• Journal of the Korean Geotechnical Society
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• v.37 no.5
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• pp.5-17
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• 2021

In this study, the shear behavior between pile-sandy soil interface was quantified based on series of rigorous ring shear test results. Ring shearing test was carried out to observe the shear behavior prior to failure and behavior at residual state between most commonly used pile materials - steel and concrete - and Jumunjin sand. The test was set to clarify the shear behavior under various confinement conditions and soil densities. The test results were converted in to representative friction angles for various test materials. Additional numerical analysis was executed to validate the accuracy of the test results. Based on the test results and the numerical validation, it was found that due to the dilative and contractive nature of sand, its interface behavior can be categorized in to two different types : soils with higher densities tend to show peak shear stress and moves on to residual state, while on the other hand, soils with lower densities tend to show bilinear load-transfer curves along the interface. However, the relative density and the confining stress was found to affect the friction angle only in the small train range, and converges as it progresses to large deformation. This study established a large deformation analysis method which can successfully simulate and predict the large deformation behavior such as ring shear tests. Moreover, the friction angle derived from the ring shear test result and verified by numerical analysis can be applied to numerical analysis and actual design of various pile foundations.

• Animal Bioscience
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• v.37 no.3
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• pp.500-508
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• 2024

Objective: Due to current selection practices for increased egg production and peak persistency, the production profile, age at maturity, and body weight criteria for commercial layers are constantly changing. Body weight and age at the time of photostimulation will thus always be the factors that need to be adequately addressed among various production systems. The current study was carried out to determine the effects of pullets' body weight (low, medium, and heavy) on their performance, welfare, physiological response, and hormonal profile. Methods: With regard to live weight, 150 16-week-old pullets were divided into three groups using a completely randomized design (CRD) and held until the 50th week. One-way analysis of variance was used to evaluate the data under the CRD, and the least significant difference test was used to distinguish between treatment means. Results: In comparison to the medium and light birds, the heavy birds had higher body weight at maturity, an earlier age at maturity, and higher egg weight, eggshell weight, eggshell thickness, egg yolk index, breaking strength, egg surface area, egg shape index, egg volume, and hormonal profile except corticosterone. However, the medium and light birds had lower feed consumption rates per dozen eggs and per kilogram of egg mass than the heavy birds. Light birds showed greater body weight gain, egg production, and egg specific gravity than the other categories. At 20 weeks of age, physiological response, welfare aspects, and catalase were non-significant; however, at 50 weeks of age, all these factors-aside from catalase-were extremely significant. Conclusion: The findings of this study indicate that layers can function at lower body weights during photostimulation; hence, dietary regimens that result in lighter pullets may be preferable. Additionally, the welfare of the birds was not compromised by the lighter weight group.

• Journal of the Korean earth science society
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• v.23 no.4
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• pp.357-368
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• 2002

In this study we have tried to explain the barrel-shaped morphology for young supernova remnants considering the dynamical effects of the ejecta. We consider the magnetic field amplification resulting from the Rayleigh-Taylor instability near the contact discontinuity. We can generate the synthetic radio image assuming the cosmic-ray pressure and calculate the azimuthal intensity ratio (A) to enable a quantitative comparison with observations. The postshock magnetic field are amplified by shearing, stretching, and compressing at the R-T finger boundary. The evolution of the instability strongly depends on the deceleration of the ejecta and the evolutionary stage of the remnant. the strength of the magnetic field increases in the initial phase and decreases after the reverse shock passes the constant density region of the ejecta. However, some memory of the earlier phases of amplification is retained in the interior even when the outer regions turn into a blast wave. The ratio of the averaged magnetic field strength at the equator to the one at the pole in the turbulent region can amount to 7.5 at the peak. The magnetic field amplification can make the large azimuthal intensity ratio (A=15). The magnitude of the amplification is sensitive to numerical resolution. This mens the magnetic field amplification can explain the barrel-shaped morphology of young supernova remnant without the dependence of the efficiency of the cosmic-ray acceleration on the magnetic field configuration. In order for this mechanism to be effective, the surrounding magnetic field must be well-ordered. The small number of barrel-shaped remnants may indicate that this condition rarely occurs.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.37 no.3
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• pp.196-213
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• 2001

A split beam ultrasonic transducer operating at a frequency of 70 kHz to use in the fish sizing echo sounder was developed and the acoustic radiation characteristics were experimentally analyzed. The amplitude shading method utilizing the properties of the Chebyshev polynomials was used to obtain side lobe levels below -20 dB and to optimize the relationship between main beam width and side lobe level of the transducer, and the amplitude shading coefficient to each of the elements was achieved by changing the amplitude contribution of elements with 4 weighting transformers embodied in the planar array transducer assembly. The planar array split beam transducer assembly was composed of 36 piezoelectric ceramics (NEPEC N-21, Tokin) of rod type of 10 mm in diameter and 18.7 mm in length of 70 kHz arranged in the rectangular configuration, and the 4 electrical inputs were supplied to the beamformer. A series of impedance measurements were conducted to check the uniformity of the individual quadrants, and also in the configurations of reception and transmission, resonant frequency, and the transmitting and receiving characteristics were measured in the water tank and analyzed, respectively. The results obtained are summarized as follows : 1. Average resonant and antiresonant frequencies of electrical impedance for four quadrants of the split beam transducer in water were 69.8 kHz and 83.0 kHz, respectively. Average electrical impedance for each individual transducer quadrant was 49.2$\Omega$ at resonant frequency and 704.7$\Omega$ at antiresonant frequency. 2. The resonance peak in the transmitting voltage response (TVR) for four quadrants of the split beam transducer was observed all at 70.0 kHz and the value of TVR was all about 165.5 dB re 1 $\mu$Pa/V at 1 m at 70.0 kHz with bandwidth of 10.0 kHz between -3 dB down points. The resonance peak in the receiving sensitivity (SRT) for four combined quadrants (quad LU+LL, quad RU+RL, quad LU+RU, quad LL+RL) of the split beam transducer was observed all at 75.0 kHz and the value of SRT was all about -177.7 dB re 1 V/$\mu$Pa at 75.0 kHz with bandwidth of 10.0 kHz between -3 dB down points. The sum beam transmitting voltage response and receiving senstivity was 175.0 dB re 1$\mu$Pa/V at 1 m at 75.0 kHz with bandwidth of 10.0 kHz, respectively. 3. The sum beam of split beam transducer was approximately circular with a half beam angle of $9.0^\circ$ at -3 dB points all in both axis of the horizontal plane and the vertical plane. The first measured side lobe levels for the sum beam of split beam transducer were -19.7 dB at $22^\circ$ and -19.4 dB at $-26^\circ$ in the horizontal plane, respectively and -20.1 dB at $22^\circ$ and -22.0 dB at $-26^\circ$ in the vertical plane, respectively. 4. The developed split beam transducer was tested to estimate the angular position of the target in the beam through split beam phase measurements, and the beam pattern loss for target strength corrections was measured and analyzed.

• Korean Journal of Food Science and Technology
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• v.29 no.1
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• pp.1-8
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• 1997

A complement system-activating (anti-complementary) polysaccharide was purified from the hot water extract of young stems of Cinnamomum cassia Blume. Crude polysaccharide fraction (CC-1) was prepared from the hot water extract of the young stems followed by methanol-reflux, precipitation with ethanol, dialysis, and lyophilization. The anti-complementary activity of CC-1 was decreased greatly by periodate oxidation, but was not changed by pronase digestion. These suggest that carbohydrate moiety may be related to the activation of complement system. According to its ionic strength CC-1 was fractionated first using cetavlon to give 4 fractions, CC-2, 3, 4 and 5. Among them CC-2 fraction was found to retain the highest activity and yield. CC-2 was separated to an unabsorbed neutral sugar portion (CC-2-I) and seven absorbed acidic sugar fractions $(CC-2-II{\rightarrow}CC-2-VIII)$ on DEAE-Toyopearl 650C (Cl-). CC-2-III showing higher anti-complementary activity and yield than those of other fractions, was further purified on the gel permeation of Sephadex G-100 and Sepharose CL-6B to CC-2-IIIa-3. CC-2-IIIa-3 was determined to have a homogeneity hy GPC (Sepharose CL-6B) and HPLC. Gel chromatography using standard dextrans gave a value of $2.4{\times}10^5$ for the molecular weight. The purified polysaccharide, CC-2-IIIa-3 consisted of arabinose, xylose, glucose, galactose, galacturonic acid and glucuronic acid in a molar ratio of 5.56 : 3.77 : 1.87 : 1.00 : 5.12 : 3.13 and contained no nitrogen.

• Korean Journal of Food Science and Technology
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• v.39 no.5
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• pp.534-540
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• 2007

In this study, waxy rice starch was chemically modified using phosphorous oxychloride ($POCl_3$, 0.002-0.008%). Then the physicochemical properties of resulting cross-linked waxy rice starches were investigated in order to reduce the steeping time of Yukwa (a Korean oil-puffed rice snack) processing. The swelling powers of the cross-linked waxy rice starch samples were higher than the native waxy rice starch at temperatures above $60^{\circ}C$, and their increases were proportional to the $POCl_3$, concentration. The solubility of the cross-linked waxy rice starch was lower (1.6-3.4%) than the native waxy rice starch (2.7-6.1%). However, the moisture sorption isotherm of the cross-linked waxy rice starch was not significantly different from the native waxy rice starch. The rapid visco analyze. (RVA) pasting temperatures $(65.4-67^{\circ}C)$ of the cross-linked waxy rice starch were lower than those of the native starch $(67^{\circ}C)$. The RVA peak viscosities (287-337 RVU) of the cross-linked waxy rice starch were higher than that of native starch (179 rapid visco units (RVU)), and increased with increasing $POCl_3$ concentration. For the differential scornning calorimeter thermal characteristics, although Tc shifted toward higher temperatures with cross-linking, the To, Tp, and amylopectiin melting enthalpy of the cross-linked waxy rice starch showed no differences compared to the native waxy rice starch. The X-ray diffraction patterns of both the native and cross-linked waxy rice starches showed typical A-type crystal patterns, suggesting that cross-linking mainly occurs in the amorphous regions of starch granules. Therefore, the cross-linking reaction did not change the crystalline region, but altered the amorphous region of the waxy rice starch molecules, resulting in changes of solubility and RVA pasting properties in the cross-linked waxy rice starch. In summary, since cross-linked waxy rice starch has a high puffing efficiency and no browning reaction, it may be applicable for Yukwa processing without a long steeping process.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.30 no.6
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• pp.465-473
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• 2004

Purpose : The essential triad for nerve regeneration is nerve conduit, supporting cell and neurotrophic factor. In order to improve the peripheral nerve regeneration, we used polyglycolic acid(PGA) tube and brain-derived neurotrophic factor(BDNF) gene transfected Schwann cells in sciatic nerve defects of SD rat. Materials and methods : Nerve conduits were made with PGA sheet and outer surface was coated with poly(lactic-co-glycolic acid) for mechanical strength and control the resorption rate. The diameter of conduit was 1.8mm and the length was 17mm Schwann cells were harvested from dorsal root ganglion(DRG) of SD rat aged 1 day. Schwann cells were cultured on the PGA sheet to test the biocompatibility adhesion of Schwann cell. Human BDNF gene was obtained from cDNA library and amplified using PCR. BDNF gene was inserted into E1 deleted region of adenovirus shuttle vector, pAACCMVpARS. BDNF-adenovirus was multiplied in 293 cells and purified. The BDNF-Adenovirus was then infected to the cultured Schwann cells. Left sciatic nerve of SD rat (250g weighing) was exposed and 14mm defects were made. After bridging the defect with PGA conduit, culture medium(MEM), Schwann cells or BDNF-Adenovirus infected Schwann cells were injected into the lumen of conduit, respectively. 12 weeks after operation, gait analysis for sciatic function index, electrophysiology and histomorphometry was performed. Results : Cultured Schwann cells were well adhered to PGA sheet. Sciatic index of BDNF transfected group was $-53.66{\pm}13.43$ which was the best among three groups. The threshold of compound action potential was between 800 to $1000{\mu}A$ in experimental groups which is about 10 times higher than normal sciatic nerve. Conduction velocity and peak voltage of action potential of BDNF group was the highest among experimental groups. The myelin thickness and axonal density of BDNF group was significantly greater than the other groups. Conclusion : BDNF gene transfected Schwann cells could regenerate the sciatic nerve gap(14mm) of rat successfully.

• Korean Journal of Poultry Science
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• v.33 no.3
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• pp.225-231
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• 2006

To investigate the effect of feeding rare earth (RE) on the performance of breeder hens a feeding trial with sixteen thousands of 158 day old Ross broiler breeder hens was conducted for thirty weeks. A mixture of RE- chlorides containing mainly La, Ce, and Pr was mixed into corn-soy based diet at two levels, 300 and 600 mg/kg, All the hens were housed in flat layer houses and the ratio of male to female was maintained at one to ten. Dietary supplementation of the of RE at a level of 300 mg/kg made the hens reach egg production peak higher by about 6% and earlier by about two weeks. As a result, it made higher hatchable egg production by 3.5%. It also reduced dramatically the mortality of both male and female breeders(P<0.05). Egg weight was slightly increased but egg qualify was not much influenced by dietary supplementation of RE. Egg albumin hight and Haugh unit were significantly improved while egg shell thickness, egg breaking strength and yolk color were similar to those of the control. Experimental results appeared to show a good possibility that egg fertility and hatchability were improved by feeding RE. Dietary supplementation of RE at a level of 300 mg/kg should be acceptable but not the 600 mg/kg level for breeder hens. Further studies on the effect of RE on egg fertility and hatchability appears to be necessary.

• Journal of radiological science and technology
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• v.26 no.2
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• pp.57-61
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• 2003

The purpose of this study is to compare both 1.5T and 4.7T in Praietal White matter material Phantom using the same methodology at both field strengths. Data at both field strengths are compared in terms of $T_2$ relaxation times, line widths and SNRs MR imaging and $^1H$ MR spectroscopy were performed on GE 1.5T SIGNA system and Broker Biospec 4.7T/30 MRI/MRS system. After phantom axial scan $^1H$ MRS was obtained from T2 weighted image by 3-dimensional localization technique(PRESS : Point RE solved spectroscopy Sequence) this phantom is composed of an aqueous solution 36.7 mmol/L of NAA, 25.0 mmol/L of Cr, 6.3 mmol/L of choline chloride, 30.0 mmol/L or Glu, and 22.5 mmol/L of MI(adjusted to a pH of 7,15 in a phosphate buffet). Data processed using software developed inhouse. At 1.5T, T2 relaxation times for Cho, Cr, and NAA were $0.41{\pm}0.07,\;0.26{\pm}0.04,\;0.46{\pm}0.07$ while at 4.7T they were $0.17{\pm}0.03,\;0.14{\pm}0.05,\;0.20{\pm}0.03$ respectively. At 1.5T, line widths for water, Cho, Cr and NAA were $2.9{\pm}0.7,\;1.6{\pm}0.7,\;1.7{\pm}0.8,\;2.2{\pm}0.02Hz$ while at 4.7T they were $5.2{\pm}1.1,\;4.6{\pm}1.9,\;4.01{\pm}1.8,\;4.8{\pm}1.9Hz$ respectively. It can be seen that $T_2$ relaxation times were significantly shorter at 4.7 compared to 1.5T and that the line widths were also broader. The average SNRs for NAA for subjects at short and long TEs were $23.5{\pm}11.3$ at TE=20 msec ; $15.4{\pm}7.7$ at TE=272 msec at 1.5T and $40{\pm}8.3$ and $17{\pm}3.5$ respectively at 4.7T higher field strength is superior because of improved sensitivity and chemical shift dispersion. However these improvements are partially offset by increased line widths and decrease $T_2$ relaxation times, which act to reduce both sensitivity and resolution. In our experiments with the equipment available to us, 4.7T proton spectra at short TEs exhibit moderately improved sensitivity compared to 1.5T.

• Journal of the Korean Society of Food Science and Nutrition
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• v.42 no.6
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• pp.877-884
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• 2013

This study investigated the optimal composition of sugar and artificial sweeteners in oatmeal cookies. Modified cookies were examined for their quality characteristics and glycemic index in humans. Oatmeal cookies with various amounts of sugar (20, 30, or 40%) were made to the equivalent sweetness of 100% sugar cookies (the control) with sucralose and stevioside. The density and acidity of cookie dough were not significantly different between the different cookie groups. However, baking loss and the spread index were significantly lower in the 100% sugar cookie group compared to cookies supplemented with artificial sweeteners. The color lightness (L value) and redness (a value) were highest in 30% and 100% sugar cookies, respectively. The strength of the cookies was negatively correlated with sugar content. In sensory evaluations, scores for taste, color and texture were higher in 30% and 40% sugar cookies, respectively, but the overall preference was higher in 30% sugar cookies. We therefore tested 30% and 100% sugar cookies for their glycemic index in college students. After overnight-fasted students consumed either 30% or 100% sugar cookies (containing 50 g of carbohydrate in dough weight), blood glucose levels increased 27.8 and 15.7 mg/dL, respectively, at 1 hour from the baseline. However, at 2 hours from the baseline, students who consumed 100% sugar cookies had a remarkably lowered blood glucose levels. Students who consumed 30% sugar cookies did not have as much of a change in blood glucose levels. In conclusion, 30% sugar oatmeal cookies made with sucralose and stevioside can be used to make a low-sugar cookie with a low glycemic index.