• Ocean and Polar Research
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• 제24권4호
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• pp.483-490
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• 2002

Detailed investigations on both submarine and subaerial volcaniclastic deposits around Dokdo were carried out to identify geomorphologic characteristics, stratigraphy, and associated depositional processes of Dokdo caldera. Dokdo volcano has a gently sloping summit (about 11km in diameter) and relatively steep slope (basal diameter is about 20-25 km) rising above sea level at about 2,270m. We found ragged, elliptical-form of Dokdo caldera with a diameter of about 2km estimated by Chirp (3-11 kHz) sub-bottom profile data and side scan sonar data for the central summit area of Dokdo volcano. We interpreted that the volcaniclastic deposits of Dokdo unconformably consist of the Seodo (west islet) and the Dongdo(east islet) formations based on internal structure, constituent mineral composition, and bedding morphology. The Seodo Formation mainly consisted of massive or inversely graded trachytic breccias (Unit S-I), overlain by fine-grained tuff (Unit S-II), which is probably supplied by mass-wasting processes resulting from Dokdo caldera collapse. The Dongdo Formation consists of alternated units of stratified lapilli tuff and inversely graded basaltic breccia (Unit D-I, Unit D-III, and Unit D-V), and massive to undulatory-bedded basaltic tuff breccias (Unit D-II and Unit D-IV) formed by a repetitive pyroclastic surge and reworking processes. Although, two islets of Dokdo are geographically near each other, they have different formations reflecting their different depositional processes and eruptive stages.

• Structural Engineering and Mechanics
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• 제85권1호
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• pp.105-118
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• 2023

The present work is an attempt to develop a simple and accurate finite element formulation for the assessment of thermal shock/thermally induced vibrations in pretwisted and tapered functionally graded material thin (FGM) blades obtained from Voigt and local representative volume elements (LRVE) homogenization models, based on neutral surface approach. The neutral surface of the FGM blade does not coincide with its mid-surface. A finite element model (FEM) is developed using first-order shear deformation theory (FSDT) and the FGM turbine blade is modelled according to the shallow shell theory. The top and the bottom layers of the FGM blade are made of pure ceramic and pure metal, respectively and temperature-dependent material properties are functionally graded in the thickness direction, the position of the neutral surface also depends on the temperature. The material properties are estimated according to two different homogenization models viz., Voigt or LRVE. The top layer of the FGM blade is subjected to high temperature and the bottom surface is either thermally insulated or kept at room temperature. The solution of the nonlinear profile of the temperature in the thickness direction is obtained from the Fourier law of heat conduction in the unsteady state. The results obtained from the present FEM are compared with the benchmark examples. Next, the effect of angle of twist, intensity of thermal shock, variable chord and span and volume fraction index on the transient response due to thermal shock obtained from the two homogenization models viz., Voigt and LRVE scheme is investigated. It is shown that there can be a significant difference in the transient response calculated by the two homogenization models for a particular set of material and geometric parameters.

• 한국레이저가공학회지
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• 제17권2호
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• pp.19-25
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• 2014

Optical embedded diffraction gratings with the bulk modification in BK-7 glass plates excited by tightly focused high-intensity femtosecond (130fs) Ti: sapphire laser (peak wavelength = 790nm) were demonstrated. The structural modifications with diameters ranging from 400nm to $4{\mu}m$ were photo-induced after plasma formation occurred upon irradiation with peak intensities of more than $1{\times}1013W/cm^2$. The graded refractive index profile was fabricated to be a symmetric around from the center of the point at which low-density plasma occurred. The maximum refractive index change was estimated to be $1.5{\times}10^{-2}$. The two optical embedded gratings in BK-7 glass plate were demonstrated with refractive index modification induced by the scanning of low-density plasma formation.

• Asian-Australasian Journal of Animal Sciences
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• 제21권3호
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• pp.426-433
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• 2008

Heat stress is major welfare problem in the poultry industry. Huge economic losses occur every year because of mortality and decreased production due to high environmental temperatures. This experiment was conducted to determine the effects of level of inclusion of ascorbic acid supplementation to the diet on performance, carcass composition and bone characteristics of male turkeys during high summer temperature. A total of 120 day-old turkey chicks were wing banded at hatch and randomly distributed into 3 treatment groups. Three diets were formulated to provide a similar nutrient profile with the exception of using three graded levels of ascorbic acid, namely 0, 150 and 300 mg/kg of the diet. The experimental diets were used from 0 to 18 weeks of age. Body weights, feed intake and feed conversion ratio, slaughter weight, carcass yield, portions, composition and thigh and breast pigmentation of the turkeys were not affected by ascorbic acid (p>0.05). Also, shank and tibia bone characteristics were not affected by ascorbic acid (p>0.05).

• 한국세라믹학회지
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• 제21권1호
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• pp.33-40
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• 1984

To find out the optimum heating profile for the nitridation of compacts of graded silicon grains (max 53$mu extrm{m}$) two batches with the addition of MgO and $Mg(NO_3)_3$$cdot$$6H_2O$ to silicon particles were isostatically pressed into compacts. They were nitrided under some different nitriding schedules. The properties such as bulk densitis microstructures and formed phases were measured and observed. The following results were obtained ; 1) About 10% unreacted silicon remained in specimen which was nitrided at 1, 350$^{\circ}C$ for 240hrs. 2) One of the step-heating processes 1, 150$^{\circ}C$-1, 390$^{\circ}C$ for 65hrs are then $1, 390^{\circ}C$for 50hrs was the low temperature but with that at high temperature. 3) High pressure(10.5kgf/$cm^2$) of nitrogen at 1, 390$^{\circ}C$ accelerated the $\alpha$$ ightarrow$$\beta$ transformation of silicon nitride. 4) Magnesium nitrate was superior to magnesium oxide in the role of nitriding aid and the formation of uniform microstructures.

• Asian-Australasian Journal of Animal Sciences
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• 제16권12호
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• pp.1777-1781
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• 2003

The lysine requirements of juvenile yellowtail flounder (Pleuronectes ferrugineus) having 19.5 g initial body weight were estimated by feeding six practical-type diets containing graded levels of lysine (1.21 to 2.69% of dry diet). Dietary amino acid profile simulated that of whole body of yellowtail flounder. Most of amino acids in the diets were provided by corn gluten meal, herring meal and gelatin. Protein efficiency ratio (PER) improved significantly until lysine level increased up to 2.1% (4.3% of protein). Same trend was observed in feed:gain ratio (FGR) which maintained constant in fish groups fed diets containing lysine above 2.1%. The highest nitrogen gain (0.34 g/fish) in whole body was found in fish fed 2.1% lysine, though the value was not different from those of fish fed above the level of lysine. Fish fed 2.1% lysine also showed the best nitrogen retention efficiency of 24.6%. The broken-line analysis of protein efficiency ratio and body nitrogen gain against dietary lysine level yielded an estimated lysine requirement of 2.2% (4.5% of protein) and 2.3% (4.7% of protein), respectively.

• 한국레이저가공학회지
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• 제14권1호
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• pp.1-5
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• 2011

Photo-induced gratings m flexible PDMS (polydimethly siloxane) film are directly written by a high-intensity femtosecond (130fs) Ti: Sapphire laser (${\lambda}_p$ = 800nm). The refractive index modifications with $4\;{\mu}m$ diameters were photo-induced after the femtosecond irradiation with peak intensities of more than $1{\times}10^{11}W/cm^2$. The graded refractive index profile was fabricated to be a symmetric around the center of the point at which femtosecond laser by controlling both laser power and focused depth. The change on refractive index in the laser-modified regions was estimated to be approximately $10^{-3}$. The internal flexible symmetric diffraction gratings in PDMS film was successfully fabricated using a femtosecond laser.

• Asian-Australasian Journal of Animal Sciences
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• 제32권10호
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• pp.1565-1572
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• 2019

Objective: This study was aimed to investigate the effects of brewer's yeast hydrolysate (YH) on growth performance, nutrients digestibility, blood profiles and meat quality of growing pigs. Methods: A total of 200 growing pigs ($[Landrace{\times}Yorkshire]{\times}Duroc$) (initial body weight, $25.31{\pm}1.29kg$) were allotted to 5 treatments as follow: CON, basic diet; and YH treatment, CON+0.05%, 0.1%, 0.5%, and 1.0% of YH, respectively. Results: On wk 11, 16 and overall phase, pigs fed YH diet showed a linear improvement in average daily body gain and gain/feed (p<0.05). The pigs that received YH linearly increased the digestibility of dry matter, nitrogen, and energy on wk 11 and 16. The concentration of serum urea nitrogen was linearly increased in YH treatments on wk 16. However, the carcass weight, back fat and lean muscle percentage of pigs receiving YH had no significant change. Besides, no difference was observed in creatinine and total protein in the blood among treatments. Conclusion: The pigs fed a graded YH diet had improved growth performance and nutrient digestibility, meanwhile, the YH increased the serum urea nitrogen in the growing pigs.

• Steel and Composite Structures
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• 제41권6호
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• pp.787-803
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• 2021

The size-dependent nonlinear thermomechanical vibration analysis of pre- and post-buckled tapered two-directional functionally graded (2D-FG) microbeams is presented in this study. In the context of the modified couple stress theory, the formulations are derived based on the parabolic shear deformation beam theory and von Karman nonlinear strains. Different thermomechanical material properties are assumed to be temperature-dependent and smoothly vary in both length and thickness directions using the power law and the physical neutral axis concept is employed. The nonlinear governing equations are derived using the Hamilton principle and the resulting variable coefficient equations of motion are solved using the differential quadrature method (DQM) and iterative Newton's method for clamped-clamped and simply supported boundary conditions. Comparison studies are presented to validate the derived model and solution procedure. The impacts of induced thermal moments, temperature power index, two gradient indices, nonuniform cross-section, and microstructure length scale parameter on the frequency-temperature configurations are explored for both clamped and simply supported microbeams.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1995년도 추계학술발표회논문집(1)
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• pp.35-40
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• 1995

Considering the higher discharge burnup, lower channel refuelling rate, lower linear element rating(LER), lower coolant void reactivity and axial power shape, CANFLEX-RU fuel bundle is optimized for CANDU-6 by grading the fissile composition in the ring-wise of the bundle and by applying fuel management scheme appropriately. The fissile composition of the fuel bundle is graded as the recovered uranium (0.9 w/o U-235) in the outer and intermediate elements, depleted Uranium (0.2 w/o U-235) in the center element, natural uranium (0.71 w/o U-235) in the inner elements. Enrichment is not required for these fuel. The fissile composition is optimized by lattice calculation and by time-averaged reactor simulation. CANFLEX-RU optimized for CANDU-6 resulted to be the 15% lower channel refuelling rate, acceptable axial power profile and power envelope, 70% higher discharge burnup, 15% lower LER and not increase coolant void reactivity compared with the 37-element natural uranium bundle for CANDU-6.