연구논문 - Fracture and Fracture Mechanics - : SEM 직접관찰에 의한 8090 Al - Li 합금의 파괴기구 연구

이성학,손기선,김낙준 ( Sung Hak Lee,Kee Sun Sohn,Nack J . Kim ) 대한금속재료학회 ( 구 대한금속학회 ) 1991 재료강도 심포지엄 Vol.- No.-

韓國 特殊行政區域의 時代的 地域特性 : 沿革·位置·分布·規模·性格의 歷史地理性

李聖學 경북대학교 사회과학대학 1985 社會科學 Vol.4 No.-

1. The name of Hyang(鄕), So(所), Pu-gok(部曲), Jang(莊) and Cheo(處) are special districts. It were exist from the Silla(新羅) down to the early Cho-sun(朝鮮). The Pu-gok is still the middle Cho-sun(朝鮮) in exitence. 2. Those districts were connected with convict and a producing center of special products. Therefore disregard with inhabitants and districts. Moreover it has regulation of administration. 3. Those districts were distributed mainly borderland or perforate area. So boundary line was formed without relate topography. 4. Those districts were not fixed. The change and the maintenance were variation according to the time and the locality. 5. Those districts were vary in size. The place-name are scarcely ever till now, because of don't desire look back into the past.

도시하천관리 연계 플랫폼 개발(I)

이성학,심규철,구본현,Lee, Sunghack,Shim, Kyucheoul,Koo, Bonhyun 한국수자원학회 2019 한국수자원학회논문집 Vol.52 No.12

In this study, we developed an integrated urban river data platform that collects, cleans, and provides data for urban river management. The urban river integrated data platform has the function of collecting data provided by various institutions using the Open API service. The collected data is purified through pre-processing and loaded into a database. The collected data can be reviewed and analyzed using a visualization system and provided through the Open API, so that it can be used as individual input data by combining them in the urban river model. In addition, the development system for real-time data was developed to apply real-time data to urban river models. Through this, users will be able to reduce the time and effort required for data collection, pre-processing and input data construction, thereby increasing efficiency and scalability in the development of urban river models and systems.

고속도강 압연롤의 미세조직 연구

이성학,김낙준,이희춘,이창길,손기선 대한금속재료학회(대한금속학회) 1994 대한금속·재료학회지 Vol.32 No.3

The main objective of the present study is to clarify the microstructural factors such as tempered martensite matrix, coarse primary carbides, eutectic structures, and fine secondary carbides, which influence fracture properties of high speed steel (HSS) rolls. Three HSS rolls with different Cr content were manufactured by a centrifugal casting method, and the microstructures of their shell regions were investigated quantitatively. MC type primary carbides, together with eutectic ledeburite structures, were observed in the intercellular regions. The observation of fracture processes indicated that these primary carbides cleaved first to form microcracks at very low stress levels. These microcracks were easily propagated along the intercellular networks, leading to predominantly cleavage mode of fracture on fracture surfaces. To improve microstructures for use in the HSS rolls, therefore, it is suggested that the cell size must be minimized to achieve the homogeneous distribution of primary carbides

朝鮮時代 行政區域制의 歷史地理性 : 時代的 地域特性

李聖學 慶北大學校 1983 論文集 Vol.36 No.-

1) The administrative district system of Josun(朝鮮) established in Taejong(太宗) 13th year (A.D. 1413), which had not been nearly changed in its basic system for about 480 years until the eight province (Do : 道) system was abolished in Gojong(高宗) 32nd year (A.D. 1895). 2) The administrative district system of Josun(朝鮮) was devided into eight provinces (Do:道) besides a independent province, Hanseong-bu(漢城府) including a capital. They had jurisdiction horizantaly over 330 districts such a Bu(府), Dae-Dohobu(大都護府), Mok(牧), Dohobu(都護府), Kun(郡), Hyun(縣) 3) The size(in productive land and population) of districts was generally related to district names, and its relationship was closer in the latter period of Josun(朝鮮) than the former period. 4) The change of district names was partly due to historical change of geography, but mainly due to social change. 5) The special administrative districts of Josun(朝鮮), Bugok(部曲), Hyang(鄕), and So(所) was reorganized to Hyun(縣) or Chon(村) in the latter period of Josun(朝鮮), and so they were almost abolished.

韓國 行政區域의 「郡」에 關한 歷史地理

李聖學 慶北大學校 1982 論文集 Vol.33 No.-

1) At the age of "Han-Sa Gun"(漢四郡), the "Gun"(郡) system had "Hyun"(縣) in its area. But, after the "Sam-Guk6(三國) age, "Gun" and "Hyun" had its own province, ie, it had its originality. 2) The ascent and descent of the name of "Gun"(郡) was mainly due to the reasous of the king's household, a meritorious retainer, a rebellious subject and a criminals, etc. 3) However, Nowodeuys "Gun"(郡) system is based on the reorganization of an administrative district at the age of Japan-empire. At that time, the whole country was divided into 13 provinces and 220 "Gun"s under them.

자동차 클러치용 고강도 스프링 강대의 피로특성

이성학,신장철 대한금속재료학회 1996 대한금속재료학회 학술대회 개요집 Vol.1996 No.1

W 치환 22Cr-5Ni 이상 스테인리스강에서 용접 열영향부의 부식저항성에 관한 연구

이성학,김종민,박화순,안용식 대한금속재료학회 1999 대한금속재료학회 학술대회 개요집 Vol.1999 No.1

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주조 A356 Al-SiCp 복합재료의 파괴인성 해석 연구

이성학,서동우,권동일 대한금속재료학회(대한금속학회) 1996 대한금속·재료학회지 Vol.34 No.1

The present study aims at investigating the effects of microstructure on fracture toughness of A356 aluminum matrix composites reinforced with 15 volume percent SiC particulates. These A356 Al SiC_P composites were processed by conventional permanent mold resting and squeeze casting methods, and notch fracture toughness tests were conducted on these two composites in order to identify critical fracture parameters using a critical strain criterion. The composite microstructure was composed of SiC particulates and eutectic Si particles which were mostly segregated at intercellular boundaries. Tensile properties of the squeeze cast composite were superior to those of the re-past composite because of more homogeneous distribution of SiC and eutectic Si particles and elimination of cast defects. Fracture toughness analyses revealed that the improved fracture toughness of the squeeze cast composite, compared to the re-cast composite, was due to the increase in the reference critical strain while intercellular sizes are similar.

P/M 2009 Al-SiCp 복합재료의 기계적 성질에 미치는 성형온도의 영향

이성학,신기삼,정동섭 대한금속재료학회(대한금속학회) 1996 대한금속·재료학회지 Vol.34 No.1

The present study aims at investigating powder metallurgy (P/M) fabrication processes of high performance 2009 Al composites reinforced with SiC particulates. In particular, the effect of consolidation temperature during the composite processing on microstructure and mechanical properties has been focused on. Rapidly solidified 2009 Al powders produced by commercial atomization technique were mixed with SiC particulates using a fluidized zone mixer. Composite billets were consolidated using a vacuum hot press at the temperature range from 560℃ to 620℃ under the pressure of 50 MPa, and then extruded at 450℃. Using the hot pressing temperature of 560℃, good quality Al-SiCp composite billets having relatively homogeneous microstructure and sound Al/SiC interfacial bonding were obtained, while the composite billets consolidated at the higher temperatures contained SiC depleted regions because of the larger amount of liquid. These SiC depleted regions were not removed during the extrusion process, resulting in the unhomogeneous distribution of SiC particulates. The better mechanical properties of the extruded bars were achieved in the composites fabricated with the lower consolidation temperature since they had the uniform distribution of SiC reinforcements together with full densification. Microstructure and mechanical properties were compared with those of the composites processed by Advanced Composite Materials Corp. or the composites reinforced with SiC whiskers so as to obtain a proper perspective of the Al-SiC composites.