• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.129.2-129.2
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• 2011

Knowledge of the detailed solar radiation components are essential for modeling many solar systems. This is particularly the case for applications that concentrate the incident energy to attain high photo-dynamic efficiency achievable only at the higher intensities. In order to estimate the performance of concentrating solar systems, it is necessary to know the intensity of the beam radiation, as only this component can be concentrated. The Korea Institute of Energy Research(KIER) has began collecting detailed solar radiation component data since August, 1988. KIER's component data will be extensively used by solar system users or designers as well as by research institutes.

• Journal of the Korean Solar Energy Society
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• v.27 no.2
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• pp.53-59
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• 2007

Knowledge of the solar radiation components are essential for modeling many solar photovoltaic systems. This is particularly the case for applications that concentrate the incident energy to attain high photo-dynamic efficiency achievable only at the higher intensities. In order to estimate the performance of concentrating PV systems, it is necessary to know the intensity of the beam radiation, as only this component can be concentrated. The Korea Institute of Energy Research(KIER) has began collecting solar radiation component data since August, 1996. KIER's component data will be extensively used by concentrating PV system users or designers as well as by research institutes.

• Journal of Advanced Marine Engineering and Technology
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• v.23 no.4
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• pp.514-522
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• 1999

The laser-induced plasma affects greatly on the results of welding process. moreover selective evaporation loss of alloying elements leads to change in chemical composition of weld metal as well as the mechanical properties of welded joint. this study was undertaken to obtain a fundamental knowledge of pulsed laser welding phenomena especially evaporation mechanism of different aluminum alloys. The intensities of molecular spectra of AlO and MgO were different each other depeding on the power density of a laser beam Under the low power density condition the MgO band spectrum was predominant in intensity while the AlO spectra became much stronger with an increase in the power density. These behaviors have been attributed to the difference in evaporation phenomena of Al and Mg metals with different boiling points and latent heats of vaporization. The time-averaged plasma temperature and electron number density were determined by spectroscopic methods and consequently the obtained temperature was $3,280{\pm}150K$ and the electron number density was $1.85{\times}10^{19}\;l/m^3$.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.934-939
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• 2004

The Korea high-speed rail, based on the French design. It also implements new concept to increase the strength of bridge deck by adding an impact factor (dynamic intensity factor) in static load. In order to assure the dynamic stability, SYSTRA and Jeseph Penzien, a professor in CEC (the US) conducted a dynamic stability review on design phase. Analyzing the review results, they developed design criteria for dynamic behavior. This study deal with operating PSC box GIRDER equipped with measurement equipment or measured data of Seoul $\∼$ Taejeon, P.S.C BOX GIRDER bridge and steel comsition bridge equipped with measurement equipment based on structual knowledge about configuration of measuring sensor, response analysis of structure when train runs was performed by using measured data of PSC box girder to directly compare with design criteria. moreover, the dynamic stability with comparison of high-speed rail construction criteria was reviewed and analyzed based on historical records.

• Wind and Structures
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• v.10 no.3
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• pp.249-268
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• 2007

Past experience indicates that the majority of failures of electrical transmission tower structures occurred during high intensity wind events, such as downbursts. The wind load distribution associated with these localized events is different than the boundary layer wind profile that is typically used in the design of structures. To the best of the authors' knowledge, this study represents the first comprehensive investigation that assesses the effect of varying the downburst parameters on the structural performance of a transmission line structure. The study focuses on a guyed tower structure and is conducted numerically using, as a case study, one of the towers that failed in Manitoba, Canada, during a downburst event in 1996. The study provides an insight about the spatial and time variation of the downburst wind field. It also assesses the variation of the tower members' internal forces with the downburst parameters. Finally, the structural behaviour of the tower under critical downburst configurations is described and is compared to that resulting from the boundary layer normal wind load conditions.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2700-2703
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• 2008

An experiment on bubble-driven flow was performed in order to understand fundamental knowledge of flow structure around a rising bubble in a stagnant fluid. The measurement technique consists of a combination of the three most often used PIV techniques in multiphase flows: PIV with fluorescent tracer particles, the digital phase separation with a masking technique and a shadowgraphy. The key point of the measurement is that the background intensity of a PIV recording can be shifted to a higher level than a bubble region using a shadowgraphy in order to distinguish from fluorescent particles and a bubble as well. Flow fields were measured without an inaccurate analysis around a fluid-bubble interface by using only one camera simply.

• Journal of Power System Engineering
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• v.6 no.4
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• pp.36-42
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• 2002

In the structures of automobiles and ships which have engines for works, the vibration energies generated by the engines are transferred to dissipation parts through the structures which is welded and bolted with beams and plates. The vibration energies generated by resonance frequencies are the reasons of the resonance phenomena. To solve these problems, up to the present, we have studied to avoid the resonance, and add the higher damping characteristics. However, we need to understand the structural energy flows, to design the structures clearly which have the characteristic of welding. The object of this study is to make differences clear in the characteristics of structures which have some welded part on an homogenous flat plate. In this investigation, we study the flows of structural vibration energy experimently, and then, some knowledge for dynamic structural design is obtained.

• Advances in Computational Design
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• v.5 no.1
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• pp.91-109
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• 2020

Over the past few decades, the impact of natural, manmade and natech (natural hazard triggering technological disasters) disasters has been devastating, affecting over 4.4 billion people. In spite of recent technological advances, the increasing frequency and intensity of natural disasters and the escalation of manmade threats is presenting a number of challenges that warrant immediate attention. This paper explores the integration of drones or Unmanned Aerial Vehicles (UAV's) into infrastructure monitoring and post-disaster assessment. Through reviewing some of the recent disasters, effectiveness of utilizing UAV's in different stages of disaster life cycle is demonstrated and needed steps for successful integration of UAV's in infrastructure monitoring, hazard mitigation and post-incident assessment applications are discussed. In addition, some of the challenges associated with implementing UAV's in disaster monitoring, together with research needs to overcome associated knowledge gaps, is presented.

• Journal of Environmental Science International
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• v.30 no.10
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• pp.863-877
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• 2021

While there a growing interest in Voluntary Carbon Disclosure (VCD), comparatively little is discussed whether the improved quality of voluntary carbon disclosure can lead to subsequent changes in a company's carbon reduction performance. Drawing on companies under the Korean Emission Trading Scheme (ETS) with the contents analysis of their sustainable reports, the present research seeks to address the existing knowledge gaps in the current literature on environmental disclosure. Findings empirically show that an increase in the voluntary carbon disclosure score is positively transformed into changes in carbon performance and further develop that the effect of voluntary carbon disclosure on carbon performance varies depending on changes in management capability with the moderation effect.

• New Physics: Sae Mulli
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• v.68 no.11
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• pp.1231-1239
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• 2018

This study aimed at examining undergraduate students' writing about experiments related to the photoelectric effect and giving some implications for experiment education. Thus, this study analyzed 26 students' reports about three kinds of experiments: measuring Planck's constant, comparing the photocurrent and the photovoltage across the intensity of light, and comparing the photocurrent and the photovoltage across the frequency of light. In the measurements, less than 25% of the students expressed the data to the correct number of significant figures even though two-thirds of the students successfully obtained the data given in the manual. In terms of interpretation, the students were not aware of the physical meanings of the detailed parts in the graphs. Even though over 50% of the students drew a line relating photocurrent to voltage, no students compared the theoretical to the empirical data or made a judgment as to whether of not the background theory really fit the experiment. The research findings showed that insufficient knowledge and skills for physics inquiry may be an obstacle in performing the experiments well.