• Journal of Biomedical Engineering Research
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• v.28 no.6
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• pp.832-839
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• 2007

In this study, a new bicycle system was developed to improve muscular strength using the Magneto-Rheological(MR) rotary brake. The friction load of the MR rotary brake is adjusted according to muscle strength of the subjects. The characteristic of muscular strength was studied with various friction loads of MR rotary brake. The friction load was occurred with the current, applied to the MR. rotary brake. Experiments was composed of several cycling trials for various friction loads. In training programs involving muscle improvement, it is necessary to confirm muscle activity and fatigue. To measure the muscle activity and fatigue, EMG signals of rectus femoris (RF), biceps femoris (BF), tensor fasciae latae (TFL), vastus lateralis (VL), vastus medialis (VAS), gastrocnemius (GAS), tibialis anterior (TA) and soleus (SOL) muscles were collected with surface electromyography and analyzed into time and frequency domain. The experimental results showed that the muscle activity according to the applied current to the MR rotary brake was significantly different. The more the current was applied, the higher value of the integrated EMG (IEMG) was obtained. Especially, the magnitude of IEMG of the RF, BF, TFL and VL varied in direct proportion to the current. However, there was not significant in the median frequency as the cycling time continue.

• Economic and Environmental Geology
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• v.19 no.2
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• pp.153-163
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• 1986

Paleomagnetic and geological studies of volcanic and sedimentary rocks of Jeju Island have been carried out to determine the position of virtual geomagnetic pole(VGP), and to estimate the geological sequence and their age. As a result of paleomagnetic studies, the reversal polarities are measured in the Sanbangsan trachyte and Hwasun formation, and the normal are the rest. In case of normal polarity, the mean values of declination and inclination are $2.3^{\circ}$ and $48.4^{\circ}$, respectively, and the average value of VGP is $85.4^{\circ}N$ and $79.9^{\circ}W$. The locations of VGP's are coincident with those obtained from world-wide Plio-Pleistocene rocks. The Hwasun formation and Seongsan formation which have been known to be sedimented in the similar time in the 2nd-stage of volcanic eruption, possess reversal and normal polarities, respectively. This fact brings about the result that two formations should be separated in a sense of geological sequence. Consequently, the geological sequence of the 2nd-stage of volcanic eruption is Pyoseonri basalt-Seoguipo hawaiite-Hwasun formation-Seongsan formation-Jungmun hawaiite-Sanbangsan trachyte. Referring to the paleomagnetic studies and the previous and present geological studies, Seoguipo formation corresponds to the Gauss normal epoch, the 2nd-stage of volcanic eruption to Matuyama reversed epoch, and the 3rd-, 4th-, and 5th-stages to Brunhes normal epoch. Therefore, the Seoguipo formation is mostly sedimented during late Pliocene and/or presumably extended to the early Pleistocene. The rocks of the 2nd- to 5th-stage are formed later than this.

• Journal of the Korean Society for Heat Treatment
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• v.22 no.5
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• pp.290-297
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• 2009

In case of using Asymmetric Bipolar Pulsed DC (ABPD) power generator, thin film is efficiently deposited as ions are getting higher energy by suppressing target poisoning and electric arc. In this article, the mechanical properties of CNx thin films deposited on the STS 316L were compared with DC and ABPD power generators. The CNx thin films deposited with ABPD clearly improved wear resistance by higher ratio of sp3CN as compared with DC. Nb interlayer affected to increase the value of 10N of adhesion between CNx thin films and substrate. But, CNx thin films deposited with ABPD couldn't endure to wear load and decreased wear resistance as the films were too thinner than substrate. Nevertheless the higher substrate bias energy applied to perform the dense films, it wasn't shown benefits about the wear properties from DC sputtering. But, in case of using ABPD sputtering, the wear resistance was largely improved without changing morphology despite of thin films.

• Journal of The Korean Society of Grassland and Forage Science
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• v.18 no.3
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• pp.217-222
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• 1998

This experiment was carried out to investigate effects of herbicide application method on Calysteria jcqoonica control and corn yield at the forage experimental field, grassland and forage crops division, National Livestock Research Institute, RDA, Suwon from 1996 to 1997. The experiment was arranged in a randomized block design with three replication. The herbicide application consisted of control, 2~3 leaf stage(Dicamba), 5~6 leaf stage(Dicamba) and soil treatment (Pendimethalin). The hybrid of corn used in this experiment was P 3352. The results obtained are summarized as follow; 1. The plant height was the lowest at control and the highest at Dicamba treatment in 5~6 leaf stage, but no significant difference was found among herbicide application method at ear height. Tasseling and silking date were delayed 2~3 day at control. The length and weight of ear were highest at Dicamba treatment in 2~3 leaf stage. 2. The herbicide injury of corn was very slightly after 10-20 day, but corn was recovered soon. The weed control value was 94.2~67.5% at herbicide application plot. 3. The fresh and dry matter yield of Dicamba treatment in 2-3 leaf stage was highest as 42,878 and 16,033kg/ha, respectively. The application of Dicamba increased the DM yield of corn by 13~30%. 4. Herbicide application time had little effect on the ADF, NDF and CP contents, but the forage quality of ear was higher than that of stover. The result of this experiment indicate that the application of Dicamba in 2~6 leaf stage of corn will remove almost all of Calysreria jqonica and increase DM yield of com.

• Tribology and Lubricants
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• v.36 no.3
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• pp.139-146
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• 2020

Global warming has led to an increase in demand of eco-friendly vehicles, such as electric cars, for reducing greenhouse gas emissions, and especially, regulating carbon dioxide generation. In addition, electric vehicles are equipped with an electric drive-type hermetic scroll compressor and a refrigerant, which exhibit current and future trends of using environmentally friendly refrigerants, including R-1234yf. In this study, polyol ester-based refrigeration oils are prepared via condensation esterification of polyol and fatty acids. The oils can be combined with R-1234yf refrigerant for applications in air conditioning and cooling systems of electric vehicles. The structure of synthetic polyol esters is confirmed via ¹H-NMR and FT-IR spectrum analysis, and the composition of the polyol ester is analyzed via gas chromatogram analysis. Furthermore, kinematic viscosity, viscosity index, total acid value, pour point, and color are analyzed as fundamental physical properties of the synthetic polyol esters. The compatibility and chemical stability of the synthetic polyol ester combined with the R-1234yf refrigerant are obtained via high temperature and high pressure oil-resistant refrigerant tests. The changes in the oil color and catalyst activity are observed before and after the experiment to determine whether it is suitable as a refrigerator oil.

• KIISE Transactions on Computing Practices
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• v.21 no.12
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• pp.786-791
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• 2015

The environment of Internet of Things (IoT) wherein various devices are connected through the Internet with value-added network functions, is currently a subject of active study. Accordingly, the existing computing environment based on desktop or mobile systems is being expanded into a computing environment of more diverse devices. Because the response of program launching is important in terms of User Experience (UX) in IoT environments, the technology for guaranteeing rapid response of program launching in IoT devices is getting the focus of much current research. In this paper we analyze the Zygote technique, which is being used for faster program execution in Android systems, and, based on our results, we propose an address space maintaining scheme for the rapid launching of programs for use in Linux-based systems. Our scheme utilizes the Copy on Write (CoW) technique in Linux systems as well as the Zygote technique of Android systems. In order to evaluate the proposed scheme, we implemented our scheme on Linux systems and performed several experiments. The experimental results show that the proposed scheme shortens the launching time up to 99%, compared to the existing technique.

• Journal of the Korean Magnetics Society
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• v.7 no.3
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• pp.146-151
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• 1997

Buffer (t $\AA$)/ CoFe(35$\AA$)/Cu (50$\AA$)/Co (35$\AA$) sandwiches prepared by dc magnetron sputtering on Corning glass substrates using the $Co_{90}Fe_{10}$ and Co layers with different coercivities. Dependence of magnetoresistance on the type and thickness of buffer layers, and on the thickness of Cu and the magnetic layers in buffer/ CoFe/Cu /Co sandwiches were investigated. Magnetoresistance ratio and saturation field $H_s$ increased as thickness of the buffer layer becomes thicker, then decreased smoothly after a maximum value. An improved filed sensitivity was realized with the $Ni_{81}Fe_{19}$ buffer layer.

• Korean Journal of Materials Research
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• v.13 no.5
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• pp.333-337
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• 2003

We report a new fabrication process for carbon nanotube field emitters with high performance. The key of the fabrication process is trim-and-leveling the carbon nanotubes grown in trench structures by employing a planarization process, which leads to a uniform distance from the carbon nanotube tip to the electrode. In order to enable this processing, spin-on-glass liquid is applied over the CNTs grown in trench to have them stubborn adhesion among themselves as well as to the substrate. Thus fabricated emitters reveal an extremely stable emission and aging characteristics with a large current density of 40 ㎃/$\textrm{cm}^2$ at 4.5 V/$\mu\textrm{m}$. The field enhancement factor calculated from the F-N plot is $1.83${\times}$10^{5}$ $cm^{－1}$ , which is a very high value and indicates a superior quality of the emitter originating from the nature of open-tip and high stability of the carbon nanotubes obtained new process.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.906-909
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• 2006

The secondary electron emission coefficient $({\gamma})$ of the cathode is an important factor for improving the discharge characteristics of AC-PDPs because of its close relationship to discharge voltage. In AC-PDPs, MgO is most widely used as a surface protective layer. In this experimental, we have investigated the electronic structure of the energy band structure of the MgO layer responsible for the high ${\gamma}$. The MgO layers have been deposited by electron beam evaporation method, where the $O_2$ partial pressures have been varied as 0, $5.2{\times}10^{-5}$ torr, $1.0{\times}10^{-4}$ torr, and $4.1{\times}10^{-4}$ torr, in this experiment. It is noted that work function that is energy gap between surface and first defect level of MgO layer has the lowest value for the highest O2 partial pressure of $4.1^{\ast}10^{-4}$ Torr.

• Progress in Superconductivity and Cryogenics
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• v.18 no.1
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• pp.41-45
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• 2016

The technology of supplying the electric power by wireless power transfer (WPT) is expected for the next generation power feeding system since it can supply the power to portable devices without any connectors through large air gap. As such a technology based on strongly coupled electromagnetic resonators is possible to deliver the large power and recharge them seamlessly; it has been considered as a noble option to wireless power charging system in the various power applications. Recently, various HTS wires have now been manufactured for demonstrations of transmission cables, motors, MAGLEV, and other electrical power components. However, since the HTS magnets have a lower index n value intrinsically, they are required to be charged from external power system through leads or internal power system. The portable area is limited as well as the cryogen system is bulkier. Thus, we proposed a novel design of wireless power charging system for superconducting HTS magnet (WPC4SM) based on resonance coupling method. As the novel system makes possible a wireless power charging using copper resonance coupled coils, it enables to portable charging conveniently in the superconducting applications. This paper presented the conceptual design and operating characteristics of WPC4SM using different shapes' copper resonance coil. The proposed system consists of four components; RF generator of 370 kHz, copper resonance coupling coils, impedance matching (IM) subsystem and HTS magnet including rectifier system.