• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.699-701
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• 2003

This paper compare the Townsend theory with the Molten metal bridge theory of Holm for the arc discharge at opening contacts. And we measured the arc voltage at opening contacts of the 3 types arc extinction unit used in DC magnetic contactor. So, we sure that the molten metal bridge contributes to form the arc. By the experiment of the 3 types arc extinction unit, we know that the magnetic force acting on the arc doesn't effect forming arc but contribut the arc extinction.

• Proceedings of the KIEE Conference
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• 2006.07e
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• pp.37-38
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• 2006

In this paper, the fire characteristics of circuit breakers for low voltage during switching arcs were analyzed according to the characteristics of combustible materials. Arc dispersion and ignition process were taken by high speed imaging system and digital camera. In this experiment, four resistors were connected as loads. To discover the fire characteristics of circuit breakers by combustible materials, ethanol and cotton were installed as combustibles near contacts respectively. In case of ethanol, fire broke out near the contacts while switch was turned on and turned off. Whereas, in case of cotton, fire broke out near deteriorated contacts while switch was turned off.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.966-968
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• 2005

Generally the high-voltage and high-current making switch is used to test the short-circuit test. The making switch should be operated always same speed/time and kept electrical-mechanical characteristic. There are spring charge type, hydro-pneumatic type and compressed air type etc. according to operation method of making switch contacts. Especially the making switch contacts of hydro-pneumatic type are moved by actuator and accumulator. To keep same speed/time of contacts and characteristic of making switch, actuator and accumulator should be worked always uniformly. So the dynamic analysis of actuator and accumulator of hydro-pneumatic type making switch will be helpful to maintain and design.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.2
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• pp.184-190
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• 2009

One of the purposes of arc control is to change its state to the diffuse state before current zero as soon as possible. This can provide optimal conditions for full extinction of arc by minimizing the quantity of residual plasma between contacts near current zero. TRV(transient recovery voltage) occurs at current zero at the same time with current interruption. If there is substantial residual plasma near current zero it can cause 'post arc current' by the interaction of its conductance with TRV. In this paper, arc control ability as a function of configuration of spiral type VI contacts was compared on the criteria of the time taken for arc to reach to the diffuse state.

• Pediatric Infection and Vaccine
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• v.22 no.2
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• pp.91-96
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• 2015

Purpose: The study aimed to determine data collected during tuberculosis (TB) contact investigations and to evaluate the outcomes of these investigations. Methods: We reviewed medical records for child contacts of patients with culture-positive pulmonary TB aged 19 years or older between August 2012 and July 2014. Results: A total of 116 child contacts were identified for 79 patients with culture-positive pulmonary TB. Of 116 contacts identified, 22% were incompletely screened. Of 90 contacts who completed screening, 42% had negative tuberculin skin test (TST) results, 58% had positive results, and 1% had active pulmonary TB at the time of investigation. Of 50 contacts with TB patients with a negative smear, 50% had positive TST results. Age ${\geq}5$ years (OR 8.3; 95% CI 2.3-30) and male gender (OR 3.9; 95% CI 1.5-9.9) were significantly associated with being incompletely screened. Conclusions: Improvement is needed in the process of contact investigations to ensure that contacts of patients with active pulmonary TB are identified and appropriately screened.

• Pediatric Infection and Vaccine
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• v.22 no.1
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• pp.7-15
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• 2015

Purpose: The purpose of this study is to investigate secondary infections within the households of newly diagnosed tuberculosis patients. Methods: We collected data on household infections of tuberculosis patients by retrospective review of medical records and telephone surveys. Results: Out of 321 newly diagnosed tuberculosis cases, a total of 253 patients who received telephone surveys were enrolled in this study. Less than 50% of the patients had household contacts screened for tuberculosis infection, and most of the patients were not aware of the necessity of testing. Out of 562 household contacts, there were 8 cases of secondary tuberculosis (1.4%, 8/562) in 7 households. There were 15 cases of latent infection (2.7%, 15/562) in 13 households. Out of 110 child and adolescent household contacts, there were no cases of secondary tuberculosis, and there were 8 cases of latent infection (7.3%) in 7 households, which was 20.5% among child and adolescent contacts screened for tuberculosis infection. In 3 of the cases (13.0%) that had secondary tuberculosis or latent infection in their households, the source of infection was extrapulmonary tuberculosis. There was no correlation between the frequency of household infections and the presence of pulmonary cavities, sputum AFB smear results, and microbiologically confirmed results. Conclusions: For effective investigation of tuberculosis contacts, it is necessary to raise general awareness on the necessity of investigating household contacts, and there should also be a continued assessment on tuberculosis contact investigation since government-supported programs.

• Tuberculosis and Respiratory Diseases
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• v.78 no.4
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• pp.349-355
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• 2015

Background: The tuberculin skin test (TST) is the standard tool to diagnose latent tuberculosis infection (LTBI) in mass screening. The aim of this study is to find an optimal cut-off point of the TST+ rate within tuberculosis (TB) contacts to predict the active TB development among adolescents in school TB outbreaks. Methods: The Korean National Health Insurance Review and Assessment database was used to identify active TB development in relation to the initial TST (cut-off, 10 mm). The 7,475 contacts in 89 schools were divided into two groups: Incident TB group (43 schools) and no incident TB group (46 schools). LTBI treatment was initiated in 607 of the 1,761 TST+ contacts. The association with active TB progression was examined at different cut-off points of the TST+ rate. Results: The mean duration of follow-up was $3.9{\pm}0.9years$. Thirty-three contacts developed active TB during the 4,504 person-years among the TST+ contacts without LTBI treatment (n=1,154). The average TST+ rate for the incident TB group (n=43) and no incident TB group (n=46) were 31.0% and 15.5%, respectively. The TST+ rate per group was related with TB progression (odds ratio [OR], 1.025; 95% confidence interval [CI], 1.001-1.050; p=0.037). Based on the TST+ rate per group, active TB was best predicted at TST+ ${\geq}$ 16% (OR, 3.11; 95% CI, 1.29-7.51; area under curve, 0.64). Conclusion: Sixteen percent of the TST+ rate per group within the same grade students can be suggested as an optimal cut-off to predict active TB development in middle and high schools TB outbreaks.

• 한국노년학
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• v.37 no.3
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• pp.763-781
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• 2017

This study explores the relationship between indirect contacts of older adults and ageism related behaviors by investigating adults' exposure to portrayals of older people and their images in media. This study also investigates how indirect contacts of older adults influence ageism related behaviors such as avoidance and discrimination against older adults through attitudes and social norms about older adults. Using an online survey collected from 252 adults aged 18-64 years, the authors found that indirect contacts of older adults through media predicted attitude toward older adults as well as social norms. The results also revealed that social norm predicted both avoidance and discrimination behavior against older adults while attitude toward older adults only predicted avoidance behavior. Finally, the findings indicated that attitude toward older adults mediated the relationship between indirect contacts through media and avoidance behavior. However, social norm mediated the relationships between indirect contacts through media and discrimination as well as avoidance behaviors. Implication and limitation of the findings are discussed.

• Korean Journal of Culture and Social Issue
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• v.25 no.4
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• pp.279-303
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• 2019

This study investigated effects of Korean students' contacts with International students on Korean college students' multicultural competencies. This study also examined mediating effects of life satisfaction and realistic conflict perception between contacts with international students and multicultural competencies. For the purpose, 384 Korean college students completed the questionnaires including contacts, life satisfaction, realistic conflicts perception toward international students, everyday multicultural competencies, and demographic information. The results indicate that number of contacts predicts cultural self-efficacy and cultural knowledge, whereas contact diversity predicts cultural openness. Life Satisfaction predicts cultural openness, cultural self-efficacy, and cultural knowledge, and realistic conflicts perception predicts all subscales of everyday multicultural competencies scale other than cultural knowledge. Results also discovered that life satisfaction mediates the relationship between contact diversity and multicultural competencies, but realistic conflict perception did not mediate between contact diversity and multicultural competencies. Based on the results, the suggestions to enhance college students' multicultural competencies were discussed.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.98-101
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• 2005

변환 효율이 $16\%$에 근접하는 다결정 실리콘 태양전지를 위한 열처리 공정에 대한 연구를 수행하였다. 고속 열처리 공정이 가능한 RTP 를 사용하여 다결정 실리콘 태양전지의 효율 향상에 요구되는 PECVD $SiN_x$ 반사방지막을 이용한 결정 결함의 수소화 효과를 극대화하는 동시에 양산 가능한 screen-printed contacts 의 특성 (FF >0.76) 올 최적화함으로써 다결정 실리콘 태양전지의 변환 효율을 $15.9\%$까지 향상시킬 수 있었다.