• The Transactions of the Korean Institute of Electrical Engineers P
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• v.63 no.1
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• pp.34-39
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• 2014

In cognitive radios, secondary users can use the spectrum exclusively allocated to a primary wireless system if the secondary users detect the spectrum in idle states. Because the secondary users can utilize the idle state of the spectrum, the utilization rate of the spectrum can be improved. The idle states can be detected by using secondary users' sensing schemes. However, the wireless channel environment where secondary users perform the spectrum sensing is not very friendly to secondary users because the signal-to-noise ratio of the received primary signal is very low. Hence, cooperative sensing scheme where more than one secondary user take part in the spectrum sensing is generally used in cognitive radios. In this paper, we investigate the cooperative sensing performance for machine-to-machine communication devices operated by batteries with limited energy. In general, the energy consumed for the spectrum sensing increases as the length of the sensing period and the number of cooperative sensing nodes. Accordingly, even though the total amount of the consumed energy is the same, an energy allocation methodology how to distribute the energy to the sensing period and sensing nodes can achieve the optimum sensing performance, which is numerically analyzed.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2002.11a
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• pp.114-119
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• 2002

In driving situation, driver’s performance can be divided into primary task and secondary task. Many studies of primary task have been in progress, but those of secondary task are not implemented sufficiently. However, the driver’s error is greatly influenced by secondary task. In this study, an experiment was assessed to determine the relationship between the driver's operation time for the secondary task and mental workload due to speed changes in a driving simulation. The time to perform the secondary task was analyzed with Fitts’ Law, and mental workload was analyzed with RNASA-TLX(Revision of NASA-Task Load Index). The results has showed that the higher speed, the weaker the explanation by the use of Fitts' Law and the result of analyzing mental workload using RNASA-TLX was similar to the result of Fitts’ Law.

• Journal of the Korean Society of Propulsion Engineers
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• v.3 no.1
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• pp.1-8
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• 1999

In the present paper an attempt has been made to simulate the secondary injection-primary flow interaction in the conical rocket nozzle and to derive the performance of secondary injection thrust vector control(SITVC) system. Complex three-dimensional flowfield induced by the secondary injection is numerically analyzed by solving unsteady three-dimensional Euler equation with Beam and Warming's implicit approximate factorization method. Emphasized in the present study is the effect of secondary injection such as secondary mass flow rates and the momentum of secondary/primary nozzle flow mass rates upon the gross system performance parameters such as thrust ratio, specific impulse ratio and deflection angle. The results obtained in terms of system performance parameters show that lower secondary mass flow rate is advantageous for to reduce secondary specific impulse loss. It is further found that the nozzle with secondary jet injected downstream and interacting with fast primary flow is preferable for efficient and stable SITVC over the wide range of use with the penalty of side specific impulse loss.

• Educational Technology International
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• v.21 no.1
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• pp.1-29
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• 2020

Despite the existing body of literature focusing on the effects of one-to-one mobile technology integration in teaching and learning, research discussed that the determinants of mobile technology acceptance and use in secondary school settings are still unclear. Hence, this study examined the extent to which determinants influence high school students' behavioral intention to use one-to-one mobile technology for learning. The newly proposed model incorporated three additional constructs beyond those in the unified theory of acceptance and use of technology (UTAUT) model, including computer self-efficacy, attitude toward using technology and computer anxiety, as suggested by recent literature. Data were collected from 247 U.S. Midwestern high school students who participated in an online survey. Using a structural equation modeling approach, this study established construct validity for the nine-construct extended UTAUT model to assess high school students' intention to use mobile technology. The results of structural relations in the proposed model showed that their behavioral intention to use mobile technology was significantly predicted by social influence and attitude toward using technology. Also, their strong behavioral intention and facilitating conditions were associated with frequent use of mobile technology in learning. Discussion, implications, and conclusion were addressed in this study.

• The Journal of Sustainable Design and Educational Environment Research
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• v.2 no.1
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• pp.1-15
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• 2002

New media is an emerging industry sector. It sits at the nexus of what has become a main vehicle of the Knowledge Based Economy. the crossroads where the use of interactive multimedia technology meets the traditional uses of media. The current Education information Act provided school with PC, multimedia labs and connection to internet. Having such a facility in schools encourage teachers and students to use computers more often. Teachers demand for more educational multimedia contents than they can find in the market. Although there are many good contents, teachers find them unfit or inflexible for their curriculum. The purpose of this study is to identify the elements of standard multimedia studio facilities to develop multimedia contents in primary and secondary schools. The result of this study will provide guidelines for schools to facilitate their multimedia studio for teaching and learning activities, and developing contents for effective use of their facilities.

• Journal of The Korean Association For Science Education
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• v.27 no.8
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• pp.755-764
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• 2007

This study examines secondary school science teachers' use of science museums in their teaching and their perception/evaluation/utilization of the educational programs in Korean science museums. We found that teachers do not use science museums in close connection with their formal education; therefore, the students' experiences usually are minimal or are personal experiences. The main reason for this infrequent use of science museums is not because of their insignificant educational effects, but because of the lack of external and administrative support systems. Science teachers want the museums to have structured/organized programs such as science camps or experiments and a lending program which would provide experimental equipment and exhibits relevant to the school science curriculum. 90% of teachers who answered the survey wanted to participate in developing and managing the educational programs of science museums. The educational programs would be used more effectively in relation to formal science learning if the science teachers, who are science education professionals, participated in managing and planning the educational programs of science museums.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.1345-1351
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• 2010

First, In this essay we research about secondary source unit(SIV)180KVA is install on VVVF direct subways for using Filter Capacitor(FC) maintenance & limit of use. Vehicle's extendly use and congestly at load for Catenary voltage and load change about output change and in SIV unit there are important device named GTO Thyristor, Power Transistor Module device become short and it often happen. We analysis the fault cause and there are effects and we know the secondary source unit in filter capacitor FC1~4 input harmonic distortion component's filtering don't do correctly so we study the capacitor extend use for the component change and the outside condition by slow property changed happen and we check before and when its fault, its difficult to measure. Finally, In this research we care for this reason and we study about capacitor maintenance through control and measure ways improvement and capacitor's life spans limit of use.

• Forest Science and Technology
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• v.14 no.4
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• pp.181-191
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• 2018

This study was carried out in the teaching and research forest of the University of Dschang in Belabo, with the aim of analysing land-cover and land-use changes as well as carbon stocks dynamic. The databases used are composed of three Landsat satellite images (5TM of 1984, 7ETM + of 2000 and 8OLI of 2016), enhanced by field missions. Satellite images were processed using ENVI and ArcGIS software. Interview, focus group discussion methods and participatory mapping were used to identify the activities carried out by the local population. An inventory design consisting of four transects was used to measure dendrometric parameters and to identify land-use types. An estimation of carbon stocks in aboveground and underground woody biomass was made using allometric models based on non-destructive method. Dynamic of land-cover showed that the average annual rate of deforestation is 0.48%. The main activities at the base of this change are agriculture, house built-up and logging. Seven types of land-use were identified; adult secondary forests (64.10%), young secondary forests (7.54%), wetlands (7.39%), fallows (3.63%), savannahs (9.59%), cocoa farms (4.28%) and mixed crop farms (3.47%). Adult secondary forests had the highest amount of carbon ($250.75\;t\;C\;ha^{-1}$). This value has decreased by more than 60% for mixed crop farms ($94.67\;t\;C\;ha^{-1}$), showing the impact of agricultural activities on both forest cover and carbon stocks. Agroforestry systems that allow conservation and introduction of woody species should be encouraged as part of a participatory management strategy of this forest.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.2
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• pp.223-229
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• 2023

Seawater batteries are next-generation secondary batteries that use seawater as a cathode. They utilize marine resources to provide competitive prices, high eco-friendliness, and a structure suitable for marine applications. Based on these advantages, pouch types and prismatic types have been studied and developed assuming natural seawater exposure. However, because of the electrical characteristics of the secondary battery, its capacity and internal resistance vary depending on the use environment. These characteristics are not only utilized for predicting the life of a battery but also have a direct effect on the capacity and power suitable for a specific situation. Therefore, the internal resistance was analyzed in this study by measuring the capacity depending on the seawater battery use environment and the state-of-charge-open-circuit-voltage measurement method.

• Journal of the Korea Society of Computer and Information
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• v.29 no.7
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• pp.231-243
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• 2024

As generative artificial intelligence (AI) services become more diversified and widely used, attempts and discussions on their application in education have become active. The purpose of this study is to investigate and analyze general and work-related perceptions, utilization, and needs regarding generative AI in elementary and secondary education. A survey was conducted among teachers and staff in Chungcheongbuk-do, and 934 responses were analyzed. The main research results are as follows: First, their work-related use of generative AI was lower than their general use, and considering the periodic frequency of more than once a month, the rate was much lower. Second, the main expectation when using generative AI in work appears to be improved work efficiency. Third, regarding the use of generative AI for each task, differences in perception of its usefulness were noticeable depending on position and occupation. They generally responded positively to the usefulness of generative AI in processing documents. To facilitate the use of generative AI for work by elementary and secondary teachers and staff, it is necessary to create an environment that promotes its use while ensuring safety against potential side effects. Additionally, requirements and needs should be considered depending on the position and occupation.