• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.3 s.357
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• pp.7-17
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• 2007

An analysis and design theory of an aperture-coupled cavity-fed back-to-back microstrip directional coupler is presented for the efficient and optimized design. For this purpose, an equivalent network is developed, and simple but accurate calculations of circuit element values are described. Design equations of the coupler are derived based on the equivalent circuit. In order to determine various structural design parameters, the evolutionary hybrid optimization method based on the genetic algorithm and Nelder-Mead method is invoked. As a validation check of the proposed theory and optimized design method, a 10 dB directional coupler was designed and fabricated. The measured coupling was 10.3 dB at 3 GHz, and the return loss and isolation were 31.8 dB and 30.5 dB, respectively. The directional coupler also showed very good quadrature phase characteristics. Good agreements between the measured and the design specifications fully validate the proposed network analysis and design procedure.

• Journal of Animal Science and Technology
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• v.48 no.5
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• pp.663-670
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• 2006

The present study was performed to investigate the effect of plant type recombinant porcine somatotropin (pST) adminstration on growth performance and blood profile of finishing pigs. Forty-eight Landrace barrows weighing 78 kg were employed for six week growth trial. Twelve barrows were allocated into various rpST types ; the control (CONT), the 4:1 type rpST (TRT 1), the 1:1 type rpST (TRT 2); and the 4:1 type rpST group(TRT 3) respectively. CONT group were not planted rpST. TRT 1 group was treated with rpST once a week for 6 weeks. Each dose contained the rpST equivalent to 100mg from initial to two weeks and 125mg from three weeks to finial week. TRT 2 and TRT 3 groups were planted rpST four times contained the rpST equivalent to 100mg during trial period from initial to two weeks, and 125 mg from three weeks, to four weeks, respectively. All pigs were fed a commercial feed containing 0.9% lysine ad lib. Daily gain increased by 19.4% in TRT 1(p<0.05) compared to the CONT. rpST improved feed/gain by 13.4～28.9% in all treatment groups(p<0.05). Back fat thickness of the all rpST treated groups were 23.3～29.2% thinner than that of the CONT. These results indicated that the rpST stimulated growth performance in finishing pigs and plant type rpST could be used as a growth stimulant for finishing pigs.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.39 no.6
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• pp.709-717
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• 2002

A new multi constant modulus algorithm (MCMA) for a blind decision feedback equalizer is proposed. In order to avoid the error propagation problem in the conventional DFE structure, Feed-Back Filter coefficients are updated only after Feed-Forward Filter coefficients are sufficiently converged to the steady state. Therefore, it has the problem of slow convergence speed characteristics. To overcome this drawback, the proposed MCMA algorithm uses not only new cost function considering the minimum distance between the received signal and the representative value containing the statistical characteristics of the transmitted signal, but also adaptive step-size according to the equalizer outputs to fast convergence speed of FBF. Simulations were carried out under the certified communication channel environment to evaluate a performance of the proposed equalizer. The simulation results show that the proposed equalizer has an improved convergence and SER performance compared with previous methods. The proposed techniques offer the possibility of practical equalization for cable modem and terrestrial HDTV broadcast (using 8-VSB or 64-QAM) applications.

• Korean Business Review
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• v.21 no.2
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• pp.171-194
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• 2008

In this study, specific review for the recent trend both in technical parts and the contents of IFE will be revealed. At the same time, how the passenger's satisfaction on IFE will lead to make an intention of repurchase and create the transmission of positive feed backs on the concerned airline has been thoroughly studied. In order to do the above, 250 air traveling passengers has participated the survey and 235 survey forms has been analyzed by Multiple Regression Analysis. According to the analysis, the physical environmental Improvement in aircraft system helps to Increase the satisfaction degree on IFE. The convenience is revealed as the most effective factor in the satisfaction degree on IFE while the atmosphere and design is regarded as the similarly Important factor. The contents of IFE are obviously affecting the satisfaction degree in positive side. Consequently, the customers' satisfaction on IFE positively affects to the repurchase intention especially to the transmission of the feed back.

• Korean Journal of Agricultural Science
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• v.44 no.2
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• pp.228-234
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• 2017

Feed intake (FI) of sows during lactation is a serious problem because sows require a large amount of energy for high milk production during lactation. Providing a palatable diet is important for lactating sows to cope with the stress of breast-feeding. Palatability can be increased by adding sweeteners to diets. This study was conducted to evaluate the effects of saccharin (sweetener) on growth performance, fecal moisture, and litter performance of lactating sows. Sixteen sows were randomly allotted to one of two dietary treatments in a 27-day trial starting from lactation. The two dietary treatments were supplemented with 0 and 0.2% saccharin (sweetener), respectively. Average daily feed intake (ADFI) was increased (p < 0.05) and back fat loss (BFL) was decreased (p < 0.05) in sows fed saccharin supplementation diets compared with sows fed control diet during lactation. However, sows' body weight loss, body condition score (BCS), fecal score, and the number of piglet survival were not different (p > 0.05) among dietary treatments. The two dietary treatments also had no significantly different effect (p > 0.05) on litter weight and average daily gain (ADG) of piglets. Taken together, saccharin has no significant effect on growth performance of piglets but it can increase FI and reduce BFL of lactating sows.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.8
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• pp.1765-1772
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• 2015

In the underwater acoustic communication channels, multipath reflection become the cause of obstacle. Generally, equalizer has been applied to overcome these problems. In this paper, the method was proposed to optimize tap-length of decision feedback equalizer using genetic algorithm. After inputting feed-forward filter length and feed-back filter length as genetic information of the genetic algorithm, it optimize tap-length using BER(bit error rate) calculation in accordance with object function. The object function consist of decision feedback equalizer and BER calculation. For the purpose of BER calculation in the object function, the method was proposed to optimize the tap-length of decision feedback equalizer with genetic algorithm using preamble signals. As a result of experiments, the optimized BER is 0.0355 for signals which were received through a 25m receiver and which were applied to calculate BER merely using preamble signals in object function. When all data were used to calculate BER in object function, the optimized BER is 0.0215.

• Korean Membrane Journal
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• v.7 no.1
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• pp.1-18
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• 2005

The permeate flux decline due to membrane fouling can be addressed using a variety of theoretical stand-points. Judicious selection of an appropriate theory is a key toward successful prediction of the permeate flux. The essential criterion f3r such a decision appears to be a detailed characterization of the feed solution and membrane properties. Modem theories are capable of accurately predicting several properties of colloidal systems that are important in membrane separation processes from fundamental information pertaining to the particle size, charge, and solution ionic strength. Based on such information, it is relatively straight-forward to determine the properties of the concentrated colloidal dispersion in a polarized layer or the cake layer properties. Incorporation of such information in the framework of the standard theories of membrane filtration, namely, the convective diffusion equation coupled with an appropriate permeate transport model, can lead to reasonably accurate prediction of the permeate flux due to colloidal fouling. The schematic of the essential approach has been delineated in Figure 5. The modern approaches based on appropriate cell models appear to predict the permeate flux behavior in crossflow membrane filtration processes quite accurately without invoking novel theoretical descriptions of particle back transport mechanisms or depending on adjust-able parameters. Such agreements have been observed for a wide range of particle size ranging from small proteins like BSA (diameter ${\~}$6 nm) to latex suspensions (diameter ${\~}1\;{\mu}m$). There we, however, several areas that need further exploration. Some of these include: 1) A clear mechanistic description of the cake formation mechanisms that clearly identifies the disorder to order transition point in different colloidal systems. 2) Determining the structure of a cake layer based on the interparticle and hydrodynamic interactions instead of assuming a fixed geometrical structure on the basis of cell models. 3) Performing well controlled experiments where the cake deposition mechanism can be observed for small colloidal particles (< $1\;{\mu}m$). 4) A clear mechanistic description of the critical operating conditions (for instance, critical pressure) which can minimize the propensity of colloidal membrane fluting. 5) Developing theoretical approaches to account for polydisperse systems that can render the models capable of handing realistic feed solutions typically encountered in diverse applications of membrane filtration.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.3
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• pp.181-186
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• 2017

Single point incremental forming (SPIF) is a sheet-forming technique. It is a die-less sheet metal manufacturing process for rapid prototyping and small batch production. The Critical parameters in the forming process include tool diameter, step depth, feed rate, spindle speed, etc. In this study, these parameters and the die shape corresponding to the Varying Wall Angle Conical Frustum(VWACF) model were used for forming 0.8mm in thick Al5052-O sheets. The Taguchi method of Experiments of Design (DOE) and Grey relational optimization were used to determine the optimum parameters in SPIF. A response study was performed on formability, spring back, and thickness reduction. The research shows that the optimum combination of these parameters that yield best performance of SPIF is as follows: tool diameter, 6mm; spin speed, 60rpm; step depth, 0.3mm; and feed rate, 500mm/min.

• Korean Journal of Poultry Science
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• v.30 no.4
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• pp.269-273
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• 2003

A cecostomy technique (surgery for inserted tube into ceca) was developed to quantify urine backflow into the ceca of fed and feed-deprived chickens. Two days post-surgery, cecostomised chickens were flushed with 20ml of warm saline solution every other day for 10 days. Excreta were collected daily from cecal tubing and cloaca by surgical attachment of polyethylene collection vessels to the chickens. Uric acid excretion was significantly increased in fed compared to feed-deprived chickens (P<0.05). Amount of determined uric acid from the ceca was 7.74% and 5.31% of total excretion for fed and ffeed-deprived chickens, respectively. Post-mortem examinations ascertained that the caeca were intact around the Latex tubing. The results of the study indicated that at least 5% of daily urine production flow retrograde into the ceca of roosters.

• Korean Journal of Agricultural Science
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• v.48 no.3
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• pp.387-396
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• 2021

This study was conducted to provide basic data for efficient Hanwoo beef production by conducting a comparison of growth performance, blood metabolites, testosterone, and carcass characteristics of Hanwoo according to complete and hemi-castration. Twelve Hanwoo calves were allotted to two treatment groups as follows: CC = complete-castration and HC = hemi-castration method of removing only one testicle. At the end of the test, the body weight was 66 kg higher in HC than in CC, and the average daily gain increased by 12.6% (p < 0.05). The feed conversion ratio was significantly improved in HC compared to CC (p < 0.05). Serum cholesterol and triglyceride concentrations were significantly higher in CC than HC in both the growing and fattening periods (p < 0.05), and serum testosterone concentrations before castration were similar between HC and CC, but steadily increasing in HC after castration. Back fat thickness and marbling score were significantly higher in CC than HC in the entire period (p < 0.01). In the results of this study, hemi-castration can improve body weight gain and feed conversion ratio due to the influence of male hormones compared to complete castration, but it is considered that there will be difficulties in producing high-quality meat with a high marbling score.