• 전기학회논문지P
• /
• 제63권1호
• /
• pp.34-39
• /
• 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.

• 한국감성과학회:학술대회논문집
• /
• 한국감성과학회 2002년도 추계학술대회 논문집
• /
• pp.114-119
• /
• 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.

• 한국추진공학회지
• /
• 제3권1호
• /
• pp.1-8
• /
• 1999

풍전압력비와 2차 제트 분사구 위치에 따른 2차분사 추력방향 제어(SITVC: secondary injection thrust vector control) 성능특성 변화를 수치해석하였다. 2차 제트 분사에 의해 간섭된 수축-팽창노즐 내부의 초음속유동장을 대상으로 3차원 비정상 오일러 방정식을 내재적으로 근사인자분해된 Beam과 Warming의 방법을 사용하여 차분하였으며, 2차 분사 제트에 의한 추력비 비추력비 및 전향각에 대한 성능변화를 고찰하였다. 연구결과 측추력과 비추력비는 2차 분사 질량유량에 비래하여 증가하는 반면, 비추력 성능은 감소되어 2차 분사 질량유량이 적을 수록 추력 성능손실이 적어지는 것으로 나타났다. 또한 동일한 전압력비에 대하여 2차 제트 분사위치가 노즐의 하류에 위치할수록 고속기 주유동과의 간섭에 의한 강한 충격파로 인하여 측추력과 측비추력의 증가와 함께 추력방향 제어성능이 향상됨을 알 수 있었다.

• Educational Technology International
• /
• 제21권1호
• /
• pp.1-29
• /
• 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.

• 교육녹색환경연구
• /
• 제2권1호
• /
• pp.1-15
• /
• 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.

• 한국과학교육학회지
• /
• 제27권8호
• /
• pp.755-764
• /
• 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.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2010년도 춘계학술대회 논문집
• /
• pp.1345-1351
• /
• 2010

본 논문에서는 현재 VVVF 직류전동차에 장착되어 있는 보조전원장치(SIV)180KVA용에 사용되는 필터콘덴서(FC) 유지보수 및 사용한도에 관한 연구를 수행하였다. 차량의 장기사용에 따른 내구연한과 혼잡도 부하에 따른 가선전압 변동 및 부하변동에 대해 출력 전압값의 변화와 SIV장치내 중요소자인 GTO Thyristor, Power Transistor Module 소자가 단락되는 현상이 자주 발생되는 등 고장원인을 분석해 본 결과 보조전원 장치내 필터 FC1~4 캐패시터의 입력측 고조파 성분의 필터링이 제대로 되지 못하는 것을 알게 되었으며, 캐패시터의 장기 사용에 따른 성분변화와 외부조건에 의해 천천히 특성변화를 일으킴으로써 사전 점검방법 및 불량 시 측정하기 어렵다는 점을 착안하여 본 연구를 검토하였다. 이를 위하여 본 연구에서는 캐패시터의 유지보수를 통한 관리와 측정방법의 개선점, 캐패시터의 수명 사용한도에 대해 검토하였다.

• Forest Science and Technology
• /
• 제14권4호
• /
• pp.181-191
• /
• 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.

• 해양환경안전학회지
• /
• 제29권2호
• /
• pp.223-229
• /
• 2023

해수이차전지는 해수를 양극으로 사용하는 차세대 이차전지이다, 해양 자원을 사용하여 가격 경쟁력과 높은 친환경성, 그리고 해양 애플리케이션에 적합한 구조를 가진다. 이러한 장점을 기반으로 지속적 연구개발을 통해 자연 해수 노출을 가정한 파우치 타입 및 각형 타입이 개발되어 왔다. 그러나 이차전지는 전기적 특성상 사용 환경에 따라 용량 및 내부 임피던스가 달라진다. 이러한 특성은 전지의 수명 예측에 활용될 뿐만 아니라 활용하고자 하는 상황에 맞는 용량과 출력에 직접적인 영향을 미친다. 따라서 본 논문에서는 해수이차전지의 사용 환경에 따른 용량 측정과 SoC-OCV 측정 방법을 통한 내부 저항을 분석하고자 한다.

• 한국컴퓨터정보학회논문지
• /
• 제29권7호
• /
• pp.231-243
• /
• 2024

생성형 AI 서비스의 다각화로 다양한 분야와 연령대에서 사용됨에 따라, 교육 분야에서도 활용 시도와 논의가 활발해지고 있다. 본 연구에서는 충청북도 지역 초·중등 교직원 934명 대상의 설문 조사를 통해 생성형 AI에 대한 일반적 및 업무 영역에서의 인식과 활용도, 요구 사항을 조사·분석했다. 주요 연구 결과로, 첫째, 교직원의 생성형 AI 활용 경험은 일반적 사용 대비 업무 목적 사용 경험이 적었고, 월 1회 이상의 주기적 빈도를 고려하면 훨씬 적은 비율로 나타났다. 둘째, 생성형 AI의 업무 활용 시 업무 효율 향상에 대한 기대가 가장 높은 것으로 나타났다. 셋째, 직위와 직종에 따라 생성형 AI의 활용 방안별 유용성 인식차가 두드러졌지만, 다양한 문서 처리 도움에 대한 유용성 인식 정도가 공통으로 높은 것으로 나타났다. 초·중등 교직원의 생성형 AI 업무 활용을 위해 생성형 AI 사용 관련 부작용 및 유의점에 대한 안전장치 마련과 촉진 환경 조성 등의 사항에 대한 개선이 필요하고 직위와 직종에 따라 요구 사항과 필요성이 고려되어야 할 것이다.