• New & Renewable Energy
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• v.19 no.4
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• pp.46-52
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• 2023

Methane is the second most emitted greenhouse gas after carbon dioxide. Despite lower emissions than those of carbon dioxide, methane receives significant attention owing to its more than 20-fold higher global warming potential. Consequently, the importance of research on methanotrophic bacteria, microorganisms capable of converting methane gas into high-value materials, is increasingly emphasized. In the case of methanotrophic bacteria, knowledge on episomal plasmids that can be used for genetic engineering remains lacking, which poses significant challenges to the engineering process. The replication origin sequences of natural plasmids within methanotrophic bacteria have been predicted through in silico methods. The basic characteristics of the replication origin, such as a high A/T ratio, repetitive sequences, and proximity to proteins related to replication, have been used as criteria for identifying the replication origin. As a result, a region with a sequence of 18 base pairs repeated eight times could be identified. The putative replication origin sequence thus identified generally takes the form of iterons, but it also possesses unique features such as the length of the gap between iterons and the repetition of identical iteron sequences. This information can be valuable for future design of episomal plasmids applicable to methanotrophs.

• Nuclear Engineering and Technology
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• v.56 no.6
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• pp.1943-1949
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• 2024

This study focuses on the comparative analysis of ABS polymer samples produced using two distinct manufacturing techniques: 3D printing and the sol-gel methods. In the first approach, ABS polymer was augmented with rare earth oxides, Er₂O₃ and Gd₂O₃, in nano powder form and fabricated into test specimens using 3D printing technology. In the second approach, identical samples were prepared via the sol-gel technique involving mold-based fabrication. Elemental content analysis revealed no significant differences between the samples produced by the two methods. The study proceeds to evaluate the gamma-ray shielding, neutron shielding, temperature resistance, and SEM/EDS pictures of ABS samples generated through both techniques. 3D printing method exhibited more favorable results in terms of structure morphology and thermal stability while there is no significant difference for radiation shielding. The results provide insights into the performance and suitability of each production method for radiation shielding applications. This research not only contributes to enhancing radiation shielding technology but also informs the selection of the most appropriate fabrication method for specific applications in nuclear technologies and diagnostic energy range in medical purposes.

• School Mathematics
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• v.16 no.3
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• pp.503-518
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• 2014

This study examines fourth graders engaged in three concrete activities involving sampling from finite populations. The first included a survey of popular foods for school meals. The second had them take samples from a box containing white and black marbles to predict how many white and black marbles were in the box. The final activity required them to predict how many times the Korean letter '가' would appear in a Korean story book. The results show that the participants can experience and notice different ideas related to samples and sampling in different activities. In the first activity, they acknowledged that samples are useful for obtaining the information about populations. A population survey is difficult and is not overly useful. In the second activity, they recognized that samples cannot be identical to their population but that the information from a group of samples is similar to the information of the population. In the last activity, they devised some ideas about random sampling even though the ideas were immature.

• Bulletin of the Korean Mathematical Society
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• v.55 no.3
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• pp.957-965
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• 2018

We study the class $C{\mathcal{V}} ({\Omega})$ of analytic functions f in the unit disk ${\mathbb{D}}=\{z{\in}{\mathbb{C}}$ : ${\mid}z{\mid}$ < 1} of the form $f(z)=z+{\sum}_{n=2}^{\infty}a_nz^n$ satisfying $$1+\frac{zf^{{\prime}{\prime}}(z)}{f^{\prime}(z)}{\in}{\Omega},\;z{\in}{\mathbb{D}}$$, where ${\Omega}$ is a convex and proper subdomain of $\mathbb{C}$ with $1{\in}{\Omega}$. Let ${\phi}_{\Omega}$ be the unique conformal mapping of $\mathbb{D}$ onto ${\Omega}$ with ${\phi}_{\Omega}(0)=1$ and ${\phi}^{\prime}_{\Omega}(0)$ > 0 and $$k_{\Omega}(z)={\displaystyle\smashmargin{2}{\int\nolimits_{0}}^z}{\exp}\({\displaystyle\smashmargin{2}{\int\nolimits_{0}}^t}{\zeta}^{-1}({\phi}_{\Omega}({\zeta})-1)d{\zeta}\)dt$$. Let $z_0,z_1{\in}{\mathbb{D}}$ with $z_0{\neq}z_1$. As the first result in this paper we show that the region of variability $\{{\log}\;f^{\prime}(z_1)-{\log}\;f^{\prime}(z_0)\;:\;f{\in}C{\mathcal{V}}({\Omega})\}$ coincides wth the set $\{{\log}\;k^{\prime}_{\Omega}(z_1z)-{\log}\;k^{\prime}_{\Omega}(z_0z)\;:\;{\mid}z{\mid}{\leq}1\}$. The second result deals with the case when ${\Omega}$ is the right half plane ${\mathbb{H}}=\{{\omega}{\in}{\mathbb{C}}$ : Re ${\omega}$ > 0}. In this case $CV({\Omega})$ is identical with the usual normalized class of convex univalent functions on $\mathbb{D}$. And we derive the sharp upper bound for ${\mid}{\log}\;f^{\prime}(z_1)-{\log}\;f^{\prime}(z_0){\mid}$, $f{\in}C{\mathcal{V}}(\mathbb{H})$. The third result concerns how far two functions in $C{\mathcal{V}}({\Omega})$ are from each other. Furthermore we determine all extremal functions explicitly.

• Korean Management Science Review
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• v.32 no.1
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• pp.83-100
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• 2015

We analyze a duopoly competition when two firms face input cost increases. The objective of this study is to determine the firms' optimal strategy between a price increase and downsizing under conditions of a spatially differentiated market and consumers' diminishing utility on the product size. We develop a theoretical model of two competing firms offering homogenous products using the standard Hotelling model to determine how firms' optimal strategies change when facing input cost increases. In this paper, there are two types of duopoly competitions: symmetric and asymmetric. In the symmetric case, the two firms have the same marginal cost and are producing and selling identical products. In the asymmetric case, the two firms have different marginal costs. The results show that the optimal strategy decision depends on the size of the input cost increase and the cost differences between the two firms. We find that when two firms are asymmetric (i.e., they have different marginal costs), the two firms might choose asymmetric pairs of strategies in equilibrium under certain conditions. When the cost differences between the two firms are sufficiently large and the cost increase is sufficiently small, the cost leader chooses price increase, and the cost-disadvantaged firm chooses downsizing in equilibrium. This asymmetric strategy reduces price competition between two firms, and consumers are better off. When the cost differences between the two firms are sufficiently large, downsizing is the dominant strategy for the cost-disadvantaged firm. The cost-disadvantaged firm finds it more profitable to reduce the product size than to increase its price to reduce price competition, because consumers prefer downsizing to price increases. This paper might be a good starting point for further analytical research in this area.

• Health Policy and Management
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• v.20 no.1
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• pp.19-36
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• 2010

Fee for long-term care insurance in Korea are determined in proportion to resources utilized according to severity rather than based on categorization of beneficiaries in consideration of the characteristics of resource utilization. This adoption is based on the assumption that as beneficiaries of long-term care insurance, characteristically, demands social services rather than needs medical treatments, the characteristics of beneficiaries and the quality of utilized resources are comparatively homogenous. Therefore, the proposition is that the size of resource consumed by beneficiaries in the same grade is identical. However, even in the same grade, the level of utilized resources is different depending on the characteristic of beneficiaries. In this regard, this study is to examine whether there are differences in the volumes of utilized resources depending on the characteristics of beneficiaries even in the same grade. We analyzed time study data for 2003, 2005, 2006 which conducted by the Korea Institute for Health and Social Affairs. To look at differences in the volumes of utilized resources, we identified characteristics of beneficiaries that influence utilized resource volumes and categorized services provided by facilities into the rehabilitation treatment category, the problematic behavior category, and the physical malfunction category. Then, we examined each service in consideration of service difficulty levels and wage weights. The result of examination showed that differences in utilized resource volumes exist in all three grades depending on the characteristics of beneficiaries. Especially, in the first grade with a high level of seriousness, utilized resource volumes were different for those three service categories and the problematic behaviour category considered dementia was found to consume the largest volume of resources. Moreover, there was the inversion phenomenon of utilized resources volumes between the grades. This result indicates that utilized resource volumes are different even in the same grade depending on the characteristics of beneficiaries and it is required to consider case-mix for reflection of the volumes of utilized resources depending on the characteristics of beneficiaries.

• Journal of the Korean Institute of Landscape Architecture
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• v.30 no.2
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• pp.12-22
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• 2002

This study examines the visitors'evaluations of tourism resources in Insa-dong, which the Seoul metropolitan government has improved recently. This study adopted the method of Importance-Performance Analysis by collecting data through questionnaires. A random sampling of visitors to Insa-dong was conducted in June and July,2001. The survey included questions on the physical and psychological components of Insa-dong's tourism resources. In the case of physical components, eight factors(ancient arts shop, art gallery, atelier, calligraphy shop, pottery arts, traditional tea house, antique shop, traditional clothes) out of thirteen were categorized as 'keeping up the good work'. None of the Physical components was shown as 'low priority'or'possible overkill'. In particular, four factors(restaurant, heritage, Korean-style house and alley, traditional cultural festival) need to be impoved most urgently in terms of visitors'satisfaction. Survey results realize them as high priority in importance but low in performance, thereby designated as, 'concentrate here'. An image of the 'street' showed to be high in importance and identical in performance, so can be categorized between'keeping up the good work'and 'concentrate here'. The results show that unusual outdoor spaces and the festivals of Insa-dong have a significant meaning to the visitors. In the case of psychological components, three factors(general atmosphere experience of unusual atmosphere, appropriateness of stroll time) out of seventeen were categorized as 'keeping up the good work'. Ore factor (shopping) was designated as 'low priority'and not found to be 'possible overkill'. Thirteen factors (various events, possibility of various activity, various flood, richness of play, new experience, education cultural inheritance, parking facilities, resting places, green spaces, meeting places, guide map and information, cleanliness of facilities/convenience) need to be improved mast urgently in terms of visitors' fulfillment. They are perceived as areas of 'concentrate here'. This confirms that attractive events are essential for the recent visitor satisfaction. Furthermore, visitors are not satisfied with its amenity and acccss in Insa-dong despite the improvements. In conclusion, positive impressions, both physical and psychological, should be maintained while factors mentioned to be lacking should be prioritized in order of necessity to improve the image of Insa-dong and solutions need to be found and implemented. The results of this study would be helpful in the planning and management of nsa-dong considering the visitors'requirements.

• Korean Journal of Veterinary Research
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• v.49 no.4
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• pp.291-295
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• 2009

A dead stray cat was necropsied for zoonotic feline disease monitoring. Grossly, there were no specific lesions. Major microscopic lesions included lymphocytic meningoencephalitis, malacia, and tissue cysts in the cerebral and cerebellar cortex. The size and shape of tissue cysts were identical to those of Apicomplexa including Toxoplasma (T.) gondii. Bradyzoites in the tissue cyst were strongly positive for T. gondii by immunohistochemistry. Electron microscopy revealed that bradyzoites within the tissue cyst were similar to the morphological features of T. gondii. Fresh tissue samples were examined by a polymerase chain reaction assay and resulted in a specific band of T. gondii only in the brain. Based on the results, this case was diagnosed as toxoplasmosis. This is the first case of toxoplasmic meningoencephalitis in a cat in Korea.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.2
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• pp.331-341
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• 1993

The propagating crack problems under dynamic antiplane mode in orthotropic material is studied in this paper. To analyze the dynamic fracture problems by theoretical method or experimental method in orthotropic material, it is important to know the dynamic stress intensity factor in the vicinity of crack tip. Therefore the dynamic stress field and dynamic displacement field with dynamic stress intensity factor of orthotropic material in mode III were derived. When the crack propagation speed approachs to zero, the dynamic stress components and dynamic displacement components derived in this paper are identical to the those of static state. In addition, the relationships between dynamic stress intensity factor and dynamic energy release rate are determined by using the concept of crack closure energy with the dynamic stresses and dynamic displacements derived in this paper. Finally, the characteristics of crack propagation are studied with the properties of orthotropic material and crack speed. The variation of angle .alpha. between fiber direction and crack propagating direction and crack propagation speed fairly effect on stress component and displacement component in crack tip. The influence of crack propagation speed on the speed on the stress and displacement is greater in the case of .alpha.=90.deg. than in the case of .alpha.=0.deg. and the faster the crack propagation speed, the greater the stress value and displacement value.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.11
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• pp.1407-1413
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• 2011

In this paper, the structural design for composite blade was performed and full scale structural test was conducted to verify the structural design and integrity of composite blade. Firstly, FE analysis was performed using commercial software ABAQUS under conditions of rated wind speed and Case H in IEC 61400-2. Lay-up sequence and ply thickness were designed based on FE results. And to verify the structural design, full scale structural test was conducted according to IEC 61400-2 under identical loading conditions of FE analysis. Finally, the force-deflection and local strain behavior of composite blade were evaluated.