• Korean Journal of Acupuncture
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• v.23 no.1
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• pp.15-36
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• 2006

Objectives . The aim of this study was to examine the effect of electroacupuncture(EA) at the ST36 on normal humans by using power spectral analysis. Methods : EEG(Electroencephalogram) power spectral exhibits site-specific and state-related differences in specific frequency bands. In this study, power spectrum was used as a measure of complexity. 32 channel EEG study was carried out in 12 subjects (10 males; age=26.7 years old, 2females; age=28 years old). Results ; In ${\alpha}$ (alpha) band, the power values at Fp2, F7, F3, Fz, FTC1, FTC2, T3, C3, Cz, C4, TT1, TCP1, CP1, CP2,T5, P3, Pz, P4, Po1, Po2, O1, Oz,O2 channels(p<0.05) during the ST36-acupoint treatment were significantly increased. In ${\beta}$ (beta) band, the power values at Fp2, F7, F3, Fz, F4, F8, FTC1, FTC2, T3, C3, Cz, C4, TT1, TCP1, CP1, CP2, T5, P3, Pz, P4, Po1, Po2, O1, Oz, O2 channels(p<0.05) during the ST36-acupoint treatment were significantly decreased. In ${\delta}$ (delta) band, the power values at F7, Fz, T3, C3, TT1, TCP1, CP1, CP2, T5, P3, Pz,T6, Po1, PO2,O1, Oz, O2 channels(p<0.05) during the ST36-acupoint treatment were significantly decreased. In ${\theta}$(theta) band, the power values at F7, Fz, FTC1, T3, TCP1, CP2, TCP2, Po1, Po2 channels(p<0.05) during the ST36-acupoint treatment were significantly decreased. ${\alpha}$/${\beta}$ values at Cz, T5, O1, Oz, O2 channels during the ST36-acupoint treatment were increased. ${\beta}$/${\theta}$ values at Fpl, F7, F3, Fz, F4, F8, FTC1, FTC2, T3, C3, C4, T4, TT1, TCP1, TCP2, TT2, P3, P4, T6, Pol channels during the ST36-acupoint treatment were increased. Conclusions : This results suggest that Electroacupuncture at the ST36 mostly affects the charge on alpha(23 channels), beta(25 channels) bands.

• Advanced Composite Materials
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• v.18 no.3
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• pp.287-295
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• 2009

$\beta$-Tricalcium phosphate ($\beta$-TCP) particles reinforced bioresorbable plastics poly-L-lactide (PLLA) composites were prepared by injection molding. The nominal weight ratio of $\beta$-TCP was selected as 5, 10 and 15%. In order to clarify effects of the PLLA crystallinity on the mechanical properties, the specimens were heat treated isothermally. Results of differential scanning calorimetry indicated that the PLLA crystallinity increased with increasing heat treatment temperature. Bending and compressive tests were conducted on the specimen with different $\beta$-TCP contents and crystallinities. The results show that the bending and compressive moduli increased with increasing $\beta$-TCP contents and crystallinity. On the other hand, bending strength decreased with increasing $\beta$-TCP contents. Maximum bending strength was obtained at the heat treatment of $70^{\circ}C$ for 24 h, whereas compressive 0.2% proof strength increased with increasing heat treatment temperature. This difference is attributed to the difference in the microscopic damages.

• Journal of the Korean Ceramic Society
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• v.53 no.6
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• pp.670-675
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• 2016

Calcium phosphate crystallites were prepared by wet chemical method for use in artificial bone. In order to obtain ${\beta}$-tricalcium phosphate (TCP), nano-crystalline calcium phosphate (CaP) was precipitated at $37^{\circ}C$ and at $pH5.0{\pm}0.1$ under stirring using highly active $Ca(OH)_2$ in DI water and an aqueous solution of $H_3PO_4$. The precipitated nano-crystalline CaP solution was kept at $90^{\circ}C$ for the growth of CaP crystallites. Through the growing process of CaP crystallites, we were able to obtain various sizes of rectangular CaP crystallites according to the crystal growing times. Dry nano-crystalline CaP powders at $37^{\circ}C$ were mixed with dry macro-crystalline CaP crystallites and the shaped mixture sample was fired at $1150^{\circ}C$ to make a ${\beta}-TCP$ block. Several tens of nm powders were uniformly coated on the surface, which was comprised of powders of several tens of ${\mu}m$, using a vibrator. The mixing ratio between the nanometer powders and the micrometer powders greatly affected the mechanical strength of the mixture block; the most appropriate ratio of these two materials was 50 wt% to 50 wt%. The sintered block showed improved mechanical strength, which was caused by the solid state interaction between the nano-crystalline ${\beta}-TCP$ and the macro-crystalline ${\beta}-TCP$.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.39 no.1
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• pp.31-38
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• 2002

In order to improve the 0.35 $mutextrm{m}$-via hole etching process the etching characteristic of the gas $C_2F_{6}$ has been analyzed. The samples were triple-layer films(TEOS/SOG/TEOS) on 8-inch wafers and the orthogonal array matrix technique was used for the process. The equipment for etching was the transformer coupled plasma (TCP) source which is a type of high density plasma(HDP). This experiment showed the etching rate for $C_2F_{6}$ was 0.8 $mutextrm{m}$/min-1.1 $mutextrm{m}$/min and the measured uniformity was under $pm$6.9% in the matrix window. The CD skew comparison between pre and post-etching was under 10% which is an outstanding results in the window of profile in anisotropic etching. There was no problem in C2F6 with the flow rate of 20sccm, but when 14sccm of $C_2F_{6}$ was supplied there was a recess problem on the inner wall of SOG film. Consequently the etching characteristic of $C_2F_{6}$ shows a fast etching rate and a very wide process window in HDP TCP.

• The KIPS Transactions:PartC
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• v.10C no.5
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• pp.595-602
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• 2003

In this paper, we proposed new buffer management and cell scheduling scheme of GFR service for improving fairness of TCP/IP traffic in ATM networks. The proposed algorithm used untagged cell, which came to ATM switch, to decide the policy for discard of frame and what kind of VC cell it would serve. Performance analysis through the simulation present that proposed scheme can meet fairness 2 (MCR Plus equal share), which are not met by conventional scheduling mechanism such as WRR. Also, proposed scheme is superior to WRR about 30% in throughput and more efficiency in fairness criteria.

• The KIPS Transactions:PartC
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• v.12C no.4 s.100
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• pp.571-580
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• 2005

In fast long-distance networks, TCP's congestion control algorithm has the problem of utilizing bandwidth effectively. Several window-based congestion control protocols for high-speed and large delay networks have been proposed to solve this problem. These protocols deliberate mainly three properties : scalability, TCP-friendliness, and RTT-fairness. These protocols, however, cannot satisfy above three properties at the same time because of the trade-off among them This paper presents a new window-based congestion control algorithm, called EM (Exponential Increase/ Multiplicative Decrease), that simultaneously supports all four properties including fast convergence, which is another important constraint for fast long-distance networks; it can support scalability by increasing congestion window exponentially proportional to the time elapsed since a packet loss; it can support RTT-fairness and TCP-friendliness by considering RTT in its response function; it can support last fair-share convergence by increasing congestion window inversely proportional to the congestion window just before packet loss. We evaluate the performance of EIMD and other algorithms by extensive computer simulations.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.9
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• pp.756-760
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• 2007

Flame retardant(FR) properties were investigated with tricredyl phosphate(TCP) and tris(pentafluorophenyl)phosphine(TFPP) as additives for lithium-ion batteries. Thermal stability was improved with additives in $Li/LiNi\frac{1}{3}Mn\frac{1}{3}Co\frac{1}{3}O_2$ cells comparing to non-additive electrolytes. Oxygen evolution reaction of the cathode material was delayed to up $55^{\circ}C$, from $275^{\circ}C\;to\;330^{\circ}C$. Electrolytes with the 1 wt.% additives provided good FR properties while the resonable battery performance is maintained.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.15 no.2
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• pp.79-85
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• 2005

Commercial hydroxyapatite (HA) powders were calcined at the temperature range of $1000{\sim}1350^{\circ}C$ in air, for 2h, and the calcined powders were immersed in simulated body fluid (SBF) of pH 7.4 at $37^{\circ}C$ for 3 or 7 days. Thermal decomposition and their related dissolution behaviors of hydroxyapatite were investigated by XRD, FT-IR, and TEM. At the temperature of $1200^{\circ}C$, HA gradually releases its $OH^-$ ions and transforms to OHAP((oxyhydroxyapatite, ($Ca_{10}(PO_4)_6O_x(OH)_{2-2x}$)). HA thermally decomposes to ${\alpha}-TCP$ (${\alpha}-tricalcium$ phosphate) and TTCP (tetracalcium phosphate) phase at $1350^{\circ}C$. It was found that the surface dissolution of the hydroxyapatite powders was accelerated by non-stoichiometric composition and decomposed to ${\alpha}-TCP$ and TTCP.

• Korean Journal of Materials Research
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• v.28 no.3
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• pp.142-147
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• 2018

${\beta}-Tricalcium$ phosphate (TCP) was added to $Al_2O_3$ to make a biomaterial with good mechanical properties. Using a TCP powder synthesized by a polymer complexation method, $Al_2O_3$ composites containing 30 wt% TCP were fabricated and characterized for densification, phase, microstructure, strength, and fracture toughness. With optimizing the powder preparation conditions, a high densification of 97 % was obtained by sintering at $1350^{\circ}C$ for 2 h. No reaction between the two components occurred and there was no transition to ${\alpha}-TCP$. TCP grains with a size of $2-4{\mu}m$ were well surrounded by $Al_2O_3$ grains with a size of $1{\mu}m$ or less. Strength 61(Brazilian) or 187(3-p MOR) MPa, and fracture toughness 1.7 (notched beam) or 2.5 (indentation) $MPa{\cdot}m^{1/2}$ were obtained, which are large improvements over the strength of $TCP/Al_2O_3$ composites and toughness of TCP and hydroxyapatite in previous studies.

• Journal of the Korean Ceramic Society
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• v.30 no.11
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• pp.905-910
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• 1993

$\alpha$-tricalcium phosphate($\alpha$-TCP) powders were synthesized and their hydration properties were investigated in Tris. solution. Two kinds of $\alpha$-TCP powder samples were prepared; the one is reaction product of CaHPO4.2H2O and CaCO3, and another is that of hydroxyapatite(HAp) and $\beta$-Ca2P2O7. They were satisfied with Ca/P mole ratio 1.5 and were heated at 150$0^{\circ}C$ for 5 hours. In the hydration of $\alpha$-TCP samples the powder which was synthesized from HAp and $\beta$-Ca2P2O7 was hydrated faster than that from CaHPO4.2H2O and CaCO3. The hydration reaction of $\alpha$-TCP powder transformed rapidly into HAp accompanying setting and hardening. It was realized that the hydration reaction of $\alpha$-TCP was due to the solution-precipitation mechanism and the hydrates from the reaction were Ca-deficient HAp having funtional group HPO42-.