• Journal of Korean Biological Nursing Science
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• 제22권2호
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• pp.111-118
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• 2020

Purpose: The purpose of this study was to understand the impact of long- and short-term energy drinks on anxiety-like, depressionlike, and cognitive behavior in adolescent rats. Methods: Adolescent rats (age six weeks) were randomly classified into a control group (CON), a long-term administration group (LT), and a short-term administration group (ST). The LT group was orally administered 1.5 mL/100 g (body weight) of energy drink twice daily for 14 days, the ST group was orally administered for one day, and the control group applied the same amount of normal saline. Later, an open-field test, a forced swim test, novel object recognition test, and an 8-arm radial maze test was conducted to assess the rats' anxiety, depression, and cognitive function. Results: There were different effects in the long- and short-term groups of energy drink administration. In the LT group, anxiety- and depressive-like behavior increased because of increased movement in the side corner and decrease of immobility time. Also, the time to explore novel objects decreased, and the number of correct responses was reduced, indicating a learning and memory function disorder. However, the ST group was not different from the control group. Conclusion: These results indicate that long-term consumption of energy drinks can increase anxiety-like, depression-like behavior, and this can lead to decrease in learning and memory functions. Thus, nurse and health care providers should understand the impact of energy drink consumption in adolescence to provide appropriate practices and education.

• International Journal of Computer Science & Network Security
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• 제21권2호
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• pp.77-87
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• 2021

In this study, a novel improved second order Radial Basis Function Neural Network based method with excellent scheduling capabilities is used for the dynamic prediction of short and long-term energy required applications. The effectiveness and the reliability of the algorithm are evaluated using training operations with New England-ISO database. The dynamic prediction algorithm is implemented in Matlab and the computation of mean absolute error and mean absolute percent error, and training time for the forecasted load, are determined. The results show the impact of temperature and other input parameters on the accuracy of solar Photovoltaic load forecasting. The mean absolute percent error is found to be between 1% to 3% and the training time is evaluated from 3s to 10s. The results are also compared with the previous studies, which show that this new method predicts short and long-term load better than sigmoidal neural network and bagged regression trees. The forecasted energy is found to be the nearest to the correct values as given by England ISO database, which shows that the method can be used reliably for short and long-term load forecasting of any electrical system.

• 전기학회논문지
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• 제62권8호
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• pp.1066-1073
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• 2013

This paper illustrates newly an outage cost impact index function(OCIIF). The assessment of the OCIIF is described using the Web Based Online Real-time Outage Cost Assessment and Information System(WOROCAIS) for power system outage cost assessment in Korea. The proposed OCIIF is not absolute but relative outage cost impact index function in view point of outage time using web based survey method for outage cost assessment. While conventional methodology does not consider short time outage cost assessment, the proposed OCIIF reflects short time outage. SCOF(Sector Customer Outage Function) in stead of the traditional SCDF(Sector Customer Damage Function) is defined and proposed newly in this paper. Based the SCOF, AVLL(Average Value of Loss Load) is newly proposed. The OCIIF is demonstrated by WOROCAIS in case study around 2,000 sample data surveyed by KEPCO in South Korea in recent.

• 에너지공학
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• 제25권2호
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• pp.37-44
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• 2016

2차 에너지인 전력은 다양한 연료를 발전원으로 하고 있기 때문에, 전력에 대한 수요는 에너지 각 부문에 적지 않은 영향을 미친다. 이에 본 논문에서는 전력수요함수를 추정하여 가격탄력성 및 소득탄력성에 대한 정량적 정보를 도출하고자 한다. 이를 위해 1991년부터 2014년까지의 연간 시계열 자료를 이용하되, 탄력성을 단기와 장기를 구분하여 추정할 수 있는 내생시차변수모형을 적용한다. 종속변수로는 연간 전력수요, 독립변수로는 상수항, 전력실질가격, 실질 국내총생산의 3가지를 이용한다. 분석결과 단기 가격탄력성 및 소득탄력성은 각각 -0.142 및 0.866으로 추정되었으며 유의수준 5%에서 통계적으로 유의하다. 즉 전력수요는 단기적인 관점에서 가격 변화에 대해 비탄력적임과 동시에 소득 변화에 대해서도 비탄력적이다. 장기 가격탄력성 및 소득탄력성을 추정한 결과를 살펴보면 각각 -0.210 및 1.287이며 이 값은 유의수준 5%에서 통계적으로 유의하다. 장기적인 관점에서 보더라도 전력수요는 가격 변화에 대해 여전히 비탄력적인 반면에, 소득 변화에 대해서는 전력수요가 탄력적으로 변한다. 따라서 가격정책 위주의 수요관리정책은 단기 및 장기 모두 효과가 제한적이며, 향후 예상되는 소득 증가에 기인하는 전력수요의 증가는 단기보다는 장기에 보다 두드러질 것으로 예상된다.

• 한국분말재료학회지
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• 제17권4호
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• pp.302-311
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• 2010

In this research, the refinement behavior of the coarse magnesium powders fabricated by gas atomization was investigated as a function of milling time using a short duration high-energy ball milling equipment, which produces fine powders by means of an ultra high-energy within a short duration. The microstructure, hardness, and formability of the powders were investigated as a function of milling time using X-ray diffraction, scanning electron microscopy, Vickers micro-hardness tester and magnetic pulsed compaction. The particle morphology of Mg powders changed from spherical particles of feed metals to irregular oval particles, then platetype particles, with increasing milling time. Due to having HCP structure, deformation occurs due to the existence of the easily breakable C-axis perpendicular to the base, resulting in producing plate-type powders. With increasing milling time, the particle size increased until 5 minutes, then decreased gradually reaching a uniform size of about 50 micrometer after 20 minutes. The relative density of the initial power was 98% before milling, and mechanically milled powder was 92~94% with increase milling time (1~5 min) then it increased to 99% after milling for 20 minutes because of the change in particle shapes.

• 천문학논총
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• 제30권2호
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• pp.599-601
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• 2015

The short time scale X-ray variability associated with the accretion disk around compact objects is complex and is vaguely understood. The study of the cross correlation function gives an insight into the energy dependent behavior of the variations and hence connected processes. Using high resolution RXTE data, we investigate the dynamical cross correlation function of an observation of a black hole source XTE J1550-564 in the steep power law state. The cross correlation between soft and hard X- ray energy bands revealed both correlated and anti-correlated delays (${\leq}{\pm}15s$) on a correlation time scale of 50 s. It was noticed that the observed delays were similar to the delays between X-ray and optical/IR bands in other black hole and neutron star sources. We discuss the possible mechanisms/processes to explain the observed delays in the dynamical CCF.

• 한국음향학회지
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• 제23권7호
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• pp.514-520
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• 2004

수중에서 음원의 위치 추정을 위해 적용되어지는 기법으로써 시간지연차 (TDOA : Time Difference Of Arrival) 추정, 빔 형성 기법, 고 분해능 기법 등이 있다. 본 논문에서는 상대적으로 적은 수의 센서를 사용하여 주파수 영역에서 시간 지연차 추정에 사용되는 MCPSP (Modified Cross Power Spectrum Phase) 함수를 이용하였다. 그러나 MCPSP 함수에 기반한 방법은 CW (Continuous Wate) 신호를 대상으로 할 경우 추정 성능이 크게 떨어진다. 이에 본 논문에서는 Pulsed CW신호를 사용하는 수중 음원의 위치를 추정하기 위해 단 구간 (short-time) 에너지 검출을 이용하여 핑(ping)의 경계 영역을 포함하는 세그먼트를 구성하고 이로부터 MCPSP 함수를 구하는 방법을 제안하였다. 제안된 방법의 성능에 대한 이론적인 접근과 함께 다양한 환경 하에서 분석이 이루어졌다.

• 한국인터넷방송통신학회논문지
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• 제13권1호
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• pp.251-258
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• 2013

주행 중인 자동차의 타이어와 노면이 마찰하면서 반복적으로 발생하는 랜덤성 초음파 신호에 대하여 타이어의 손상을 검출하는 방법에 대해 연구하였다. 먼저 단구간 에너지 함수를 도입한 전처리 과정을 통해 랜덤성질을 감소시키고, 랜덤성질의 정규화 표현으로 코히어런스 함수의 평균값을 사용하였다. 코히어런스 임계값을 사용하여 신호의 우성주기를 결정할 수 있는가에 대한 처리한계를 분석하였고, 전력스펙트럼의 최댓값에 대해 -3dB 임계값을 설정함으로써 우성주기를 판별하는 알고리즘을 제안하였다.

• KEPCO Journal on Electric Power and Energy
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• 제6권2호
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• pp.119-122
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• 2020

With recent ESS (Energy Storage System) fire accident, the fault protection performance is becoming more important. However, there has never been any experiments with the protection performance on the faults in the ESS system level. In this study, the effect of AC ground fault and IGBT (Insulated Gate Bipolar mode Transistor) short-circuit failure on MW class ESS was performed experimentally for the first time in the world. First of all, the effect of the AC single line ground fault on battery was analyzed. Moreover, the transient voltage was investigated as a function of the battery capacity and the power level. Finally, the breaking capability and insulation performance of ESS were examined under PCS short-circuit fault condition. Through the tests, it was found that ESS protection system safely blocked the faulty current regardless of the faults, whereas the electronic parts such as IGBT and MC (Magnetic Contactor) were broken by the fault current. Also, the electrical breakdown in ESS resulted from the transient voltage during the protection process.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 제5회 영호남 학술대회 논문집
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• pp.89-92
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• 2003

ITO thin films were deposited by RF-magnetron sputtering method and crystallization behavior of the films with and without external heating as a function of deposition time was examined. X-ray diffraction results indicated an amorphous state of the film when the deposition time is short about 10 min. When the deposition time was increased over 20 min development of crystallization of the films is observed. Because RF-sputtering transfers the high-energy to the growing film by energetic bombardment, it is believed that considerable activation energy for the crystallization of the film has transferred during deposition, which resulted in the crystallization of ITO thin films without external energy supply.