• The Journal of the Acoustical Society of Korea
• /
• v.6 no.4
• /
• pp.5-11
• /
• 1987

In this paper, the measurement of SAW velocity on piezoelectric ceramic is studied. It can be done by using oscilloscope and pulse generator, and measure the velocity especially when feed-through is appeared. The propagating distance was exactly calculated considering that IDT responses are obtained by convolution theory, therefore the velocity was measured by the above simple method. As the results, the measurement velocity at room temperature was 3480 m/sec for $YZ-LiNbO_3$ single crystal and 2770 m/sec for a family of $PbTiO_3$ceramics with feed-through signal.

• Journal of Environmental Science International
• /
• v.30 no.3
• /
• pp.289-293
• /
• 2021

This study was conducted to investigate the distribution of duck production in duck housing as a function of the breeding period. The items in duck production distribution included body weight, feed intake, feed conversion ratio, and average duck production. All data were based on eight cycles (June and December, 2017; February, June, August, September, and November, 2018; February, 2019) at Farm Site 1 through 7. The most optimal results in the duck production distribution were observed at Site 1 for weight gain, feed intake, and feed efficiency. This could be explained by the fact that Site 1 was well managed in environmental improvement and sustainability. Based on these data, selective alternatives to improve duck production in duck farms are recommended as follows: first, proper management and recording of litter used as a flooring material are required, and second, continuous management such as temperature, relative humidity and ventilation is needed. Lastly, it is necessary to change duck facilities by introducing environmental management techniques. Furthermore, efforts to improve the overall facilities and management of duck breeding farms through additional field studies are needed in the future.

• Asian-Australasian Journal of Animal Sciences
• /
• v.7 no.3
• /
• pp.435-440
• /
• 1994

Postweaning performance data were obtained on 401 group fed purebred Angus calves from 24 selected sires (12 high and 12 low feed conversion sires) from 1983 through 1986 at the Northwestern Branch of the Ohio Agricultural Research and Development Center. The objective of this study was to determine the interrelationships between body measurements and 140-d feed conversion (feed/gain) adjusted for maintenance (ADJFC), 140-d feed conversion unadjusted for maintenance (UNADFC) and feed conversion measured until progeny reached 8.89 mm of backfat (FC). Variables measured at the completion of the 140-d postweaning period included hip peight (HH), chest depth (CD), chest width (CW), head width (HDW), head length (HDL), heart girth (HG), muzzle circumference (MC), backfat thickness (BF), length between hooks aod pins (HOPIN) and length between shoulder and hooks (SHHO). Measurements were taken from progeny born from 1983 through 1986 for HH and BF, while others, except chest measurements (CD and CW), which were available only in 1985, were taken from progeny born in 1985 and 1986. Negative phenotypic correlations were found for UNADFC, ADJFC and FC. respectively, with HG (-0.76, -0.65 and -0.85), HOPIN (-0.05, -0.28 and -0.09), HDL (-0.63, -0.66 and -0.57), MC (-0.12, -0.35 and - 0.25), HH (-0.38, -0.29 and -0.001), BF(-0.29, -0.31 and -0.12) and CW (-0.03, -0.35 and -0.58). In general, fatter animals with larger HG, longer HDL and greater MC had better feed conversion.

• Journal of IKEEE
• /
• v.17 no.1
• /
• pp.10-15
• /
• 2013

This paper, we analyzed that the measured data of the radiated power spectrum of electromagnetic waves of the normal spark ignition system and the spark ignition system with feed through type ceramic condenser. The results show that the strength of power spectrum radiated from the system with feed through type ceramic condenser is weaker than the normal system, and the density of power spectrum radiated from the system with feed through type ceramic condenser is smaller than the normal system. From these results, the feed through type ceramic condenser can reduce the electromagnetic waves radiating from the spark ignition system which is the spurious emission, and it can be concluded that the ignition coil of the spark ignition system generating high voltage pulse is equivalent to the radio frequency oscillator which is oscillating high frequency from a electronic point of view.

• Journal of Biosystems Engineering
• /
• v.16 no.2
• /
• pp.148-158
• /
• 1991

This study was undertaken to develop the feed rate control system for the head feed thresher by making use of the microprocessor and to evaluate the response of the system to a various threshing conditions. It was verified the performance of the control system through experiments. Control conditions were determined based on the simulation results of control system. The control system set at RH=500rpm, RL=480rpm for the bundle feed was considered optimum to give a high threshing capability and still to stabilize the feeding seed regardless of the bundle size. The control system for the continuous spread feed set at the range of LH=15mm, and LL=12mm gave a high control performance for the feeding mass of 1.1Kg/m and lower tested. In addition, the feed rate proportionality constant should be set lower than one in order to keep the rotational speed of threshing cylinder within the range of 500~520rpm.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2003.06a
• /
• pp.141-144
• /
• 2003

This paper proposes an analytical model of off-line feed rate scheduling to obtain an optimum feed rate for high speed machining. Off-line feed rate scheduling is presented as an advanced technology to regulate cutting forces through change of feed per tooth, which directly affects variation of uncut chip thickness. In this paper, the feed rate scheduling model was developed using a mechanistic cutting force model using cutting-condition-independent coefficients. First, it was verified that cutting force coefficients are not changed with respect to cutting speed. Thus, the feed rate scheduling model using the cutting-condition-independent coefficients can be applied to set the proper feed rates for high speed machining as well as normal machining. Experimental results show that the developed fred rate scheduling model makes it possible to maintain the cutting force at a desired level during high speed machining.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 2000.04a
• /
• pp.240-245
• /
• 2000

This paper presents the experimental study of drilling for duralumin A2024 with intermittently decelerated feed rate. It is achieved through a programmed periodic increase and decrease in the feed rate using a machining center. The following experimental result were performed with the objective of solving chip to disposal problems. In conventional drilling of aluminum, long continuous chips are produced that wind around the drill causing difficulties in eliminating chips from the cutting zone. In order to acquire the basic data necessary to regulate the chip profile, the relationship between cutting variables and chip shape was investigated. The following conclusions are established from the experimental results. At a suitable feed fluctuation ratio, intermittently decelerated feed drilling proved successful in breaking chips to appropriate lengths while maintaining stable cutting. Thus, it is an effective method for improving chip disposal. The amplitude of the dynamic component of cutting force in intermittent feed frilling is influenced by the feed fluctuation ratio.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2002.10a
• /
• pp.147-179
• /
• 2002

The important role of observational method in geotechnical engineering are emphasized together with the direction of future development, concerning successful application of the technique on the site investigation, design and feed back at various construction stages. Case histories on the application of feed back are introduced in order to achieve the most economical and reliable construction for tunnel, rock slope and deep excavations through feed back system at design and construction stages. Also the limitations and advantages of the observational method and the role of feed back system are discussed for construction of tunnel, rock slope and deep excavation in hard ground such as layered ground conditions including weathered, soft and hard rocks.

• Animal Bioscience
• /
• v.35 no.10
• /
• pp.1461-1478
• /
• 2022

The maintenance of poultry gut health is complex depending on the intricate balance among diet, the commensal microbiota, and the mucosa, including the gut epithelium and the superimposing mucus layer. Changes in microflora composition and abundance can confer beneficial or detrimental effects on fowl. Antibiotics have devastating impacts on altering the landscape of gut microbiota, which further leads to antibiotic resistance or spread the pathogenic populations. By eliciting the landscape of gut microbiota, strategies should be made to break down the regulatory signals of pathogenic bacteria. The optional strategy of conferring dietary fibers (DFs) can be used to counterbalance the gut microbiota. DFs are the non-starch carbohydrates indigestible by host endogenous enzymes but can be fermented by symbiotic microbiota to produce short-chain fatty acids (SCFAs). This is one of the primary modes through which the gut microbiota interacts and communicate with the host. The majority of SCFAs are produced in the large intestine (particularly in the caecum), where they are taken up by the enterocytes or transported through portal vein circulation into the bloodstream. Recent shreds of evidence have elucidated that SCFAs affect the gut and modulate the tissues and organs either by activating G-protein-coupled receptors or affecting epigenetic modifications in the genome through inducing histone acetylase activities and inhibiting histone deacetylases. Thus, in this way, SCFAs vastly influence poultry health by promoting energy regulation, mucosal integrity, immune homeostasis, and immune maturation. In this review article, we will focus on DFs, which directly interact with gut microbes and lead to the production of SCFAs. Further, we will discuss the current molecular mechanisms of how SCFAs are generated, transported, and modulated the pro-and anti-inflammatory immune responses against pathogens and host physiology and gut health.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.45 no.6
• /
• pp.679-685
• /
• 2012

A study was carried out to observe the effects of feed types on the growth, feed preference, and enteric feed transition rate of juvenile starry flounder, Platichthys stellatus for 45 days. Fifty fish (avg. 135 g) were stocked each in replication, and fed a commercial extruded pellet diet (EP, 45% protein) and a moist pellet diet (MP, 65% raw mackerel+35% feed powder in wet basis), respectively. The MP presented the higher performance than that of the EP on the feed efficiency ($68.3{\pm}0.9%$ for EP and $92.3{\pm}4.3%$ for MP) and the specific growth rate ($1.07{\pm}0.07$ for the EP and $1.20{\pm}0.05%$ for the MP). In contrast, the EP showed the higher feed preference in terms of the daily feed intake ($1.57{\pm}0.08%$ for the EP and $1.30{\pm}0.01$ for the MP) and the ad libitum feeding rate after a fast of 72 hours (1.73% for the EP and 1.35% for the MP). The feed transition rate through intestinal canals decreased exponentially in both the EP and the MP, showing the faster transition rate with the EP. In the result, starry flounder appeared to have the better feed preference to the EP, but have the higher feed efficiency and growth performance to the MP.