The surface of carbon films deposited with inverted plasma fireballs is analysed in this paper. Measurements were conducted with Raman spectroscopy, atomic force microscopy and nanoindentation. The latter was used to obtain Young’s modulus as well as Martens and Vickers hardness. The roughness of the film was measured by atomic force microscopy and its thickness was measured. It was shown with Raman spectroscopy that the films are homogeneous in terms of atomic composition and layer thickness over an area of about 125 × 125 mm. Furthermore, it was demonstrated that inverted plasma fireballs are a viable tool for obtaining homogeneous, large area carbon films with rapid growth and very little energy consumption. The obtained films show very low roughness.

2020년 9월 23일 새벽 1시 39분경 전국 여러 곳에서 목격된 서천 화구는 대기권에 진입 후 두 차례 폭발했음 이 전천 카메라 영상에 확인되었으며, 충격파는 한반도 서남부 지역 지진 및 인프라사운드 관측소에 기록되었다. 17개 관측소에서 측정된 화구 지진파 및 음파의 도달 시간 정보와 베이지안에 기초한 격자탐색법으로 화구 발생 위치를 추정하였다. 위치결정에는 대기권 바람 분포에 따른 음파 속도 변화를 반영하여 계산 결과의 신뢰도를 높였다. 화구 발생 위치는 36.050°N, 126.855°E, 고도 35 km로 전천 카메라 영상에서 관측된 두번째 화구 위치와 유사하였다. 서해 상공에서 한반도 내륙으로 입사하며 발생한 두 차례의 폭발이 근거리 인프라사운드 관측소에서 확인되었다. 또한 서천 화구 폭발 충격음은 장거리를 전파하여 최대 ~266 km에 위치하는 관측소에서도 기록되었으며 파형 모델링이 관측 결과를 뒷받침하였다. 인프라사운드 5개 관측소에서 측정된 두번째 화구 폭발 신호의 평균 주기는 ~0.4 s이며, 주기-폭발 에너 지 관계식을 적용했을 때 서천 화구의 폭발 에너지는 약 0.3 ton TNT 폭발에 상응한다.

We give a detailed description of the installation and operation of a double-station meteor detection system which formed part of a research & education project between Korea Astronomy Space Science Institute (KASI) and Daejeon Science Highschool. A similar system is currently not existing in South Korea. A total of six light-sensitive CCD cameras were installed with three cameras at SOAO and three cameras at BOAO observatory. A double-station observation of a meteor event enables the determination of the three-dimensional heliocentric orbit in space. This project was initiated in response to the Jinju reball event in March 2014. The cameras were installed in October/November 2014. The two stations are identical in hardware as well as software. Each station employes sensitive \Watec-902H2" cameras in combination with relatively fast f/1.2 lenses. Various elds of views were used for measuring dierences in detection rates of meteor events. We employed the SonotaCo UFO software suite for meteor detection and their subsequent analysis. The system setup as well as installation/operation experience is described and rst results are presented. We also give a brief overview of historic as well as recent meteor (fall) detections in South Korea. For more information please consult http://meteor.kasi.re.kr.

The summer polar lower thermosphere (90–100 km) has an interesting connection to meteors, adjacent to the mesopause region attaining the lowest temperature in summer. Meteors supply condensation nuclei for charged ice particles causing polar mesospheric summer echoes (PMSE). We report the observation of meteor trail with nearly horizontal transit at high speed (20–50 km/s), and at last with re-enhanced echo power followed by diffusive echoes. Changes in phase difference between radar receivers aligned in meridional and zonal directions are used to determine variations in horizontal displacements and speeds with respect to time by taking advantage of radar interferometric analysis. The actual transit of echo target is observed along the straight pathway vertically and horizontally extended as much as a distance of at least 24 km and at most 29 km. The meteor trail initially has a signature similar to ‘head echoes’, with travel speeds from 20 – 50 km/s. It subsequently transforms into a different type of echo target including specular echo and then finally the power reenhanced. The reenhancement of echo power is followed by fume-like diffusive echoes, indicating sudden release of plasma as like explosive process probably involved. We discuss a possible role of meteor-triggered secondary plasma trail, such as fireball embedded with electrical discharge that continuously varies the power and transit speed.