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Siyuan Yujian in the Joseon Mathematics
홍성사,홍영희,이승온,Hong, Sung Sa,Hong, Young Hee,Lee, Seung On The Korean Society for History of Mathematics 2017 Journal for history of mathematics Vol.30 No.4
As is well known, the most important development in the history of Chinese mathematics is materialized in Song-Yuan era through tianyuanshu up to siyuanshu for constructing equations and zengcheng kaifangfa for solving them. There are only two authors in the period, Li Ye and Zhu Shijie who left works dealing with them. They were almost forgotten until the late 18th century in China but Zhu's Suanxue Qimeng(1299) had been a main reference for the Joseon mathematics. Commentary by Luo Shilin on Zhu's Siyuan Yujian(1303) was brought into Joseon in the mid-19th century which induced a great attention to Joseon mathematicians with a thorough understanding of Zhu's tianyuanshu. We discuss the history that Joseon mathematicians succeeded to obtain the mathematical structures of Siyuan Yujian based on the Zhu's tianyuanshu.
선형회귀분석법을 통한 주조용 A356 합금의 인장특성에 미치는 미세조직적 인자의 영향
홍성진 ( Seong Jin Hong ),김상식 ( Sang Shik Kim ),이재현 ( Je Hyun Lee ),권용남 ( Yong Nam Kwon ),이영선 ( Young Seon Lee ),이정환 ( Jung Hwan Lee ) 대한금속재료학회 ( 구 대한금속학회 ) 2006 대한금속·재료학회지 Vol.44 No.8
The effects of microstructural variables, including DAS (dendrite arm spacing), the size of primary a phase, the size of eutectic Si particle and the thickness of eutectic structure, on tensile behavior of A356 cast aluminum alloy were quantitatively identified using linear regression analysis method. For systematic microstructural control in A356 alloy, directional solidification method was used with different solidification rates of 5, 25, 50 and 100 ㎛/s, respectively. The linear regression analysis suggests that both DAS and the size of primary a phase dominantly affect tensile strength of A356 cast aluminum alloy, while tensile ductility is most strongly dependent on the thickness of eutectic structure. The change in tensile behavior with varying microstructural variables in A356 alloy is discussed based on fracto graphic and micrographic observations.
고랭지 여름 무에서 시들음병 발생 현황과 병원균의 병원학적 특성 연구
홍성기(Sung Kee Hong),고형래(Hyoungrai Ko),최효원(Hyo-Won Choi),이영기(Youngkee Lee),김점순(Jeomsoon Kim) 한국식물병리학회 2020 식물병연구 Vol.26 No.4
Incidence of Fusarium wilt was surveyed in fields of summer radish in Gangwon province in Korea in 2018 and 2019. The disease started in early July and spread rapidly in hot summer of late July and August and in severe case, reached up to 80% in a field in Gangneung area. Symptoms in the seedling stage include poor growth and browning of internal tissue of root. During mid-growth, the leaves of diseased plant turned yellow over time, the surface of the roots changed from white to blackish, and the vascular tissues turned brown. A total of 23 isolates was obtained from the diseased plants and identified as Fusarium oxysporum f. sp. raphani by elongation factor-1a and intergenic spacer sequence analysis. Pathogenicity of the isolates was tested by artificial inoculation to the radish and other plants. All the isolates tested were pathogenic to radish plant, although there were differences in virulence on radish 11 cultivars. However, the isolates were not virulent to other plants except some cruciferous vegetables including Brussels sprouts, rocket, stock, and turnip. The results of pathogenicity test showed that it is necessary to rotate with crops other than cruciferous vegetables in order to prevent Fusarium wilt from radish fields. 2018년과 2019년에 강원도 여름 재배 무 포장에서 시들음병 발생이 조사되었다. 시들음병은 7월 상순 발생했고, 7월 하순과 8월 뜨거운 여름에 급속히 확산되었으며, 심한 경우, 일부 포장에서는 80%까지 발생하였다. 유묘기에 병든 무는 생육이 불량하고 뿌리 내부조직이 갈변되었다. 생육중기 동안시간이 지나면서 병든 잎은 황화되고 뿌리표면은 흰색에서흑색으로 변색되고, 도관조직은 갈변하였다. 병든 식물체로부터 23개 Fusarium균이 분리되었고, EF-1α와 IGS 염기서열 분석에 의해 Fusarium oxysporum f. sp. raphani로 동정되었다. 무와 다른 작물에 대한 인공접종에 의해 병원성이 검정되었다. 11개 품종 간에 차이는 있었으나 모든 균주들은 무에서 병원성이었다. 그러나 로켓, 방울양배추, 스토크, 순무를 포함하는 배추과 작물을 제외하고는 병원성이 없었다. 병원성 검정결과는 무 포장에서 시들음병을 방제하기 위해서는 배추과채소 이외의 작물로 돌려짓기하는 것이 필요하다는 것을 나타낸다.
LPG차량 흡기계통 Cleaning이 엔진 및 배출가스에 미치는 영향
홍성인(Hong, Sung-In),이승철(Lee, Seung-Chul) 한국산학기술학회 2014 한국산학기술학회논문지 Vol.15 No.3
LPG차량의 공기 흡입 시스템에서 먼지 입자의 대부분은 공기 청정기를 통해 제거되지만, 아주 작은 입자는 제거되지 않고 흡기계통에 축적되게 된다. 이 축적된 카본은 공회전 속도 제어와 센서신호 그리고 배출가스에 영향을 주게 된다. 또한 엔진 채터링 현상이나 자동변속기의 변속시점 불량등을 야기시킨다. 이 연구는 세척액을 사용하여 흡기계통을 세척하는 것에 관한 것이다. 워밍업된 챠량에서 흡입호스를 제거하고 세척액을 사용하여 가속시에 세척액 을 흡입장치에 분사시켜 흡기계통을 세척하는 것이다. 세척액을 사용하여 스로틀 바디, ISC, 서지탱크, 흡입매니폴드, 흡기밸브, 연소실까지 세척함으로서 다음과 같은 실험결과를 얻을 수 있다. 스로틀 밸브가 정확하게 작동되어 TPS의 센서 신호 전압이 개선되었으며, 차량이 정지하는 경우 ISC 시스템은 공회전 속도 제어를 원활하게 작동하였다. 또한 일산화탄소는 약 0.15 %, 탄화수소는 약 20~100PPM으로 각각 감소되어 배기가스가 현저하게 개선되었다. At the LPG vehicle air intake system, most of dust particles in the air cleaner are removed. However very small particles are not removed and accumulated. The accumulation of carbon in air intake system is going to affect the idle speed control and sensor signal. It also causes engine chattering and transmission troubles of automatic transmission. This is study about cleaning up intake system using cleaning chemical. We can clean up the intake system by spraying cleaning liquid onto intake device when the engine is idling after intake hose is removed from warmed up vehicle. We can obtain the following experimental results by cleaning up ISC, surge tank, intake manifold, intake valves and combustion chamber. According to this results, the stroll valve works correctly and power rate of engine is up to the standard, it is smoothy to control the idling speed when a vehicle pulls up. After cleaning up CO grow down about 0.15%, HC does about 20~100 ppm.