• Proceedings of the Korea Association of Crystal Growth Conference
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• 1999.06a
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• pp.227-250
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• 1999

The reproducibility of successive growth of Bi12TiO20(BTO) single crystals using a top-seeded solution growth (TSSG) pulling method was evaluated by measuring the lattice constants and their standard deviations. A substantial phase diagram in the region close to the stoichiometric BTO was established experimentally for this purpose, and the existence of a retrograde solid solution close to a BTO was clarified. It was emphasize that a starting solution, with a 10.0~10.1 mol% TiO2 concentration, results in large single crystals with a highly homogeneous lattice constant of within $\pm$1x10-4$\AA$, when the solidified fraction of the grown crystal is less than about 45%. A wavelength dispersion of refractive index was measured for the first time, an it was verified that the refractive index of BTO is larger than that of BSO(Bi12TiO20), allowing the voltage sensitivity of EOS higher than the case with BSO as a probe head.

• Journal of the Korean institute of surface engineering
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• v.52 no.1
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• pp.6-15
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• 2019

Metal-halide perovskite (MHP) solar cell is a promising candidate for next-generation flexible devices and the BIPV (Building-integrated photovoltaics) because it can exhibit high power conversion efficiencies over 23%, good bendability and low processing cost. However, MHP solar cells are commonly fabricated by the spin coating that is not a reliable method to produce large-scale commercial solar cells. A shear coating can be one of the potential candidates for the large-scale deposition method of MHP films. In this work, the influences of the process parameters such as solvents of precursor solution, substrate temperature, concentrations of precursor solution, and annealing time on the thin film growth of MHP were investigated for the shear coating process. This study presents the possibility of the shear coating process for large-scaled perovskite film fabrication and reveals the role of process condition in the thin film growth of perovskites.

• Medical Lasers
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• v.10 no.3
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• pp.176-180
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• 2021

Several methods have been used to treat androgenetic hair loss, ranging from hair transplants to finasteride and minoxidil. Sometimes platelet-rich plasma injection therapy may be used to increase the satisfaction of patients who come to the hospital. However, some patients are sensitive to pain and are subjected to the inconvenience of requiring treatment after each blood sampling. The author had reported the effects of using a hair growth-promoting solution and Jetpeel^TM in parallel with a painless hair loss treatment method. However, the author was interested in more effective methods for patients with M-shaped or vertex hair loss who do not want to take medications or undergo hair transplant. In addition to the existing light-emitting diode therapy and electromagnetic field treatment, the author has made considered attempts to use various laser wavelength bands. However, the equipment for these methods can be expensive and are not suitable for patients who emphasize on cost-effectiveness. Therefore, the author used an existing reported method and a device based on the fractional erbium:YAG laser to provide the hair growth-promoting solution in parallel. The author chose a fractional 2940 nm-based laser device as a medium that could efficiently increase the growth phase, reduce the catagen phase, and facilitate intradermal product and drug delivery. As a result, there was a therapeutic benefit without any significant side effects such as redness and itching. Among the patients, the author reported the effects of the treatment on one patient with frontal M-shaped, mid, and vertex hair loss.

• Economic and Environmental Geology
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• v.24 no.3
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• pp.219-226
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• 1991

High quality quartz crystals are grown in 0.5N NaOH + LiOH solution on the seed crystal at $370-395^{\circ}C$ and $1200-1300kg/cm^2$ condition. Growth rates are determined by the crystal thickness grown on the seed crystals with Z(0001) and X($11\bar{2}0$) direction. Relatively high growth rate of Z(0001) direction gradually changes as the temperaure difference (${\Delta}$ Ti) between growth and dissolution zones from 25 to $10^{\circ}C$. The X axis direction is affeced by ${\Delta}$ Ti, and +X($11\bar{2}0$) direction shows a high growth rate than -X($\bar{1}\bar{1}20$) direction. According to the variation with kinds of solutions used, the crystal growth that in NaOH solution is found to be slower than that in $Na_2CO_3$ solution. However, for the case in the NaOH solution mixed with LiOH, it shows a favorable growth rate in terms of grown crystal quality.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.16 no.1
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• pp.1-7
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• 2006

Some lead-based crystals show excellent ferroelectric, piezoelectric or scintillation properties and have attracted much attention in recent years. However, the erosion of the high temperature solution on platinum crucible and the evaporation of PbO component are the main problems often encountered during the crystal growth. In this paper, we reported recent progress on the Bridgman growth of lead-based functional crystals, such as novel relaxor ferroelectric crystals (PZNT and PMNT), scintillation crystals $(PbWO_4,\;PbF_2\;and\;PbClF)$ and piezoelectric crystals $(Pb_5Ge_3O_{11}\;and\;Pb_2KNb_5O_{15}),$ in Shanghai Institute of Ceramics, Chinese Academy of Sciences. The vertical Bridgman method has been modified to grow PZNT crystals from high temperature solution and as-grown crystals have been characterized. Large size lead-based scintillators, $PbWO_4\;and\;PbF_2$ crystals, have been mass-produced by the vertical Bridgman method in the multi-crucible fumace. These crystals have been supplied to CERN and other laboratories for high-energy physics experiments. The Bridgman growth of piezoelectric crystals $Pb_5Ge_3O_{11}\;and\;Pb_2KNb_5O_{15}$ are discussed also.

• Journal of Advanced Marine Engineering and Technology
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• v.26 no.2
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• pp.240-247
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• 2002

Recently, a thermal energy storage system has been developed actively fur the purpose of saving energy and reducing the peak electrical demand. Especially, ice slurry is a promising working fluid for low temperature energy storage systems. A flow of ice crystals has a large cooling capacity as a result of the involvement of latent heat. However, there are still problems related to the recrystallization of ice crystals for realizing long term storage and long distance transportation. To find improvements fur this, a method for the creation of ice crystals resistant to recrystallization has been proposed and researched by the use of an antifreeze protein (AFP) solution etc. In the present study, it has been investigated the growth of ice crystal in several kinds of water solution added non-ionic surfactant. The results shows that size of ice crystal was smaller with increasing in added surfactant. And ice crystal was not increased with added surfactant.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.9 no.4
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• pp.424-431
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• 1999

The reproducibility of successive growth of $Bi_{12}TiO_{20}$ (BTO) single crystlas using a top-seeded solution growth (TSSG) pulling method was evalutated by measuring the lattice constants and their standard deviations. A substantial phase diagram in the region close to the stoichiometric BTO was established expermentally for this purpose, and the existence of a retrograde solid solution close to a BTO was clarified. It was emphasized that a starting solution, with a 10.0~10.1 mol% $TiO_{2}$ concentration, results in large single crystals with a highly homogeneous lattice constant of within ${\pm}1{\times}10^{-4}\AA$, when the solidified fraction of the grown crystal is less than about 45 %. A wavelength dispersion of refractive index was measrued for the first time, and it was verified that the refractive index of BTO is larger than that of BSO($Bi_{12}TiO_{20}$), allowing the voltage sensitivity of EOS higher than the case with BSO as a probe head.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.5
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• pp.772-778
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• 2001

In this study, corrosion fatigue characteristics of 12Cr alloy steel were investigated in 3.5wt.% NaCl solution of 150$^{\circ}C$ and 4.5bar. Behavior of corrosion fatigue cracks was measured by the indirect compliance method and compared with the results in distilled water and in air. 1) 12Cr alloy steel was susceptible to temperature. Its susceptibility was increased as the temperature was increased. 2) The crack growth characteristics of 12Cr alloy steel in distilled water were similar to 3.5wt.% NaCl solution. 3) The temperature of solution affects to the crack growth characteristics of 12Cr alloy steel. In corrosion solutions of 4.5bar, 150$^{\circ}C$, fracture surfaces of corrosion fatigue crack growth at a/W=0.3 was showed the trans-granular fracture suface. As the crack grew up, it was changed to inter-granular type. In condition of high temperature, The crack growth behaviors of 12Cr alloy steel were remarkable.

• Proceedings of the Korea Association of Crystal Growth Conference
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• 1996.06a
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• pp.519-521
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• 1996

Emerald (3BeO.Al2O3.6SiO2 : Cr3+) single crystals were crystals were grown by reflux method of temperature gradient in the flux solution of Li2O-MoO3-V2O5 system. The composition of flux materials were 3 mole ratio of MoO3-V2O5/Li2O, subtituted 0.2 mole% of K2O, Na2O, Nb2O5 etc to Li2O content, solved 10-15% of beryl to flux quantity and doped 1% of Cr2O3 to emerald amount. Those of mixing were melted at 110$0^{\circ}C$ in Pt containers of the 3 zone furnace of melt-growth-return to circulate continniously, specially it has been grown large emerald single crystal when thermal fluctuation was treated for 2hrs of once time a day at 1050-95$0^{\circ}C$ in growth zone, substitutional solid solution effect of Cr+3 ion for Al+3 to the growth of emerald single crystal was good. Emerald single crystals were c(0001) hexagonal crystal face of preferencial growth direction and m(1010) post side. When it had been durated for 5 months emerald single crystals of the firet size of 0.6mm thickness of seed crystal were grown 32$\times$65mm(c x m) of maximum size and 6.2mm thickness.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.5 no.3
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• pp.223-232
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• 1995

Abstract Urea($(NH_2)_2CO$) and THAMP (Tris(hydroxymethyl) aminomethane phosphate) are new organic nonlinear optical materials (NLO) for the device application such as the frequency conversion of laser radiation. The single crystals of urea and THAMP have been grown by the falling temperature method and the temperature difference method. The crystal growth parameters were presented associated with the molphology of the grown crystals. Based on the solubility measurements, methanol was a suitable solvent for the growth of urea. The solubilities of urea have a positive temperature coefficient and the heat of solution of urea was estimated to be -2.58 kcal/mol. The grown crystals of urea have the preferential growth habit in the z-axis. Additives such as $NH_4_H_2PO_4$, KCL, $H_3PO_4$, $CaCl_2{\cdot}2H_2O$, $C_2H_5OH$ were used for the favourable growth in the x - and y-axis and the preventive growth in the z-axis. The moleratio of THAM and H3P04 for the solution of THAMP was 1 : 1. The solubilities of THAMP have a positive temperature coefficient. The heat of solution was estimated to be - 1.70 kcal/ mol.