• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.413-413
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• 2012

Lead sulfide (PbS) Colloidal quantum dots (CQDs) are promising material for the photovoltaic device due to its various outstanding properties such as tunable band-gap, solution processability, and infrared absorption. More importantly, PbS CQDs have large exciton Bohr radius of 20 nm due to the uniquely large dielectric constants that result in the strong quantum confinement. To exploit desirable properties in photovoltaic device, it is essential to fabricate a device exhibiting stable performance. Unfortunately, the performance of PbS NQDs based Schottky solar cell is considerably degraded according to the exposure in the air. The air-exposed degradation originates on the oxidation of interface between PbS NQDS layer and metal electrode. Therefore, it is necessary to enhance the stability of Schottky junction device by inserting a passivation layer. We investigate the effect of insertion of passivation layer on the performance of Schottky junction solar cells using PbS NQDs with band-gap of 1.3 eV. Schottky solar cell is the simple photovoltaic device with junction between semiconducting layer and metal electrode which a significant built-in-potential is established due to the workfunction difference between two materials. Although the device without passivation layer significantly degraded in several hours, considerable enhancement of stability can be obtained by inserting the very thin LiF layer (<1 nm) as a passivation layer. In this study, LiF layer is inserted between PbS NQDs layer and metal as an interface passivation layer. From the results, we can conclude that employment of very thin LiF layer is effective to enhance the stability of Schottky junction solar cells. We believe that this passivation layer is applicable not only to the PbS NQDs based solar cell, but also the various NQDs materials in order to enhance the stability of the device.

• The Korea Journal of Herbology
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• v.34 no.1
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• pp.99-107
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• 2019

Objectives : Cudrania tricuspidata (C. tricuspidata) is well-known traditional herbal remedy and its root, leaf and fruit were used for treatment of inflammation, tumor and painkilling. However, effect of C. tricuspidata fruit on tight junction is still unknown. The aim of this research was to determine the effect of C. tricuspidata fruit extract on human keratinocyte HaCaT cells. Methods : The antioxidant effects of water extract of C. tricuspidata (WECT) and ethanol extract of C. tricuspidata (EECT) were analyzed by using an ABTS assay. To confirm the cytotoxicity of WECT and EECT, MTS assay was performed. The mRNA expression levels of tight junction related genes were analyzed using quantitative RT-PCR analysis. Furthermore, dispase assay was used to investigate the alteration of cell-cell adhesion strength of EECT treated HaCaT cells. Results : WECT and EECT showed strong antioxidant activity. No obvious cytotoxicity was observed in both WECT and EECT until $2.0mg/m{\ell}$ concentration. The mRNA expression level of Claudin 6 were significantly increased by EECT treatment, whereas the WECT did not affect the expression of Claudin 6. Furthermore, EECT treatment enhances cell-cell adhesion strength. Conclusions : In this study, we investigated the physiological activities of the extracts of Cudrania tricuspidata fruit extracts on human keratinocytes by two different extraction methods. EECT might have an anti-aging activity on the skin by reducing oxidative stress. Moreover, it may be a useful ingredient in atopic dermatitis and skin-moisturizing, given its effects of altering Claudin 6 gene expression and enhancing cell-cell adhesion strength.

• The Korea Journal of Herbology
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• v.36 no.5
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• pp.59-67
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• 2021

Objectives : Hibiscus (Hibiscus sabdariffa L.) is rich in antioxidants such as flavonoids and anthocyanins and is known to have anti-inflammatory activity and anti-aging function of the skin, but there is no study on its effect on the skin barrier. This study aim to investigate the positive effect on the skin barrier by confirming the effect of water extracts of Hibiscus sabdariffa L. (WEHS) on the tight junction-related gene expression. Methods : The antioxidant efficacy of WEHS was investigated through ABTS and DPPH assays, and 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium was performed to examine the effect on cell viability. quantitative Reverse transcription polymerase chain reaction and immunoblot analysis were performed to confirm the effect of WEHS on the expression of tight junction-related genes, and immunofluorescence microscopy was used to confirm the movement of Claudin 1 protein into tight junctions. Results : WEHS showed strong antioxidant activity and induced an increase in both mRNA and protein expression levels of Claudin 1 among tight junction-related genes. The strong localization of Claudine 1 protein increased by WEHS to the tight junction was confirmed by immunofluorescence microscopy. Conclusions : Hibiscus was confirmed through this study to show antioxidant activity and the function of promoting the expression of the tight junction Claudin 1 gene, suggesting that Hibiscus can be used as a material for the prevention and treatment of skin moisturizing and atopy, which have an important influence on tight junction.

• Transactions on Electrical and Electronic Materials
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• v.17 no.1
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• pp.21-24
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• 2016

A junction box used in a 3 kW photovoltaic power generation system plays a role in collecting and supplying the direct current voltage produced by photovoltaic modules to an inverter. It is also used for facilitating maintenance checks and protecting the module and inverter by keeping the voltage constant. As for the junction box, using it in a parallel connection creates a difference between the setup modules. In order to compensate, an inverse voltage diode is used. But the high-power created through the solar generator can be delivered to the inverter through the inverter regularly. Therefore, a component can break down due to excess heat. And consequently short circuits and electric leakage occurs. In this study, using a junction box that enabled the bypass of high electric power, it was possible to reduce heat generation by approximately 35℃ when compared to a standard junction box.

• Transactions on Electrical and Electronic Materials
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• v.17 no.6
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• pp.359-362
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• 2016

In the PV (Photovoltaic) power system, a junction box collects the DC voltage generated from the PV module and transfers it to the PCS (power conditioning system). The junction box prevents damage caused by the voltage difference between the serially connected PV modules and provides convenience while repairing or inspecting the PV array. In addition, the junction box uses the diode to protect modules from the inverse current when the PV power system and electric power system are connected for use. However, by using the reverse blocking diode, heat is generated within the junction box while generating electric power, which decreases the generating efficiency, and causes short circuit and electric leakage. In this research, based on the purpose of improving the performance of the PV module by decreasing the heat generation within the junction box, a junction box with a built-in bypass circuit was designed/manufactured so that a certain capacity of current generated from the PV module does not run through the reverse blocking diode. The manufactured junction box was used to compare the electric power and heating power generated when the circuit was in the bypass/non-bypass modes. It was confirmed that the electric power loss and heat generation indicated a decrease when the circuit was in the bypass mode.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.64.1-64.1
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• 2011

다중접합 태양전지는 흡수대역이 다른 juntion으로 구성되어, 각각의 태양전지 간의 전류정합(current matching)이 효율 향상에 중요하다. 본 실험에서는 Top cell에 i-a-Si:H(Thinckness:100nm), Middle cell에는 i-a-SiGe:H(Thickness:800nm)을 적용하였고, bottom cell에는 i-${\mu}c$-Si:H(Thickness:1800nm), 수광부의 p-layer에 에 SiOx을 이용하여 triple juntion amorphous silicon solar cell(삼중접합태양전지)을 구현하였다. 이를 최적화 시키기 위해 ASA simulation을 이용하여 각 Cell의 intrinsic layer의 밴드갭을 가변하였다. 가변 결과 i-a-Si:H : 1.85 eV, i-a-SiGe:H: 1.6 eV, i-${\mu}c$-Si:H: 1.4 eV에서 태양전지 효율 14.5 %을 기록 하였다. 본 연구를 통해 Triple juntion cell에서의 intrinsic layer의 밴드갭 최적화를 구현해 볼 수 있었다.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.86-86
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• 2012

The new approaches for silicon solar cell of new concept have been actively conducted. Especially, solar cells with wire array structured radial p-n junctions has attracted considerable attention due to the unique advantages of orthogonalizing the direction of light absorption and charge separation while allowing for improved light scattering and trapping. One-dimenstional semiconductor nano/micro structures should be fabricated for radial p-n junction solar cell. Most of silicon wire and/or pillar arrays have been fabricated by vapour-liquid-solid (VLS) growth because of its simple and cheap process. In the case of the VLS method has some weak points, that is, the incorporation of heavy metal catalysts into the growing silicon wire, the high temperature procedure. We have tried new approaches; one is electrochemical etching, the other is noble metal catalytic etching method to overcome those problems. In this talk, the silicon pillar formation will be characterized by investigating the parameters of the electrochemical etching process such as HF concentration ratio of electrolyte, current density, back contact material, temperature of the solution, and large pre-pattern size and pitch. In the noble metal catalytic etching processes, the effect of solution composition and thickness of metal catalyst on the etching rate and morphologies of silicon was investigated. Finally, radial p-n junction wire arrays were fabricated by spin on doping (phosphor), starting from chemical etched p-Si wire arrays. In/Ga eutectic metal was used for contact metal. The energy conversion efficiency of radial p-n junction solar cell is discussed.

• Toxicological Research
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• v.24 no.1
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• pp.1-9
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• 2008

Ptdlns(4,5)$P_2$ is a key cellular phosphoinositide that localizes in separate and distinctive pools in subcellular membrane and vesicular compartments. In membranes, Ptdlns(4,5)$P_2$ acts as a precursor to second messengers and is itself a main signaling and targeting molecule. Specific subcellular localization of type I PIP kinases directed by interacting with specific targeting module differentiates Ptdlns(4,5)$P_2$ production in a spatial and temporal manner. Several lines of evidences support the idea that Ptdlns(4,5)$P_2$ is generated in very specific pools in a spatial and temporal manner or by feeding Ptdlns(4,5)$P_2$ directly to effectors. In this concept, the interaction of PIPKI isoforms with a specific targeting module to allow precise subcellular targeting modulates highly specific Ptdlns(4,5)$P_2$ synthesis and channeling overall effectors. For instance, localization of PIPKI${\gamma}$661 to focal adhesions by an interaction with talin results in spatial and temporal production of Ptdlns(4,5)$P_2$, which regulates EGF-stimulated directional cell migration. In addition, Type $I{\gamma}$ PIPK is targeted to E-cadherin in cell adherence junction and plays a role in controlling dynamics of cell adherence junction and endocytosis of E-cadherin. Characterizing how PIP kinase isoforms are regulated by interactions with their targeting modules, as well as the mechanisms by which their product, Ptdlns(4,5)$P_2$, exerts its effects on cellular signaling processes, is crucial to understand the harmonized control of numerous cellular signaling pathways. Thus, in this review the roles of the Ptdlns(4)P(5) kinases and Ptdlns(4,5)$P_2$ were described and critically reviewed in terms of regulation of the E-cadherin trafficking, cell migration, and formation of cell adherence junction which is indispensable and is tightly controlled in epithelial-to-mesenchymal transition process.

• The Korea Journal of Herbology
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• v.32 no.3
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• pp.55-61
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• 2017

Objectives : The aim of this research was to determine the diverse effects of Lithospermi Radix Water Extract (LR) on human keratinocyte HaCaT cells, and to examine whether those effects could be applied to the human skin. Methods : We examined effect of LR on the cell viability of using the MTS assay in human keratinocyte HaCaT cells. The antioxidation effect of LR was analyzed relative to the well-known antioxidant resveratrol, using an ABTS assay. Quantitative RT-PCR analysis revealed that, in HaCaT cells, LR influenced the mRNA expression of tight-junction genes associated with skin moisturization. Furthermore, a wound-healing assay demonstrated altered cell migration in LR-treated HaCaT cells. Result : The cytotoxicity was confirmed to be higher in LR at a concentration of $800{\mu}g/m{\ell}$ using the MTS assay in HaCaT cells. In comparison to $100{\mu}M$ resveratrol, $1,600{\mu}g/m{\ell}$ LR showed either a similar or superior antioxidation effect. LR treatment in HaCaT cells reduced the mRNA expression levels of claudin 3, claudin 4, claudin 6, claudin 8, and ZO-2 to less than 0.80-fold, whereas JAM-A and Tricellulin mRNA expression level increased more than 1.33-fold. In addition, HaCaT cells migration was decreased to 83.9% by LR treatment. Conclusions : LR of antioxidation activity will have an anti-aging effect on the skin by reducing oxidative stress. Further studies are required to address the implications for human skin, given LR's effects of altering mRNA expression of tight junction-related gene and decreasing cell migration of HaCaT cells.

• Journal of The Korean Society of Integrative Medicine
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• v.9 no.2
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• pp.83-92
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• 2021

Purpose : Keratinocytes are the main cellular components involved in wound healing during re-epithelization and inflammation. Dysfunction of tight junction (TJ) adhesions is a major feature in the pathogenesis of various diseases. The purpose of this study was to identify the various effects of a Sparassis crispa water extract (SC) on HaCaT cells and to investigate whether these effects might be applicable to human skin. Methods : We investigated the effectiveness of SC on cell HaCaT viability using MTS. The antioxidant effect of SC was analyzed by comparing the effectiveness of ABTS to that of the well-known antioxidant resveratrol. Reverse-transcription quantitative polymerase chain reaction (qRT-PCR) is the most widely applied method Quantitative RT-PCR analysis has shown that SC in HaCaT cells affects mRNA expression of tight-junction genes associated with skin moisturization. In addition, Wound healing is one of the most complex processes in the human body. It involves the spatial and temporal synchronization of a variety of cell types with distinct roles in the phases of hemostasis, inflammation, growth, re-epithelialization, and remodeling. wound healing analysis demonstrated altered cell migration in SC-treated HaCaT cells. Results : MTS analysis in HaCaT cells was found to be more cytotoxic in SC at a concentration of 0.5 mg/㎖. Compared to 100 µM resveratrol, 4 mg/㎖ SC exhibited similar or superior antioxidant effects. SC treatment in HaCaT cells reduced levels of claudin 1, claudin 3, claudin 4, claudin 6, claudin 7, claudin 8, ZO-1, ZO-2, JAM-A, occludin, and Tricellulin mRNA expression by about 1.13 times. Wound healing analysis demonstrated altered cell migration in SC-treated HaCaT cells and HaCaT cell migration was also reduced to 73.2 % by SC treatment. Conclusion : SC, which acts as an antioxidant, reduces oxidative stress and prevents aging of the skin. Further research is needed to address the effects of SC on human skin given the observed alteration of mRNA expression of tight-junction genes and the decreased the cell migration of HaCaT cells.