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Design of consumer center network for warranty services
Minjae Park 한국신뢰성학회 2020 International Journal of Reliability and Applicati Vol.21 No.1
In this paper, a warranty consumer center network is developed to consider different kinds of warranty services for consumers and to match a supply chain network with particular challenges for counter movement management like warranty services such as inspection, examination, recovery, repair and replacement. We present a nonlinear mixed integer programming model (NMIPM) for the structure of the warranty consumer center network for a company. This study develops a design of warranty consumer center of malfunctioned products and inventory locations of products along with the flow of products. We implement different types of recovery processes of products by performing inspection, test, repair, and replacement considering warranty service time limit which results in nonlinearities in the proposed approach. If a malfunctioned product is brought to the warranty consumer center, then a repair service is given first. If its repair time does exceed a repair time limit, instead of continuing to repair, a replacement is given to increase the consumer’s satisfaction. The numerical example is discussed to present the applicability of the methods derived in this paper.
( Minjae Kim ),( Yongsoo Kang ),( Eonseon Jin ) 한국미생물생명공학회(구 한국산업미생물학회) 2019 Journal of microbiology and biotechnology Vol.29 No.9
Zeaxanthin is an important pigment in the photo-protection mechanism of microalgae. However, zeaxanthin epoxidase, an enzyme involved in the accumulation and conversion of zeaxanthin, has not been extensively studied in microalgae. In this work, we report the expression pattern of zeaxanthin epoxidase in Dunaliella tertiolecta (DtZEP) at different light and diverse salinity conditions. To confirm the responsiveness to light conditions, the ZEP expression pattern was investigated in photoperiodic (16 h of light and 8 h of dark) and continuous (24 h of light and 0 h of dark) light conditions. mRNA expression levels in photoperiodic conditions fluctuated along with the light/dark cycle, whereas those in continuous light remained unchanged. In varying salinity conditions, the highest mRNA and protein levels were detected in cells cultured in 1.5 M NaCl, and ZEP expression levels in cells shifted from 0.6 M NaCl to 1.5 M NaCl increased gradually. These results show that mRNA expression of DtZEP responds rapidly to the light/dark cycle or increased salinity, whereas changes in protein synthesis do not occur within a short period. Taken together, we show that DtZEP gene expression responds rapidly to light irradiation and hyperosmotic stress. In addition, ZEP expression patterns in light or salinity conditions are similar to those of higher plants, even though the habitat of D. tertiolecta is different.
( Minjae Park ),( Horim Kim ),( Young Su Lee ),( Hyeri Jo ),( Xin Zhao ),( Jae Young Kim ) 한국폐기물자원순환학회 2022 ISSE 초록집 Vol.2022 No.-
Nitrogen oxides (NO<sub>X</sub>) are air pollutants that cause respiratory and cardiovascular diseases which are mainly produced by the combustion process of power plants, incinerators, and automobiles. Selective catalytic reduction (SCR) and selective non-catalytic reduction (SNCR) are well-known methodologies of reducing nitrogen oxides to nitrogen by ammonia. Anhydrous ammonia (NH<sub>3</sub>, l), ammonia solution (NH<sub>3</sub>, aq), and urea solution (NH<sub>2</sub>CONH<sub>2</sub>, aq) are conventional reductants of SCR and SNCR. Anhydrous ammonia and ammonia solution are highly corrosive resulting high risk of storage and transportation. Compared to the previous two reductants, urea solution is much safer and therefore generally applied to SCR of various systems. To convert urea into ammonia, urea solution requires a pyrolysis process with a temperature of 400℃. Still, the conversion rate of urea solution is low because of by-products produced by complicated reactions. Recently, ammonium carbonate, which decomposes completely into ammonia at 58℃, is being studied as a reductant of SCR and SNCR. However, ammonium carbonate is much more expensive than urea. In this study, to take advantage of both urea and ammonium carbonate, the synergy effect of urea and ammonium carbonate was investigated by comparing the concentration of produced ammonia. Three types of solutions, 4 wt. % urea solution, 2 wt. % ammonium carbonate solution, and a mixture of 4 wt.% urea and 2 wt.% ammonium carbonate solution, were thermally decomposed in a tube furnace. The pyrolysis was performed at a temperature of 200, 300, 350, 400, and 500°C with a residence time of 2 seconds. The produced gas was dissolved into 250 ml of distilled water inside the impinger using air as carrier gas. Ammonia concentration was measured with the Nessler method and UV-Visible Spectrophotometer. This study investigated the synergy effect of urea and ammonium carbonate and how the synergy effect varies depending on the pyrolysis conditions.
Graphene Growth on Metal Wire for Barrier of Filament
Minjae Kim,Young-il Ko,Gilyoung Lee,Bumjin Lee,Keun Soo Kim 한국진공학회 2021 한국진공학회 학술발표회초록집 Vol.2021 No.2
본 연구에서는 동축 금속 필라멘트를 산화로부터 보호하는 보호막으로 그래핀을 사용하기 위한 기초연구이다. CVD 공법을 이용하여 금속와이어 위에 그래핀을 합성하는 조건에 대하여 연구하였다. 와이어의 두께, 금속의 종류에 따른 그래핀의 특성 변화 그리고 금속을 도금한탄소 섬유에서 합성한 그래핀 품질을 확인하였다. 고온에서의 합성 과정 동안 도금된 금속의 증발을 방지하기 위하여 낮은 온도에서 액체소스를 이용한 Rapid CVD Growth를 진행하였다. 실험 조건에 따른 그래핀의 품질 변화를 라만 스펙트럼으로 관측하고 전자현미경을 이용하여 합성된 그래핀의 균일함을 확인하였다.
Minjae Kim,Yeongseon Kim,Sung Hyeon Baeck,Sang Eun Shim 한국탄소학회 2015 Carbon Letters Vol.16 No.1
In this study, in order to improve the thermal and electrical properties of epoxy/graphene nanoplatelets (GNPs), surface modifications of GNPs are conducted using silane coupling agents. Three silane coupling agents, i.e. 2-(3,4-epoxycyclohexyl)-ethyltrimethoxysilane (ETMOS), 3-glycidoxypropyltriethoxysilane (GPTS), and 3-glycidoxypropyltrimethoxysilane (GPTMS), were used. Among theses, GPTMS exhibits the best modification performance for fabricating GNP-incorporated epoxy composites. The effect of the silanization is evaluated using transmission electron microscopy (TEM), scanning electron microscopy, thermogravimetric analysis, and energy dispersive X-ray spectroscopy. The electrical and thermal conductivities are characterized. The epoxy/silanized GNPs exhibits higher thermal and electrical properties than the epoxy/raw GNPs due to the improved dispersion state of the GNPs in the epoxy matrix. The TEM microphotographs and Turbiscan data demonstrate that the silane molecules grafted onto the GNP surface improve the GNP dispersion in the epoxy.
Catherine’s Enlightenment in Northanger Abbey as an English Woman with Subjecthood
Minjae Kim Ewha Institute of English and American Studies 2020 Journal of English and American studies Vol.18 No.1
This paper focuses on reading the world of Jane Austen’s Northanger Abbey as a microcosm of England in the 18th century, and aims to trace how Catherine Morland as a disinhibited subject comes to be enlightened upon realizing that her behavior and mode of judgement that viewed the world blindly in terms of the dichotomy of good and evil pertaining to the imaginary world of the gothic was irrelevant, that “among the English... there was a general though unequal mixture of good and bad”(147). And in the process of coming to be enlightened as such, what Catherine also unwittingly carries out is to serve as the catalyst for Henry Tilney’s personal transformation. I argue that Henry’s change of heart testifies to the change that Catherine as a sincere subject with agency has evoked in the private sphere, the intimate sphere of the Tilney household- or Northanger Abbey that stands in the place of the British empire as the beacon of luxury and improvement. From the perspective that views Catherine not merely as an individual but as an English woman with subjecthood, her revelation is not only that of a personal nature but a social one, an observation of Austen’s that exposes both the ignorance of the previously unreformed Catherine and the vanity of the cosmopolitan General Tilney. Constant throughout the novel is Austen’s brand of irony and satire, rendering which side she takes in the equation ambiguous. Evaluating various characters situated at different points in the spectrum of English national identity and modern improvement, Austen’s work of parody and satire reaches the conclusion that each representation has its limits and vices.