• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.688-688
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• 2013

Al-doped ZnO (AZO) thin films have attracted a lot of attention as a cheap transparent conducting oxide (TCO) material that can replace the expensive Sn-doped In2O3. In particular, AZO thin films are widely used as a window layer of chalcogenide-based thin film solar cells such as Cu(In,Ga)Se2 and Cu2ZnSnS4 (CZTS). Mostly important requirements for the window layer material of the thin film solar cells are the high transparency and the low sheet resistance, because they influence the light absorption by the activelayer and the electron collection from the active layer, respectively. In this study, we prepared the AZO thin films by RF magnetron sputtering using a ZnO/Al2O3 (98：2wt%) ceramic target, and the effect of the sputtering condition such as the working pressure, RF power, and the working distance on the optical, electrical, and crystallographic properties of the AZO thin films was investigated. The AZO thin films with optimized properties were used as a window layer of CZTS thin film solar cells. The CZTS active layers were prepared by the electrochemical deposition and the subsequent sulfurization process, which is also one of the cost-effective synthetic approaches. In addition, the solar cell properties of the CZTS thin film solar cells, such as the photocurrent density-voltage (J-V) characteristics and the external quantum efficiency (EQE) were investigated.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.48 no.5
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• pp.768-775
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• 2015

Seasonal variability in the marine seaweed community structure was examined in the intertidal zones at nine study sites in Hallyeohaesang National Park, on the southern coast of Korea from March to October 2014. A total of 145 seaweeds were indentified, comprising 15 green, 41 brown and 89 red algae. Coarsely branched seaweeds were the dominant functional group, comprising 58.95% in species number, whereas filamentous, sheet, thick leathery, crustose and jointed calcareous forms comprised 2.63-17.72% each. The seaweed biomass averaged 358.00 g dry wt/m² and it was maximal at Somaemuldo (847.64 g dry wt/m²) and minimal at Gamam (56.51 g dry wt/m²). Based on biomass, the dominant and subdominant seaweeds were Ulva australis at Gamam, Sargassum thunbergii at Sangju, Ulva australis and S.fulvellum at Neukdo, S.horneri at Dala-Bijindo-Somaemuldo, S. thunbergii at Dapo, and Corallina pilulifera at Songdo. Community indices were as follows: dominance index (DI), 0.43-0.71; richness index (R), 8.26-16.50; evenness index (J'), 0.36-0.54; and diversity index (H'), 1.57-2.19. In conclusion, we found that both biomass and the community structure of seaweeds in Hallyeohaesang National Park were similar to those in other studies of the Southern Sea along the Korean peninsula, and that Hallyeohaesang National Park is a relatively favorable habitat for seaweeds. Future studies should examine the changes in seaweed composition and biomass as they relate to climate change and environmental pollution.

• Journal of Fisheries and Marine Sciences Education
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• v.27 no.1
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• pp.273-283
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• 2015

This study was carried out to examine the species composition and community structure of benthic marine algae at the subtidal zones of Daepo, Wolpyeong, Wimi and Jigwido in south Jeju, Korea from March to December 2009. Total 87 species including 14 green algae, 23 brown algae, and 50 red algae were collected and identified. Among these species, 9 species were found throughout the year. The dominant species which contributed significantly to the total biomass were Ecklonia cava, Undaria pinnatifida, Peyssonnelia capensis, Cladophora wrightiana, Sargassum serratifolium, Grateloupia angusta, Codium coactum, Plocamium cartilagineum, and Sargassum macrocarpum. The average seaweed biomass was 7,578.2 g wet weight $m^{-2}$ and maximum biomass was recorded seasonally in spring ($9,627.6g\;m^{-2}$), while minimum was recorded in autumn ($5,963.0g\;m^{-2}$), by sites maximum biomass Jigwido ($12,889.9g\;m^{-2}$), while minimum was recorded in Daepo ($5,403.8g\;m^{-2}$). The seasonal and regional flora were investigated as six functional groups. A coarsely branched form was the most dominant functional group constituting from 42.9~52.8% of the total flora. Ecological state group (ESG) II, as an opportunistic species, including sheet form, filamentous form, and coarsely branched form, consisted of 31~59 species, constituting 77.5~84.9%.

• Journal of the Korean Ceramic Society
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• v.41 no.4
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• pp.313-322
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• 2004

Thick film photolithography is a new technology in that the lithography process such as exposure and development is applied to the conventional thick film process including screen-printing. In this research, low-temperature cofireable silver paste, which enabled the formation of thick film fine-line using photolithographic technology, was developed. The optimum composition for fine-line forming was studied by adjusting the amounts of silver powder, polymer and monomer, and the additional amount of photoinitiator, and then the effect of processing parameter such as exposing dose on the formation of fine-line was also tested. As the result, it was found that the ratio of polymer to monomer, silver powder loading, and the amount of photoinitiator were the main factors affecting the resolution of fine-line. The developed photosensitive silver paste was printed on low-temperature cofireable green sheet, then dried, exposed, developed in aqueous process, laminated, and fired. Results showed that the thick film fine-line under 20$\mu\textrm{m}$ width could be obtained after cofiring.

• Composites Research
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• v.27 no.3
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• pp.103-108
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• 2014

Fiber reinforced polymer plastic (FRP) structural members are recently available in construction industries due to various material properties such as high specific strength and stiffness, light-weight, and corrosionresistance. The floating PV generation structure can also be an illustration for applying FRP in construction applications. The floating PV generation structure has been recently issued as a representative item for the low carbon and green growth campaign and many related studies have been conducted for the structural safety and commercial viability. Moreover, the floating PV generation structures for the commercial purpose have been constructed. In this paper, the investigation and development processes of elements for the floating PV generation structure are presented during commercialization.

• Fisheries and Aquatic Sciences
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• v.14 no.4
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• pp.389-397
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• 2011

The benthic algal community structures of the seaweed biomass, vertical distribution of dominant seaweeds, and species composition were examined on the rocky shores of Ongdo, Jusamdo, and Woejodo Islands, Korea, in August 2006. A total of 68 seaweeds were identified, comprising 5 green, 11 brown, and 52 red algae from the three study sites. The number of species at Ongdo (32 species) was less than that at Jusamdo (45 species) and Woejodo (44 species). Jusamdo exhibited the maximum seaweed biomass (73.99 g dry $wt/m^2$), while the minimum value was found at Woejodo (36.90 g dry $wt/m^2$). On the three islands, coarsely branched forms were the most dominant functional group in terms of species number and biomass among benthic algal species. The dominant species were Gelidium amansii, Chondrus ocellatus, and Chrysymenia wrightii at Ongdo, Sargasum thunbergii, Ulva pertusa, and Sargassum fusiformis at Jusamdo, and U. pertusa, Undaria pinnatifida, and Corallina pilulifera at Woejodo. Perennial seaweeds were abundant at Ongdo (G. amansii and C. ocellatus) and Jusamdo (S. thunbergii and S. fusiformis), whereas the sheet form of U. pertusa was relatively abundant at Woejodo Island.

• Applied Chemistry for Engineering
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• v.28 no.1
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• pp.35-41
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• 2017

Materials exposed to outside will deteriorate due to various weathering factors such as sunlight, heat, temperature, humidity and so on. Therefore, predicting speed of degradation and life time is a very important issue. This research uses retro-reflective sheets with white and green which are most commonly used colors to conduct the outdoor exposure test and acceleration test of xenon arc in Arizona state in the United States, Chennai in India, Sanary in France and Seosan in Korea to measure the reflective performance of retro-reflection. The accelerated factor was obtained by using regression analysis through reflective values obtained from the acceleration test of xenon arc from Seosan area. Also, by using solar uv program, the accelerated factor of various climate regions were obtained and it was confirmed that the accelerated factor of Senary was 1.04, Arizona 1.82, Chennai 1.92 times higher than that of Seosan.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.46 no.3
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• pp.303-309
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• 2013

Marine algal flora and community structure were investigated seasonally at three sites in Gijang on the south-east coast of Korea from February 2006 to January 2007. A Total of 74 species were collected and identified, including 8 green algae, 16 brown algae, and 50 red algae. Of these, 15 species were found throughout the survey period. Mean biomass was 823.2-1,615.4 g wet weight $m^{-2}$ in winter, 689.1-3,196.8 g wet weight $m^{-2}$ in spring, 574.5-1,219.9 g wet weight $m^{-2}$ in summer, and 747.6-1,616.2 g wet weight $m^{-2}$ in autumn. The flora could be classified into six functional groups: coarsely branched form (37.8%), thick leather form (18.9%), sheet form (13.5%), filamentous form (12.2%), jointed calcareous form (10.8%) and crustose form (6.8%). The R/P, C/P and (R+C)/P values reflecting the flora characteristics were 3.13, 0.50 and 3.63, respectively. The number of marine algae species and the biomass in Gijang area were markedly reduced when compared with previous studies. This result suggests possible future changes in the algal vegetation, considering the physical and chemical pollution loadings in the coastal marine environment of this area.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.40 no.4
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• pp.210-219
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• 2007

The benthic marine algal flora and community structure were examined at five sites of the Taean Peninsula, Korea, during July-August 2005. Ninety-six algal species were Identified, including 14 green, 21 brown, and 60 red algae, and 1 marine plant. The common species that occurred at the five sites were Sargassum thunbergii, Gelidium divaricatum, Caulacanthus okamurae, Gracilavia vermiculophylla, and Neorhodomela aculeata. Sthunbergii was the dominant species in terms of coverage and biomass at ail of the study sites. The average biomass varied from $23.72g/m^2$ in dry weight at Chaeseokpo to $66.43g/m^2$ at Padori. The species could be divided into six functional groups in terms of morphological characteristics: 41 coarsely branched forms, 25 filamentous forms, 16 sheet forms, 7 thick leathery forms, including the marine plant Phyllospadix iwatensis, 4 crustose forms, and 3 Jointed calcareous forms. The seaweed communities at the five study sites were unstable and the environmental conditions were bad or very bad. Among the five study sites, the ecological evaluation index (EEI) and diversity index (H') were maximal at Padori at 2.29 and 1.98, respectively. By contrast, the dominance index (DI) was minimal at Padori (0.55) and maximal at Baramarae (0.96). Therefore, we conclude that the rocky shore at Padori has the best environment among the five study sites, although the species richness and biomass of seaweeds have declined continuously over the last 10 years.

• Journal of the Korea institute for structural maintenance and inspection
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• v.20 no.1
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• pp.112-117
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• 2016

For artificial ground greening construction without root-proofing layer, this research reviewed the effect on watertightness of asphalt waterproofing layer by plant roots penetration based on crack width, and crack penetrated roots. Experiment on concrete crack width was performed with three conditions such as 0.15, 0.30, and 0.45 mm, and all three conditions confirmed that all plant roots penetrations were made through crack area in 12 ~ 18 months. In addition, according to evaluation of effects on waterproofing layer by crack penetrated plant roots and in condition of 0.45 mm crack width, it indicated that penetration is made on asphalt waterproofing layer in 12 months due to roots penetration.