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주요 국면에 따른 한·중·일 총요소생산성과 요인 변화 분석
주수현 ( Joo¸ Soohyeon ) 한국경제통상학회 2021 경제연구 Vol.39 No.3
본 연구는 한·중·일의 총요소생산성과 그 요인을 분해하고 변화과정을 중요 시기별로 비교 분석하였다. PWT10.0 통계를 이용하여 50년 균형패널(1969-2019년)을 추출하고 반정규와 절단정규 분포의 기술적 비효율성을 전제로 초월로그형 확률변경생산함수를 추정하였다. 추정결과를 보면, 총요소생산성은 중요 시기별로 한·중·일 간 국면 변화가 나타났다. 한국의 경우, 고도성장 시기 중국과 일본보다 높은 수준을 보여주었으나 외환위기 이후는 중국보다 낮은 수준을 보여준다. 중국은 1978년 개방 이후 급격하게 증가하였으며 1980년대 이후 일본, 1997년 외환위기 이후 한국보다 높은 수준을 보여주었다. 일본은 고도성장 이후 하향 안정세를 보여주고 있으며 2008년 금융위기 이후 증가하는 추세이다. 총요소생산성 증가율을 요인별로 분해를 해 보면 기술진보 효과는 지속적으로 증가하고 있으나 규모경제 효과보다는 그 비중이 낮았다. 기술효율성의 변화는 시간에 따라 모두 증가하였으나 기여도는 낮은 것으로 나타났다. 규모경제 효과는 성장과정에서 높은 기여를 하였지만 고도성장 이후 기여도가 낮아지고 있다. 공통적으로 금융위기 이후 정체되고 있는 총요소생산성 제고가 필요하며 규모경제 효과보다는 기술진보와 기술적 효율성의 기여도를 높여야 하는 과제를 안고 있다. In this study, total factor productivity of Korea, China, and Japan was decomposed and the change process was compared and analyzed by important period. Transcendental logarithmic stochastic frontier production function was estimated using the 50-year balanced panel under the premise of the technical inefficiency of seminormal and truncated normal distributions. According to the estimation results, the growth rate of total factor productivity showed a change in the phases of Korea, China, and Japan for each important period. In the case of Korea, it showed a higher level than that of China and Japan during the period of rapid growth, but showed a lower level than that of China after the financial crisis. China increased rapidly after opening in 1978, and showed a higher level than Japan after the 1980s and Korea after the 1997 Asian financial crisis. Japan has shown a downward stabilization trend after rapid growth and has been increasing since the 2008 financial crisis. The effect of technological progress in Korea, China, and Japan was continuously increasing, but its proportion was lower than the effect of economies of scale. All changes in technological efficiency increased over time, but their contribution was low. The effect of economies of scale made a high contribution to the growth process, but the contribution has decreased after high growth. In common, it is necessary to increase total factor productivity, which has been stagnant since the financial crisis, and it is tasked with increasing the contribution of technological progress and technological efficiency rather than the effect of economies of scale.
Inhibition of Streptococcus mutans biofilm formation on composite resins containing ursolic acid
Soohyeon Kim,Minju Song,Byoung-Duck Roh,Sung-Ho Park,Jeong-Won Park 大韓齒科保存學會 2013 Restorative Dentistry & Endodontics Vol.38 No.2
Objectives: To evaluate the inhibitory effect of ursolic acid (UA)-containing composites on Streptococcus mutans (S. mutans) biofilm. Materials and Methods: Composite resins with five different concentrations (0.04, 0.1, 0.2, 0.5, and 1.0 wt%) of UA (U6753, Sigma Aldrich) were prepared, and their flexural strengths were measured according to ISO 4049. To evaluate the effect of carbohydrate source on biofilm formation, either glucose or sucrose was used as a nutrient source, and to investigate the effect of saliva treatment, the specimen were treated with either unstimulated whole saliva or phosphate-buffered saline (PBS). For biofilm assay, composite disks were transferred to S. mutans suspension and incubated for 24 hr. Afterwards, the specimens were rinsed with PBS and sonicated. The colony forming units (CFU) of the disrupted biofilm cultures were enumerated. For growth inhibition test, the composites were placed on a polystyrene well cluster, and S. mutans suspension was inoculated. The optical density at 600 nm (OD600) was recorded by Infinite F200 pro apparatus (TECAN). One-way ANOVA and two-way ANOVA followed by Bonferroni correction were used for the data analyses. Results: The flexural strength values did not show significant difference at any concentration (p > 0.01). In biofilm assay, the CFU score decreased as the concentration of UA increased. The influence of saliva pretreatment was conflicting. The sucrose groups exhibited higher CFU score than glucose group (p < 0.05). In bacterial growth inhibition test, all experimental groups containing UA resulted in complete inhibition. Conclusions: Within the limitations of the experiments, UA included in the composite showed inhibitory effect on S. mutans biofilm formation and growth.
Diffusion Range and Pool Formation in the Leakage of Liquid Hydrogen Storage Tank Using CFD Tools
( Soohyeon Kim ),( Minkyung Lee ),( Junghwan Kim ),( Jaehun Lee ) 한국공업화학회 2022 공업화학 Vol.33 No.6
In liquid hydrogen storage tanks, tank damage or leakage in the surrounding pipes possess a major risk. Since these tanks store huge amounts of the fluid among all the liquid hydrogen process facilities, there is a high risk of leakage-related accidents. Therefore, in this study, we conducted a risk assessment of liquid hydrogen leakage for a grid-type liquid hydrogen storage tank (lattice-type pressure vessel (LPV): 18 m<sup>3</sup>) that overcame the low space efficiency of the existing pressure vessel shape. Through a commercially developed three-dimensional computational fluid dynamics program, the geometry of the site, where the liquid hydrogen storage tank will be installed, was obtained and simulations of the leakage scenarios for each situation were performed. From the computational flow analysis results, the pool formation behavior in the event of liquid hydrogen leakage was identified, and the resulting damage range was predicted.
SooHyeon Joen,SuHyeon Lee,Sanghun Bae,Eunso Yu,Goo-Rak Kwon 한국차세대컴퓨팅학회 2021 한국차세대컴퓨팅학회 학술대회 Vol.2021 No.05
신종 코로나바이러스 감염증(코로나19)으로 커져버린 배달 시장에 자율주행차가 필요하다. 그럼에도 불구하고 아직 안전을 위한 기술이 부족해 실용화되지 않았다. 본 논문은 좀 더 안전한 주행을 찾아보고 어떤식으로 물건을 안전하게 전달할 건지에 대한 방법을 찾기 위한 연구입니다. 추진 계획으로는 주행을 위한 신호등 표지판 인식과 자동주차 그리고 여러 상황에 대한 긴급정지 및 Database를 연결한 후 학교 근처나 사고가 많이 일어났던 장소에서는 서행을 하도록 하는 성능을 실험한다. 그리고 배달에서 가장 중요한 물품받을 사람을 찾기위한 휴대폰과 연결하여 구매자에게 전달하기 위한 다양한 통신 체계를 구축한다.