• Journal of the Korean Mathematical Society
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• v.39 no.6
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• pp.881-898
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• 2002

Our aim in this paper is to introduce a generalization of some notions in homological algebra. We define the concepts of chain U-complex, U-homology, chain (U, U')-map, chain (U, U')-homotopy and $\mu$-functor. We also obtain some interesting results. We use these results to find a generalization of Lambek Lemma, Snake Lemma, Connecting Homomorphism and Exact Triangle.

• Journal of Korean Society for Geospatial Information Science
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• v.23 no.2
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• pp.49-58
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• 2015

Up to the present point in time, the level diagnosis system for urban reactivation have utilized various methods for establishment and management in Korea and overseas, such as city competitiveness evaluation, urban decay diagnosis, etc. However, contrary to performing diagnosis and evaluations on general cities in existing studies, it is found to be a very complex and difficult task to perform a diagnosis on the level of U-City due to its unique characteristics. It is difficult to determine the level of a U-City using a level diagnosis system used for general cities because a U-City is comprised of a connection/fusion of various structural elements. Therefore, in order to perform a systematic diagnosis of a U-City, it is necessary to primarily observe the structural characteristics of a U-city to derive a diagnosis system based on the relativity between each structural element. This study aims to propose a directivity of a U-City level diagnosis system in comprehensive consideration of various elements, such as the objective of a U-City, as well as the structural elements that compose a U-City based on the definitions prescribed in U-City legislations, including ubiquitous city planning, ubiquitous city infrastructure, ubiquitous city technology, services, etc. The results of this study are expected to provide a resolution for the regional quality differences of U-Cities, and also establish a stepping-stone for the realization of U-Cities with high degree of completion.

• Information Systems Review
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• v.11 no.2
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• pp.23-44
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• 2009

U-Services are inevitably essential for the realization of u-Cities. Most local governments in Korea have expressed much interest in introducing u-Cites and related u-Services. Since researchers anticipate that developing u-Cities will produce economic effects, the Korea government has support local governments to develop u-Cities and necessary u-Services. However, the technology issues have been dominiated in the field of U-City services and most of the U-City services do not reflects all the complicated and pluralistic sides of environment, which are caused by future uncertainties in developing u-Cites. For the purpose of addressing the above uncertainties, this paper attempts to develop the possible scenarios for U-City services through a scenario planning approach. A focus group interview and survey with professionals in the field of planning u-Cities was performed to identify these uncertainties. Then, in order to investigate the validity of the scenario planning methodology, the u-Service "u-Water purity monitoring" is adopted. After considering the relevant issues, we developed two possible scenarios: a mutual linkage service among u-Service related organization and a cooperating and coordinating service among local governments. On the basis of these scenarios, the strategies for potential U-City services are formulated. Various participants in developing U -City services are encouraged to use the scenarios as the foundation of predicting future features of u-Cities and developing the framework of the U-City service scenarios effectively.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.5
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• pp.111-118
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• 2020

The U-shaped composite beam used in this study consist of a reinforced concrete structure, a beam steel structure supporting the slab, a reinforced concrete structure, and a U-shaped steel plate. The U-shaped composite beam was developed for the purpose of using it as a parking lot because it is highly constructible and has low floor height and long span. For the improvement of constructivity, the U-shaped composite beam ends are planned with standardized H-shaped steel and connected directly to the columns, and the middle of the U-shaped composite beam consists of U-shaped steel plates folded in U-shaped form using thin steel plates (t=6) instead of H-shaped steel. In the middle of the composite beam, where U-shaped steel plates are located, the depth of U-shaped beam may be planned to be small so as to satisfy the height limit of the parking lot. It is important to grasp the structural performance according to the change of depth because low beam depth is advantageous for the reduction of the floor height, but it is a inhibitor to the structural behaviors of U-shaped composite beam. In addition, since U-shaped composite beams are a mixture of steel frame structures, reinforced concrete structures and U-shaped steel plates, securing unity has a great influence on securing structural performance. Therefore, in this study, a structural experiment was conducted to understand the structural performance according to the depth change for U-shaped composite beam. A total of three specimens were planned, including two specimens that changed the depth using a criteria specimen planned for a general parking lot. The results of the experiment showed that the specimens who planned the depth greatly had better structural performance such as yield strength, maximum strength, and energy than the standard specimen.

• ALGAE
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• v.34 no.4
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• pp.253-266
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• 2019

Several species classified to the genus Ulva are primarily responsible for causing green tides all over the world. For almost two decades, green tides have been resulted in numerous ecological problems along the eastern coast of Jeju Island, Korea. In order to characterize the species of Ulva responsible for causing the massive blooms on Jeju Island, we conducted DNA barcoding of tufA and rbcL sequences on 183 specimens of Ulva from eight sites on Jeju Island. The concatenated analysis identified five bloom-forming species: U. australis, U. lactuca, U. laetevirens, U. ohnoi and a novel species, U. pseudo-ohnoi sp. nov. Among them, U. australis, U. lactuca, and U. laetevirens caused to the blooms coming mainly from the substratum. U. ohnoi and U. pseudo-ohnoi sp. nov. were causative the free-floating blooms. Four species, except U. australis, are characterized by marginal teeth. A novel species, U. pseudo-ohnoi sp. nov., is clearly diverged from the U. lactuca, U. laetevirens, and U. ohnoi clade in the concatenated maximum likelihood analysis. Accurate species delimitation will contribute to a management of massive Ulva blooms based on this more comprehensive knowledge.

• The Journal of the Korea Contents Association
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• v.9 no.2
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• pp.326-338
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• 2009

In this paper, we argue that characteristics of ubiquitous business are different from those of e-business or m-business. We have developed a u-business model development framework incorporating the concept of value co-creation experiences, which is a core of the ubiquitous business paradigm. The framework of u-business model development presented in this paper consists of eight steps such as defining of domain, discovery of opportunity nucleus, defining of potential co-creation experience environment, deriving candidates of u-business services, selecting u-business killer services, defining value propositions of u-business killer services, defining u-business killer service offerings, and drawing a resource map of u-business killer services. The proposed u-business model development framework offers useful guidelines for practitioners to develop successful u-business models under a ubiquitous business paradigm.

• Journal of Korean Society of Transportation
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• v.27 no.3
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• pp.39-47
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• 2009

Currently, the minimum breadth as a point available for U-turn setup is designated as "over 9m for one way" in the traffic safety facilities practical manuals, and vehicles allowed to make a U-turn are limited to passenger cars. However, as passenger cars have recently become larger and SUVs (Sports Utility Vehicles) are being popularized, they fail to make a U-turn in one attempt. This causes a traffic jam and a problem with traffic safety. This study proposed, compared, and tested the measured values of actual differences in the turning radius of U-turn by actual cars with estimated values by using PC-Crash, a car accident simulation program. Then, the study forecasted the turning radius of U-turns of Korean passenger cars by using PC-Crash, and proposed appropriate breadth for U-turn setup.

• Journal of applied mathematics & informatics
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• v.25 no.1_2
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• pp.329-337
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• 2007

In the paper, we obtain the existence of positive solutions and establish a corresponding iterative scheme for BVPs $$\{^{\;(\phi_p(u'))'\;+\;q(t)f(t,u)=0,\;0\;<\;t\;<\;1,}_{\;u(0)\;-\;B(u'({\eta}))\;=\;0,\;u'(1)\;=\;0}$$ and $$\{^{\;(\phi_p(u'))'\;+\;q(t)f(t,u)=0,\;0\;<\;t\;<\;1,}_{\;u'(0)\;=\;0,\;u(1)+B(u'(\eta))\;=\;0.}$$. The main tool is the monotone iterative technique. Here, the coefficient q(t) may be singular at t = 0, 1.

• Bulletin of the Korean Mathematical Society
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• v.60 no.6
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• pp.1523-1537
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• 2023

Let R be a commutative ring with identity and S a multiplicative subset of R. First, we introduce and study the u-S-projective dimension and u-S-injective dimension of an R-module, and then explore the u-S-global dimension u-S-gl.dim(R) of a commutative ring R, i.e., the supremum of u-S-projective dimensions of all R-modules. Finally, we investigate u-S-global dimensions of factor rings and polynomial rings.

• Spatial Information Research
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• v.23 no.2
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• pp.83-93
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• 2015

U-Services, which are offered from local governments based on their Ubiquitous City Plans, are only focused on facility and urban management services. Also Citizen oriented U-service is only planned. This study's purpose is to propose the implication for provide of the Citizen oriented U-service comparing with U-Service plan of 'Ubiquitous City Comprehensive Plan' and 'Ubiquitous City Plan' through a network text analysis and word frequency analysis. It was calculated a important keyword that was extracted the service plan contents of the 'Ubiquitous City Comprehensive Plan' and 'Ubiquitous City Plan' of the four local governments. The network text analysis and keyword frequency analysis was performed through derived keyword. Based on the analysis results, awareness of the citizens can be expected to increase about U-City by activating a excavation of Citizen oriented U-service in a variety of sector through additional services and policy of financial support in the next Ubiquitous City Comprehensive Plan.