• Korean Journal of Radiology
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• v.24 no.7
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• pp.681-689
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• 2023

Objective: Three-dimensional rotational angiography (3D-RA) is increasingly used for the evaluation of intracranial aneurysms (IAs); however, radiation exposure to the lens is a concern. We investigated the effect of head off-centering by adjusting table height on the lens dose during 3D-RA and its feasibility in patient examination. Materials and Methods: The effect of head off-centering during 3D-RA on the lens radiation dose at various table heights was investigated using a RANDO head phantom (Alderson Research Labs). We prospectively enrolled 20 patients (58.0 ± 9.4 years) with IAs who were scheduled to undergo bilateral 3D-RA. In all patients' 3D-RA, the lens dose-reduction protocol involving elevation of the examination table was applied to one internal carotid artery, and the conventional protocol was applied to the other. The lens dose was measured using photoluminescent glass dosimeters (GD-352M, AGC Techno Glass Co., LTD), and radiation dose metrics were compared between the two protocols. Image quality was quantitatively analyzed using source images for image noise, signal-to-noise ratio, and contrast-to-noise ratio. Additionally, three reviewers qualitatively assessed the image quality using a five-point Likert scale. Results: The phantom study showed that the lens dose was reduced by an average of 38% per 1 cm increase in table height. In the patient study, the dose-reduction protocol (elevating the table height by an average of 2.3 cm) led to an 83% reduction in the median dose from 4.65 mGy to 0.79 mGy (P < 0.001). There were no significant differences between dose-reduction and conventional protocols in the kerma area product (7.34 vs. 7.40 Gy·cm², P = 0.892), air kerma (75.7 vs. 75.1 mGy, P = 0.872), and image quality. Conclusion: The lens radiation dose was significantly affected by table height adjustment during 3D-RA. Intentional head off-centering by elevation of the table is a simple and effective way to reduce the lens dose in clinical practice.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.6
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• pp.1083-1088
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• 2016

25.8kV GIS part generated by sensors to measure contact an inflow of noise depending on the extent of the measured discharge occurs often not easy. Partial discharge signal measurement sensor suitable for developing a more useful measurements at the scene to this, partial discharge waveform analysis developed a sensor, and to utilize forSensor on the development of the most important is VSWR decided to (voltage standing wave ratio) voltage standing-wave ratio less than 1.5 and decided less than at the full spectrum bands that are measured, this time Return loss, as measured value by absolute criteria 14.0 dB produced the sensor, designed to or more. UHF 1.5~0.5 GHz bandwidth spectrum to be measured in GIS. UHF bands were designed to be able to measure the best signal. Recently, 25.8kV GIS production company has been increasing variety of GIS were made open spacer in partial discharge in accordance with the not very easy to detect the signal. The sensor is designed height of four cm external spacer is attachment GIS in an influx of outside noise measurement, and be so manufactured as to facilitate the least we've done. Also, since partial discharge which occur can measure the frequency of the 170kV GIS external partial-discharge signals that occur at the scene of insulation applied to the spacer. Features, and also derived good results using global positioning. Also measured discharge point about sensors that are stable and the reliability of the development and local substation equipment failure occurring signal analysis through the discharge for the prevention of widely. There should be to believe that used.

• Tunnel and Underground Space
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• v.33 no.5
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• pp.425-434
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• 2023

To measure the wear amount of the TBM disk cutter in real time, it is important not only to automate the measurement using sensors, but also to stably transmit the measured data to the information processing system. In this study, we investigated the viability of utilizing Bluetooth Low Energy (BLE) technology to wirelessly transmit sensor data from the TBM cutter head to a receiver located at the chamber's rear. Through laboratory experiments, we analyzed the Received Signal Strength Index (RSSI) of the receiver considering various signal strength of the transmitter, separation distances between the transmitter and receiver and chamber fill materials. Our results demonstrate that wireless data transmission is feasible across all tested conditions when the transmitter signal strength is 0 dBm or higher.

• ETRI Journal
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• v.40 no.3
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• pp.366-375
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• 2018

Recently, techniques involving head-mounted displays (HMDs) have attracted much attention from academia and industry owing to the increased demand for virtual reality and augmented reality applications. Because HMDs are positioned near to users' eyes, it is important to solve the accommodation-vergence conflict problem to prevent dizziness. Therefore, holography is considered ideal for implementing HMDs. However, within the Nyquist region, the accommodation effect is limited by the space-bandwidth-product of the signal, which is determined by the sampling number of spatial light modulators. In addition, information about the angular spectrum is duplicated over the Fourier domain, and it is necessary to filter out the redundancy. The size of the exit-pupil of the HMD is limited by the Nyquist sampling theory. We newly propose a holographic HMD with an expanded exit-pupil over the Nyquist region by using the time-multiplexing method, and the accommodation effect is enhanced. We realize time-multiplexing by synchronizing a high-speed digital micromirror device and a liquid-crystal shutter array. We also demonstrate the accommodation effect experimentally.

• International Journal of Industrial Entomology and Biomaterials
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• v.6 no.1
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• pp.87-92
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• 2003

We describe here the cloning, expression and characterization of a cDNA encoding a putative chemosensory protein (CSP) from the mole cricket, Gryllotalpa orientalis. The G. orientalis chemosensory protein cDNA sequences comprised of 384 bp with 128 amino acid residues. The G. orientalis chemosensory protein showed 75.4% protein sequence identity to the Locusta migratoria CSP, Northern blot analysis revealed that signal was stronger in head than leg and cuticle, indicating that the head part containing antennae is a main site for G. orientalis chemosensory protein synthesis. The cDNA encoding G. orientalis chemosensory protein was expressed as approximately 12 kDa polypeptide in baculovirus-infected insect cells.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.05a
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• pp.1111-1116
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• 2001

A transient T-F(time-frequency) signal processing technique is applied to a tilt drop and a linear shock test rigs for identification of shock characteristics of hard disk drive (HDD). The T-F technique essentially tracks the shock characteristics of pivot point response as well as head slap and lift-off phenomena. From the T-F analysis result, the shock characteristic in HDD is modeled by the two degree of freedom coupled-dynamic system, which consists of actuator arm and suspension. As shock designing tool, the maximax shock response spectrum is employed for prediction of shock performance. Finally, the shock control technique is tested with newly designed actuator arm and suspension. Experimental head slap test result shows that the shock performance is much higher with the new shockproof designed model than the current model

• Journal of Korean Neurosurgical Society
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• v.29 no.12
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• pp.1682-1687
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• 2000

Progressive multifocal leukoencephalopathy(PML) is a fatal demyelinating disease that occurs in immunocompromised hosts. We report a case of PML that developed in patient with T cell lymphoma of head and neck. During chemotherapy for lymphoma, she was confused and had memory impairment. A magnetic resonance imaging of the brain revealed confluent signal change at white matter of the frontal lobe, insula, and anterior limb and genu of internal capsule. The lesion was confirmed with brain biopsy and the histopathological finding was compatible with PML.

• Transactions of the Society of Information Storage Systems
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• v.1 no.1
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• pp.99-107
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• 2005

According to recent trend, hard disk drive(HDD) has been smaller and less weight. Therefore, it needs new method of writing position information. In this thesis, a new controller that is suitable for SSW is proposed. The controller accepted SSW technology that is used to write position information in current HDD industry. The important condition to perform SSW is to reach constant velocity decided from the head velocity profile as fast as possible. The constant velocity decides the positional accuracy of spiral pattern and setup time decides the capacity of HDD. The head velocity profile as a reference signal must be designed not to cause resonance mode. The proposed controller was designed with consideration of these 3 elements, and it properly works for SSW. The velocity profile designed with SMART control not only minimizes the jerk, but also does not cause the resonance mode of a plant. After designing a conventional PID controller, it compared with electrical spring technique and ZPET technique.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.52 no.6
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• pp.709-718
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• 2019

Cephalopods, such as the Japanese flying squid Todarodes pacificus and golden cuttlefish Sepia esculenta, are an important food source for all toothed whales, particularly bottlenose dolphins in costal and offshore waters around the Korean Peninsula. A controlled laboratory experiment was conducted to investigate the broadband acoustic backscattering from live individuals of these two cephalopod species using linear chirp signals (100-200 kHz). The backscattered echo signal was measured at about 1° intervals from -45° (head down) to +45° (head up) in the dorsal plane. The species-specific, frequency-dependent scattering characteristics were investigated by comparing the relationship between the wavelength-normalized backscattering cross-section (σ/λ²) and the wavelength-normalized fish length L/λ for each species. The estimated σ/λ² value for Japanese flying squid was 9.51 at an L/λ range of 12.79-30.27 (mean, 21.26). This was approximately 7% of the σ/λ² value (136.1) for golden cuttlefish at an L/λ range of 9.07-25.49 (mean, 15.77).

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.1
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• pp.123-145
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• 2017

Due to the increasing demand for spectrum resources, cognitive radio networks and dynamic spectrum access draw a lot of research into efficiently utilizing limited spectrum resources. To set up cluster-based CR ad-hoc common channels, conventional methods require a relatively long time to successfully exchange the initialization messages. In this paper, we propose a fast and reliable common channel initialization protocol for CR ad-hoc networks. In the proposed method, the cluster head sequentially broadcasts a system activation signal through its available channels with a predetermined correlation pattern. To detect the cluster head's broadcasting channels and to join the cluster, each member node implements fast Fourier transform (FFT) and computes autocorrelation of an FFT bin sequence for each available channel of the member node. This is compared to the predetermined reference pattern. The join request and channel decision procedures are also presented in this paper. In a simulation study, the performance of the proposed method is evaluated.