• Rapid Communication in Photoscience
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• 제1권2호
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• pp.35-37
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• 2012

Photoinduced electron-transfer process of 1,8-naphthalimide-linker-trimethylsilane (NI-O3-TMS, O3 = 3,6,9-trioxaundecyl) and NI-O3 has been investigated using the transient absorption measurements in $CH_3CN$ and $CH_3CN/H_2O$. The excitation of NI-O3-TMS in $CH_3CN$ produced the NI radical anion ($NI^{{\cdot}-}$) with a transient absorption band around 413 nm, via the intermolecular electron-transfer between NI moieties in the excited singlet state. In contrast, in a protic polar solvent mixture of $CH_3CN/H_2O$, a proton abstraction process occurred from $NI^{{\cdot}-}$ to generate the NI ketyl radical ($NIH^{\cdot}$), which showed a transient absorption band around 405 nm. The decay time constants of $NIH^{\cdot}$ were quite long compared to those of $NI^{{\cdot}-}$ in $CH_3CN$.

• 한국표면공학회지
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• 제53권2호
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• pp.59-66
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• 2020

Effects of Na₂SiO₃ concentration added into 0.1 M NaOH + 0.05 M NaF solution on the formation behavior and properties of PEO films on AZ91 Mg alloy were investigated under 1200 Hz of alternating current (AC) by voltage-time curves, in-situ observation of arc generation behavior and measurements of film thickness, surface roughness and micro vickers hardness. In the absence of Na₂SiO₃ in the 0.1 M NaOH + 0.05 M NaF solution, about 4 ㎛ thick PEO film was formed within 1 min and then PEO film did not grow but white spots were formed by local burning. Addition of Na₂SiO₃ up to 0.2 M caused more increased formation voltage and growth of PEO film with uniform generation of arcs. Addition of Na₂SiO₃ from 0.2 M to 0.4 M showed nearly the same voltage-time behavior and uniform arc generation. Addition of Na₂SiO₃ more than 0.5 M resulted in a decrease of formation voltage and non-uniform arc generation due to local burning. PEO film growth rate increased with increasing added Na₂SiO₃ concentration but maximum PEO film thickness was limited by local burning if added Na₂SiO₃ concentration is higher than 0.5 M. Surface roughness of PEO film increased with increasing added Na₂SiO₃ concentration and appeared to be proportional to the PEO film thickness. PEO film hardness increased with increasing added Na₂SiO₃ concentration and reached a steady-state value of about 930 H_V at more than 0.5 M of added Na₂SiO₃ concentration.

• 청정기술
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• 제18권4호
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• pp.419-425
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• 2012

본 연구는 황 원소와 질소 원소가 도핑된 이산화티타늄의 특성을 조사하고 8-와트(W) 일반 램프와 가시광선 영역의 발광 다이오드 조사 조건에서 낮은 농도수준의 가스상 이소프로필 알코올(isopropyl alcohol, IPA)의 광촉매적 분해능에 대하여 조사하였다. 또한, 이소프로필 알코올의 광촉매 분해시 발생되는 아세톤의 생성에 대해서도 조사하였다. 황 원소와 질소 원소가 도핑된 이산화티타늄의 표면 조사결과, 두 촉매들은 가시광선 조사(visible light-emitting-diodes, LEDs)에 의해 효율적으로 활성화될 수 있는 것으로 나타났다. 두 촉매 모두에 대하여, 공기 유량이 감소함에 따라 이소프로필 알코올의 제거 효율이 증가하는 것으로 나타났다. 황 도핑 촉매의 경우, 유량이 0.1 L $min^{-1}$일 때 이소프로필 알코올 제거효율이 거의 100%로 나타난 반면에 유량이 2.0 L $min^{-1}$일 때 이소프로필 알코올 제거효율은 39%로 나타났다. 질소 도핑 촉매의 경우에는, 유량이 0.1 L $min^{-1}$일 때 이소프로필 알코올 제거효율이 거의 100%로 나타난 반면에 유량이 2.0 L $min^{-1}$일 때 이소프로필 알코올 제거효율은 90% 이상으로 나타났다. 이소프로필 알코올 제거 효율과는 달리, 유량 감소에 따라 아세톤 생성율은 감소하는 것으로 나타났다. 결과적으로, 아세톤 생성을 최소화하고 이소프로필 알코올 제거 효율을 높이기 위해서는 질소 도핑 촉매를 낮은 유량 조건에서 작동시키는 것이 나은 것으로 나타났다. 또한, 이소프로필 알코올 제거를 위해 가시광선 조사 발광 다이오드보다 8-와트 일반램프가 효율적인 것으로 나타났다.

• 한국세라믹학회지
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• 제33권6호
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• pp.672-678
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• 1996

The relationship between domain switching and acoustic emission (AE) during poling was investigated using the tetragonal ferroelectric ceramics with composition of (Pb,La)TiO3+0.01MnO2 The amount of AE generation during poling increased with increasing dc electric field and raising temperature. It was confirmed that the change of the amount of AE generation with poling condition resulted from the difference of the amount of 90$^{\circ}$ domain switching and total amount of AE generation for 10 minutes was approximately proportional to the amount of 90$^{\circ}$domain switching. The A generations of two specimens which have different tetragonality rations(c/s rations) 15 at% and 24at% La-doped were also investigated. The sample with c/a ratio of 1.012 where 90$^{\circ}$ domains are dominate had larger amount of AE generation and 90$^{\circ}$ domain switching compared with the sample with c/a ratio of 1.004 where 180$^{\circ}$ domains are dominant.

• 말소리와 음성과학
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• 제9권2호
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• pp.39-51
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• 2017

The current study aims to investigate the effect of sociolinguistic factors such as region, generation and gender on the acoustic properties of Korean high and mid back vowels. We analyzed the vowel productions of one hundred twenty-eight subjects from the Korean Standard Speech Database, chosen to represent the different possible combinations of region, generation, and gender. The results reveal a chain-like shift in the back vowels. Unlike previous studies that have reported /o/-/u/ becoming closer as a result of a decreasing F1 in /o/, we found that the distance between the two vowels is decided more by the changing F2 in /u/. Also, the F2 of /u/ and /ɯ/, and the F2 of /ʌ/ and F1 of /o/ appear to move in tandem. Lastly, this study suggests that the reason the vowel changes differ across gender and regional dialects could be because they are all converging on to the standard Korean.

• 한국물환경학회지
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• 제27권2호
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• pp.194-199
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• 2011

This study has been carried out to evaluate the performance of $PbO_2$ electrode for the purpose of degradation of N,N-Dimethyl-4-nitrosoaniline (RNO, indicator of OH radical), generation of ozone and decolorization of Rhodamine B (RhB) in water. The effect of the applied current (0.2~1.2 A), electrolyte type (NaCl, KCl and $Na_2SO_4$), electrolyte concentration (0.0~2.5 g/L) and solution pH (3~11) were evaluated. Experimental results showed that RhB and RNO removal were increased with the increase of current, NaCl dosage and decrease of pH. Ozone generation tendencies appeared with the almost similar to the RhB and RNO degradation, except of solution pH (Ozone generation was increased with increase of pH). Optimum current for RhB degradation and consumption of electric power was 1.0 A. The RhB degradation with Cl type electrolyte were higher than that with the sulfate type. Optimum NaCl dosage for RhB degradation was 1.0 g/L.

• 한국진공학회지
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• 제8권4A호
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• pp.482-489
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• 1999

AC PDP(P1asma Display Pane1)s use the mixture of inert gases to generate a discharge inside the display pixels. Impurities such as CO, $CO_2$ and OH inside discharge region may deteriorate the characteristics of PDP operation during long life time of PDP. Electro-negative gas such as CO can cause the sustain pulse amplitude to rise by attaching electrons which will play an important role in the earlier stage of the discharge. MgO film is used to protect the dielectric layer in AC PDP, and is in contact with the free space of display pixel where it is filled with the inert gas mixture. So, MgO film can be a main source of impurities. In this experiment, we observed the change of impurity generation of various MgO films which were deposited by different methods, by using QMS. (quadropole mass spectrometer) The main impurites were $H_2$, CO and $CO_2$. And with the comparison of the TPD (temperature programmed desorption) result, it can be understood that impurity gases are generated by sputtering of MgO surface not by outgassing. Deposition method had effects on the characteristics of the impurity generation. The MgO film manufactured by e-beam evaporation generated more amount of impurity gases than the MgO films manufactured by sputtering or ion-plating. And also heat treatment of MgO film after deposition decreased the magnitude of impurity gas generation.

• Plant Biotechnology Reports
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• 제2권2호
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• pp.113-122
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• 2008

Nitric oxide (NO) affects the growth and development of plants and also affects plant responses to various stresses. Because NO induces root differentiation, we examined whether or not it is involved in increased ROS generation. Treatments with sodium nitroprusside (SNP), an NO donor, 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (PTIO), a specific NO scavenger, and $N{\omega}-nitro-{\text\tiny{L}}-arginine$ methyl ester hydrochloride (${\text\tiny{L}}-NAME$), an NO synthase (NOS) inhibitor, revealed that NO is involved in the adventitious root growth of mountain ginseng. Supply of an NO donor, SNP, activates NADPH oxidase activity, resulting in increased generation of $O_2{^{{\cdot}-}}$, which subsequently induces growth of adventitious roots. Moreover, treatment with diphenyliodonium chloride (DPI), an NADPH oxidase inhibitor, individually or with SNP, inhibited root growth, NADPH oxidase activity, and $O_2{^{{\cdot}-}}$ anion generation. Supply of the NO donor, SNP, did not induce any notable isoforms of enzymes; it did, however, increase the activity of pre-existing bands of NADPH oxidase, superoxide dismutase, catalase, peroxidase, ascorbate peroxidase, and glutathione reductase. Enhanced activity of antioxidant enzymes induced by SNP supply seems to be responsible for a low level of $H_2O_2$ in the adventitious roots of mountain ginseng. It was therefore concluded that NO-induced generation of $O_2{^{{\cdot}-}}$ by NADPH oxidase seems to have a role in adventitious root growth of mountain ginseng. The possible mechanism of NO involvement in $O_2{^{{\cdot}-}}$ generation through NADPH oxidase and subsequent root growth is discussed.

• 한국환경과학회지
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• 제29권10호
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• pp.943-949
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• 2020

In this work, we prepared a heterojunction anode with a surface layer of SnO₂-Sb-Ni (SSN) on a Ti/IrO₂ electrode by thermal decomposition to improve the electrochemical activity of the Ti/IrO₂ electrode. The Ti/IrO₂-SSN electrode showed significantly improved electrochemical activity compared with Ti/IrO₂. For the 0.1 M NaCl and 0.1 M Na₂SO₄ electrolytes, the onset potential of the Ti/IrO₂-SSN electrode shifted in the positive direction by 0.1 V_SCE and 0.4 V_SCE, respectively. In 2.0-2.5 V voltages, the concentration in Ti/IrO₂-SSN was 2.59-214.6 mg/L Cl₂, and Ti/IrO₂ was 0.55-49.21 mg/L Cl₂. Moreover, the generation of the reactive chlorine species and degradation of Eosin-Y increased by 3.79-7.60 times and 1.06-2.15 times compared with that of Ti/IrO₂. Among these voltages, the generation of the reactive chlorine species and degradation of Eosin-Y were the most improved at 2.25 V. Accordingly, in the Ti/IrO₂-SSN electrode, it can be assumed that the competitive reaction between chlorine ion oxidation and water oxidation is minimized at an applied voltage of 2.25V.

• 한국광학회지
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• 제4권1호
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• pp.84-89
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• 1993

Mg(4 mole%):LiNb$O_3$에서 제 2고조파발생특성을 온도와 직류전장의 함수로 측정하여, Mg:LiNb$O_3$ 결정의 공간적 균일성을 조사 하였다. 발생된 제2고조파및의 세기가 위상정합된 상태의 최대값으로부터 최초로 0이 되는 온도가 결정의 광축으로 가해준 직류전장의 변화에 선형적으로 변위함을 관찰하였다. 이로부터, 최초로 Mg가 4mole% 첨가된 Mg:LiNb$O_3$ 의 전기광계수가 Congruent LiNb$O_3$의 해당하는 값보다 1.5배가 더 큼을 알 수 있었다.