• Smart Structures and Systems
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• v.23 no.3
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• pp.295-306
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• 2019

Shanghai Tower is a 632-meter super high-rise building located in an area with wind and active earthquake. A sophisticated structural health monitoring (SHM) system consisting of more than 400 sensors has been built to carry out a long-term monitoring for its operational safety. In this paper, a reduced-order model including 31 elements was generated from a full model of this super tall building. An iterative regularized matrix method was proposed to tune the system parameters, making the dynamic characteristic of the reduced-order model be consistent with those in the full model. The updating reduced-order model can be regarded as a benchmark model for further analysis. A long-term monitoring for structural dynamic characteristics of Shanghai Tower under different construction stages was also investigated. The identified results, including natural frequency and damping ratio, were discussed. Based on the data collected from the SHM system, the dynamic characteristics of the whole structure was investigated. Compared with the result of the finite element model, a good agreement can be observed. The result provides a valuable reference for examining the evolution of future dynamic characteristics of this super tall building.

• Journal of the Korean Society of Clothing and Textiles
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• v.47 no.1
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• pp.73-84
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• 2023

This study aims to identify the current sizing communication issues of menswear on retail websites and to suggest an effective size information presentation method. Based on sales frequency and awareness in the Korean menswear market, 22 brand websites were selected, and size-related information was investigated using 7 types of representative apparel items. The current diverse types of size codes had limitations in delivering actual product size information. Many websites preferred to display garment dimensions rather than basic body measurements, which is the suggested size designation method in Korean Standard. The websites posted fit model photos and customer reviews. However, the body size specifications, which consumers can use as a useful reference, were often omitted. There was also a high uncertainty in product size selection, with only the basic body measurement information listed, and there was a high deviation of garment dimensions within the same basic body measurements. The product size distribution did not match actual Korean body types. Based on the findings, we suggested improved effective sizing communication methods. These methods will contribute to a better online shopping environment for both consumers and retail sellers.

• Nuclear Engineering and Technology
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• v.55 no.3
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• pp.947-957
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• 2023

Curved cylindrical structures such as elbows have a non-uniform thickness distribution due to their fabrication process, and as a result have a number of complex mode shapes, including circumferential and axial nodal patterns. In nuclear power plants, material degradation is induced in pipes by flow accelerated erosion and corrosion, causing the wall thickness of carbon steel elbows to gradually thin. The corresponding frequencies of each mode shape vary according to the wall thinning state. Therefore, the thinning state can be estimated by monitoring the varying modal characteristics of the elbow. This study investigated the varying modal characteristics of artificially thinned carbon steel elbows for each thinning state using numerical simulation and experimental methods (MRIT, Multiple Reference Impact Test). The natural frequencies of specified mode shapes were extracted, and results confirmed they linearly decreased with increasing thinning. In addition, by comparing single FRF (Frequency Response Function) data with the results of MRIT, a concise and cost effective thinning estimation method was suggested.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.40 no.3
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• pp.172-180
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• 2003

The purpose of this study is to observe the heat transfer process in in-vivo human muscle based on Proton Resonance Frequency(PRF) method in Magnetic Resonance Imaging(MRI). MRI was obtained to measure the temperature variation according to the heat transfer in phantom and in-vivo human calf muscle. A phantom(2% agarose gel) was used in this experiment. MR temperature measurement was compared with the direct temperature measurement using a T-type thermocouple. After heating agarose gel to more than 5$0^{\circ}C$ in boiling hot water, raw data were acquired every 3 minutes during one hour cooling period for a phantom case. For human study heat was forced to deliver into volunteer's calf muscle using hot pack. Reference data were once acquired before a hot pack emits heat and raw data were acquired every 2 minutes during 30minutes. Acquired raw data were reconstructed to phase-difference images with reference image to observe the temperature change. Phase-difference of the phantom was linearly proportional to the temperature change in the range of 34.2$^{\circ}C$ and 50.2$^{\circ}C$. Temperature resolution was 0.0457 radian /$^{\circ}C$(0.0038 ppm/$^{\circ}C$) in phantom case. In vivo-case, mean phase-difference in near region from the hot pack is smaller than that in far region. Different temperature distribution was observed in proportion to a distance from heat source.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.7
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• pp.76-84
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• 2013

In the passive emitter localization using instantaneous TDOA (time difference of arrival) and FDOA (frequency difference of arrival) measurements, the estimation accuracy can be improved by collecting additional measurements. To achieve this goal, it is required to increase the number of the sensors. However, in electronic warfare environment, a large number of sensors cause the loss of military strength due to high probability of intercept. Also, the additional processes should be considered such as the data link and the clock synchronization between the sensors. Hence, in this paper, the passive localization of a stationary emitter is presented by using the successive TDOA and FDOA measurements from two moving sensors. In this case, since an independent pair of sensors is added in the data set at every instant of measurement, each pair of sensors does not share the common reference sensor. Therefore, the QCLS (quadratic correction least squares) methods cannot be applied, in which all pairs of sensor should include the common reference sensor. For this reason, a Gauss-Newton algorithm is adopted to solve the non-linear least square problem. In addition, to show the performance of the proposed method, we compare the RMSE (root mean square error) of the estimates with CRLB (Cramer-Rao lower bound) and derived the CEP (circular error probable) planes to analyze the expected estimation performance on the 2-dimensional space.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.5 s.122
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• pp.437-447
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• 2007

A series of research to seek for the relationship between subjective responses and noise level for transportation noise have been proceeded, and their results showed similar for some cases and different for some other cases as well, which is considered due to the various conditions such as the way of survey, different scale applied, and country etc. This study aimed to analyze the relationship between sound level and subjective response for the different kinds of transportation noise. The noises recorded in real situation were played to thirty subjects with fourty nine adjectives. The percentage of people annoyed(% PA) and the percentage of people highly annoyed(% HA) were calculated from the subjective results and compared how many percent of people are annoyed and highly annoyed for the same sound level. As a result of calculating the average, the aircraft noise was highest and the white noise lowest. The relationship between window TL and average point was well correlated except the aircraft noise which was scattered because of high sound level at specific frequency and low TL at corresponding frequency. This means that appropriate rating method for airborne sound transmission should be sought for to evaluate outdoor noise which has different frequency characteristics. The Boltzmann equation for % PA and % HA was applied to predict the sound level corresponding to the percentage. It is concluded that the aircraft noise and road traffic noise have almost same response and the railway noise was same with white noise, used for the reference noise, annoyed lower than other noises about by 3 dB.

• Aerospace Engineering and Technology
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• v.6 no.2
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• pp.79-86
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• 2007

In order to operate Low Earth Orbit(LEO) satellite on space, technical requirements and administrative procedure which are defined by the International Telecommunication Union(ITU) should be followed on satellite development. Main technical requirements to follow are purpose of use, bandwidth, Radio Frequency(RF) intensity, and constraints on new satellite network about existing satellite networks according to frequency spectrum. Such ITU's requirements are reflected and designed on system specification and space to ground interface control document. In order to have a right and protection about using the satellite network on space, the satellite network has to be registered on Master International Frequency Register(MIFR) and procedure for this has to be followed. Coordination with countries raising objection is needed in order to register. And reference and method for coordination are also needed.

• Korea Journal of Hospital Management
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• v.22 no.4
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• pp.50-60
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• 2017

Purposes: The purpose of this study was to identify the preferred types of the hospital reservation cancellation management to help reduce the reservation cancellations. Methodology: This study sampled 327 outpatients or their guardians who had reserved a university hospital and a general hospital located in the southwestern part of Seoul, and the responses from 300 of them were used for the final analysis. The subjects' preferences of reservation cancellation management types were analyzed in reference to their demographic variables. The timing and frequency of pre-notification preferred by the subjects were examined. A multidimensional scaling methods and correspondence analysis was used to identify preference for management methods of no-show and type of reservation guide. Findings: As a result, 77.3% of the respondents were perceived that the reservation cancellation was a habit. The most preferred method of managing the reservation cancellation would be refusal to refund the reservation deposit (61.7%), followed by payment for cancellation (16.0%), limit of future reservations (16.0%) and penalty (6.3%) in their order. 186 of the subjects (62.0%) preferred the texting for prevention of reservation cancellations, and 102 of the subjects (34.0%) preferred the phone calls. The preferred timing and frequency of the SMS were twice 3 days before, once a day before and three times 7 days before, while the preferred timing and frequency of phone call was once a day before. Practical Implications: The no-show rate can be improved by enhancing SMS pre-notification and by improving afterwards telephone counseling. For other factors, it needs to study on the service differentiation with the characteristics of each patient group.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.6
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• pp.675-681
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• 2019

Noise removal is a pre-requisite procedure in image processing, and various methods have been studied depending on the type of noise and the environment of the image. However, for image processing with high-frequency components, conventional additive white Gaussian noise (AWGN) removal techniques are rather lacking in performance because of the blurring phenomenon induced thereby. In this paper, we propose an algorithm to minimize the blurring in AWGN removal processes. The proposed algorithm sets the high-frequency and the low-frequency component filters, respectively, depending on the pixel properties in the mask, consequently calculating the output of each filter with the addition or subtraction of the input image to the reference. The final output image is obtained by adding the weighted data calculated using the standard deviations and the Gaussian distribution with the output of the two filters. The proposed algorithm shows improved AWGN removal performance compared to the existing method, which was verified by simulation.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.7 no.3
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• pp.27-33
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• 1993

This paper presents the &tal controller for driving high frequency voltage fed PWM inverter that carrier frequency is over 2OkHz.We analyzed the conventional PWM to select a proper PWM pattern. as the result, obtained PWM pattern of the controller in which asynchronus staircase sinusoidal waveform is used as reference signal, and variable carrier ratio method was used for PWM control. The PWM controller is designed by fully digital method. Especially, Thk proposed controller is consisted of 8 bit one-chip microprocessor and digital logic. the former is for arithmetic and data processing, and the latter is for PWM pattern synthesis. Therefore, The responsibility and controllability is improved. Also, Data processing capability is improved using proper program to output modulation index with 9 bits. Circuits configuration of digital controller are made up of one chip 8051 and EPLD, and its controllability is tested by operating voltage fed inverter. Harmonics and current waveform is evaluated and analyzed for the voltage fed inverter system.