• Journal of the Korean Society for Railway
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• v.14 no.6
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• pp.495-500
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• 2011

In evaluating the ride comfort of railway vehicles, relationship between passenger's feeling and vibration characteristics is very important because human feeling is dependent on frequency spectrum of vibration. Therefore, the weighing curves in frequency domain are used to evaluate the ride comfort of railway vehicles. These curves have been defined in the Laplace transfer functions. It is necessary to convert the Laplace weighing function to the z weighing function in order to obtain the rms value in the time domain. In the present paper, we have applied Tustin's approximation to transform the Laplace weighing function to the z weighing and validated this method by reviewing the various cases.

• The Transactions of the Korean Institute of Power Electronics
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• v.12 no.4
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• pp.332-338
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• 2007

In this paper, the three modified space vector modulation methods are suggested in order to control effectively the shoot-through time at Z-source inverter. Both the switching patterns of three modulation methods and the modulation signals with a variation of shoot-through time are analyzed. The optimum modified space vector modulation method is determined by both the control range of the shoot-through time and the symmetry of the switching pattern and modulation signal. The performances of modulation methods are verified with the simulation results with 32-bit DSP.

• Journal of the Semiconductor & Display Technology
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• v.20 no.4
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• pp.119-124
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• 2021

In a situation where Moore's law, which states that the performance of semiconductor integrated circuits doubles every two years, is showing a limit from a certain point, and it is difficult to increase the performance due to the limitations of exposure technology.In this study, a wafer hybrid method that can increase the degree of integration Various research on bonding technology is currently in progress. In this study, in order to achieve rotational precision between wafers in wafer hybrid bonding technology, modeling of θ_z alignment stage and VCM actuator modeling used for rotational alignment, magnetic field analysis and desgin, control, and evaluation are performed. The system of this study was controlled by VCM actuator, capactive sensor, and dspace, and the working range was ±7200 arcsec, and the in-position and resoultion were ±0.01 arcsec. The results of this study confirmed that safety and precise control are possible, and it is expected to be applied to the process to increase the integration.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.22 no.2
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• pp.22-30
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• 1986

It is very important for a navigator on bridge to know the maneuverability of his ship sufficiently at sea. Generally, the data of a turning circle test have long been used to study and evaluate the maneuverability of a ship. But referring only the data of the turning circle test method, he can not evaluate his ship's maneuvering characteristics sufficiently. So nowaday the test method added Z test to turning circle test for more detail references is considered to be desirable. In this paper, the authors performed PAL test and Z test together in order to study the maneuverability of M. S.Pusan 403, training ship of the National Fisheries University of Pusan. According to the results of PAL test, the rudder effect in port rudder angle of the M. S. Pusan 403 was found to be more effective than that in starboard one, because her changing amounts of angular velocity, turning radius and tangent speed in port rudder angles were found to be larger than those of them in starboard rudder one in unsymmetry. The relation between her drift angle(.8) and rudder angle (0) was found to be changing with .8=0.640 in direct proportion. As it appeared that her calculated K'-values were smaller than the standard K'-values of different kinds of ships in accordance with her Z test, her turning ability was found to be lower. The running distance of a turn in her 10$^{\circ}$ Z test was about 8.3 times her own length and was found not to be exceeded the standard maneuvering distance, therefore she was considered to have good maneuverabilities synthetically.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.3
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• pp.355-364
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• 2013

Respect to the input AC voltage and output DC voltage, conventional three-phase PWM rectifier is classified as the voltage type rectifier with boost capability and the current type rectifier voltage with buck capability. Conventional PWM rectifier can not at the same time the boost and buck capability and its bridge is weak in the shoot- through state. These problems can be solved by Z-source PWM rectifier which has all characteristic of voltage and current type PWM rectifier. By shoot-through duty ratio control, the Z-source PWM rectifier can buck and boost at the same time, also, there is no need to consider the dead time. This paper proposes the input AC voltage sensorless control method of a three-phase Z-source PWM rectifier in order to accomplish the unity input power factor and output DC voltage control. The proposed method is estimated the input AC voltage by using input AC current and output DC voltage, hence, the sensor for the input AC voltage detection is no needed. comparison of the estimated and detected input AC voltage, estimated phase angle of the input voltage, the output DC voltage response for reference value, unity power factor, FFT(Fast Fourier Transform) of the estimated voltage and efficiency are verified by PSIM simulation.

• Women's Health Nursing
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• v.9 no.2
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• pp.152-160
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• 2003

The purpose of this study is to determine the effect of a health management program on body composition(body weight, body fat mass, body fat ratio, lean body mass, abdominal fat ratio), self-efficacy and health promotion behavior in middle-aged women. This 6-week long program containing exercise and health education was developed by researchers. The study design was one group pretest-posttest design. Data for the study was collected from August 1 to September 15, 2002. The participants consisted of 15 middle - aged women living in the community. The collected data was analyzed using Wilcoxon Matched - Signed - Ranks Test by SPSS/WIN program The results are as follows : 1. There was a significant difference in body composition at week 6 compared to week 1. The body weight, body fat mass and body fat ratio significantly decreased(Z= -2.533, p=. 011 ; Z= -2.023, p= .043; Z= -2.023, p= .043). But the lean body mass significantly increased(Z= -2.226, p= .026). 2.There was a significant improvement in self-efficacy at week 6 compared to week 1(Z= -3.434, p= .001). 3.There was a significant improvement in health promotion behavior at week 6 compared to week 1(Z = -3.305, p= .001). In conclusion, health management program promoting self - efficacy for middle-aged women was effective in improving health promotion behavior. Further study with a longer follow up period is necessary in order to test the long term effect of the program.

• The Transactions of the Korean Institute of Power Electronics
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• v.13 no.1
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• pp.41-45
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• 2008

This paper deals with the estimation method on the initial pole position of a z-axis permanent magnet linear synchronous motor(PMLSM) without magnetic pole sensors such as Hall sensors. The proposed method takes account of the gravitational force at z-axis and also the load conditions. The algorithm consists of two steps. The first step is to approximately estimate the initial q-axis by monitoring the movements due to the test current at predefined different test q-axes. The second step is to estimate the real q-axis as accurately as possible by using the outputs corresponding to torques due to the test current at three different test q-axes in order to avoid the effect of load mass variations. Experimental results on the z-axis PMLSM show good estimation characteristics of the proposed method irrespective of load mass conditions.

• Journal of dental hygiene science
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• v.13 no.3
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• pp.330-338
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• 2013

In order to explore microleakage in class V cavity based on different kinds of several dentin adhesive and composite resin, 2 kinds of composite resin was restored and exposed after applying 4 kinds of dentin adhesives. Deposited in methylene blue solution for 4 hours and cut in parallel with tooth longitudinal axis. By observing dye penetration level of enamel and dentin margins of each restored resin following conclusion was obtained. 1. In composite resin Filtek Z350XT Universal (3M/ESPE Dental Products, USA) in enamel margin, Easy Bond (3M/ESPE Dental Products) showed the lowest microleakage and this leakage was represented to be high in the order of Single Bond 2 (3M/ESPE Dental Products), Scotchbond Multi-Purpose (3M/ESPE Dental Products) and Cearfil SE Bond (Kuraray Medical Inc., Japan). In case of Filtek Z350XT Flowable (3M/ESPE Dental Products), Scotchbond Multi-Purpose showed the lowest microleakage and this leakage was represented to be high in the order of Single Bond 2, Clearfil SE Bond and Easy Bond. 2. In case of Filtek Z350XT Universal in dentin margin, Easy Bond showed the lowest microleakage and this leakage was represented to be high in the order of Scotchbond Multi-Purpose, Single Bond 2 and Clearfil SE Bond. In case of Filtek Z350XT Flowable, Scotchbond Multi-Purpose and Single Bond showed the lowest microleakage and this leakage was represented to be high in the order of Clearfil SE Bond and Easy Bond. 3. In all the groups excepting S-U group (Single Bond 2+Filtek Z350XT Universal), enamel margin showed more higher microleakage than that of dentin margin. 4. There was a difference between enamel and dentin margin among each group but it was not significant statistically (p>0.05). When summarizing this result, it is considered that composite resin and dentin adhesive could be applied selectively and particularly in case of applying 1-step self-etching dentin adhesive, this method would be advantageous for manipulation convenience and shortening of operation time.

• Journal of the korean academy of Pediatric Dentistry
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• v.43 no.4
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• pp.427-434
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• 2016

The aim of this study was to compare the mechanical properties of high viscosity bulk-fill resin composites, $Filtek^{TM}$ Bulk Fill Posterior Restorative (FBF) and $Tetric^{(R)}$ N-Ceram Bulk Fill (TBF), with conventional composite ($Filtek^{TM}$ Z-350 XT, Z-350). The Vickers hardness test which indicates the degree of conversion was performed and the dye penetration test was performed to measure the microleakage which indicates polymerization shrinkage amount. To minimize experimental error, the standardized 3D-printed molds and the bovine teeth were used. Obtained data were analyzed by the Kruskal-Wallis test and Mann-Whitney test with the confidence interval of 95%. In the microhardness test within 1 hour of polymerization, lower surface of FBF and TBF showed significantly lower value than that of Z-350 (p < 0.05). But after 24 hours, the microhardness of FBF had increased and showed no significant difference with Z-350 (p > 0.05). In top and 2 mm depth surface, mean microhardness values were in the following order: Z-350 > FBF > TBF (p < 0.05). The mean microleakage value of TBF was significantly lower than others (p < 0.05). For clinical application of bulk-fill resin composites, caution for applying masticatory forces during 24 hours after polymerization is advised and further studies to decrease microleakage should be conducted.

• The Journal of Korean Academy of Sensory Integration
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• v.7 no.1
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• pp.1-12
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• 2009

Objective : This study is to verify effect of a sensory integration (SI) intervention on sensory processing of children with sensory modulation disorder (SMD), and to explore how the SI intervention affect play, socialization, occupational performance and occupational satisfaction of those children. Method : Five children with developmental disabilities living in metropolitan were diagnosed as SMD by the Sensory History Interview (SHI) and Short Sensory Profile (SSP). The SMD children undergone the 48 sessions of 50 min intervention twice in a week for six months and took the Revised Knox Preschool Play Scale(RKPPS), Social maturity test, Canadian Occupational Performance Measure(COPM), and Japanese Sensory Inventory Revised(JSI-2) before- and after the intervention. The result data analyzed by the Wilcoxon matched-pair signed rank test. Results : All data of post-intervention differed significantly; RKPPS(Z=-2.023, p=.043), Social maturity test(Z=-2.023, p=.043); occupational performance(Z=-2.023, p=.043); satisfaction(Z=-2.032, p=.042); and tactile system of JSI-2(Z=-2.032, p=.042). Conclusions : The results advocate that sensory integration intervention is effective in improving tactile processing, play, socialization, occupational performance, and occupational satisfaction of child with SMD. It is found that sensory integration intervention improves not only one's occupational performance but also underlying components of the performance. In order to generalize this conclusion, further studies need to be done with more number of subjects and consideration of environmental factors. Striving for more reliable and valid methods of data collection is also suggested.