• Journal of the Korean Society for Aviation and Aeronautics
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• v.30 no.1
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• pp.44-49
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• 2022

This study performed precision instrument landing procedures for pilots with a commercial pilot license using VR HMD flight simulators, and assuming that the center of the pilot's gaze is in the front, 3-D.O.F. head tracking data and 2-D eye tracking of VR HMD worn by pilots gaze tracking was performed through. After that, AOI (Area of Interesting) was set for the instrument panel and external field of view of the cockpit to analyze how the pilot's gaze was distributed before and after the decision altitude. At the same time, the landing results were analyzed using the Localizer and G/S data as the pilot's precision instrument landing flight data. As a result, the pilot was quantitatively evaluated by reflecting the gaze tracking and the resulting landing result using a VR HMD simulator.

• Korean Journal of Optics and Photonics
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• v.25 no.1
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• pp.38-43
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• 2014

An external cavity laser supporting two wavelengths is demonstrated by incorporating polymer waveguide Bragg reflectors and a superluminescent light-emitting diode. An oversized rib waveguide structure and Bragg gratings are designed by using the effective-index and transmission-matrix methods. Bragg gratings with different periods are inscribed on a polymer waveguide through double-exposure laser interferometry. In order to tune the cavity loss affected by the reflectivity of Bragg gratings, a Bragg reflectors with varying length is incorporated. Two-wavelength-mode lasing is achieved for the device consisting of 2-mm long, 537-nm period gratings and 2.2-mm long, 540-nm period gratings; the lasing wavelengths are 1554 nm and 1564 nm, with an output power close to 0 dBm, a 20-dB bandwidth of 0.2 nm, and a side-mode suppression ratio of 45 dB.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.10
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• pp.769-778
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• 2017

In this paper, a self-interference signal cancellation(SIC) circult for In-band Full-Duplex has been developed and tested in RF/analog region. By use of this SIC circuit, a FM two-way radio has been developed working at FRS(Family Radio Service) band. The two-way radio device is transmitting the FM modulated signal and demodulating the wanted FM signal at the same time. A circulator is used to enable a single antenna to transmit and receive simuultaenously. The receiver circuit needs to cancel out the self-interference signal due to the transmit signal. A vector modulator(VM) is used to control the phase and magnitude of the esitmated signal. And in-phase and quadrature correlators are used to figure out the optimal coefficients of the VM to remove the self-interference signal according to the change of channel environment. In this work, SA58646 has been used as the FM transceiver, and the system is tested with a frequency of 465 MHz and a bandwidth of 12.5 kHz FM signal. The output power is 17.2 dBm at the antenna port, and the self intererence signal level is measured -49.2 dBm at the receiver end. Therefore the SIC level is measured by 66.4 dB.

• Sleep Medicine and Psychophysiology
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• v.17 no.2
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• pp.100-108
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• 2010

Objectives: "Internet-addiction" came into common use not only in clinical setting but also in everyday life. But, pathophysiology and diagnostic criteria of the internet addiction remain unknown. Because adolescents are in developing period, they might be vulnerable to the internet addiction, depression and sleep-related problem. The objectives of this study were to investigate the characteristics of internet addiction and its association with sleep pattern and depression in Korean adolescence. Methods: Subjects were 799 middle and high school students in Seoul, Korea. We administered a self-reported questionnaire including socio-demographic data, Korean versions of Young's Internet Addiction Scale (YIAS), Pittsburgh Sleep Quality Index (PS-QI), the Center for Epidemiologic Studies for Depression Scale (CES-D) and questions about internet using patterns. Data of 696 subjects were included in analysis. Chi-square tests were used to analyze proportional differences, and ANOVA with post-hoc tests were used to analyze differences among groups. Partial correlation analyses were performed to analyze the correlation of internet addiction with other variables (two-tailed, p<0.05). Results: Of the 696 participants (grade 2 of middle school; M2 135 vs. grade 1 of high school; H1 238 vs. grade 2 of high school; H2 323), 2.0% (n=14) were internet-addicted (IA), 27.7% (n=193) were over-using (OU) and 70.3% (n=489) were not-addicted (NA). The mean scores of YIAS, PSQI and CES-D scores were 35.24${\pm}$12.78, 5.53${\pm}$3.04 and 16.72${\pm}$8.69, respectively. In higher grade students, average total sleep time was shorter (M2 426.20${\pm}$67.68 min. vs. H1 380.47${\pm}$62.57 min. vs. H2 354.67${\pm}$73.37 min., F=51.909, p<0.001), and PSQI (4.69${\pm}$3.14 vs. 5.42${\pm}$3.15 vs. 5.97${\pm}$2.83, F=8.871, p<0.001) CES-D (13.53${\pm}$8.37 vs. 16.96${\pm}$8.24 vs. 17.87${\pm}$8.84, F=12.373, p<0.001) scores were higher than those of lower grade students. Comparing variables among IA, OU and NA groups, computer using time not for study (96.36${\pm}$63.31 min. vs. 134.92${\pm}$86.79 min. vs. 213.57${\pm}$136.87 min., F=34.287, p<0.001) and portable device using time not for study (84.22${\pm}$79.11 min. vs. 96.97${\pm}$91.89 min. vs. 152.31${\pm}$93.64 min., F= 5.400, p=0.005) were different among groups. PSQI (5.26${\pm}$2.97 vs. 6.08${\pm}$2.97 vs. 7.50${\pm}$4.41, F=8.218, p<0.001) and CES-D scores (15.40${\pm}$8.08 vs. 19.05${\pm}$8.42 vs. 30.43${\pm}$13.69, F=32.692, p<0.001) were also different among groups. YIAS score were correlated with computer using time not for study (r=0.356, p<0.001) and portable device using time not for study (r= 0.136, p<0.001). PSQI score (r=0.237, p<0.001) and CES-D score (r=0.332, p<0.001). YIAS score and PSQI score (r=0.131, p= 0.001), YIAS and CES-D score (r=0.265, p<0.001), PSQI score and CES-D score (r=0.357, p<0.001) were correlated each other. Conclusion: These results suggested that adolescents' internet-addiction was correlated with not only computer and portable device using time not for study but also depression and sleep-related problems. We should pay attention to depression and sleep-related problems, when evaluating internet-addiction in adolescents.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07b
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• pp.1413-1415
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• 2005

The OTFT performance depends strongly on the interfacial properties between an organic semiconductor and ${\alpha}$ metal electrode. The contact resistance is critical to the current flow in the device. The contact resistance arises mainly from the Schottky barrier formation due to the work function difference between the semiconductor and electrodes. We doped pentacene/source-drain interfaces with $F_4TCNQ$ (2,3,5,6-Tetrafluoro-7,7,8,8-tetracyanoquinodimethane), resulting in p-doped region at the SD contacts, in order to solve this problem. We found that the mobility increased and the threshold voltage decreased.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.8
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• pp.706-710
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• 2008

The substrate bias effect on the current level of SOI-MOSFETs for high temperature operation has been investigated. In this work, we demonstrate the current level of SOI-MOSFETs can be controlled at different temperatures by applying a control bias to the substrate, showing that all current levels below T=150$^{\circ}C$ can be adjusted to a constant current level. 2D numerical simulation results show that substrate bias effectively controls the current conduction; as the substrate bias effectively lower the potential of the channel, inversion carrier generation is effectively controlled and consequently a constant current conduction level is achieved up to T=150$^{\circ}C$. We also demonstrate that the device simulated in this work has same operation at any temperature below T=150$^{\circ}C$ through mixed mode simulation.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.6
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• pp.158-163
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• 1996

In the conventional GaAs MESFET circuit simulation, the DC and transient simulation results are often failed due to the discontrinuities of the first and second order derivatives arising from the use of separate C-V models in linear, satruration, and transition regions. In this paper, we propose a unified capacitance model for linear, transition, and saturation regions by using a unified channel length modulation effect that is derived by extending the channel length modulation effect in the saturation region to the linear region. Calculated resutls from the proposed capacitance model agree well with 2-D device simulation resutls. Thus, the proposed model is expected to be useful in circuit simulation.

• ETRI Journal
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• v.35 no.2
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• pp.348-351
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• 2013

Cloud computing has recently become a significant technology trend in the IT field. Among the related technologies, desktop virtualization has been applied to various commercial applications since it provides many advantages, such as lower maintenance and operation costs and higher utilization. However, the existing solutions offer a very limited performance for 3D graphics applications. Therefore, we propose a novel method in which rendering commands are not executed at the host server but rather are delivered to the client through the network and are executed by the client's graphics device. This method prominently reduces server overhead and makes it possible to provide a stable service at low cost. The results of various experiments prove that the proposed method outperforms all existing solutions.

• Journal of Magnetics
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• v.22 no.1
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• pp.14-22
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• 2017

The NMR's probe consists of the static magnetic field generator (magnetic source) and the RF coil. It is very strict for the homogeneity of the static magnetic field intensity of the magnetic source, so the cost of the magnetic source is more expensive in the entire nuclear magnetic resonance instrument. The magnetic source generally consists of electromagnet, permanent magnet and superconducting magnet. The permanent magnet basically needs not to spend on operation and maintenance and its cost of manufacture is much cheaper than the superconducting magnet. Therefore, the permanent magnet may be the only choice for the static magnetic field device if we want to use the magnetic resonance instrument as an analyzer for production by reducing price. A new probe magnet was developed on the basis of the permanent magnet ring in this paper to provide a technological way for reducing the manufacturing cost, weight and volume of the existing nuclear magnetic resonance instrument (including MRI) probe.

• Journal of the Korean Solar Energy Society
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• v.23 no.2
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• pp.35-41
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• 2003

In order to investigate the offshore wind resources around Korean peninsula, the "QuikSCAT Level 3" data by ADEOS II satellite was analyzed from Jan 1 2000 to Jan 18 2003. The "SeaWinds" on the satellite is a specialize4 device for microwave scatterometery that measures near-surface wind speed and direction under all weather and cloud conditions. Wind speed are extrapolated from 10m to 60m with the exponent of 1/10 in the power law model. It has been found that the High wind energy potentials are prevailing in the South sea and Southeastern end of Korean peninsula.