• Korean Journal of Optics and Photonics
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• v.10 no.3
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• pp.195-200
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• 1999

We made sharp optical fiber tips with less than 100 nm diameter by using the heating and pulling method with a good repetition and fabricated the photon scanning tunneling microscope (PSTM) using constant intensity mode. The 3-dimensional PZT (Piezoelctric transducer) scanner made of a long PZT tube is consisted of three divided parts, that is, a pair of $\pm$ x and a pair of $\pm$y scanning parts and a z scanning part for the fine approach and scanning. The scanning dimension is 1.43 $\mu\textrm{m}$$\times$1.76 $\mu\textrm{m}$. The height of a optical tip to maintain a constant height within $1/{\lambda}_0$ (${\lambda}_0$ is the incident wavelength) from surface of a specimen to a optical tip is controlled automatically by using the electric feedback circuit. The 3-dimensional shape of standing evanescent waves generated on the surface of a dove prism was measured successfully by using the constant intensity mode PSTM.

• Journal of the Korean Vacuum Society
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• v.17 no.6
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• pp.495-500
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• 2008

The amount of vapor mercury for the generation of glow discharge plasma has been calculated in a fine tube fluorescent lamp having a mixed gas of Ne+Ar including a mercury. When the ionization of atom is considered by the collision between neutral atoms (Ne, Ar, Hg) and electrons of energy $kT_e{\sim}1\;eV$, the density of vapor mercury atom has been obtained as $n(Hg){\sim}3.43{\times}10^{22}m^{-3}$ for the plasma density $n_o{\sim}10^{17}m^{-3}$. In the fluorescent lamps of out diameter 4 mm used for $32{\sim}42$-inch LCD-TVs having a mixture gas of Ne(95%)+Ar(5%) with the pressure of 50 Torr, the quantity of vapor mercury for the glow discharge has been caculated as 0.02{\sim}0.08\;mg$.

• Analytical Science and Technology
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• v.15 no.6
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• pp.502-508
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• 2002

See-through hollow cathode glow discharge cell has been developed for the trace analysis of metal ions. The systems consists of new glow discharge cell improved the cooling system. In the case of previous type of hollow cathode glow discharge cell, it had been utilized for the trace analysis of metal ions but it had a problem that the plasma becomes unstable by air-cooled device. In this study, the modified hollow cathode glow discharge cell has been developed in order to minimize the problem associated with the air-cooled device. thus the stability of the plasma with water-cooling device has been improved and also the higher plasma temperature has been measured. The fundamental characteristics of modified systems have been investigated. And the discharge parameters, such as discharge pressure, material, and diameter of cathode, have been studied to find optimum discharge conditions.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.10 no.6
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• pp.487-495
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• 2017

The thermal characteristics of the electrodeless lamp are one of the main factors that determine the design and performance of the lamp. The coupler changes the impedance characteristic by heat and its use temperature is usually within about $150^{\circ}C$. In this study, we observed the phenomenon when the coupler was exposed at a temperature of $150^{\circ}C$ or higher, which has not been discussed so far. Two types of coupler A and coupler B with different spacing between the inner tube and the coupler were analyzed for electrical, thermal and optical properties and deterioration characteristics with different heat and heat shielding conditions. First, the impedance of the system is obtained and used as a criterion for analyzing the electrical characteristics through it. The diameters of the two types of couplers are 1 mm, and the experimental result shows that the coupler diameter is 1 mm, which can cancel out the loss of the magnetic field strength. Therefore, based on these results, when the coupler is exposed to high temperature of about $200^{\circ}C$, the efficient design method corresponding thereto is proposed.

• Resources Recycling
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• v.9 no.4
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• pp.28-36
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• 2000

This study describes to analyze the characteristics for separation and recovery of both the dried particles and the purified solvent from the waste solvent through the vaporization process by the continuous and instantaneous vacuum drying system. The vacuum drying system for the waste solvents recovery consists of a feeding pump, a double pipe heat exchanger, a vacuum spray chamber, and a condenser. The vacuum drying system heats the waste solvent to the vapor in the double pipe heat exchanger and the expanded vapor is sprayed at the end of the tube. The vaporized solvent in the condenser are recovered. The particles in the waste solvent are separated and dried from the vapor in the vacuum spray chamber. Performance evaluation of the vacuum drying system was conducted using the mixture of the dried pigment particles and benzene or alkylbenzene as test samples. For the mixture of 10 wt% pigment particles an 90% benzene, the recovery efficiency of benzene was 88% with the purity of 99% and the recovery efficiency of dried particles was 94% with the moisture of 1.1 wt%. The size of pigment particles was decreased from $6.5\mu\textrm{m}$ to $5.6\mu\textrm{m}$ in diameter due to high speed spraying and dispersion in the vacuum drying system during drying process. Therefore, the vacuum drying system showed to be an effective method for separating particles and solvent in the waste solvent.

• Resources Recycling
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• v.12 no.3
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• pp.31-37
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• 2003

A study on the characteristics of ammonia desorption from aqueous solutions has been performed by air stripping as the first stage of ammonia recycling for the preparation of ammonium sulfate from it. For air stripping experiments, a stripping column made with acrylic tube of 40 mm diameter was employed and compressed air was injected into solutions through air sparger equipped at the bottom of stripping column. As a result of experiments, the stripping efficiency was increased with the aqueous pH and it was found that the appropriate pH for air stripping of ammonia was between pH 10 and 12. As far as the effect of air flow rate on ammonia stripping was concerned, ammonia stripping was not proportional to the air flow rate although it was affected by the air flow rate to some extent. Moreover, when more than 20 cm of water height was maintained, total ammonia desorbed from solution was not varied with the water height. Stripping temperature was also found to play an important role in ammonia desorption and about 90fo of initial ammonia was desorbed in 14 hours at pH 12.8 and at $60^{\circ}C$ Finally, it was believed that stripping temperature as well as the aqueous pH was one of the most important factors in air stripping of ammonia.

• Applied Chemistry for Engineering
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• v.16 no.2
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• pp.194-199
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• 2005

The principle of vortex cyclone was applied to enhance the treatment efficiency of waste air streams containing particulate matters, phenol, and others. Adsorption, condensation, and/or coagulation could be induced at low temperature zone formed by Joule-Thomson expansion as the pressurized air and pulverized activated carbon were introduced at the tangential direction into the cyclone system applied with the coaxial funnel tube of vortex cyclone. Easily condensible vapors were adsorbed and/or condensed forcibly on coagulated or condensed materials which were formed as cores for coagulation or condensation by themselves or on pulverized activated carbons. These types of coagulation or condensation rates were rapidly promoted by increase in their diameter. The maximum removal efficiency obtained from this experiment for the removal of carbon dioxide and phenol was about 87.3 and 93.8 percent, respectively. Phenol removal efficiency was increased with the relative humidities and enhanced by pulverized activated carbon added. The Joule-Thomson coefficients were increased with the pressure of air injected in the range of the relative humidities between 10% and 50%. It is believed that the moisture, particulate matters, and the pressure of the process air introduced could control the removal efficiency of VOCs.

• Journal of Korean Society of Forest Science
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• v.7 no.1
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• pp.19-27
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• 1968

As a preliminary investigation to obtain useful auto- and allopolyploids a ten year old tetraploid of Pinus densiflora induced from the colchicine treated seed was observed on the cytological, morphological and physioa logical characters in the present study and the results can be summarized as follows. 1. The number of chromosome at the base of needle was 48 so that it was recognized as a tetraploid. 2. The needles were thicker and the number of them on an individual was less than the 2n plant. The needle combined to a single was appeared 2%. 3. No difference was found in the number of stomata rows on the central part of needle between the tetraploid and 2n plant, however, guard cells of tetraploid increased 36% in the long diameter compared with 2n plant. 4. Microsporangiate storbile developed normally showing the same size with 2n plant while the size of pollen grain increased about 20% larger than 2n plant. 5. Germination percentage in vitro increased until 17 hours but decreased after 26 hours compared with 2n plant. The longest length of pollen tube during the germination period appeared in the tetraploid pollen.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.2
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• pp.68-75
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• 2022

In this study, in order to directly evaluate the prestress of the PSC structure, a new sensor module based on the measurement of the deformation of concrete was proposed using hetero-core optical fibers and performance tests were performed. In a hetero-core optical fiber, optical loss occurs when a specific part of the transmission path is bent, and the amount of optical loss changes linearly according to the magnitude of the curvature. In order to confirm the measurement performance of the sensor module and the applicability of the optical fiber, the sensor module was deformed and the light passing through the optical fiber was converted into wattage and measured. It can be seen that the light passing through the optical fiber has a linearity of 0.9333 in relation to the deformation while generating the maximum deformation of 0.5 mm at a rate of 0.12 mm/min in a cylindrical concrete specimen with a diameter of 15 cm and a height of 35 cm in which the sensor module is embedded. Based on the results of this experiment, it is judged that it is possible to directly evaluate the prestress of a PSC structure by embedding a sensor module using a hetero-core optical fiber in the structure and measuring the compression deformation in concrete. It is judged that it can be used as useful data for the development of a sheath tube integrated sensor module to be applied to be applied to the girder model experiment.

• Clean Technology
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• v.16 no.2
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• pp.124-131
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• 2010

Effects of $Ca(OH)_2$ concentration (0.16~0.64 wt%), surfactant concentration (2~16 wt%), total volumetric flow rate (3~6 L/min) and $CO_2$ volume fraction $(0.3{\sim}0.6)$ on morphology, crystal structure, mean particle diameter, aggregation and specific surface area of the precipitated $CaCO_3$ were investigated in the slurry bubble column reactor. Experiments were carried out in acrylic reactor ($0.11\;m-ID{\times}1.0\;m-high$) with a internal tube ($0.04\;m-ID{\times}1.0\;m-high$h). The reaction time of $CaCO_3$ synthesis decreased with adding Dispex N40 of the anionic surfactant. The reaction rate of $Ca(OH)_2$ increased with increasing the volumetric flow rate of $CO_2$. From SEM images, the single crystal of $CaCO_3$ increased with increasing the reaction rate in the saturated concentration of $Ca(OH)_2$ (0.16 wt %) and the concentration of Dispex N40 (2 wt%). The mean particle size of $CaCO_3$ varied with adding Dispex N40. In addition, the specific surface area of $CaCO_3$ increased with adding of surfactant (2 wt%) from $35m^2/g$ to $44m^2/g$ at the volumetric flow rate of $CO_2$ (0.9 L/min) and the concentration of $Ca(OH)_2$(0.64 wt %).