• Journal of Digital Convergence
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• v.14 no.11
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• pp.45-51
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• 2016

Although the problem of personal data leakage is reported to be serious, there has been no research that tries to excavate out that real cause of the leakage in scientific prospective. Although this topic is considered to be crucial, there have been no literatures relevant to the topic, and the reason for this limitation is that scientific approach to this problem was not feasible. In this respect, in this paper a model for such scientific analysis and a methodology of analysis have been devised. Results show that the degree of rigidity turns out be the determinant that vindicates the degree of leakage. The notion of data rigidity is revealed to be very strongly correlated to the number of hacking incidents in each country. The notion of resident data freedom was then deployed in this paper to determine the world-wide ranking for a slew of different countries. The United Kingdom and the Republic of Korea turned out to be the two extreme countries that lie in the spectrum of the scale, with UK the most flexible and ROK one of the most rigid.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.8
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• pp.131-137
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• 2005

The purpose of this paper is to evaluate the axial magnetic flux measurement could be used as a tool of the condition monitoring system for the induction motor and to develope the diagnostic algerian for the electric motors. The magnetic leakage flux signal is captured by the flux coil located at the end of motor without the disturbance of the operation. And the signal is analyzed both time and frequency bases to detect the failure of the motor. Specific signature can be described in time and frequency domain for each faults of the motor. The spectrum of the signal was found more useful for the monitoring purpose. The supply voltage imbalance and tin to turn failure of the stator winding could be detected by analysing the specific sidebands of the axial flux and sideband of the rotor bar pass frequency with the high resolution spectrum. The goal of this study verity that the axial flux measurement for the induction motor is a powerful tool for the diagnostic method and develope the algorithm to detect the fault.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.2
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• pp.36-44
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• 2016

In this paper, an Impulse Radio-Ultra Wide band RF Transceiver for WBAN applications is implemented in $0.18{\mu}m$ CMOS technology. The designed RF transceiver support 3-5GHz UWB low band and employs OOK(On-Off Keying) modulation. The receiver employs non-coherent energy detection architecture to reduce complexity and power consumption. For the rejection of the undesired interferers and improvement of the receiver sensitivity, RF active notch filter is integrated. The VCO based transmitter employs the switch mechanism. As adapt the switch mechanism, power consumption and VCO leakage can be reduced. Also, the spectrum mask is always same at each center frequency. The measured sensitivity of the receiver is -84.1 dBm at 3.5 GHz with 1.579 Mbps. The power consumption of the transmitter and receiver are 0.3nJ/bit and 41 mW respectively.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.13 no.5
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• pp.334-340
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• 2003

Exponential window function Is widely used In impact hammer testing to reduce leakage error as well as to get a good S/N ratio. The larger its decaying rate is, the more effectively the leakage errors are reduced. But if the decay rate of the exponential window is too large, the FRF is distorted. And the modal parameters of the system can not be exactly identified by modal analysis technique. Therefore, it is a difficult problem to determine proper decay rate in impact hammer testing. In this paper, amount of the FRF distortion caused by exponential window is theoretically uncovered. A new circle fitting method is also proposed so that the modal parameters are directly extracted from impulse response spectrum distorted by the exponential-windowed impulse response data. The results by the conventional and proposed circle fitting method are compared through a numerical example.

• Journal of IKEEE
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• v.15 no.1
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• pp.1-9
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• 2011

Cable leakage criterion of technical regulations on CATV transmission system was reinforced considering interference against CDMA mobile communication system in 2007. The criterion is $3{\mu}V$/m(at 10m) over 824~849MHz. But generally it is difficult for us to decide if a given CATV transmission facilities conform to it or not through simple measurement methods. In this paper, the problems on measuring cable leakage is identified theoretically and the measuring model with spectrum analyzer, LNA, and antenna is proposed to settle the problems. Also, the model is proved to be useful by practically measuring outdoors and analysing the results and the process to decide to fit to the criterion or not is established.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.2
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• pp.413-421
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• 1990

Acoustic emission signals due to leak from circular holes of 0.4, 1, 2 and 4mm diameter and rectangular slits of different geometry having the same cross section as 4mm diameter hole was studied both analytically and experimentally. Acoustic emission signals from a wide-band type transducer were transformed to digital signals through a digital oscilloscope, and $V_{rms}$ and frequency spectrum were obtained by processing digital signals. Relationships between acoustic parameters and fluid mechanical parameters were derived analytically. A quadrapole aerodynamic model was applied in the analysis of leak from the circular holes and $V_{rms}$ was found to be proportional to the root square of leak rate through the circular hole. A modified model based on dipole source mechanism and laminar equivalent diameter was applied in the analysis of leak signals from the rectangular slits. In the case of constant pressure, $V_{rms}$ increased as the laminar equivalent diameter of slit decreased. In the case of constant laminar equivalent diameter, however the result was similar to that for leak from the circular hole. The frequency spectra of leak signals shows the same frequency characteristics irrespective of the pressure difference.rence.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.12 no.9
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• pp.702-708
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• 2002

The spectrum of impulse response signal from an impulse hammer testing is widely used to obtain frequency response function(FRF). However the FRFs obtained from impact hammer testing have not only leakage errors but also finite record length errors when the record length for the signal processing is not sufficiently long. The errors cannot be removed with the conventional signal analyzer which treats the signals as if they are always steady and periodic. Since the response signals generated by the impact hammer are transient and have damping, they are undoubtedly non-periodic. It is inevitable that the signals be acquired for limited recording time, which causes the errors. This paper makes clear the relation between the errors of FRF and the length of recording time. A new method is suggested to reduce the errors of FRF in this paper. Several numerical examples for 1-dof model are carried out to show the property of the errors and the validity of the proposed method.

• Transactions of the Korean hydrogen and new energy society
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• v.34 no.2
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• pp.205-211
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• 2023

Hydrogen gas is light and diffuses very quickly. Therefore, when a leakage accident occurs, the damage is great, so a technology that can quickly measure the leakage in the air at a long distance is needed. In order to develop hydrogen gas leaked in the atmosphere in a non-contact manner, an experiment was performed to measure hydrogen gas using a lidar technology using the Raman effect. Hydrogen Raman signals were detected using a UV LED light source, which is a Raman light source, and a spectrometer in the ultraviolet region including an optical filter in the 400-430 nm band. To develop this, a Raman lidar optical structure was designed to measure the hydrogen Raman signal at a certain distance, and the hydrogen Raman spectrum was confirmed using a standard gas to evaluate the performance of this optical structure. The linearity was found to be 0.99 using hydrogen standard gas (10, 50, 100, 500, 1,000 ppm). Accordingly, a Raman lidar capable of measuring hydrogen gas rapidly diffusing in the air in an open state was developed to improve the limitations of existing hydrogen sensors.

• The Journal of the Acoustical Society of Korea
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• v.31 no.7
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• pp.449-460
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• 2012

The importance of the leak detection of a buried pipe in a power plant of Korea is being emphasized as the buried pipes of a power plant are more than 20 years old. The objective of this work is to enhance the capability of the leak detection technique in a noisy environment. For this purpose, a modified cross-correlation method that can effectively remove the rotating machinery noise component is suggested. In addition, a method for leak point detection using phase information of cross-spectrum is suggested. The validity of the proposed method is verified by performing an experiment. The experimental result demonstrates that the performance of the cross-correlation method can be enhanced by reducing the periodic noise components due to mechanical equipment.

• Nuclear Engineering and Technology
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• v.51 no.5
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• pp.1209-1217
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• 2019

Due to the limitation of the computers, the conventional homogenization method is based on many assumptions and approximations, and some tough problems such as energy spectrum and boundary condition are faced. To deal with those problems, the Monte Carlo global homogenization is adopted. The Reactor Monte Carlo code RMC is used to study the global homogenization method, and the one-step global homogenization method is proposed. The superimposed mesh geometry is also used to divide the physical models, leading to better geometric flexibility. A set of multigroup homogenization cross sections is online generated for each mesh under the real neutron energy spectrum and boundary condition, the cross sections are adjusted by the superhomogenization method, and no leakage correction is required. During the process of superhomogenization, the author-developed reactor core program NLSP3 is used for global calculation, so the global flux distribution and equivalent homogenization cross sections could be solved simultaneously. Meanwhile, the calculated homogenization cross section could accurately reconstruct the non-homogenization flux distribution and could also be used for fine calculation. This one-step global homogenization method was tested by a PWR assembly and a small reactor model, and the results show the validity.