• Proceedings of the Korean Vacuum Society Conference
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• 2009.08a
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• pp.192-192
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• 2009

• 한국신재생에너지학회:학술대회논문집
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• 2009.11a
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• pp.399-399
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• 2009

CIS계 화합물 태양전지는 높은 광흡수계수와 열적 안정성 및 Ga 조성 조절을 통한 밴드갭 조절이 용이해 고효율 박막 태양전지로 각광 받고 있다. CIS 태양전지의 광 흡수층 제조 방법으로는 여러 가지 방법이 있지만 본 연구에서는 가장 높은 에너지 변환 효율을 달성한 Co-Evaporation 방법을 사용하기로 하였다. 미국의 NREL의 경우 Co-Evaporation 방법을 사용해 20%의 에너지 변환 효율을 달성한 바가 있다. 하지만 이러한 효율의 태양전지는 실험실에서 연구용으로 제작한 아주 작은 면적으로 태양전지 양산화에 그대로 적용하기는 힘들다. 따라서 CIGS 태양전지의 양산화 적용을 위해 대면적화가 필수적이다. 본 연구에서는 기존의 3 stage 방식을 이용해 광흡수층을 증착하여 최적화 조건을 연구하였다. 또한 기판의 면적 증가에 따라 효율과 Voc, Jsc, F.F가 얼마나 감소하는지 실험하여 보았다. 기판은 soda lime glass를 사용 하였으며 후면 전극으로 약$1{\mu}m$ 두께의 Mo를 DC Supptering 방법을 이용해 증착하였다. 다음으로 약 $2{\mu}m$이상의 광흡수층을 Co-Evaporation 방법을 이용하여 증착 하였으며 buffer층으로는 약 50nm의 CdS층을 CBD방법을 이용하여 제조 하였다. TCO층으로 약 50nm의 i-ZnO와 약 450nm의 Al-ZnO를 RF Sputtering 방법을 이용하여 증착 하였다. 마지막으로 앞면 전극으로 약 $3{\mu}m$의 Al을 Thermal Evaporation 방법으로 증착하였다. 태양전지 소자의 면적은 $0.49cm^2$, $25cm^2$, $100cm^2$로 각각 면적을 달리하며 효율을 비교 분석하였다.

• KSBB Journal
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• v.17 no.6
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• pp.571-576
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• 2002

Recombinant E. coli DH5 ${\alpha}$/pSB311 was made by cloning the genes encoding bacterial luciferase and aldehyde substrate proteins from Photohabdus luminescense, to complement defects of Lumistox, which is normally used in bioassays to monitor toxic substances in water environmental systems. The conditions for stable light production by the recombinant strains were investigated with respect to cell growth stage, cell number, and buffer conditions. The optimum growth stage was a middle-exponential stage with an OD$_{660nm}$ value of 0.6-0.7. ADout 10$^{6}$-10$^{7}$ cells per test tube was optimum for stable light emission. The effect of buffer was not significant if an optimum viable cell number was maintained. The bioluminescence of the recombinant E. coli harboring the lux operon of Photohabdus luminescense was not affected by temperature, while the bioluminescence of Lumistox was temperature sensitive. The recombinant E. coli was more sensitive to heavy metals (Cd, Cu, Hg, Zn) than Lumistox, because it does not require high concentrations of NaCl in the buffer.

• Journal of the Korean Chemical Society
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• v.30 no.2
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• pp.216-223
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• 1986

Separation of optical isomers of DNS derivatized amino acids by a reversed-phase high-performance liquid chromatography has been studied by adding a complex of an optically active amino acid (L-arginine) with the metal ion (Cu(II), Zn(II), Cd(II), Ni(II)) to the mobile phase. The separations are affected by the concentrations of acetonitrile, chelate and buffer. They are also affected by the pH and the kinds of metal and buffer. A separation mechanism, which is based on steric effect of the ligand exchange reaction for the formation of ternary complexes by the D,L-DNS-amino acids and the chiral additive associated with the stationary phase, is proposed to interpret the elution behaviors of D, L-dansyl-amino acids.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.464.1-464.1
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• 2014

Among numerous material candidates, Cu(InxGa1-x)(SySe2-y) (CIGS) thin films have emerged as promising material candidates for thin film solar cell applications due to the high energy conversion efficiency and relatively low fabrication cost. The CIGS thin film solar cells consist of several materials, including Mo back contacts, ZnO-based window layers, and CdS buffer layers. All these materials have different crystal structures and contain quite distinct chemical elements, and hence the device characterization requires careful analyses. Most of all, identification of the major trap states resulting in the carrier recombination processes is a key step toward realization of high efficiency CIGS solar cells. We have carried out electrical investigations of CIGS thin film solar cells to specify the major trap states and their roles in photovoltaic performance. In particular, we have used the temperature-dependent transport characterizations and admittance spectroscopy. In this presentation, we will introduce some exemplary studies of DC and AC electrical characteristics of the CIGS solar cells.

• 한국신재생에너지학회:학술대회논문집
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• 2006.06a
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• pp.222-224
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• 2006

A non-vacuum process for $Cu(In,Ga)Se_2$ (CIGS) thin film solar cells from nanoparticle precursors was described in this work CIGS nanoparticle precursors was prepared by a low temperature colloidal route by reacting the starting materials $(CuI,\;InI_3,\;GaI_3\;and\;Na_2Se)$ in organic solvents, by which fine CIGS nanoparticles of about 20nm in diameter were obtained. The nanoparticle precursors were mixed with organic binder material for the rheology of the mixture to be adjusted for the doctor blade method. After depositing the mixture of CIGS with binder on Mo/glass substrate, the samples were preheated on the hot plate in air to evaporate remaining solvents ud to burn the organic binder material. Subsequently, the resultant (porous) CIGS/Mo/glass simple was selenized in a two-zone Rapid Thermal Process (RTP) furnace in order to get a solar ceil applicable dense CIGS absorber layer. Complete solar cell structure was obtained by depositing. The other layers including CdS buffer layer, ZnO window layer and Al electrodes by conventional methods. The resultant solar cell showed a conversion efficiency of 0.5%.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.05c
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• pp.108-111
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• 2002

CIGS film has been fabricated on soda-lime glass, which is coated with Mo film. by multi-source evaporation process. The films has been prepared with thickness of 1.0 ${\mu}m$, 1.75${\mu}m$, 2.0${\mu}m$, 2.3${\mu}m$, and 3.0${\mu}m$. X-ray diffraction analysis with film thickness shows that CIGS films exhibit a strong (112) preferred orientation. Furthermore. CIGS films exhibited distinctly decreasing the full width of half-maximum and (112) preferred peak with film thickness. Also, The film's microstructure, such as the preferred orientation, the full width at half-maximum(FWHM), and the interplanar spacing were examined by X-ray diffraction. The preparation condition and the characteristics of the unit layers were as followings ; Mo back contact DC sputter, CIGS absorber layer : three-stage coevaporation, CdS buffer layer : chemical bath deposition, ZnO window layer : RF sputtering, $MgF_2$ antireflectance : E-gun evaporation

• Journal of the Korean Society of Environmental Restoration Technology
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• v.14 no.3
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• pp.15-32
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• 2011

This study was carried out to investigate the soil characteristics and propose the management for the Monument Beobsoo Marsh, Korea. The soil properties of O.M, $Ca^{2+}$, $Na^+$ and CEC were higher and the soil properties of pH_{1:5}$ and $P_2O_5$ were lower the studied sites than other marsh sites in Korea. Although the Heavy metals such as Pb, Hg, Cd, Cu, Zn, Cr and As were lower compare to the safety standard of soil pollution in Korea, the overall conservation management plan based on long-term monitoring should be considered just because it varied by the point and non-point source pollution within the studied marsh. The source of water pollution varied due to non-point polluting origins such as sewage inlet, degraded terrain for agriculture, fishing sites, sites of removed water grasses, pesticides, chemical fertilizers, as well as fallen leaves. The creation of an artificial marsh is recommended due to the soil environment of the studied sites may be changed owing to the accumulated contaminants from the sources of both of point or non-point contaminants. The establishment of the zones of core, buffer and transition which is basic management structure of the UNESCO MaB could be applied to manage the studied site. Simultaneously the promotion of voluntary participation and education of the local residents are needed.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.268-268
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• 2016

Chemical sensors have attracted much attention due to their various applications such as agriculture product, cosmetic and pharmaceutical components and clinical control. A conventional chemical and biological sensor is consists of fluorescent dye, optical light sources, and photodetector to quantify the extent of concentration. Such complicated system leads to rising cost and slow response time. Until now, the most contemporary thin film transistors (TFTs) are used in the field of flat panel display technology for switching device. Some papers have reported that an interesting alternative to flat panel display technology is chemical sensor technology. Recent advances in chemical detection study for using TFTs, benefits from overwhelming progress made in organic thin film transistors (OTFTs) electronic, have been studied alternative to current optical detection system. However numerous problems still remain especially the long-term stability and lack of reliability. On the other hand, the utilization of metal oxide transistor technology in chemical sensors is substantially promising owing to many advantages such as outstanding electrical performance, flexible device, and transparency. The top-gate structure transistor indicated long-term atmosphere stability and reliability because insulator layer is deposited on the top of semiconductor layer, as an effective mechanical and chemical protection. We report on the fabrication of InGaZnO TFTs with silver nanowire as the top gate electrode for the aim of chemical materials detection by monitoring change of electrical properties. We demonstrated that the improved sensitivity characteristics are related to the employment of a unique combination of nano materials. The silver nanowire top-gate InGaZnO TFTs used in this study features the following advantages: i) high sensitivity, ii) long-term stability in atmosphere and buffer solution iii) no necessary additional electrode and iv) simple fabrication process by spray.

• Analytical Science and Technology
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• v.9 no.4
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• pp.336-344
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• 1996

The extraction of trace cobalt, copper, nickel, cadmium, lead and zinc in urine samples of organic and alkali metal matrix into chloroform by the complex with a dithizone was studied for graphite furnace AAS determination. Various experimental conditions such as the pretreatment of urine, the pH of sample solution, and dithizone concentration in a solvent were optimized for the effective extraction, and some essential conditions were also studied for the back-extraction and digestion as well. All organic materials in 100 mL urine were destructed by the digestion with conc. $HNO_3$ 30 mL and 30% $H_2O_2$ 50 mL. Here, $H_2O_2$ was added dropwise with each 5.0 mL, serially. Analytes were extracted into 15.0 mL chloroform of 0.1% dithizone from the digested urine at pH 8.0 by shaking for 90 minutes. The pH was adjusted with a commercial buffer solution. Among analytes, cadmium, lead and zinc were back-extracted to 10.00 mL of 0.2 M $HNO_3$ from the solvent for the determination, and after the organic solvent was evaporated, others were dissolved with $HNO_3-H_2O_2$ and diluted to 10.00 mL with a deionized water. Synthetic digested urines were used to obtain optimum conditions and to plot calibration-eurves. Average recoveries of 77 to 109% for each element were obtained in sample solutions in which given amounts of analytes were added, and detection limits were Cd 0.09, Pb 0.59, Zn 0.18, Co 0.24, Cu 1.3 and Ni 1.7 ng/mL, respectively. It was concluded that this method could be applied for the determination of heavy elements in urine samples without any interferences of organic materials and major alkaline elements.