• Proceedings of the Korean Society of Computer Information Conference
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• 2013.07a
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• pp.369-371
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• 2013

본 연구에서는 태양광 발전시스템의 각 부분별로 환경적 요소와 상황적 요소로부터 정보 데이터 수집 및 분석, 제어, 평가, 진단, 모니터링 등을 위해 기 활용되고 있는 통신기술 등 IT 융합 기술을 적용하여 이를 DB화하여 표준적인 가이드라인 및 서비스 기준과 상용화가 가능한 비즈니스 모델 개발을 개발하고, 태양광 발전설비 최적 운영관리 서비스 요소 및 시스템 개발을 통해 다양한 인버터 종류의 데이터를 통합할 수 있는 시스템과 태양광 발전설비 최적 운영관리 서비스 프로그램을 구현하였다.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.295-295
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• 2010

Nanoparticles of the compound semiconductor, Cu(In, Ga)Se2 (CIGS), were synthesized in solution under ambient pressure below $100^{\circ}C$ and characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), optical absorption spectroscopy and energy-dispersive X-ray (EDX) analyses. These materials have chalcopyrite crystal structures and the particle sizes less than 100 nm. Synthetic conditions were studied for the crystallized CIGS nanoparticles formation to prevent from side products of Cu2Se, Cu2-xSe, and CuSe etc. The single phase CIGS nanoparticles were applied to coating of thin films photovoltaic cells. The electro deposition of CIGS thin films is also a good non-vacuum technology and under investigation. In aqueous solutions, the different chemical compositions of CIGS thin films were obtained, depending on pH, concentration of starting materials and deposition potentials. The surface morphology of the prepared CIGS thin films depends on the complexing ligands to the solutions during the electrochemical deposition.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.68-73
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• 1998

This paper presents a novel prototype of active voltage clamped quasi-resonant ZVS-PWM forward DC-DC converter designed for specific low voltage high current application. We establish the soft-switching forward converter with a high frequency isolated link which can efficient operate over wide load ranges under conditions of zero voltage soft-switching and active voltage clamped switching. In addition, we evaluate connection of the soft-switching forward converter with large capacitor which capacitance is over 100[F].

• Journal of Power Electronics
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• v.18 no.3
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• pp.826-840
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• 2018

This paper presents a distributed maximum power point tracking (DMPPT) algorithm based on the reference voltage perturbation (RVP) method for the PV modules of a series PV string. The proposed RVP-DMPPT algorithm is developed to accurately track the maximum power point (MPP) for each PV module operating under all atmospheric conditions with a reduced hardware overhead. To study the influence of parameters such as the controller reference voltage ($V_{ref}$) and PV current ($I_{pv}$) on the PV string voltage, a small signal model of a unidirectional differential power processing (DPP) based PV-Bus architecture is developed. The steady state and dynamic performances of the proposed RVP DMPPT algorithm and small signal model of the unidirectional DPP based PV-Bus architecture are demonstrated with simulations and experimental results. The accuracy of the RVP DMPPT algorithm is demonstrated by obtaining a tracking efficiency of 99.4% from the experiment.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.28-28
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• 2010

Photoelectrochemical solar cells such as dye-sensitized cells (DSSCs), which exhibit high performance and are cost-effective, provide an alternative to conventional p-n junction photovoltaic devices. However, the efficiency of such cells plateaus at 11-12%, in contrast to their theoretical value of 33%. Improvements in efficiency can only occur through a fundamental understanding of the underlying physics, materials, and device designs of DSSCs. A photoelectrode consisting of semiconducting oxide nanoparticles and a transparent conducting oxide electrode (TCO) is a key component of DSSC and design of photoelectrode materials is one of promising strategies to improving energy conversion efficiency. We introduce monodisperesed $TiO_2$ nanoparticles prepared by forced hydrolysis method and their superiority as photoelectrode materials was characterized with aids of optical and electrochemical analysis. Multi-layered TCO materials are also introduced and their feasibility for use as photoelectrodes is discussed in terms of optical absorption and charge collecting properties.

• Bulletin of the Korean Chemical Society
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• v.21 no.10
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• pp.1047-1048
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• 2000

Dye-sensitized nanocrystalline rutile $TiO_2$ solar cells were prepared, and the influence of Li+ and 1,2-dimethyl-3-hexyl imidazolium ions in the electrolyte on the photovoltaic properties was compared. The electrolyte con-taining Li+ ions produced a lower open-circuit photovoltage than the electrolyte with 1,2-dimethyl-3-hexyl im-idazolium ions, suggesting that the adsorption of Li+ ions to the rutile $TiO_2$ surface causes a shift in the band edges toward more positive potentials. At the same time, both the short-circuit photocurrent and the maximum value of the incident-photon-current conversion efficiency (IPCE) of the electrolyte containing Li+ ions were relatively higher. Data analysis suggests that presence of adsorbed Li+ ions improves via the phenomenon of band-edge movement the charge-injection efficiency by altering both the energy and number of excited state levels of the dye that participate in electron injection.

• International Journal of Computer Science & Network Security
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• v.22 no.5
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• pp.17-24
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• 2022

Hierarchical clustering methods have been proposed for more than sixty years and yet are used in various disciplines for relation observation and clustering purposes. In 1965, divisive hierarchical methods were proposed in biological sciences and have been used in various disciplines such as, and anthropology, ecology. Furthermore, recently hierarchical methods are being deployed in economy and energy studies. Unlike most clustering algorithms that require the number of clusters to be specified by the user, hierarchical clustering is well suited for situations where the number of clusters is unknown. This paper presents an overview of the hierarchical clustering algorithm. The dissimilarity measurements that can be utilized in hierarchical clustering algorithms are discussed. Further, the paper highlights the various and recent disciplines where the hierarchical clustering algorithms are employed.

• Resources Recycling
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• v.30 no.2
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• pp.39-45
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• 2021

Spent photovoltaic module is one of the important resource of silver, while related research concerning silver recovery remains limited. In our previous research, HNO3 was utilized to dissolve Ag(I) and Al(III) from the spent silicon solar cells. In order to recover Ag(I) from the leachate of a silicon solar cell, the present study made use of a nitrate solution containing Ag(I) and Al(III), which was subjected to a solvent extraction process with 5,8-diethyl-7-hydroxydodecan-6-oxime (LIX63). Ag(I) was selectively extracted with LIX63 over Al(III) from the nitrate leach solution. Subsequently, quantitative stripping of Ag(I) from the loaded LIX63 was performed by using 20% ammonia water. The McCabe-Thiele plots for the extraction and stripping isotherms of Ag(I) were also constructed. Extraction and stripping simulation tests confirmed an Ag(I) extraction and stripping efficiency of >99.99% and 98.9%, respectively with high purity Ag (99.998%) and Al (99.99%) solution. A process flow sheet for Ag(I) recovery from the nitrate leach solution was proposed.

• Journal of Bio-Environment Control
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• v.18 no.3
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• pp.177-184
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• 2009

For the purpose of reducing the cost for greenhouse operation by acquiring the electric power necessary for it, this study installed a solar photovoltaic system on the roof of the building adjacent to green-houses and experimentally examined the quantity of power generation based on weather conditions. The results of the study are as per the below: The maximum, average and minimum temperature while the experiment was conducted was $0.4{\sim}34.1,\;-6.1{\sim}22.2$, and $-14.1{\sim}16.7^{\circ}C$ respectively, and the solar radiation was $28.8MJ{\cdot}m^{-2}$ (maximum), $14.9MJ{\cdot}m^{-2}$ (average), and $0.6MJ{\cdot}m^{-2}$ (minimum). The quantity of electric power didn't increase in proportion to the quantity of solar radiation and instead, it was almost consistent around 750W. Daily maximum, average and minimum consumption of electric power was 5.2kWh, 2.5kWh and 0kWh respectively. Based on the average electric power consumption of the system used for this experiment, it was sufficient in case the capacity and the working time of a hot blast heater are small, but it was short in case they are big. In case the capacity of the hot blast heater is big, the average electric power quantity will be sufficient for array area $21m^2$, about three times of the present area. In summer when the temperature of the array becomes high, the generation of electric power didn't increase in proportion to the quantity of solar radiation, but this experiment result shows a high correlation between two factors (coefficient of correlation 0.84).

• Journal of Korea Foundry Society
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• v.33 no.2
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• pp.69-74
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• 2013

Silicon (Si) wafer was grown by using direct growth from Si melt and contaminations of wafer during the process were investigated. In our process, BN was coated inside of all graphite parts including crucible in system to prevent carbon contamination. In addition, coated BN layer enhance the wettability, which ensures the favorable shape of grown wafer by proper flow of Si melt in casting mold. As a result, polycrystalline silicon wafer with dimension of $156{\times}156$ mm and thickness of $300{\pm}20$ um was successively obtained. There were, however, severe contaminations such as BN and SiC on surface of the as-grown wafer. While BN powders were easily removed by brushing surface, SiC could not be eliminated. As a result of BN analysis, C source for SiC was from binder contained in BN slurry. Therefore, to eliminate those C sources, additional flushing process was carried out before Si was melted. By adding 3-times flushing processes, SiC was not detected on the surface of as-grown Si wafer. Polycrystalline Si wafer directly grown from Si melt in this study can be applied for the cost-effective Si solar cells.