• Korean Journal of Organic Agriculture
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• v.9 no.2
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• pp.55-67
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• 2001

Exogenous enzymes which, for the purpose of this paper, include phytase, $\beta$-glucanase, pentosanase and $\alpha$-galactosidase, are now extensively used throughout the world as aditives in swine diets. The chemical effects of these enzymes are well understand. However, the manner in which their benefits to the swine are brought about is still under debate. Phytase was to increase the availability of plant phytate phosphorus, which reduces phosphorus pollution and allows reductions in the amount of inorganic phosphate used. Also, enzymes have been discovered which have the potential to break down deleterious compounds commonly found in swine rations such as $\beta$-glucanase contained in barley and oats and the soluble pentosans found in rye and wheat thus increasing the digestibility of these non-starch polysaccharides. Future research in these area will allow for more efficient use of the current enzymes, development of more efficient future products and development of more thermotolerant enzymes.

• The Journal of Engineering Geology
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• v.12 no.1
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• pp.89-93
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• 2002

Seismic geotomography method was performed to verify rock-filled settlement and its stability in No.38+0 profile and No.40+0 profile. The velocity distributions of geotomography method expressed the quantitative value of the ground conditions. The rock-filled layer and in-situ sediments layer are clearly divided on the basis of seismic velocity 2100 m/sec which is derived from the results of seismic geotomography and boring. Current rock-filled settlement conditions are somewhat different from designed settlement estimation line. Seismic geotomography represents current settlement conditions as a quantitative analysis.

• Bulletin of the Korean Space Science Society
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• 2003.10a
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• pp.73-73
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• 2003

인공위성은 발사체에 실려 임무궤도에 도달하는 동안 여러 과정을 겪고 이에 따른 우주 열환경에 노출되게 된다. 본 연구에서는 발사체의 페어링(Fairing)이 열리고 이후 인공위성이 임무궤도에 도달하는 동안까지 인공위성에 대한 열해석을 수치적인 방법을 이용하지 않고 해석해를 이용하여 수행하였다. 일반적으로 발사시 인공위성에 대한 열해석은 수치모델을 개발하여야 하는 시간과 노력이 많이 드는 작업이다. 그러나 수치 모델이 완성되기 전에 주요 부품에 대한 극한 환경에서의 온도 예측이 필요한 경우가 있다. 본 연구는 해석 기법을 이용하여 주요 부품의 온도를 비교적 간단한 방법으로 예측하는 것이다. 이를 위하여 열관련 지배방정식에 여러 가정을 적용하여 지배방정식을 최대한 단순화시켰다. 그 결과, 최종적으로 1차 미분 방정식 형태의 단순화된 지배방정식을 얻게 되었다. 또한 본 연구에서는 여러가지 조건에 대한 연구가 시도하였다. 즉 고려하는 대상의 질량이 일정하게 유지 되는 경우와 일정한 비율로 질량이 감소하는 경우, 인공위성이 최악의 고온환경과 최악의 저온환경에 처한 경우, 그리고 시간에 대한 변수항 때문에 약간의 수치작업이 필요한 경우가 연구되었다. 본 연구에서 제안된 해석해 기법은 적절한 우주 열환경 조건과 결합하게 되면 발사과정에 대한 완전한 수치모델이 완성되기전에 위성체 부품에 대한 열적 안정성을 검토하는데 유용하게 이용될 수 있을 것이다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.12C
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• pp.1280-1287
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• 2006

We propose a modified stochastic gradient-based (MSGB) filter showing that the filter is the solution to an optimization problem. This paper analyzes the properties of the MSGB filter that corresponds to the nonlinear adaptive filter with additional update terms, parameterized by the variable scaling factor. The variably parameterized MSGB filter plays a role iii connecting the fixed parameterized MSGB filter and the null parameterized MSGB filter through variably scaling parameter. The stability regions and misadjustments are shown. A system identification is utilized to perform the computer simulation and demonstrate the improved performance feature of the MSGB filter.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.10
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• pp.178-184
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• 2007

A new adaptive alternating-direction-implicit finite-difference time-domain (ADI-FDTD) method is proposed to obtain isotropic wave propagation for all directional angles. We add the square terms of time-step multiplied by the spatial derivatives of x and y as a perturbed term to the conventional ADI-FDTD and can find the optimization coefficient of square terms of time-step to generate the minimum anisotropy. The new ADI-FDTD is also stable, even when its time-step is greater than the Courant-Friedrich-Levy (CFL) limit. The characteristic equation of the dispersion relation governing the new method is derived and compared with the theoretical and numerical results for the conventional ADI-FDTD and perturbed ADI-FDTD methods.

• The Transactions of the Korean Institute of Power Electronics
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• v.2 no.4
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• pp.36-44
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• 1997

For high performance ac drives, the speed sensorless vector control and the stator flux orientation concept have received increasing attention. This paper describes a speed and flux sensorless vector-controlled induction machine(IM) drive based on the stator flux-oriented control. To improve the accuracy and operating range, the control system employs the previously presented speed and flux estimation methods, and then we present a developed method of estimating the speed of IM. In the proposed method all differential and integral terms have been eliminated by giving a very fast, low-cost, effective and practical alternative to the methods currently available. The effectiveness of the proposed method is verified by simulations and experimental results.

• Journal of the Korean Institute of Intelligent Systems
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• v.8 no.2
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• pp.117-127
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• 1998

Power systems have uncertain dynamics due to a variety of effects such as lightning, severe storms and equipment failures. The variation of the effective reactance of a transmission line due to a fault is an example of uncertainty in power system dynamics. Hence, a robust controller to cope with these uncertainties is needed. Recently, fuzzy controllers are becoming quite popular for robust control due to its potential of dealing with uncertain systems. Thus in this paper we design an adaptive fuzzy controller based on an input-output linearization approach for the transient stabilization and voltage regulation of a power system under a sudden fault. Also this paper proposes a fuzzy system that estimates the upper bound of uncertain term in the system dynamics to guarantee the Lyapunov stability. Simulation results show that good performance is achieved by the proposed controller.

• Clinical and Experimental Pediatrics
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• v.48 no.6
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• pp.669-674
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• 2005

Nephrogenic diabetes insipidus (NDI) is a disorder in which the secretion of antidiuretic hormone is normal, but the response of the renal collecting tubules to vasopressin is impaired. Compared with acquired NDI (a-NDI), which is secondary to chronic bilateral incomplete urinary tract obstruction with hydronephrosis, congenital NDI (c-NDI) is a very rare heritable disorder that usually follows the X- linked recessive pattern. Clinical symptoms of c-NDI can be non specific, and often the disease ultimately results in failure to thrive, or mental retardation. Recently, the diagnosis can be confirmed by direct sequencing analysis of the peripheral blood specimens. The long-term results of treatment for c-NDI are not satisfactory. Reports on the follow up of c-NDI cases are rare and there is no report on the cases treated with combinations of three drugs. We report herein a case of severe c-NDI in an 8 year-old-boy with a severely dysconfigurated urinary tract system. The patient and his mother showed a frameshift mutation on the AVPR2 gene on chromosome Xq28:.847_851delTGCTG (p.C283fsX90). The patient showed normal growth and development by treatment with combinations of hydrochlorothiazide ($65mg/m^2$), amiloride (0.3 mg/kg/d) and indomethacin ($100mg/m^2$), yet after five years he needed adjuvant cystostomy to relieve him from the residual symptoms of urgency with polyuria.

• Journal of the Korean Society of Food Science and Nutrition
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• v.40 no.6
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• pp.903-911
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• 2011

In this study, Bacillus polyfermenticus CJ6 harboring antibacterial activity was isolated from meju. The antibacterial activity of Bacillus polyfermenticus CJ6 was stable in the pH range of 3.0~9.0, but it disappeared after culture at $70^{\circ}C$ for 24 hr. Antibacterial activity was inactivated by proteinase K, protease, and ${\alpha}$-chymotrypsin, indicating its proteinaceous nature. The growth inhibitory effects of B. polyfermenticus CJ6 culture on food-borne pathogens such as Staphylococcus aureus, Salmonella Typhi, Listeria monocytogenes, and Escherichia coli O157:H7 were examined in this study. Approximately 6~6.2 log CFU/mL of each pathogen was co-cultured with B. polyfermenticus CJ6 in a 50 mL culture volume for 24 hr. Growth of S. aureus and L. monocytogenes was completely inhibited after 3 hr of incubation. Growth of S. Typhi and E. coli O157:H7 was also completely inhibited after 6 hr of incubation. The antibacterial compounds from B. polyfermenticus CJ6 were purified by solid phase extraction (C18 Sep-pak cartridge), recycling preparative HPLC, and analytical HPLC. Ultra-high performance liquid chromatography and electrospray ionization tandem mass spectrometry analysis were used to identify the purified antibacterial compounds, which were confirmed to be five peptides (757.4153 Da, 750.3444 Da, 1024.5282 Da, 1123.6083 Da, and 1617.8170 Da).

• Journal of the Korean earth science society
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• v.28 no.7
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• pp.936-946
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• 2007

Analytical geopotential field in balance with the sectoral mode (the first symmetric mode with respect to the equator) of the Rossby-Haurwitz wave on the inclined rotation axis was derived in presence of superrotation background flow. The balanced field was obtained by inverting the divergence equation with the time derivative being zero. The inversion consists of two steps, i.e., the evaluation of nonlinear forcing terms and the finding of analytical solutions based on the Poisson's equation. In the second step, the forcing terms in the from of Legendre function were readily inverted due to the fact that Legendre function is the eigenfunction of the spherical Laplacian operator, while other terms were solved either by introducing a trial function or by integrating the Legendre equation. The balanced field was found to be expressed with six zonal wavenumber components, and shown to be of asymmetric structure about the equator. In association with asymmetricity, the advantageous point of the balanced field as a validation method for the numerical model was addressed. In special cases where the strength of the background flow is a half of or exactly the same as the rotation rate of the Earth it was revealed that one of the zonal wavenumber components vanishes. The analytical balanced field was compared with the geopotential field which was obtained using a spherical harmonics spectral model. It was found that the normalized difference lied in the order of machine rounding, indicating the reliability of the analytical results. The stability of the sectoral mode of Rossby-Haurwitz wave and the associated balanced field was discussed, comparing with the flrst antisymmetric mode.