• The Transactions of the Korean Institute of Electrical Engineers C
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• v.50 no.9
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• pp.427-433
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• 2001

A linear ultrasonic motor was designed by a combination of the first longitudinal and fourth bending mode, and the motor consisted of a straight aluminum alloys bar bonded with a piezoelectric ceramic element as a driving element. That is,$L_1-B_4$ linear ultrasonic motor can be constructed by a multi-mode vibrator of longitudinal and bending modes. Linear ultrasonic motors are based on an elliptical motion on the surface elastic body, such as bar or plates. In general, the natural resonance frequency of the stator is used as a driving frequency of the motor which provides a large elliptical motion. The corresponding eigenmode of one resonance frequency can be excited twice at the same time with a Phase shift of 90 degrees in space and time. And the rotation can be reversed by changing the phase between the two signals from sin$\omega$t to cos$\omega$t. Moreover, the tangential force pushes the slider(rotor) and, therefore, determines the thrust and speed of the motor. The experimental results of fabrication motors, bimorph-tyPe motor showed more excellent than unimorph-type. The maximum speed of TBL-200, TBL-300, TBL-400, TBL -220, TBL-310 and TBL-420 motors were 0.12, 0.37, 0.39, 0.14, 0.55 and $0.60ms6{-1}$, respectively. And the efficiency were reported 1.15, 7.9, 6.6, 2.36, 10.1 and 16.5%, respectively. That time, output thrust of the motor was a strong(1~2N) and the weight of stator was a lightness(5~7g).

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.12
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• pp.1351-1358
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• 2014

This study numerically simulates brake squeal and validates it experimentally by using a lab-scaled brake dynamometer. The system frequencies of the disc brake are traced with respect to the brake pressure by using a modal test and FEM. Then, the squeal frequencies measured from the brake dynamometer are found to correspond to the brake system mode with the dominant displacement of the caliper and pad. Furthermore, a complex eigenvalue analysis conducted using the finite element model confirms that the caliper mode generating the rotational displacement of the pad becomes unstable owing to the negative friction-velocity slope.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.11
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• pp.919-925
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• 2016

In this study, the Lamb wave mixing technique, which is basised on advanced research on the nonlinear bulk wave mixing technique, is applied for corrosion detection. To demonstrate the validity of the Lamb wave mixing technique, an experiment was performed with normal and corroded specimens. Comparison group in an experimentation are selected to mode and frequency with dominant in-plane displacement and out-of-plane displacement of Lamb waves. The results showed that the Lamb wave mixing technique can monitor corrosion defects, and it has a trend similar to that of the conventional Lamb wave technique. It was confirmed that the dominant displacement and mode matching the theory were generated. Flaw detectability is determined depending on displacement ratio instead of using the measurement method and mode selection.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.4A
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• pp.365-372
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• 2007

In IEEE 802.11b wireless network, stations synchronize themselves to the beacons periodically sent by the access point(AP) when they are running in low power mode. In case of missing beacon due to noise or traffic from neighboring wireless network stations must be awake until they get the next beacon, which causes energy consumption in stations. In this paper, we propose a scheme searching next beacon consuming little energy. The problems of missing beacon in low power mode of IEEE 802.11b wireless interface are described and a new method to reduce energy consumption is proposed. The proposed method is simulated with the network simulator, ns2, and compared with the low power mode of the IEEE 802.11b. The result measured in terms of station's wakeup time shows some enhancement in energy consumption when some errors occur in receiving frames.

• Mass Spectrometry Letters
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• v.5 no.1
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• pp.24-29
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• 2014

An advanced and reliable high performance liquid chromatography (HPLC)/ultraviolet detector (UV)/ion-trap time-of-flight (IT-TOF) mass spectrometry was developed for the simultaneous quantification of 19 marker compounds in Bang-poong-tong-sung-san (BPTS), a traditional oriental prescription. Various parameters affecting HPLC separation and IT-TOF detection were investigated, and optimized conditions were identified. The separation was achieved on a Capcell PAK C18 column ($1.5mm{\times}250mm$, $5{\mu}m$ particle size) using a gradient elution of acetonitrile and water containing 0.1% formic acid at a flow rate of 0.1 mL/min. The column temperature was maintained at $40^{\circ}C$ and the injection volume was $2{\mu}L$. IT-TOF system was equipped with an electrospray ion source (ESI) operating in positive or negative ion mode. The optimized electrospray ionization parameters were as follows: ion spray voltage, +4.5 kV (positive ion mode), or -3.5 kV (negative ion mode); drying gas ($N_2$), 1.5 L/min; heat block temperature, $200^{\circ}C$. Automatic $MS^n$ (n = 1~3) analyses were carried out to obtain structural information of analytes. Elemental compositions and their mass errors were calculated based on their accurate masses obtained from a formula predictor software. The marker compounds in BPTS were identified by comparisons between $MS^n$ spectra from standards and those from extracts. Moreover, the libraries of $MS^2$ and $MS^3$ spectra and accurate masses of parent and fragment ions for marker compounds were constructed. The developed method was successfully applied to the BPTS extracts and identified 17 out of 19 marker compounds in the BPTS extracts.

• Journal of Korean Physical Therapy Science
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• v.9 no.4
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• pp.7-14
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• 2002

The drug therapy for rheumatoid arthritis must be maintained constantly or for the whole life but is apt to induce the adverse effects in gastrointestinal or renal system. Therefor, newer methods are paid attention to reduce adverse effects. The thirty-two rat female separated into seven groups depending on the therapy or Freund's adjuvant applied: Normal group(n=8) not received anything, Positive control group(n=8) only received adjuvant, USC group(n=8) received continuous US, USP group(n=8) received pulsed US. The physical and radiological findings by thermal and non-thermal effects of ultrasound were evaluated in groups with continuous mode at 1 MHz, $0.5\;W/cm^2$ for 6 minutes and with pulsed mode (duty cycle 1:9) at 1 MHz, $0.5\;W/cm^2$ for 6 minutes. The result summarized followings. 1. Swelling of forepaw and hindpaw was significantly reduced in USP. 2. Arthritis indices in USP group were significantly reduced than those in PCG. 3. In naked eye and radiologic findings, swelling was significantly prevented in USP group but not in PCG. The change of swelling, arthritis index, gross feature in naked eye, radiologic finding were significantly improved in all groups except for USC group, taking care for using its continuous mode.

• Tuberculosis and Respiratory Diseases
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• v.42 no.3
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• pp.351-360
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• 1995

Background: Pressure support(PS) is becomimg a widely accepted method of mechanical ventilation either for total unloading or for partial unloading of respiratory muscle. The aim of the study was to find out if PS exert different effects on respiratory mechanics in synchronized intermittent mandatory ventilation(SIMV) and continuous positive airway pressure (CPAP) modes. Methods: 5, 10 and 15 cm $H_2O$ of PS were sequentially applied in 14 patients($69{\pm}12$ yrs, M:F=9:5) and respiratory rate (RR), tidal volume($V_T$), work of breathing(WOB), pressure time product(PTP), $P_{0.1}$, and $T_1/T_{TOT}$ were measured using the CP-100 pulmonary monitor(Bicore, USA) in SIMV and CPAP modes respectively. Results: 1) Common effects of PS on respiratory mechanics in both CPAP and SIMV modes As the level of PS was increased(0, 5, 10, 15 cm $H_2O$), $V_T$ was increased in CPAP mode($0.28{\pm}0.09$, $0.29{\pm}0.09$, $0.31{\pm}0.11$, $0.34{\pm}0.12\;L$, respectively, p=0.001), and also in SIMV mode($0.31{\pm}0.15$, $0.32{\pm}0.09$, $0.34{\pm}0.16$, $0.36{\pm}0.15\;L$, respectively, p=0.0215). WOB was decreased in CPAP mode($1.40{\pm}1.02$, $1.01{\pm}0.80$, $0.80{\pm}0.85$, $0.68{\pm}0.76$ joule/L, respectively, p=0.0001), and in SIMV mode($0.97{\pm}0.77$, $0.76{\pm}0.64$, $0.57{\pm}0.55$, $0.49{\pm}0.49$ joule/L, respectively, p=0.0001). PTP was also decreased in CPAP mode($300{\pm}216$, $217{\pm}165$, $179{\pm}187$, $122{\pm}114cm$ $H_2O{\cdot}sec/min$, respectively, p=0.0001), and in SIMV mode($218{\pm}181$, $178{\pm}157$, $130{\pm}147$, $108{\pm}129cm$ $H_2O{\cdot}sec/min$, respectively, p=0.0017). 2) Different effects of PS on respiratory mechanics in CP AP and SIMV modes By application of PS (0, 5, 10, 15 cm $H_2O$), RR was not changed in CPAP mode($27.9{\pm}6.7$, $30.0{\pm}6.6$, $26.1{\pm}9.1$, $27.5{\pm}5.7/min$, respectively, p=0.505), but it was decreased in SIMV mode ($27.4{\pm}5.1$, $27.8{\pm}6.5$, $27.6{\pm}6.2$, $25.1{\pm}5.4/min$, respectively, p=0.0001). $P_{0.1}$ was reduced in CPAP mode($6.2{\pm}3.5$, $4.8{\pm}2.8$, $4.8{\pm}3.8$, $3.9{\pm}2.5\;cm$ $H_2O$, respectively, p=0.0061), but not in SIMV mode($4.3{\pm}2.1$, $4.0{\pm}1.8$, $3.5{\pm}1.6$, $3.5{\pm}1.9\;cm$ $H_2O$, respectively, p=0.054). $T_1/T_{TOT}$ was decreased in CPAP mode($0.40{\pm}0.05$, $0.39{\pm}0.04$, $0.37{\pm}0.04$, $0.35{\pm}0.04$, respectively, p=0.0004), but not in SIMV mode($0.40{\pm}0.08$, $0.35{\pm}0.07$, $0.38{\pm}0.10$, $0.37{\pm}0.10$, respectively, p=0.287). 3) Comparison of respiratory mechanics between CPAP+PS and SIMV alone at same tidal volume. The tidal volume in CPAP+PS 10 cm $H_2O$ was comparable to that of SIMV alone. Under this condition, the RR($26.1{\pm}9.1$, $27.4{\pm}5.1/min$, respectively, p=0.516), WOB($0.80{\pm}0.85$, 0.97+0.77 joule/L, respectively, p=0.485), $P_{0.1}$($3.9{\pm}2.5$, $4.3{\pm}2.1\;cm$ $H_2O$, respectively, p=0.481) were not different between the two methods, but PTP($179{\pm}187$, $218{\pm}181 cmH_2O{\cdot}sec/min$, respectively, p=0.042) and $T_1/T_{TOT}$($0.37{\pm}0.04$, $0.40{\pm}0.08$, respectively, p=0.026) were significantly lower in CPAP+PS than in SIMV alone. Conclusion: PS up to 15 cm $H_2O$ increased tidal volume, decreased work of breathing and pressure time product in both SIMV and CPAP modes. PS decreased respiration rate in SIMV mode but not in CPAP mode, while it reduced central respiratory drive($P_{0.1}$) and shortened duty cycle ($T_1/T_{TOT}$) in CPAP mode but not in SIMV mode. By 10 em $H_2O$ of PS in CPAP mode, same tidal volume was obtained as in SIMV mode, and both methods were comparable in respect to RR, WOB, $P_{0.1}$, but CPAP+PS was superior in respect to the efficiency of the respiratory muscle work (PTP) and duty cycle($T_1/T_{TOT}$).

• Journal of the Korean Society of Clothing and Textiles
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• v.5 no.2
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• pp.1-12
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• 1981

Nous avons essaye, dans cette etude, de deceler les caracteristiques de la silhouette du style d'Empire en eclairant it la fois le processus de sa formation ai travers La Monarchie, La Republique, Le Directoire, Le Consulat et l'Empire. Nous avons souligne comme suit: En premier lieu, comme les caracteristiques generaux, la simp lification et la democratisation. En second lieu, comme celles de La Monarchie et de La Republique, la transformation renovatrice en forme grossiere du style cylindriforme de la mode d'epoque ancienne. En troisieme lieu, comme celles du Directoire, la formation de l'unite esthetique au haut degre et les lignes naturelles du corps. En quatrieme lieu, comme celles du Consulat et de l'Empire, l'achevement du style d'Empire d'ornement somptueux refletant l'autorite politique de l'Empereur.

• Analytical Science and Technology
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• v.6 no.4
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• pp.349-357
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• 1993

Analytical methods of thromboxane $B_2(TXB_2)$ using various techniques of Fast Atom Bombardment mass spectrometry (FAB MS) were studied, static FAB condition was investigated to obtain linear response curve using docosanoic acid as a internal standard. For maximum sensitivity, a continuos-flow(CF-) FAB MS by selected-ion monitoring(SIM) with devised sample introduction system, has been developed to quantiate thromboxane $B_2$ in biological sample. Instrumental parameters affecting sensitivity, reproducibility has been studied. The method has been optimized with respect to the eluent, 0.75% glycerol(in EtOH v/v) and flow rate of $3.7{\mu}l/min.$ Under the condition, detection limits were below 10pg in SIM mode and a good linear relationship between dose and response was achieved.

• KSBB Journal
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• v.15 no.4
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• pp.346-351
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• 2000

Several solvents or combinations of solvents were tested for the extraction of wet or dried biomass at different extraction mode from plant cell cultures. Methanol gave the highest paclitaxel recovery with the least amount of solvent usage. before extraction drying of biomass wass helpful to decrease solvent usage in extraction step./ in this case drying method was very important to obtain high yield from dried biomass. In thid mode of operation counter-current extraction process can be able to decrease solvent usage but paclitaxel recovery was almost same with both batch and counter-current mode of operation. The number of extraction times was at least four to obtain high yield(>99%) from cell and one to obtain highyield(>96%) from cell debris in batch mode. Equilibrium (i.e. the ratio of paclitaxel in biomass to paclitaxel in the extraction solvent) was reached within 5 minutes. The minimum methodal concentration (90%) and solvent amount(biomass : solvent=1 Kg : 1L) are enough to obtain high yield(>98%) for extraction from biomass.