• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.591-592
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• 2006

We studied about the manufacture of the drain-source contacts for OTFTs(organic thin-film transistors) by using screen printing method. The conductive fillers used Ag and carbon black. The conductive contacts with $100{\mu}m$ of channel length were screen printed on a silicon dioxide gate dielectric layer and, the pentacene semiconductor was deposited via vacuum deposition. As a result of studying various conductive pastes, we could obtain the OTFTs which exhibited field-effect behavior over arrange of drain-source and gate voltages, similar to devices employing deposited Au contacts. By using screen-printing with conductive paste, the contacts are processed at low temperature, thereby facilitating their integration with heat sensitive substrates.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.34 no.4
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• pp.135-143
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• 1985

The failure and erosion of relay contacts mainly depend on the presence of particles deposited on the contact surface in various contaminated atmospheres. In this paper, the effects of sea water and circuit parameters on the arcing and quenching of magnet relay contacts are studied. The sea water pollutants of relay contact surface have led to increase the arcing numbers on making contact, and the mean arc durations on breaking contacts. Moreover, the maximum surge voltage and mean arc duration between relay contacts are also varied significantly by the circuit parameters. The effects of the spark quenching circuits using condenser of diode on the arcing of contacts are also discussed.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.51 no.2
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• pp.55-61
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• 2002

In this paper, 'lifetime-temperature rise model' based on the 'lifetime-resistance model' is theoretically Proposed, in order to find out the evaluation method of degradation and the residual lifetime by use of infrared image camera for electric connections/contacts. Two assumptions have been builded up for the 'lifetime-temperature rise model': one is associated with the linear relationship between the temperature ism ΔK and contact resistance, and the other the functional relationship between the temperature of electric connections/contacts and the operating time presenting in the 'lifetime-resistance model'. To prove the proposed model, experiments have been performed for various electric connections/contacts. From the experimental results, measured values were quite similar to the calculated values, which proved the above-mentioned two assumptions. Therefore, by use of 'lifetime-temperature rise model', it is possible to estimate the trend of degradation and the residual lifetime for electric connections/contacts through the temperature measurements .

• The Journal of Advanced Prosthodontics
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• v.7 no.6
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• pp.431-436
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• 2015

PURPOSE. The aim of this study was to evaluate occlusal contacts generated by 3 different biogeneric design modes (individual (BI), copy (BC), reference (BR)) of CEREC software and to assess the designs subjectively. MATERIALS AND METHODS. Ten pairs of maxillary and mandibular casts were obtained from full dentate individuals. Gypsum cast contacts were quantified with articulating paper and digital impressions were taken. Then, all ceramic crown preparation was performed on the left first molar teeth and digital impressions of prepared teeth were made. BI, BC, and BR crowns were designed. Occlusal images of designs including occlusal contacts were superimposed on the gypsum cast images and corresponding contacts were determined. Three designs were evaluated by the students. RESULTS. The results of the study revealed that there was significant difference among the number of contacts of gypsum cast and digital models (P<.05). The comparison of the percentage of virtual contacts of three crown designs which were identical to the contacts of original gypsum cast revealed that BI and BR designs showed significantly higher percentages of identical contacts compared with BC design (P<.05). Subjective assessment revealed that students generally found BI designs and BR designs natural regarding naturalness of fissure morphology and cusp shape and cusp tip position. For general occlusal morphology, student groups generally found BI design "too strong" or "perfect", BC design "too weak", and BR design "perfect". CONCLUSION. On a prepared tooth, three different biogeneric design modes of a CAD/CAM software reveals different crown designs regarding occlusal contacts and morphology.

• Tuberculosis and Respiratory Diseases
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• v.82 no.4
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• pp.298-305
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• 2019

Background: Tuberculosis (TB) causes substantial health burden to the Korean military. This study aims to assess the impact of infectious TB cases on close and casual contacts in the Korean Army settings based on contact investigation data. Methods: Six Army units with infectious TB cases from September 2012 to May 2013 were enrolled in the study. We analyzed the clinical data from close and casual contacts screened using the tuberculin skin test (TST) and QuantiFERON-TB Gold In-Tube to identify latent tuberculosis infection (LTBI) cases. For the control group, 286 military conscripts with no reported TB exposure were tested by TST only. Results: Of the 667 contacts of index cases, LTBI cases identified were as follows: 21.8% of close contacts of smearpositive cases (71/326), 8.5% of casual contacts of smear-positive cases (26/305), and 2.8% of close contacts of smearnegative cases (1/36). In the control group, 16.8% showed positivity in TST. In a multivariate analysis, having stayed in the same room or next room with TB patients was identified as a risk factor of LTBI. Conclusion: Using the data from TB contact investigations in the Korean Army units, we found an overall LTBI rate of 14.7% among the contacts screened. This study demonstrates that contacts living in the same building, especially the same room or next room, with TB patients are at a high risk of acquiring LTBI, serving as additional evidence for defining close and casual contacts of a TB patient with regard to Army barrack settings.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.1
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• pp.46-51
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• 2008

Extra-high voltage(EHV) disconnecting switch(DS) consists of the electrical contacts and mechanical parts which actuate the contacts. When the short-circuit condition occurs, a large amount of current flows through the electrical contact in disconnecting switches and this causes considerable temperature rise due to Joule heating. If the temperature rise is higher than the melting point of contact material, the DS contact becomes melting and cannot be usable anymore. For this reason, the analysis for capability of carrying short-circuit current in DS contacts must be performed at a design stage. Here, we proposed a numerical technique for evaluating the capability of carrying short-circuit current at electrical contacts in EHV DS. In this numerical approach, the mechanical and thermal analyses were simulated to check the capability of carrying short-circuit current. First, the applied pressure at contact parts was analyzed considering the mechanical properties, and then contact resistance was calculated by an empirical equation. Finally, thermal analysis was performed with resistance variation at electrical contacts. To verify these numerical results, the distributions of temperature in DS were experimentally measured and compared with each other. The results from experiments were agreed well with those from the proposed numerical simulations.

• Child Health Nursing Research
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• v.26 no.4
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• pp.393-401
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• 2020

Purpose: This pilot study aimed to describe children's social contact patterns and to analyze factors related to their social contacts. Methods: The participants were 30 children aged ≥13 months to <7 years, whose teachers at childcare centers and parents at home were asked to maintain diaries of their social contacts prospectively for 24 hours. Data were collected from November 30, 2018, to January 7, 2019. Results: The 30 participating children were in contact with 363 persons in a 24-hours period (mean, 12.1±9.1). The number of contacts showed significant relationships with day of the week (p<.001), number of family members/cohabitants (p=.015), area of residence (p=.003), and type of housing (p=.002). A multiple regression model showed significantly higher numbers of contacts on weekdays (B=10.64, p=.010). Physical versus non-physical types of contact showed significant differences in terms of duration, location, and frequency (p<.001). The duration of contacts showed significant relationships with their location and frequency (p<.001), while the frequency of contacts was significantly related to their location (p<.001). Conclusion: This is the first survey describing the characteristics of Korean preschool children's social contacts. Further large-scale social contact studies of children should be conducted.

• Korean Journal of Child Studies
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• v.17 no.2
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• pp.107-119
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• 1996

This study investigated social competence, peer contacts, and emotional development in children of lower SES employed mothers. Instruments were Choi's (1992) questionnaire on social competence, Pettit's (1988) questionnaire on peer contacts, and Kang's (1986) and Kim's (1993) questionnaires on emotional development. The data was analyzed by t-test. Social class differences were found in children's social capability, leadership and anxiety, in peer contacts, and in emotional disturbance and aggression.

• The Journal of Korean Academy of Prosthodontics
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• v.53 no.2
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• pp.128-137
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• 2015

Purpose: Most of the former studies about the occlusal contact patterns during the mandibular movement focused on foreigner. The purpose of this study is analyzing the occlusal contacts of young Koreans by using T-Scan system. Materials and methods: The sample size was 87 and the occlusal contacts of each right and left lateral movements were measured from the maximum intercuspation to the 3mm excursive position for three times respectively. All of the occlusal contacts were double checked through the thin metal foil. The results were categorized as two; 1) considering occlusal contact patterns on working side only, 2) considering occlusal contact patterns on working and nonworking sides. Results: The results showed that the nonworking side occlusal contacts play major roles in the lateral mandibular movement. In both cases of considering with and without the nonworking side occlusal contacts, the group function was the most prevalent. In the working side, the contacts were the most frequent in canine and the frequency of contacts was decreased as the distance was increased from canine to molar. In the nonworking side, the contacts were the most frequent in second molar. And the gender factor was statistically significant (${\alpha}$=.05), as females have more nonworking side occlusal contacts in this study. Conclusion: Among the three factors of anterior guidance, the group function was the most dominant factor. The analysis of 87 samples showed that canine contact was the most frequent in the working side and second molar contact was the most common in the nonworking side.

• Journal of Medicine and Life Science
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• v.17 no.1
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• pp.29-32
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• 2020

As respiratory syncytial virus(RSV) is transmitted either via directly contact with an infected case or via indirectly contaminated fomites or skin, the major preventive measures are strict hand hygiene, early detection of transmitted sources, and rapid isolation of RSV patients. Especially early detection of hidden cases is the most critical control measure when an index case was notified in a postpartum center. The Guideline of Korea Centers for Diseases Control and Prevention defines potential contacts in an epidemiologic survey as admitted newborns, parents of index cases, center's workers, and visitors for 10 days before the first diagnosis day of index case. However, it needs to classify potential contacts in more detail in order to conduct a successful survey. Authors conducted to search related literatures and appraise the evidences. Firstly, potential contacts would be classified into RSV-related symptomatic contacts(SxC) and asymptomatic contacts. And then, mother, caring workers, and visitors of the index cases among asymptomatic contacts would be defined as the asymptomatic close contacts(ASCC). Finally, the rest would be defined as the asymptomatic regular contacts(ASRC). The defined test using reverse transcription-PCR is applied to SxC and ASCC, and decision of isolation or regular activities are made according to the results. The rapid antigen detection test kits are applied to ASRC. These suggestions might be helpful to detect hidden cases earlier and prevent a further infection.