• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.6
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• pp.467-471
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• 2000

The thermal annealing effect of $Zn_{0.9}Cd_{0.1}$ single quantum-well structures grown by molecular beam epitaxy is investigated. As the results of before and after rapid thermal annealed samples a red shift of E1-HH1 peak by Cd interdiffusion during thermal annealing of ZnCeSe/ZnSe sample was observed. In the case of annealed sample over $450^{\circ}C$ donor and acceptor impurities related peaks were observed which seems to be due to a diffusion of Ga and As from GaAs substrate. And also interdiffusion phenomena is idenified by the results of DCX measurements and which are consisten with the PL measurements.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.54 no.6
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• pp.293-297
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• 2005

Linearity is an important property of optical devices for analog communications. In this paper, we study the 3rd-order interrnodulation distortion (IMD3) of an Inp/InGaAsP multiple-quantum-well (MQW) traveling-wave type electroabsorption modulator (TW-EAM). We observe abnormal notches in the IMD3 results those were different from notches by general transfer curve of electroabsorption modulators (EAMs). We analyze the phenomena through absorption coefficients according to wavelengths and bias voltages to verify appearance of the abnormal notchs, where it can be known to result from Stark-shift and broadening. We propose the method to enhance linearity of MQW-EAMs by using these effects.

• Journal of Radiopharmaceuticals and Molecular Probes
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• v.8 no.1
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• pp.9-15
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• 2022

Anti-cancer and therapeutic effects using therapeutic radioisotopes have been demonstrated by various studies, and it is well-known that therapeutic radioisotopes are useful in cancer treatment. Recently, one of the therapeutic radioisotopes, scandium is emerging as a radioisotope applicable to PET imaging (⁴³Sc, ⁴⁴Sc) and therapy (⁴⁷Sc) in cancer theranostic approach. However, ⁴⁷Sc has little known radiobiological and therapeutic efficacy compared to other therapeutic radioisotopes. Here, we investigated the quality and therapeutic efficacy of ⁴⁷Sc radioisotope produced by our production/isolation technology at the research reactor 'HANARO' in KAERI (Korea Atomic Energy Research Institute). We showed that the therapeutic efficacy of ⁴⁷Sc, produced by our production/isolation technology, effectively suppressed epidermal growth factor receptor (EGFR)-targeted non-small cell lung cancer (NSCLC) cells. Consequently, these results suggest that the high quality of the produced ⁴⁷Sc by our production/isolation technology enables the development of therapeutic strategies for cancer treatment and radiopharmaceuticals using ⁴⁷Sc.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.7
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• pp.185-197
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• 1996

We have adopted the strain compensated PBH(planar buried heterostructure) - LD in which the MQW active layer consisted of 1.4% compressively strained GainAsP (E$_{g}$ = 0.905eV) wells and 0.7% tensile strained GaInAsP(E$_{g}$ = 1.107eV) barriers grown by metal organic vapor phase epitaxy (MOVPE). We hav einvestigated effects of number of wells and the structure of the separate confinement heterostructure (SCH) layer in the strain-compensated MQW-PBH-LD. The threshold current, the external quantum efficiency, the transparency current density J$_{o}$, and the gain constant .beta. have been evaluated for uncoated MQW-PBH-LD. As the number of wells increases, the internal quantum efficiency and the transparency current density decreases, whereas the gain contant increases. The small width of the SCH layer shows the large internal quantum efficiency. The small internal loss and the large gain constant have been obtained by inserting the large bandgap SCH layer.

• Korean Journal of Materials Research
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• v.31 no.8
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• pp.465-470
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• 2021

Deuterium is a crucial clean energy source required for nuclear fusion and is a future resource needed in various industries and scientific fields. However, it is not easy to enrich deuterium because the proportion of deuterium in the hydrogen mixture is scarce, at approximately 0.016 %. Furthermore, the physical and chemical properties of the hydrogen mixture and deuterium are very similar. Therefore, the efficient separation of deuterium from hydrogen mixtures is often a significant challenge when using modern separation technologies. Recently, to effectively separate deuterium, studies utilizing the 'Kinetic Quantum Sieving Effect (KQS)' of porous materials are increasing. Therefore, in this review, two different strategies have been discussed for improving KQS efficiency for hydrogen isotope separation performance using nanoporous materials. One is the gating effect, which precisely controls the aperture locally by adjusting the temperature and pressure. The second is the breathing phenomenon, utilizing the volume change of the structure from closed system to open system. It has been reported that efficient hydrogen isotope separation is possible using these two methods, and each of these effects is described in detail in this review. In addition, a specific-isotope responsive system (e.g., 2nd breathing effect in MIL-53) has recently been discovered and is described here as well.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.1
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• pp.49-58
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• 1998

In this paper, a new equivalent circuit model for quantum-well laser diode (LD) is proposed. The model includes carrier transport effects in the SCH region, and rprovides, in a stable and accurate manner, large-and small-signal responses of laser diode output power as function of injected currents. SPICE simulation was performed using the circuit model and results are presented for L-I characteristics, pulse and frequency responses under various conditions. It is expencted that the new equaivalent circuit model will find useful applications for designing and analyzing OEIC, LD driver circuits, and LD packaging.

• Korean Journal of Culture and Social Issue
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• v.11 no.spc
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• pp.85-95
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• 2005

The present article explored the studies on the relational mechanisms between trust and health in terms of psychosomatic medicine or integrative medicine. For this, the research findings of the Quantum physics, psychosomatic medicine, and traditional eastern healing methods on the mind-body problem and then a practical guide to greater physical and mental well-being is presented. In the first section of the Quantum mechanical human body, the body has a mind of its own, the mechanism and cause of disease, the body as objective experienced conscious, and the effects of consciousness and information on the body are includes. The second section is psychosomatic medicine. In this, the thought changing brain, placebo, the power of expectancy, achieving health by active endeavor, psychoneuroimmunology, and the several therapies are included. Finally, Dr. Benson and Proctor's practical guide to well-being in presented. It is emphasized that the four trusts (trust in oneself, one's doctor, one's treatment, and one's spiritual trust) are crucial to recovery from serious illness and to achieve better health.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.65-65
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• 2015

In this talk, I will introduce two topics. The first topic is the polymer light emitting diodes (PLEDs) using graphene oxide quantum dots as emissive center. More specifically, the energy transfer mechanism as well as the origin of white electroluminescence in the PLED were investigated. The second topic is the facile synthesis of eco-friendly III-V colloidal quantum dots and their application to light emitting diodes. Polymer (organic) light emitting diodes (PLEDs) using quantum dots (QDs) as emissive materials have received much attention as promising components for next-generation displays. Despite their outstanding properties, toxic and hazardous nature of QDs is a serious impediment to their use in future eco-friendly opto-electronic device applications. Owing to the desires to develop new types of nanomaterial without health and environmental effects but with strong opto-electrical properties similar to QDs, graphene quantum dots (GQDs) have attracted great interest as promising luminophores. However, the origin of electroluminescence (EL) from GQDs incorporated PLEDs is unclear. Herein, we synthesized graphene oxide quantum dots (GOQDs) using a modified hydrothermal deoxidization method and characterized the PLED performance using GOQDs blended poly(N-vinyl carbazole) (PVK) as emissive layer. Simple device structure was used to reveal the origin of EL by excluding the contribution of and contamination from other layers. The energy transfer and interaction between the PVK host and GOQDs guest were investigated using steady-state PL, time-correlated single photon counting (TCSPC) and density functional theory (DFT) calculations. Experiments revealed that white EL emission from the PLED originated from the hybridized GOQD-PVK complex emission with the contributions from the individual GOQDs and PVK emissions. (Sci Rep., 5, 11032, 2015). New III-V colloidal quantum dots (CQDs) were synthesized using the hot-injection method and the QD-light emitting diodes (QLEDs) using these CQDs as emissive layer were demonstrated for the first time. The band gaps of the III-V CQDs were varied by varying the metal fraction and by particle size control. The X-ray absorption fine structure (XAFS) results show that the crystal states of the III-V CQDs consist of multi-phase states; multi-peak photoluminescence (PL) resulted from these multi-phase states. Inverted structured QLED shows green EL emission and a maximum luminance of ~45 cd/m2. This result shows that III-V CQDs can be a good substitute for conventional cadmium-containing CQDs in various opto-electronic applications, e.g., eco-friendly displays. (Un-published results).

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.1
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• pp.11-16
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• 2014

The effects of environment and microstructure on low cycle fatigue (LCF) behaviors of CF8M stainless steels containing 11% of ferrites were investigated in a $310^{\circ}C$ deoxygenated water environment. The reduction of LCF life of CF8M in a $310^{\circ}C$ deoxygenated water was smaller than 316LN stainless steels. Based on the microstructure and fatigue surface analyses, it was confirmed that the hydrogen induced cracking contributed to the reduction in LCF life for CF8M as well as for 316LN. However, many secondary cracks were found on the boundaries of ferrite phases in CF8M, which effectively reduced the stress concentration at the crack tip. Because of the reduced stress concentration, the accelerated fatigue crack growth by hydrogen induced cracking was less significant, which resulted in the smaller environmental effects for CF8M than 316LN in a $310^{\circ}C$ deoxygenated water.

• Journal of the Korean Vacuum Society
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• v.18 no.1
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• pp.37-43
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• 2009

Temperature and injection current dependence of electroluminescence(EL) spectral intensity of the $In_xGa_{1-x}N$/GaN multi-quantum wells(MQW) have been studied over a wide temperature range and as a function of injection current level. It is found that a temperature-dependent variation pattern of the EL efficiency under very low and high injection currents shows a drastic difference. This unique EL efficiency variation pattern with temperature and current can be explained field effects due to the driving forward bias in presence of internal(piezo and spontaneous polarization) fields. Increase of the indium content in $In_xGa_{1-x}N$/GaN multiple quantum wells gives rise to a redshift of 80 meV and 22 meV for green and blue MQW, respectively. It can be explained by carrier localization by potential fluctuation of multiple quantum well and MQW structures also shows a keen difference owing to the different indium content in InGaN/GaN MQW.