• The Journal of the Acoustical Society of Korea
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• v.20 no.4
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• pp.35-41
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• 2001

This paper describes Linear Discriminant Analysis and common vector extraction for speech recognition. Voice signal contains psychological and physiological properties of the speaker as well as dialect differences, acoustical environment effects, and phase differences. For these reasons, the same word spelled out by different speakers can be very different heard. This property of speech signal make it very difficult to extract common properties in the same speech class (word or phoneme). Linear algebra method like BT (Karhunen-Loeve Transformation) is generally used for common properties extraction In the speech signals, but common vector extraction which is suggested by M. Bilginer et at. is used in this paper. The method of M. Bilginer et al. extracts the optimized common vector from the speech signals used for training. And it has 100％ recognition accuracy in the trained data which is used for common vector extraction. In spite of these characteristics, the method has some drawback-we cannot use numbers of speech signal for training and the discriminant information among common vectors is not defined. This paper suggests advanced method which can reduce error rate by maximizing the discriminant information among common vectors. And novel method to normalize the size of common vector also added. The result shows improved performance of algorithm and better recognition accuracy of 2％ than conventional method.

• Journal of the Mineralogical Society of Korea
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• v.22 no.3
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• pp.241-248
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• 2009

Kaolinite was synthesized from amorphous $SiO_2$ and $Al(OH)_3{\cdot}xH_{2}O$ as starting materials by hydrothermal reaction conducted at $250^{\circ}C$ and $30\;kg/cm^2$. The acidity of the solution was adjusted at pH 2. The synthesized kaolinite was characterized by XRD, IR, NMR, FE-SEM, TEM and EDS to clarify the formational process according to the reaction time from 2 to 36 hours. X-ray diffraction patterns showed after 2 h of reaction time, the starting material amorphous $Al(OH)_3{\cdot}xH_{2}O$ transformed to boehmite (AlOOH) and after the reaction time 5 h, the peaks of boehmite were observed to be absent thereby indicating the crystal structure is partially destructed. Kaolinite formation was identified in the product obtained after 10 h of reaction and the peak intensity of kaolinite increased further with reaction time. The results of TGA and DTA revealed that the principal feature of kaolinite trace are well resolved. TGA results showed 13 wt% amount of weight loss and DTA analysis showed that exothermic peak of boehmite observed at $258^{\circ}C$ was decreased gradually and after 10 h of reaction time, it was disappeared. After 5 h of the reaction time, the exothermicpeak of transformation to spinel phase was observed and the peak intensiy increased with reaction time. The results of FT-IR suggested a highly ordered kaolinite was obtained after 36 hours of reaction. It was identified by the characteristic hydroxide group bands positioned at 3,696, 3670, 3653 and $3620\;cm^{-1}$. The development of the hydroxyl stretching between 3696 and $3620\;cm^{-1}$, depends on the degree of order and crystalline perfection. TEM results showed that after 15 h reaction time, curved platy kaolinite was observed as growing of (001) plane and after 36 h, the morphology of synthetic kaolinite exhibited platy crystal with partial polygonal outlines.

• Analytical Science and Technology
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• v.12 no.5
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• pp.421-427
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• 1999

Two shapes of crystals have been isolated by the interdiffusion of $Co(NCS)_2$ dissolved in methanol with 1,2-bis(2,2'-bipyridyl-6-yl)ethane (bbpe) dissolved in chloroform. The two crystals have been elucidated as $trans-Co^{II}(NCS)_2(bbpe)$ and $trans-Co^{II}(NCS)_2(bbpe){\cdot}2CHCl_3$, by X-ray crystallography, elemental analysis, IR, and thermal analysis. The two molecular structures are very similar except for the absence or presence of chloroform solvate molecules. The bbpe ligand coordinates to the cobalt(II) ion in an open-ended tetradentate mode, resulting in discrete mononuclear cobalt(II) complex. The cobalt atom adopts a typical octahedral arrangement with six nitrogen donating atoms with two NCS groups in trans positions. A significant solid-to-solid phase transition occurs presumably due to the change of conformationally flexible bbpe ligand. The formation of both crystals oeeurs in a successive two-step process, the formation of $trans-Co^{II}(NCS)_2(bbpe)$ and its transformation into $trans-Co^{II}(NCS)_2(bbpe){\cdot}2CHCl_3$. The thermal stability and favorable formation of the solvate crystals may be ascribed to the interaction between S atom of NCS group and Cl of chloroform.

• Korean Journal of Materials Research
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• v.19 no.2
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• pp.61-67
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• 2009

Electrolessly deposited Co (Re,P) was investigated as a possible capping layer for Cu wires. 50 nm Co (Re,P) films were deposited on Cu/Ti-coated silicon wafers which acted as a catalytic seed and an adhesion layer, respectively. To obtain the optimized bath composition, electroless deposition was studied through an electrochemical approach via a linear sweep voltammetry analysis. The results of using this method showed that the best deposition conditions were a $CoSO_4$ concentration of 0.082 mol/l, a solution pH of 9, a $KReO_4$ concentration of 0.0003 mol/l and sodium hypophosphite concentration of 0.1 mol/L at $80^{\circ}C$. The thermal stability of the Co (Re,P) layer as a barrier preventing Cu was evaluated using Auger electron spectroscopy and a Scanning calorimeter. The measurement results showed that Re impurities stabilized the h.c.p. phase up to $550^{\circ}C$ and that the Co (Re,P) film efficiently blocked Cu diffusion under an annealing temperature of $400^{\circ}C$ for 1hr. The good barrier properties that were observed can be explained by the nano-sized grains along with the blocking effect of the impurities at the fast diffusion path of the grain boundaries. The transformation temperature from the amorphous to crystal structure is increased by doping the Re.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.8 no.4
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• pp.645-650
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• 1998

Alumina- and yttria-coated SiC powder was prepared by the surface-induced precipitation method, and sintered properties of silicon carbide prepared from this powder were investigated. After a well dispersion of SiC powders in the aqueous solution of $Al_2(SO_4)_3$ and $Y_2(SO_4)_3$, the mixed precursors of aluminum hydroxide, aluminum carbonate, yttrium hydroxide, and yttrium carbonate were precipitated on the surfaces of SiC particles through the hydrolysis reaction of urea. SiC specimens with alumina and yttria exhibit, 97.8% of theoretical density after the sintering at $1900^{\circ}C$ for 2 hrs. During annealing at $2000^{\circ}C$, $\beta$longrightarrow$\alpha$ phase transformation of SiC had taken place and resulted with a rodlike microstructure. Toughness of sintered SiC was enhanced by crack deflection around the rodlike grains. In case of annealing less than that of 3 hr, the fracture toughness of SiC was slightly improved with increasing the amount of sintering aid. However, annealed specimens for a long time showed constant fracture toughness even though the amount of sintering aid increased. It is resulted that the main factor for toughening in annealed SiC for a long time is the pullout effect of rodlike grains during the propagation of cracks, and the amount of sintering aids is less effective on the fracture toughness of SiC.

• Journal of the Korean Ceramic Society
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• v.39 no.3
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• pp.245-251
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• 2002

We prepared γ-alumina beads using the amorphous alumina, obtained by fast calcination of gibbsite, and its were immersed in aqueous solution of the mixture of 21.87% nitric acid and 28.57% acetic acid. The beads thus were hydrothermaly treated at 200$^{\circ}$C for 3h, and were investigated changes of crystal, pore characteristics, $N_2$ adsorption and desorption isotherms, mechanical strengths and thermal resistance. Acicular platelet crystals of 0.1∼0.3${\mu}$m were transformed into acicular boehmite crystals of 1∼2${\mu}$m having the same crystal structure. Through this changes, we found that reversible phase transformation due to hydrothermal reaction took placed between boehmite and ${\gamma}$-alumina. In comparison to the ${\gamma}$-alumina bead before hydrothermal treatment, $N_2$ adsorption capacity was increased from 450㎖/g to 670㎖/g, and pore volume between 100${\AA}$ and 1000${\AA}$ was increased form 0.15㎖/g to 0.77㎖g, and mechanical strength was increased form 1.4MPa to 2.2MPa. Also, it showed the remarkable thermal resistance which sustained ${\theta}$-alumina crystal structure and pores between 100${\AA}$ and 1000${\AA}$ at 1000$^{\circ}$C in 40vol% steam.

• The Journal of Korean Academy of Prosthodontics
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• v.22 no.1
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• pp.51-68
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• 1984

The purpose of this study is primarily to test the use value of tooth ash as an alternative material of the synthetic hydroxyapatite. For this purpose the author performed the experimental study to investigate the phsyical properties of sintered tooth ash and its histocompatibility in vitro. The tooth ash was made by incinerating procedure at $650^{\circ}C,\;750^{\circ}C,\;850^{\circ}C,\;950^{\circ}C\;and\;1050^{\circ}C$ respectively. The composition of tooth ash was analyzed and X-ray diffraction was done. The experimental specimens were molded to the cylinderical form 1 cm high, 1 cm in diameter under the pressure of $1000kg/cm^2$, which were divided into two groups; the one is sintered tooth ash at $1100^{\circ}C$ and the other is fired mixture of tooth ash and dental porcelain mixed to the weight ratio of 4:6, 5:5, 6:4 and 7:3. The physical propoerties of the sintered specimens were examined and their microstructure was observed under the Scanning Electron Microscope. The results obtained were as followings: 1. The difference of the tooth ash composition depending on incinerating temperature was of no significance, but the $CO_2$ disappeared from $950^{\circ}C$. 2. X-ray diffraction showed the tooth ash was mainly composed of hydroxyapatite and a small amount of - white lockite. But phase transformation was not disclosed. 3. The microstructure of the sintered specimens of the ashed tooth powder was of no difference in the structure and grain size accompanying the ashed temperature, but sintering ability seemed to be the best in the specimen incinerated at $950^{\circ}C$. 4. There was good wettability in the mixed sintered specimens of the ashed tooth powder and the porcelain powder. 5. The compressive strength of the sintered specimens of the tooth ash incinerated at $950^{\circ}C$ was the highest with $589.75kg/cm^2$ and the porosity and the absorption were the lowest as well. 6. The mixed sintered specimens of the tooth ash and porcelain powder was good in the physical properties in the case of mixed weight ratio of 6:4. 7. The animal fibroblast cultures with porcelain showed increase in the cell number, whereas the tooth ash showed a small degree of growth inhibition. But the difference of cell multiplication efficiency between control cultures and test cultures with tooth ash was not observed.

• Journal of Korean Neurosurgical Society
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• v.30 no.4
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• pp.443-450
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• 2001

Objective : The cyclin-dependent kinase inhibitor $p27^{kip1}$ protein is a negative regulator of the cell cycle, and its degradation is required for entry into the S phase. Loss of $p27^{kip1}$ expression has been reported to be associated with aggressive behavior in a variety of tumors of epithelial and lymphoid origin. However, its association with various astrocytic tumors has not been clearly demonstrated. We studied to investigate the relationship of $p27^{kip1}$ expression with the biological behavior of astrocytic tumors in addition to study on the role of $p27^{kip1}$ in the tumorigenesis of these tumors. Patients and Methods : From 1990 to 1998, a total of 29 astrocytic tumor of all grades obtained by operative resection were included for evaluation. We studied the expression of $p27^{kip1}$ protein immunohistochemical assay in astrocytic tumors and compared the findings with the clinicopathologic parameters. Immunohistochemical staining was performed on formalin-fixed paraffin-embedded sections by the avidin-biotin-peroxidase complex method. According to WHO classification, all cases were divided into astrocytomas(4 cases), anaplastic astrocytomas(9 cases), and glioblastomas(16 cases) by 3 pathologists. Clinical information was obtained from medical records, and others such as location and size of tumors from imaging studies. Results : Mean $p27^{kip1}$ protein labeling indexes(LI, mean${\pm}$standard deviation) of astrocytomas, anaplastic astrocytomas, and glioblastomas were $80.6{\pm}9.1$, $63.6{\pm}21.0$, and $28.9{\pm}18.7$, respectively, and were inversely correlated with grade of glial tumors(p<0.0001). Mean $p27^{kip1}$ protein LI in the recurrent group was lower than that in the nonrecurrent group, but there was no significant difference statistically(p=0.464). Additionally, $p27^{kip1}$ protein expression did not show any significant relationship to other prognostic factors such as age(p=0.1643), tumor size(p=0.8), or location(p=0.8). Conclusion : These results suggested that reduced expression of $p27^{kip1}$ protein may play a important role in the malignant transformation process of astrocytic tumor cells.

• Journal of Plant Biotechnology
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• v.32 no.4
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• pp.233-241
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• 2005

Plants have considerable advantages for the production of antigenic proteins because they provide an inexpensive source of protein and an easy administration of vaccine. Since a publication describing edible plant vaccine of HBsAg in 1992, a number of laboratories around the world have studied the use of plants as the bioreactor to produce antigenic proteins of human or animal pathogens. Over the last ten years, these works have been mainly focused on three major strategies for the production of antigenic proteins in plants: stable genetic transformation of either the nuclear or plastid genome, or transient expression in plants using viral vectors. As many antigenic proteins have been expressed in tobacco, also several laboratories have succeeded to express genes encoding antigenic proteins in other crop plants: potato, tomato, maize, carrot, soybean and spinach. At present many works for the production of edible plant vaccine against bacteria-mediated diseases have mostly performed the studies of enterotoxins and adhesion proteins. Also the development of new-type antigens (pili, flagella, surface protein, other enterotoxin and exotoxin etc.) is required for various targets and more efficacy to immunize against microorganism pathogens. Many works mostly studied in experimental animals had good results, and phase I clinical trial of LTB clearly indicated its immunogenic ability. On the other hand, edible plant vaccines have still problems remained to be solved. In addition to the accumulation of sufficient antigen in plants, human health, environment and agriculture regulation should be proven. Also oral tolerance, the physiological response to food antigens and commensal flora is the induction of a state of specific immunological unresponsiveness, needs to be addressed before plant-derived vaccine becomes a therapeutic option.

• Science of Emotion and Sensibility
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• v.21 no.2
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• pp.137-144
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• 2018

The study figured out the operational conditions of a two-way movement actuator made of one-way shape memory alloy (OWSMA) for versatile ventilation intelligent garments. To develop a low-power actuator that consumes energy only when a garment changes its form such as opening and closing, multiple channels of OWSMA were used, and optimum diameter of the wires was examined. For the switch device, optimum voltage application unit time was determined. Optimum diameter of OWSMA wire was determined by applying 3.7V to the pre-determined candidate diameters, which demonstrated two-way operation in previous studies. In order to evaluate the optimum voltage application time, the internal diameter of the actuator was measured while increasing and decreasing by 50 ms from the unit time of voltage application. Delay time under two-way operation of the actuator was measured to minimize interference caused by heat between channels. Power of 3.7V was applied to OWSMA for assessment of optimal time, and the whole process from heating to cooling was video-recorded with a thermal image camera to determine the point of time at which the temperature of OWSMA wire dropped below the phase transformation temperature. The results showed that $0.4{\Phi}$ was the most suitable diameter, and the optimum unit time of voltage applied to open and close the actuator was 4100ms. It was also shown that the delay time should be more than 1.8 seconds between two-way operations of the actuator.