• Journal of Biomedical Engineering Research
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• v.39 no.3
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• pp.140-145
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• 2018

Cancer is a major burden of human disease worldwide. Current chemotherapy has severe side effects because the drugs affect whole body nonspecifically. In addition, the drugs to reach cancer cells are very limited. Over the last two decades, Drug Delivery System (DDS) using nanoparticles has suggested promising results to improve current limitations. In this study, we prepared PLGA nanoparticles with different charge properties and observed their stability and internalization effect to cancer cells. Results using Dynamic Light Scattering (DLS) and Fourier Transform Infrared Spectroscopy (FTIR) confirmed the size and chemical composition of the nanoparticles. The stability of the nanoparticles in pH buffers were variable depending on charge properties. The nanoparticles showed different cytotoxicity and internalization effects to MCF-7 human breast cancer cells. In conclusion, we demonstrated the importance of delicately engineered nanoparticles for better DDS in cancer.

• Journal of the Korean Society of Clothing and Textiles
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• v.29 no.1 s.139
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• pp.1-12
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• 2005

This study was to suggest a feasible sizing system of infants and children's swim-suits. The basic body dimensions were selected after surveying the swimsuit manufacturers. The control dimensions and the secondary dimensions were taken from the 1997 National Anthropometric Survey data for the establishment of the sizing system. While in the current market swimsuit sizes were generally measured by the hip circumference for boys, and the bust and hip circumference for girls, the height was selected in this study as the control dimension because the height is well recognized by the customers and the KS standards specify the height to be the control dimension for infant's and children's wear. In the new sizing system of this study, the height was a control dimension, and hip was selected as a secondary dimension for boys. and bust and hip were selected as secondary dimensions for girls. Conclusively, in this study we suggest 12 sizes in case of 5cm height interval by the KS sizing system and 7 sizes in case of loom height interval by the current market sizing system, based on the height as a control dimension, for a standard swim-suit sizing system for infants and children.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.252-252
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• 2000

The Resistance Spot Welding (RSW) has been considered as an inherently safe and reliable method far joining metals, and has been widely employed, especially in automobile body assembly shops, as a manufacturing process. In recent years, the requirement for more sophisticated quality control procedures has considerably grown in the mass production industries. The object of the application of servo control to spot welding gun is the improvement of quality control in the spot welding, one of conventional industrial areas. The important factors affecting welding qualities (shear strength, nuggest size, indentation depth) are welding current, welding time, and gun press force. Welding current and welding time are controlled by welding timer. But, the conventional welding guns using compressed air are out of control in changing gun press forces in welding process. In this paper, a servo gun welding system having a AC servo motor and a PC control system is presented. The main object of this paper is to estimate the influence of gun press force changes in the welding process (press time -> welding time -> hold time) to welding qualities, and to evaluate welding qualities in real time, by recognizing the patterns of gun press forces changed in the welding process and comparing with the standard patterns.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.48 no.3
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• pp.185-191
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• 1999

The fuse used in the high voltage distribution line often fails due to the active ionization caused by the strong electric field at fuse terminal. To suppress the ionization at the high voltage and high capacity current limiting fuse, the particle size and compactness of silica sand, the design, length, notch number and material of element, the diameter and length of fuse body must be considered carefully. However, these are not many proper which is treated with the inherent interrupting characteristics from many parameters at present. Because of these reasons, time and effort are needed to develop the new type fuse by the fuse designers in relation with the inherent characteristics from each of parameters. In this paper we choose 7 parameters with weight value based on study and experimentation and analyzed the characteristics of arcing period. In addition, we proposed the experimental method to experimentation and analyzed the characteristics of arcing period. In addition, we proposed the experimental method to extract the optimal design parameters with minimal effort as related the mutual effect from each of the parameters.

• Journal of Ecology and Environment
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• v.32 no.3
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• pp.191-195
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• 2009

We monitored 38 hibernation sites of Myotis formosus in South Korea and recorded the number of bats occupying each site and assessed the micro-climate at the sites during four winters from 2005 to 2009 at. The mean rock temperature of the bat roosting sites was $13.2{\pm}1.4^{\circ}C$ and the mean body temperature of the hibernating bats was $13.3{\pm}1.3^{\circ}C$. The number of hibernating bats was negatively related to the size of the entrance and positively related to the minimum ambient temperature and humidity in the site interior. More bats hibernated in roosts with smaller entrances and higher minimum ambient temperatures, and more bats selected sites presenting a narrow temperature range. This study showed that the internal environments of hibernacula of M. formosus were highly stable despite dramatic variation in the external environment.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.11
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• pp.96-103
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• 2013

In this paper, resonant wireless power transfer systems are designed with double loop resonant coils for the resonant frequency of 150kHz. The transfer efficiency characteristics is analyzed according to the coil size, and the distance and misalignment between the coils. Then the change in efficiency is investigated when a human model is located between the resonant coils using the homogeneous human phantom of IEC-62311 standard. Also, in order to assess the safety of the wireless power transfer system, the induced current density inside the human model is calculated when it is exposed to the magnetic field of a plane wave and resonant coil. Then, the results are compared with the exposure limits in the EMF (electromagnetic field) safety guidelines.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.181.3-181
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• 2001

Recently, the study on development of electrical and electronic device is done to get miniature, high degrees of integration and efficiency by using inorganic materials. the study of Langmuir-Boldgett(LB) method that uses organic materials because of the limitation for the ultrasmall size. In this paper, to do research for medical artificial organs as well as principal parts living body thin film application, electrical properties of L-$\alpha$-DLPC Langmuir(L) films were investigated a displacement current measuring technique with pressure stimulation. We give pressure stimulation into organic thin films and then manufacture a device under the accumulation condition that the state surface pressure is 20[mN/m]. LB layers of L-$\alpha$-DLPC deposited by LB method ...

• ETRI Journal
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• v.24 no.5
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• pp.333-340
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• 2002

We propose a new process technique for fabricating very high-density trench MOSFETs using 3 mask layers with oxide spacers and a self-aligned technique. This technique reduces the device size in trench width, source, and p-body region with a resulting increase in cell density and current driving capability as well as cost-effective production capability. We were able to obtain a higher breakdown voltage with uniform oxide grown along the trench surface. The channel density of the trench DMOSFET with a cell pitch of 2.3-2.4 ${\mu}m$ was 100 Mcell/$in^2$ and a specific on-resistance of 0.41 $m{\Omega}{\cdot}cm^2$ was obtained under a blocking voltage of 43 V.

• Journal of the Korean institute of surface engineering
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• v.36 no.2
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• pp.176-184
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• 2003

New lubricant film of organic and inorganic composite resin was developed to improve the press formability of galvannealed steel sheets (GA) for automotive body panels. The frictional coefficient of lubricant GA steel sheets is about 20% superior to that of uncoated GA. The current range of spot welding of lubricant GA is similar to that of the uncoated GA, but the burning trace of spot welding is inferior to that of the uncoated GA in the oiling condition. The alkaline degreasability of lubricant GA shows 100% in alkaline degreasing condition of automotive company. The size and shape of the phosphated coating layer are similar to those of the uncoated GA sheet. The powdering property of the lubricant GA gives rise to 20∼50% improved property compared with the uncoated GA sheet.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.592-597
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• 2003

To solve a problem of micro drive due to small size and portability, it is necessary to understand and to investigate micro drive widely ,deeply. So, we performed modal analysis of suspension of micro drive, and load/unload experiment for Input current to VCM coil and disk speed. To determine the effect of ramp profile, curve fitting of lateral speed is performed with equation of speed. The results indicate that small load/unload speeds decrease the number of head/disk contacts, and during unloading process, low disk speed increase the number of head/disk contacts.