• Korean Journal of Veterinary Service
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• v.32 no.1
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• pp.77-82
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• 2009

Salmonella (S.) Typhimurium infection in pigs is a major source of human foodborne salmonellosis. Recently, the swine industry in Korea has been suffered from salmonellosis causing severe economic loss to farms. Organic acids have antibacterial activity which prevents bacteria from multiplying by reducing the pH in the gastrointestinal tract. The aim of the present study is to evaluate whether $Salstop^{(R)}$ mixed with organic acids is able to have influence on growth performance and whether it prevents against S. Typhimurium in weaning pigs. Four experimental treatments were examined: general diet added with 0.3% of $Salstop^{(R)}$ after S. Typhimurium ($1.0{\times}10^{10}CFU/ml$) challenge, group A; commercial feed after Salmonella ($1.0{\times}10^{10}CFU/ml$) challenge, group B; commercial feed and $Salstop^{(R)}$, group C; commercial feed, Group D. At the end of the study, no significant differences in daily body weight gain and feed intake were observed between groups treated with $Salstop^{(R)}$ and groups treated without, whereas feed conversion ratio (FCR) tended to be improved in groups treated with $Salstop^{(R)}$ between days 1 to 14. Serological and microbiological evolution of the infection were examined by ELISA and microbiological culture from serums and fecal samples, respectively. In groups that challenged by S. Typhimuriums, the group without $Salstop^{(R)}$ showed higher prevalence and bacterial shedding compared to the groups treated with $Salstop^{(R)}$. Our results suggest that the administration of $Salstop^{(R)}$ could be used to promote feed efficiency and to reduce the prevalence of salmonellosis in weaners.

• Journal of Preventive Medicine and Public Health
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• v.19 no.2 s.20
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• pp.281-292
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• 1986

Infection by hepatitis B virus is one of the major health problems of this nation. HBsAg positive rates of general population and school children were known to be as about 8 percent and 3.9 to 5.9 percent respectively. To study the incidence rate of hepatitis B infection in school children of rural area, author had examined 475 school children of relatively isolated agricultural area for baseline prevalence of hepatitis B virus serologic markers and followed up 415 school children during 10 months to determined the frequency of serologic conversion. The major results are summarized as followings: 1) Among the 278 susceptible children who were followed up, 26 had seroconversion for HBsAg or Anti-HBs. Therefore, the cumulative incidence rate during 10 months is estimated 9.4%. 2) The incidence rate of hepatitis B infection tends to increase with age (6-9yrs: 3.2%, 10-14yrs: 9.5%, 15-17yrs: 18.9%), and the incidence rate in male (13.0%) was higher than in female (5.7%). 3) The incidence rates of hepatitis B virus infection were not different statistically among three economic classes (The rates of lower, middle and higher class were 11.8%, 7.1% and 10.5%.). 4) The incidence rates of hepatitis B virus infection were not different statistically between visitors and non-visitors of clinic or hospital, dental clinic, persons received IV and not received IV, and persons with familial history and without familial history of liver diseases. Therefore all of these factors were not identified as risk factor of hepatitis B virus infection. And the transmissibility within the class of school was not recognized, too. 5) Among the 25 children who were HBsAg positive when enrolled, 15 (60%) were still HBsAg positive, who were identified as chronic carrier 15 of 415 school children were chronic carriers, then chronic carrier rate was estimated 3.6%, and there was no difference between sexes. 6) Of 38 children who had been Anti-HBs positive when enrolled, 5 (13.2%) lost Anti-HBs. Therefore, the loss rate of Anti-HBs per year is estimated to be 15.8%.

• Transactions of the Korean Society of Mechanical Engineers
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• v.11 no.2
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• pp.253-261
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• 1987

Thermoacoustic oscillation of an air column induced by heated wires is investigated analytically and experimentally. Acoustic power generation from a single heater wire is estimated based on the result of heat transfer analysis and expressed in terms of the efficiency factor indicating the conversion efficiency from heat to acoustic energy. It is shown that the efficiency factor becomes maximum when the wire radius is the order of the coustic boundary layer thickness and the flow velocity is close to the thermal diffusion velocity. Onset condition of the column oscillation is obtained by equating the acoustic power generation at the heater to the power loss due to thermoviscous dissipation at the tube wall and the convection and radiationloss at the open ends of the tube. In estimating the acoustic power generation, the heater is treated as a stretched single wire by correcting the flow velocity to take into account the interactions between adjacent heater wires. Experiment is performed by using a spiral heater of 1mm diameter in an air column of 37mm diameter. The heat input to drive the oscillation is measured and compared with the theoretical prediction. A good agreement is found between the theory and experiment, which is regarded as a substantial verification of the present analysis.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.41 no.2
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• pp.87-95
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• 2017

The concept of entransy has been proposed recently as a potential heat transfer mechanism and could be useful in analyzing and optimizing the heat-work conversion systems. This work presents an entransy analysis for the irreversible Carnot cycle by systematic balance formulations of the entransy loss, work entransy, and entransy dissipations, which are consistent with exergy balances. Additionally, several forms of system efficiency are introduced based on entransy for the appreciation of the optimal system performance. The effects of the source temperature and irreversible efficiencies on the optimal conditions for system efficiencies are systematically investigated for both dumping and non-dumping cases of used source fluid. The results show different trends in entransy efficiencies when compared to the conventional efficiencies of energy and exergy, and represent another method to assess the effective use of heat source in power generation systems.

• Journal of the Korean Society for Nondestructive Testing
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• v.32 no.5
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• pp.585-596
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• 2012

PVDF(poly vinylidene fluoride) and P(VDF-TrFE)(poly vinylidene fluoride-tetrafluoroethylene) are the typical piezoelectric polymers with unique properties. Even they are inferior to conventional piezoelectric ceramics PZT in electromechanical conversion efficiency and interior loss, though they are superior in receiving sensitivity and frequency bandwidth. Their acoustic impedances are relatively close to water or biological tissue and it is easier to make thin film than other piezoelectric materials. Futhermore, the film is so flexible that it is easy to attach on a complex surface. Those properties are suitable for the ultrasound transducers which are useful for medical and biological application, so that various types of polymer transducers have been developed. In this paper, several important considerations for design and fabrication of piezoelectric polymer transducers were described and their effect on the transducer performance were demonstrated through the KLM model analysis. Then, it was briefly reviewed about the structures of the polymer transducers developed for obtaining images as well as the characteristics of the images in several important medical and biological application fields.

• The Journal of Korean Institute of Information Technology
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• v.16 no.11
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• pp.23-34
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• 2018

This paper presents the high efficiency and high power-factor power supply for LED lighting equipment. The proposed power supply is the single-stage power structure consisted of the full-bridge diode rectifier and flyback converter, and thus the power-factor correction and output voltage regulation are performed simultaneously using only one controller IC and one power semiconductor switch. Furthermore, the proposed power supply reduces the voltage stress and switching loss of main switch using the regenerative snubber, and it improves the system efficiency using the synchronous rectifier. The applied synchronous rectifier is the new voltage-driven type and its operation and construction are simple. In this paper, the operation principle of proposed power supply is explained through the operation analyses of its power-factor correction and main power conversion parts and the operation of synchronous rectifier is described, briefly. Also, a design example of the power circuit of 40W-class prototype is shown and the operation characteristics of proposed power supply are validated through the experimental results of the implemented prototype by the designed circuit parameter.

• Applied Chemistry for Engineering
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• v.30 no.1
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• pp.49-53
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• 2019

Hydrous $MnO_2$ nanowires were easily synthesized by an one-pot synthesis with a simple hydrothermal method. As prepared hydrous $MnO_2$ nanowires were characterized with scanning emission microscopy (SEM), transmit emission microscopy (TEM), X-ray diffraction (XRD), and Brunauer-Emmett-Teller (BET). They showed a good catalytic activity with the suitable nano-size of 4-5 nm and morphology. The furfuryl alcohol was selected as a substrate and the reaction was carried out in a toluene solvent at $100^{\circ}C$ under the atmospheric pressure of oxygen. The hydrous $MnO_2$ nanowire catalyst exhibited an excellent yield of furfural with the first-rate selectivity and conversion. The catalytic performance during recycle tests was also carried out and the catalyst showed a good mechanical strength with a negligible loss in the activity over five reaction cycles.

• The Journal of the Acoustical Society of Korea
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• v.38 no.4
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• pp.427-432
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• 2019

In this paper, we propose a home monitoring system using sound event detection based on a bidirectional gated recurrent neural network for the hard-of-hearing. First, in the proposed system, packet loss concealment is used to recover a lost signal captured through wireless sensor networks, and reliable channels are selected using multi-channel cross correlation coefficient for effective sound event detection. The detected sound event is converted into the text and haptic signal through a harmonic/percussive sound source separation method to be provided to hearing impaired people. Experimental results show that the performance of the proposed sound event detection method is superior to the conventional methods and the sound can be expressed into detailed haptic signal using the source separation.

• Korean Journal of Agricultural Science
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• v.48 no.3
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• pp.423-432
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• 2021

This experiment was conducted to investigate the effect of Cordyceps militaris with probiotics (CMP) supplementation on the growth performance, meat quality and storage characteristics, and cordycepin content in the meat. Sixty one-day-old broilers (Ross 308) were allotted to two treatment groups of 30 each. In addition, six broilers were randomly assigned to a cage in the two treatment groups. The two dietary treatments were as follows: Control (CON) and basal diet + 0.5% of CMP. Body weight and feed intake were measured on the 1st, 14th, and 28th days from the start of the experiment. On days 1 - 14, the supplementation of CMP improved (p < 0.05) the body weight gain (BWG) and feed conversion ratio (FCR). Additionally, the feed intake (FI) and FCR scores in the CMP groups improved (p < 0.01) compared to the CON during the entire period. For the meat quality characteristics, water holding capacity (WHC), cooking loss (CL), redness (a^*) in meat color value, and shearing force (SF) for the CMP group were improved (p < 0.01) compared to the CON group. For the meat storage characteristics, pH and thiobarbituric acid reactive substances (TBARS) were improved (p < 0.01) when the broilers were fed CMP compared to the CON group. Broilers fed CMP had a higher (p < 0.01) cordycepin content in the meat compared to the CON group. In conclusion, CMP improves the growth performance and meat quality of broilers.

• Journal of the Korea Convergence Society
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• v.12 no.2
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• pp.7-13
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• 2021

This paper introduces an algorithm that compensates for missing values after converting them into a format that can represent the probability for incomplete data including missing values in training data. In the previous method using this data conversion, incomplete data was processed by allocating missing values with an equal probability that missing variables can have. This method applied to many problems and obtained good results, but it was pointed out that there is a loss of information in that all information remaining in the missing variable is ignored and a new value is assigned. On the other hand, in the new proposed method, only complete information not including missing values is input into the well-known classification algorithm (C4.5), and the decision tree is constructed during learning. Then, the probability of the missing value is obtained from this decision tree and assigned as an estimated value of the missing variable. That is, some lost information is recovered using a lot of information that has not been lost from incomplete learning data.