• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.17 no.6
• /
• pp.548-557
• /
• 1992

This paper presents how X.25 state machines are defined and procedures are implemented Into the TDI-10 switching system, which Is being developed as an ISDN exchange in Korea.Packet switching is an in important aspect of I SDN. Packet swichedd services in ISDN are defined by X.:31, which provides for the use X.f,j over ISDN B and D-channels between a user and an X.25packet handler. To implement X.2E into an ISDN exchange which Includes a packet handler, X.25state machines and procedures should be adj usted within the ISDN exchange.

• Journal of the Korean Chemical Society
• /
• v.35 no.3
• /
• pp.211-218
• /
• 1991

A series of samples in the $Nd_{-x}Sr_{x}CoO_{3-y}$ system (x = 0.00, 0.25, 0.50, 0.75 and 1.00) have been produced by heating the reactants at 1200${\circ}$C under atmospheric pressure. The solid solutions were analysed by X-ray diffraction spectra, thermal analysis, and SEM micrographs. X-ray powder diffraction assigns the compositions of x = 0.00, 0.25, 0.50 and 0.75 to the cubic system and the composition of x = 1.00 to the orthorhombic system. The reduced lattice volume is increased with increasing x values in the system. The mole ratio of $Co^{4+}$ or ${\tau}$ values are determined by the Iodometric titration method and are maximum at the composition of x = 0.50. The magnetic measurement shows that a ferromagnetism is appeared in the compositions of x = 0.00, 0.25, 0.50 and 0.75 and then an antiferromagnetism in the composition of x = 1.00. The measurement of the electrical conductivity shows that the semiconductivity is appeared in the composition of x = 0.00, 0.25 and 1.00 and the metallic conductivity in the composition of x = 0.50 and 0.75. The magnetic and electrical properties of the samples are discussed with the nonstoichiometric chemical formulas.

• Proceedings of the Korean Institute of Communication Sciences Conference
• /
• 1985.10a
• /
• pp.224-228
• /
• 1985

• Clean Technology
• /
• v.21 no.4
• /
• pp.271-277
• /
• 2015

A photocatalyst which mixed by the commercialized P25-TiO₂ and a synthesized Ag_xO was used in an appropriate weight ratio to effectively produce hydrogen gas in this study. The Ag_xOs were synthesized with the conventional sol-gel method, and tetramethylammonium hydroxides were added at the synthesis process in order to stabilize the solutions, and then the solutions were heat-treated at the temperatures of -5, 25, and 50 ℃, resulted to obtain the three types of silver oxides. Physicochemical properties of the synthesized Ag_xOs were identified through X-ray diffraction analysis (XRD), scanning emission microscopy (SEM), ultraviolet-visible spectroscopy, and X-ray photoelectron spectroscopy (XPS). In the photolysis results of water/methanol (weight ratio 1:1) solution, the mixture of P25-TiO₂/Ag_xO exhibited a significantly higher hydrogen gases evolution, compared to that of pure P25-TiO₂. Additionally, the addition of H₂O₂ as an supplement oxidant and in Ag_xO synthesized at 50 ℃ improved the hydrogen production efficiency. In particular, the emitted hydrogen gases reached to 13,000 μmol during 8 hours when a mixed catalyst, Ag_xO of 0.1 g and P25-TiO₂ of 0.9 g, were used.

• Journal of the Korean institute of surface engineering
• /
• v.51 no.6
• /
• pp.344-353
• /
• 2018

Plasma electrolytic oxidation of Ti-25Ta-xHf alloy in electrolyte containing Ca and P for dental implants was investigated using various experimental techniques. Ti-25Ta-xHf (x=0 and 15 wt.%) alloys were manufactured in an arc-melting vacuum furnace. Micropores were formed in PEO films on Ti-25Ta-xHf alloys in 0.15 M calcium acetate monohydrate + 0.02 M calcium glycerophosphate at 240 V, 270 V and 300 V for 3 min, respectively. The microstructure of Ti-25Ta-xHf alloys changed from (${\alpha}^{\prime}+{\alpha}^{{\prime}{\prime}}$) phase to (${\alpha}^{{\prime}{\prime}}+{\beta}$) phase by addition of Hf. As the applied potential increased, the number of pore and the area ratio of occupied by micro-pore decreased, whereas the pore size increased. The anatase phase increase as the applied potential increased. Also, the crystallite size of anatase-$TiO_2$ can be controlled by applied voltage.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.3 no.2
• /
• pp.103-109
• /
• 1970

The results of this work concerning the growth of the mussel, Mytilus edulis cultured by the hanging method in Koje Bay are as follows: The major spawning time is confined to the period from March to April. The mean growth of the mussel is indicated by the following formula; $$Y\;=\;1.508+0.659X-0.0559X^{2}+0.00367X^3$$ The major growing seasons are June and October The variance varied in proportion to the growth of the mussel, and each ranged, in shell height, from $1.25\~2.75\;to\;2.25\~4.25$ (mean:1.60 to 2.78)cm, $2.25\~5.25(3.00)cm,\;2.25\~7.75(4.83)cm,\;2.25\~7.75(5.05)cm\;and\;2.25\~8.25(5.95)cm$, and the variance were $0.278\~0.230$, 0.368, 0.701, 1.053 and 1.209, respectively. On the other hand, the variances differed in proportion to the growth of the mussel. The average length of the mussel life was about eighteen months. The mussels growing on the hanging line for arrestation undergo seasonal vicissitudes, and the mussels which fall off, mass into countless numbers during the period from August to October and finally disappear completely in November. The dimensions of the largest mussel are as follows: The shell height : 9.48cm The shell length: 4.49cm The shell breath : 3.55cm The shell weight : 22.05g The weight of the soft parts 19.25g The relative growth of the mussel is indicated as follows: Relationship between the shell height and the shell length: Y =0.486X+0.334 Relationship between the shell height and the shell breadth: Y = 0.359X+0.107 Relationship between the weight of the soft part and the shell weight: Y = 0.882X+0.901 Relationship between the shell height and the weight of the soft part: $$Y\;=\;0.02828X^{2.90518}$$

• Proceedings of the Korean Magnestics Society Conference
• /
• 1997.11a
• /
• pp.60-61
• /
• 1997

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.10 no.5
• /
• pp.240-249
• /
• 1985

This paper proposes the requirements of protocol testing, the protocol test methods and the architecture of PTF. Also this paper includes the test sequences and the test results for X.25 DTE packet level protocol.

• Journal of the Korean Magnetics Society
• /
• v.8 no.4
• /
• pp.203-209
• /
• 1998

Crystallographic and magnetic properties of single phase garnet $Y_{3-x}Bi_xFe_5O_{12}$ (x=0.0, 0.25, 0.5, 0.75, 1.0) were studied by using x-ray diffraction, Mossbauer spectroscopy and vibrating sample magnetometer (VSM). Ultra-fine polycrystalline cubic samples have been prepared by sol-gel method. The lattice constant increase linearly with increasing an amount of Bi. Annealing temperature was larger than 800 $^{\circ}C$ for the growth of a single-phase garnet powder. The second phase of garnet, $(BiFeO_3)$, was at 1000 $^{\circ}C$ for x=0.75, and 950 $^{\circ}C$ for x=1.00. From Mossbauer spectroscopy and VSM measurements, the magnetization and the coercivity were decreased and the Curie temperature $Y_{3-x}Bi_xFe_5O_{12}$(x=0.0, 0.25, 0.5, 0.75, 1.0) was slightly increased as increasing the Bi content.

• Communications of the Korean Mathematical Society
• /
• v.25 no.1
• /
• pp.111-117
• /
• 2010

For a based, 1-connected, finite CW-complex X, we denote by $\varepsilon(X)$ the group of homotopy classes of self-homotopy equivalences of X and by $\varepsilon_#\;^{dim+r}(X)$ the subgroup of homotopy classes which induce the identity on the homotopy groups of X in dimensions $\leq$ dim X+r. In this paper, we calculate the subgroups $\varepsilon_#\;^{dim+r}(X)$ when X is a wedge of two Moore spaces determined by cyclic groups and in consecutive dimensions.