• Current Photovoltaic Research
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• v.11 no.3
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• pp.67-74
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• 2023

The earth-abundant element-based Cu₂ZnSn(S,Se)₄ (CZTSSe) thin film solar cells (TFSCs) have attracted greater attention in the photovoltaic (PV) community due to their rapid development in device power conversion efficiency (PCE) >13%. In the present work, we demonstrated the fine-tuning of the bandgap in the CZTSSe TFSCs by altering the sulfur (S) to the selenium (Se) chalcogenide ratio. To achieve this, the CZTSSe absorber layers are fabricated with different S/(S+Se) ratios from 0.02 to 0.08 of their weight percentage. Further compositional, morphological, and optoelectronic properties are studied using various characterization techniques. It is observed that the change in the S/(S+Se) ratios has minimal impact on the overall Cu/(Zn+Sn) composition ratio. In contrast, the S and Se content within the CZTSSe absorber layer gets altered with a change in the S/(S+Se) ratio. It also influences the overall absorber quality and gets worse at higher S/(S+Se). Furthermore, the device performance evaluated for similar CZTSSe TFSCs showed a linear increase and decrease in the open circuit voltage (V_oc) and short circuit current density (J_sc) of the device with an increasing S/(S+Se) ratio. The external quantum efficiency (EQE) measured also exhibited a linear blue shift in absorption edge, increasing the bandgap from 1.056 eV to 1.228 eV, respectively.

• KIEAE Journal
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• v.15 no.1
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• pp.21-27
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• 2015

In the case of public buildings, fast communication and transparency in the administration and the public, as well as ensuring visibility and lighting performance using a glass curtain wall is symbolically expressed through the transparent glass skin. This study is a simulation in order to derive the basic data for the establishment of the improvement of the heating and cooling load analysis according to the window area ratio changes with respect to the high effectiveness of the government's large public building energy consumption analysis and green building certification system of guidelines was analyzed by a change in the energy load. Glass curtain wall is light and visibility, the symbolic meaning of communication, etc., but is widely used in a variety of characteristics, in terms of energy consumption being disadvantaged sheath plan should have been. Design, including the Atrium, is much less energy than energy consumption by the window area ratio. Thus, while compliance with design guide lines, the atrium and I like the burden of a large space ratio and energy load consists of only glass suggest that require more research on that given in the guidelines.

• Transactions of the Korean hydrogen and new energy society
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• v.12 no.4
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• pp.287-292
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• 2001

The optical transmittance change of Pd thin film due to hydrogen absorption and desorption was examined at room temperature. Hydrogen absorption and desorption cycling effects on optical transmittance were measured 6 times in the pressure range between 0 and 640 torr. Optical transmittance of Pd film was increasing with increasing hydrogen pressure. Ratio of optical transmittance to the change of pressure at $\beta$ phase is bigger than that of low hydrogen pressure range.

• Transactions of the Korean hydrogen and new energy society
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• v.12 no.3
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• pp.201-209
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• 2001

The change of optical transmittance of $PdH_x$ thin film due to hydrogen concentration change was measured at room temperature. Pd film($312{\AA}$ thick) was made by thermal evaporation on glass substrate. Hydrogen absorption and desorption cycling effect on optical transmittance was measured 4 times in the pressure range between 0 and 640 torr. Ratio of optical transmittance to the change of ln pressure(torr) increases with increasing number of hydrogen A-D cyclings in the ${\beta}$ phase.

• Environmental and Resource Economics Review
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• v.24 no.2
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• pp.411-433
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• 2015

This paper decomposed energy productivity changes across 14 Korean manufacturing industries into 5 components, technological catch-up(EC), technological progress(TC), and changes in labor-energy ratio(LC), capital-energy ratio(KC) and energy mix(EMC). Then we also figured out the possible relationship between energy productivity change and export growth rate across the industries. It is found that (1) technological progress, changes in capital-energy ratio and energy mix contribute to energy productivity growth in Korea during the sample period, (2) technological progress is the primary driving forces for energy productivity growth, (3) increase in export growth rate had a positive impact on energy productivity growth excepting a part of energy-intensive industries.

• Journal of the Korean Society of Combustion
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• v.12 no.1
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• pp.1-10
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• 2007

Analytical investigation of acoustic wave scattering from turbulent premixed flames was conducted to evaluate the acoustic energy amplification/damping. Such acoustic energy change is attributed to the acoustic velocity jump due to flame's heat release. Small perturbation method up to second order and stochastic analysis were utilized to formulate net acoustic energy and the energy transfer from coherent to incoherent energy. Randomly wrinkled flame surface is responsible for the energy transfer from coherent to incoherent field. Nondimensional parameters that govern net acoustic energy were determined: rms height and correlation length of flame front, incident wave frequency, incidence angle, and temperature ratio. The dependence of net acoustic energy upon these parameters is illustrated by numerical simulations in case of Gaussian statistics of flame front. Total net energy was amplified and the major factors that affect such energy amplification are incidence angle and temperature ratio. Coherent (incoherent) energy is damped (amplified) with rms height and correlation length of flame front.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.2
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• pp.189-199
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• 2000

This paper investigates the thermodynamic performance of latent heat thermal energy storage system using two phase change materials(2-PCM system). The thermodynamic merit of using 2-PCM is clear in terms of exergetic efficiency, which is substantially higher than that of 1-PCM system. Optimum phase change temperature to maximize the exergetic efficiency exists for each case. The heat transfer area ratio of high temperature storage unit, X, becomes another important parameter for 2-PCM system if the phase change temperatures of given materials are different from those of optimum conditions. It is a good approximation for X$_{opt}$ to be 0.5 when optimum phase change temperatures are used. Otherwise X$_{opt}$ is determined differently as a function of given phase change temperatures.res.

• Journal of Power System Engineering
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• v.17 no.3
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• pp.57-64
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• 2013

This study focus on the analysis of the energy performance in accordance with apartment houses arrangement type by using Ecotect Analysis. Korea, energy-poor country, the rate of dependence on imports amount to 94%, have to reduce energy consumption part of building except in industry and transport which affect the economic. Apartment houses are built in various forms in order to reduce energy, are modelled in each window area ratio, shape, orientation, climate through simulation. Through this study, we can analyze energy performance by form, window area ratio, orientation, climate change and know the optimal elements by the form. In particular, although there have been studied research on the window area ratio and research related to the arrangement form, determined that the information on the regional climate characteristics and the direction of placement is less than existing research. To supplement those problem, adding to seven direction(West, S-60-W, S-30-W, South, S-30-E, S-60-E, East) and climatic element(southern region) is characteristic of this study. The form of apartment houses was modelled for apartment houses built in the 10 years since. And each modeling were analyzed by Ecotect Analysis.

• Journal of Korean Association for Spatial Structures
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• v.2 no.1 s.3
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• pp.41-49
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• 2002

In this paper, a study of 2-step damage detection for space truss structures using the extended Kalman filter theory is presented. Space truss structures are composed of many members, so it is difficult to find damaged member from the whole system. Therefore, 2-step damage identification method is applied to detect the damaged members. First, kinetic energy change ratio is used to find damage region including damaged member and then detect damaged member using extended Kalman filtering algorithm in damage region. The effectiveness of proposed method is verified through the numerical examples.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.7
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• pp.1339-1346
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• 2011

This paper is developed to demand management scenario of energy consumption efficiency improvement, electricity generation efficiency improvement, network efficiency improvement, change of distribution ratio, movement of energy source, change of heating system, put of CHP to quantitatively assess to impact on energy use of demand management at the national level. This scenario can be applied Energy System Management model was developed based on Energy Balance Flow. In addition, effect analysis through built demand management scenario was quantitatively evaluated integrated demand management effectiveness of energy cost saving, CO2 emission reduction and energy savings of national level by calculating to primary energy source usage change in terms of integration demand management effect more often than not a single energy source separated electricity, heat and gas.