• Journal of Environmental Science International
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• v.16 no.11
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• pp.1279-1285
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• 2007

The activated carbon was prepared from waste citrus peels using NaOH. With the increase of NaOH ratio, iodine adsorptivity and specific surface area of the activated carbon prepared were increased, but activation yield was decreased. The optimal condition of activation was at 300% NaOH and $700^{\circ}C$ for 1.5 hr. For the activated carbon produced under optimal condition, iodine adsorptivity was 1,006 mg/g, specific surface area was $1,356 m^2/g$, and average pore diameter was $20{\sim}25{\AA}$. From the adsorption experiment for benzene vapor in fixed bed reactor, it was found that the adsorption capacity of activated carbon prepared from waste citrus peel was higher than that of activated carbon purchased from Calgon company. This result implied that the activated carbon prepared from waste citrus peel could be used for gas phase adsorption.

• Carbon letters
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• v.14 no.3
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• pp.180-185
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• 2013

In this study, activated carbons nanofibers (ACNFs) were prepared from polyacrylonitrile-based nanofibers by physical ($H_2O$ and $CO_2$) and chemical (KOH) activation. The surface and structural characteristics of the porous carbon were observed by scanning electron microscopy and X-ray diffraction, respectively. Pore characteristics were investigated by $N_2$/77K adsorption isotherms. The specific surface area of the physically ACNFs was increased up to $2400m^2/g$ and the ACNFs were found to be mainly composed of micropore structures. Chemical activation using KOH produced ACNFs with high specific surface area (up to $2500m^2/g$), and the micropores were mainly found in the ACNFs. The physically and chemically ACNFs showed both mainly type I from the International Union of Pure and Applied Chemistry classification.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.7 no.1
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• pp.174-184
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• 1997

Activated carbons were prepared from palm chars by steam activation. The effect of the activation temperature and time, steam concentration and flux on the n -butane adsorption properties were investigated on the basis of surface area, pore analysis and n-butane adsorption. The amount of n -butane adsorption increased with steam concentration and steam flux at higher activation temperature to the $900^{\circ}C$, however this tendancy on the activated carbons were not observed at the temperature above $900^{\circ}C$, It was shown that surface area was 978 $\textrm{m}^2$/g, average pore size was 9.3 $\AA$ and n-butane adsorption was 5.9 g /100ml in the activated carbons, prepared at $900^{\circ}C$, 185 minutes.

• Carbon letters
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• v.6 no.1
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• pp.1-5
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• 2005

Isotropic pitch based carbon fibers were exposed to isothermal oxidation in carbon dioxide gas to study the activation kinetics under the temperature of 800~$1100^{\circ}C$. The kinetic equation $f=1-{\exp}(-at^b)$ was introduced and the constant b was obtained in the range of 0.92~1.25. It was shown that the activated carbon fiber shows the highly specific surface area (SSA) when the constant b comes close to 1. The activation kinetics were evaluated by the reaction-controlling regime (RCR) according to changes of the apparent activation energy with changes of the conversion. It was observed that the activation energies increase from 47.6 to 51.2 kcal/mole with the conversion increasing from 0.2 to 0.8. It was found that the pores of the activated carbon fiber under the chemical reaction were developed well through the fiber.

• Applied Chemistry for Engineering
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• v.17 no.5
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• pp.532-538
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• 2006

The carbonization and activation conditions for the PAN-based ACF of various grade were investigated to obtain the optimun activation condition with high surface area. And the surface properties and the absorption performance of toxic gas for terror were examined toward the PAN-ACF with the highest surface area. In the test results the surface area increased with increase of the activation temperature, but decreased with increase of the carbonization temperature. After carbonization condition ($900^{\circ}C$-15min) and activation condition ($900^{\circ}C$-30 min), we got the ACF with the highest surface area of $1204m^2/g$. In the absorption test of iodine and toxic gas for terror, this ACF showed more excellent absorption performance than the existing carbon-based adsorbent. Also, in order to give the function characteristic for a selective absorption, the stable nanoparticles of the Ag, Pt, Cu, Pd were prepared and impregnated on the PAN-based ACF in replacement of the existing method supporting metal catalysis. And were analyzed the surface characteristics and the $SO_{2}$ adsorption characteristics. In the $SO_{2}$ absorption performance test of the PAN-ACF with the impregnated nanoparticles, it wasn't change breakthrough time of Ag, Pt, Cu nanoparticle supported the PAN-ACF comparing with breakthrough time (326 sec) of the non supported PAN-ACF but Pd nanoparticle supported the PAN-ACF achieved excellent $SO_{2}$ absorption performance which has break-through time 925 sec.

• Journal of the Korean Ceramic Society
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• v.38 no.10
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• pp.928-935
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• 2001

In this study, two kinds of activated carbon fibers were prepared from PAN-based stabilized fibers by physical activation with steam. The variations in specific surface area, amount of iodine adsorption and pore size distribution of the activated carbon fibers after the activation process were discussed. The activated carbon fibers were prepared by two different methods, namely a 1- and 2-step method. For the 2-step method, carbonization of fibers in $N_2$ atmosphere was carried out to make carbon fibers and then activated by steam. In normal two step steam activation, BET surface area of about $1019m^2/g$ was obtained in the study. In the 1-step steam activation process, the carbonization and activation were simultaneously carried out. In the one step steam activation, BET surface area of $1635m^2/g$ was obtained after heat-treatment at $990^{\circ}C$. However, nitrogen adsorption isotherms for oxidized PAN based activated carbon fibers that were prepared by both methods were type I in the Brunauer-Deming-Deming-Teller (BDDT) classification even though they have different BET surface areas, amounts of iodine adsorption and pore size distributions.

• Journal of Korean Society of Rural Planning
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• v.15 no.1
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• pp.89-99
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• 2009

I wish to establish Kwang-shi Han-woo agriculture theme park furtherance plan that take advantage of unique area resource of homebred cattle meat sale restaurant of the Chungchong-namdo Yesan County Kwang-Shi Ran-woo village. Improve regional income that develops Kwang-shi Ran-woo area that is made up a rest and experience space that escapes in sightseeing of Ran-woo meat putting first that is food, and contribute in economy activation by promotes City-Farm exchange, and is behind present, and is expected that contributes in farm village area activation that is stagnated Ran-woo specialization area of whole country scale. Kwang-shi Han-woo agriculture-farm village theme park plan is thought that active participation of thorough environmental protection and local resident is necessary condition as plan that take advantage of peculiar latency resource of area. In plan process, reflected various opinion of local resident representatives to space but there is a little insufficient page, and sees that also thorough environment analysis should be preceded. Hereafter, see that correction' repletion need a little through thorough grasping of latency resource that put together thorough natural environment investigation. in Yesan County with analysis at final design step. But, see that plan of theme park that take advantage of characteristic resource in farm village, especially situation of Ran-woo farmhouses that is suffering now difficulty as plan that do appropriateness of city in area activation and economical income guarantee side of farmhouse inhabitants.

• Carbon letters
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• v.13 no.4
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• pp.236-242
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• 2012

Poly(vinylidene chloride) (PVDC)-derived nanoporous carbons were prepared by various activation methods: heat-treatment under an inert atmosphere, steam activation, and potassium hydroxide (KOH) activation at 873, 1073, and 1273 K. The pore structures of PVDC-derived nanoporous carbons were characterized by the $N_2$ adsorption technique at 77 K. Heat treatment in an inert atmosphere increased the specific surface area and micropore volume with elevating temperature, while the average micropore width near 0.65 nm was not significantly changed, reflecting the characteristic pore structure of ultramicroporous carbon. Steam activation for PVDC at 873 and 1073 K also yielded ultramicroporosity. On the other hand, the steam activated sample at 1273 K had a wider average micropore width of 1.48 nm, correlating with a supermicropore. The KOH activation increased the micropore volume with elevating temperature, which is accompanied by enlargement of the average micropore width from 0.67 to 1.12 nm. The average pore widths of KOH-activated samples were strongly governed by the activation temperature. We expect that these approaches can be utilized to simply control the porosity of PVDC-derived nanoporous carbons.

• International Journal of Internet, Broadcasting and Communication
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• v.14 no.1
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• pp.136-141
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• 2022

A very complex task in deep learning such as image classification must be solved with the help of neural networks and activation functions. The backpropagation algorithm advances backward from the output layer towards the input layer, the gradients often get smaller and smaller and approach zero which eventually leaves the weights of the initial or lower layers nearly unchanged, as a result, the gradient descent never converges to the optimum. We propose a two-factor non-saturating activation functions known as Bea-Mish for machine learning applications in deep neural networks. Our method uses two factors, beta (𝛽) and alpha (𝛼), to normalize the area below the boundary in the Mish activation function and we regard these elements as Bea. Bea-Mish provide a clear understanding of the behaviors and conditions governing this regularization term can lead to a more principled approach for constructing better performing activation functions. We evaluate Bea-Mish results against Mish and Swish activation functions in various models and data sets. Empirical results show that our approach (Bea-Mish) outperforms native Mish using SqueezeNet backbone with an average precision (AP50val) of 2.51% in CIFAR-10 and top-1accuracy in ResNet-50 on ImageNet-1k. shows an improvement of 1.20%.

• The Journal of Korean Physical Therapy
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• v.22 no.2
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• pp.25-30
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• 2010

Purpose: Behavior and movement are accomplished by voluntary contractions of skeletal muscles. There are three types of muscle contractions: concentric, isometric and eccentric. The aim of our study was to determine whether there is a difference in the cortical activation pattern between concentric contraction and eccentric contraction of the wrist extensor muscle. Methods: Four healthy right-handed volunteers without any previous history of physical or neurological illness were recruited. fMRI scanning was done during 4 repeated blocks of concentric and eccentric exercise of the wrist joint. Subjects exercised for 12 seconds and then rested for 12 seconds before beginning the second set of exercises. To determine the excitability of cortical neurons during exercise, voxel count and intensity index were analyzed. Results: For right hand movements, when concentric contractions of the right wrist were done, only the left primary motor area was activated. In contrast, during eccentric contraction, both the primary motor area and secondary motor area were activated. For left hand movements, both concentric and eccentric contractions induced only the supplementary motor cortex and the contralateral primary motor cortex. Conclusion: During eccentric contractions, both the primary motor area and secondary motor area are activated in ipsilateral and contralateral brain areas. Thus, eccentric contractions require more complex and difficult movements than concentric contractions do.