristics using a continous moving bed system. Natural manganese oxide (NMO) reaction condition such as L/D the starting time of the NMO feed, feed rate, and flow rate of simulated flue gas, and NMO size were tested. The results showed that optimum L/D was 1.0 in this moving bed system. The higher the feeding rate was the higher the SO2 removal efficiency was and the higher the flow rate of simulated flue gas was the shorter the time to reach the euqilibirum concentration was. The final SO2 con-centration when it reaches the equilibrium concentration was not affected by the starting time of the NMO feed.

• Journal of Power System Engineering
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• v.15 no.2
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• pp.25-30
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• 2011

A fresh water generation system is designed for converting brackish water or seawater into fresh water. In this paper fresh water generation by distillation process that evaporates feed water and subsequently condenses vapor as evaporation product to get fresh water was studied and city water was employed as feed water. The system uses the ejector to create a vacuum, under which liquid can be evaporated at lower temperature than it at normal or atmospheric condition, hence less energy consumption. The effect of various operating conditions i.e. temperature of feed water and different orifice diameters were studied experimentally to investigate the characteristic of the system. It was found that these parameters have significant effect in the performance of fresh water generation system with low pressure evaporation.

• Laser Solutions
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• v.5 no.1
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• pp.13-21
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• 2002

Compared to conventional welding process, laser welding does not use additional filler wire generally. However, if laser welding uses the filler wire, the applicability of the method can be broaden. When laser welding uses the filler wire, it is possible to enhance gap bridging ability and to prevent cracking in weld pool by metallurgical control. In this study, we had optimal condition and experimented gap bridging capability for butt welding with 2㎜ Al5052 alloys using the filler wire feeder. As the experimental parameters, wire feed rate and wire diameter are considered and then the performance of wire feed is evaluated under various filler wire welding conditions.

• Journal of international Conference on Electrical Machines and Systems
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• v.2 no.1
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• pp.69-76
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• 2013

This paper is concerned with speed tracking control problem for permanent-magnet synchronous drives (PMSM) in the presence of an variable load torque and unknown model parameters. The disturbance of speed control caused by inaccuracy of model parameters has been investigated. A load torque observer has been proposed to observe the load torque and estimate the disturbance caused by inaccuracy of model parameters. Both inertia and friction coefficient are identified in gradient descent approach. The stability condition of the observer has also been studied. Furthermore an improved feed-forward control has been introduced to reduce the speed track error. The proposed control strategy has been verified by both simulation and experimental results.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.3-6
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• 2002

This paper presents the cutting simulation system for prediction and regulation of cutting force in CNC machining. The cutting simulation system includes geometric model, cutting force model, and off-line fred rate scheduling model. ME Z-map(Moving Edge node Z-map) is constructed for cutting configuration calculation. The cutting force models using cutting-condition-independent coefficients are developed for flat-end milling and ball-end milling. The off-line feed rate scheduling model is derived from the developed cutting force model. The scheduled feed rates are automatically added to a given set of NC code, which regulates the maximum resultant cutting force to the reference force preset by an operator. The cutting simulation system can be used as an effective tool for improvement of productivity in CNC machining.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.6
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• pp.61-67
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• 2018

The face milling cutter, which is mainly used for the face milling, is used to cut the Carbon steel(SM20C) in the machining center for 5 times and 10 times respectively. This study clarify the dimensional accuracy characteristics according to the number of fine machining varied the condition of cutting depth, table feed speed and spindle speed. Cutting depth is varied 0.05~0.2mm, table feed speed is varied 0.05~0.2mm/min and spindle speed is varied 1500~2500rpm. As a result, the dimensional accuracy was stable 6 times machining with table feed speed 150mm/min and 10 times machining with table speed 100mm/min and cutting depth 0.05mm regardless times of machining.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.2
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• pp.143-150
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• 2000

In this paper, an optimum size for the inset cut feed of microstrip antennas has been determined by using the finite-difference time domain method. At first, the return losses of microstrip antennas having various shapes and types of the inset cut feeds have been computed numerically for a given frequency and a substrate. Then an optimum size of the inset cut feed has been determined by iterative computation procedure for a given condition. It was found that the optimum width of the inset cut feed is about 0.42 times of the width of 50Ω feed line and the optimum length of the inset cut feed is about 0.36 times of the length of the antenna patch. These results are proved by the experimental data obtained from the measurements of many fabricated antennas. It was also found that the optimum size of the inset cut feed is independent on the frequency, the height and the dielectric constant of the antennal substrate.

• Korean Journal of Veterinary Research
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• v.53 no.2
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• pp.83-88
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• 2013

Field efficacy of enterotoxigenic Escherichia coli-specific phage (${\Phi}CJ19$) as a feed additive was evaluated in weaning piglets. Fifty-four piglets at 3-4 weeks old were allocated in three different groups and two of them were fed with bacteriophage at different concentrations ($10^6PFU/kg$ feed and $10^8PFU/kg$ feed, respectively) for 30 days. Body weight and feed intake were measured at 10 days interval and body condition and fecal score were inspected every day. Based on the measurement, feed conversion rate (FCR) and average daily gain (ADG) of each group during 30 days were analyzed. The analysis suggests that the bacteriophage may help the improvement of FCR and ADG at $10^8PFU/kg$ of bacteriophage feeding group in 30 days. A result from analysis of fecal score indicates that the bacteriophage also may help to relieve the intermittent diarrhea in post-weaning stage. Those results suggest that bacteriophage might help the growth of piglets in post-weaning stage.

• Fisheries and Aquatic Sciences
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• v.27 no.7
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• pp.456-467
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• 2024

The objective of this research was to evaluate live-feed effect enriched with Moringa oleifera Leaves upon the rate of metamorphosis and survival from zoea to megalopa of Scylla olivacea larva. The study utilized a live feed consisting of Rotifer (Branchionus plicatilis) and Artemia (Artemia salina) that were supplemented with moringa leaf powder. The enrichment process involved soaking the feed in solutions containing 0, 50, 100, and 150 mg/L of the powder The levels of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were quantified following the enrichment of the live feed. A further phase involved conducting a feeding study using mud crab larvae. This experiment was conducted with three replications. Feeding mud crab larvae using rotifers starts from stage 1 of zoea to megalopa with a frequency of 2 times a day at a 30 ind/mL density, and using artemia nauplius was from the zoea 2 to megalopa with a frequency of feeding two times a day at a 5 ind/mL density. The results showed that moringa leaf powder could improve EPA and DHA more significant in Rotifer than in Artemia. Combined rotifer and Artemia nauplii enrichment with 100 mg/L of moringa leaf powder positively impacted the proximate mud crab. This treatment also implies that the metamorphosis of mud crab from zoea 1 stage to megalopa become faster than other treatment. The development from zoea 1 to megalopa stage takes around 16 days. The treatment that yielded the highest survival rate (SR) was feeding mud crab larvae with enhanced live feed containing 100 mg/L of moringa leaf powder. This study demonstrated that the incorporation of moringa leaf powder into live feed can enhance the physical condition of mud crab larvae. Furthermore, it suggests that this enrichment can accelerate the progression of developmental stages and enhance the SR of mud crab larvae when reared under controlled settings.