• Proceedings of the Optical Society of Korea Conference
• /
• 2002.11a
• /
• pp.172-173
• /
• 2002

An erbium-ytterbium co-doped phosphate glass waveguide amplifier, fabricated by two-step ion-exchange, is presented. The performance of the amplifiers are investigated in viewpoints of net gain, pump power, and noise figure. The waveguide has propagation loss of 0.7 dB/cm Including insertion loss at 1.304 $\mu\textrm{m}$. At a signal wavelength of 1.534 $\mu\textrm{m}$, a high net gain of 12.8 dB and low noise figure of less than 3.9 dB are archived in a 4 cm long waveguide when injected by 140 ㎽ of LD pump at 0.98$\mu\textrm{m}$ in single pass configuration.

• Proceedings of the PSK Conference
• /
• 2003.10b
• /
• pp.170.3-171
• /
• 2003

An efficient Erythropoietin (EPO)-expression system in mammalian cells is required for massive production for therapeutic use. Ammonium ion is a major problem in the production of valuable recombinant proteins in cultured animal cells. Therefore, it is of importance to devise a system by which a high productivity of human therapeutic recombinant protein can be maintained or enhanced under low ammonium concentration. To reduce the ammonium ion accumulated in EPO producing Chinese Hamster Ovary (CHO) ceels, IBE, we introduced the first two genes of the urea cycle, carbamoyl phosphate synthetase (CPSI) and arnithine transcarbamoylase (OTC), into IBE using a stable transfection method. (omitted)

• Environmental Engineering Research
• /
• v.20 no.2
• /
• pp.199-204
• /
• 2015

In this study, a novel phosphorus removal filter made of brass scrubber with higher porosity of over 96% was fabricated and evaluated. The brass scrubber was surface-modified to form copper hydroxide on the surface of the brass, which could be a phosphate removal filter for advanced wastewater treatment because the phosphates could be removed by the ion exchange with hydroxyl ions of copper hydroxide. The evaluation of phosphate removal was performed under the conditions of the batch type in wastewater and continuous type through filters. Filter recycling was also evaluated with retreatment of the surface modification process. The phosphate was rapidly removed within a very shorter contact time by the surface-modified brass scrubber filter, and the phosphate mass of 1.57 mg was removed per gram of the filter. The possibility of this surface-modified brass scrubber filter for phosphorus removal was shown without undesirable sludge production of existing chemical phosphorus removal techniques, and we feel that it would be very meaningful as a new wastewater treatment.

• Korean Journal of Materials Research
• /
• v.28 no.5
• /
• pp.308-314
• /
• 2018

Among the fuel cell electrolyte candidates in the intermediate temperature range, glass materials show stable physical properties and are also expected to have higher ion conductivity than crystalline materials. In particular, phosphate glass has a high mobility of protons since such a structure maintains a hydrogen bond network that leads to high proton conductivity. Recently, defects like volatilization of phosphorus and destruction of the bonding structure have remarkably improved with introduction of cations, such as Zr4+ and Nb5+, into phosphate. In particular, niobium has proton conductivity on the surface because of higher surface acidity. It can also retain phosphorus content during heat treatment and improve chemical stability by bonding with phosphorus. In this study, we fabricate niobium phosphate glass thin films through sol-gel processing, and we report the chemical stability and electrical properties. The existence of the hydroxyl group in the phosphate is confirmed and found to be preserved at the intermediate temperature region of $150-450^{\circ}C$.

• Bulletin of the Korean Chemical Society
• /
• v.21 no.5
• /
• pp.529-531
• /
• 2000

• Korean Journal of Optics and Photonics
• /
• v.11 no.3
• /
• pp.202-205
• /
• 2000

One step thermal potassium ion exchange process was carried out to form optical channel waveguides in an ErNb co-doped phosphate glass. Flowing oxygen gas into KN03 melt during ion exchange was effective to prevent glass surface damage that causes an increase of waveguide propagation loss. Amplification characteristics of the waveguides were evaluated at $1.5{\mu}m$ signal wavelength with 980 om laser diode pump. A 45 mm long waveguide whose processing parameters had been optimized exhibited a small signal net gain of 7.5 dB at the launched pump power of 160 mW.160 mW.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
• /
• 2005.10a
• /
• pp.78-80
• /
• 2005

• Journal of the Korean Chemical Society
• /
• v.19 no.5
• /
• pp.325-330
• /
• 1975

Complex formation between ferric ion and phosphoric acid has been studied in the wide range of the acid concentration(0${\sim}40{\%}$) by uv-visible spectroscopy and by characterization of the isolated products. The electronic spectra of Fe(III)-containing phosphoric acid solutions exhibit two visible bands at 19.2 and 24.1 kK, which are characteristic of Fe(III)-phosphate complex formation. The measurements of acid concentration dependence of the opical density of the 24.1 kK band indicates the presence of two distinct forms of Fe(Ⅲ)-phosphate complexes possibly $[Fe(H_xPO_4)]^{x+}\;and\;[Fe_2 (H_xPO_4)]^{(3+x)+}$. The 1:1 complex has been isolated for characterization, and the phosphate ion was found to be coordinated to the metal in monobasic state whereas the isolation of the dimeric species was unsuccessful.

• Membrane Journal
• /
• v.14 no.2
• /
• pp.117-125
• /
• 2004

Proton exchange membrane composed of PVA/PAM/ZrP was prepared and effect of PAM and ZrP contents on properties and performance of the membrane were investigated. PAM as a crosslinking agent was mixed into PVA solution with different concentration (7∼11 wt%) and the PVA/PAM solution was cast to prepare PVA/PAM crosslinked membrane. The membrane was treated in the solution of zirconyl chloride and phophoric acid to make a PVA/PAM/ZrP composite membrane. Methanol permeability, ion conductivity, swelling and ion exchange capacity of the membranes with different ZrP concentration were $10^{-8}∼l0^{-6}$ $\textrm{cm}^2$/sec, $10^{-3}~10^{-2}$ S/cm, 0.26∼1.17 g $H_2O$/g membrane and 2.59∼5.1 meq/g membrane, respectively. Hethanol permeability and ion conductivity of the PVA/PAM/ZrP membrane were improved by 18% and 23%, respectively, compared to those of the PVA/PAM membrane.

• Journal of Radiation Protection and Research
• /
• v.2 no.1
• /
• pp.24-30
• /
• 1977

Les eaux de $g\'{e}n\'{e}rateur$ de vapeur d'un $r\'{e}acteur$ P. W. R peuvent $\^{e}tre$ $contamin\'{e}es$ par des $radio-\'{e}lements$. Ces eaux sont habituellement $condition\'{e}es$ 'phosphate' pour limiter leur $agressivit\'{e}$ et la tendence actuelle est de remplacer les phosphate par un conditionment 'Amoniaques'. La $pr\'{e}sente$ $\'{e}tude$ a pour but de definir la $possibilit\'{e}$ $d'{\'{e}}purer$ des eaux $condition\'{e}es$ $\'{a}$ l'ammoniaque $\'{a}$ l'aide $d'{\'{e}}changeurs$ d'ion organiques. Des Facteurs de $D\'{e}contamination$ (F. D) en Cesium 137 et Strontium 90 et la $dur\'{e}e$ du cycle $d'{\'{e}}puration$ ont $d\^{u}$ $\^{e}tre$ bien meilleurs avec une colonne de 10 ml de $r\'{e}sine$ Carborylique Duolite $CC_4$ mise sous forme acide, suivie d'une colonne de 10 ml de $r\'{e}sine$ cationique Amberlite IR 120 mise sous forme acide et suivie d'une colonne de 10 ml de $r\'{e}sine$ anionique Amberlite IRA 400 mise sous forme hydroxyde.