• Journal of Korean Society of Forest Science
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• v.112 no.2
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• pp.188-194
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• 2023

This study aimed to derive the basic wood density, one of several carbon emission factors, for carbon accounting of bamboo forests in Korea. Bamboo is mainly distributed in Jeollanam-do and Gyeongsangnam-do provinces, and 101 sample trees were selected for each of the three species (Phyllostachys nigra var. henonis, P. bambusoides, and P. pubescens). The basic wood density derivation used the KS F 2098 method. The measurements showed that the basic wood density was 0.83 g/cm³ for P. nigra var. henonis, 0.81 g/cm³ for P. bambusoides, and 0.72 g/cm³ for P. pubescens. However, the bamboo distribution area in Korea is not very large, and P. pubescens grows in one area only. Therefore, the basic wood density that can be applied to bamboo was 0.79 g/cm³. Evaluation of the uncertainty of the extracted basic wood density showed a very low value of 1.61%, which confirmed the reliability of the basic wood density derived from this analysis. The basic wood density, biomass expansion factor, and root-to-shoot ratio were used to calculate the carbon storage capacity of one bamboo plant and expanded to calculate the capacity for a hectare of bamboo. Carbon storage and absorption of bamboo were calculated by applying a carbon-emission factor, such as the basic wood density. These study results are expected to contribute to the carbon-neutral policy and forest management direction in Korea.

• Journal of the Korean Society of Clothing and Textiles
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• v.34 no.11
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• pp.1798-1811
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• 2010

This research evaluates the changes in the comfort-related properties of high-density fabric, such as moisture permeability and waterproofness, in order to assess the relative importance of laundry conditions for clothing properties after repeated laundering and suggest the best laundering conditions for high-density fabric through the identification of the most influential factor. A commercial high-density fabric was washed 25 times in a drum-type washer using nine different laundry conditions based on profiles derived from a fractional factorial design. To evaluate the changes in the comfort-related properties of the fabric, pore size, air permeability, water vapor transport, water repellency, and water resistance were measured. The comfort-related properties of the fabric deteriorated after repeated laundering by the damaged surface finish; in addition, the damaged surface also changed the pore size. As a result, the water repellency and water resistance decreased. The detergent was the most responsible factor to change the properties among the four factors of detergent, hardness, temperature, and RPM. The best laundering conditions for the fabric was a neutral detergent, soft water of 70ppm, a temperature of $15^{\circ}C$, and 30rpm.

• Journal of IKEEE
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• v.21 no.2
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• pp.123-129
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• 2017

Proton Exchange Membrane Fuel Cell (FEMFC) is a strong candidate for future automobile and power generation because of its high power density, low emission and low operation temperature. The major concerns of the gas diffusion layer (GDL) inside a FEMFC is water management. The GDL is typically comprised of carbon for electrical conductivity and PTFE for Hydrophobicity. In this simulation, GDL flooding was investigated using a simplified approach method of an established equation models(Fick' Law, Darcy, Law, Stefan-Maxwell diffusion). The performance of GDL was shown using result of the inner heat, water density and oxygen density of the cell using model equations. The catalyst layer mode in FEMFC showed results of effectiveness factor, Butler-volmer and hydrogen flux density. These results are interesting because the influence of several factors has been shown and the information will be helpful for fuel cell design.

• Journal of the Korean Institute of Landscape Architecture
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• v.35 no.4
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• pp.40-47
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• 2007

The objective of this study is to analyze the propriety of the Biotope Area Factor's(BAF) application and propose an improvement plan. The BAP system, initially started by Seoul metropolitan city, is being settled in Korea. The BAF originated from the Biotop $Fl{\ddot{a}}chen$ Faktor(BFF) system of Berlin Germany. It was established as part of the Landscape Plan for the ecological function recovery in the high density built-up area with a sense of environmentally friendly urban management. The study compared the BAF's present condition of Ganddong-Gu, Seoul with Seoul's BAF system. Some problems appeared from the system application. Firstly, it may cause ecological damage if the site ranges are more than current BAF system limits. Secondly, the application of the current BAF system has the possibility of general redevelopment, but the partial improvement considering current standards of the high density built-up area's paving section is impossible. Lastly, division of the application object and application type are not divided well. In addition, the Seoul BAF which is currently applied across the board is based on the destruction of the natural area and low density built-up area. Accordingly, to improve these problems requires a complementary system protecting the ecological function prior to the application of the BAF and with restricted application to high density of BAF system built-up area.

• Journal of Electrical Engineering and Technology
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• v.11 no.4
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• pp.939-942
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• 2016

One of the most important characteristic curves of a solar cell is its current density-voltage (J-V) curve under AM1.5G insolation. Solar cell can be considered as a semiconductor diode, so a diode equivalent model was used to estimate its parameters from the J-V curve by numerical simulation. Active layer plays an important role in operation of a solar cell. We investigated the effect thicknesses and defect densities (N_d) of the active layer on the J-V curve. When the active layer thickness was varied (for N_d = 8×10¹⁷ cm^-3) from 800 nm to 100 nm, the reverse saturation current density (J_o) changed from 3.56×10^-5 A/cm² to 9.62×10^-11 A/cm² and its ideality factor (n) changed from 5.28 to 2.02. For a reduced defect density (N_d = 4×10¹⁵ cm^-3), the n remained within 1.45≤n≤1.92 for the same thickness range. A small increase in shunt resistance and almost no change in series resistance were observed in these cells. The low reverse saturation current density (J_o = 9.62×10^-11 A/cm²) and diode ideality factor (n = 2.02 or 1.45) were observed for amorphous silicon based solar cell with 100 nm thick active layer.

• Journal of radiological science and technology
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• v.4 no.1
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• pp.45-53
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• 1981

In examinations of the stomach roentgenography, it is imperative to obtain adequate film density throughout all its different regions. Therefore, it is necessary to use more sophiscated exposure techniques. In order to achieve these purpose, the radiologic technologists must be measured abdominal thickness in variations with patient positions. In consideration of these problem, the author was made an experiment on correction method of kVp and mAs by abdominal thickness in roentgenography of the stomach. The results were summarized as follws: 1. When the patient in erect position, abdominal thickness was the most thickened at the level of 3cm inferior to umbilicus without regard to body habitus and it was the most thickened at the level of 3cm superior to umbilicus in prone and supine position. 2. As a result of measuring film density for stomach, the adequate film density was represented from 0.70 to 2.49 in erect position and $0.28{\sim}1.18$ in supine position, $0.5{\sim}2.45$ in prone position. 3. In order to obtain uniform film density in 1.25, the correction factor for kVp by abdominal thickness was represented average ${\pm}4.5kVp\;per\;{\pm}1cm$ in a fixed 50 mAs, and average ${\pm}3.9kVp\;per\;{\pm}1cm$ in a fixed 100mAs. 4. In order to obtain uniform film density in 1.25, the correction factor for mAs by abdominal thickness was represented average ${\pm}30.9%\;per\;{\pm}1cm$ in a fixed 80 kvp and ${\pm}26.9%\;per\;{\pm}1cm$ in a fixed 100kVp.

• Journal of Advanced Marine Engineering and Technology
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• v.28 no.6
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• pp.993-999
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• 2004

The estimation of fatigue life at the design stage of membrane type LNG tank is very important in order to arrive at feasible and cost effective solutions considering the total lifetime of the tank. In this study, the practical procedure of fatigue life prediction by use of cumulative damage factors based on Miner-Palmgren hypothesis and probability density function has been shown with the corner region of Gaz Transport Membrane type LNG tank being used as an example. In particular the parameters of Weibull distribution that determine the stress spectrum are discussed. The main results obtained from this study are as follows: 1. The recommended value for the shape parameter of Weibull distribution for the LNG tank is 1.1 in case of using the direct calculation method proposed in this study. 2. The calculated fatigue life is influenced by the shape parameter of Weibull distribution and stress block. The safe fatigue design can be achieved by using higher value of shape parameter and the stress blocks divided into more stress blocks.

• Fire Science and Engineering
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• v.16 no.2
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• pp.51-58
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• 2002

For Halon-1301 regulated by Montreal Protocol and $CO_2$as its alternatives, the empirical equations of density, viscosity, and enthalpy were correlated in terms of temperature. They were obtained by regression analysis from the experimental data in the literature. The empirical equation of density was expressed as compressibility factor by the second- order function of temperature. The empirical equation of viscosity was formulated as a power function, and a correction factor was considered to cover the wider range of temperature. Finally, heat capacity as well as enthalpy were well fitted by empirical form of the second-order temperature. The correlation coefficients of the empirical equations in this work were more than 0.99.

• Journal of the Korean Society of Clothing and Textiles
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• v.28 no.11
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• pp.1516-1523
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• 2004

The purpose of this study were to analyze the effect of weft knit structural characteristics on the subjective texture and sensibility. For this, the material was knitted into 8 kinds of weft plain knit fabrics with four kinds of fiber components such as wool, acryl, rayon, and nylon, 3 steps of densities and 3 steps of twist numbers to ply two yarns. The data were analyzed by factor analysis, ANOVA and multidimensional scaling. From factor analysis, subjective textures were categorized as 'bulk/resilience', 'surface/density' and 'soft/drape', and subjective sensibilities were categorized as 'natural/comfortable', 'feminine/elegance' and 'stable/neat' Among the knit structural characteristics, the component of fibers and the density of fabrics were the important factors to give variations in texture and sensibility : In comparison with wool knit of medium density, the knit fabrics of other components and different densities each showed a unique texture and sensibility. But twist number to ply two yams had a few influence on subjective properties. As a result of MDS analysis, the texture and sensibility of plain weft knit fabrics was classified as 'thin-full', 'hard-soft', 'young-old' and 'warm-cool'.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.20 no.3
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• pp.230-238
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• 2013

Purpose: This study was done to identify the relationship among bone mineral density (BMD), body composition and osteoporosis self-efficacy and to identify predictors of BMD in female nursing students. Method: Participants were 154 nursing students. Osteoporosis self-efficacy was determined by a self-report questionnaire. BMD was measured by ultrasound bone densitometry and body composition by a body composition analyzer. Data were collected between April 1 and 27, 2013 and analyzed using descriptive statistics, ANOVA, Scheff$\acute{e}$ test, Pearson correlation coefficient, and multiple regression with SPSS 18.0. Results: Mean BMD at the calcaneus site was $0.58{\pm}1.31$ (T-score). Incidence of osteopenia was 11.7%. Percentage of body fat (PBF)-defined obesity had higher prevalence than body mass index (BMI)-defined obesity. BMD had significant positive correlations with skeletal muscle mass (r=.226, p=.005) and fat free mass (r=.225, p=.005). The factor predicting BMD was skeletal muscle mass with 4.7% of explained variance. Conclusion: Study results indicate that of body composition components, skeletal muscle mass is the prime predicting factor for BMD. Thus to promote healthy bones, it is important to strengthen the muscles using a program, based on balanced development of all muscles.