• Corrosion Science and Technology
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• v.13 no.3
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• pp.112-119
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• 2014

In this work, it is aimed to develop the fabrication method of axial stress corrosion cracking (SCC) defects having various sizes, on the outer diameter surface of the steam generator (SG) tubings. To control the length of the artificial SCC defect, the specific area of the SG tubing samples was exposed to an acidic solution after a sensitization heat treatment. During the exposure to an acidic solution, a direct current potential drop (DCPD) method was adopted to monitor the crack depth. The size of the SCC defect was first evaluated by an eddy current test (ECT), and then confirmed by a destructive examination. From the comparison, it was found that the actual crack length was well controlled to be similar to the length of the surface exposed to an acidic solution (5, 10, 20 or 30 mm in this work) with small standard deviation. From in-situ monitoring of the crack depth using the DCPD method, it was possible to distinguish a non-through wall crack from a through wall crack, even though the depth of the non-through wall crack was not able to be precisely controlled. The fabrication method established in this work was useful to simulate the SCC defect having similar size and ECT signals as compared to the field cracks in the SG tubings of the operating Korean PWRs.

• Journal of Magnetics
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• v.18 no.3
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• pp.342-347
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• 2013

Local wall thinning in pipelines affects the structural integrity of industries, such as nuclear power plants (NPPs). In the present study, a development of pulsed eddy current (PEC) technology that detects the wall thinning of pipelines covered with insulation is reviewed. The methods and experimental results, which have two kinds of probe with a single and double core, were compared. For this purpose, the single and double core probes having one and two excitation coils have been devised, and the differential probe with two Hall sensors has been fabricated to measure the wall thinning in insulated pipelines. The test sample is a stainless steel having different thickness, laminated by plastic insulation to simulate the pipelines in NPPs. The excitation coils in the probe is driven by a rectangular current pulse, the difference of two Hall sensors has been measured as a resultant PEC signal. The peak value of the detected signal is used to describe the wall thinning. The double core probe has better performance to detect the wall thinning covered with insulation; the single core probe can detect the wall thinning up to an insulation thickness of 18 mm, whereas the double probe can detect up to 25 mm. The results show that the double core PEC probe has the potential to detect the wall thinning in an insulated pipeline of the NPPs.

• The Journal of Asian Finance, Economics and Business
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• v.5 no.1
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• pp.53-62
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• 2018

The study aims to conduct organizational diagnosis at Infosys and to suggest measures of improvement of the same wherever necessary. Data was collected with the help of a structured questionnaire. Respondents were selected with the help of random sampling technique. The sample size is 19. The employees are not much clear about their goals and the purpose of the organization. The employees are not satisfied with the current structure and the division of the work in the organization, and also with the current reward mechanism of the organization. However the employees are satisfied with their leaders and their leadership styles. The employees feel that they share a good relationship with their peers. The employees of Infosys have full confidence in the management and they believe that the management is helping them in their career growth. Some of the interventions suggested are as follows: Role Analysis Technique can be used so that the employees get clarity of their goals. As the score suggests that the employees are not happy with the current structure and distribution of the work, mentors can be assigned to the employees who can guide them and can also help the employees to understand the structure and processes better.

• Journal of Physiology & Pathology in Korean Medicine
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• v.27 no.1
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• pp.112-117
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• 2013

We studied the modulation of pacemaker activities by Samchulkunbi-tang (SCKB) in cultured interstitial cells of Cajal (ICC) from murine small intestine with the whole-cell patch-clamp technique. Externally applied SCKB produced membrane depolarization in the current-clamp mode. The pretreatment with $Ca^{2+}$-free solution and thapsigargin, a $Ca^{2+}$-ATPase inhibitor in endoplasmic reticulum, abolished the generation of pacemaker potentials and suppressed the SCKB-induced action. The application of flufenamic acid (a nonselective cation channel blocker) abolished the generation of pacemaker potentials by SCKB. However, the application of niflumic acid (a chloride channel blocker) did not inhibit the generation of pacemaker potentials by SCKB. In addition, the membrane depolarizations were inhibited by not only GDP-${\beta}$-S, which permanently binds G-binding proteins, but also U-73122, an active phospholipase C inhibitor. These results suggest that SCKB modulates the pacemaker activities by nonselective cation channels and external $Ca^{2+}$ influx and internal $Ca^{2+}$ release via G-protein and phospholipase C-dependent mechanism. Therefore, the ICC are targets for SCKB and their interaction can affect intestinal motility.

• Mass Spectrometry Letters
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• v.1 no.1
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• pp.17-20
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• 2010

As background significantly affects measurement accuracy and a detection limit in determination of the trace amounts of uranium, it is necessary to minimize the impurities in the filaments used for thermal ionization mass spectrometry (TIMS). We have varied the degassing condition such as the heating currents and duration times to reduce the backgrounds from the filaments prepared with zone-refined rhenium tape. The most efficient degassing condition of the heating current and the duration time was determined as 3.5 A and 60 min, respectively. The TIMS measurement combined with the isotope dilution mass spectrometry (IDMS) technique showed that the uranium backgrounds were determined to be in a few fg level from blank rhenium filaments. The background minimized filaments were utilized to measure the uranium isotope ratios of a U030 (NIST) standard sample. The excellent agreement of the measurement with the certified isotope ratios showed that the degassing procedure optimized in this study efficiently reduced the impurity signals of uranium from blank rhenium filaments to a negligible level.

• Journal of Communications and Networks
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• v.10 no.3
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• pp.239-252
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• 2008

For orthogonal frequency division multiplexing (OFDM), cyclic prefix (CP) should be longer than the length of channel impulse response, resulting in a loss of bandwidth efficiency. In this paper, we describe a new technique to restore the cyclicity of the received signal when the CP is not sufficient for OFDM systems. The proposed technique efficiently restores the cyclicity of the current received symbol by adding the weighted next received symbol to the current received symbol. Iterative CP reconstruction (CPR) procedure, based on the residual intersymbol interference cancellation (RISIC) algorithm, is analyzed and compared to the RISIC. In addition, we apply the CPR method to Alamouti space-time block coded (STBC) OFDM system. It is shown that in the STBC OFDM, tail cancellation as well as cyclic reconstruction of the CPR procedure should be repeated. The computational complexities of the RISIC, the proposed CPR, the RISIC with STBC, and the proposed CPR with STBC are analyzed and their performances are evaluated in multipath fading environments. We also propose an iterative channel estimation (CE) method for OFDM with insufficient CP. Further, we discuss the CE method for the STBC OFDM system with the CPR. It is shown that the CPR technique with the proposed CE method minimizes the loss of bandwidth efficiency due to the use of CP, without sacrificing the diversity gain of the STBC OFDM system.

• Proceedings of the KIPE Conference
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• 2008.06a
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• pp.413-415
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• 2008

The charge equalizer design for a series connected battery string is very challenging because it needs to satisfy many requirements such as implementation possibility, equalization speed, equalization efficiency, controller complexity, size and cost issues, voltage and current stress, and so on. Numerous algorithms and circuits were developed to meet the above demands and some interesting results have been obtained through them. However, for a large number of cells, for example, eighty or more batteries, the previous approaches might cause problems. Such problems include long equalization time, high controller complexity, bulky size, high implementation cost, and high voltage and current stress. To overcome these circumstances, this paper proposes a charge equalizer design method based on a battery modularization technique. In this method, the number of cells that we consider in an equalizer design procedure can be effectively reduces; thus, designing a charge equalizer becomes much easier. Furthermore, by applying the previously verified charge equalizers to the intramodule and the outer-module, we can obtain easy design of a charge equalizer and good charge balancing performance. Several examples and experimental results are presented to demonstrate the usefulness of the charge equalizer design method.

• Progress in Superconductivity and Cryogenics
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• v.15 no.2
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• pp.12-15
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• 2013

The pure and carbon (C)-doped $MgB_2$ thin films were fabricated on $Al_2O_3$ (0001) substrates at a temperature of $650^{\circ}C$ by using hot-filament-assisted hybrid physical-chemical vapor deposition technique. The $T_c$ value for pure $MgB_2$ film is 38.5 K, while it is between 30 and 35 K for carbon-doped $MgB_2$ films. Expansion in c-axis lattice parameter was observed with increase in carbon doping concentration which is in contrast to carbon-doped $MgB_2$ single crystals. Significant enhancement in the critical current density was obtained for C-doped $MgB_2$ films as compared to the undoped $MgB_2$ film. This enhancement is most probably due to the incorporation of C into $MgB_2$ and the high density of grain boundaries, both help in the pinning of vortices and result in improved superconducting performance.

• Journal of The Korean Digital Architecture Interior Association
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• v.3 no.1
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• pp.39-49
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• 2003

The height provisions, by the urban planning, describe the hightest height per width division, also define oblique line limitation by road without mentioning the highest per width division. Therefore this study will be a basic model for the standard of measuring the highest height per width division analysizing the propriety of current standard of oblique limitation. This technique is prepared to prevent the confusion and to complements the existing planning method. Therefore, it takes more time to establish this new method and to apply it to the existing condition. This study reviewed density control in District Units Plan, based on the guidelines of density, which included height, ratio of total floor to ground area, and land distribution. This study aims to provide efficient analysis by using current oblique limitation provisions Thus, proving the area rations of general residential areas are decreasing. Since the purpose of the District Units Plan is to avoid confusion and help ease the existing problematic conditions which have risen from the two above-mentioned conventional systems, further observation and research on these areas are necessary.

• Proceedings of the KIPE Conference
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• 2007.07a
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• pp.435-437
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• 2007

Authors propose a PFC(power factor correction) Buck-Boost AC-DC converter by soft switching method. The proposed converter for a discontinuous conduction mode eliminates the complicated control requirement and reduces the size of components. The input current waveform in the converter is got to be a sinusoidal form of discontinuous pulse in proportion to magnitude of ac input voltage under the constant duty cycle switching.Therefore,the input power factor is nearly unity and the control algorithm is simple. To achieve high efficiency system, the proposed converter is constructed by using a partial resonant technique. The control switches using in the converter are operated with soft switching for a partial resonant. The control switches are operated without increasing their voltage and current stresses by the soft switching method. The result is that the switching loss is very low and the efficiency of converter is high.