• The Journal of Engineering Geology
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• v.25 no.1
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• pp.9-20
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• 2015

A strainmeter goes through a period of instability immediately after installation. To determine the stability of strainmeters installed around the Andong fault zone, South Korea, an x-MR control chart analysis and a T² control chart analysis were conducted. The x-MR control chart analysis used an empirically determined 3σ control limit line to identify abnormal data in recently installed strain gauges. In the T² control chart analysis, the control limit line was set at a confidence of 95%. A comparison of the early stage of measurement with the terminal stage of measurement for three months after installation indicates that stabilization depends on the location and direction of each strain gauge in x-MR control chart analysis. In the T² control chart analysis, the number of values exceeding the control limit line decreased as the terminal stage was approached. Based on these results, it is suggested that the 3σ control limit line of an x-MR control chart can be used as a standard for single gauge stability, and that the 95% confidence limit of a T² control chart analysis could be used as the standard for the stability of multi-gauge strainmeters.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.38 no.7
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• pp.493-502
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• 2001

This paper propose a new built-in current sensor(BICS) for current testing that has some advantages compared with conventional logic testing. The designed BICS detects the fault in circuit under test (CUT) and makes a Pass/Fail signal by comparison between CUT current and duplicated inverter current. The proposed circuit consists of a differential amplifier, a comparator and a inverter. It requires 10 MOSFETs and 3 inverters. Since the designed BICS do not require the extra clock, the added extra pin is only one output pin. The mode selection is not used in this circuit. Therefore we can apply the circuit to on-line testing. The validity and effectiveness are verified through the HSPICE simulation of circuits with defects. When CUT is a 8$\times$8 parallel multiplier, area overhead of the BICS is about 4.34%.

• The Journal of Engineering Geology
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• v.8 no.3
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• pp.285-296
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• 1998

As a part of the study for understanding the deep geological structure of the Ogcheon Zone, both gravity and geomagnetic surveys are performed. A 70km survey line of which direction is nearly perpendicular to major faults in the southern tip of the Zone. The observed data are corrected and transformed into Bouguer and total magnetic intensity anomalies, respectively. Recent studies for petrology and geochemistry in the southwestern Ogcheon Zone in the vicinity of the survey line are reviewed for better interpretation. Both gravity and geomagnetic anomalies abruptly change around Janghung area, the southern boundary of the, Ogcheon Zone. This rapid increase of Bouguer anomaly around Janghung area can be explained by a deep seated normal fault with fairy large displacement between Precambrian gneisses and the denser intermediate plutonic rocks. It is believed that the fault acted an important role for the formation and evolution of the Ogcheon Zone. A pseudomagnetic intensity anomaly is calculated from the Bouguer anomaly assuming that the both anomalies are associated with the common source. From the origin of the survey line to the 50km point, the calculated anomaly coincides with observed magnetic anomaly. Whereas both anomalies show negative correlation in the outside 50km. From the residual Bouguer anomalies, the subterranean geological structure is provided through the iterative forward method. The initial model is obtained from informations about the surface geology as well as the results of the inverse method.

• The Korean Journal of Petroleum Geology
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• v.2 no.2 s.3
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• pp.59-70
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• 1994

The Cenozoic geological structures and the tectonic evolution of the southern Ulleung Basin were studied with seismic profiles and exploration well data. Basement structure of the Korea Strait is distinctly characterized by normal faults trending northeast to southwest. The normal faults of the basement are most likely related to the initial liking and extensional tectonics of Ulleung Basin. Tsushima fault along the west coast of Tsushima islands runs northeastward to the central Ulleung Basin. The Middle Miocene and older sequences in the Tsushima Strait show folds and faults mostly trending northeast to southwest. These folds and faults may be interpreted as a result of compressional tectonics. The Late Miocene to Qauternary sequences are not much deformed, but numerous faults mostly N-S trending are dominated in the Tsushima Strait. The Ulleung Basin was in intial rifting during Oligocene, and then active extension and subsidence from Early to early Middle Miocene. Therefore SW Japan separated from Korea Peninsula and drifted toward southeast, and Ulleung Basin was formed as a pull-apart basin under dextral transtensional tectonic regime. During rifting and extensional stage, Tsushima fault as a main tectonic line separating SW Japan block from the Korean Peninsula acted as a normal faulting with right-lateral strike-slip motion as SW Japan drifted southeastward. During middle Middle Miocene to early Late Miocene, the opening of Ulleung basin stopped and uplifted due to compressional tectonics. The southwest Japan block converging on the Korean Peninsula caused compressional stress to the southern margin of Ulleung Basin, resulting in strong deformation under sinistral transpressional tectonic regime. Tsushima fault acted as thrust fault with left-lateral strike-slip motion. From middle Late Miocene to Quaternary, the southern margin of Ulleung Basin has been controlled by compressional motion. Thus the Tsushima fault still appears to be an active thrust fault by compressional tectonic regime.

• Transactions on Electrical and Electronic Materials
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• v.10 no.2
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• pp.53-57
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• 2009

In this paper we develop a method to observe faults in semiconductor devices and transmission lines by calculating the variation of the reflection function in a dielectric microstrip line that has an open-ended termination containing an optically induced plasma region. It is analyzed with the assumption that the plasma is distributed homogeneously in laser illumination. With the non linear material of degradation, the concentration of the carrier in the part of the material has changed. Since the input wave has produced the phenomenon of reflection, the input signal to the open-ended microstrip lines can be observed on reflection to identify the location of the fault. The characteristic impedances resulting from the presence of plasma are evaluated by the transmission line model. The variation of the reflection wave in the microwave system has been calculated by using an equivalent circuit model. The transient response has been also evaluated theoretically for changing the phase of the variation in the reflection. The variation of characteristic response in differentially localized has been also evaluated analytically.

• Proceedings of the IEEK Conference
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• 2004.06b
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• pp.343-346
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• 2004

This paper proposes a leakage-suppressed SRAM with dynamic power saying scheme for the future leakage-dominant sub-70-nm technology. By dynamically controlling the common source-line voltage ($V_{SL}$) of sleep cells, the sub-threshold leakage through these sleep cells can be reduced to be 1/10-1/100 due to the reverse body-bias effect, dram-induced barrier lowering (DIBL) and negative $V_{GS}$ effects. Moreover, the bit-ling leakage which mar introduce a fault during the read operation can be completely eliminated in this new SRAM. The dynamic $V_{SL}$ control can also reduce the bit-line swing during the write so that the dynamic power in write can be reduced. This new SRAM was fabricated in 0.35-${\mu}m$ CMOS process and more than $30\%$ of dynamic power saying is experimentally verified in the measurement. The leakage suppression scheme is expected to be able to reduce more than $90\%$ of total SRAM power in the future leakage-dominant 70-nm process.

• Journal of KSNVE
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• v.11 no.1
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• pp.125-131
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• 2001

There is a clearance between the parts of a machine due to design tolerance, manufacturing error, wear, looseness, or misalignment. If the clearance is large, the vibration and noise of the machine is generally large. Therefore, the analysis on the nitration and noise of a machine can tell the clearance of the machine, which reveals the condition of the machine, i.e., the existence of faults and the safety of the machine. The investigation of this kind of research should be on the basis of experimental results. A link mechanism with a clearance at a joint between the coupler and locker is made for the investigation of the condition monitoring of a machine due to clearance. The vibration and sound are measured from the link driving system during the operation. The signals are clarified using line enhancement technique. The noise removed signals are used to develop the dynamic model of the system for a model based fault diagnosis. Also this study showed that the clarified signals can be used for the calculation of the joint forces between the coupler and rocker and for the correlation between the vibration and sound levels and the clearance sizes.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.6
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• pp.29-35
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• 2005

This paper presents the basic quench protection idea for the HTS(High-Temperature Superconducting) cable. In Korea power system, the transfer capability of transmission line is limited by the voltage stability, HTS cable could be one of the countermeasure to enhance the transfer limit with its higher current capacity and lower impedance[1]. However, the quench characteristic makes not only HTS cable to loss its superconductivity, but also change the impedance of the transmission line and power system operating condition dramatically. This pheonominum threats HTS cable safety as well as power system security, therefore a proper protection scheme and security control counterplan have to be established before HTS cable implementation. In this paper, the quench characteristics of HTS cable for the fault current based on heat balance equation was established and a proper protection method regarding conventional protection system was suggested.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.6
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• pp.857-863
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• 2015

OF cable with excellent reliability and economic efficiency, has been used as the main cable of underground transmission in Korea. However, as XLPE cable is excellent in view points such as reduction of loss, convenience on the construction/operation, and manufacturing technology, it has been replaced as instead of OF cable. Also, when the aging occurs in some sections of OF cable, the section is replaced as XLPE cable without changing of whole cable line. However, there are some differences like electrical constants between both types of cables. Therefore if underground transmission system will be operated as combined connection composited of both cables, it should be proved that overvoltage is stable in steady and transient state. This paper describes the effectiveness of connection operation in combined OF and XLPE cable. For the evaluation of effectiveness, some important analysis such as sheath component voltage, lightning and switching overvoltage, single line-to-ground fault are carried out in steady and transient state. EMTP/ATPDraw is used for modeling and analysis of system.

• Journal of Electrical Engineering and Technology
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• v.10 no.3
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• pp.1093-1101
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• 2015

Partial Discharge (PD) is a physical phenomenon, which causes defects and damages to the insulation. This phenomenon is regarded as the most important source of fault and defect in power transformers. Therefore, methods of high speed and precision are considered of special importance for the maintenance of transformers in localization of the origin of partial discharge. In this paper, the transformer winding is first modeled in a transient state by using RLC ladder network and multiconductor transmission line (MTL) models. The parameters of the two models were calculated by Ansoft Maxwell software, and the simulations were performed by Matlab software. Then, the PD pulses were applied to the models with different widths of pulses. With regard to the fact that the signals received after the application of PD had a variable frequency nature over time, and based on the wavelet transform and signal energy, a new method was presented for the localization of PD. Ultimately; the mentioned method was implemented on a 20 kV winding distribution transformer. Then, the performances of the models used in this paper, including RLC and MTL models, were compared in different frequency bands for the correct distinction of partial discharge location.