• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.8
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• pp.1802-1809
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• 2009

Abstract The typical distribution systems have the power flow from distribution substations (sources) to customers (load) only as one direction. However, in the case where distributed generations (DG) such as PV system and wind power systems are connected to distribution systems, the DG output variations to distribution systems, so called reverse power flow, may cause the bi-directional power flow. So, the reverse power flow has severe impacts on typical power system, for example power quality problems, protection coordination problems, and so on. Especially, protection devices (sectionalizer) in primary feeder of distribution system interconnected with distributed generations may cause problems of malfunction, and then many customers could have problems like an interruption. So, this paper presents the bi-directional operation algorithm of protection devices to overcome the problems like mal-function. And, also this paper shows the effectiveness of proposed method by using both PSCAD/EMTDC software and test facility of protection devices to simulate the field distribution systems.

• The KIPS Transactions:PartD
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• v.13D no.5 s.108
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• pp.641-650
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• 2006

XML has the characteristics of self-describing and uses DTD or XML schema in order to constraint its structure. Even though the XML schema is only at the stage of recommendation yet, it will be prevalently used because DTD is not itself XML and has the limitation on the expression power. The structure defined by the XML schema as well as the data of the XML documents can vary due to complex reasons. Those reasons are errors in the XML schema design, new requirements due to new applications, etc. Thus, we propose XML schema evolution operators that are extracted from the analysis of the XML schema updates. These schema evolution operators enable the XML schema updates that would have been impossible without supporting tools if there are a large number of XML documents complying the U schema. In addition, these operators includes the function of automatically finding the update place in the XML documents which are registered to the XSE system, and maintaining the XML documents valid to the XML schema rather than merely well-formed. This paper is the first attempt to update XML schemas of the XML documents and provides the comprehensive set of schema updating operations. Our work is necessary for the XML application development and maintenance in that it helps to update the structure of the XML documents as well as the data in the easy and precise manner.

• Journal of Preventive Medicine and Public Health
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• v.29 no.4 s.55
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• pp.853-861
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• 1996

Pneumoconiosis is one of the major problem in the field of occupational health at Korea. Therefore, the efficient diagnosis of pneumoconiosis is a hot issue on the occupational health program. The author executed this study to estimate the diagnostic value of high resolution computed tomography(HRCT) compared with chest radiography for screening of welder's lung. HRCT was introduced very recently for the diagnosis of pneumoconiosis, however, the diagnostic value for screening of welder's lung - principally nonfibrogenic and reversible - has not been evaluated. The subjects were fifty cases of welder's lung or suspected cases who had been collected between 1989 and 1994 from one shipyard and continuously followed-up on the basis of in-plant periodic health check program. We applied both chest radiography and HRCT on the same subjects from May 1 to 30, 1996. The images were evaluated by two careered radiologists independently. The findings of chest radiography were classified into four category by ILO classification, and the findings of HRCT according to the criteria of Bergin et al. The concordance between two radiologists expressed with Kendall's tau-b was 0.72 by chest radiography and 0.44 by HRCT- that is, interobserver variation of HRCT was bigger than that of chest radiography. The concordance between the two different methods was highly variable as 0.44 by radiologist A and 0.06 by radiologist B - that is, interobserver variation was very big. However, HRCT looked more detectable for the minor parenchymal change. These findings suggested that it is not appropriate to use HRCT routinely for screening of welder's lung due to lack of diagnostic criteria, and feasibility, acceptability and economic aspects. Nevertheless, HRCT might be recommendable in the case of equivocal parenchymal features on the chest radiography, unexplained respiratory symptoms, and/or lung function abnormalities suggestive of interstitial fibrosis.

• Journal of the Korean Society for Nondestructive Testing
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• v.24 no.4
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• pp.354-361
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• 2004

This Paper describes a crack scattering model for SH wave based on the boundary integral equation(BIE) method, where the fundamental unknown is crack opening displacement(COD). When a time harmonic plane wave was incident on a 2-D isolated crack (slit) of width 2a, the COD distributions were numerically calculated as a function of ka. The calculated COD agreed well with results obtained with other methods. The far-field scattering amplitude, which completely characterizes the flaw response, was calculated in two ways. The Kirchhoff approximation and the BIE-COD exact formulation were compared in terms of incidence angle and frequency ka in a pulse-echo mode. Maximum response was obtained for both methods at the specular reflection direction. Away from the specular direction, the Kirchhoff approximation becomes less accurate. The time domain crack response was also calculated using a band-limited spectrum of center frequency 10 MHz. At oblique incidence to the crack both methods show the existence of an antisymmetric flash points occurring from the crack edge. The Kirchhoff approximation provides an exact time interval between flash points, although it unrealistically gives the same amplitude.

• Korean Journal of Food Science and Technology
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• v.33 no.5
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• pp.551-559
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• 2001

Sodium nitrite which is added in processing of meat process product to develope color and to keep bacteria from growing, produces toxic substance after reacting, bring about deterioration by oxidation and toxic substance. So natural material is needed to substitute this sodium nitrite for. Chitosan which is made of chitin by processing of deacetylase, has various function of antibiosis and antimutation. We studied about the substitution effect of chitosan against sodium nitrite in pork sausage. As a result, of storing the sausage, antimicrobial effect of sodium nitrite was detected by 0.35% of chitosan(M.W. 30 kDa). This chitosan had same color developing effect even though addition content of sodium nitrite reduced until 15 ppm which is less than 1/10 of standard level. And chitosan decreased fast a residual nitrite. This result shows that chitosan inhibited a formation of nitrosamine.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.4
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• pp.201-208
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• 2017

Recently, the installation of photovoltaic(PV) systems has been increasing due to the worldwide interest in eco-friendly and abundant solar energy. On the other hand, a PV system has approximately 25% power loss while the energy generated from solar cells is transformed to the power coupling point through a power conversion system (DC/AC). If the output voltage of a string in the PV system is lower than the operating range of the inverter when a part of module in the string has a shadow due to weather conditions, the string is not synchronized and the whole efficiency of output power in a PV system may be reduced significantly. Therefore, to overcome this problem, this paper proposes a novel control method to compensate for the lower voltage by introducing a DC/DC voltage regulator for each string in a PV system, which adopts a concept for MPPT (Maximum Power Point Tracking) control function using the P&O algorithm and adopts constant voltage control method used in an existing inverter. This paper also implements a 2kW DC/DC voltage regulator based on the proposed algorithm and performs a variety of scenario-based experiments. From the simulation result, it was confirmed that the operation efficiency in the proposed method is improved compared to the existing method.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.31 no.1 s.49
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• pp.35-41
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• 2005

We investigated the effects of skin hydration and anti-irritation of exopolysaceharide (GF-glucan) produced from submerged culture of Grifola frondosa. The moisturizing effects and trans-epidermal water loss (TEWL) of GF-glucan in cosmetic products (O/W emulsion) were clinically studied. GF-glucan showed good skin hydration effects when compared with sodium hyaluronate which is a commonly using moisturizer. The skin protective effects of GF-glucan against sodium lauryl sulfate (SLS) were also found. Twice a day application of the CF-glucan to skin reduced local inflammation remarkably. Irritant reactions were assessed by various aspects of skin function, erythema (skin color reflectance), hydration (electrical capacitance) and TEWL. In the human skin test, 5-day treatment of the GF-glucan was found to reduce SLS-induced skin erythema and Improve bier regeneration. Taken all together, GF-glucan should be a very useful cosmetic ingredient, as a moisturizer, and a protecting agent for various skin irritations.

• Journal of the Korean Magnetics Society
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• v.18 no.4
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• pp.147-153
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• 2008

It has been well-known that the Fe/GaAs heterostructure has a small lattice mismatch of 1.4% between Fe and GaAs, and the Fe layer is grown epitaxially on the the GaAs substrate. There are rich physics are observed in the GaAs/Fe interface, and the spininjection is actively studied due to its potential applications for spintronics devices. We fabricated Fe wedge layer in the thickness range $0{\sim}3.4$ nm on the GaAs(100) surface with 5-nm thick Au capping layer. The magnetic anisotropy of the Fe/GaAs system was investigated by employing Brillouin light scattering(BLS) measurements in this study. The spin wave excitation of Fe layer was studied as the function of intensity and the in-plane angle of external magnetic field, and thickness of Fe layer. Also these various dependences were analyzed with analytic expression of spin wave surface mode in order to determine the magnetic anisotropies. It has been found that the GaAs/Fe/Au system has additional uniaxial magnetic anisotropy, while the bulk Fe has biaxial anisotropy. The uniaxial anisotropy shows increasing dependency respected to decreasing thickness of Fe layer while biaxial anisotropy is reduced with Fe film thickness. This result allows the analysis that the uniaxial anisotropy is originated from interface between GaAs surface and Fe layer.

• Journal of Food Hygiene and Safety
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• v.34 no.4
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• pp.374-379
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• 2019

This study developed predictive growth models of Salmonella enterica Serovar Typhimurium on lettuce washed with chlorine (100~300 ppm) and ultrasound (US, 37 kHz, 380 W) treatment and stored at different temperatures ($10{\sim}25^{\circ}C$) using a polynomial equation. The primary model of specific growth rate (SGR) and lag time (LT) showed a good fit ($R^2{\geq}0.92$) with a Gompertz equation. A secondary model was obtained using a quadratic polynomial equation. The appropriateness of the secondary SGR and LT model was verified by coefficient of determination ($R^2=0.98{\sim}0.99$ for internal validation, 0.97~0.98 for external validation), mean square error (MSE=-0.0071~0.0057 for internal validation, -0.0118~0.0176 for external validation), bias factor ($B_f=0.9918{\sim}1.0066$ for internal validation, 0.9865~1.0205 for external validation), and accuracy factor ($A_f=0.9935{\sim}1.0082$ for internal validation, 0.9799~1.0137 for external validation). The newly developed models for S. Typhimurium could be incorporated into a tertiary modeling program to predict the growth of S. Typhimurium as a function of combined chlorine and US during the storage. These new models may also be useful to predict potential S. Typhimurium growth on lettuce, which is important for food safety purposes during the overall supply chain of lettuce from farm to table. Finally, the models may offer reliable and useful information of growth kinetics for the quantification microbial risk assessment of S. Typhimurium on washed lettuce.

• Journal of Animal Science and Technology
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• v.61 no.5
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• pp.260-271
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• 2019

The objective of this study was to determine the effect of different stocker management programs on skeletal muscle development and growth characteristics, satellite cell (SC) activity in growing-finishing beef cattle as well as the effects of SC-conditioned media on preadipocyte gene expression and differentiation. Fall-weaned Angus steers (n = 76; $258{\pm}28kg$) were randomly assigned to 1 of 4 stocker production systems: 1) grazing dormant native range (NR) supplemented with a 40% CP cottonseed meal-based supplement ($1.02kg{\cdot}steer^{-1}{\cdot}d^{-1}$) followed by long-season summer grazing (CON, 0.46 kg/d); 2) grazing dormant NR supplemented with a ground corn and soybean meal-based supplement fed at 1% of BW followed by short-season summer grazing (CORN, 0.61 kg/d); 3) grazing winter wheat pasture (WP) at high stocking density (3.21 steers/ha) to achieve a moderate rate of gain (LGWP, 0.83 kg/d); and 4) grazing winter WP at low stocking density (0.99 steers/ha) to achieve a high rate of gain (HGWP, 1.29 kg/d). At the end of the stocker (intermediate harvest, IH) and finishing (final harvest, FH) phases, 4 steers / treatment were harvested and longissimus muscles (LM) sampled for cryohistological immunofluorescence analysis and SC culture assays. At IH, WP steers had greater LM fiber cross-sectional area than NR steers; however, at FH, the opposite was observed (p < 0.0001). At IH, CORN steers had the lowest Myf-5+:Pax7+ SC density (p = 0.020), while LGWP steers had the most Pax7+ SC (p = 0.043). At FH, CON steers had the highest LM capillary density (p = 0.003) and their cultured SC differentiated more readily than all other treatments (p = 0.017). At FH, Pax7 mRNA was more abundant in 14 d-old SC cultures from HGWP cattle (p = 0.03). Preadipocytes exposed to culture media from proliferating SC cultures from WP cattle isolated at FH had more $PPAR{\gamma}$ (p = 0.037) and less FABP4 (p = 0.030) mRNA expression compared with NR cattle. These data suggest that different stocker management strategies can impact skeletal muscle growth, SC function, and potentially impact marbling development in growing-finishing beef cattle.