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        • KCI등재

          A Post-processing Technique for the Improvement of Color Blurring Using Modulations of Chroma AC Coefficients in DCT-coded Images

          이성학 한국멀티미디어학회 2008 멀티미디어학회논문지 Vol.11 No.12

          In this paper, we propose a post-processing technique developed for the subjective improvement of color resolution in DCT-coded color images. The high frequency components caused by complex object parts are compressed and impaired through DCT-based image processing, so color distortions such as blurs in high saturated regions are observed. It's mainly due to the severe loss of color data as Cb and Cr. Generally, the activities of chroma elements in DCT domain correlate strongly with that of luminance as spatial frequency gets higher, and based on the relations between chroma and luma AC activities, we compensate destructed Cb, Cr coefficients using modifications from Y coefficients. Simulation results show that the proposed method enhances color resolution in high saturated region, and improves the visual quality.

        • KCI등재

          급냉응고 처리된 초내열 합금 A-286 의 기계적 성질 및 강화기구

          이성학,신기삼,Kelly, Thomas F,Flinn, John E 대한금속재료학회(대한금속학회) 1996 대한금속·재료학회지 Vol.34 No.3

          Mechanical test data of superalloy A-286 show that there is a significant increase in tensile strength after rapid solidification processing (RSP). The mechanism of mechanical property improvement upon RSP was studied by TEM quantitative defect analysis and the data analysis using strengthening models. The most prominent microstructural alterations by RSP are found in the precipitates and in the grain growth behavior. On average, the precipitates in RSP samples are smaller, have higher volume fractions, and are much more stable than their conventionally processed counterparts. The increased tensile strength of the RSP samples is found to be the result of the increased volume fraction and number density of second phase particles. However, the strengthening came mostly through grain growth inhibition by the second phase particles, which in turn increased the strength via Hall-Petch relationship. This study shows the importance of recrystallization and thus the method of consolidation for effective strengthening.

        • 韓國古邑의 置廢 및 名號陞降 : 變遷攷

          李聖學 경북대학교 사회과학대학 1984 社會科學 Vol.3 No.-

          1. The old towns (Eub)in korea were devided into Gyeong(京), Bu(府), Ju(州), Gun(郡) and Hyeon(縣). Their characteristics were changed according to the period. The Eub(邑) can be classified to three types: the Large Eub(大邑) was higher than Ju(州), Gun(郡) was Middle Eub(中邑) and Hyeon(縣) was Small Eub(小邑). Generally, Large Eub(大邑) has been developed to city, Gun Eub(郡邑) has been the seat of Gun(郡) offices and Hyeon Eub(縣邑) has been the seat of Eub (邑)or Myeon(面) offices. 2. The change of old towns has an important being on the social characteristics to the geographical ones. In many cases, Eub(邑) which was related with the royal family and meritorious retainer was rasised, but a place noted in connected with a rebellious retainer and criminal was degraded in the status. 3. The change of district name was usually concomitant with the change of place name. Therefore place name of same place was changed according to the period.

        • 韓國歷史地理硏究 : 陸上 交通(主로 驛站制를 中心으로)에 關한 考察 (The system of Yeuk-Cham in the over-land communication)

          李聖學 경북대학교 1968 論文集 Vol.12 No.-

          1. The system of Yeuk-Cham (驛站) is a conveying method of an official document in the system of bureaucratic government and centralization. It is essential function but has transformation. 2. The Yeuk-Cham divides up three types according to the significance. 3. The distribution of Yeuk-Cham means human development and the circumstance, and a number of the large-Yeuks is posted near the Capital and the province of Pyong-An, but the many little-Yeuks is at the southern Korea. 4. The management of Yeuk is different by rank. Its- treatment had different grade by official status. 5. The system of Phal-Cham(撥站) has other function, and it is Ki-Phal(騎撥) (carried by house) from the Capital to I-Chu. For Korea has a deep relation with China, but from Dong-Rae to Ham-Kyung it is Bo-Phal(步撥). 6. The settlements originated by Yeuk-Cham, disregarded by the society at Yi-Dynasty. 7. Yeuk-Cham was abolished by the development of railway and road, but their relation is importance.

        • 地域 硏究의 計量的 方案과 實際 : 主로 土地의 垂直的 利用度 硏究

          李聖學 경북대학교 교육대학원 1970 논문집 Vol.1 No.-

          ⑴ This study suggests quantitative method whch helps to know the limited height of crop-cultivation in land-utilization, and apply it to area. ⑵ The measurement method of crop-culivation in land-utilization. ① Limited Height=(A-B)/R×100 A: Average temperature of the region B: Cultultivation-condition of aptitude temperature of Crop-cultivation R: Lapse rate ⑶ Regression equation of temperature on latitude and its correlation and regional differences, as follow: (See Figure 7 and pp.11∼12) ⑷ The slope of Regression line is small when the Regnession-coefficient is small, and this is same ration of regional differences of temperature, therefore differences of crop-cultivation are smaller in annual crops than perannual crops. ⑸ Regression Equation of Y on X in Korea ◁표 삽입▷ (원문을 참조하세요)

        • 韓國 行政區域의 『縣』에 關한 硏究 : 歷史地理學的 考察 By method of Historical Geography

          李聖學 慶北大學校 1980 論文集 Vol.29 No.-

          1. "Hyun" have been a unit name of administrative district since establishment of "Hansagun" in Korea. "Boo" "Gun" and "Hyun", which were subordinated to "Do", had coordinative relationship each other. But "Hyun" was the lower hierarchy than "Boo""Gun" in the sense of the magistval-ship. 2. There were a lot of changes in the upgrading and downgrading. the establishment and abandenment, and the subordination and coalition of "Hyun". The reason is not due to the change of Geographical characteristics but to the change of Social relationship. 3. Even in the same "Hyun", there were two kinds of magistral-ship. And there was hierachical relation between dominative and subordinative "Hyun". 4. "Hyun" was abolished by the local administrative district reform in 1895 A.D. (King Kojong 32) in Korea. Then the previous "Hyun" area was reorganized to "Gun" or "Myun" area. But "Hyun" is continuing existence in the neighboring country such as Japan and China. By the was, As "Hyun" in Japan cooresponds to "Do" in Korea nowadays, the characteristic of "Hyun" is quite different from that of Korea. 5. "Hyun" as the unit name of administrative district has been abolished. But the name of "Hyun" is used as the name of "Gun" or "Myun".

        • 韓國 古代都邑의 歷史地理性

          李聖學 경북대학교 사회과학연구소 1986 社會科學硏究 Vol.2 No.-

          1. The Korean ancient capital was a place noted in connection with the founding fathers of a country. The transfer of the capital depended on rise and fall of a nation. 2. The Korean ancient capital transfered from north to south, because of invasion from north and territorial expantion. 3. As geographical location, the capital of Silla located southeast in terriotory. It is unfavorable rule over a north region but in favor of depense of Japanese pirates. 4. The name of nation was used to the capital name identically. It trends were applied to many ancient tribes. 5. The forming an transfer of capital were not connection with the theory of divination based on topography.

        • KCI등재

          가속전자빔으로 투사된 탄소강의 미세조직 연구

          이성학,권동일,서동우,구랑모,김방광 대한금속재료학회(대한금속학회) 1994 대한금속·재료학회지 Vol.32 No.8

          The present study is concerned with the microstructural analyses of the surface layer hardened by the irradiation of accelerated electron beam in 0.2% and 0.4%C plain carbon steels. Steel specimens were irradiated using an 1.4 MeV electron accelerator, and the microstructures of the irradiated surface regions were examined. Upon irradiation, the ferrite-pearlite matrix adjacent to the specimen surface was changed to the ferrite-martensite structure, whose interface was composed of fine particles and needle-like lamellae. In order to investigate the martensitic transformation mechanism, the simulation test including thermal cycles of abrupt heating and quenching was carried out. It was found from this test that the temperature of the irradiated surface layer was raised to about 1100℃, which was enough to obtain the surface hardening through the transformation from pearlite to martensite. It is also suggested that the proper accelerated electron beam conditions such as the carbon content and the heat input should be determined to improve microstructures for the surface hardening.

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