• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.10
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• pp.1774-1779
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• 2016

This paper proposes a portable cable fault detection system with automatic fault distinction and distance measurement using time-frequency correlation and reference signal elimination method and automatic fault classification algorithm in order to have more accurate fault determination and location detection than conventional time domain refelectometry (TDR) system despite increased signal attenuation due to the long distance to cable fault location. The performance of the developed system method was validated via an experiment in the test field constructed for the standardized performance test of power cable fault location equipments. The performance evaluation showed that accuracy of the developed system is less than 1.34%. Also, an error of automatic fault type and location by detection of phase and peak value through elimination of the reference signal and normalization of correlation coefficient and automatic fault classification algorithm not occurred.

• Proceedings of the KIEE Conference
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• 2000.11b
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• pp.398-401
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• 2000

This paper describes the design of optimal location and capacity of DC substation for Mass Transit System. Three factors are considered for the design i.e. substation arrangements, line configuration and substation power capacity. In this study, we considered all of them for capacity calculation of power supply system for MTS. At first, DC-fed-traction system is introduced on an outline, a characteristics of train and fed network, and design method of substation arrangements. Optimal design procedures are described, and program for capacity calculation of the system is presented. In addition, the computer simulated results are compared with the conventional simple calculation method.

• Fire Science and Engineering
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• v.18 no.2
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• pp.41-48
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• 2004

We have conducted a numerical simulation under three-dimensional unsteady conditions in order to analyze the characteristics of $CO_2 $;, extinguishant transfer by varying the location of the injection nozzle, which affects the effect of a $CO_2 $;, fire fighting system used in the form of fixed systems for the marine engine room. Flow fields and $CO_2 $;, concentration fields were measured according to the location of the injection nozzle. In the case of arranging the injection nozzle on the center of the ceiling, the low-normal concentration distribution was developed along the $CO_2 $;, jet due to the downward flow created by impinging ceiling jets in the symmetric plane. The concentration line reaches its peak due to the mass transfer of $CO_2 $;, at the comer.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.3
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• pp.448-458
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• 2020

Indoor positioning based on trilateration using common chord estimates location of a mobile subject by using intersection points between each circles which the radius is same as distance between the mobile subject and each radio-frequency transmitter. However, if the intersection points are not found due to error of the distance measurement, it causes failure of estimating the mobile subject's location. To prevent this case, numbers which is proportionate to radius of each circles, are temporarily added to each distances in order to lengthen radius of the circles. Although the estimated location includes error due to the radius extension, it is corrected again by the added value and distance from reference point. With introduction of the advanced correction algorithm, potential issues of existing trilateration such as failure of estimating location and distance measurement error will be minimized.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.9
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• pp.3412-3431
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• 2015

This paper considers the effect of co-channel interference on hybrid satellite-terrestrial relay network. In particular, we investigate the problem of amplify-and-forward (AF) relaying in hybrid satellite-terrestrial link, where the relay is interfered by multiple co-channel interferers. The direct link between satellite and terrestrial destination is not available due to masking by surroundings. The destination node can only receive signals from satellite with the assistance of a relay node situated at ground. The satellite-relay link is assumed to follow the shadowed Rice fading, while the channels of interferer-relay and relay-destination links experience Nakagami-m fading. For the considered AF relaying scheme, we first derive the analytical expression for the moment generating function (MGF) of the output signal-to-interference-plus-noise ratio (SINR). Then, we use the obtained MGF to derive the average symbol error rate (SER) of the considered scenario for M-ary phase shift keying (M-PSK) constellation under these generalized fading channels.

• Journal of Sensor Science and Technology
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• v.26 no.6
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• pp.371-378
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• 2017

An accurate and robust estimation of center of rotation (CoR) using optical marker trajectory is crucial in human biomechanics. In this regard, the performances of the two prevailing least-squares methods, the Gamage and Lasenby (GL) method, and the Chang and Pollard (CP) method, are verified in this paper. While both methods are sphere-fitting approaches in closed form and require no tuning parameters, they have not been thoroughly verified by comparison of their estimation accuracies. Furthermore, while for both methods, results for stationary CoR locations are presented, cases for perturbed CoR locations have not been investigated for any of them. In this paper, the estimation performances of the GL method and CP method are investigated by varying the range of motion (RoM) and noise amount, for both stationary and perturbed CoR locations. The difference in the estimation performance according to the variation in the amount of noise and RoM was clearly shown for both methods. However, the CP method outperformed the GL method, as seen in results from both the simulated and the experimental data. Particularly, when the RoM is small, the GL method failed to estimate the appropriate CoR while the CP method reasonably maintained the accuracy. In addition, the CP method showed a considerably better predictability in CoR estimation for the perturbed CoR location data than the GL method. Accordingly, it may be concluded that the CP method is more suitable than the GL method for CoR estimation when RoM is limited and CoR location is perturbed.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.15 no.5
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• pp.104-113
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• 2006

The main objective of this study is to investigate the effect of compounded welding by using acoustic emission (AE) signals and doing a source location for weld heat affected zone (HAZ) through tensile testing. This study was carried out an SWS 490A high strength steel for electric shield metal arc welding, SMAW; $CO_2$ gas metal arc welding, GMAW($CO_2$); and gas tungsten arc welding, GTAW/TIG. Data displays are based on the measured parameters of the AE signals, along with environmental variables such as time and load. For instance, Gutenberg-Richter magnitude-frequency relationship (G-R MFR) offers useful b-value in data analysis. Namely event identification, source location gives the X- and Y-coordinates of the AE source. And K-means clustering analysis by Euclidean distance confirmed that was powerful to source location. Generally, strength of welded metal zone was stronger than strength of base metal. As the result, confirmed certainly that fracture is produced in HAZ instead of welded metal zone from source location.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.8
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• pp.1442-1449
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• 2016

This paper proposes a diagnosis to detecting poor contact fault and fault location. Electrical fire by poor contact fault of power cable occupied a large proportion in the total electrical installations. The proposed method has an object to prevent electrical fault in advance. But detecting poor contact fault is difficult to detect fault type and fault location by using conventional reflectometry due to faults generated intermittently and repeatedly on the time change. Therefore, in this paper poor contact fault and fault conditions were defined. System generating poor contact fault produced for the experimental setup. SSTDR and algorithm of reference signal elimination heighten performance detecting poor contact fault on live power cable. The diagnosis methods of signal process and analysis of reflected signal was proposed for detecting poor contact fault and fault location. The poor contact fault and location had been detected through proposed diagnosis methods. The fault location and error rate of detection were verified detecting accuracy by experiment results.

• Journal of Soil and Groundwater Environment
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• v.22 no.3
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• pp.42-49
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• 2017

TOUGH2 was used to simulate the migration of $CO_2$ injected into a sandy aquifer. A series of numerical simulations was performed to investigate the effects of a low-permeability layer (LPL) embedded in the aquifer on the injection rate and the pressure distribution of $CO_2$. The results show that the size and location of the LPL greatly affected the spread of $CO_2$. The pressure difference between two points in the aquifer, one each below and above the LPL, increased as the size of the LPL increased, showing a critical value at 200 m, above which the size effect was diminished. The location of the LPL with respect to the injection well also affected the migration of $CO_2$. When the injection well was at the center of the LPL, the injection rate of $CO_2$ decreased by 5.0% compared to the case with no LPL. However, when the injection well was at the edge of the LPL, the injection rate was decreased by only 1.6%. The vertical distance between the injection point and the LPL also affected the injection rate. The closer the LPL was to the injection point, the lower the injection rate was, by up to 8.3%. Conclusively, in planning geologic storage of $CO_2$, the optimal location of the injection well should be determined considering the distribution of the LPL in the aquifer.

• International Journal of Highway Engineering
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• v.18 no.2
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• pp.103-110
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• 2016

PURPOSES: In this paper, the effectiveness of speed-maintained standardization in road geometry on environmental impact at a downward slope location, based on greenhouse gas (GHG) emission indicators, was studied. Specifically, the aim of this study was to ascertain whether speed-maintained standardization resulted in decreased $CO_2$ emissions as well as noise pollution, due to reduced vehicle speeds. METHODS : In this study, speed-maintained standardization in road geometry was proposed as a means to reduce vehicle speeds, with a view to reducing $CO_2$ emissions and noise pollution. This technique was applied at a downward slope location. The vehicle speeds, $CO_2$ emissions, and noise levels before and after application of speed-maintained standardization were compared. RESULTS: It was found that speed-maintained standardization was effective as a means to reduce speed, as well as $CO_2$ emissions and noise pollution. By applying speed-maintained standardization, it was confirmed that vehicle speeds were reduced consistently. As a result, $CO_2$ emissions and noise levels were decreased by 9% and 11%, respectively. CONCLUSIONS : This study confirmed that speed-maintained standardization in road geometry is effective in reducing vehicle speeds, $CO_2$ emissions, and noise levels. Moreover, there is further scope for the application of this method in the design of roads in urban and rural areas, as well as in the design of highways.