• Journal of Applied Tourism Food and Beverage Management and Research
• /
• v.15 no.1
• /
• pp.113-125
• /
• 2004

Effect of microwave radiation on physico-chemical properties of cor'n starches was studied. Waxy com, com and high amylose com starches of varying moisture content(20～35%) were subjected to microwave processing(2450MHz) at $120^{\circ}$ and the experimental starch samples were examined by a X-ray diffractometry, rapid viscosity analyzer(RVA) and. with the samples in temperature was observed and the peaks of high amylose com starches at $2^{\circ}$=5.0, 15.0 and $23.0^{\circ}$, were disappeared indicating the melting of crystallines while those of com and waxy com had not changed. A change in gelatinization pattern was observed in the case of corn starches from type A with nearly no peak-viscosity and breakdown to type C. Except a decreased viscosity, no change was observed in those of waxy com starches.

• Korean Journal of Ichthyology
• /
• v.30 no.3
• /
• pp.161-166
• /
• 2018

The olfactory organ of Korean endemic fish Microphysogobio yaluensis are described anatomically and histologically, focused on relationship to its habitat and ecology. The paired olfactory organs are located at the dorsal snout, and externally consist of two semicircular nostrils and single nasal flap. They internally have rosette structure with 22 to 24 units of lamellae and the raphe inside the olfactory chamber. The lamella is made up of the sensory and the non-sensory epitheliums. The sensory epithelium has olfactory receptor neurons, supporting cells and basal cells whereas the nonsensory epithelium has stratified epithelial cells, ciliated non-sensory cells and mucous cells with acidic and neutral mucins. These structures might be considered that M. yaluensis has the olfactory organ which corresponds to the high sensitivity for its habitat and ecology, and is usable as a taxonomic key.

• Korean Chemical Engineering Research
• /
• v.44 no.4
• /
• pp.399-403
• /
• 2006

There has been numerous reports for the synthesis of mesoporous $TiO_2$ thin films due to not only the high surface area and regular mesoscale pores but also wide band gap and photo activity. However, the synthesis has been restricted by the limited reproducibility mainly due to the extraordinarily fast hydrolysis and condensation rate of titania precursors. In this report, molar composition of reaction batch (HCl/Ti and Ti/P123) and exterior condition (humidity and temperature) during coating and anealing process. Thereafter, the mesoporous $TiO_2$ thin films were characterized by XRD and TEM

• Polymer(Korea)
• /
• v.32 no.5
• /
• pp.478-482
• /
• 2008

The effect of 1,3-dioxolane on the structural development in the optical polycarbonate film was studied. The 1,3-dioxolane was used as an environmental friendly solvent for manufacturing solution-cast polycarbonate film instead of methylene chloride. The evaporation rate in film drying process decreased due to the high boiling temperature of 1,3-dioxolane. This caused the crystallization in the polycarbonate film. As a result, The increase of crystallinity and roughness led to the decrease of light transmissivity. It was also found that the lowering of mechanical properties in polycarbonate film was attributed to the morphological change due to the solvent evaporation rate in film drying process.

• Polymer(Korea)
• /
• v.29 no.3
• /
• pp.308-313
• /
• 2005

The effects of molecular environments on photoisomerization of an azobenzene group were investigated using In-situ UV/Vis spectroscopy and optical anisotropy measurement technique. The reversible and repeatable photoisomeritation reactions of azobenzene were observed by irradiating the film containing 4-hydroxyazobenzene and by measuring absorption intensities of the characteristic bands of trans and cis isomers simultaneously. When the self-assembled monolayer with azobenzene groups was used as an alignment layer for a liquid crystal cell, the homeotropic alignment was induced due to their compact packing structures of azobenfene groups along the vertical direction of the substrate. By irradiating UV light on this cell, the trans-azobenzene groups change to cis-isomers through the photoisonlerieation and then resulting in the planar alignment of liquid crystal molecules.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.37 no.7
• /
• pp.669-674
• /
• 2013

A three-dimensional hydrogel scaffold has been proposed for the effective production of biomimetic intestinal villi to reduce ethical and cost problems caused by animal testing in pharmaceutical development. This study explores an experimental approach to develop a new technique based on laser machining and microdrilling processes to produce a plastic mold for the fabrication of a three-dimensional hydrogel scaffold. For process optimization, both the laser machining and the microdrilling experiments are conducted by varying the experimental conditions, and structural characterization of the mold and intestinal villi were performed using SEM (scanning electron microscope) and OM (optical microscope) images. Polycarbonate (PC) was used as a candidate material. The experimental results show that intestinal villi can be fabricated by both laser and microdrilling machining processes.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.50 no.7
• /
• pp.455-463
• /
• 2022

As the need for R&D for high reliability cameras, such as satellite cameras, increases, the reliability of the bonding strength properties between an opto-mechanical structure and an optical component has been secured through specimen tests. However, the widely used specimen shape is not suitable for the application of glass and glass-ceramic material, which is fragile, making it difficult to obtain accurate bonding properties due to stress concentration in glass parts before reaching the bonding strength limit. In this study, the stress distribution characteristics in the shear test condition for various specimen shapes were studied analytically, based on the test results of the glass material's own fracture. Through this, the shape characteristics capable of relieving the stress concentration of the glass part were derived, and the range of the bonding shear strength verifiable by the specimen test was improved.

• Korean Journal of Ichthyology
• /
• v.34 no.3
• /
• pp.153-159
• /
• 2022

The olfactory organ of a Korean endemic species, Pseudobagrus koreanus, was investigated to describe its morphology and histology and analyze correlation between habitat environment and its ecological habits and characters, using a stereo microscope, a light microscope, and a scanning electron microscope. Its external morphology showed tubular anterior nostril at the tip of the snout and slit posterior nostril at the base of the nasal barbel. The olfactory chamber showed the rosette structure consisting of numerous lamellae radial and parallel to the medium raphe. The olfactory lamella has the sensory epithelium with olfactory receptor nuerons, supporting cells, basal cells, lymphatic cells, plasma cells and the non-sensory epithelium with stratified epithelial cells, mucous cells, lymphatic cells. In particular, 1) 41~43 (n=20) lamellae, 2) lymphatic cells and plasma cells, 3) mucous cells including neutral polysaccharid may be olfactory characteristics relevant to a stagnant or a standing habitat environment, nocturnal habit dependent on olfaction, and taxonomic characters compared at least to other catfish species.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.27 no.1
• /
• pp.42-46
• /
• 2017

$SrAl_2O_4$ : $Eu^{2+}$,$Dy^{3+}$ phosphorescent phosphors were synthesized by skull melting method. The molar ratio of oxides in the phosphors synthesized by the skull melting technique was $SrCO_3$ : $Al(OH)_3$ : $Eu_2O_3$ : $Dy_2O_3$= 1 : 2 : 0.015 : 0.02. Crystal structure and surface morphology were investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. Optical properties of the synthesized $SrAl_2O_4$ : $Eu^{2+}$,$Dy^{3+}$ were measured by photoluminescence (PL) spectrometer for in-depth study on the excitation, emission and afterglow properties. From the PL measurements, it was found that excitation occurred in the wavelength range from 300 to 420 nm with peak position at 360 nm. The emission spectrum showed a broad curve in the wavelength from 450 to 600 nm with peak position at 530 nm. $SrAl_2O_4$ : $Eu^{2+}$,$Dy^{3+}$ phosphors exhibited afterglow properties with emission that lasted for a long period.

• Korean Journal of Optics and Photonics
• /
• v.17 no.6
• /
• pp.556-563
• /
• 2006

We present a comprehensive study of a chirped pulse Ti:sapphire regenerative amplifier system operating at 1 kHz. Main constituents of the system are described in detail. The amplifier stage was first converted to a repetition rate-tunable kHz gain-switched nanosecond Ti:sapphire laser. Operation characteristics at different repetition rates such as build-up times of laser pulses, pump power-dependent output powers and pulse durations, damage thresholds, and tunability ranges were studied. Based on the results achieved, the switching time of the Pocket's cell used and the round trip numbers in the regenerative amplifier were optimized at 1 kHz. The output pulses with a pulse width of 50fs from a home-made Ken lens mode-locked Ti:sapphire oscillator were used as seed pulses. The pulses were expanded to 120ps in a grating stretcher prior to coupling into the 3-mirror amplifier cavity. After amplification and recompression, a stable 1kHz Ti:sapphire regenerative amplifier system, which delivers 85-fs, $320-{\mu}J$ pulses, was fully constructed.