• Journal of Mechanical Science and Technology
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• v.16 no.10
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• pp.1187-1200
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• 2002

This paper is concerned with the design or an LMI (Linear Matrix Inequality) -based H$\infty$ controller for a line of sight (LOS) stabilization system and with its robustness performance. The linearization of the system is necessary to analyze various nonlinear characteristics, but the linearization entails modeling uncertainties which reduce its performance. In addition, the stability of the LOS can be adversely affected by angular velocity disturbances while the vehicle is moving. As the vehicle accelerates, all the factors that are Ignored and simplified for the linearization tend to Inhibit the performance of the system. The robustness in the face of these uncertainties needs to be assured. This paper employs H$\infty$ control theory to address these problems and the LMI method to provide a suitable controller with minimal constraints for the system. Even though the system matrix does not have a full rank, the proposed method makes it possible to design a H$\infty$ controller and to deal with R and S matrices for reducing the system order. It can be also shown that the proposed robust controller has a better disturbance attenuation and tracking performance. The LMI method is also used to enhance the applicability of the proposed reduced-order H$\infty$ controller for the system given. The LMI-based H$\infty$ controller has superior disturbance attenuation and reference input tracking performance, compared with that of the conventional controller under real disturbances.

• Journal of the Korean Home Economics Association
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• v.25 no.3
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• pp.15-26
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• 1987

The purpose of this study was to develop the pattern drafting method which would be suitable to their physical characteristics for the fatty body of 40∼55 aged Korean women who are more than 1.5 Rohrer's Index and 90㎝ bust girth. The study was composed as follows; 1. Body measurement and statistical analysis: One hundred and thirty women were measured on 29 items. Thirty-four items including 29 measured items and 5 calcutated items were analyzed statistically. 1) Mean, standard deviation, variance, maximum, minimum, range were computed. 2) Correlation coefficients between each items were computed. 2. Development of new bodice pattern drafting method: Measurement items necessary to draft new bodice pattern were bust girth, center back waist length, shoulder width, back width, chest and neck base girth. The new pattern was examined through three wearing tests for completion. 3. Evaluation of the new pattern drafting method: The new pattern was objectively evaluated by the sensory test. The sensory evaluation was applied to evaluate the new pattern for the fatty body women by comparint it with the conventional patterns. The results of sensory tests of the new pattern are as follows: 1) The composite reliability coefficient is 0.7698, and the reliability of sensory test shows high. 2) According to a statistical analysis of the result of the 23 items on the questionaire, all the items showed significant differences(α 0.01) between the two, with the new pattern having higher scores. The new pattern is better conventional pattern as the average mark of the former is 3.901 but that of latter is 2.926. The new pattern drafting method proved to be superior to the conventional one especially in the fitness at the center front neck point, shoulder point, side line, armscye depth, position of bust point, chest width line, under arm dart and the shoulder line.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.2
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• pp.164-171
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• 2004

Active control techniques have been used in wide areas of noise and nitration control engineering and a noise barrier is one of them. Omoto's work in 1993 would be one of the fundamental and systematic studies on the actively controlled noise barrier, in which he used equal number of control sources and error sensors. The error sensors were placed uniformly along the top edge of the noise barrier with equal distance apart and the control sources were placed in the exactly same way some distance apart from the error sensors. Since then, a couple of studies were made on the secondary sources'arrangement rather than the optimality of secondary source positions. Shao's results showed that arc shaped arrangement for secondary sources is better than the straight line one, and later work of Yang showed that the more important factor is the average distance between the primary source and secondary sources. However, since these studies were all executed with a simple uniform distribution of the secondary sources along the straight line or arc, it is difficult to conclude which arrangement is superior In order for the fare comparison. the optimality of the source positions in each arrangement must be given in prior. The primary goal of this study is focused on this aspect and some major factors were investigated and compared. The computer simulation results showed that the arc shaped arrangement is marginally better than the straight line one, and more importantly slightly tuned position can greatly improve the performance of the control system.

• The Journal of Advanced Prosthodontics
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• v.9 no.4
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• pp.302-307
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• 2017

PURPOSE. This study compared the SCGAs measured in three types of radiographic images (panoramic, CBCT panoramic-section, and CBCT cross-section images) with values measured using the protrusive occlusal record. MATERIALS AND METHODS. SCGAs were measured in 20 patients on a semi-adjustable articulator using the protrusive interocclusal record. Panoramic and CBCT images were obtained. SCGAs were measured on CBCT images in panoramic and cross sections. In all of the radiographic images, SCGAs were measured using the Frankfort horizontal reference line and the mean curvature line. The most-superior and most-inferior points of the curvatures were identified to determine the mean curvature line. Each measurement was performed twice by two operators independently. The data were analyzed by the t-test, Pearson's correlation test, and Cronbach's ${\alpha}$ using SPSS (${\alpha}=.05$). RESULTS. The mean right and left SCGAs were as follows: protrusive occlusal record (30.1 and 30.2 degrees, respectively), panoramic (38.9 and 38.7 degrees), CBCT panoramic sections (35.4 and 36.8 degrees), and CBCT cross sections (35.3 and 36.1 degrees). The SCGAs differed significantly among the groups. The Pearson coefficients for the correlations with the protrusive occlusal record measurements on the left and right sides were as follows: panoramic (0.834 and 0.791, respectively), CBCT panoramic-section (0.918 and 0.837), and CBCT cross-section (0.918 and 0.845) images. CONCLUSION. Strong correlations were found between SCGAs obtained using radiographic images and the protrusive occlusal record.

• Computers and Concrete
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• v.20 no.5
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• pp.563-572
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• 2017

Ordinary reinforced concrete (RC) and prestressed concrete bridges are two popular and typical types of short- and medium-span bridges that accounts for the vast majority of all existing bridges. The cost of maintaining, repairing or replacing degraded existing RC bridges is immense. Detecting the abnormality of RC bridges at an early stage and taking the protective measures in advance are effective ways to improve maintenance practices and reduce the maintenance cost. This study proposes a systematic method from influence line (IL) identification to damage detection with applications to RC bridges. An IL identification method which integrates the cubic B-spline function with Tikhonov regularization is first proposed based on the vehicle information and the corresponding moving vehicle induced bridge response time history. Subsequently, IL change is defined as a damage index for bridge damage detection, and information fusion technique that synthesizes ILs of multiple locations/sensors is used to improve the efficiency and accuracy of damage localization. Finally, the feasibility of the proposed systematic method is verified through experimental tests on a three-span continuous RC beam. The comparison suggests that the identified ILs can well match with the baseline ILs, and it demonstrates that the proposed IL identification method has a high accuracy and a great potential in engineering applications. Results in this case indicate that deflection ILs are superior than strain ILs for damage detection of RC beams, and the performance of damage localization can be significantly improved with the information fusion of multiple ILs.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.25 no.1
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• pp.39-49
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• 1995

This study was performed to determine the each location of lesions in the maxillary sinus and to evaluate the relationship between the floor of the antrum and the apical regions of teeth by the comparison of the panoramic view and panoramic sinus view. For this study, experimentally with two dry skulls, jelly balls of 8mm and 15mm in diameter containing a short wire for the radiopacity similar to the cyst and clinically 5 patients having mucosal cyst in the antrum and 10 patients having periapical lesion of molar were used. The experimental cystic lesions were simulated with jelly ball being attached in turn to each wall of the antrum. The radiolucent periapical lesions of upper molars were formed by using round bur and the radiopaque periapical lesions were simulated by filling the former lesions with lead foil. Each panoramic view and each panoramic sinus view of the experimental lesions and patients were obtained by using panoramic machine and analyzed. The obtained results were as follows : 1. On the panoramic sinus view, the innominate line was approximately coincided with the most lateral portion of the antrum and the posterior wall appeared as the narrow area at the mesial side of the innominate line. The anterior wall occupied totally the mesial side of the innominate line, and the medial wall occupied the mesial half of the antrum. 2. In all cases of experimental cystic lesion attached to each wall of the antrum, the location of each lesion was able to be determined by applying Tube shift technic. 3. The palatal root and mesiobuccal root of the molar appeared as being transposed each other mesiolaterally on the panoramic and panoramic sinus views. 4. The panoramic sinus view was superior to the panoramic view in revealing the relationship between the floor of the antrum and the periapical lesion.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.11a
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• pp.35-38
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• 2002

In this paper, the characteristics of channel hot electron (CHE) injection for the write operation in a NOR-type SONOS flash memory with common source line were investigated. The thicknesses of he tunnel oxide, the memory nitride， and the blocking oxide layers for the gate insulator of the fabricated SONOS devices were $34{\AA}$, $73{\AA}$, and $34{\AA}$, respectively. The SONOS devices compared to floating gate devices have many advantages, which are a simpler cell structure, compatibility with conventional logic CMOS process and a superior scalability. For these reasons, the introduction of SONOS device has stimulated. In the conventional SONOS devices, Modified Folwer-Nordheim (MFN) tunneling and CHE injection for writing require high voltages, which are typically in the range of 9 V to 15 V. However CHE injection in our devices was achieved with the single power supply of 5 V. To demonstrate CHE injection, substrate current (Isub) and one-shot programming curve were investigated. The memory window of about 3.2 V and the write speed of $100{\mu}s$ were obtained. Also, the disturbance and drain turn-on leakage during CHE injection were not affected in the SONOS array. These results show that CHE injection can be achieved with a low voltage and single power supply, and applied for the high speed program of the SONOS memory devices.

• Journal of the Korean Institute of Telematics and Electronics
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• v.27 no.2
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• pp.16-30
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• 1990

The microwave imaging technique which is mostly analyzed in the spectral domain has been exploited the image reconstruction of object using the 2-dimensional inverse Fourier transform so far. In this paper, a new method of microwave imaging corresponding to a coherent tomographic scheme in the space domain is presented for the conducting objects. Also, it is shown that image reconstruction for lines targets and conducting circular cylinder is per-formed by computer simulation using the filtered-backprojection which is the reconstruction algorithm widely used in X-ray CT. The proposed method analyzed in the space domain can reconstruct the image without any problems such as interpolation and image artifact which results from the reconstruction in the spectral domain for the symmetric conducting objects located in the origin. The image reconstructed by the filtered-backprojection in the space domain has given the superior quality compared with that produced by 2-dimensional IFFT using the interpolation scheme in the spectral domain. Finally, the image of line targets using the moment-method in the space domain which does not require the wide-band signal as the spectral domain has shown a possibility of super-resolution in the microwave imaging.

• Journal of the Korean Magnetics Society
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• v.9 no.1
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• pp.55-63
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• 1999

It is necessary to eliminate the broad band noise whose frequency is in the range of several kHz to tens MHz generated from the AC power line to supply the power to electrical and electronic equipments. Because this kind of noise could damage or malfunction such equipments. To suppress those noises, some conventional devices such as a filter or surge suppressor have been used. However, they can not be isolated from the common-mode noise widely spreaded in all power line, which results in poor common-mode rejection performance. In this paper, we proposed a design method of shielded isolation transformer and a jumped circuit analysis model for shielded isolation transformer applicable to filtering common-mode noise as well as normal-mode noise. The analysis model has been verified as a suitable one for shielded isolation transformer through comparison of the simulation with experiment. In addition, it has been shown that the reduction performance for conducted noise of prototype 3 kVA shielded isolation transformer is superior to a unshielded isolation transformer.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.17 no.9
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• pp.972-981
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• 1992

In this paper, the performance of linear and hard-limiting correlation receivers for DS/SSMA BPSK power line communication system is analyzed. Strong impulsive noise of power line is modeled with Chan's noise model, and the performance of both receivers is analyzed in terms of parameters such as ratio of power spectrum density of impulsive noise to that background noise, ratio in impulsive noise width th that of data bit, and interarrival time of impulsive noise. And also multiple access capacity is evaluated with Gaussian approximation of multiple access interference. The results of this analysis reveal that the performance of linear correlation receiver is superior to that of hard-limiting correlation receiver when $N_1/N_b$ is small and is close to 1. But the BER and the multiple access capacity of hard-limiting correlation receiver becomes better in comparison with linear correlation receiver as $N_1/N_b$ increases.