• Electrical & Electronic Materials
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• v.3 no.4
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• pp.332-338
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• 1990

본 연구는 절연유가 금속 파이프 중을 통과할 때 흐르는 유동전류 특성에 대하여 실험적으로 규명하였다. 유동전류는 파이프 길이, 절연유의 속도 및 온도에 따라 변하는 것이 관측되는데 파이프 길이가 4-6cm부근에서 피이크치가 나타나고 유속의 증가에 따라서는 선형적으로 증가하며 그리고 유의 온도가 약 50.deg.C 부근에서 또한 피이크가 나타나고 있다. 절연유에 전하를 주입시키는 수단으로 코로나 방전을 이용하였으며 부코로나 대전된 절연유의 유동전류가 코로나 대전 시키지 않은 절연유나 정코로나 대전된 절연유의 것보다 큰 값이 관측되었다. 이 결과로부터 고체 액체 접촉시 액체중의 음이온이 화학 포텐셜에 의하여 고체 표면에 흡착된다는 사실과 유동전류의 방향 및 발생기구를 해석할 수 있다.

• The Journal of the Korea Contents Association
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• v.22 no.3
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• pp.62-70
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• 2022

This study investigates the temporal structure and movement of floating people near university areas in Daegu metropolitan city, South Korea, before and after Covid-19. In order to determine Daegu's position, the current study compares Daegu and Seoul. The floating population is used as an index to reveal people's various activities in the area known as the local business district, which surrounds the university campus. The information was provided by mobile phone manufacturers. A municipal authority managed a public website where mobile data was made available. Several statistical and visualization techniques were used after the data pre-processing steps. As a result, the floating population fluctuation patterns in both cities in the first half of 2019 and 2020 were comparable. When the Covid-19 diffusion rate in Daegu stabilized in the second half of 2020, the floating population in Daegu increased slightly over the previous year, while the population in Seoul decreased due to the second wave of Covid-19.

• Proceedings of the Korea Information Processing Society Conference
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• 2021.05a
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• pp.301-304
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• 2021

COVID-19 가 장기간 지속됨에 따라 시민들의 생활패턴, 생계 등에 큰 영향을 미치고 있다. 본 논문에서는 서울시의 유동인구 및 카드 소비데이터를 이용하여 COVID-19 가 어떤 영향을 미쳤는지 알아보려 한다. 이를 분석하기 위하여 대용량 데이터인 2019 년 1 월 ~6 월 그리고 2020 년 1 월 ~ 6월 서울시 유동인구 및 카드 소비 데이터를 이용하였다. 서울시를 각 행정구로 나누어 이에 관련한 유동인구의 변화, 유동인구의 증감의 변화를 추정하고 마찬가지로 카드소비데이터의 증감의 변화를 추정하여 서울시 여러 행정구의 유동인구, 카드데이터 두 데이터 간의 연관 관계를 다방면으로 분석하여 엄밀한 인구 밀집도 분석으로 COVID-19 가 서울 지역경제에 미친 영향에 대하여 실증분석을 진행하였다.

• The Journal of the Convergence on Culture Technology
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• v.8 no.6
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• pp.121-126
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• 2022

This study analyzed the survival rate of commercial districts before and after the outbreak of COVID-19 by analyzing Gangnam-gu, Seoul and Suseong-gu, Daegu as independent regions, although the background and distribution of commercial districts are similar. In the basic analysis, the size of the commercial districts was much larger in Gangnam-gu, Seoul, but it was confirmed that the distribution by industry was similar. In both regions, there were more openings than closings before the outbreak of COVID-19 in common, but as the COVID-19 outbreak occurred, the closure ratio of businesses centered on face-to-face services increased significantly. As a result of the survival analysis, it was analyzed that most industries were indifferent to the risk of closure of private institutes before Corona 19, but after the outbreak of Corona 19, it was confirmed that the risk of closure of private institutes increased, especially in Daegu, which was the initial spread of Corona 19. As a result of comparing the survival rate between regions, it was analyzed that the risk of business closure in Gangnam-gu increased relatively after the outbreak of Corona 19, confirming that the contraction in the commercial area of Seoul with a large floating population was greater.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.12
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• pp.3270-3275
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• 1994

Particle trajectory visualization using laser sheet was performed to investigate the corona wind flow interactions in the one-wire and two-wire type electrostatic precipitators. The corona wind generated by corona discharge was not negligible, and strong flow interactions took place owing to the induced circulatory cells. In the case of one-wire type, as the applied voltage was increased and the cross-section mean velocity was decreased, the effect of corona wind became active. In the case of two-wire type, if upstream discharge voltage was relatively higher than downstream discharge voltage, the effect of upstream corona wind was reduced.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.1510-1515
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• 2004

The effects of additive ions on the generation of metallic nanoparticles were evaluated using a corona induced supersonic nozzle. Applying the corona discharge to the nanoparticle generator, a tungsten needle and the supersonic nozzle are used as an anode electrode and a cathode electrode respectively. The corona ions act as nuclei for the silver vapor condensation. The ion density was controlled precisely as varying the applied voltage between electrode and nozzle. The mean diameter of the silver particle decreases as the ion density increases. However, the number concentration of the silver particle tended to increase with the ion density. The size distribution is more uniform as the ion density increases.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.22 no.3
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• pp.125-132
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• 2022

The Ministry of Environment recently analyzed the output data of 10 fine dust measuring stations and, as a result, announced that about 60% had an error that the existing atmospheric measurement concentration was higher. In order to accurately predict fine dust, the wind direction and measurement position must be corrected. In this paper, in order to solve these problems, fuzzy rules are used to solve these problems. In addition, in order to calculate the fine particulate sensation index actually felt by pedestrians on the street, a computer simulation experiment was conducted to calculate the fine particulate sensation index in consideration of weather conditions, temperature conditions, humidity conditions, and wind conditions.

• The Korean Journal of Applied Statistics
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• v.33 no.6
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• pp.697-712
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• 2020

New infectious diseases have broken out repeatedly across the world over the last 20 years; COVID-19 is causing drastic changes and damage to daily lives. Furthermore, as there is no denying that new epidemics will appear in the future, there is a continuous need to develop measures aimed towards responding to economic damage. Against this backdrop, the living population is an important indicator that shows changes in citizens' life patterns. This study analyzes time-based and socio-environmental characteristics by detecting and classifying changes in everyday life caused by COVID-19 from the perspective of the floating population. k-shape Clustering is used to classify living population data of each of the 424 dong's in Seoul measured by the hour; then by applying intervention analysis and One-way ANOVA, each cluster's characteristics and aspects of change in the living population occurring in the aftermath of COVID-19 are scrutinized. In conclusion, this study confirms each cluster's obvious characteristics in changes of population flows before and after the confirmation of coronavirus patients and distinguishes groups that reacted sensitively to the intervention times on the basis of COVID-related incidents from those that did not.

• Journal of the Korean Society of Floral Art and Design
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• no.45
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• pp.31-46
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• 2021

With the advent of the post-COVID19 era, people must maintain social distancing to quarantine. However, this rule deprives people of freedom. Therefore, this study proposes a new normal plan for urban park design using drive-thru to recreate space for people to maintain and enjoy their previous lives while complying with quarantine rules. Olympic Park has a large floating population, and is one of the places where drive-thru is available. Therefore, the study designed this place to be the only cafe that could be operated if other cafes were shut down due to social distancing. The cafes in the park were designed into five spaces based on Olympic Park's flag motifs. The results were as follows. The cafe's name is CUPPY (Cup+Coffee), while each logo letter is expressed using the colors of the Olympic flag: blue, yellow, black, green, and red. The cafe spaces were divided into five continents (Europe, Asia, Africa, Oceania, and America), as symbolized by the Olympic flag, with the driving route shaped like the Olympic logo to match the five spaces. Human beings need change and adaptation in various fields to live in a post-COVID19 era that they have never experienced before. Just as the New Normal changes with time, and should, research is essential for presenting a New Normal in urban park design that reflects this disaster situation following the COVID-19 crisis. On this very point, we expect that this research will serve as a reference for urban park design. Additionally, it is believed that continuous suggestions and research will be necessary to apply the model to more diverse environments.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.2
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• pp.251-259
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• 2000

The ionic wind formed in a nonuniform electric field has been recognized to have a significant effect on particle collection in an electrostatic precipitator(ESP). Under normal operating conditions the effect of ionic wind is not pronounced. However, as the flow velocity becomes smaller, the ionic wind becomes pronounced and induces secondary flow, which has a significant influence on the flow field and the particle collecting efficiency. In this paper, experiments for investigating the effect of secondary flow on collection efficiencies were carried out by changing the flow velocities in 0.2-0.7m/s and the applied voltages in 9-11kV/cm. The particle size distributions and concentrations are measured by DMA and CNC. To analyze the experimental results, numerical analysis of electric filed in ESP was carried out. It shows that particle collection is influenced by two independent dimensionless numbers, $Re_{ehd}\;and\;Re_{flow}$ not by $N_{ehd}$ alone. When $Re_{flow}$, decreases for constant $Re_{ehd}$, the secondary flow prohibits the particle collection. But when $Re_{ehd}$ increases for constant $Re_{flow}$, it enhances the particle collection by driving the particles into the collection region.