• Journal of the Korean Society of Propulsion Engineers
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• v.17 no.1
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• pp.70-79
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• 2013

In this work, a steady-state performance modeling and off-design performance analysis of the 2-spool separate-flow turbofan engine named (BR715-56) which is a power plant for the narrow body commercial aircraft is carried out for engine performance behaviors investigation and condition monitoring using a commercial code MATLAB/SIMULINK. Firstly, the engine component maps of fan, high pressure compressor, high pressure turbine and low pressure turbine are generated from similar component maps using the scaling method, and then the off-design performance simulation model is constructed by the mass flow matching and the work matching between components. The model is developed using SIMULINK, which has advantages of easy steady-stare and dynamic modelling and user friendly interface function. It is found that the off-design performance analysis results using the proposed model are well agreed with the performance analysis results by GASTURB at various operating conditions.

• Structural Engineering and Mechanics
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• v.59 no.3
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• pp.559-577
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• 2016

There are many theoretical analyses and experimental studies of the hydrodynamics for the tension leg platform (TLP) of a floating wind turbine. However, there has been little research on the arrangement of the TLP's internal structure. In this study, a TLP model and a 5-MW wind turbine model as proposed by the Minstitute of Technology and the National Renewable Energy Laboratory have been adopted, respectively, to comprehensively analyze wind effects and wave and current combinations. The external additional coupling loads on the TLP and the effects of the loads on variables of the internal structure have been calculated. The study investigates preliminary layout parameters-namely, the thickness of the tension leg body, the contact mode of the top tower on the tension leg, the internal stiffening arrangement, and the formation of the spoke structure-and conducts sensitivity analyses of the TLP internal structure. Stress is found to be at a maximum at the top of the tension leg structure and the maximum stress has low sensitivity to the load application point. Different methods of reducing maximum stress have been researched and analyzed, and the effectiveness of these methods is analyzed. Filling of the spoke structure with concrete is discussed. Since the TLP structure for offshore wind power is still under early exploration, arrangements and the configuration of the internal structure, exploration and improvements are ongoing. With regard to its research and analysis process, this paper aims to guide future applications of tension leg structures for floating wind turbine.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.3 no.1
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• pp.83-95
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• 1999

Wavelet transform has localization for time or frequency. It is useful to analyze a nonstationary signal. Basic function on wavelet transform is generated dilating and translating the original wavelet(mother wavelet). In this paper, time-frequency analysis method using linear combination wavelet transform is proposed. And it is applied to diagnostic monitoring system using the proposed linear combination wavelet transform. The stationary and nonstationary signal is used linear chirp signal, fan noise signal, a sinusoid signal from revolution body, electronic signal. Transform applied to signal analysis use fast Fourier transform (FFT), Daubechies, Haar and proposed linear combination method. The result of time-frequency analysis using linear combination wavelet transform is suited for portraying nonstationary time signal as well as stationary signal. Also the diagnostic monitoring system carry out the effective the signal analysis.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2012.05a
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• pp.219-224
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• 2012

In this work, a steady-state performance modeling and off-design performance analysis of the 2-spool separate jet turbofan engine named BR715-56 which is a power plant for the narrow body commercial aircraft is carried out for engine performance behaviors investigation and condition monitoring using a commercial code MATLAB/SIMULINK. Firstly, the engine component maps of fan, high pressure compressor, high pressure turbine and low pressure turbine are generated from similar component maps using the scaling method, and then the off-design performance simulation model is constructed by the mass flow matching and the work matching between components. The model is developed using SIMULINK, which has advantages of easy steady-stare and dynamic modelling and user friendly interface function. It is found that the off-design performance analysis results using the proposed model are well agreed with the performance analysis results by GASTURB at various operating conditions.

• Journal of Bio-Environment Control
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• v.32 no.3
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• pp.197-204
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• 2023

Heat stress causes a decrease in immunity and disease occurrence in livestock, increasing mortality and impairing productivity. In particular, chickens are very vulnerable to high temperatures compared to other livestock species because their entire body is covered with feathers and sweat glands are not developed. Currently, air conditioning systems are essential in broiler houses to prevent high-air temperature damage to broilers, but conventional cooling facilities are greatly affected by the external environment, so there are limits to their use. In this study, to propose a cooling method, thermal insulation paint and a heat pump were apply in the broiler houses to evaluate the temperature reduction effect. The heat pump experiment was to analyze the cooling effect according to the change in ventilation rate and propose an appropriate. As a result of the experiment, the heat-insulating paint reduced the temperature of the broiler houses by maximum 1-2℃, and in the broiler houses where the heat pump was operated, the temperature decrease was the largest when the ventilation rate was the lowest. When the air temperature in the house is similar to or lower than the outside air temperature, it is considered to be most effective to use a heat pump while maintaining only the minimum ventilation rate.

• Asian-Australasian Journal of Animal Sciences
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• v.30 no.4
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• pp.554-561
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• 2017

Objective: This experiment was conducted as a $3{\times}2{\times}2$ factorial design to examine the effects of particle size (mean particle size of 331, 640, or $862{\mu}m$), evaluation method (direct vs indirect method) and adaptation duration (7 or 26 days) on the energy content and the apparent total tract digestibility (ATTD) of various chemical components in wheat when fed to finishing pigs. Methods: Forty-two barrows ($Duroc{\times}Landrace{\times}Yorkshire$) with an initial body weight of $63.0{\pm}0.8kg$ were individually placed in metabolic cages and randomly allotted to 1 of 7 diets with 6 pigs fed each diet. For the indirect method, the pigs were fed either a corn-soybean meal based basal diet or diets in which 38.94% of the basal diet was substituted by wheat of the different particle sizes. In the direct method, the diets contained 97.34% wheat with the different particle sizes. For both the direct and indirect methods, the pigs were adapted to their diets for either 7 or 26 days. Results: A reduction in particle size linearly increased the digestible energy (DE) and metabolizable energy (ME) contents as well as the ATTD of gross energy, crude protein, organic matter, ether extract (EE) and acid detergent fiber (ADF) (p<0.05), and had a trend to increase the ATTD of dry matter of wheat (p = 0.084). The DE, ME contents, and ATTD of gross energy, crude protein, dry matter and organic matter were higher (p<0.05) when determined by the direct method, but the ATTD of ADF, EE, and neutral detergent fiber were higher when determined by the indirect method (p<0.05). Prolongation of the adaption duration decreased the ATTD of neutral detergent fiber (p<0.05) and had a trend to increase the ATTD of EE (p = 0.061). There were no interactions between particle size and the duration of the adaptation duration. The ATTD of EE in wheat was influenced by a trend of interaction between method and adaptation duration (p = 0.074). The ATTD of ADF and EE in wheat was influenced by an interaction between evaluation method and wheat particle size such that there were linear equations (p<0.01) about ATTD of ADF and EE when determined by the direct method but quadratic equations (p = 0.073 and p = 0.088, respectively) about ATTD of ADF and EE when determined by the indirect method. Conclusion: Decreasing particle size can improve the DE and ME contents of wheat; both of the direct and indirect methods of evaluation are suitable for evaluating the DE and ME contents of wheat with different particle sizes; and an adaptation duration of 7 d is sufficient to evaluate DE and ME contents of wheat in finishing pigs.

• Animal Bioscience
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• v.37 no.7
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• pp.1213-1224
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• 2024

Objective: Enterotypes (ETs) are the clustering of gut microbial community structures, which could serve as indicators of growth performance and carcass traits. However, ETs have been sparsely investigated in waterfowl. The objective of this study was to identify the ileal ETs and explore the correlation of the ETs with growth performance and carcass traits in Muscovy ducks. Methods: A total of 200 Muscovy ducks were randomly selected from a population of 5,000 ducks at 70-day old, weighed and slaughtered. The growth performance and carcass traits, including body weight, dressed weight and evidenced weight, dressed percentage, percentage of apparent yield, breast muscle weight, leg muscle weight, percentage of leg muscle and percentage of breast muscle, were determined. The contents of ileum were collected for the isolation of DNA and 16S rRNA gene sequencing. The ETs were identified based on the 16S rRNA gene sequencing data and the correlation of the ETs with growth performance and carcass traits was performed by Spearman correlation analysis. Results: Three ETs (ET1, ET2, and ET3) were observed in the ileal microbiota of Muscovy ducks with significant differences in number of features and α-diversity among these ETs (p<0.05). Streptococcus, Candida Arthritis, and Bacteroidetes were the presentative genus in ET1 to ET3, respectively. Correlation analysis revealed that Lactococcus and Bradyrhizobium were significantly correlated with percentage of eviscerated yield and leg muscle weight (p<0.05) while ETs were found to have a close association with percentage of eviscerated yield, leg muscle weight, and percentage of leg muscle in Muscovy ducks. However, the growth performance of ducks with different ETs did not show significant difference (p>0.05). Lactococcus were found to be significantly correlated with leg muscle weight, dressed weight, and percentage of eviscerated yield. Conclusion: Our findings revealed a substantial variation in carcass traits associated with ETs in Muscovy ducks. It is implied that ETs might have the potential to serve as a valuable biomarker for assessing duck carcass traits. It would provide novel insights into the interaction of gut microbiota with growth performance and carcass traits of ducks.

• Asian-Australasian Journal of Animal Sciences
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• v.30 no.1
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• pp.57-63
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• 2017

Objective: Two experiments were conducted to determine the effects of adding exogenous phytase and xylanase, individually or in combination, as well as pelleting on nutrient digestibility, available energy content of wheat and the performance of growing pigs fed wheat-based diets. Methods: In Experiment 1, forty-eight barrows with an initial body weight of $35.9{\pm}0.6kg$ were randomly assigned to a $2{\times}4$ factorial experiment with the main effects being feed form (pellet vs meal) and enzyme supplementation (none, 10,000 U/kg phytase, 4,000 U/kg xylanase or 10,000 U/kg phytase plus 4,000 U/kg xylanase). The basal diet contained 97.8% wheat. Pigs were placed in metabolic cages for a 7-d adaptation period followed by a 5-d total collection of feces and urine. Nutrient digestibility and available energy content were determined. Experiment 2 was conducted to evaluate the effects of pelleting and enzymes on performance of wheat for growing pigs. In this experiment, 180 growing pigs ($35.2{\pm}9.0kg\;BW$) were allocated to 1 of 6 treatments according to a $2{\times}3$ factorial treatment arrangement with the main effects being feed form (meal vs pellet) and enzyme supplementation (0, 2,500 or 5,000 U/kg xylanase). Results: In Experiment 1, there were no interactions between feed form and enzyme supplementation. Pelleting reduced the digestibility of acid detergent fiber (ADF) by 6.4 percentage units (p<0.01), increased the digestibility of energy by 0.6 percentage units (p<0.05), and tended to improve the digestibility of crude protein by 0.5 percentage units (p = 0.07) compared with diets in mash form. The addition of phytase improved the digestibility of phosphorus (p<0.01) and calcium (p<0.01) by 6.9 and 7.6 percentage units respectively compared with control group. Adding xylanase tended to increase the digestibility of crude protein by 1.0 percentage units (p = 0.09) and increased the digestibility of neutral detergent fiber (NDF) (p<0.01) compared with control group. Supplementation of the xylanase-phytase combination improved the digestibility of phosphorus (p<0.01) but impaired NDF digestibility (p<0.05) compared with adding xylanase alone. In Experiment 2, adding xylanase increased average daily gain (p<0.01) and linearly improved the feed:gain ratio (p<0.01) compared with control group. Conclusion: Pelleting improved energy digestibility but decreased ADF digestibility. Adding xylanase increased crude protein digestibility and pig performance. Phytase increased the apparent total tract digestibility of phosphorus and calcium. The combination of phytase-xylanase supplementation impaired the effects of xylanase on NDF digestibility.

• Parasites, Hosts and Diseases
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• v.58 no.2
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• pp.153-159
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• 2020

The chigger mite Leptotrombidium sialkotense is one of the 6 main vectors of scrub typhus in China. Before present study, L. sialkotense was found in some parts of Hunan province, China with a narrow geographical distribution. During field investigation 2016-2017, we found L. sialkotense in Jingha, southern Yunnan, China. Of 15 small mammal host species, L. sialkotense were collected from 6 species of the hosts. Rattus brunneusculus was a dominant host of L. sialkotense, from which 98.3% of the mites were collected. The chigger mite showed a relatively high infestation prevalence (P_M =11.7%) and mean abundance (MA=0.5) in comparison with the rest 5 host species. These results reveal a certain host specificity of L. sialkotense to a rat R. brunneusculus. The mite L. sialkotense showed an aggregated distribution on the host (P<0.05). A positive correlation observed between L. sialkotense and the body length of hosts. There was a positive interspecific association between L. sialkotense and 2 other dominant vectors, L. deliense and L. scutellare.

• Parasites, Hosts and Diseases
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• v.32 no.3
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• pp.143-148
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• 1994

The metacercanae of the genus Stictodora encysted in gobies, Acnnthogobiln Snuimanw, purchased from a local market of Haenarn-gun, Chollanam-do, were identified as those of S. fuscotum A total of 1,437 metacercariae were collected from 30 gobies and sonle of them were orally fed to cats in order to obtain the adult worms. The metacercariae were 0.194-0.301 mm by 0.168-0.270 mm In size, yellowish brown, round to elliptical, and with a thin and transparent cyst wall. The excysted larvae were 0.280-0.423 mm long and 0.150-0.184 mm wide, beset with numerous tegumental spines on the anterior half of the body, and equipped 10 a characteristic ventrogenital sac. Total 21 adult worms were recovered from 2 cats 7 days after infection. The adult worms were small, leaf-like, 0.514-0.918 mm long and 0.235-0.377 mm wide. The ventrogenital sac was elliptical and its gonotyl was armed with 13-18 spines which were radially arranged and appeared as fan-shape. It has been confirmed that A. flavimanus is a second interinedlate host of 5. Juscatum In Korea.