• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.28-29
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• 2006

When photovoltaic module is used for a long time, its performance decreases due to several reasons. In this paper, we focus on the possibilities mainly contributing to the degraded efficiency of the polycrystalline silicon photovoltaic modules. The analysis is based on the modules that have been used for 15 years. These are two main reasons that cause the efficiency degradation, the corrosion and thermal decomposition. The former phenomenon of electrode is mainly due to the moisture from damaged back sheet in some module. However the other reason of the degraded efficiency comes from the thermal decomposition, which can not be observed from the outside but only by experiment. In this study, the comparison between the efficiency of normal modules and degradation modules is presented. Module having degraded cell was seen to cause increase of series resistance by about 80%, in comparison to normal samples efficiency which reduce by about 20%. This study shows that the effects of series resistances on module performance are critical. These effects must be understood and taken into consideration when analyzing performance degradation.

• Bulletin of the Korean Chemical Society
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• v.8 no.3
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• pp.179-183
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• 1987

Reactions of $Rh(ClO_4)(CO)(AsPh_3)_2$ with unsaturated nitriles and aldehyde, L, produce a series of new cationic rhodium (I) complexes, $[RhL(CO)(AsPh_3)_2]ClO_4$ (L = $CH_2$ = CHCN, $CH_2$ = C($CH_3$)CN, trans-$CH_3CH$ = CHCN, $CH_2$ = CH$CH_2$CN, trans-$C_6H_5CH$ = CHCN, and trans-$C_6H_5CH$ = CHCHD) where L are coordinated through the nitrogen and oxygen, respectively but not through the ${\pi}$-system of the olefinic group. Dissociation constants for the reaction, $[RhL(CO)(AsPh_3)_2]ClO_4$ $\rightleftharpoons$ $Rh(ClO_4)(CO)(AsPh_3)_2$ + L, have been measured to be $1.20{\times}10^{-4}$ M (L = $CH_2$ = CHCN), $1.05{\times}10^{-4}$ M (L = $CH_2$ = C($CH_3$)CN, $3.26{\times}10^{-5}$ M (L = trans-$CH_3$CH = CHCN) and $6.45{\times}10^{-5}$ M (L = $CH_2$ = CH$CH_2$CN) in chlorobenzene at $25^{\circ}C, and higher than those of triphenylphosphine complexes, $[RhL(CO)(AsPh_3)_2]ClO_4$ where L are the corresponding nitriles that are coordinated through the nitrogen atom. The differences in dissociation constants seem to be predominantly due to the differences in ${\Delta}H$ (not due to the differences in ${\Delta}S$). The weaker Rh-N (unsaturated nitriles) bonding in $AsPh_3$ complexes than in $PPh_3$ complexes (based on ${\Delta}H$ values) suggests that the unsaturated nitriles in 2∼5 are good ${\sigma}$-donor and poor ${\pi}$-acceptor.

• Journal of Forest and Environmental Science
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• v.18 no.1
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• pp.53-60
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• 2001

2kg of the dried leaves of chamaecyparis obtusa Endlicher were ground, extracted with acetone-$H_2O$(7:3, v/v), concentrated, and fractionated with a series of hexane, $CH_2Cl_2$, EtOAc and water on a separatory funnel. Each fraction was freeze dried to give dark-brown powder and a EtOAc soluble portion of the powder was chromatographed on a Sephadex LH-20 column using a series of aqueous methanol and ethanol-hexane mixture as eluents. Spectrometric analyses such as NMR and FAB-MS including TLC were performed to characterize the structures of the isolated compounds. The leaves of chamaecyparis obtusa Endlicher contained a large amount of taxifolin-3-O-${\beta}$-D-xylopyranoside and (+)-catechin in addition to a small amount of quercetin-3-O-${\alpha}$-L-rhamnopyranoside.

• Korean Journal of Microbiology
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• v.33 no.2
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• pp.105-110
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• 1997

Ustilago maydis strains (A-series and SH-series) containg virus or viral dsRNAs were artificially mated in corn seedling to generate 6 progeny strains, designated A23, A45, A21l, A31O, SH24 and SH61O. The dsRNA patterns of progeny strains were identical to those of the parental strains and there was no molecular exclusion mechanism among dsRNAs of parental strains. Virus particles were purified from 6 progeny strains and viral dsRNAs were analyzed on 5% PAGE. There was no mixed encapsidation between virus or dsRNAs of parental strains. Progeny strain SH6l4 produced toxin which inhibits the growth of SH9, SHIO and SH11. Likewise, toxins from A310 and SH24 inhibited growth of the SH11 strains. These results indicate that the presence of different types of dsRNA does not interfere the expression of toxin gene.

• Membrane and Water Treatment
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• v.1 no.4
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• pp.297-316
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• 2010

Membrane fouling is one of the major operational concerns of membrane processes which results in loss of productivity. This paper investigates the ultrafiltration (UF) results of synthetic oil-in-water (o/w) emulsion using flat sheets of polysulfone (PSf) membrane synthesized with four different compositions. The aim is to identify the mechanisms responsible for the observed permeate flux reduction with time for different PSf membranes. The experiments were carried out at four transmembrane pressures i.e., 68.9 kPa, 103.4 kPa, 137.9 kPa and 172.4 kPa. Three initial oil concentrations i.e., 75 $mgL^{-1}$, 100 $mgL^{-1}$ and 200 $mgL^{-1}$ were considered. The resistance-in-series (RIS) model was applied to interpret the data and on that basis, the individual resistances were evaluated. The significances of these resistances were studied in relation to parameters, namely, transmembrane pressure and initial oil concentration. The total resistance to permeate flow is found to increase with increase in both transmembrane pressure and initial oil concentration while for higher oil concentration, resistance due to concentration polarization is found to be the prevailing resistance. The applicability of the constant pressure filtration models to the experimental data was also tested to explain the blocking process. The study shows that intermediate pore blocking is the dominant mechanism at the initial period of UF while in the later period, the fouling process is found to approach cake filtration like mechanism. However, the duration of pore blocking mechanism is different for different membranes depending on their morphological and permeation properties.

• Journal of Korean Society of Disaster and Security
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• v.14 no.4
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• pp.1-7
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• 2021

Although the working environment has changed significantly compared to the past, such as the implementation of the five-day work week and the aging of the population, it is not reflected in the current industrial accident index calculation such as frequency rate, severity rate, and safe T-score. In this study, statistical data were used to understand time-series trends such as increase in life expectancy, working age, shortening of working hours, and average age of death by accident. As a result of time series trend analysis of statistical data, life expectancy increased to 83.3 years, and the legal working age was raised to 65 years due to the aging of the population. Also, with the advent of the 5-day work week since 2001, the average annual working hours decreased to 2008.1 hours. It can be confirmed through statistical data that these phenomena are applied to the current working environment due to a complex action, and these environmental changes affect the calculation results of the industrial accident index.

• Polymer(Korea)
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• v.24 no.4
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• pp.477-487
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• 2000

A series of poly(L-lactic acid) (PLLA)/poly($\beta$-hydroxynonanoate) (PHN) blend were prepared to study the miscibility and the crystallization behaviors. The thermal behaviors and characterization of PLLA/PHN blends Were studied using differential scanning calorimetry (DSC), XRD and polarizing optical microscopy (POM). The PLLA and PHN are partially miscible in amorphous region. The crystallinity of PLLA increased as the content of PHN increased, and T$_{g}$, T$_{c}$, and T$_{m}$ of PLLA shift as the content of PHN increased. Moreover, the number of PLLA spherulite increased as the content of PHN increased in the POM experiment. Thus, PHN acted as a nucleating agent to PLLA.

• Journal of the Korean Chemical Society
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• v.27 no.4
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• pp.255-261
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• 1983

Several new $[Pd(L)X_2]$ complexes have been prepared with aminophosphines (L) such as trans-1,2-bis[diphenylphosphino)amino]cyclohexane and 1,2-bis[(diphenylphosphino) amino] propane that contain phosphorus atom as ${\pi}$-electron acceptor, and the bond character of complexes have been investigated by means of infrared and electronic spectroscopy. It was found that thiocyanate ions are N-coordinated possibly due to the steric and electronic influence of the phosphorus atom in aminophosphines that formed seven-membered chelate rings, and that spectrochemical series that is derived from the electronic spectra of the complexes is $NCS^- > Cl^- > Br^- > I^-$

• Journal of electromagnetic engineering and science
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• v.11 no.4
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• pp.298-303
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• 2011

A capsular endoscope (CE) for inspection of the large intestine requires a motor for backward navigation against the autonomous travel in the intestine. This study proposes an HF power system for generating a magnetic field and for delivering wireless power to the internal or implanted medical devices. The magnetic field is generated by a wound coil (L) around a wooden frame, and the current is driven to the coil through a resonating capacitor (C). The characteristics of the resonance frequency shifting of the L-C series circuit are analyzed. A stable magnetic field intensity in the field coil is maintained by a specially designed frequency tracking system that automatically follows the L-C resonance frequency. Testing confirmed that the oscillation system tracks well the parameter changes of the electric components caused by the operating conditions or environmental variations.

• Journal of Life Science
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• v.16 no.7 s.80
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• pp.1181-1187
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• 2006

HS-1580 series (HS-1580, HS-1581, HS-1582) can produce anti-imflammatory effects were synthesized from the marine algae extraction in 2,3,6-tribromo-4,5-dihydroxy benzyl methyl ether (TDB). Raw 264.7 cells were pre-treated with $1{\mu}g/{\mu}l$ lipopolysaccharide (LPS) and later treated with HS-1580 series. These cells of inflammatory mediators were tested as well. Nitric oxide (NO) is related to autoimmune disease and is produced by inducible NOS (iNOS). When treated with HS-1580 series, the product of NO will reduce in a dose-dependent manner. HS-1580 series significantly inhibit the iNOS protein expression. Cyclooxygenase (COX) involves with the various physiologic events and catalyzes in prostaglandin. HS-1580 series also inhibit the COX-2 protein expression as well as pro-inflammatory cytokines production such as tumor necrosis $factor-{\alpha}\;(TNF-{\alpha})\;and\;interluekin-1{\alpha]\;(IL-1{\beta})$. These upcoming results suggest that HS-1580 series have anti-inflammatory efforts in Raw 264.7 cells by inhibiting such as iNOS, COX-2, $TNF-{\alpha}\;and\;IL-1{\beta}$ as inflammatory mediators.