• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.1
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• pp.666-670
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• 2015

This paper presents radiation pattern reconfigurable antenna for Fitbit Flex wristband which detects vital signal. Also, the paper presents Specific Absorption Rate (SAR) from the loop-dipole radiation pattern reconfigurable antenna based on the position of human body. The proposed loop-dipole radiation pattern reconfigurable antenna produces two opposite side direction radiation pattern using two RF switches. The resonant frequency of the radiation pattern reconfigurable antenna is Bluetooth communication bandwidth (2.4 - 2.485 GHz) and the maximum gain of the proposed antenna is 1.96 dBi. The proposed antenna satisfied the standard SAR value of 1.6 W/kg in 1 g tissue of the human body when the Bluetooth communication input average power of 0.04 W is excited to five parts of human body (head, chest, stomach, back, wrist). The maximum SAR value of in this simulation is presented in the part of head.

• Korean Journal of Applied Biomechanics
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• v.16 no.4
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• pp.175-187
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• 2006

The purpose of this study was to find the relationship between Achilles tendon angle, angular velocity from 2D cinematography utilized to easily analyze the functions of shoes, ankle joint moment, knee joint moment, and hip joint moment from 3D cinematography utilized to predict the injury. Also, this study was to provide the optimal standard to analyze the injury related to the shoes. Subjects in this study were 30 university male students and 18 conditions (2 types of running speed, 3 of midsole hardness, 3 of midsole height) were measured using cinematography and force platform. The results were as following. 1) Hip joint abduction moment was effected by many variables such as running speed, midsole height, maximum achilles tendon angle, ground reaction force. 2) Knee joint rotational moment in running was approximately 1/10 - 1/4 times of the injury critical value and eversion moment was approximately 1/4 - 1/2 times of the injury critical value. 3) Ankle joint pronation moment in running was 1/3 - 1/2 times of the injury critical value. 4) Knee joint rotational moment was found to be irrelevant with maximum achilles tendon angle or angular velocity. 5) Pronation from running was thought to be relevant to rather eversion moment activity than rotational moment activity of knee joint. 6) Plantar flexion abductor of ankle showed significant relationship with the ground reaction force variable. 7) When the loading rate for ground reaction force in passive region increased, extensor tended to be exposed to the injury. Main variables in biomechanical analysis of shoes were impact absorption and pronation. Among these variables, pronation factor was reported to be relevant with knee injury from long duration exercise. Achilles tendon angle factor was utilized frequently to evaluate this. However, as the results of this study showed, the relationship between these variables and injury relating variable of knee moment was so important. Studies without consideration on this finding should be reconsidered and reconfirmed.

• Korean Chemical Engineering Research
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• v.49 no.1
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• pp.95-100
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• 2011

During the development of low band-gap organic materials(p-type semiconducting organic compounds) for organic solar cells, an oligomer consisting of 2,5-dioctyloxyphenylene(OP), 3-hexylthiophene(HT), and 2,3-dimethylthieno[ 3,4-b]pyrazine(TP) as repeat units, oligo(OP-HT-TP), was synthesized. The oligomer was amorphous in nature in the temperature range studied, and well soluble in common organic solvents such as chloroform. The maximum absorption wavelength was 716 nm in solid state. The band-gap and HOMO/LUMO energy levels of oligo(OP-HT-TP) were measured to be 1.20 eV and -5.27/4.04 eV, respectively. However, the absorbance of the oligomer at maximum absorption wavelength was less than one fifth of that of poly(3-hexylthiophene) which has been most frequently used in fabrication of organic solar cells.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.39 no.2 s.120
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• pp.60-67
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• 2007

To investigate the dying properties of the extracts from different parts of Neolitsea sericea Koidz on Hanji, the dye materials were prepared from the extraction methods using $1{\ell}$ of hot water and alkaline solution with 40 g of leaves, bark, and wood each. K/S values and H (V/C) values of the Hanji dyed at different pH, temperature, time, and concentration of extract were determined using a spectrophotometer, and the maximum absorption wavelength of the dyed Hanji was 400 nm. From the analyzed data, the optimum dying conditions were pH 5 of dying solution, $70^{\circ}C$ of dying temperature, 40 minutes of dying time, and 100% of dye concentration. The color of dyed Hanji was Y to YR and color R- and RP-type could also be formed from the different treatment conditions. From the dyeing using mordants, amount of the bound dye materials was high in the pre-mordanted Hanji and in Hanji treated with extracts from the leaves. Also, the amount of the bound dye materials in the pre-mordanted Hanji was higher when aluminum and iron mordant was used rather than other mordants. Not likely with this, amount of the bound dye materials in the post-mordanted Hanji was higher when copper mordant was used. In color, Hanji treated extracts from the leaves appeared as Y-type and ones treated with extracts from bark and wood showed YR-type.

• Journal of the Korean Ceramic Society
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• v.38 no.9
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• pp.794-798
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• 2001

$Y_{2-x}SiO_5:Ce_x^{3+}$(x=0.002∼0.04) phosphors were prepared by sol-gel process, amorphous crystal phase was observed in calcining dry gel at 800$^{\circ}$C, but pure $X_2$ type of type $Y_2SiO_5$ phase appeared from heat treatment above 1000$^{\circ}$C. Light absorption of tye $Y_2SiO_5$ host lattice occurred at 230∼360nm, and light absorption of the $Y_{2-x}SiO_5:Ce_x^{3+}$ phosphors was observed at 300∼400nm in adding $Ce^{3+}$. $Y_{2-x}SiO_5:Ce_x^{3+}$ phosphors showed maximum emission shoulder at 436nm. Maximum CL intensities of $Y_{2-x}SiO_5:Ce_x^{3+}$ were observed in adding 0.025 $Ce^{3+}$ and the phosphor showed x=0.161, y=0.124 in color coordinate of CIE1931.

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.4
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• pp.109-115
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• 2015

High performance fiber reinforced cementitious composite (HPFRCC) can provide high fracture energy absorption as well as high strength with high fiber volume fraction. The increased fracture energy helps resisting high frequency loadings, such as earthquake, impact or blast. This study investigates the flexural performance of slurry infiltrated fiber concrete (SIFCON), one of the important HPFRCC, with respect to varying fiber volume fraction. The maximum fiber volume fraction was 8.0 % and reduced to 6.0% by 0.5% and the maximum volume fraction is obtained by packing fibers with simple tapping by hands. The used fiber was a steel fiber with the length 30 mm and the diameter of 0.5 mm. The flexural strengths were 48.7 MPa at 8.0 % and 22.8 MPa at 6.0 %. The measured flexural strength is much higher compared to other cememtitious composite materials but decreased proportional to the fractions. This result implies that for SIFCON considered herein the reduced amount of steel fibers may affect its flexural performance in a negatively way. The flexural toughness, an index to represent the fracture energy absorption, also decreased with the reduced fiber amount.

• Journal of the Korea Fashion and Costume Design Association
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• v.19 no.1
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• pp.135-145
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• 2017

In order to analysis on color difference of yellow natural dyes, I have dyed cellulose and protein fabrics. The results of experiment have been analysed by wavelength of maximum absorption, amounts of dye uptake, color difference, Hunter's value and Munsell's value. The results from these analyses are as follows : Bud of pagoda tree, Amur cork, and Curcuma showed greenish yellow color, Gardenia Jasminoides showed reddish yellow color. Barberry root showed reddish yellow color with post-mordanting method on cellulose fabric. Moreover, Dupioni silk was dyed in reddish yellow color by Barberry root and Rhubarb. In addition to Chroma index, Gardenia Jasminoides and Curcuma showed clear color overall. However, dyeing rayon and silk by Barberry root, and dyeing silk by Rhubarb showed clear color. Comparing all the results to actual dyed materials, Bud of pagoda tree had small dye uptake, and both ${\Delta}a$ and ${\Delta}b$ value were short which can't recognized the yellow color easily. Dye uptake of Amur cork and Gardenia Jasminoides was small just like Bud of pagoda tree. However, ${\Delta}b$ value order was Gardenia Jasminoides>Amur cork>Bud of pagoda tree. Therefore, Gardenia Jasminoides recognized reddish yellow because of big value of red color and yellow color. In case of Barberry root and Rhubarb which have larger dye uptake, Baberry root recognized yellow color on rayon only, and couldn't recognized yellow color on bleached cotton fabric, ramie, silk, and dupioni silk. Rhubarb recognized yellow color on rayon with pre-mordanting method only, but recognized silk and dupioni silk as brown like color. Moreover, we could not analyze color by dye uptake, Lab, and H(v/c) for Barberry root and Rhubarb. As a result, I think we need to attach color table for the research paper which handled the color of dyeing materials.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.14 no.1
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• pp.8-18
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• 2002

In this paper, wave energy absorption of OWC(oscillating water column) device is analyzed. The analytic model consists of a partially immersed circular vertical cylinder open at its end and an air turbine connected with the air chamber. The boundary value problem is decomposed into scattering problem related to scattering by an incident wave in the absence of a pressure variation and radiation problem describing the flow due to an oscillating pressure in the absence of an incident wave. By invoking the continuity of an air flow inside the chamber, the oscillating pressure in a chamber is derived. With oscillating pressure, the mean power absorbed by OWC device and the capture width are obtained. In numerical calculation, the induced volume flux across the internal free surface of the chamber in the scattering and radiation problem and the maximum capture width are compared with various design parameters such as radius and submergence depth of chamber and wave conditions. The maximum capture width obtained by choosing the optimal value of turbine constant occurs at the first resonant mode (Helmholtz mode) among the natural frequencies of a circular cylinder chamber.

• Journal of the Korean Society of Clothing and Textiles
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• v.27 no.3_4
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• pp.364-372
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• 2003

In this study, the characteristics of catechol tannin and pyrogallol tannin contained in Pteridium aquilinum were analysed by It spectrum. Silk fabrics were dyed with Pteridium aquilinum extracts using various mordants, and their dyeing properties were discussed. Additionally the fastness the water digestion, perspiration liquid digestion and light irradiation were investigated. IR spectrum of catechol tannin showed bands of O-H at $3417cm^{-1}$, C-H at $2930cm^{-1}$, C=0 at $1722cm^{-1}$, C=C at $1644cm^{-1},\;CH_2\;at\;1402cm^{-1}$. And IR spectrum of pyrogallol tannin showed bands of O-H at $3409cm^{-1}$, C-H at $3003cm^{-1}\;and\;2933cm^{-11}$, C=0 at $1701cm^{-1}$, C=C at $1582cm^{-11},\;CH_2\;at\;1410cm^{-1}$, CO at carboxylic acid and carboxylic acid ester at $1287cm^{-1}\;and\;1135cm^{-1}$. The maximum absorption wavelength of the extracts appeared at 270.0nm and 311.5nm. The optimum conditions for dyeing silk fabric with Pteridium aquilinum extracts were $80^{\circ}C$, 60min. Surface color of the silk fabric dyed with Pteridium aquilinum extracts was 2.7Y Surface color of the pre-mordanted fabrics with Al, Cu and Fe were 4.3Y, 2.5Y and 4.7Y, respectively. And Surface color of the post-mordanted fabrics with Al, Cu and Fe were 3.7Y, 2.8Y and 0.2GY. The water fastness and the alkaline perspiration fastness were improved in the Al-mordanted silk fabrics. By acidic and alkaline perspiration treatment, ${\Delta}E of the unmordanted fabrics was lower than hat of pre- and post- mordanted fabrics. Also after 40hour irradiation, ${\Delta}E of the unmordanted fabrics was lower than that of pre- and post- mordanted fabrics.

• Applied Biological Chemistry
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• v.51 no.1
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• pp.6-10
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• 2008

This study was carried out to investigate rheological properties of bread dough by adding hydrocolloids such as arabic gum, pectin and carboxyl methyl cellulose (CMC). 0.2% and 0.5% of each hydrocolloid were added to the dough. Farinograph, pH of dough, extensograph, fermometer and amylograph were analyzed. In farinograph, water absorption rate of dough was increased by adding hydrocolloids and the highest water absorption resulting in 70.8% was shown by adding 0.5% of CMC. Dough development time increased but stability decreased. pH of dough was lowered by adding hydrocolloids and pH of dough with 0.5% of pectin was the lowest. In extensograph, resistance of dough decreased but extensibility increased and R/E value lowered. In fermometer, $CO_2$ gas production increased and dough with 0.2% of CMC showed the largest gas production. In amylograph, initial gelatinization temperature increased by $0.5-1.5^{\circ}C$, but temperature for maximum viscosity was lowered by $1-1.5^{\circ}C$ and maximum viscosity was increased.