• Journal of the Korean Magnetics Society
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• v.18 no.2
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• pp.54-57
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• 2008

Magnetic torquer, which uses torque between magnetic dipole moment and earth magnetic field, has been used to control attitude of satellites. In this work, we developed a magnetic torquer for small scientific satellite and test under environmental conditions of the satellite launching and orbital motion have been carried out. The developed magnetic torquer shows saturation magnetic dipole moment of $15Am^2$, linearity of 0.3 % in the range of ${\pm}12Am^2$, mass of 0.46 kg, and power consumption of 1 Watt at magnetic dipole moment of $10Am^2$.

• Korean Journal of Organic Agriculture
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• v.26 no.3
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• pp.515-532
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• 2018

Light is an essential and powerful element to animals. A light-emitting diode (LED) is most efficient in terms of economic benefits. The aim of the present study was to evaluate the effects of LED lighting time on milk production, milk composition, and the immune response of Holstein cows. Forty lactating cows were assigned to four experimental groups: control; natural daylight, treatment; am3-6, pm6-12 and pm6-am6. We found that there was no significant effect on the decrease ratio in milk production among the groups. Milk urea nitrogen (MUN) was significantly decreased in pm6-am6 and pm6-12 than the control. With regard to the hemolytic biochemical analysis, GLU was significantly increased and CRE, T-BIL were significantly decreased in the pm6-12 than the control. IGF-1 levels were significantly increased in pm6-12 compared to other groups. Besides, cortisol was significantly lowered in the pm6-12 than the control, while prolactin, IgA and IgG were not significant among the groups. In addition, catalase and glutathione peroxidase were also significantly increased in pm6-12 than the control. However, antioxidant enzyme activity and superoxide dismutase were not significant among the experimental groups. Therefore, it was concluded that LED lighting time had some impact on blood parameters and immune responses in dairy cows without any changes in milk production.

• Journal of Environmental Science International
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• v.14 no.5
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• pp.463-471
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• 2005

This study is designed to investigate the characteristics of $PM_{10}$ concentration and the chemical composition of heavy metallic components in the $PM_{10}$ sampled in western Busan from March to May, 2003. $PM_{10}$measurement was done during springtime of 2003, totaling 29 days: 9 days in March, 10 days in April and 10 days in May. With a sampling time of 24 hours, it started 9:00 AM on that day and ended 9:00 AM the next day. The mean contribution ratio of soil during springtime was $10.3\%$. Al had a significant correlation with Ca, Fe, Mg and Si and little correlation with Na, Ni and Zn.

• Journal of Powder Materials
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• v.24 no.6
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• pp.494-507
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• 2017

A three-dimensional physical part can be fabricated from a three-dimensional digital model in a layer-wise manner via additive manufacturing (AM) technology, which is different from the conventional subtractive manufacturing technology. Numerous studies have been conducted to take advantage of the AM opportunities to penetrate bespoke custom product markets, functional engineering part markets, volatile low-volume markets, and spare part markets. Nevertheless, materials issues, machines issues, product issues, and qualification/certification issues still prevent the AM technology from being extensively adopted in industries. The present study briefly reviews the standard classification, technological structures, industrial applications, technological advances, and qualification/certification activities of the AM technology. The economics, productivity, quality, and reliability of the AM technology should be further improved to pass through the technology adoption lifecycle of innovation technology. The AM technology is continuously evolving through the introduction of PM materials, hybridization of AM and conventional manufacturing technologies, adoption of process diagnostics and control systems, and enhanced standardization of the whole lifecycle qualification and certification methodology.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.17 no.1
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• pp.13-20
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• 2007

This study was performed to investigate the concentrations of PM($PM_{10}$, $PM_{2.5}$, $PM_{1}$) and it's affecting factors in the subway from line 1 to line 8 in Seoul metropolitan area, from Sep. 1 to 30, 2005. PM concentrations were measured at the entrances and centers in subway passenger cabins by a light scattering equipment. And the affecting factors to PM were estimated based on the number of passenger, door open and close and running area etc. The geometric means of $PM_{10}$, $PM_{2.5}$ and $PM_{1}$ concentration in Seoul subway passenger cabins were $214{\mu}g/m^3$, $86.6{\mu}g/m^3$ and $27.0{\mu}g/m^3$, respectively. These mean concentrations in subway carriage were higher when it ran on an underground track than on a ground track. And running time(7AM-9AM, 11AM-13PM, 6PM-8PM) significantly influenced to the concentrations of $PM_{10}$, $PM_{2.5}$ and $PM_{1}$. Daily profile of $PM_{10}$ and $PM_{2.5}$, $PM_{1}$ expressed as an 10 minutes average, showed similar variation pattern over day period. In correlation analysis, significant relations among $PM_{10}$, $PM_{2.5}$ and $PM_{1}$ were detected(p〈0.01). In particular, correlation coefficient between $PM_{10}$and $PM_{1}$ was highly significant(r=0.94). Further study is needed to identity the sources of PM in subway cabins and to compare pollutants concentration among subway lines.

• Journal of Environmental Science International
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• v.23 no.12
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• pp.2029-2034
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• 2014

To improve air quality around a broad way, Daegu Metropolitan city employed the clean-road system at a part of the broad way of Dalgubul (Daigubul-daero) in 2011. The clean-road system in general is operated two times (4 am, 2 pm) during summertime. In case of scorching alert, the system is operated 3 times a day (4 am, 2 pm and 4 pm). To evaluate the effect of air quality improvement due to the system, we analyzed the time variation of monthly mean particulate matter (PM10) concentration in recent 3 years (2011-2013). The improvement of air quality was estimated at about 5~15 % under the system.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.10
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• pp.1096-1103
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• 2008

This paper proposes an individual order predistortion linearizer using intermodulation distortion(IMD) generator for cancellation the third and the fifth IMD of power amplifier. The IMD generator for controlling the third and the fifth IMD consist of common Emitter amplifier and Schottky diode. These signals are generated by series feedback of Schottky diode to obtain the inverse AM/AM and AM/PM characteristics of power amplifier. The individual order predistorters are consisted of individual IMD generator, power splitter and combiner. The test results show that the third and the fifth IMD can be improved by a maximum 13.5 dB and 0.9 dB in case of CW 2-tone signals. Also, the Adjacent Channel Leakage Ratio(ACLR) can be improved 2.3 dB, 2.5 dB at ${\pm}0.885$ MHz, ${\pm}1.23$ MHz offset frequency for CD-MA IS-95 2FA signals.

• Korean Journal of Food Science and Technology
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• v.26 no.5
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• pp.520-525
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• 1994

This study was carried on the garlic-seasoning oil production by autoclaving method and evaporating method in order to research a developed method. The raw, flake, extract states of garlic was added 40%(w/w) of total amounts to corn salad oil. All samples treated with various conditions analyzed the volatile flavor components(VFC) during incubating ($40{\pm}2^{\circ}C$) and heating ($185{\pm}2^{\circ}C$). In the garlicseasoning oils, the contents of propane, pentane, methyl allyl trisulfide and diallyl trisulfide as the major VFC were decreased while the contents of propenal and hexanal increased according to the storage and heat treatment. The order of flavor contents among garlic states were raw>extract>flake, but flavor stability were raw>flake>extract states during storage, while flake>raw>extract states in heat treatment. VFC in garlic-seasoning oil made by evaporating method were about 66.1% level of those made by autoclaving method, but the changing tendency of their content during storage and heat treatment were shown to be similar. According to those results, autoclaving method and evaporating method were thought to the rational method in preparation of garlic-seasoning oil.

• Journal of Korean Society for Atmospheric Environment
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• v.11 no.3
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• pp.279-290
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• 1995

Recently in Korea, due to the significant drop of lead and bromine levels as a marker of autoemission source in the urban areas, the conventional application of receptor methods has many difficulties to properly apportion mass contribution of some sources. It is then needed to urgently develop alternative source profiles and identify new emission markers. Thus, the study has extensively examined the results obtained from using PAHs and elemental data for receptor modeling and has provided an opportunity to identify alternative source compositions and to determine a proper number of the ambient emission sources in Seoul area. The purpose of the study is to identify the sources of PM-10 and to estimate their mass contributions in Seoul area. Thus, a receptor model, target transformation factor analysis(TTFA) has been massively applied. The TTFA offers the possibility of determining the number of sources and their mass contributions. The input data used in this study are composed of two separate sets: fine (d$_{p}$ < 2.5.mu.m) and coarse (2.5.mu.m < d$_{p}$ < 10.mu.m) mode aerosol samples. Each sample was simultaneously collected by a PM-10 dichotomous sampler during the daytime(8 AM to 8 PM) and the nighttime(8 PM to 8 AM) from February to October 1993 on the Sungdong-Gu, Seoul. All the samples were analyzed to determine the levels of 10 inorganic elements by an XRF system as well as 14 PAHs by a HPLC. However, only 8 inorganic elements and 7 PAHs were used for the various statistical analysis.sis.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.10a
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• pp.131-136
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• 1999

This paper proposes the robot inverse calibration method using a neural networks. A highorder networks called Pi-Sigma networks has been used. The Pi-Sigma networks uses linear summing units in the hidden layer and product unit in output layer. The inverse calibration model which compensates the difference of joint variables only between measuring value and analytic value about the desired pose(position, orientation) of a robot is proposed. The compensated values are determined by using the weights obtained from the learning process of the neural networks previously. To prove the reasonableness, the SCARA type direct drive robot(4-DOF) and anthropomorphic robot(6-DOF) are simulated. It shows that the proposed calibration method can reduce the errors of the joint variables from $\pm$2$^{\circ}$to $\pm$ 0.1$^{\circ}$.