• Wind and Structures
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• v.29 no.3
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• pp.163-175
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• 2019

Multispan suspension bridges make a good alternative to single-span ones if the crossed strait or river width exceeds 2-3 km. However, multispan three-tower suspension bridges are found to be very sensitive to the wind load due to the lack of effective longitudinal constraint at their central tower. Moreover, at certain critical wind speed values, the aerostatic instability with sharply deteriorating dynamic characteristics may occur with catastrophic consequences. An attempt of an in-depth study on the aerostatic stability mode and damage mechanism of three-tower suspension bridges is made in this paper based on the assessment of strain energy and dynamic characteristics of three particular three-tower suspension bridges in China under different wind speeds and their further integration into the aerostatic stability analysis. The results obtained on the three bridges under study strongly suggest that their aerostatic instability mode is controlled by the coupled action of the anti-symmetric torsion and vertical bending of the two main-spans' deck, together with the longitudinal bending of the towers, which can be regarded as the first-order torsion vibration mode coupled with the first-order vertical bending vibration mode. The growth rates of the torsional and vertical bending strain energy of the deck after the aerostatic instability are higher than those of the lateral bending. The bending and torsion frequencies decrease rapidly when the wind speed approaches the critical value, while the frequencies of the anti-symmetric vibration modes drop more sharply than those of the symmetric ones. The obtained dependences between the critical wind speed, strain energy, and dynamic characteristics of the bridge components under the aerostatic instability modes are considered instrumental in strength and integrity calculation of three-tower suspension bridges.

• Nuclear Engineering and Technology
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• v.18 no.3
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• pp.209-217
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• 1986

The inlet coolant temperature reduction technique has been used to extend the load follow operation further in the end-of-cycle-life(EOL). In order to simulate the technique and calculate the nuclear characteristics of a PWR core according to the load follow operation, the three dimensional computing system has been established. The analysis was performed in both MINB and SPINR modes of typical 12-3-6-3 locad follow operation for the EOL of KNU-1 plant. Moreover, the capability of return-to-power has been also tested for those two modes with the system analysis by the RETRAN-02 code. The results show that it has no difficulty to extend the load follow operation further in the EOL by applying the inlet coolant temprature reduction, and also the spinning reserve capacity(SRC) increases by 13% in MINB mode and 14% in SPINR mode Bore that used by control rods only, for 14$^{\circ}$ F drop in the inlet temperature.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.4
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• pp.59-64
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• 2023

In this paper, It is proposed through the empirical design of a Conducted EMI filter for noise reduction of power used in electronic devices. For the proposed structure, A-type, B-type, C-type, and D-type structures were designed, and conductive noise reduction was confirmed by using an LC network with various X-capacitors, Y-capacitors, and Air-inductors. 10 [μH] was used for L1 and L2, and 4.7 [nF] was used for C1 and C2. L3 for common mode used 13[μH], and C5, C6, C7 were designed using 10[nF]. The measured insertion loss values of the designed EMI filter were -74.4[dB] at 3.2MHz, -75.4[dB] at 4MHz, and -75.3[dB] at 13.56MHz. Therefore, the proposed EMI filter will be able to reduce power supply noise used in various electronic devices.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.45 no.6
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• pp.95-107
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• 2008

In this paper, we propose a fast mode decision method for temporal and spatial scalability to reduce computational complexity of mode decision that used to be computationally one of the most intensive processes of the MPEG-4 AVC|H.264 SE(Scalable Extension) encoding. For temporal scalability, we propose an early skip method and MHM(mode history map) method. The early skip method confines macroblock modes of backward and forward frames within selected a few candidates. The MHM method utilizes stored information of frames inside a GOP of lower levels for the decision of MHM at higher level. For the spatial scalability, we propose the method that uses a candidate mode according to the MHM method and adds the BL_mode as candidates. The proposed scheme reduces the number of candidate modes to reduce computational complexity in mode decision. The proposed scheme reduces total encoding time by about 52% for temporal scalability and 47% for spatial scalability without significant loss of RD performance.

• Korean Journal of Radiology
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• v.22 no.11
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• pp.1777-1785
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• 2021

Objective: To investigate the accuracy of the Agatston score obtained with the ultra-high-pitch (UHP) acquisition mode using tin-filter spectral shaping (Sn150 kVp) and a kVp-independent reconstruction algorithm to reduce the radiation dose. Materials and Methods: This prospective study included 114 patients (mean ± standard deviation, 60.3 ± 9.8 years; 74 male) who underwent a standard 120 kVp scan and an additional UHP Sn150 kVp scan for coronary artery calcification scoring (CACS). These two datasets were reconstructed using a standard reconstruction algorithm (120 kVp + Qr36d, protocol A; Sn150 kVp + Qr36d, protocol B). In addition, the Sn150 kVp dataset was reconstructed using a kVp-independent reconstruction algorithm (Sn150 kVp + Sa36d, protocol C). The Agatston scores for protocols A and B, as well as protocols A and C, were compared. The agreement between the scores was assessed using the intraclass correlation coefficient (ICC) and the Bland-Altman plot. The radiation doses for the 120 kVp and UHP Sn150 kVp acquisition modes were also compared. Results: No significant difference was observed in the Agatston score for protocols A (median, 63.05; interquartile range [IQR], 0-232.28) and C (median, 60.25; IQR, 0-195.20) (p = 0.060). The mean difference in the Agatston score for protocols A and C was relatively small (-7.82) and with the limits of agreement from -65.20 to 49.56 (ICC = 0.997). The Agatston score for protocol B (median, 34.85; IQR, 0-120.73) was significantly underestimated compared with that for protocol A (p < 0.001). The UHP Sn150 kVp mode facilitated an effective radiation dose reduction by approximately 30% (0.58 vs. 0.82 mSv, p < 0.001) from that associated with the standard 120 kVp mode. Conclusion: The Agatston scores for CACS with the UHP Sn150 kVp mode with a kVp-independent reconstruction algorithm and the standard 120 kVp demonstrated excellent agreement with a small mean difference and narrow agreement limits. The UHP Sn150 kVp mode allowed a significant reduction in the radiation dose.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.23 no.1
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• pp.27-31
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• 2014

This paper describes a tomographic imaging technique for evaluating the thickness reduction of a plate-like structure using a noncontact sensor network based on an electromagnetic acoustic transducer that generates shear horizontal plate waves. Because this technique is based on the effect of mode cutoff and time of flight of guided waves caused by a change in thickness, the tomographic image provides information on the presence of defects in the structure. To verify the performance of the method, artificial defects with various thickness reduction ratios were machined in an aluminum plate, and the tomographic imaging results are reported. The results show that the generated tomographic image displays the thickness reductions and can identify their locations. Therefore, the proposed technique has good potential as a tool for health monitoring of the integrity of plate-like structures.

• Smart Media Journal
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• v.3 no.1
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• pp.39-45
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• 2014

The partial product matrix of a parallel squarer are symmetric about the diagonal. To reduce the number of partial product bits and the depth of partial product matrix, it can be typically folded, shifted and bit-rearranged. In this paper, an efficient design approach for the combined squarer, capable of operating on either unsigned or signed numbers based on a mode selection signal, is presented. By simulations, it is shown that the proposed combined squarers lead to up to 18% reduction in area, 11% reduction in propagation delay and 9% reduction in power consumption compared with the previous combined squarers.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.1
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• pp.201-204
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• 2011

For efficient noise reduction in a Fourier transform ion cyclotron resonance (FT-ICR) mass spectrum, a new algorithm was proposed. The suggested algorithm reduces white and electrical noise, and it improves signal-to-noise ratio. This algorithm has been optimized to reduce the noise more efficiently using the traces of signal level. The algorithm has been efficiently combined with derivative window to improve the resolution as well S/N. Time domain data was corrected for DC voltage interference. $t^n$ window was applied in time domain data to improved the resolution. However, $t^n$ window can improve the signal resolution, it will also increase the noise level in frequency domain. Therefore, newly developed noise reduction algorithm will be applied to make a balance between resolving power and S/N ratio for magnitude mode. The trace algorithm can determine the current data point with several data points (mean, past data, calculated past data). In the current calculations, we assumed data points with S/N ratio more than 3 were considered as signal data points. After the windowing and noise reduction, both resolution and signal-to-noise ratio were improved. This algorithm is applicable more efficiently to frequency dependent noise and large size data.

• The Korean Journal of Pain
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• v.24 no.4
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• pp.199-204
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• 2011

Background: Although many clinicians know about the reducing effects of the pulsed and low-dose modes for fluoroscopic radiation when performing interventional procedures, few studies have quantified the reduction of radiation-absorbed doses (RADs). The aim of this study is to compare how much the RADs from a fluoroscopy are reduced according to the C-arm fluoroscopic modes used. Methods: We measured the RADs in the C-arm fluoroscopic modes including 'conventional mode', 'pulsed mode', 'low-dose mode', and 'pulsed + low-dose mode'. Clinical imaging conditions were simulated using a lead apron instead of a patient. According to each mode, one experimenter radiographed the lead apron, which was on the table, consecutively 5 times on the AP views. We regarded this as one set and a total of 10 sets were done according to each mode. Cumulative exposure time, RADs, peak X-ray energy, and current, which were viewed on the monitor, were recorded. Results: Pulsed, low-dose, and pulsed + low-dose modes showed significantly decreased RADs by 32%, 57%, and 83% compared to the conventional mode. The mean cumulative exposure time was significantly lower in the pulsed and pulsed + low-dose modes than in the conventional mode. All modes had pretty much the same peak X-ray energy. The mean current was significantly lower in the low-dose and pulsed + low-dose modes than in the conventional mode. Conclusions: The use of the pulsed and low-dose modes together significantly reduced the RADs compared to the conventional mode. Therefore, the proper use of the fluoroscopy and its C-arm modes will reduce the radiation exposure of patients and clinicians.

• Journal of Advanced Navigation Technology
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• v.11 no.1
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• pp.9-16
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• 2007

In this paper, the Bit Error Ratio (BER) performances of the D8PSK modulation schemes for VDL Mode-2 are analyzed according to the matched and unmatched cases of the channel filters. The carrier frequency and phase offset effects are analyzed with unmatched case. Generally in digital transmission techniques, the Root Raised Cosine filters which are used as channel filters are applied to both sides at transmitter and receiver in order to achieve no ISI, but in VDL Mode-2, the Raised Cosine Filter is used only in transmission section and the receiver section uses general low pass filter, therefore we could not achieve ISI reduction effects but can have better spectrum quality. From the simulation results, the error probability is increased slightly (1~2dB) with use of un-matched channel filter, we got the conclusions that carrier phase offset do not effect to bit error ratio, but the frequency offset effect is so serious. Finally, narrow band D8PSK modulation signals are generated by the use of Digital Up-Converter and then its features are compared with analog modulator.