• Smart Structures and Systems
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• v.23 no.3
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• pp.279-293
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• 2019

To ensure high quality data being used for data mining or feature extraction in the bridge structural health monitoring (SHM) system, a practical sensor fault diagnosis methodology has been developed based on the similarity of symmetric structure responses. First, the similarity of symmetric response is discussed using field monitoring data from different sensor types. All the sensors are initially paired and sensor faults are then detected pair by pair to achieve the multi-fault diagnosis of sensor systems. To resolve the coupling response issue between structural damage and sensor fault, the similarity for the target zone (where the studied sensor pair is located) is assessed to determine whether the localized structural damage or sensor fault results in the dissimilarity of the studied sensor pair. If the suspected sensor pair is detected with at least one sensor being faulty, field test could be implemented to support the regression analysis based on the monitoring and field test data for sensor fault isolation and reconstruction. Finally, a case study is adopted to demonstrate the effectiveness of the proposed methodology. As a result, Dasarathy's information fusion model is adopted for multi-sensor information fusion. Euclidean distance is selected as the index to assess the similarity. In conclusion, the proposed method is practical for actual engineering which ensures the reliability of further analysis based on monitoring data.

• KEPCO Journal on Electric Power and Energy
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• v.7 no.2
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• pp.317-321
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• 2021

As the large-scale renewable energy power plant increases, the high-capacity and compact Energy Storage System (ESS) is required. However, this trend could reduce the insulation reliability of ESS. In this study, the surface flashover characteristics for four types of solid insulators are investigated in the uniform electric field with AC and Lightning Impulse (LI) voltage waveforms under various contamination levels. In addtion, insulator surfaces are compared based on the contact angle before and after surface flashover. The experimental results show that AC flashover voltage is dependent on the materials and the contamination level, but LI flashover voltage is only associated with the contamination level. Especially, AC flashover voltage of PC (PolyCarbonate) is higher than that of other insulators, which is associated with the unique and sequential creepage discharge propagation pattern of PC. The localized discharges on the surface of PC form corresponding tracking points. Then, the interconnected trackings result in the complete flashover. This flashover patterns degrade the surface of PC much more than that of epoxy and Bulk Molding Compoud (BMC). Thus, the contact angle of PC is significantly reduced compared to that of other insulators. The increased hydrophilicity in the surface of PC enhances the insulator surface conductivity.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.35 no.3
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• pp.246-254
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• 2022

Localized heat can be generated using electrically conductive word-lines built into a 3D NAND flash memory string. The heat anneals the gate dielectric layer and improves the endurance and retention characteristics of memory cells. However, even though the electro-thermal annealing can improve the memory operation, studies to investigate material failures resulting from electro-thermal stress have not been reported yet. In this context, this paper investigated how applying electro-thermal annealing of 3D NAND affected mechanical stability. Hot-spots, which are expected to be mechanically damaged during the electro-thermal annealing, can be determined based on understanding material characteristics such as thermal expansion, thermal conductivity, and electrical conductivity. Finally, several guidelines for improving mechanical stability are provided in terms of bias configuration as well as alternative materials.

• Corrosion Science and Technology
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• v.22 no.3
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• pp.153-163
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• 2023

Two types of accelerated tests, Water Drop Test (WDT) and Temperature-Humidity-Bias Test (THBT), can be used to evaluate the susceptibility to electrochemical migration (ECM). In the WDT, liquid water is directly applied to a specimen, typically a patterned conductor like a printed circuit board. Time to failure in the WDT typically ranges from several seconds to several minutes. On the other hand, the THBT is conducted under elevated temperature and humidity conditions, allowing for assessment of design and life cycle factors on ECM. THBT is widely recognized as a more suitable method for reliability testing than WDT. In both test methods, localized corrosion can be observed on the anode. Composition of dendrites formed during the WDT is similar to that formed during THBT. However, there is a lack of correlation between the time to failure obtained from WDT and that obtained from THBT. In this study, we investigated the relationship between electrochemical parameters and time to failure obtained from both WDT and THBT. Differences in time to failure can be attributed to actual anode potential obtained in the two tests.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.166-166
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• 2020

Recently, As the frequency of localized heavy rains increases, the use of high-resolution radar data is increasing. The produced radar rainfall has still gaps of spatial and temporal compared to gauge observation rainfall, and in many studies, various statistical techniques are performed for correct rainfall. In this study, the precipitation correction of the S-band Dual Polarization radar in use in the flood forecast was performed using the ConvAE algorithm, one of the Convolutional Neural Network. The ConvAE model was trained based on radar data sets having a 10-min temporal resolution: radar rainfall data, gauge rainfall data for 790minutes(July 2017 in Cheongju flood event). As a result of the validation of corrected radar rainfall were reduced gaps compared to gauge rainfall and the spatial correction was also performed. Therefore, it is judged that the corrected radar rainfall using ConvAE will increase the reliability of the gridded rainfall data used in various physically-based distributed hydrodynamic models.

• Journal of the Korean Geotechnical Society
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• v.39 no.7
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• pp.49-56
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• 2023

Gravel is commonly employed to enhance the bearing capacity of foundations and provide stable support for structures. However, effectively assessing the ground characteristics in the presence of gravel poses significant challenges. This study aims to compare the resolution of ground containing gravel using electrical resistivity, elastic wave surveys, and ground penetration radar (GPR). Nondestructive methods are applied at construction sites where soil improvement is carried out using gravel. The experiments focus on shallow depths, and the obtained results cover depths up to 2 m. Both the electrical resistivity and elastic wave techniques exhibit similar behavior in their findings, indicating comparable outcomes. However, GPR has limitations in observing the characteristics of ground with gravel. Dynamic cone-penetration tests were conducted to validate these findings. The electrical resistivity and elastic wave profiles exhibited similar behaviors in localized areas, further supporting their compatibility and reliability.

• Journal of the Korean Society of Food Culture
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• v.21 no.1
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• pp.65-70
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• 2006

The purpose of this study were to measure brand personalities of deluxe hotels in Seoul, and to identify the difference of brand personality between local and international hotels. The questionnaires developed for this study were distributed to 460 employees in kitchen and F&B departments of 11 deluxe hotels in Seoul. A total of 398 questionnaires were used for anaylsis(86.5%) and the statistical analyses were completed using SPSS Win(12.0) for descriptive analysis, reliability analysis and t-test, and AMOS(5.0) for confirmatory factor analysis. The results of this study showed that deluxe hotels have brand personalities relatively strong at 'affection', 'sophistication', 'competence' dimensions, and there was a significant difference by hotel nationality. The brand personality scores of international brand hotels perceived by employees were high at the 'excitement'(p<0.001), 'sophistication'(p<0.001), and 'competence'(p<0.01) dimensions, whereas local hotels were considered more obedient(p<0.01). Overall, it could be a key factor for successful brand management that establish a distinctive brand personality, and a localized brand personality measure will lead to more desirable decision making.

• Tuberculosis and Respiratory Diseases
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• v.43 no.3
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• pp.339-347
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• 1996

Background : Transthoracic fine needle aspiration and biopsy(TNAB) has become a frequently used technique in the investigation of the intrathoracic lesions because of its safety, reliability, and accuracy. Method : Data on 125 patients who underwent TNAB from 1990 through 1994 were studied to determine the diagnostic sensitivity, accuracy and complications of this procedure as related to lesion type and location. Results : 1. The over-all diagnostic sensitivity of TNAB was 61.6%(77 of 125 patients). 2. The diagnostic yields were as high as 89.9% for malignant lesions, but a specific diagnosis of benign lesions were obtained only in 30% of benign lung lesions. 3. The correlation between results of TNAB cytology and of final histology was as high as 88.2%. 4. Lung lesions that were greater than 3cm in size had a higher proportion of correct diagnosis(73.3%) as compared with lesions 3cm or less in size(38.1%). But there was no significant difference between the central and peripheral lung lesions. 5. There were no serious complications to TNAB. In 12.8% of the procedures a pneumothorax developed, indicating a chest tube in 1.6% of the procedures. In 2 cases, minimal hemoptysis developed which did not require treatment. Conclusion : In our experience, TNAB represents a minor and safe procedure, which permits a direct approach to localized malignant lung lesions with a high degree of accuracy.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.11 no.1
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• pp.70-78
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• 2000

This study was to develop Korean version of Parenting Stress Scale. Primary research was processed thru Abidin's PSI(Parenting Stress Index) scale. For the pilot primary study, distri-buted questionnaire to the mothers who have three to twelve age children and tried factor analysis with 382 data sheets. At the result, 29 items and 5 factors among the 47 items of child domain, 28 items and 5 factors among the items of parent domain were extracted. At the secondary pilot study survey, reanalyzed the 57 items extracted by primary pilot survey with the 392 data collected from three to six age children's parents. For the item discrimination analysis, calculated item-total correlation and deleted the items under r=.20. For the validity test, reviewed content validity and construct validity. For the verification of construct validity, tried factor analysis. At the result, in child domain area, the four factors, 'Reinforces Parent's, 'Accep-tability', 'Attention Distractiveness', 'Demandingness' and 24 items were extracted. Among the common variance of child domain, 'explained common variance' was 82.05%. In parent domain area, the five factors, 'Restriction of Role', 'Depression', 'Social Isolation', 'Parent Health', 'Spouse Relationship' and 24 items were extracted. Among the common variance of parent domain, 'explained common dominator' was 82.40%. For the verification of reliability, Cronbach's ${\alpha}$ coefficient was calculated and in child domain, .69, .70, .67, .66 were produced by each item, respectively and total reliability coefficient was ${\alpha}$=.81. Reliability coefficient of parent domain was .73, .70, .70, .55, .73 by each item, respectively and total reliability coefficient was ${\alpha}$=.83. This study was processed as a primary research to develop the Korean version of parent stress scale which is originally from U.S.A. version of PSI and apply it to proper Korean culture. Therefore, the necessity of continuous study was discussed with more localized items and factors.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.128.1-128.1
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• 2016

Nitrided-metal gates on the high-${\kappa}$ dielectric material are widely studied because of their use for sub-20nm semiconductor devices and the academic interest for the evanescent states at the Si/insulator interface. Issues in these systems with the Si substrate are the electron mobility degradation and the reliability problems caused from N defects that permeates between the Si and the $SiO_2$ buffer layer interface from the nitrided-gate during the gate deposition process. Previous studies proposed the N defect structures with the gap states at the Si band gap region. However, recent experimental data shows the possibility of the most stable structure without any N defect state between the bulk Si valence band maximum (VBM) and conduction band minimum (CBM). In this talk, we present a new type of the N defect structure and the electronic structure of the proposed structure by using the first-principles calculation. We find that the pair structure of N atoms at the $Si/SiO_2$ interface has the lowest energy among the structures considered. In the electronic structure, the N pair changes the eigenvalue of the silicon-induced gap state (SIGS) that is spatially localized at the interface and energetically located just above the bulk VBM. With increase of the number of N defects, the SIGS gradually disappears in the bulk Si gap region, as a result, the system gap is increased by the N defect. We find that the SIGS shift with the N defect mainly originates from the change of the kinetic energy part of the eigenstate by the reduction of the SIGS modulation for the incorporated N defect.