• Journal of Ocean Engineering and Technology
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• v.25 no.2
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• pp.120-126
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• 2011

The fatigue damages in structural details of offshore plants can be accumulated due to various environmental loadings such as swell, wave, wind and current. It is known that load histories acting on mooring and riser systems show stationary and ergodic bimodal wide-banded process. This paper provides refined approach to obtain time signals representing stress range histories from wide-banded bimodal spectrum which consists of ideally narrow-banded and fully separated two spectrums. Variations of the probabilistic characteristics for time signals according to frequency and sampling time increments are compared with the reference data to be the probabilistic characteristics such as zero-crossing period, peak period, and irregularity factor obtained from an assumed ideal spectrum. It is proved that the sampling time increment more affects on the probabilistic characteristics than frequency increment. The fatigue damages according to the frequency and sampling time increments are also compared with the ones with minimum increment condition which are thought to be exact fatigue damage. It is concluded that the maximum sampling time increment to obtain reliable time signals should be determined that ratio of applied maximum sampling time increment and minimum period is less than approximately 0.08.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.10
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• pp.932-935
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• 2015

This paper proposes a rectifier using bootstrapping and active body biasing in $0.11{\mu}m$ RF CMOS process. The proposed rectifier employs the full-wave rectifying structure with cross coupling and increases the power conversion efficiency by reducing the threshold voltage and leakage current using bootstrapping and active bias biasing. Also, it has been designed to be applied to a wide range of applications from 13.56 MHz used in wireless power transmission to 915 MHz used in RFID. As a measured result, 80 % of power conversion efficiency is obtained when the input power is 0 dBm at $10k{\Omega}$ load resistance and 13.56 MHz. Also 40 % of power conversion efficiency is shown in 915 MHz.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.12
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• pp.1140-1147
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• 2013

In this paper, The path loss model of Air Traffic Control(ATC) telecommunication radio channel has been studied at the Incheon International Airport(IIA) Cargo Terminal. We measured one frequency among VHF channel bands. The transmitting site was located at different locations with different heights. The transmitting site radiated the Continuous Wave(CW). The propagation measurement was taken using the moving vehicle equipped with receiver and antenna. The transmitting power, frequency and antenna height are the same as the current operating condition. The path loss exponent and intercept parameters were extracted by the basic path loss model and hata model. The path loss exponent at IIA Cargo terminal area were 3.67 and 3.39 respectively in first and second transmitting sites. The deviation of prediction error is 14.42 and 10.38. The new path loss equation at the IIA Cargo terminal area was also developed using the derived path loss parameters. The new path loss was compared with other models. This result will be helpful for the ATC site selection and service quality evaluation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.10
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• pp.3917-3922
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• 2010

In this paper, 3 stage amplifier MMIC was designed and fabricated with U-band optimized epitaxal pHEMT that produced by large signal characterization and modeling for 60 GHz band. The pHEMT used in this paper, the gate $0.12\;{\mu}m$ length and total gate width of $100\;{\mu}m$, $200\;{\mu}m$ has been modeled using the large signal designed with negative feedback and MCLF instead of MIM capacitor for improving stability. Fabricated MMIC $2.5{\times}1.5mm^2$ size, current about 40 mA, operating frequency 59.5~60.5 GHz, gain 19.9~18.6 dB, input matching characteristics -14.6~-14.7 dB, output matching characteristics -11.9~-16.3 dB and output -5 dBm characteristics were obtained.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.10
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• pp.1383-1389
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• 2013

There were telecommunication noise and malfunctions of the electronic devices occurred over a wide area due to the high harmonic voltage and/or current levels of the Back-to-back converter in the DFIG wind power system even though the magnitude of all harmonics is within the international standards. The triangular carrier signals of the PWM used in the power converter system is related to the telecommunication noise because they are in the range of audible frequencies and amplified by a variety of the standing waves that were excited by harmonic voltage sources in the weak grid system such as a long distance distribution transmission lines. This paper describes the characteristics of the harmonics in the wind turbine-generator, numerical analysis and simulation of the harmonics resonance phenomena in the distribution lines as well as measuring induced voltage of the telecommunication lines in parallel with power lines in order to verify the root cause of the telecommunication noise. These noise problems can occur in a wind turbine power system with a non-linear converter at any time, as well as photovoltaic power system. So, the preliminary review of suitable filter devices and switching frequencies of the PWM have to be required by considering the stability of the controller at the design stage but as part of the measures the effect of the telecommunication cable shields was analyzed by comparing the measured data between multi-conductor with/without shields so as to attenuate the sources of the harmonics voltage induced into the telecommunication lines and to apply the most cost-effective measures in the field.

• Journal of Korea Multimedia Society
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• v.12 no.5
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• pp.664-676
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• 2009

As data broadcasting has become available, diverse contents can now be provided through digital TV, IPTV and DMB; yet it is true in the current situation that killer contents are insufficient that can satisfy users. On the contrary, in case of the web, with the advent of web 2.0 aiming at user-centered services, the contents market has grown greatly. The ideas and technologies of Web 2.0, if gratified into data broadcasting, are expected to make a contribution to the vitalization of contents. This paper proposes a method of using RSS, as a concrete example of applying web 2.0 to data broadcasting. Accordingly, we have developed a system for producing data services for the ground wave DMB data broadcasting, by using RSS at the stage of authoring news and the like, for which provision of the latest information is important. And for IPTV, we have developed a data broadcasting application so that users can select the RSS they want, as well as a creation system for using RSS at the authoring stage. It is anticipated that the application of RSS by means of the system will simplify the authoring process, making easy the provision of the latest information through the web, and thereby making possible the provision of diverse services to users.

• Journal of the Korea Computer Industry Society
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• v.2 no.12
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• pp.1563-1572
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• 2001

Information wave of 21th century industrial society being undergone a change to knowledge post-industrial society new sense of values and life require. Also, computer is interacting, and adapts spontaneously in current enemy these age by important means on information-oriented society that change rapidly and computer-aided education is essential to improve country competitive power. Grasp computer education actual conditions of vocational high school for positivity that is industrial technology that IT base knowledge information-oriented society requires in this research hereupon, and though students' profession preference wishes to supply pabulum in course education presenting improvement direction of more efficient computer-aided education through investigation, there is the purpose. In present school curriculum, satisfaction about computer connection education responded that have interest much very appeared in general high. Also, computer connection profession preference was expose that research results keep in step and prefers most Information Communication Technology (ICT) field and multi media field that is embossed newly in post-industrial society.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.4
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• pp.933-939
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• 2015

If the Visual Aids(light wave signs) is not supplied the general power it is using solar power system. These power supply systems, the role of the charge/discharge control is very important. Introduction of IT(AIS etc.) for the effective management of the AtoN(Aids to Navigation) is a Visual Aids has been added to the device using the power to charge/discharge control, the need increases. The current charge/discharge controller is attached to the inside of the AtoN and checks on and verification of the maritime environment, depending on the difficulty. In order to resolve these issues in this paper, the Bluetooth module is mounted on the inside of the charge/discharge controller and proposed a possible system monitoring at close range. Advantage of the system implemented is a simple configuration and low installation cost. In addition, it can be applied to a variety of AtoN. Also, it has been able to check the real-time status information of the charge/discharge controller at a short distance in to reduce inspection costs, and reduce risk factors that might occur during check.

• The Journal of Korean Physical Therapy
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• v.6 no.1
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• pp.171-183
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• 1994

Purphose. This present study examines the effect of brief, intense transcutaneous electrical nerve stimulation(BTENS) on sensory nerve conduction, electrical pain threshold, and two-point discrimination measured at the superficial radial nevre distribution in 20 healthy subjects. Subjects. Twenty volunteercs, (10 females and 10 males(age range : 20-38 years : $mean{\pm}SD\;:\;27.00{\pm}5.12$), only subjects without prior traumatological and pathological were eligible to participated in this study. Methods. Nerve conduction were determined for the right superficial radial nerve. Electrical pain threshold were determined for the right wrist ipsilateral to the site of BTENS. Small disc electrodes were attached to the surface of the skin stradding the end of the radius. Square wave electrical pulses were delivered from an isolated stimulator through a constant current device at a frequency of 2 Hz(5 ms pulse width). Two-point discrimination, measured on the sensory distribution of superficial radial nerve. BTENS was delivered using a Max-SD( Medical design co.) portable battery powered stimulator. A cicular Ag/AgCl electrode in contact with hypertonic saline gel was attached to the lateral(radial side) surface of the forearm. Results. No significant effects were observed between stimulation methods in the prestimulation cycle(multi-way ANOVA repeated measures : distal latency ; F1.14=0.332. amplitude ; F 0.80=0.445, pain threshold ; F0.06=0.940.2 point discrimination ; F1.50=0.236). Highly significant effects were observed time with the pretreatment and 6 posttreatment cycles(p<0.01). Mighty significants differences in nerve conduction and pain threshold were found using un multi-way ANOVA repeated measures among stimulation methods for each cycles(p<0.01). Conclusion and Discussion The authors concludes that both nerve conduction and pain threshold changes are associated with therapy (stimulation) level of BTENS.

• Progress in Superconductivity
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• v.9 no.1
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• pp.35-39
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• 2007

Myocardial ischemia causes heterogeneity of ventricular repolarization and sometimes produces changes of the ST-T wave in ECG. Therefore, morphological changes of ST-T waveform in ECG have a clinical significance in diagnosing myocardial ischemia. In this study, we investigated the ST-T changes caused by myocardial ischemia in magnetocardiography (MCG). We analyzed MCG patterns of biphasic T, ST segment deviations from baseline, main current angle of $T_{peak}$ and $T_{peak}$ dispersion in 300 CAD patients without ST elevation in ECG, 122 symptomatic patients and 48 normal subjects. MCGs were recorded by multichannel SQUID system in a magnetically shielded room. As results, we found that appearances of the abnormality were strongly correlated with the severity of myocardial ischemia. Also we found that the percentage of the patients showing MCG changes were higher than those in ECG. These results show that morphological changes of ST-T waveform in MCG can be used as a marker of myocardial ischemia.