• Journal of the Korean Ceramic Society
• /
• v.45 no.10
• /
• pp.625-630
• /
• 2008

In the bone cement composed of dense granules of $\beta-Ca_3(PO_4){_2}(\beta-TCP)$ and $Ca(H_2PO_4){_2}H_2O$, the compressive strength, setting time and temperature rise were measured to observe the degradation of cement with respect to the stored days before setting. Decreases of compressive strength and temperature rise were observed, while setting time increased with respect to the stored days. The similar trends were repeated with the increase of temperature of storage. Such a change virtually meant the fading of the character of cement and it took place only when the two starting materials were mixed during storage. The degradation could be mitigated taking advantage of granular $\beta$-TCP instead of powdery one. The formation of $CaHPO_4$, which resulted from reaction with ambient humidity, was attributed to the degradation observed during storage. Dependence of the degradation behavior on mixing and temperature during storage was discussed in terms of the driving force for reaction of cement.

• Journal of the Korean Vacuum Society
• /
• v.7 no.2
• /
• pp.155-160
• /
• 1998

It is necessary to use Arc layer and DUV resist to define 0.25 $\mu \textrm{m}$ line and space for 256 MDRAM devices. Poly-Si etching with Arc layer and different resists has been performed in a TCP-9408 etcher with variation of gas chemistries; $Cl_2/O_2, Cl_2/N_2, Cl_2$/HBr . DUV resist causes more positive etch profile and CD gain compared to I-line resist because the sidewall passivation is more stimulated by increasing polymerization through the loss of resist. When Arc layer is applied, CD hain also increases due to the polymeric mask formed after thching Arc layer. From the point of gas chemistry effects, the etch profile and CD gain is not improved using $Cl_2/O_2$ gas, since polymerization is accelerated in this gas. however, the vertical profile and less CD gain is obtained using $Cl_2$/HBr gas. Furthermore, HBr gas is very effective to suppress the difference of profile and CD variation between dense pattern and isolated pattern by minimizing non-uniformity of side wall passivation with pattern density.

• Korean Journal of Acupuncture
• /
• v.28 no.3
• /
• pp.85-98
• /
• 2011

Objectives : The aim of this thesis is to examine the effect of acupuncture treatment at the GB37 on normal humans by using the power spectral analysis of the EEG. Methods : EEG (Electroencephalogram) power spectrum exhibits site-specific and state-related differences in specific frequency bands. In this thesis, the power spectrum was measured by the complexity. the 32 channels EEG study was carried out in the 13 subjects (12 males ; age=22.58 years old, 1 females ; 22 years old). Results : In the ${\alpha}$ (alpha) band, the power values at F7, F3, F4, F8, FTC2, C4, T4, CP1, CP2, TCP2, TT2, Pz, P4, Po1, Po2, O1, Oz, O2 channels (p<0.05) during the GB37-acupoint treatment were significantly changed. And in many channels were decreased. In the ${\beta}$ (beta) band, the power values at Cz, C4, T4, Tcp1, T6, Po1, O1, Oz, O2 channels (p<0.05) during the GB37-acupoint treatment were significantly changed. And in many channels were decreased. In the ${\delta}$(delta) band, the power values at Fp1, TT2 channels (p<0.05) during the GB37-acupoint treatment were significantly changed. And in many channels were decreased. In the $\theta$ (theta) band, the power values at Fp1, F8, FTC2, Pz channels (p<0.05) during the GB37-acupoint treatment were significantly changed. And in many channels were decreased. Conclusions : This results suggest that the acupuncture treatment at the GB37 significantly mostly change the power spectrum value on the alpha (18 channels), beta (9 channels) bands.

• Proceedings of the Korean Powder Metallurgy Institute Conference
• /
• 2006.09a
• /
• pp.484-485
• /
• 2006

The process of coprecipitation of biocomposite hydroxyapatite/chitosan from aqueous solution at low temperature in alkali environnement was examined. We have shown that initially we have the formation of amorphous octocalcium phosphates $(Ca_8(HPO_4)(PO_4)_5,\;nH_2O:\;OCP)$ and the transferring from OCP to amorphous calcium phosphate $(Ca_9(PO_4)_3,\;nH_2O:\;TCP)$, and then from TCP to calcium-deficient hydroxyapatite $(Ca_{10-X}\;(HPO_4)_X(PO_4)_{6-x}(OH)_{2-X}\;:\;ACP)$ and hydroxyapatite $(Ca_{10}(PO_4)_6(OH)_2\;:\;HAP)$. The transformation of ACP to HAP was inhibited in the presence of chitosan. The result suggests that there is an affinity binding between ACP and chitosan and subsequently blocking the active growth site of ACP.

• Journal of Korean Society for Atmospheric Environment
• /
• v.21 no.2
• /
• pp.243-257
• /
• 2005

The effects of Traffic Control Program (TCP) on the ambient urban air quality of SO$_{2}$, NO$_{2}$, O$_{3}$, and PM$_{10}$ were evaluated in Seoul metropolitan area by using the lower atmospheric vertical stability index and daily mean wind speeds. The vertical stability index; temperature lapse rate between 1000 hPa and 850 hPa geopotential height fields, were used to identify daily vertical stability index during the 2002 World Cup period where traffic amount was reportedly reduced to half the number of vehicles. The indicated air quality levels of TCP days were then compared with those of the cases observed with analogous vertical stability during the recent 3 years from 2000 to 2002. The result indicates that the effect of TCP on the primary air pollutants are found to be approximately 39$\%$, 23$\%$ and 20$\%$ lower for SO$_{2}$, NO$_{2}$ and PM$_{10}$, respectively. The secondary air pollutant; ozone, showed relatively smaller decreasing rate (13$\%$) of daily mean concentrations (even increased during the night time). The comparison of daily maximum or peak concentrations reveals that the pronounced decreasing effects of TCP on the ambient air quality for both primary and secondary air pollutants, suggesting that TCP is one of the effective strategies to control peak or higher concentrations for most urban scale air pollutants in and around the Seoul metropolitan area.

• Journal of the Korean Ceramic Society
• /
• v.28 no.4
• /
• pp.289-296
• /
• 1991

Hydroxyapatite (HAp)-zirconia bioceramics, which have excellent biocompatibility with tissue of bone and tooth and good mechanical properties, were synthesized, and their properties and biocompatibility were investigated. HAp powders were synthesized with Ca/P=1.67 and pH 11 by precipitation method. A fine spherical monodispersed ZrO2 powders were prepared by metal alkoxide method, and then they were partially stabilized with 10 mol% CaO by solid state reaction at 1300℃. HAp-zirconia composites were prepared by sintering of these HAp mixed with various amount CaO-partially stabillized zirconia (PSZ). When HAp containing 15 wt% PSZ with 10 mol% CaO (PSZ(10C)) were sintered at 1250℃, it was prevented to decompose into TCP and ZrO2 was uniformly dispersed at HAp matrix. Mechanical strength of these sintered bodies were increased by addition of 15 wt% PSZ(10C), the bending strength of compacts fired at 1250℃ was 165 MPa. HAp-PSZ composites chemically bonded each other in Ringer's solution and the component of bonded layer was HAp. These composites did not prevent cell-growing and exhibit any cytotoxic effects.

• Journal of KIISE:Computing Practices and Letters
• /
• v.12 no.2
• /
• pp.102-110
• /
• 2006

This paper explains the design and development of the stand-alone high sound quality Internet Radio system, which is aimed for a small embedded type audio device rather than a general PC type. This device is designed to work with an Internet connection. This kind of system is not standardized so far, and also the related algorithm is not open to the public. So it is necessary to analyze several receiving algorithms of current radio receivers, and develop our own hardware in order to overcome these obstacles, finally to get the high quality of sound radio. The main electronic components of this Internet Radio are TCP/IP interfaces, an audio MP3 decoder, an I/O interface, and a Flash Memory Card with advanced audio multicasting for the next-generation Internet Radio. Basic structures and implementation issues of the next-generation most-versatile digital music player, and Internet Radio receivers, are discussed.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.21 no.11
• /
• pp.1029-1035
• /
• 2008

$LiNi_{1/3}Co_{1/3}Mn_{1/3}O_2$ cathode materials prepared from different precursors in lithium rechargeable batteries were characterized by various analytical methods. $LiNi_{1/3}Co_{1/3}Mn_{1/3}O_2$ powders were synthesized by using solid-state reaction method and their physical and chemical properties were analyzed by XRD, SEM, particle size analyzer and TCP-AES. These materials showed different crystallinity, particle size, surface morphology and chemical composition. Also, the charge/discharge cycling of $LiNi_{1/3}Co_{1/3}Mn_{1/3}O_2$ electrodes was carried out under various cut-off voltages and it showed different behaviors. It was found that the electrochemical cyclability of $LiNi_{1/3}Co_{1/3}Mn_{1/3}O_2$ was strongly related to its crystallinity.

• Archives of Plastic Surgery
• /
• v.37 no.2
• /
• pp.148-152
• /
• 2010

Purpose: In treating diabetic foot ulcers, satisfactory vascularity is an essential prerequisite. To improve vascularity, a bypass graft has long been carried out. Recently, however, percutaneous transluminal angioplasty (PTA) has also been tried since the PTA is less invasive than the bypass graft. However, publication demonstrating the improvement of vascularity after the PTA are lacking. Therefore, this study was designed to show usefulness of the PTA in treating vasculopathy of diabetic foot. Materials: and Methods This study included 30 feet of 24 ischemic diabetic foot patients. Inclusion criteria were diabetes (duration > 5 years) and a significant lower extremity ischemia, as determined by a transcutaneous oxygen pressure ($TcpO_2$) < 30 mmHg. The PTA was carried out in 61 arteries. PTA procedure was considered successful, when residual stenosis was less than 30%. The procedure was considered failed when residual stenosis was more than 50%. Residual stenosis between 30% and 50% was considered acceptable. For evaluation of PTA effect, foot $TcpO_2$ and infrared thermography were measured before and 7th day after PTA. Results: Immediately after PTA performed in 61 arteries, 58 and 3 arteries were evaluated as being successful and acceptable, respectively. Before PTA, average foot $TcpO_2$ was $12.6{\pm}8.8$ mmHg and its value was increased to $44.2{\pm}23.9$ on 7th day after PTA (p<0.01). Average skin temperature was $31.8{\pm}1.2^{\circ}C$ before PTA and it was increased to $33.5{\pm}1.1^{\circ}C$ on 7th day after PTA (p<0.01). Conclusion: PTA procedure increases tissue oxygenation of ischemic diabetic feet which do not have wound healing potential due to low tissue oxygenation, to the level of possible wound healing. In addition, PTA increases skin temperature of ischemic diabetic feet which can imply an improvement of peripheral circulation.

• Journal of the Korean Ceramic Society
• /
• v.33 no.1
• /
• pp.7-16
• /
• 1996

${CO_3}^{2-}$ containing whisker-like hydroxyapatite powders were synthesized byhomogeneous precipitation method using urea, Dicalcium phosphate anhdrate[DCPA; $CaHPO_4$] and octacalcium phosphate [OCP; $Ca_8H_2(PO_4_)6\cdot5H_20$]were obtained as precursors and they transformed to high crystalline hydroxyapatites at pH 5.62, and 6.54 respectively. According to the condition of the final pH in the solutions for the solution products and urea contents OCP was remained. When the solution product of $Ca^{2-}$ and ${PO_4}^{3-}$ was $1.5\times 10^4$[$mM^2$] and the content of urea was 0.25 mol.$dm^{-3}$ well crystallized whisker-like hydroxyapatite tens of micrometer in length was obtained. By heat treatment DCPA and OCP were decomposed into $\beta$-tricalcium phosphate [$\beta$-TCP ; $\beta$-$Ca_3{PO_4}_2$] and $\beta$-dicalcium phosphate [$\beta$-DCP ;$\beta$-$Ca_2P_2O_4}_2$]. And well-crystallized hydroxyapatite was partially decomposed into $\beta$-TCP at $800^{\circ}C$.