• Journal of the Korea Institute of Military Science and Technology
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• v.17 no.3
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• pp.342-349
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• 2014

MRDS is a short range missile/rocket defense system which protects a main battle tank(MBT) from threats in a short range. It is composed of 2 radars, 2 infrared trackers(IRTs), 1 fire control computer(FCC), 2 launchers and countermeasures. To guarantee the performance of the MRDS, these components have to be mounted on the vehicle with the known positions and directions and it is required to compensate the alignment errors. In this paper, a system alignment method using angular error compensation is proposed to install its components within a tolerance on the MBT. The test results are presented to evaluate and verify the effectiveness of the proposed method.

• Journal of information and communication convergence engineering
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• v.10 no.2
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• pp.200-204
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• 2012

This study has presented the analysis of breakdown voltage for a double-gate metal-oxide semiconductor field-effect transistor (MOSFET) based on the doping distribution of the Gaussian function. The double-gate MOSFET is a next generation transistor that shrinks the short channel effects of the nano-scaled CMOSFET. The degradation of breakdown voltage is a highly important short channel effect with threshold voltage roll-off and an increase in subthreshold swings. The analytical potential distribution derived from Poisson's equation and the Fulop's avalanche breakdown condition have been used to calculate the breakdown voltage of a double-gate MOSFET for the shape of the Gaussian doping distribution. This analytical potential model is in good agreement with the numerical model. Using this model, the breakdown voltage has been analyzed for channel length and doping concentration with parameters such as projected range and standard projected deviation of Gaussian function. As a result, since the breakdown voltage is greatly changed for the shape of the Gaussian function, the channel doping distribution of a double-gate MOSFET has to be carefully designed.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39A no.1
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• pp.43-49
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• 2014

This paper proposes an optimized multi-bit digital FSK receiver robust to large carrier frequency offset (CFO) toward recently emerging long-range WPAN standards. Due to a short preamble length and strict BER requirements, we design a simple multi-bit digital demodulator combined with CFO estimator which guarantees the target BER performance. Simulation results verify that the proposed FSK receiver achieves CFO-free BER performance with the short preamble and satisfies the BER requirement by the recent WPAN applications.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.1
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• pp.107-112
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• 2015

This paper introduces an evolutionary nonlinear regression based compensation technique for the short-range prediction of wind speed using AWS(Automatic Weather Station) data. Development of an efficient MOS(Model Output Statistics) is necessary to correct systematic errors of the model, but a linear regression based MOS is hard to manage an irregular nature of weather prediction. In order to solve the problem, a nonlinear and symbolic regression method using GP(Genetic Programming) is suggested for a development of MOS wind forecast guidance. Also FCM(Fuzzy C-Means) clustering is adopted to mitigate bias of wind speed data. The purpose of this study is to evaluate the accuracy of the estimation by a GP based nonlinear MOS for 3 days prediction of wind speed in South Korean regions. This method is then compared to the UM model and has shown superior results. Data for 2007-2009, 2011 is used for training, and 2012 is used for testing.

• Journal of Advanced Marine Engineering and Technology
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• v.36 no.1
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• pp.166-171
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• 2012

In this paper, short-range underwater wireless communication technique using visible LEDs is proposed. As an alternative to conventional acoustic system, visible LED communications show high quality and high speed data transmission characteristics. We design a frequency modulation-based optical wireless audio transmission system. The CD4046B phase-locked loop device is applied to implement the frequency modulation and demodulation. With a transmission modulation of 100 kHz, audio signal has successfully received at a transmission distance of 30 cm.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.10 no.3
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• pp.79-84
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• 2011

In this paper, we analyzed performance of vehicle detection for ITS (Intelligent Transport System) applications. We simulated the vehicle detection at Hi-Pass System is based on DSRC (Dedicated Short Range Communication). DSRC is a wireless network using ITS, including GPS (Global Positioning System) satellites in conjunction with the national transportation system. The system performance is evaluated in terms of bit error probability. In the simulation, the vehicle speed is set at 60 km/h and carrier frequency is 5.8 GHz. Wireless channel is modeled as the Rician fading channel. In the transmitter, the ASK (amplitude shift keying) modulation scheme is applied. From simulation results, we confirmed that performance of applied Alamouti scheme is better than other systems.

• Proceedings of the KIEE Conference
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• 2007.04a
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• pp.261-263
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• 2007

Authentication is a mechanism to establish proof of identities, the authentication process ensure that. Who a particular user is. Nowadays PC and laptop user authentication systems are always done once a hold until s explicitly revoked by the user, or asking the user to frequently reestablish his identity which encouraging him to disable authentication. Zero-Interaction Authentication (ZIA) provides solution to this problem. In ZIA,. a user wears a small authentication token that communicates with a laptop over a short-range, wireless link. ZIA combine authentication with a file encryption. Here we proposed a Laptop-user Authentication Based Mobile phone (LABM). In our model of authentication, a user uses his Bluetooth-enabled mobile phone, which work as an authentication token that provides the authentication for laptop over a Bluetooth wireless link, m the concept of transient authentication with our combining It with encryption file system. The user authenticate to the mobile phone infrequently. In turn, the mobile phone continuously authenticates to the laptop by means of the short-range, wireless link.

• Applied Science and Convergence Technology
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• v.24 no.6
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• pp.254-256
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• 2015

Effect of growth temperature ($T_g$) on the structural and optical properties of $In_{0.5}Ga_{0.5}As$ atomic layer epitaxial (ALE) quantum dots (QDs) is investigated in the range of $T_g=480-510^{\circ}C$. $In_{0.5}Ga_{0.5}As$ ALE QDs consist of 5 periods of short-period superlattices (SPSs) of 1 monolayer-thick InAs and GaAs. Number of coalescent QDs decreases as $T_g$ increases, and they disappear at $T_g=510^{\circ}C$. As $T_g$ increases in the range of $480-495^{\circ}C$, sizes of QDs increase, and densities of QDs decrease due to merge of QDs. On the contrary, although sizes of QDs are maintained at $T_g=495-510^{\circ}C$, densities of QDs decrease. This is attributed to the desorption of material-mainly indium-during the growth interruption. This conjecture is supported by the optical properties of the QDs as a function of $T_g$. As a result, we propose that optimum growth temperature of the QD is $495^{\circ}C$ with less repetition of SPSs than 5.

• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.1
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• pp.87-95
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• 1989

The fatigue crack propagation of random short fiber SMC composite material was investigated. In macroscopic viewpoint, SMC composite material was treated as isotropic material and was analyzed in terms of conventional fracture mechanics. Experiments were conducted on mode I and mixed respectively and various loading level was applied to each mode. Fatigue crack growth can be explained in three steps and most of fatigue life is consumed in initial crack growth. In this experiments, power law, i.e, da/dN=C(C.DELTA.K)$^{m}$ , between fatigue crack growth rate and stress intensity factor range, was valid and the value of the exponent m is about 10, which is much higher than that of other metals. Fracture mechanism was also investigated by SEM fractographic study.

• Journal of Aquaculture
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• v.10 no.2
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• pp.189-197
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• 1997

A series of short (8 hours) and long term (96 hours) exposure studies was conducted on a laboratory scale to evaluation (1) the threshold concentrations of petroleum hydrocarbon in seawater which can lead to tainting problems in yellow tail (Seriola quinqueradiata) and (2) the time to recover (depuration period) once the tainting has occurred. The water-soluble fraction (WSF) of crude oil was prepared by stirring the oil with cold seawater. The main component of the WSF were low-boiling aromatics, although these were only al small proportion of the starting oil. From the sencory evaluation it was concluded that the threshold hydrocarbon levels in seawater which will impart a taint in yellow tail fillets within a 8-hour exposure period (short exposure period) are in the range of 0.4 to 1.0 ppm and within a 96-hour exposure period (long exposure period) are in the range of 0.2 to 0.5 ppm. Depuration trials were carried out with WSF from crude oil. The fish were exposed for 48 hours to concentration of 2.5 ppm hydrocarbons. After 48-hour exposure period, the fish were allowed to depurate in fresh, uncontaminated seawater. Depuration time for these fish was 10 days. The taste panelists were able to detect the contaminated fillets very easily while the depurated fish could not be distiguished from the control.