• Journal of Sensor Science and Technology
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• v.16 no.4
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• pp.259-262
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• 2007

This paper describes the electrical characteristics of polycrystalline (poly) 3C-SiC thin film diodes, in which poly 3C-SiC thin films on n-type and p-type Si wafers, respectively, were deposited by APCVD using HMDS, $H_{2}$, and Ar gas at $1150^{\circ}C$ for 3 hr. The schottky diode with Au/poly 3C-SiC/Si (n-type) structure was fabricated. Its threshold voltage ($V_{bi}$), breakdown voltage, thickness of depletion layer, and doping concentration ($N_{D}$) value were measured as 0.84 V, over 140 V, 61 nm, and $2.7{\times}10^{19}cm^{-3}$, respectively. Moreover, for the good ohmic contact, Al/poly 3C-SiC/Si (n-type) structure was annealed at 300, 400, and $500^{\circ}C$, respectively for 30 min under the vacuum condition of $5.0{\times}10^{-6}$ Torr. Finally, the p-n junction diodes fabricated on the poly 3C-Si/Si (p-type) were obtained like characteristics of single 3CSiC p-n junction diode. Therefore, poly 3C-SiC thin film diodes will be suitable for microsensors in conjunction with Si fabrication technology.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.42 no.3
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• pp.357-366
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• 1997

Rice quality is considered to have two general meanings; 1) milling, cooking, and processing quality, which refer to suitability of the grain for a particular end-use; and 2) physical quality, which means cleanliness, soundness, and freedom from foreign materials. Grain type is associated with specific milling, cooking, and processing characteristics. Thus, this experiment was conducted to classify the grain type categories and marketing grades for Korean leading rice varieties. Length: width ratio of brown rice kernel ranged from 1.57 to 2.25 and most of varieties belonged to short grain except Tongil type rice varieties. Mean of length: width ratio of brown rice kernel was 1.77 and coefficient of variance was 4.79％ in short grain type varieties. Grain shape could be further classified into 5 types by length:width ratio of brown rice kernel; 1 type(less than 1.75), 2 type(1.76∼1.80), 3 type(1.81∼1.90), 4 type(1.91∼2.00), and 5 type (greater than 2.00). For 1 and 2 type of varieties, woven wire sieve having 1.7mm openings showed better whole-kernel yields for special marketing grade, and sieve having 2.0mm openings for 3 and 4 type of varieties. Grain type which classified into 5 categories was not associated with physicochemical and cooking characteristics of rice grain, but sensory evaluation of cooked rice showed better score for 1 type varieties in terms of appearance, gloss, flavor, texture, stickiness, and taste.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.12
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• pp.1135-1140
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• 2008

Bismuth-telluride based thin film materials are grown by Metal Organic Chemical Vapor Deposition(MOCVD). A planar type thermoelectric device has been fabricated using p-type $Bi_{0.4}Sb_{1.6}Te_3$ and n-type $Bi_2Te_3$ thin films. Firstly, the p-type thermoelectric element was patterned after growth of $4{\mu}m$ thickness of $Bi_{0.4}Sb_{1.6}Te_3$ layer. Again n-type $Bi_2Te_3$ film was grown onto the patterned p-type thermoelectric film and n-type strips are formed by using selective chemical etchant for $Bi_2Te_3$. The top electrical connector was formed by thermally deposited metal film. The generator consists of 20 pairs of p- and n-type legs. We demonstrate complex structures of different conduction types of thermoelectric element on same substrate by two separate runs of MOCVD with etch-stop layer and selective etchant for n-type thermoelectric material. Device performance was evaluated on a number of thermoelectric devices. To demonstrate power generation, one side of the sample was heated by heating block and the voltage output measured. As expected for a thermoelectric generator, the voltage decreases linearly, while the power output rises to a maximum. The highest estimated power of $1.3{\mu}W$ is obtained for the temperature difference of 45 K. we provide a promising procedure for fabricating thin film thermoelectric generators by using MOCVD grown thermoelectric materials which may have nanostructure with high thermoelectric properties.

• Journal of Environmental Science International
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• v.18 no.10
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• pp.1123-1134
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• 2009

This study was designed to evaluate qualitatively and quantitatively the pollutant compositions, which were emitted from three types of mosquito repellents(MRs)(mat-, liquid-vaporized, and coil-type) by utilizing a 50-L environmental chamber. A qualitative analysis revealed that 42 compounds were detected on the gas chromatography/mass spectrometer system, and that the detection frequency depended upon chemical types. Nine of the 42 compounds exhibited a detection frequency of 100%. Four aromatic compounds(benzene, ethyl benzene, toluene, and xylene) were detected in all test MRs. The concentration equilibriums in the environmental chamber were achieved within 180 min after sample introduction. The coil-type MR represented higher chamber concentrations as compared with the mat- or liquid-vaporized-type MR, with respect to the target compounds except for naphthalene. In particular, the chamber concentrations of ethyl benzene, associated with the use of coil-type MR, were between 0.9 and $65\;mg\;m^{-3}$ whereas those of mat- and liquid-vaporized-type MRs we~e between 0.5 and $2.0\;mg\;m^{-3}$and 0.3 and $1.4\;mg\;m^{-3}$, respectively. However, naphthalene concentrations in the chamber, where a liquid-vaporized-type MR was placed, were measured as between 17.8 and $56.3\;mg\;m^{-3}$, but not detected in the chamber, where a mat- or coil-type MR was placed. The empirical model fitted well with the time-series concentrations in the environmental chamber(in most cases, determination coefficient, $R^2$ ≿ 0.9), thereby suggesting that the model was suitable for testing emissions. In regards to the target compounds except for benzene, although they were emitted from the MRs, health risk from individual exposure to them were estimated not to be significant when comparing exposure levels with no observed adverse exposure levels or lowest observed adverse exposure levels of corresponding compounds. However, it was concluded that the use of MRs could be an important indoor source as regards benzene.

• Journal of the Korean Society of Costume
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• v.62 no.1
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• pp.76-89
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• 2012

This study was performed to offer the basic data for the design of farm shoes. 265 Korean female farmers aging between the 40s to the 80s volunteered for this study and we measured 40 items on each foot with the 3D foot scanner. First, the differences between farmers' feet and non-farmers' feet were analyzed. Farmers' feet were thicker in the instep areas, but had lower arch height than non-farmers' feet. In addition, farmer's feet were tilted to the inside. Next, eight factors were extracted among the 40 measuring items, and the classification criteria of the foot shape was analyzed. The important factors were: size of foot length and volume of ankle, malleolus height and size, volume of the front part of ankle, medial & lateral ball width, and vertical size of foot. Third, three clusters according to the foot shapes were categorized by cluster analysis of eight factor scores. Foot type 1 was medium in foot length, big in thickness, large in lateral ball width, small in toe 1 angle, and tilted to the inside. Foot type 2 was long and slim, and big in toe 5 angle. Foot type 3 was short in foot length, medium in volume of the front part of ankle, large in medial ball width, and big in toe 1 angle. Despite its shortness, foot type 3 was thick and showed severe deformation in toe 1. Lastly, the frequency distributions of the foot types in each age group were analyzed. Female farmers of the forties showed high frequency in type 1 and other age groups showed high frequency in type 2. The older female farmers showed higher frequency of type 3.

• Journal of the Korean Society of Clothing and Textiles
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• v.22 no.3
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• pp.321-332
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• 1998

The purpose of this study is to provide basic data for more functional and more fitting clothing construction. The subjects were college women aged from 18 to 25 in June, 1997. Data were collected by anthropometry and photometry and analyzed by the characteristic of the upper body- The results are as follows: 1. After analyzing direct anthropometric data, 1 have analyzed the data by the characteristic in each somatotype, classified them and I have had 5 groups. Group 1 with middle height and standard type, group 2 with great height and standard type, group 3 with low height and slim type, group 4 with middle height and fat type, and group 5 with low height and a little fat type. 2. After analyzing indirect photometric data, 1 have analyzed them by the characteristic and I have had 4 groups. Group 1 with lean back type, group 2 with sway back type, group 3 with straight type and group 4 with bend forward type. 3. Through the mutual corresponding relation in the 5 groups classified with direct anthropometric measurement and the 4 groups classified with indirect photometric mea- surement, direct-group 1 comes the most corresponding to indirect-group 2, comes second to indirect-group 4, and comes third to indirect-group 1. Direct-group 2 comes the most corresponding to indirect-group 4, direct-group 3 comes the most corresponding to indirect- group 1, direct-group 4 comes the most corresponding to indirect-group 3, and direct-group 5 comes the most corresponding to indirect-group 1.

• Particle and aerosol research
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• v.9 no.2
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• pp.79-87
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• 2013

In this study, the characteristics of turbulent flow and collection efficiency for an one-stage electrostatic precipitator(ESP) with slit type collecting electrode for urban railway underground tunnels were obtained using computational fluid dynamics(CFD) commercial code FLUENT 6.3 and lab-scale experiments. The electrostatic precipitator was operated under high gas velocity(3~12m/s). Five different designs of collecting electrode, flat plate-type and a slit-type of 3mm, 5mm, 7mm and 10mm slit width and four various gas velocity(3, 6, 9, and 12m/s) were used and applied. A standard k-${\varepsilon}$ model in CFD commercial code FLUENT 6.3 was used for flow simulation. The flow simulation results showed that the turbulent intensity of flat plate-type was higher than slit-type under all gas velocity conditions and also the turbulent intensity of flat plate-type was increased continuously, but in case of slit-type was maintained at constant range. And, the turbulent intensity was decreased according to increasing of slit width. The experimental results showed that the collection efficiency of slit-type was higher than flat plate-type under all gas velocity conditions. And, over 6m/s gas velocity condition, the collection efficiency of 5mm and 7mm was highest, when compared to 3mm and 10mm.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.1
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• pp.50-58
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• 2000

Experiments were carried out to obtain the effects of nozzle configuration and jet to jet spacing on the heat transfer characteristics of single line of circular water jets impinging on a constant heat flux plane surface. The nozzle configurations are Cone type, Reverse cone type and Vertical circular type, and the nozzle arrays are single jet(nozzle dia. 8 mm), 1 row of 3 jets and 1 row of 5 jets. Jet velocities ranging from 3m/s to 8m/s were investigated for the nozzle to target plate spacing of 80 mm. For the Cone and Reverse cone type nozzle arrays, the average Nusselt number of 1 row of 5 jets was larger than that of 1 row of 3 jets at Re$_{D}$<45000, but that of 1 row of 3 jets was larger than that of 1 row of 5 jets at $Reo\le45000$. For the Vertical circular type nozzle, however, the average Nusselt number of 1 row of 3 jets was larger than that of 1 row of 5 jets at all jet velocities. In the condition of fixed mass flow rates, the maximum heat transfer augmentation was obtained for 1 row of 5 jets and was over 2 times larger than that of the single jet for all nozzle configurations. The nozzle configurations that produce the maximum average Nusselt number are as follows: For 1 row of 3 jets, the Vertical circular type at $Reo\le45000$ and the Reverse cone type at $Reo\le45000$. But, they are the Reverse cone type at Re$_{D}$<55000 and the Vertical circular type at$Reo\le55000$ for 1 row of 5 jets.

• Journal of the Korea Convergence Society
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• v.10 no.8
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• pp.283-289
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• 2019

The purpose of this study was to classify the elementary school students to latent groups according to the type of mobile phone usage and to verify the relationship with mobile phone dependency. The latent profile analysis was conducted using the first grade panel data of the elementary school in the Korea Children 's Youth Panel in 2016. The results found 3 latent classes of mobile phone usage: family and friend concentration (Type1), family concentration low level (Type2) and essential (Type3). The results of multiple regression analysis for verifying the relationship between mobile phone use type and mobile phone dependency showed a significant effect. The Type 2 showed more dependency than the Type 1, and the Type 1 showed more dependency than the Type 3. These findings provided basis for the guideline of mobile phones use and for proper intervention to prevent mobile phone dependency for elementary school students.

• Honam Mathematical Journal
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• v.37 no.3
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• pp.353-360
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• 2015

In this paper we study some properties related to the Lemperty hyperbolicity of certain Hartogs type domains. Our results for Lempert hyperbolcity are more generalized than proved in [3].