• Current Photovoltaic Research
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• 제11권3호
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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.

• 웰빙융합연구
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• 제7권3호
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• pp.1-11
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• 2024

Purpose: The purpose of this study is to present an efficient emission reduction ratio of plastic to reduce carbon dioxide, the main cause of greenhouse gases. Research design, data and methodology: This study calculated the absolute value of carbon dioxide by setting an equation through the emission coefficient using the US EPA's WARM model. Results: In the recycling ratio of 70%, it was found that the energy recovery ratio was 15.6%, which was the energy recovery ratio without generating carbon dioxide. When carbon dioxide is generated by changing plastic waste emissions, optimal efficiency is achieved by reducing emissions by 10% to 30% of energy recovery ratio, 20% to 50% of energy recovery ratio, and 30% to 80% or more of energy recovery ratio. Conclusions: The recycling rate should be set at a minimum of 70%, so that a carbon dioxide-free energy recovery rate could be obtained during the recycling process, supporting an eco-friendly basis for environmental policies aimed at this rate. In addition, it was possible to suggest that it is essential to reduce emissions by at least 30% for eco-friendly recycling measures that can achieve both economic and environmental feasibility in the energy recovery process through incineration during recycling in Korea.

• KIEAE Journal
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• 제15권1호
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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.

• 한국수소및신에너지학회논문집
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• 제12권4호
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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.

• 한국수소및신에너지학회논문집
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• 제12권3호
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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.

• 자원ㆍ환경경제연구
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• 제24권2호
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• pp.411-433
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• 2015

본 연구는 거리함수에 기초한 분해분석을 활용하여 표본기간 1995년부터 2009년 한국 14개 제조업의 에너지 생산성 변화요인을 분석한다. 산출거리함수를 적용한 분해산식은 기술적 성장에 따른 생산성 성장효과를 생산요소 및 에너지 믹스와 관련된 다양한 분해요인으로 세분화하는 장점이 있으며 추정결과를 요약하면 다음과 같다. 첫째 한국 제조업은 90년대 후반 이후 전반적인 에너지 생산성의 향상을 보였으며 표본기간 에너지 저소비형 산업이 경험한 경제적 성과가 핵심적인 요인으로 작용하였다. 둘째 생산프론티어의 성장을 의미하는 기술적 진보에 의한 에너지 생산성 성장이 크게 표출되었으며 효율성 개선을 통한 성장여지가 존재한다. 셋째 주요 생산요소인 노동 및 자본과 관련된 분해요인은 에너지 생산성 변화에 상호 상충된 영향을 미쳤으며 에너지 믹스에 의한 생산성 성장이 확인되었다. 다음으로 본 연구는 산업별 에너지 생산성 변화와 수출성장률의 관계를 추가적으로 분석하였으며 일부 에너지 집약 산업을 제외한 대부분의 산업부문에서 수출생산 성장률과 에너지 생산성의 성장 간 양(+)의 상관관계를 확인하였다.

• 한국연소학회지
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• 제12권1호
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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.

• 설비공학논문집
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• 제12권2호
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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.

• 동력기계공학회지
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• 제17권3호
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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.

• 한국공간구조학회논문집
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• 제2권1호
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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.