• ETRI Journal
• /
• v.31 no.6
• /
• pp.695-702
• /
• 2009

We propose a lens-drive unit composed of an ionic polymer-metal composite (IPMC) for an auto-focus compact camera module in cellular phones to solve the power consumption problem of voice coil motors which are widely used in commercial products. In this research, an IPMC incorporated into a lens-drive unit is designed to implement a large displacement in low-power consumption by using an anisotropic plasma treatment. Experimental results show that a camera module containing IPMCs can control and maintain the position of the lens by using proportional integral derivative control with a photo-reflective position sensor despite the non-linear actuation behavior of IPMCs. We demonstrate that the fabrication and commercialization of a lens actuator that has a large displacement and low power consumption using IPMCs is possible in the near future.

• Journal of the Korean Ceramic Society
• /
• v.42 no.4
• /
• pp.232-236
• /
• 2005

The etching characteristics of a $LiNbO_{3}$ optical waveguide structure have been investigated using neutral loop discharge plasma with the mixture of $C_{3}F_{8}$ and Ar and the bias power parameters. The etching rate and profile angle of optical waveguide with etching parameters were evaluated by scanning electron microscopy. Also, the etching RMS roughness was evaluated by atomic force microscopy. From the results of optimum etching conditions are the $C_{3}F_{8}$ gas flow ratio of 0.2 and the bias power of 300 W.

• Korean Journal of Materials Research
• /
• v.31 no.7
• /
• pp.392-396
• /
• 2021

Expensive PCBN or ceramic cutting tools are used for processing of difficult-to-cut materials such as Ti and Ni alloy materials. These tools have the problem of breaking easily due to their high hardness but low fracture toughness. To solve these problems, cutting tools that form various coating layers are used in low-cost WC-Co hard material tools, and research on various tool materials is being conducted. In this study, binderless-WC, WC-6 wt%Co, WC-6 wt%Co-1 wt% Mo₂C, and WC-6 wt%Co-2.5 wt% Mo₂C hard materials are densified using horizontal ball milled WC-Co, WC-Co-Mo₂C powders, and spark plasma sintering process (SPS process). Each SPSed Binderless-WC, WC-6 wt%Co-1 wt% Mo₂C, and WC-6 wt%Co-2.5 wt% Mo₂C hard materials are almost completely dense, with relative density of up to 99.5 % after the simultaneous application of pressure of 60 MPa and almost no significant change in grain size. The average grain sizes of WC for Binderless-WC, WC-6 wt%Co-1 wt% Mo₂C, and WC-6 wt%Co-2.5 wt% Mo₂C hard materials are about 0.37, 0.6, 0.54, and 0.43 ㎛, respectively. Mechanical properties, microstructure, and phase analysis of SPSed Binderless-WC, WC-6 wt%Co-1 wt% Mo₂C, and WC-6 wt%Co-2.5 wt% Mo₂C hard materials are investigated.

• Korean Journal of Materials Research
• /
• v.32 no.1
• /
• pp.44-50
• /
• 2022

Transition metal carbides (TMCs) are used to process difficult-to-cut materials due to the trend of requiring superior wear and corrosion properties compared to those of cemented carbides used in the cutting industry. In this study, TMC (TiC, TaC, Mo₂C, and NbC)-based cermets were consolidated by spark plasma sintering at 1,300 ℃ (60 ℃min) with a pressure of 60 MPa with Co addition. The sintering behavior of TMCs depended exponentially on the function of the sintering exponent. The Mo₂C-6Co cermet was fully densified, with a relative density of 100.0 %. The Co-binder penetrated the hard phase (carbides) by dissolving and re-precipitating, which completely densified the material. The mechanical properties of the TMCs were determined according to their grain size and elastic modulus: TiC-6Co showed the highest hardness of 1,872.9 MPa, while NbC-6Co showed the highest fracture toughness of 10.6 MPa^*m^1/2. The strengthened grain boundaries due to high interfacial energy could cause a high elastic modules; therefore, TiC-6Co showed a value of 452 ± 12 GPa.

• The Korean Journal of Food And Nutrition
• /
• v.23 no.4
• /
• pp.501-510
• /
• 2010

This study was conducted to assess blood components caused by metabolic syndrome increasing in postmenopausal elderly women. The blood samples of these subjects were analyzed to investigate the correlation of plasma taurine levels and plasma homocysteine levels, and serum lipid profiles. The subjects were 33 elderly women($72.8{\pm}4.4$ years). Their mean height, weight and BMI were $150.5{\pm}5.7\;cm$, $57.5{\pm}6.3\;kg$ and $25.4{\pm}2.5\;kg/m^2$. 16 women of this study subjects have been chronic diseases such as hypertension or diabetes. Their fasting blood glucose was $98.2{\pm}24.0\;mg/d{\ell}$, and their plasma total cholesterol (TC), HDL-C, LDL-C, triglyceride(TG) were $216.5{\pm}29.9$, $52.1{\pm}10.7$, $145.7{\pm}27.9$ and $141.2{\pm}59.6\;mg/d{\ell}$, respectively. Their blood lipid profiles were higher than the standard levels of metabolic syndrome, thus these levels of lipid profiles may play a role as risk factors on the elderly person. Plasma taurine level of the subjects was $278.5{\pm}48.1\;{\mu}mol/{\ell}$, and their plasma homocysteine level was $12.8{\pm}2.9\;{\mu}mol/{\ell}$. The concentration of plasma vitamin $B_{12}$ was significantly decreased by aging(p<0.05). The correlation of plasma homocysteine and plasma folate showed significantly negative(p<0.05). Thus, the decreased levels of plasma vitamin $B_{12}$ and folate by aging might affect on the plasma homocyteine concentration acting as a risk factor of cardiovascular diseases for elderly person. The correlation of plasma taurine and hemoglobin, and their platelet showed significantly positive(p<0.05). In conclusion, the diet on the elderly person is one of the important factors to prevent their health from chronic diseases. This study recommends that well balanced diets are needed for elderly person to keep their health and prevent from metabolic syndrome.

• Analytical Science and Technology
• /
• v.28 no.2
• /
• pp.125-131
• /
• 2015

A method was developed and fully validated for the determination of terbutaline, a β₂-receptor agonist, in human plasma. Plasma samples were prepared by solid-phase extraction with Sep-Pak silica, followed by high-performance liquid chromatography (HPLC). The terbutaline was pre-separated from the interfering components in plasma on a Luna C18 (2) column, and terbutaline and salbutamol as an internal standard were resolved and determined on a Luna Silica column. The two columns were connected by a switching valve equipped with silica pre-column. The pre-column was used to concentrate the terbutaline in the eluent from the C18 column before back-flushing onto the silica column with fluorescence detection at an excitation/emission wavelength of 276/306 nm. The method was shown to be specific by testing six different human plasma sources. Linearity was established for a concentration range of 0.4-20.0 ng/mL with a correlation coefficient of 0.9999. The lower limit of quantitation was 0.4 ng/mL with a precision of 10.1% as C.V.%.

• Journal of Nutrition and Health
• /
• v.17 no.4
• /
• pp.281-289
• /
• 1984

The present studies were designed to observe the effects of both dietary fat levels and P/S ratio on lipid components in plasma and tissues of young rats when cholesterol was supplemented at 1%(w/w) to four dietary groups providing total fat as 10%( LF ) or 45% ( HF ) of calories and P/S ratio as 0.2 or 4.0, Low Fat-0.2 : Low Fat-4.0 : High Fat-0.2 : High Fat-4.0. Plasma total cholesterol was increased almost to the same level in all dietary groups after the cholesterol supplement but the value of HF -0.2 was slightly higher than that of LF -0.2. Plasma TG was also increased in all dietary groups when cholesterol was supplemented but was more significantly increased in LF group than in HF group. HDL-cholesterol was slightly increased by cholesterol supplement but there was no effect by the total dietary fat level of previous diet. However, plasma HDL-cholesterol, total cholesterol and TG levels were slightly reduced in high fat diet of P/S 4.0. Total cholesterol per g -liver was higher in HF group than in LF group before and after cholesterol supplement even though it was increased more in LF group with cholesterol addition. Liver cholesterol was also higher in rats fed diets of P/S 4.0 at high fat level before and after cholesterol supplement. In contrast, total cholesterol per g-muscle was reduced by cholesterol supplement in all groups and it was significantly higher in LF than in HF. There was no significant effect in liver TG by total fat level and P/S ratio when cholesterol was supplemented. Muscle TG was lowered in all groups by cholesterol supplement but no effect by total fat level and P/S ratio.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.20 no.3
• /
• pp.135-140
• /
• 2020

Since the process gas that is essential in the semiconductor process is a harmful gas, it is an essential task to solve it in an environmentally friendly manner. Currently, the cleaning technology used in the semiconductor process is mostly a wet cleaning based on hydrogen peroxide developed in the 1970s, and the SC-1 cleaning liquid for removing particles on the surface uses a mixture of ammonia and hydrogen peroxide. Therefore, environmental problems are caused, and economic problems caused by excessive water use are also serious. For this reason, the products developed through this study are used to decompose the process harmful gas from the chamber outlet into a harmless gas before entering the vacuum pump, or by incineration and the gaseous components are deposited on the pump. I want to solve the problem. In this paper, CPS (Confined Plasma Source) is proposed to save environment and improve productivity by replacing harmful gases (N2, CF4, SF6⋯., Etc) which are indispensable in semi-contamination process with innocuous gases or incineration with plasma, to study.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2013.02a
• /
• pp.550-551
• /
• 2013

Large-area RF-driven ion source is being developed at Germany for the heating and current drive of ITER plasmas. Negative hydrogen (deuterium) ion sources are major components of neutral beam injection systems in future large-scale fusion experiments such as ITER and DEMO. RF ion sources for the production of positive hydrogen ions have been successfully developed at IPP (Max-Planck- Institute for Plasma Physics, Garching) for ASDEX-U and W7-AS neutral beam injection (NBI) systems. In recent, the first NBI system (NBI-1) has been developed successfully for the KSTAR. The first and second long-pulse ion sources (LPIS-1 and LPIS-2) of NBI-1 system consist of a magnetic bucket plasma generator with multi-pole cusp fields, filament heating structure, and a set of tetrode accelerators with circular apertures. There is a development plan of large-area RF ion source at KAERI to extract the positive ions, which can be used for the second NBI (NBI-2) system of KSTAR, and to extract the negative ions for future fusion devices such as ITER and K-DEMO. The large-area RF ion source consists of a driver region, including a helical antenna (6-turn copper tube with an outer diameter of 6 mm) and a discharge chamber (ceramic and/or quartz tubes with an inner diameter of 200 mm, a height of 150 mm, and a thickness of 8 mm), and an expansion region (magnetic bucket of prototype LPIS in the KAERI). RF power can be transferred up to 10 kW with a fixed frequency of 2 MHz through a matching circuit (auto- and manual-matching apparatus). Argon gas is commonly injected to the initial ignition of RF plasma discharge, and then hydrogen gas instead of argon gas is finally injected for the RF plasma sustainment. The uniformities of plasma density and electron temperature at the lowest area of expansion region (a distance of 300 mm from the driver region) are measured by using two electrostatic probes in the directions of short- and long-dimension of expansion region.

• Nuclear Engineering and Technology
• /
• v.54 no.10
• /
• pp.3717-3723
• /
• 2022

For the first time, two-dimensional temporal behavior of the edge localized mode (ELM) filament is measured in the edge tokamak plasma with a multi-channel electrical probe array (MCEP). MCEP, which has 16 floating probes (4 × 4), is mounted at the far scrape-off layer (SOL) region in the KSTAR. An electron temperature and an ion flux are measured by sideband method (SBM), which can achieve two-dimensional measurements with high time resolution. Furthermore, temporal evolutions of the electron temperature and the ion flux are obtained during the ELM occurrence. In the H-mode period, short spikes from ELM bursts are observed in measured plasma parameters, and the trend is similar to that of typical Hα signal. Interestingly, when blob-like ELM filaments crash the probe, the heat flux is significantly higher in a local region of the probe array. The results show that our probe array using the SBM can measure the ELM behavior and the plasma parameters without the effect of the stray current caused by the huge device. This study can provide valuable data needed to understand the interaction between the SOL plasma and the plasma facing components (PFCs).