• Title/Summary/Keyword: quantum well

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Taekyo as Mind and Body Science (심신과학으로서의 태교)

  • Lee, Kyung-Hye;Bae, Kyung-Eui
    • Korean Parent-Child Health Journal
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    • v.7 no.1
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    • pp.61-72
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    • 2004
  • This study investigates the history and principles of Korean traditional Taekyo by literary research. Taekyo is compared with prenatal care of modern western medicine, and its principles turn out to be just as scientific. Suggestions are made for a nurse to apply Taekyo principles to nursing care. Traditional Taekyo is an antenatal training which emphasizes how an expectant mother should carry herself (behavior) and a frame of mind she should have (her attitude) in order to produce a child with sound mind and body, as well as good personality. Though Taekyo has been originated in China 2,800 years ago, it has been recorded comprehensively in Korea in a series of publications such as Taekyoshingi, and Kyuhapchongseo, and passed on in a various verbal transitions like Samtaedo, Oliltaedo, etc. Taekyo principles can be explained by yin and yang theory, quantum theory, chaos theory, fetal programming, and social support theory. Some part of Taekyo shares the same scientific ground with prenatal care advocated by modern nursing care for women, where it emphasizes the role of a father, and participation of the whole family in helping an expectant mother. Applying Taekyo principles to nursing care is being done through Taekyo programs, which combine traditional Taekyo with modern prenatal care, in classes for child birth and many pregnant women participate. On the other hand, some internet Taekyo programs appear to be rather distorted and overzealous. A nurse has a responsibility to present a guideline and to monitor internet sites, so that pregnant women can understand the correct concept of traditional Taekyo before they practice it.

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Effect of carrier concentration of ITO films on Quantum Efficiency Window in Heterojunction Silicon Solar Cells

  • Kim, Hyunsung;Kim, Sangho;Yi, Junsin
    • Proceedings of the Korean Vacuum Society Conference
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    • 2016.02a
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    • pp.314-314
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    • 2016
  • In this paper, the effects of carrier concentration on dielectric constant of ITO films were investigated by spectroscopic ellipsometry. From SE results, we find the pronounced shift of the ${\varepsilon}1$ peaks toward high energy with concentration; while contrarily, the ${\varepsilon}2$ values at low energy region increases with decreasing concentration. These shifts are attributed to the Burstein-Moss and free-carrier absorption effects within ITO films. With increases carrier concentration, the values of extinction coefficients show quite different behaviors in range of wavelength from 200 to 1200 nm. The reduction in k at ${\lambda}{\leq}500nm$, while increasing at ${\lambda}{\geq}500nm$ was observed. The QE of HJ solar cells behaviors can be roughly classified into two regions: short-wavelengths (${\leq}650nm$) and long-wavelengths region (${\geq}650nm$). With increasing carrier concentration as well as energy band gap, QE shows improvement at short-wavelength, while at long-wavelength QE shows opposite trend. Widening band gap energy due to Burstein-Moss shift is the key to improve QE in short-wavelength; simultaneously FCA effect due to optical scattering is attributed to the reduction in QE at long-wavelength. In spite of band gap extension, Jsc calculated from QE decreases from 34.7 mA/cm2 to 33.2 mA/cm2 with increasing carrier concentration. It demonstrated that FCA effect may more govern Jsc in the HJ solar cells.

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Assessment of Heavy Metal Effects on the Freshwater Microalga, Chlorella vulgaris, by Chlorophyll Fluorescence Analysis (엽록소형광분석을 이용한 담수산 클로렐라(Chlorella vulgaris)에 미치는 중금속의 영향 평가)

  • Oh, Soon-Ja;Koh, Seok-Chan
    • Journal of Environmental Science International
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    • v.24 no.12
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    • pp.1591-1600
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    • 2015
  • The response of the freshwater microalga, Chlorella vulgaris, to heavy metal stress was examined based on chlorophyll fluorescence analysis to assess the toxic effects of heavy metals in freshwater ecosystems. When toxic effects were analyzed using regular chlorophyll fluorescence analysis, photosystem II activity($F_v/F_m$) decreased significantly when exposed to $Cu^{2+}$ and $Hg^{2+}$ for 12 h, and decreased in the order of $Hg^{2+}>Cu^{2+}>Cd^{2+}>Ni^{2+}$ when exposed for 24h. The effective photochemical quantum yield(${\phi}{\prime}_{PSII}$), chlorophyll fluorescence decrease ratio($R_{Fd}$), minimal fluorescence yield($F_o$), and non-photochemical quenching(NPQ), but not photochemical quenching(qP), responded sensitively to $Hg^{2+}$, $Cu^{2+}$, and $Cd^{2+}$. These results suggest that $F_v/F_m$, as well as ${\phi}{\prime}_{PSII}$, $R_{Fd}$, $F_o$, and NPQ could be used to assess the effects of heavy metal ions in freshwater ecosystems. However, because many types of heavy metal ions and toxic compounds co-occur under natural conditions, it is difficult to assess heavy metal toxicity in freshwater ecosystems. When Chlorella was exposed to heavy metal ions for 12 or 24h, $F_v/F_m$ and maximal fluorescence yield($F_m$) changed in response to $Hg^{2+}$ and $Cu^{2+}$ based on image analysis. However, assessing quantitatively the toxic effects of several heavy metal ions is challenging.

Silicon wire array fabrication for energy device (실리콘 와이어 어레이 및 에너지 소자 응용)

  • Kim, Jae-Hyun;Baek, Seung-Ho;Kim, Kang-Pil;Woo, Sung-Ho;Lyu, Hong-Kun
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2009.06a
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    • pp.440-440
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    • 2009
  • Semiconductor nanowires offer exciting possibilities as components of solar cells and have already found applications as active elements in organic, dye-sensitized, quantum-dot sensitized, liquid-junction, and inorganic solid-state devices. Among many semiconductors, silicon is by far the dominant material used for worldwide photovoltaic energy conversion and solar cell manufacture. For silicon wire to be used for solar device, well aligned wire arrays need to be fabricated vertically or horizontally. Macroscopic silicon wire arrays suitable for photovoltaic applications have been commonly grown by the vapor-liquid-solid (VLS) process using metal catalysts such as Au, Ni, Pt, Cu. In the case, the impurity issues inside wire originated from metal catalyst are inevitable, leading to lowering the efficiency of solar cell. To escape from the problem, the wires of purity of wafer are the best for high efficiency of photovoltaic device. The fabrication of wire arrays by the electrochemical etching of silicon wafer with photolithography can solve the contamination of metal catalyst. In this presentation, we introduce silicon wire arrays by electrochemical etching method and then fabrication methods of radial p-n junction wire array solar cell and the various merits compared with conventional silicon solar cells.

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The Effect of Laser Geometry and Material Parameters on the Single Mode Gain Difference in Quarter Wavelength Shifted DFB Laser above Threshold Current (문턱전류이상에서 구조 및 재료 변수들이 $\lambda$/4위상천이 DFB 레이저의 단일모드 이득차에 미치는 영향)

  • 이홍석;김홍국;김부균;이병호
    • Journal of the Korean Institute of Telematics and Electronics D
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    • v.36D no.3
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    • pp.75-84
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    • 1999
  • Systematic studies for the effect of the linewidth enhancement factor, the confinement factor, the internal loss and the cavity length on the single mode gain difference and the frequency detuning are performed for $\lambda$/4 phase shifted DFB lasers above threshold. The above threshold characteristics are mainly determined by the linewidth enhancement factor, not by the confinement factor or the parameter defined by the product of the linewidth enhancement factor and the confinement factor. The normalized internal loss defined by the product of the internal loss and the cavity length mainly determines the above threshold characteristics compared to that of the internal loss or the cavity length alone. The effect of the cavity length on threshold characteristics is larger than that of the internal loss in the case of the same normalized internal loss. The above threshold characteristics of quantum well lasers are more resistant to the variations of the confinement factor and the normalized internal loss than those of bulk lasers due to the small linewidth enhancement factor.

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Synthesis of scheelite-type nanocolloidal particles by pulsed laser ablation in liquid and their size distribution analysis

  • Lee, Jung-Il;Shim, Kwang Bo;Ryu, Jeong Ho
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.24 no.3
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    • pp.111-119
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    • 2014
  • A novel pulsed laser ablation process in liquid was investigated to prepare scheelite-type ceramic [calcium tungstate ($CaWO_4$) and calcium molybdate ($CaMoO_4$)] nanocolloidal particles. The crystalline phase, particle morphology, particle size distribution, absorbance and optical band-gap were investigated. Stable colloidal suspensions consisting of well-dispersed $CaWO_4$ and $CaMoO_4$ nanoparticles with narrow size distribution could be obtained without any surfactant. Particle tracking analysis using optical microscope combined with image analysis was applied for a fast determination of particle size distribution in the prepared nanocolloidal suspensions. The mean nanoparticle size of $CaWO_4$ and $CaMoO_4$ colloidal nanoparticles were 16 nm and 30 nm, with the standard deviations of 2.1 and 5.2 nm, respectively. The optical absorption edges showed blue-shifted values about 60~70 nm than those of reported in bulk crystals. And also, the estimated optical energy band-gaps of $CaWO_4$ and $CaMoO_4$ colloidal particles were 5.2 and 4.7 eV. The observed band-gap widening and blue-shift of the optical absorbance could be ascribed to the quantum confinement effect due to the very small size of the $CaWO_4$ and $CaMoO_4$ nanocolloidal particles prepared by pulsed laser ablation in liquid.

Electronic Properties and Conformation Analysis of π-Conjugated Distyryl Benzene Derivaties

  • Kim, Cheol-Ju
    • Bulletin of the Korean Chemical Society
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    • v.23 no.2
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    • pp.330-336
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    • 2002
  • A quantum-chemical investigation on the conformations and electronic properties of bis[2-{2-methoxy-4,6-di(t-butyl)phenyl}ethenyl]benzenes (MBPBs) as building block for ${\pi}$-conjugate polymer are performed in order to display the effects of t-butyl and methoxy group substitution and of kink(ortho and meta) linkage. The conjugation length of the polymers can be controlled by substituents and kink linkages of backbone. Structures for the molecules, o-, m-, and p-MBPBs as well as unsubstituted o-, m-, and p-DSBs were fully optimized by using semiempirical AM1, PM3 methods, and ab initio HF method with 3-21G(d) basis set. The potential energy curves with respect to the change of single torsion angle are obtained by using semiempirical methods and ab initio HF/3-21G(d) basis set. The curves are similar shape in the molecules with respect to the position of vinylene groups. It is shown that the conformations of the molecules are compromised between the steric repulsion interaction and the degree of the conjugation. Electronic properties of the molecules were obtained by applying the optimized structures and geometries to the ZINDO/S method. ZINDO/S analysis performed on the geometries obtained by AM1 method and HF/3-21G(d) level is reported. The absorption wavelength on the geometries obtained by AM1 method is much longer than that by HF/3-21G(d) level. The absorption wavelength of MBPBs are red shifted with comparison to that of corresponding DSBs in the same torsion angle because of electron donating substituents. The absorption wavelength of isomers with kink(orth and meta) linkage is shorter than that of para linkage.

The basic study on the origin of recently emerging Meridian-based Psychotherapy (최근 등장한 경락기반 심리치료법의 연원에 대한 기초 연구)

  • Lee, Jeong-Won;Kim, Gyeong-Cheol
    • Korean Journal of Oriental Medicine
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    • v.18 no.2
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    • pp.123-130
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    • 2012
  • Objectives : The purpose of this study is to identify the origin of meridian-based psychotherapy, and thereby utilize this technique more flexibly and widely, as well as use our findings as the base data for the development of unique and oriental medicine-based psychotherapies. Methods : This study investigated various activities and references of meridian-based psychotherapy developers in historical order. For the books that have been translated into Korean, the translated books were examined as priority. Otherwise, examination was based on original books. Results : The study results were as follows. EFT (Emotional Freedom Techniques) is a technique completed by combining the psychological reversal, acupuncture point tapping, and gamut series in TFT (Thought Field Therapy), and the affirmations that were formed by reflecting the deep understanding on languages derived from NLP (Neuro Linguistic Programming). ESM (Emotional Self Management) can be viewed as having applied the implications of cognitive therapy and hypnosis while accepting the treatment of TFT as it is. Roger J. Callahan developed TFT by adopting theories such as AK(Applied Kinesiology), acupuncture, NLP, quantum mechanics, and split brains. On the EFT, ESM, TFT, the method for stimulating acupuncture points appears to be tapping, which is one technique of the oriental traditional exercise and manual techniques(導引按蹻). Tapping may be the English translation of Bak-beop(拍法). Conclusions : When the oriental medicine techniques that enable meridian tuning are applied along with accommodating Western psychological theories actively, this can not only help use meridian-based psychotherapy more flexibly, but also enable the development of new oriental medicine-based psychotherapies.

Recent Advances in Di-$\pi$-methane Processes. Novel Reactions of 1,4-Unsaturated Compounds Promoted by Triplet Sensitization and Photoelectron Transfer

  • Armesto, Diego;Ortiz, Maria J.;Agarrabeitia, Antonia R.
    • Journal of Photoscience
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    • v.10 no.1
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    • pp.9-20
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    • 2003
  • Recent studies on the photoreactivity of l,4-unsaturated systems have changed some ideas that were firmly established in this area of research for many years. Thus, we have described the first examples of 2-aza-di-$\pi$-methane (2-ADPM) rearrangements promoted by triplet-sensitization and by single electron transfer (SET) using electron-acceptor sensitizers. These reactions afford N-vinylaziridine and cyclopropylimine photoproducts in the first examples of di-$\pi$-methane processes that yield three-membered ring heterocycles. l-Aza-1,4-dienes also undergo SET-promoted l-aza-di-$\pi$-methane (l-ADPM) rearrangements via radical-cation intermediates using electron acceptor sensitizers. In some cases, alternative cyclizations yielding different carbocycles and heterocycles have been observed. The l-ADPM and di-$\pi$-methane (DPM) reactions also occur via radical-anion intermediates on irradiation using electron donor sensitizers. On the other hand, the photoreactivity reported for $\beta$,${\gamma}$-unsaturated aldehydes for many years was decarbonylation to the corresponding alkenes. However, our studies demonstrate that these compounds undergo the oxa-di-$\pi$-methane (ODPM) rearrangement with high chemical and quantum efficiency. A comparison of the photochemical reactivity of $\beta$,${\gamma}$-unsaturated aldehydes and corresponding methyl ketones has shown that the ketones do not undergo the ODPM rearrangement while the corresponding aldehydes are reactive by this pathway. Monosubstituted $\beta$,${\gamma}$-unsaturated aldehydes at C-2 undergo the ODPM rearrangement yielding the corresponding cyclopropane carbaldehydes diastereoselectively. Finally, we have described the first examples of reactions, similar to the well know Norrish Type I process, which take place in the triplet excited state of $\beta$,${\gamma}$-unsaturated carbonyl compounds by excitation of the C-C double bond instead of the carbonyl group.

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SPICE Simulation of All-Optical Transmitter/Receiver Circuits Configured with MQW Optical Modulators and FETs (다층 양자우물구조 광 변조기와 전계효과 트랜지스터를 사용한 광 송/수신기회로의 SPICE 모사)

  • 이유종
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 1999.05a
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    • pp.420-424
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    • 1999
  • In this paper, an optical switching circuit and several types of all-optical transmitter/receiver circuits which are configured with photodiodes, multiple quantum-well(MQW) optical modulators, and field-effect transistors(FETs) were simulated using PSPICE and their results of these are examined and discussed. 20 $\mu\textrm{m}$ ${\times}$ 20 $\mu\textrm{m}$ of window size was used for the optical modulators and 100 $\mu\textrm{m}$ wide FETs with the transconductance value of 55 mS/mm were used for the simulations. Simulation results clearly show that in order for the high speed operation of the all-optical circuits, the size of each device should be minimized to reduce the parasitic capacitance, the circuits should be designed to operate at the wavelength where the resposivity of photodiodes becomes the maximum peak, and the use of short, high-intensity input optical signal beams is very advantageous.

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