• Title/Summary/Keyword: round trip time

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A Study of the Characteristics of Highly Spatially Resolved CW-laser-based Aerosol Lidar (고공간분해능 연속 광원을 이용한 미세먼지 라이다의 신호 특성에 관한 연구)

  • Sim, Juhyeon;Kim, Taekeong;Ju, Sohee;Noh, Youngmin;Kim, Dukhyeon
    • Korean Journal of Optics and Photonics
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    • v.33 no.1
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    • pp.1-10
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    • 2022
  • In this study we introduce a new method for high-spatial-resolution continuous wave (CW) aerosol lidar that has a high spatial resolution in the near field and a low spatial resolution at long distances. A normal lidar system uses a nanosecond-pulse laser and measures the round-trip TOF between the aerosol and laser to obtain range resolution. In this study, however, we propose a new type of spatially resolving aerosol lidar that uses laser-scattering images. Using a laser-light-scattering image, we have calculated the distance of each scattering aerosol image for a given pixel, and recovered the short-range aerosol extinction. For this purpose, we have calculated the distance image and the contribution range of the aerosol to the given one-pixel image, and finally we have calculated the extinction coefficients of the aerosol with range-resolved information. In the case of traditional aerosol lidar, we can only obtain the aerosol extinction coefficients above 400 m. Using our suggested method, it was possible to extend the range of the extinction coefficient lower then several tens of meters. Finally, we can remove the unknown short-range region of pulsed aerosol lidar using our method.

Changes in Public Bicycle Usage Patterns before and after COVID-19 in Seoul (코로나19 전후 서울시 공공 자전거 이용 패턴의 변화)

  • Il-Jung Seo;Jaehee Cho
    • The Journal of Bigdata
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    • v.6 no.2
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    • pp.139-149
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    • 2021
  • Ddareungi, a public bicycle service in Seoul, establishes itself as a means of daily transportation for citizens in Seoul. We speculated that the pattern of using Ddareungi may have changed since COVID-19. This study explores changes in using Ddareungi after COVID-19 with descriptive statistical analysis and network analysis. The analysis results are summarized as follows. The average traveling distance and average traveling speed have decreased over the entire time in a day since COVID-19. The round trip rate has increased at dawn and morning and has decreased in the evening and night. The average weighted degree and average clustering coefficient have decreased, and the modularity has increased. The clusters, located north of the Han River in Seoul, had a similar geographic distribution before and after COVID-19. However, the clusters, located south of the Han River, had different geographic distributions after COVID-19. Traveling routes added to the top 5 traffic rankings after COVID-19 had an average traveling distance of fewer than 1,000 meters. We expect that the results of this study will help improve the public bicycle service in Seoul.

A study on the figurative art expression reflected on the relationship with the animal companion and the inner self - Focusing on works by Lee Heeyeong -

  • Lee, Hee-Young;Cho, Myung-Shik
    • Cartoon and Animation Studies
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    • s.42
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    • pp.293-313
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    • 2016
  • The target stimulating human's sensitivity can include several things; the first is human like us including beautiful women and cute babies. The next ranking is the dog animal that established itself as a human's companion. It is the 3B law(beauty, baby, beast - much used in the ad or election due to the positive image) that is widely used in the advertising. This relationship is being expressed in the art history for a long time. Dogs that have lived a history more than 10 thousand years with humans hunted, protected flock of sheep, and kept the farmer's house and property. They have been human's assistants and companion who entered into the modern urban culture. Like this, dogs have adapted to several situations endlessly such as the nomadic life, farming, country life, and urban life. This paper will explore the close relationship of humans and companion animals through various icons of dogs and pups that appeared through a number of artists' skills. The companion animal means an animal that lives with people, which means the relationship of round-trip rather than the one-way relation those each other gives a help. Therefore, there artist tries to examine the figure of great hunter for survival, highly evaluated figure as the royal dignity, and the mascot-like figure delivering the daily happiness to modern people as presenting joy through a discussion of the 'countenance', a visual signal of the dogs and pups. They have been influenced by screen and popular media in 20C. Snoopy, a main character of and the movie <101 Dalmatians> made a success on the theater and television when Beagle and Dalmatian were prevalent. These main characters make audience feel happy involuntarily. Like this, the continuous and old friendship of the human and dogs will be confirmed again through the icon of dogs and pups consisting of the communication of artists and readers in the modern shape art, and it is hoped to be a psychological stabilizing effect to modern people living in the intense modern society. Therefore, it is expected this study paper will be reborn as a new text and be expanded as an effective communication in the journey of dogs and human in the future in investigating the communion of dogs and human.