• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.276-276
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• 2010

Localized surface plasmon resonance (LSPR) has been explored recently as a promising approach to increase energy conversion efficiency in photovoltaic devices, particularly for thin film hydrogenated amorphous silicon (a-Si:H) solar cells. The LSPR is frequently excited via an electromagnetic (EM) radiation in proximate metallic nanostructures and its primary con sequences are selective photon extinction and local EM enhancement which gives rise to improved photogeneration of electron-hole (e-h) pairs, and consequently increases photocurrent. In this work, high-dielectric-constant (k) $ZrO_2$ (refractive index n=2.22, dielectric constant $\varepsilon=4.93$ at the wavelength of 550 nm) is proposed as spacing layer to enhance the LSPR for application to the thin film silicon solar cells. Compared to excitation of the LSPR using $SiO_2$ (n=1.46, $\varepsilon=2.13$ at the wavelength of 546.1 nm) spacing layer with Au nanoparticles of the radius of 45nm, that using $ZrO_2$ dielectric shows the advantages of(i) ~2.5 times greater polarizability, (ii) ~3.5 times larger scattering cross-section and ~1.5 times larger absorption cross-section, (iii) 4.5% higher transmission coefficient of the same thickness and (iv) 7.8% greater transmitted electric filed intensity at the same depth. All those results are calculated by Mie theory and Fresnel equations, and simulated by finite-difference time-domain (FDTD) calculations with proper boundary conditions. Red-shifting of the LSPR wavelength using high-k $ZrO_2$ dielectric is also observed according to location of the peak and this is consistent with the other's report. Finally, our experimental results show that variation of short-circuit current density ($J_{sc}$) of the LSPR enhanced a-Si:H solar cell by using the $ZrO_2$ spacing layer is 45.4% higher than that using the $SiO_2$ spacing layer, supporting our calculation and theory.

• Korean Journal of Optics and Photonics
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• v.17 no.5
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• pp.461-468
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• 2006

Optical characteristics in polymer films of MEH-PPV/DFPP blends were for the first time investigated. DFPP (N, N'-diperfluorophenyl-3,4,9,10-perylenetetracarboxylic diimide) used here was a novel n-type polymer, which had good stability in air and solubility in common solvents. For a 1:9 DFPP:MEH-PPV blend, highly efficient quenching of photoluminescence (PL) was observed. In addition, the photocurrent responses of these MEH-PPV/DFPP photovoltaic cells were measured. When the light intensity was $50mW/cm^2$, short-circuit photocurrent densities were two times higher than those of single layer MEH-PPV devices.

• Journal of the Korean Electrochemical Society
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• v.22 no.2
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• pp.69-78
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• 2019

Lithium metal anode with the highest theoretical capacity to replace graphite anodes are being reviewed. However, the dendrite growth during repeated oxidation/reduction reaction on lithium metal surface, which results in poor cycle performance and safety issue has hindered its successful implementation. In our previous work, we solved this problem by using surface modification technique whereby a surface pattern on lithium metal anode is introduced. Although the micro-patterned Lithium metal electrode is beneficial to control Li metal deposition efficiently, it is difficult to control the mossy-like Li granulation at high current density ($>2.0mA\;cm^{-2}$). In this study, we introduce vinylene carbonate (VC) electrolyte additive on micro patterned lithium metal anode to suppress the lithium dendrite growth. Owing to the synergetic effect of micro-patterned lithium metal anode and VC electrolyte additive, lithium dendrite at a high current density is dense. As a result, we confirmed that the cycle performance was further improved about 6 times as compared with the reference electrode.

• Applied Chemistry for Engineering
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• v.22 no.2
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• pp.190-195
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• 2011

To investigate the photon-trapping effect and scattering layer effect of $TiO_2$ multi-layer in dye-sensitized solar cell (DSSC) and the degree of recombination of electrons at the electrode treated $TiCl_4$, we formed electrodes of different conditions and obtained the most optimal electrode conditions. To estimate characteristics of the cell, IV curve, UV-Vis spectrophotometer, electrochemical impedance spectroscopy (EIS) and incident photon-to-current conversion efficiency (IPCE) were measured. As a result, we confirmed that the multi-layer's efficiency was higher than that of monolayer in the IV curve and the performance of $TiCl_4$ treated electrode was increased according to decreasing the impedance of EIS. Among several conditions, the efficiency of the cell with scattering layer is higher than that of a layer with the base electrode about 19%. Because the light scattering layer enhances the efficiency of the transmission wavelength and has long electron transfer path. Therefore, the value of the short circuit current increases approximately 10% and IPCE in the maximum peak also increases about 12%.

• Journal of Ginseng Research
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• v.45 no.1
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• pp.66-74
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• 2021

Background: Abnormal chloride (Cl-) transport has a detrimental impact on mucociliary clearance in both cystic fibrosis (CF) and non-CF chronic rhinosinusitis. Ginseng is a medicinal plant noted to have anti-inflammatory and antimicrobial properties. The present study aims to assess the capability of red ginseng aqueous extract (RGAE) to promote transepithelial Cl- secretion in nasal epithelium. Methods: Primary murine nasal septal epithelial (MNSE) [wild-type (WT) and transgenic CFTR-/-], fisher-rat-thyroid (FRT) cells expressing human WT CFTR, and TMEM16A-expressing human embryonic kidney cultures were utilized for the present experiments. Ciliary beat frequency (CBF) and airway surface liquid (ASL) depth measurements were performed using micro-optical coherence tomography (μOCT). Mechanisms underlying transepithelial Cl- transport were determined using pharmacologic manipulation in Ussing chambers and whole-cell patch clamp analysis. Results: RGAE (at 30㎍/mL of ginsenosides) significantly increased Cl- transport [measured as change in short-circuit current (ΔISC = ㎂/㎠)] when compared with control in WT and CFTR-/- MNSE (WT vs control = 49.8±2.6 vs 0.1+/-0.2, CFTR-/- = 33.5±1.5 vs 0.2±0.3, p < 0.0001). In FRT cells, the CFTR-mediated ΔISC attributed to RGAE was small (6.8 ± 2.5 vs control, 0.03 ± 0.01, p < 0.05). In patch clamp, TMEM16A-mediated currents were markedly improved with co-administration of RGAE and uridine 5-triphosphate (8406.3 +/- 807.7 pA) over uridine 5-triphosphate (3524.1 +/- 292.4 pA) or RGAE alone (465.2 +/- 90.7 pA) (p < 0.0001). ASL and CBF were significantly greater with RGAE (6.2+/-0.3 ㎛ vs control, 3.9+/-0.09 ㎛; 10.4+/-0.3 Hz vs control, 7.3 ± 0.2 Hz; p < 0.0001) in MNSE. Conclusion: RGAE augments ASL depth and CBF by stimulating Cl- secretion through CaCC, which suggests therapeutic potential in both CF and non-CF chronic rhinosinusitis.

• Journal of the Korean Electrochemical Society
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• v.24 no.4
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• pp.100-105
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• 2021

Recently, all-solid-state batteries have attracted much attention to improve safety of rechargeable lithium batteries, but the solid-state batteries of conductive ceramics or solid polymer electrolytes show poor electrochemical properties because of several problems such as high interfacial resistance and undesired reactions. To solve the problems of the reported all-solid-state batteries, a hybrid solid electrolyte is suggested, in this study, NASICON-type nanoparticle Li_1.5Al_0.5Ti_1.5P₃O₁₂ (LATP) conductive ceramic, PVdF-HFP, and a carbonate-based liquid electrolyte were composited to prepare a quasi-solid electrolyte. The hybrid solid electrolyte has a high voltage stability of 5.6 V and shows an suppress effect of lithium dendrite growth in the stripping-plating test. The LiNi_0.83Co_0.11Mn_0.06O₂ (NCM811)-based battery with the hybrid solid electrolyte exhibits a high discharge capacity of 241.5 mAh/g at a high charge-cut-off voltage of 4.8V and stable electrochemical reaction. The NCM811-based battery also shows 139.4 mAh/g discharge capacity without short circuit or explosion at 90℃. Therefore, the LATP-based hybrid solid electrolyte can be an effective solution to improve the safety and electrochemical properties of rechargeable lithium batteries.

• Journal of Appropriate Technology
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• v.7 no.2
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• pp.196-205
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• 2021

As industrial safety increases, various industrial accident prevention technologies using smart factory technology are being studied. However, small and medium enterprises (SMEs), which account for the majority of industrial accidents, are having difficulties in preventing industrial accidents by applying these smart factory technologies due to practical problems. In this study, customized monitoring and warning systems for each type of industrial accident were developed and applied to the actual field. Through this, we demonstrated industrial accident prevention technology through appropriate smart factory technology used by SMEs. A customized monitoring system using vision, current, temperature, and gas sensors was established for the four major disaster types: worker body access, short circuit and overcurrent, fire and burns due to high temperature, and emission of hazardous gas. In addition, a notification method suitable for each work environment was applied so that the monitored risk factors could be recognized quickly, and real-time data transmission and display enabled workers and managers to understand the disaster risk effectively. Through the application and demonstration of these appropriate smart factory technologies, the spread of these industrial safety technologies is to be discussed.

• Journal of the Korea Society of Computer and Information
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• v.27 no.2
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• pp.153-161
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• 2022

Physical activities are decreasing and sitting time is increasing due to the automation, smartization, and intelligence of necessary household items throughout daily life. Recent healthcare studies have reported that the likelihood of obesity, diabetes, cardiovascular disease, and early death increases in proportion to sitting time. In this paper, we develop a sitting posture correction cushion in real time using capacitive pressure sensor based on conductive textile. It develops a pressure sensor using conductive textile, a key component of the posture correction cushion, and develops a low power-based pressure measurement circuit. It provides a function to transmit sensor values measured in real time to smartphones using BLE short-range wireless communication on the posture correction cushion, and develops a mobile application to check the condition of the sitting posture through these sensor values. In the mobile app, you can visualize your sitting posture and check it in real time, and if you keep it in the wrong posture for a certain period of time, you can notify it through an alarm. In addition, it is possible to visualize the sitting time and posture accuracy in a graph. Through the correction cushion in this paper, we experiment with how effective it is to correct the user's posture by recognizing the user's sitting posture, and present differentiation and excellence compared to other product.

• Korean Journal of Materials Research
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• v.32 no.11
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• pp.481-488
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• 2022

The Cu₂ZnSn(S_xSe_1-x)₄ (CZTSSe) absorbers are promising thin film solar cells (TFSCs) materials, to replace existing Cu(In,Ga)Se₂ (CIGS) and CdTe photovoltaic technology. However, the best reported efficiency for a CZTSSe device, of 13.6 %, is still too low for commercial use. Recently, partially replacing the Zn²⁺ element with a Cd²⁺element has attracting attention as one of the promising strategies for improving the photovoltaic characteristics of the CZTSSe TFSCs. Cd²⁺ elements are known to improve the grain size of the CZTSSe absorber thin films and improve optoelectronic properties by suppressing potential defects, causing short-circuit current (J_sc) loss. In this study, the structural, compositional, and morphological characteristics of CZTSSe and CZCTSSe thin films were investigated using X-ray diffraction (XRD), X-ray fluorescence spectrometer (XRF), and Field-emission scanning electron microscopy (FE-SEM), respectively. The FE-SEM images revealed that the grain size improved with increasing Cd²⁺ alloying in the CZTSSe thin films. Moreover, there was a slight decrease in small grain distribution as well as voids near the CZTSSe/Mo interface after Cd²⁺ alloying. The solar cells prepared using the most promising CZTSSe absorber thin films with Cd²⁺ alloying (8 min. 30 sec.) exhibited a power conversion efficiency (PCE) of 9.33 %, J_sc of 34.0 mA/cm², and fill factor (FF) of 62.7 %, respectively.

• Applied Chemistry for Engineering
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• v.22 no.1
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• pp.15-20
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• 2011

Poly[2,3-dimethyl-5,8-dithiophene-2-yl-quinoxaline-alt-9,9-dihexyl-9H-fluorene] (PFTQT) and poly[2,3-dimethyl-5,8-dithiophen-2-yl-quinoxaline-alt-10-hexyl-10H-phenothiazine (PPTTQT) based on 2,3-dimethyl-5,8-dithiophen-2-yl-quinoxaline weresynthesized by Suzuki coupling reaction. All polymers were soluble in common organic solvents such as chloroform, chlorobenzene, o-dichlorobenzene, tetrahydrofuran (THF) and toluene. The maximum absorption wavelength and band gap of PFTQT were 440 nm and 2.30 eV, and PPTTQT were 445 nm and 2.23 eV, respectively. The HOMO and LUMO energy level of PFTQT were -6.05 and -3.75 eV, and PPTTQT were -5,89 and -3.66 eV, respectively. The organic photovoltaic devices based on the blend of polymer and PCBM (1 : 2 by weight ratio) were fabricated. Efficiencies of devices were 0.24% (PFTQT) and 0.16% (PPTTQT), respectively. The short circuit current density ($J_{sc}$), fill factor (FF), and open circuit voltage ($V_{oc}$) of the device with PFTQT were $0.97mA/cm^2$, 29% and 0.86 V, and the device based on PPTTQT were $0.80mA/cm^2$, 28% and 0.71 V, 31% and 0.71 V, respectively, under air mass (AM) 1.5 G and 1 sun condition ($100mA/cm^2$).