• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.10 no.2
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• pp.49-52
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• 2006

Theses days, the thickness of Brown tube becomes thinner since the display products are rapidly replaced by PDP, LCD etc. Accordingly, the shadow mask part also become flat. We propose the method of designing the surface with crown since the flat surface is fragile to vibration and shock.

• Honam Mathematical Journal
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• v.34 no.2
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• pp.135-144
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• 2012

falling subalgebra/ideal of a BCK/BCI-algebra is introduced. Relations between falling subalgebras and falling ideals are given. Relations between fuzzy subalgebras/ideals and falling sub-algebras/ideals are provided. A characterization of a falling ideal is established.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.2
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• pp.98-103
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• 2013

In this work, we investigated the enhanced performance of IZO-based TFTs with $HfSiO_x$ gate insulators. Four types of $HfSiO_x$ gate insulators using different diposition powers were deposited by co-sputtering $HfO_2$ and Si target. To simplify the processing sequences, all of the layers composing of TFTs were deposited by rf-magnetron sputtering method using patterned shadow-masks without any intentional heating of substrate and subsequent thermal annealing. The four different $HfSiO_x$ structural properties were investigated x-ray diffraction(XRD), atomic force microscopy(AFM) and also analyzed the electrical characteristics. There were some noticeable differences depending on the composition of the $HfO_2$ and Si combination. The TFT based on $HfSiO_x$ gate insulator with $HfO_2$(100W)-Si(100W) showed the best results with a field effect mobility of 2.0[$cm^2/V{\cdot}s$], a threshold voltage of -0.5[V], an on/off ratio of 5.89E+05 and RMS of 0.26[nm]. This show that the composition of the $HfO_2$ and Si is an important factor in an $HfSiO_x$ insulator. In addition, the effective bonding of $HfO_2$ and Si reduced the defects in the insulator bulk and also improved the interface quality between the channel and the gate insulator.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.2
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• pp.31-41
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• 2014

This paper proposes the configuration of photovoltaic(PV) module considering the environment conditions of the PV system. The PV system is consisted of the series-parallel connection of the PV module. When shadows or changes of the radiation or an electrical characteristic in the solar cell are happened to PV system, the serious power loss will occur. If the PV module connected in series has the shadows, the output current is restricted to current of shaded PV module. Also if shadow is occurred to the parallel connection PV module, the output voltage is limited to voltage of shaded PV module. These problems are caused power loss. Therefore, this paper proposes the method that makes the output power of the PV module equalize by reconfiguration of PV module using the switching considering these environment conditions. A validity of the method proposed in this paper proves through comparing with performance of conventional PV module.

• Korean Journal of Plant Taxonomy
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• v.53 no.2
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• pp.166-169
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• 2023

Carex brevispicula (Cyperaceae) is endemic to Korea and is characterized by constricted achenes, short lateral spikes, and awned staminate and pistillate scales. The species classified in sect. Mitratae occurs throughout South Korea, perennating on mountains and/or rocky slopes under half shadow conditions. Meiotic chromosomes of the species were examined in this study, in which 33 meiotic cells from seven populations were found to be less than 2 ㎛ long with non-constricted chromosomes (n = 34_II). The stable chromosome number may be related to the narrow geographical distribution and/or distinct achene morphology. Further investigations of the distribution, morphological character variation, and chromosome characteristics should be conducted with closely related taxa to understand the derivation of the species and its endemism in Korea.

• Environmental and Resource Economics Review
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• v.22 no.1
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• pp.77-98
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• 2013

China, the world's largest $CO_2$ producer, is likely to be obligated to reduce greenhouse gas emissions under the post-Kyoto protocol. This paper estimates a Shephard input distance function for the Chinese fossil-fueled power generation sector to measure the shadow price of $CO_2$ emissions, technical efficiency, and indirect Morishima elasticities of substitution between inputs. Empirical results show that, on average, it costs approximately 3.2 US dollars per year to reduce $CO_2$ emissions by one ton over the period 1981-2009. This finding indicates that Chinese power sector is expected to benefit from selling emission permits to other countries such as Korea and Japan, given that our estimate for China is lower than the ones previous literatures estimated for the power sector in these countries. The maximum attainable average $CO_2$ reduction potential amounts to approximately 25 million tons per year by improving technical efficiency. Capital is substitutable with both coal and oil and capital is relatively more readily substituted for these fuels.

• Environmental and Resource Economics Review
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• v.30 no.2
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• pp.325-345
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• 2021

In this paper, we empirically evaluate the potential performance of energy conversion policy and analyze its effects on power generation sector. We first examine the degree of substitutability between energy inputs by measuring the price elasticities of energy demands and then estimate the changes in CO₂ generation when the proportions of nuclear power plants and renewable power generation are increased. The shadow prices of nuclear power and renewable energy are calculated to compare the potential costs of power generation between the two energy sources. We analyze the impacts of the expansion of nuclear power plants and renewable power generation on power supply price. Nuclear and renewable energy were measured to be complementary to each other. The expansion of nuclear power plants has been more effective in reducing CO₂ emissions than increasing renewable power generation. In most years over 2002 to 2016, the impact of nuclear power expansion on the power supply price was generally higher than that of renewable power generation, with relatively large range of fluctuations.

• Environmental and Resource Economics Review
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• v.22 no.3
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• pp.459-479
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• 2013

To assess the feasibility of 'low carbon, sustainable growth' policy pursued of the Chinese government, this paper first measures technical efficiency, $CO_2$ shadow prices, and indirect Morishima elasticity of substitution between capital and energy for 24 of manufacturing sectors in Beijing and Chongqing, in which China launched pilot carbon emissions trading scheme, by estimating the input distance function. Based on these results, then the potential for $CO_2$ reduction, cost savings from emissions trading, and the effectiveness of capital investment in reducing $CO_2$ are compared across industries and provinces. In 2010, manufacturing industries in Beijing and Chongqing could potentially reduce the largest $CO_2$ emissions, amounting 5.2 and 17 million tons, respectively, by achieving 100% technical efficiency. While, on average, Chongqing has a comparative advantage in the cost savings from carbon trading over Beijing, Beijing is more likely to reduce $CO_2$ by expanding capital investment.

• Journal of the Korean Society of Food Culture
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• v.35 no.1
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• pp.28-54
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• 2020

This study aims to investigate the food preservation methods adopted by the Joseon Dynasty, which existed before the 17^th century. A total of 232 food preservation methods were discovered in 25 books, and could be classified by their targeted food types: vegetables (84), sea foods (60), meats (41), fruits (37), and others (10). Depending on the preservation method applied, they are classified as food drying, soaking, mud cellar preservation, and other preservation. Food drying is further classified into 8 sub-types: drying, sun-drying, shadow-drying, wind-drying, dry heat, combined drying, smoking, and others. Soaking could be sub-divided into using salt, ash, dry sand, bran, fermented paste, wet distillers grains, oil, and others. Mud cellar preservation is sub-classified into installing shelf inside the mud cellar, making the mud cellar for food preservation, and making hole or underground tunnel for food preservation. Other food preservation methods include minimizing moisture loss by applying beeswax on a section of the vegetable stem, and cutting the vegetables or fruits with their branches and leaves for food preservation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.9B
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• pp.876-882
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• 2009

In this paper, we propose a sub-cell coverage control algorithm for enhancement of the cell throughput in OFDMA based relay systems. Relay station (RS) is exploited for improved quality of the received signal in cellular communication systems, especially in shadow areas. However, since a RS requires additional radio resource consumption for the link between the base station (BS) and the RS, we have to carefully control the coverage areas if a mobile station (MS) is serviced via the BS or the RS considering the cell throughput. We consider radio resource reuse as well for the sub-cell coverage configuration by applying various reuse patterns between RSs. We also consider a time varying system by adaptively changing the threshold for coverage depending on the MSs' traffic in the cell. We initially determine the sub-cell coverage of the system depending on the ratio of received signal-interference-noise-ratio (SINR) of the MS from the BS and RSs, respectively. Then, the "sub-cell coverage threshold" varies based on the "effective transmitted bits per sub-channel" with time. Simulation result shows that the proposed "time varying coverage control algorithm" leads to throughput improvement compared to the fixed sub-cell coverage configuration.