• Journal of Energy Engineering
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• v.23 no.4
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• pp.41-48
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• 2014

Leak of liquid has been categorized conventionally into instantaneous release and continuous release. In this study, the spread of cryogenic liquid due to limited period of release is investigated for the first time to establish a new classification method with recognizing the irrationality of the conventional one. Such physical phenomena are governed by simultaneous equations concerning volume, radius and height of pool of the cryogenic liquid, and major parameters are evaporation rate per unit area, time of release, and spill quantity. The simultaneous governing equations is decoupled to get efficiently perturbation solutions. As the results, for the same spill quantity, in view of release model, combined release model that consists of continuous and consecutive instantaneous model is necessary with small time of release, while continuous model is solely required with large time of release. Also, the combined model is necessary for small spill quantity with the same time of release. These two regimes of release are clearly distinguished using the perturbation solution to provide a clear basis for the new classification of release models.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.3
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• pp.246-252
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• 2014

This study is on the development of 150PS inboard type of compact water jet propulsion system. The water jet is composed of intake, impeller, diffuser, reverse bucket and main shaft. Components of water jet have been manufactured through precision processing after sand casting. Development of water jet propelled engine has been finally completed by processes which are design, production and inspection on each component. The water jet performance characteristics show that 0.29 m3/s of maximum flow rate and 37 m/s of flow velocity have been secured in the ground test pool. Field test was performed by 21ft test ship that water jet propulsion equipment developed in this study was installed. As a result, the weight of hull, engine and other parts of the ship has been almost 1.2 ton and 45 km/h of maximum sailing speed has been recorded with 3700 rpm of engine in the domestic coast test.

• Korean Journal of Environment and Ecology
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• v.21 no.1
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• pp.1-12
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• 2007

Nauralized plants in Ulleungdo were enlisted as 65 taxa, 21 families,49 genera,63 species and 2 varieties by field survey and flora lists of literature cited. Family Compositae covered 27.7% and Family Gramineae, Family Leguminosae and Family Polygonaceae covered 7.7% each. In this study, the nine taxa such as Rumex nipponicus, Trifolium campestre, Oxalis articulata, Anthriscus caucalis, Ipomoea purpurea, Coreopsis Ianceolata, Galinsoga parviflora, Tritonia crocosmaeflora and Festuca arundinacea are added as Nauralized plants in Ulleungdo. Annual plants ratio is 36.9% by life-form spectrum and Europe ratio is 40.0% by origin. The Urbanization Index was 22.0 and the Ratio of Naturalized has increased by flora lists of literature cited each. Ambrosia artemisiifolia var. elatior is growing in Ulleungdo by a plant cause disturbance. Spread prevention and minimization incoming of gardening plants by management plan of naturalized plants might be required. Moreover, it is needed to induce the succession for the recovery of the cut-slope using the native plants.

• KSBB Journal
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• v.22 no.2
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• pp.78-83
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• 2007

In this study, we investigated the biological activity of antioxidant and antibacterial activity of Indigenous Plants, Jeju-Island., which, using methanol were extracted. The reducing activity on the 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radical and $O^{2-}$ and OH radical scavenging potential, in search for antioxidation activities of Indigenous Plants, were sequentially screened. Among the ten plant parts, Prunella vulgaris var. aleutica Fernald. flower had the highest antioxidative activity. 80% Methanol extracts of ten indigenous plants were screened for antibacterial activity 13 fish pathogenic bacteria by agar diffusion method. Among the various 80% Methanol extracts, the Prunella vulgaris var. aleutica Fernald, Gleichenia japonica Spreng, Microlepia marginata (panzer) Christ., Perilla frutescens var. japonica Hara. showed relatively strong antibacterial activities in the order.

• KSBB Journal
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• v.21 no.2
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• pp.164-169
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• 2006

In this study, we investigated the biological activity of antioxidant and antibacterial activity of Indigenous Plants, Jeju-Island., which, using water were extracted. The reducing activity on the 1,1-diphenyl-2-picrylhydrazyl(DPPH) radical and $O^{2-}$ and OH radical scavenging potential, in search for antioxidation activities of Indigenous Plants, were sequentially screened. Among the ten plant parts, Prunella vulgaris var. aleutica Fernald. flower had the highest antioxidative activity. Hot water extracts of ten indigenous plants were screened for antibacterial activity 13 fish pathogenic bacteria by agar diffusion method. Among the various Hot water extracts, the Prunella vulgaris var. aleutica Fernald, Gleichenia japonica Spreng, Microlepia marginata(panzer) Christ., Perilla frutescens var. japonica Hara. showed relatively strong antibacterial activities in the order.

• Journal of Elementary Mathematics Education in Korea
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• v.17 no.3
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• pp.503-522
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• 2013

In the 2009 new curriculum reform, where creativity is the key point, assessment methods for mathematical creativity is recommended. However, lessons for creativity are not carried out well in mathematics classes. One of the reasons for this is the lack of assessment methods for student's creativity and specific instructions on how teachers should evaluate their students using a written test. Therefore, in this paper, we propose a simple way to evaluate student's creativity by differentiating the student's solutions of the posed problems. For validation of the proposed method, we identified the properties of excellent problem solutions cited by both the students group and teachers group. A chi-square test was then carried out to compare any differences in frequency that each of the groups chose as an excellent solution as a result of the student's problem solving

• Korean Journal of Remote Sensing
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• v.26 no.1
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• pp.9-20
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• 2010

The LIDAR data can be efficiently utilized for automatic reconstruction of 3D models of objects on the terrain and the terrain itself. In this paper, we attempted to generate simulated waveforms of FW (Full-Waveform) LIDAR (LIght Detection And Ranging). We performed the geometric modeling of the sensor and objects, and the radiometric modeling of the waveform intensity. First, we compute the origins and directions of the sub-beams by considering the divergence effects of a laser beam. We then searched for the locations at which the sub-beams intersected with the objects, such as ground, buildings and trees. Finally, we generate the individual waveforms of the reflected sub-beams and the waveform of the entire beam by summing the individual ones. With the experimental results, we confirmed the waveforms were reasonably generated, showing the characteristics of the surfaces the beam interacted with.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.21 no.6
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• pp.55-65
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• 2011

Recently, use of cloud computing service is dramatically increasing due to wired and wireless communications network diffusion in a field of high performance Internet technique. Cloud computing is a model for enabling convenient, on-demand network access to a shared pool of configurable computing resources (e.g., networks, servers, storage, applications, and services) that can be rapidly provisioned and released with minimal management effort or service provider interaction. In a view of digital forensic investigation, it is difficult to obtain data from cloud computing service environments. therefore, this paper suggests analysis method of AWS(Amazon Web Service) and Rackspace which take most part in cloud computing service where IaaS formats presented for data acquisition in order to get an evidence.

• Journal of Digital Convergence
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• v.20 no.2
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• pp.91-105
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• 2022

Most of the preceding studies related to Internet Primary banks are studies on laws, regulations, and expected effects of introduction, and studies on financial consumers' intention to switch to financial services are insufficient. Apply to the PPM(Push-Pull-Mooring)theory to find out the factors that influence financial consumers' intention to switch services from commercial banks to Internet Primary banks. A survey was conducted service users, 1st-order and 2nd-order factor analysis were performed using Smart PLS 3.0. As a result, it was confirmed that the Pull, Push and Mooring had a positive (+) effect on the Intention to Switch, and the Mooring, which is a moderating variable, did not have a moderating effect on the Intention to Switch of the Push and the Pull. The scope of application of the PPM theory, which was used in the service conversion research, was extended to Fintech services, and it can provide various practical useful implications, such as the strategy and spread of Internet Primary banks, and it will be used in various studies to study consumer attitudes.

• Journal of Appropriate Technology
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• v.7 no.2
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• pp.216-224
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• 2021

Purpose: Global collaboration to accelerate development and equitable access to COVID-19 tests, treatments, and vaccines was launched with the name of the Access to COVID-19 Tools Accelerator (ACT-A), and this initiative owes its expertise to the lessons learned of the global health organizations. To date, the comprehensive mechanisms and potential effects of the initiative remain largely unknown. Methods: This study reviewed the programs of Gavi, the Global Fund, Unitaid, and ACT-A, which mitigating barriers to greater use of health technology with an analytic framework. Results and conclusion: The study findings are as follows. First, programs to alleviate the absence of necessary technology include the International Finance Facility for Immunization and Covax Facility. Second, Pooled Procurement Mechanism and Accelerated Order Mechanism are examples of mitigating the inability to access technology. Third, programs to overcome reluctance to adopt accessible technology include health system strengthening efforts such as the capacity-building health workforces. Further actions of Korea are needed to collaborate with the initiatives to enhance health outcomes.