• The Transactions of the Korean Institute of Electrical Engineers C
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• v.50 no.10
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• pp.479-488
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• 2001

The effects of accelerated Ultraviolet (UV) radiation on High temperature vulcanized (HTV), Room temperature vulcanized (RTV) silicone rubber and two types of ethylene propylene diene terpolymer (EPDM) used for composite insulator were inverstigated by hydrophobicity class (HC), surface voltage decay after corona charging, SEM-EDS, FTIR and XPS. The contact angle in two kinds of silicone rubber was scarcely change, but EPDM occurred to the loss of hydrophobicity followed by surface cracking and chalking. The surface voltage decay on UV-treated silicone rubber and EPDM showed a different decay trend with UV treatment. EDS and XPS analysis indicated that the oxygen content increased with UV treatment time in all samples. For silicone rubber, the oxidized groups of inorganic silica-like structure increased with UV treatment time. The oxidized carbon of C=0, O=C-O in EPDM increased. These oxidized surface for each material had different electrostatic characteristics, so deposited charges were expected to have different impacts on their surface hydrophobicity. The degradation mechanism based on our results was discussed.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.50 no.10
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• pp.494-499
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• 2001

The effects of accelerated Ultraviolet (UV) radiation on High temperature vulcanized (HTV), Room temperature vulcanized (RTV) silicone rubber and two types of ethylene propylene diene terpolymer (EPDM) used for composite insulator were investigated by hydrophobicity class (HC), surface voltage decay after corona charging, SEM-ES, FTIR and XPS. The contact angle in two kinds of silicone rubber was scarcely change, but EPDM occurred to the loss of hydrophobicity followed by surface cracking and chalking. The surface voltage decay on UV-treated silicone rubber and EPDM showed a different decay trend with UV treatment. EDS and XPS analysis indicated that the oxygen content increased with UV treatment time in all samples. For silicone rubber, the oxidized groups of inorganic silica-like structure increased with UV treatment time. The oxidized carbon of C=O, O=C-O in EPDM increased. These oxidized surface for each material had different electrostatic characteristics, so deposited charges were expected to have different impacts on their surface hydrophobicity. The degradation mechanism based on our results was discussed.

• Journal of the Korean Society of Safety
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• v.13 no.4
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• pp.230-239
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• 1998

Though limited, Model Human Processor (MHP) has been used to explain the complex users' behaviors during human-computer interactions in a simplified manner. MHP consists of perceptual, cognitive and motor systems, each with processors and memories interacting with each other in serial or parallel mode. The important parameters of memory include the storage capacity, the decay time, and the code type of a memorized item. The important parameter of a processor is the cycle time. Using these features of the model, this study developed a computerized cognitive process simulator to predict the cognitive process time of a class match task process. An experimental validity test result showed that the mean prediction time for cognitive process of the class match task simulated 50 times by the simulator was consistent with the mean cognitive process time of the same task performed by 37 subjects. Animation of the data flow during the class match task simulation will help understand the invisible human cognitive process.

• Journal of the Korean Operations Research and Management Science Society
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• v.38 no.1
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• pp.139-152
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• 2013

The purpose of this study is to claim the validity of tuning the architecture of neural network models for multi-class classification. A neural network model for multi-class classification is basically constructed by building a series of neural network models for binary classification. Building a neural network model, we are required to set the values of parameters such as number of hidden nodes and weight decay parameter in advance, which draws special attention as the performance of the model can be quite different by the values of the parameters. For better performance of the model, it is absolutely necessary to have a prior process of tuning the parameters every time the neural network model is built. Nonetheless, previous studies have not mentioned the necessity of the tuning process or proved its validity. In this study, we claim that we should tune the parameters every time we build the neural network model for multi-class classification. Through empirical analysis using wine data, we show that the performance of the model with the tuned parameters is superior to those of untuned models.

• 한국생태학회:학술대회논문집
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• 2002.08a
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• pp.127-131
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• 2002

In order to elucidate the characteristics of standing crop biomass, production and nutrient content of dead bole in mature ecosystem, we surveyed the dynamics of decaying bole of old-aged deciduous forest in 1993 and 2002 in Kwangnung Experimental Forest Station. In addition, we and estimated annual bole production, water content, wood density and nutrient content and compared the results with that of temperate ecosystem. Total dead wood biomass was estimated to be 5.6ton/ha in 1993 and 17.6ton/ha in 2002. Standing dead tree accounted for a total of 1.1ton/ha in 1993 and 4.8ton/ha in 2002, which was 20% and 27% of the sum of dead bole mass in 1993 and 2002, respectively. Annual production of bole biomass was 1.3 ton/ha/yr. These values fall into the low range of dead wood biomass for the mature temperate ecosystems. Tree species composing standing bole was mainly Quercus and Carpinus trees. This bole species composition resembles alive species composition of this forest. Water content of bole increased as positive logarithmically, but wood density of bole decreased as negative exponentially along with the progress of decay. N, P, Ca and Mg concentrations in decaying boles generally increased with decay, except for K. Annual nutrient input via dead bole is 1.6kg/ha/yr for N, 0.04 kg/ha/yr for P. 1.0 kg/ha/yr for K, 1.7kg/ha/yr for Ca and 0.3 kg/ha/yr for Mg, respectively.

• The Korean Journal of Ecology
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• v.25 no.4
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• pp.261-265
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• 2002

In order to elucidate the characteristics of standing crop biomass, production and nutrient content of dead bole in mature ecosystem, we surveyed the dynamics of decaying bole of old-aged deciduous forest in 1993 and 2002 in Kwangnung Experimetal Forest Station. In addition, we and estimated annual bole production, water content, wood density and nutrient content and compared the results with that of temperate ecosystem. Total dead wood biomass was estimated to be 5.6ton/ha in 1993 and 17.6 ton/ha in 2002. Standing dead tree accounted for a total of 1.1 ton/ha in 1993 and 4.8 ton/ha in 2002, which was 20% and 27$\%$ of the sum of dead bole mass in 1993 and 2002, respectively. Annual production of bole biomass was 1.3 ton/ha/yr. These values fall into the low range of dead wood biomass for the mature temperate ecosystems. Tree species composing standing bole was mainly Quercus and Carpinus trees. This bole species composition resembles alive species composition of this forest. Water content of bole increased as positive logarithmically, but wood density of bole decreased as negative exponentially along with the progress of decay. N, P, Ca and Mg concentrations in decaying boles generally increased with decay, except for K. Annual nutrient input via dead bole is 1.6 kg/ha/yr for N, 0.04 kg/ha/yr for P, 1.0 kg/ha/yr for K, 1.7 kg/ha/yr for Ca and 0.3 kg/ha/yr for Mg, respectively.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.24 no.6
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• pp.397-404
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• 1991

The steady state and decay characteristics of primary fluorescenece of phytoplanktons including Cyanophyceae and Cryptophyceae were investigated in vivo. At 580-640 nm region, fluorescence emission spectra were obtained from all algae examined. The observed fluorescence emission maxima were similiar$(\pm3\;nm)$ except Synechocorcus sp. (SYN). Considered $\lambda_{max}$ of emission spectra of phycobiliproteins and the excitation spectra with $\lambda_{max}=540-560nm$, it seems to be originated from biliproteins. Fluorescence lifetimes $(\tau)$ and decay curves were compared with standard solution of candidate organic compounds, b-phycoerythrin. The $\tau$ values obtained for phytoplankton with $\lambda_{max}=580nm$ were different depending upon the species of algae. The observed $\tau$ values were ranged from 1.39 ns to 1.95 ns. These are considerably shorter than $\tau(3.23\;us)$ for standard solution of b-phycoerythrin. The reduction of $\tau$ for phycoerythrin in vivo seems to be originated from effective energy transfer system between Chl. a and phycobiliprotein in intact cell. There are subtantial differences in fluorsecence spectra and lifetimes at the class level. At the species level, differences seems to be much smaller. The result of experiment suggests that measurement of fluorescence lifetimes may be helpful in the rapid characterization of algae. Direct application will likely be found in combination with the measurement of other luminescence parameters.

• Bulletin of the Korean Mathematical Society
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• v.50 no.3
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• pp.839-865
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• 2013

We deal with the existence of positive radial solutions concentrating on spheres for the following class of elliptic system $$\large(S) \hfill{400} \{\array{-{\varepsilon}^2{\Delta}u+V_1(x)u=K(x)Q_u(u,v)\;in\;\mathbb{R}^N,\\-{\varepsilon}^2{\Delta}v+V_2(x)v=K(x)Q_v(u,v)\;in\;\mathbb{R}^N,\\u,v{\in}W^{1,2}(\mathbb{R}^N),\;u,v&gt;0\;in\;\mathbb{R}^N,}$$ where ${\varepsilon}$ is a small positive parameter; $V_1$, $V_2{\in}C^0(\mathbb{R}^N,[0,{\infty}))$ and $K{\in}C^0(\mathbb{R}^N,[0,{\infty}))$ are radially symmetric potentials; Q is a $(p+1)$-homogeneous function and p is subcritical, that is, 1 < $p$ < $2^*-1$, where $2^*=2N/(N-2)$ is the critical Sobolev exponent for $N{\geq}3$.

• Journal of the Korean Society of Propulsion Engineers
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• v.19 no.3
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• pp.1-8
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• 2015

A ground hot-firing test(HFT) was accomplished to draw a correlation between the pressure oscillation intensity of combustion chamber and thrust response characteristics in a 70 N-class hydrazine thruster which has been developed recently. Monopropellant grade hydrazine was adopted as a propellant for the HFT, and combustion-chamber characteristic length, propellant injection pressure were applied as test parameters. It was confirmed that the decrease of thrust-chamber diameter and injection pressure augmented the pressure oscillation of stagnation chamber in the test condition specified, and the oscillation hampered the pulse response performance of test models.

• The Journal of the Convergence on Culture Technology
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• v.10 no.2
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• pp.323-331
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• 2024

The concept of 'Han' is a psychological characteristic formed by Koreans through long-lasting national hardships. It has deeply influenced every Korean as a form of collective unconscious and has merged with various forms of art over time. Director Bong Joon-ho's works, rich in social consciousness, symbolically visualize sensitive issues like social class, presenting harsh satire on class oppression. His movies continuously emphasize human desires, the homogeneity of good and evil, insurmountable class barriers, and moral decay caused by desires. They produce a wealth of symbols filled with layers and power dynamics. Bong Joon-ho dramatically portrays and directs various forms of symbols. The metaphorical symbols in his movies provide a unique research value for delving into the deeper meanings of the films.This study examines the theme of 'class Han' in six of Bong Joon-ho's films, exploring the 'Han culture' of Korea. It applies semiotic concepts by categorizing into character and non-character symbols for an in-depth analysis of the films. The representative works from the late 1990s to the late 2010s articulate the class layers of the 'visible' and the 'invisible' through a blend of realism and surrealism. The study analyzes Bong Joon-ho's films in the sequence of 'satire-exposure-hope', examining the culturally critical nature of 'Han culture' on class and its psychological and cultural impact on the general public.