• 약학회지
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• 제54권1호
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• pp.32-38
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• 2010

The aim of this study was to evaluate the effect of galangin towards hydrogen peroxide-induced DNA damage. The calf thymus DNA and Chinese Hamster Lung (CHL) cells were used to measure 8-hydroxy-2'-deoxyguanosine(8-OH2'dG) as an indicator of DNA oxidative damage using high performance liquid chromatography with electrochemical detection. Hydrogen peroxide in the presence of Fe(II) ion induced the formation of 8-OH2'dG in both calf thymus DNA and CHL cells. The DNA damage effects were enhanced by increasing the concentration of Fe(II) ion and inhibited by galangin. In the single cell gel electrophoresis (Comet assay), galangin and dl-a-tocopherol showed an inhibitory effect in CHL on hydrogen peroxide induced DNA single strand breaks. Galangin showed more potent activity than dl-$\alpha$-tocopherol under our experimental conditions. These results indicate that galangin can modify the action mechanisms of the oxidative DNA damage and may act as chemopreventive agents against oxidative stress.

• 한국전기전자재료학회논문지
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• 제34권5호
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• pp.382-385
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• 2021

Electrical poling is a crucial step to convert ferroelectrics to piezoelectrics. Nevertheless, no systematic investigation on the effect of poling has been reported. Given that the poling involves an alignment of spontaneous polarization, the condition for poling should be different when a material has an internal bias field that influences the domain stability. Here, we present the effect of poling profile on the dielectric and piezoelectric properties in Mn-doped Pb(Mg_1/3Nb_2/3)O₃-29 mol%PbTiO₃ single crystal with an internal bias field. We showed that both the dielectric permittivity and the piezoelectric coefficient were further enhanced when the poling procedure ends with a field application along the opposite direction to the internal bias field. We expect that the current finding would give a clue to understanding the true mechanism for the electrical poling.

• 한국해양공학회지
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• 제36권2호
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• pp.132-142
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• 2022

We investigate the performance of multi-body wave energy converters (WECs). This investigation considers multiple scattering of water waves by the buoys of a WEC under the generalized mode approach. Predominantly, the effect of a WEC's configuration on its energy extraction is studied in this research. First, single-row terminator and single-column attenuator arrays of vertical cylinders have been studied. The performance of these attenuator arrays shows that the wall effect induced by the periodic buoys influences the wave propagation and energy extraction in these WECs. Further studies show that a single-row terminator array of vertical cylinders performs better than the corresponding single-column attenuator array. Subsequently, multi-row terminator arrays of vertical cylinders are investigated by conducting a parametric study. This parametric study shows that the hydrodynamic property of three resonance phenomena makes energy extraction efficiency drop down, and the magnitude of energy extracted oscillates between the resonance points in these WECs. Finally, a 4×8 terminator array of vertical cylinders is studied to determine the effect of various d_x (x-directional distance between adjacent rows) within this WEC on its performance. In particular, this study enforces at least two equal d_x values within the 4×8 terminator array of vertical cylinders. It shows that a small value of this d_x leads to better energy extraction efficiency in some of these various d_x arrays than that of a corresponding regular array with the same d_x.

• Journal of Mechanical Science and Technology
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• 제15권7호
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• pp.823-830
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• 2001

The single fiber pull-out technique has been commonly used to characterize the mechanical behavior of fiber/matrix interface in fiber reinforced composite materials. In this study, an improved analysis considering the effect of thermal residual stresses in both radial and axial directions is developed for the single fiber pull-out test. It is found to have the pronounced effects on the stress transfer properties across the interface and the interfacial debonding behavior.

• 전기의세계
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• 제23권2호
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• pp.39-45
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• 1974

An analysis is developed for the torque characteristics of single-phase induction motors having variable shaded-pole angles. The machanism have two sets of stator windings which one set of stator fed from single-phase sources and other shorted by inserted external impedances. Thus, by phisically rotating one set of stator windings with respect to the other, the only shaded-kpole effect torque performance of a single- phase induction machine and its performance prediction to be expected of the optimum shaded-pole angle can be achieved.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집
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• pp.266-272
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• 2002

The stochiometric mixture of evaporating materials for the ZnIn$_2$S$_4$ single crystal thin film was prepared from horizontal furnace. To obtain the ZnIn$_2$S$_4$ single crystal thin film, ZnIn$_2$S$_4$ mixed crystal was deposited on throughly etched semi-insulating GaAs(100) in the Hot Wall Epitaxy(HWE) system. The source and substrate temperature were 610 $^{\circ}C$ and 450 $^{\circ}C$, respectively and the growth rate of the ZnIn$_2$S$_4$ single crystal thin film was about 0.5 $\mu\textrm{m}$/hr. The crystalline structure of ZnIn$_2$S$_4$ single crystal thin film was investigated by photo1uminescence and double crystal X-ray diffraction(DCXD) measurement. The carrier density and mobility of ZnIn$_2$S$_4$ single crystal thin film measured from Hall effect by van der Pauw method are 8.51${\times}$10$\^$17/ cm$\^$-3/, 291 $\textrm{cm}^2$/V$.$s at 293 $^{\circ}$K, respectively. From the photocurrent spectrum by illumination of perpendicular light on the c - axis of the ZnIn$_2$S$_4$ single crystal thin film, we have found that the values of spin orbit splitting ΔSo and the crystal field splitting ΔCr were 0.0148 eV and 0.1678 eV at 10 $^{\circ}$K, respectively. From the photoluminescence measurement of ZnIn$_2$S$_4$ single crystal thin film, we observed free excition (E$\_$X/) typically observed only in high quality crystal and neutral donor bound exciton (D$^{\circ}$,X) having very strong peak intensity. The full width at half maximum and binding energy of neutral donor bound excition were 9 meV and 26 meV, respectively. The activation energy of impurity measured by Haynes rule was 130 meV.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 추계학술대회 논문집 Vol.17
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• pp.171-174
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• 2004

The stochiometric $AgGaSe_2$ polycrystalline mixture of evaporating materials for the $AgGaSe_2$ single crystal thin film was prepared from horizontal furnace. To obtain the single crystal thin films, $AgGaSe_2$ mixed crystal and semi-insulating GaAs(100) wafer were used as source material and substrate for the Hot Wall Epitaxy (HWE) system, respectively. The source and substrate temperature were fixed at $630^{\circ}C$ and $420^{\circ}C$, respectively. The thickness of grown single crystal thin films is $2.1{\mu}m$. The single crystal thin films were investigated by photoluminescence and double crystal X-ray diffraction(DCXD) measurement. The carrier density and mobility of $AgGaSe_2$ single crystal thin films measured from Hall effect by van der Pauw method are $4.89{\times}10^{17}\;cm^{-3},\;129cm^2/V{\cdot}s$ at 293K, respectively. From the photocurrent spectrum by illumination of perpendicular light on the c - axis of the $AgGaSe_2$ single crystal thin film, we have found that the values of spin orbit splitting ${\Delta}S_o$ and the crystal field splitting ${\Delta}C_r$ were 0.1762 eV and 0.2494 eV at 10 K, respectively. From the photoluminescence measurement of $AgGaSe_2$ single crystal thin film, we observed free excition $(E_X)$ observable only in high quality crystal and neutral bound exciton $(D^o,X)$ having very strong peak intensity And, the full width at half maximum and binding energy of neutral donor bound excition were 8 meV and 14.1 meV, respectively. By Haynes rule, an activation energy of impurity was 141 meV.

• 가족자원경영과 정책
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• 제21권2호
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• pp.25-50
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• 2017

Recently, concern about family safety is rising again as an important issue with the context of family healthiness and well-being in Korean society despite of the dramatic economic growth. The purpose of this study is to examine the status of family safety of singles and single-parent households and to investigate the effect of social capital on the level of their family safety. Data are from the 10th wave of Korea Welfare Panel Study analysing one-person households(N=2,017) and single-parent households(N=172). One-person households were categorized as three groups by age(the youths/middle-aged/the elderly) and single-parent households were also three by family types(mother-child/fahter-child/grandparent-child). The major results were as follows: First, the mean of family safety index was highest among middle-aged, while single youths had the fewest problems in terms of family safety. Second, social capital was found to vary by family structure. In the one-person households, all the levels of the social capital variables, including trust, bond, acceptance, and participation, differed significantly; only two variables, bond and embracement, differed in the single-parent households. Third, social capital differed between the low-income households and others significantly. Forth, the positive effects of social capital on overcoming family safety problems were investigated. In conclusion, social capital represents an alternative resource for overcoming economic hardship for low-income one-person/single-parent households, especially for middle-aged singles and father-child single-parent households. Based on these empirical results, theoretical implications were discussed with regard to family policy and programs.

• 센서학회지
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• 제17권6호
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• pp.437-446
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• 2008

Single crystalline ${ZnIn_2}{Se_4}$ layers were grown on thoroughly etched semi-insulating GaAs (100) substrate at $400^{\circ}C$ with hot wall epitaxy (HWE) system by evaporating ${ZnIn_2}{Se_4}$ source at $630^{\circ}C$. The crystalline structure of the single crystalline thick films was investigated by the photoluminescence (PL) and Double crystalline X-ray rocking curve (DCRC). The carrier density and mobility of ${ZnIn_2}{Se_4}$ single crystalline thick films measured from Hall effect by van der Pauw method are $9.41{\times}10^{16}cm^{-3}$ and $292cm^2/V{\cdot}s$ at 293 K, respectively. The temperature dependence of the energy band gap of the ${ZnIn_2}{Se_4}$ obtained from the absorption spectra was well described by the Varshni's relation, $E_g(T)$=1.8622 eV-$(5.23{\times}10^{-4}eV/K)T^2$/(T+775.5 K). After the as-grown ${ZnIn_2}{Se_4}$ single crystalline thick films was annealed in Zn-, Se-, and In-atmospheres, the origin of point defects of ${ZnIn_2}{Se_4}$ single crystalline thick films has been investigated by the photoluminescence (PL) at 10 K. The native defects of $V_{Zn}$, $V_{Se}$, $Zn_{int}$, and $Se_{int}$ obtained by PL measurements were classified as a donors or acceptors type. And we concluded that the heat-treatment in the Se-atmosphere converted ${ZnIn_2}{Se_4}$ single crystalline thick films to an optical p-type. Also, we confirmed that In in ${ZnIn_2}{Se_4}$/GaAs did not form the native defects because In in ${ZnIn_2}{Se_4}$ single crystalline thick films existed in the form of stable bonds.

• 한국전기전자재료학회논문지
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• 제15권11호
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• pp.923-932
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• 2002

A stoichiometric mixture of evaporating materials for CdIn$\_$2/S$\_$4/ single crystal thin films was prepared from horizontal furnace. To obtain the single crystal thin films, CdIn$\_$2/S$\_$4/ mixed crystal was deposited on thoroughly etched semi-insulating GaAs(100) substrate by hot wall epitaxy(HWE) system. The source and substrate temperatures were 630 $\^{C}$ and 420 $\^{C}$, respectively. The crystalline structure of single crystal thin films was investigated by the photoluminescence and double crystal X-ray diffraction(DCXD). The carrier density and mobility of CdIn$\_$2/S$\_$4/ single crystal thin films measured from Hall effect by van der Pauw method are 9.01$\times$10$\^$16/ cm$\^$-3/ and 219 ㎠/V$.$s at 293 K, respectively. From the optical absorption measurement, the temperature dependence of energy band gap on CdIn$\_$2/S$\_$4/ single crystal thin films was found to be Eg(T) ＝ 2.7116 eV - (7.74 $\times$ 10$\^$-4/ eV) T$\^$2//(T＋434). After the as-grown CdIn$\_$2/S$\_$4/ single crystal thin films was annealed in Cd-, S-, and In-atmospheres, the origin of point defects of CdIn$\_$2/S$\_$4/ single crystal thin films has been investigated by the photoluminescence(PL) at 10 K. The native defects of V$\_$cd/, V$\_$s/, Cd$\_$int/ and S$\_$int/ obtained by PL measurements were classified as donors or accepters type. And we concluded that the heat-treatment in the S-atmosphere converted CdIn$\_$2/S$\_$4/ single crystal thin films to an optical p-type. Also, we confirmed that In in CdIn$\_$2/S$\_$4/GaAs did not from the native defects because In in CdIn$\_$2/S$\_$4/ single crystal thin films existed in the form of stable bonds.