헤밍 공정의 횟수가 헤밍 품질에 미치는 영향에 관한 연구

신나은,최문호,최영덕,최해운,장래성,최계광,김세환,윤재웅,이춘규,Shin, Na-Eun,Choi, Moon-Ho,Choi, Young-Deok,Choi, Hae-Un,Jang, Rae-Seong,Choi, Kye-Kwang,Kim, Sei-Hwan,Yun, Jae-Woong,Lee, Chun-Kyu 한국금형공학회 2016 한국금형공학회지 Vol.10 No.1

In this study, it was investigated by comparing the experimental hemming by the 3 steps and 2 steps in order to stabilize the quality of the hemming process. In the experimental results, the three-step hemming superior to the two-step one and the dimensional stability of part that was made by the three-step on was high. When the second stage Hemming has been found that the deflection caused by the force to the wear of the punch becomes larger plane can be folded by the hemming crimping and crimp uncertain.

Renovation of Seoul Radio Astronomy Observatory and Its First Millimeter VLBI Observations

신나은,박용선,변도영,서진국,김동국,민철홍,강현우,Keiichi Asada,Wen-Ping Lo,Sascha Trippe 한국천문학회 2022 Journal of The Korean Astronomical Society Vol.55 No.6

The Seoul Radio Astronomy Observatory (SRAO) operates a 6.1-meter radio telescope on the Gwanak campus of Seoul National University. We present the efforts to reform SRAO to a Very Long Baseline Interferometry (VLBI) station, motivated by recent achievements by millimeter interferometer networks such as Event Horizon Telescope, East Asia VLBI Network, and Korean VLBI Network (KVN). For this goal, we installed a receiver that had been used in the Combined Array for Research in Millimeter-wave Astronomy and a digital backend, including an H-maser clock. The existing hardware and software were also revised, which had been dedicated only to single-dish operations. After several years of preparations and test observations in 1 and 3-millimeter bands, a fringe was successfully detected toward 3C 84 in 86 GHz in June 2022 for a baseline between SRAO and KVN Ulsan station separated by 300 km. Thanks to the dual frequency operation of the receiver, the VLBI observations will soon be extended to the 1 mm band and verify the frequency phase referencing technique between 1 and 3-millimeter bands.

키워드 네트워크 분석을 활용한 유아 또래유능성 관련 연구 분석

이승하(Lee, Seung-Ha),신나은(Shin, Na-Eun) 한국영유아교원교육학회 2021 유아교육학논집 Vol.25 No.3

본 연구의 목적은 키워드 네트워크 분석을 통해 유아 또래유능성 관련 연구동향을 파악하고자 함이다. 이를 위해 국내에서 1998년부터 2020년까지 발간된 총 175편의 유아 또래유능성 관련 KCI 등재 학술지 논문과 그 키워드 220개를 분석대상으로 선정하였다. 선정된 키워드는 Microsoft Excel 2016과 NetMiner 4.0을 사용하여 키워드 네트워크 분석을 적용하였다. 연구결과는 다음과 같다. 첫째, 유아 또래유능성 관련 연구는 1998년을 시작으로 초반 10년간은 발간이 저조했으나, 2000년대 후반을 기점으로 그 수가 폭발적으로 증가하였다. 둘째, 출현빈도 상위 31개의 키워드 전반은 유아 개인적인 변인과 관련이 있었으며, 출현 빈도가 가장 높은 키워드는 ‘기질’이었다. 셋째, 키워드 네트워크의 기본 속성을 분석한 결과 노드 수는 220개, 링크 수는 431개, 밀도는 0.018, 포괄성은 0.995, 평균연결정도는 3.918, 직경은 8, 평균 연결거리는 3.49, 군집화계수는 0.737로 나타났으며, 멱함수 분포가 나타났다. 마지막으로, 키워드 네트워크의 중심성을 분석한 결과 연결중심성과 근접중심성이 가장 높은 키워드는 ‘교사-유아관계’, 매개중심성이 가장 높은 키워드는 ‘자아존중감’이었다. 또한, 연구물 간에 중심이 되는 키워드와 그렇지 못한 키워드도 나타났다. 본 연구는 유아 또래유능성에 영향을 주고받는 다양한 변인을 파악함으로써 유아의 또래관계 증진 및 사회교육 프로그램 개발에 풍부한 정보를 제공하였다는 의의가 있다. This study aimed to identify research trends in preschoolers’ peer competence using keyword network analysis. A total of 175 KCI-listed articles conducted from 1998 to 2020 in South Korea were selected, and 220 keywords were extracted from them. The 220 keywords were analyzed using Microsoft Excel 2016 and NetMiner 4.0. The results are as follows. First, there was a very limited research on preschoolers’ peer competence from 1998 to 2007, but the number of studies exploded in the late 2000s. Second, the top 31 most frequently appeared keywords of preschoolers’ peer competence studies were more likely to be related to preschoolers’ personal variables than their parents’ or family variables. Especially “temperament” showed the highest frequency among the 31 keywords. Third, analysis of the underlying properties of the keyword network showed 220 nodes, 431 links, density 0.018, inclusiveness 0.995, average degree 3.918, diameter 8, mean distance 3.49 and clustering coefficient 0.737, with power-law distribution. Finally, the keyword with the highest degree centrality and closeness centrality was “teacher-preschooler relationship” and the keyword with the highest betweenness centrality was “self-esteem.” Further analysis discussed the relationships among researchers’ interests and relatively ignored topics in preschoolers’ peer competence research. This study provides abundant information for the promotion of peer relationships and useful information for the development of social education programs for preschoolers by identifying various variables that affect their competence.

해외 천문학 교육 프로그램 개발: 캄보디아

김상철,여아란,박창범,이정애,이강환,신용철,신나은,신지혜,최윤호,권순길,김태우,윤호섭,박순창,성언창,박수종 한국천문학회 2019 天文學論叢 Vol.34 No.2

The Korean Astronomical Society (KAS) Education & Public Outreach Committee has provided education services for children and school teachers in Cambodia over the past three years from 2016 to 2018. In the first year, 2016, one KAS member visited Pusat to teach astronomy to about 50 children, and in the following two years of 2017 and 2018, three and six KAS members, respectively, executed education workshops for ∼ 20 (per each year) local school teachers in Sisophon. It turned out that it is desirable to include both teaching of astronomical knowledge and making experiments and observations in the education in order for the program to be more effective. Language barrier was the main obstacle in conveying concepts and knowledge, and having a good interpreter was very important. It happens that some languages, such as the Khmer of Cambodia, do not have astronomical terminologies, so that lecturers and even the education participants together are needed to communicate and create appropriate words. Handout hardcopies of the education materials (presentation files, lecture/experiment summaries, terminologies, etc.) are extremely helpful for the participants. Actual performing of assembling and using astronomical telescopes for night sky observations has been lifetime experience for some of the participants, which might promote zeal for knowledge and education. It is hoped that these education services for developing countries like Cambodia can be regularly continued in the future, and further extended to other countries such as Laos and Myanmar.

Using the Crab Nebula as Polarization Angle Calibrator for the Korean VLBI Network

감민철,Sascha Trippe,변도영,박종호,강신철,신나은,이상성,정태현 한국천문학회 2023 Journal of The Korean Astronomical Society Vol.56 No.1

The Crab nebula is widely used as a polarization angle calibrator for single-dish radio observations because of its brightness, high degree of linear polarization, and well-known polarization angle over a wide frequency range. However, the Crab nebula cannot be directly used as a polarization angle calibrator for single-dish observations with the Korean VLBI Network (KVN), because the beam size of the telescopes is smaller than the size of the nebula. To determine the polarization angle of the Crab nebula as seen by KVN, we use 3C 286, a compact polarized extragalactic radio source whose polarization angle is well-known, as a reference target. We observed both the Crab nebula and 3C 286 with the KVN from 2017 to 2021 and find that the polarization angles at the total intensity peak of the Crab nebula (equatorial coordinates (J2000) R.A. = 05ㄹh34m32.3804s and Dec = 22º00’44.0982”) are 154.2º ± 0.3º, 151.0º ± 0.2º, 150.0º ± 1.0º, and 151.3º ± 1.1º at 22, 43, 86, and 94 GHz, respectively. We also find that the polarization angles at the pulsar position (RA = 05h34m31.971s and Dec = 22º00’52.06”) are 154.4º ± 0.4º, 150.7º ± 0.4º, and 149.0º ± 1.0º for the KVN at 22, 43, and 86 GHz. At 129 GHz, we suggest to use the values 149.0º ± 1.6º at the total intensity peak and 150.2º ± 2.0º at the pulsar position obtained with the Institute for Radio Astronomy in the Millimeter Range (IRAM) 30-meter Telescope. Based on our study, both positions within the Crab nebula can be used as polarization angle calibrators for the KVN single-dish observations.