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코로나19 전후 항만 효율성 분석에 관한 연구-체선을 중심으로-
송현근,박홍규 한국통상정보학회 2023 통상정보연구 Vol.25 No.3
Since COVID-19, congestion has become an important factor that can hinder the efficient operation of ports and cause direct and indirect economic damages. Therefore, this study conducted an SBM-DEA analysis with congestion as a undesirable output variable to investigate the impact of congestion on the efficiency of four Korean ports (Busan, Yeosu-Gwangyang, Ulsan, and Incheon) before and after COVID-19. The analysis revealed that the overall efficiency of the ports was lower after the outbreak of COVID-19 than before, and that the efficiency of each port was relatively different depending on its infrastructure and budget. This analysis shows that port efficiency is being negatively affected by congestion both pre- and post- COVID-19. Additionally, port infrastructure and budgets have a direct impact on congestion levels. To enhance port efficiency, it's important to implement appropriate systems and policies to manage congestion while considering the unique characteristics of each port.
송현근,허인도,박현진,남주형,박가빈,공경혜,황영미,김영석,조대호,이왕재,허대영 대한면역학회 2009 Immune Network Vol.9 No.6
Background: Melanoma is the most fatal form of skin cancer due to its rapid metastasis. Recently, several studies reported that selenium can induce apoptosis in melanoma cells. However, the precise mechanism remains to be elucidated. In this study, we investigated the effect of selenium on cell proliferation in murine melanoma and on tumor growth and metastasis in C57BL/6 mice. Methods: Cell proliferation was measured by MTT assay in selenium-treated melanoma cells. Cell cycle distribution was analysized by staining DNA with propidum iodide (PI). mRNA and protein expression related to cell cycle arrest was measured by reverse transcription PCR and western blot. Tumor growth and metastasis was measured by in vivo model. Results: Selenium was suppressed the proliferation of melanoma cells in a dose dependent manner. The growth inhibition of melanoma by selenium was associated with an arrest of cell cycle distribution at G0/G1 stage. The mRNA and protein level of CDK2/ CDK4 was suppressed by treatment with selenium in a time-dependent manner. In vivo, tumor growth was not suppressed by selenium; however tumor metastasis was suppressed by selenium in mouse model. Conclusion: These results suggest that selenium might be a potent agent to inhibit proliferative activity of melanoma cells.
송현근(Song Hyun-Geun),정효원(Jung Hyo-Won),김지환(Kim Ji-Hwan),양일승(Yang Il-Seung),김순철(Kim Soon-Chul),문연준(Moon Youn-Joon) 대한건축학회 2009 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.29 No.1(구조계)
The full penetration welded joint should not be gap, but the welding defects in the field are sometimes occurred. Because the strength reduction in the full penetration welded joint with gaps are expected, the allowable tolerance must be kept. This study, tensile tests on beam-beam welded joints with gaps are conducted to evaluate the relationship between tensile strength and the amount of gaps. The thickness(t) tensile specimens is 19㎜ and, SS400 class steel is used. The main variables are beveling shape(L-type, K type), unevenness(e: 0, 2, 4, 6 (㎜)), backing piece(1, 2), and the unevenness direction (up, down). And, the CO₂ gas shield arc semi-automatic welding is used. Also, the temperature of the welding between pass was less than 250 ℃. Also, comparison of a criterion and to the experiment results was performed. It is concluded that specimens with unevenness over 4㎜ on full penetration welded joint has lower yield strength, maximum strength and smaller deformation ability than a specimen with normal specimen. Afterward, studies of repairing of welded joints are required.