• Journal of Power Electronics
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• 제11권4호
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• pp.401-407
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• 2011

In order to enhance torque density of five-phase permanent magnetic synchronous motor with third harmonic injection for electric vehicles (EVs) applications, optimum seeking method for injection ratio of third harmonic was proposed adopting theoretical derivation and finite element analysis method, under the constraint of same amplitude for current and air-gap flux. By five-dimension space vector decomposition, the mathematic model in two orthogonal space plane, $d_1-q_1$ and $d_3-q_3$, was deduced. And the corresponding dual-plane vector control method was accomplished to independently control fundamental and third harmonic currents in each vector plane. A five-phase PMSM prototype with quasi-trapezoidal flux pattern and its fivephase voltage source inverter were designed. Also, the dual-plane vector control was digitized in a single XC3S1200E FPGA. Simulation and experimental results prove that using the proposed optimum seeking method, the torque density of five-phase PMSM is enhanced by 20%, without any increase of power converter capacity, machine size and iron core saturation.

• Imaging Science in Dentistry
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• 제37권1호
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• pp.9-14
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• 2007

Purpose : To determine the more valuable information to detect the mandibular canal and the mental foramen in panoramic radiographs of a selected Korean population for the implant. Materials and Methods : This study analysed 288 panoramic radiographic images of patients taken at the Dental hospital of Chosun University retrospectively. Indirect digital panoramic X-ray machine (ProlineXC, PLANMECA, Finland) with processing by using Directview $CR950^@$ (Kodak, U.S.A.) and Direct digital panoramic X-ray machine (Promax, PLANMECA, Finland) were used for all exposures. All images were converted into Dicom format. Results : The common position of the mental foramen was in line with the longitudinal axis of the second premolar (68.1%). The mental foramen was symmetrical in 81.8% of cases. The mandibular canal was not identified at anterior portion and discontinued with the mental foramen in 27.8% of all cases, in 42.4% identified with lower border line continued with the mental foramen, in 14.6% with both upper and lower border lines, and in 15.3% unilaterally identified with lower border line. Conclusion : Clinicians can estimate the upper border line of the mandibular canal from the confirmation of the mental foramen and the lower border line of the mandibular canal symmetrically on the panoramic radiography taken in adjusted midsaggital plane of patient's head.

• Journal of electromagnetic engineering and science
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• 제6권3호
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• pp.147-154
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• 2006

In this paper, we propose and present implementation results of a high-speed turbo decoding algorithm. The latency caused by (de) interleaving and iterative decoding in a conventional maximum a posteriori(MAP) turbo decoder can be dramatically reduced with the proposed design. The source of the latency reduction is come from the combination of the radix-4, dual-path processing, parallel decoding, and rearly-stop algorithms. This reduced latency enables the use of the turbo decoder as a forward error correction scheme in real-time wireless communication services. The proposed scheme results in a slight degradation in bit-error rate(BER) performance for large block sizes because the effective interleaver size in a radix-4 implementation is reduced to half, relative to the conventional method. Fixed on the parameters of N=212, iteration=3, 8-states, 3 iterations, and QPSK modulation scheme, we designed the adaptive high-speed turbo decoder using the Xilinx chip (VIRTEX2P (XC2VP30-5FG676)) with the speed of 17.78 Mb/s. From the results, we confirmed that the decoding speed of the proposed decoder is faster than conventional algorithms by 8 times.

• Bulletin of the Korean Chemical Society
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• 제26권7호
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• pp.1017-1024
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• 2005

Elimination reactions of $XC_6H_4CH_2CO_2C_6H_3-2-Y-4-NO_2$ have been studied under various conditions. When X was moderately electron-withdrawing, Y = H, and base-solvent was $R_2$NH-MeCN, the reaction proceeded by the E2 mechanism via an E1cb-like transition state. Concave downward curve was noted in the Hammett plots. When X = 4-$NO_2$, Y = Cl, $CF_3,\;NO_2$, and the base-solvent was ${R_2NH/R_2NH_2}^+$ in 70 mol % MeCN(aq), the reaction proceeded by the E2 mechanism. The mechanism changed to a competing E2 and E1cb when X = 4-$NO_2$ and Y = H, MeO, and to the E1cb when X = 2,4-($NO_2)_2$, and Y = $NO_2$. From these results, a plausible pathway of the change of the mechanism from E2 to the E1cb extreme is proposed.

• 치과방사선
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• 제25권2호
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• pp.375-387
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• 1995

The purpose of this study was to quantitatively evaluated experimental tooth root resorption for digital radiography. For this study, experimentally three root sites were used, and radiograms were taken with standardized apparatus. Digital imaging system were consisted of NEC PC-980l(computer), TRINITRON(monitor), SONY XC-711 CCD camera. The display monitor had a resolution of 512X512 pixels. The obtained results were as follows: 1. In the difference of the four X-ray film of the contrast correction, the contrast difference was one gray scale variation at mean value. 2. Viewing of the view box of the periapical radiographs, experimental tooth root resorption of the periapical area of the first premolar, middle of mesial surface of the first molar mesial root, middle of lingual surface of the first molar distal root were recognized by increased diameter. 3. On the analysis by histogram, the periapical area of the first premolar, the middle of mesial surface of the first molar mesial root were each recognized tooth root resorption of the 5,6,7 pixel, 2,4,5 pixel by increased diameter. 4. On the analysis by histogram, the middle of lingual surface of the first molar distal root was each recognized tooth root resorption of the none, 3,6 pixel by increased diameter.

• 대한치과의사협회지
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• 제53권8호
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• pp.558-568
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• 2015

Objective: The objectives of this study were to measure pediatric organ and effective doses of cone-beam computed tomography (CBCT) for orthodontic analysis and to compare them to those of panoramic and lateral cephalometric radiography, the conventional radiography for orthodontic analysis. Materials and Methods: Alphard VEGA for CBCT, Planmeca Proline XC for panoramic radiography and Orthophos CD for cephalometric radiography were used for this study. Thermoluminescent dosimeter (TLD) chips were located at 24 anatomic sites of 10-year-old anthropomorphic phantom and exposed during CBCT (C-mode; $200{\times}179mm$ FOV), panoramic and lateral cephalometric radiographic procedures at the clinical exposure settings for 10-year-old patient. Pediatric organ and effective doses were measured and calculated using ICRP 2007 tissue weighting factors. Results: Effective doses of CBCT, panoramic radiography and lateral cephlometric radiography in pediatric clinical exposure settings were $292.5{\mu}Sv$, $19.3{\mu}Sv$, and $4.4{\mu}Sv$ respectively. The thyroid gland contributed most significantly to the effective dose in all the radiographic procedures. Conclusion: Effective dose of CBCT was about 12 times to conventional radiographic procedures for orthodontic analysis in pediatric patient. The use of CBCT for orthodontic analysis should be fully justified over conventional radiography and dose optimization to decrease thyroid dose is needed in pediatric patients.

• Bulletin of the Korean Chemical Society
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• 제24권7호
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• pp.993-998
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• 2003

In the aminolysis of phenacyl bromides ($YC_6H_4COCH_2Br$) with benzylamines ($XC_6H_4CH_2NH_2$) in acetonitrile, the Bronsted βx (βnuc) values observed are rather low ( βX = 0.69-0.73). These values are similar to those (βx $^~_=$ 0.7) for other aminolysis reactions of phenacyl compounds with anilines and pyridines, but are much smaller than those ( βx = 1.1-2.5) for the aminolysis of esters with benzylamines which are believed to proceed stepwise with rate-limiting expulsion of the leaving group. The relative constancy of the βx values (βx $^~_=$ 0.7) irrespective of the amine, leaving group and solvent can be accounted for by a bridged type transition state in the rate-limiting expulsion of the leaving group. Thus the aminolysis of phenacyl derivatives are proposed to proceed stepwise through a zwitterionic tetrahedral intermediate ($T^{\pm}$), with rate-limiting expulsion of the leaving group from $T^{\pm}$. In the transition state, the amine is bridged between the carbonyl and α-carbons, which leads to negligible effect of amine on the leaving group expulsion rate.

• Bulletin of the Korean Chemical Society
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• 제26권6호
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• pp.935-938
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• 2005

Nucleophilic addition reactions of benzylamines (BA; $XC_6H_4CH_2NH_2$) to $\alpha-cyano-\beta$-phenylacrylamides (CPA; $YC_6H_4CH=C(CN)CONH_2$) have been investigated in acetonitrile at 25.0 ${^{\circ}C}$. The rate is first order with respect to BA and CPA and no base catalysis is observed. The addition of BA to CPA occurs in a single step in which the addition of BA to $C_{\beta}$ of CPA and proton transfer from BA to $C_{\alpha}$ of CPA take place concurrently with a four-membered cyclic transition state structure. The magnitude of the Hammett ($\rho_X$) and Bronsted ($\beta_X$) coefficients are rather small suggesting an early tansition state (TS). The sign and magnitude of the crossinteraction constant, $\rho_XY$ (= −D0.26), is comparable to those found in the normal bond formation processes in the $S_N2$ and addition reactions. The normal kinetic isotope effect ($k_H/k_D\;{\gt}$ 1.0) and relatively low ${\Delta}H^{\neq}$ and large negative ${\Delta}S^{\neq}$ values are also consistent with the mechanism proposed.

• Imaging Science in Dentistry
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• 제37권2호
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• pp.93-102
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• 2007

Purpose: Cone beam computed tomography (CBCT) provides a lower dose and cost alternative to conventional CT, promising to revolutionize the practice of oral and maxillofacial radiology. The purpose of this study was to evaluate the absorbed and effective doses of Implagraphy and VCT (Vatech Co., Hwasung, Korea) and compare them with those of panoramic radiography. Materials and Methods: Thermoluminescent dosimeter (TLD) chips were placed at 27 sites throughout the layers of Female ART Head and Neck Phantom for dosimetry. Implagraphy, VCT units, and Planmeca Proline XC panoramic unit were used for radiation exposures. Radiation weighted doses and effective doses were measured and calculated using 1990 and 2005 ICRP tissue weighting factors. Results: Effective doses in Sv (ICRP 2005, ICRP 1990) were 90.19, 61.62 for Implagraphy at maxillay molar area, 123.20, 90.02 for Implagraphy at mandibular molar area, 183.55, 139.26 for VCT and 40.92, 27.16 for panoramic radiography. Conclusion: Effective doses for VCT and Implagraphy were only about 2.2 to 4.5 times greater than those for panoramic radiography. VCT and Implagraphy, CBCT machines recently developed in Korea, showed moderately low effective doses.

• Bulletin of the Korean Chemical Society
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• 제28권11호
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• pp.2003-2008
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• 2007

The aminolysis of diphenyl thiophosphinic chloride (2) with substituted anilines in acetonitrile at 55.0 oC is investigated kinetically. Kinetic results yield large Hammett ρX (ρnuc = ?3.97) and Bronsted βX (βnuc = 1.40) values. A concerted mechanism involving a partial frontside nucleophilic attack through a hydrogen-bonded, four-center type transition state is proposed on the basis of the primary normal kinetic isotope effects (kH/kD = 1.0-1.1) with deuterated aniline (XC6H4ND2) nucleophiles. The natural bond order charges on P and the degrees of distortion of 42 compounds: chlorophosphates [(R1O)(R2O)P(=O)Cl], chlorothiophosphates [(R1O)(R2O)P(=S)Cl], phosphonochloridates [(R1O)R2P(=O)Cl], phosphonochlorothioates [(R1O)R2P(=S)Cl], chlorophosphinates [R1R2P(=O)Cl], and chlorothiophosphinates [R1R2P(=S)Cl] are calculated at the B3LYP/ 6-311+G(d,p) level in the gas phase.