Optimizing opportunistic preventive maintenance strategy for multi-unit system of CNC lathe

Yue Wu,Zhaojun Yang,Jili Wang,Xiaojuan Chen,Wei Hu 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.1

Due to the many components in the multi-unit system (i.e., CNC machine tools), the existing preventive maintenance (PM) strategies conducting independent PM for every component are time-consuming and waste unnecessary maintenance and downtime costs. Hence, this paper introduces the idea of opportunistic maintenance into the PM and proposes an opportunistic imperfect PM approach, which is a more realistic PM policy for a multi-unit system. In this approach, the effect of PM is assumed to be imperfect to correct the failure rate of each unit. According to the corrected failure rate function, the imperfect PM strategy of a single unit is optimized by minimizing the proposed unit maintenance cost rate under the limitation of minimum reliability. Then, these independent imperfect PM strategies for units are rescheduled by the proposed opportunistic PM strategy under the condition of judging the reliability OM threshold of units. We further optimize the opportunistic PM strategy by minimizing the total maintenance cost. Finally, the advantage of our approach is verified by the case study of 18 CNC lathes.

中国学界关于国际发展合作研究的文献计量分析:现状与反思

YUE WU 국민대학교 중국인문사회연구소 2022 중국지식네트워크 Vol.20 No.-

中国愈发重视国际发展合作,提升了其在中国外交中的地位。作为中国外交与对外政策的智力支持,中国学术界关于国际发展合作的研究却较为广泛。目前,既有文献缺少对中国学界关于国际发展合作研究的文献计量统计分析,造成缺乏对中国学界在该领域研究现状的系统性梳理。为此,本文从中国社会科学引文索引(CSSCI)中下载相关文献,利用Citespace软件进行文献计量统计分析,以挖掘中国学界关于国际发展合作研究的特征、演变、热点与前沿,进而解释造成目前研究现状的原因并提出反思与建议。本文认为,中国学界对国际发展合作的研究虽然取得了一定成果,但仍然在概念辨析、科研合作、学科建设、学术期刊建设以及研究议题与议程设置这些方面存在短板,有可以提升的空间。多重因素造成目前的研究短板。这需要中国学界针对上述问题做出回应与努力。

옌쉐퉁의 도덕현실주의 국제관계이론: 포괄적인 검토

YUE WU 계명대학교 국제학연구소 2021 국제학논총 Vol.34 No.-

Established by Professor Yan Xuetong from Tsinghua University, the theory of moral realism in international relations theory represents the achievement of Chinese scholars in innovations in international relations. This theory aims to use political leadership measured by morality as an explanatory variable to analyze the reason and logic of the rising power replacing the dominant position of the dominant power. However, extant literature on the theory fails to systematically review moral realism in Yan’s work, reflecting fragmentation and misunderstanding. Therefore, this study aims to comprehensively review moral realism in international relations, refute and correct problematic understandings, and explore potential applications for theoretical development. It argues that moral realism corresponds to classical realism more than neoclassical realism as a theoretical paradigm and that it is not a theory with ideological purposes serving China’s grand strategy. The study further argues that the theory has not matured owing to issues with concept definition, logical contradictions, and biases of case analysis. Moreover, the influence of ancient Chinese thought in Yan’s moral realism and the limited research object and field may impede its theoretical application. This study proposes applying moral realism to the study of foreign aid and holds that the field of foreign aid conforms to moral realism, alleviates some moral realism deficiencies, and expands the application scope of the theory. 칭화대 옌쉐퉁 교수가 정립한 국제관계론 도덕현실주의는 국제관계 혁신에 대한 중국 학자들의 업적을 대변한다. 이 이론은 도덕이 측정한 정치적 리더십을 설명변수로 삼아 지배적 권력의 지배적 지위를 대신하는 신진 권력의 이유와 논리를 분석하려는 것이다. 그러나, 이 이론에 대한 현존하는 문헌들은 단편화와 오해를 반영하여 옌쉐퉁의 작품에서 도덕 현실주의를 체계적으로 검토하는 데 실패한다. 따라서 본 연구는 국제관계에서 도덕현실주의를 종합적으로 검토하고, 문제가 있는 이해를 반박하고 바로잡으며, 이론적 발전을 위한 잠재적 응용을 탐구하는 것을 목적으로 한다. 도덕현실주의가 이론 패러다임으로서 신고전주의 현실주의보다 고전주의 현실주의에 부합하며, 중국의 대전략에 봉사하는 이념적 목적을 가진 이론이 아니라는 주장이다. 이 연구는 또한 개념 정의, 논리적 모순, 사례 분석의 편향에 대한 문제 때문에 이론이 성숙하지 못했다고 주장한다. 게다가, 옌쉐퉁의 도덕현실주의에 대한 고대 중국 사상의 영향과 제한된 연구 목적과 분야는 그것의 이론적 적용을 방해할 수 있다. 본 연구는 대외원조 연구에 덕현실주의를를 적용하는 것을 제안하며, 대외원조 분야가 덕현실주의에 부합하고, 도덕현실주의의 결핍을 일부 완화하며, 이론의 적용 범위를 확대한다고 주장한다.

Olfactory Emotional Responses of Chinese People to Korean Citrus unshiu Scent - Infused Fabrics Depending on Fragrance Intensity and Color Variables

( Yue Wu ),( Sarmandakh Badmaanyambuu ),( Eunjou Yi ) 한국감성과학회 2017 한국감성과학회 국제학술대회(ICES) Vol.2017 No.-

This study was performed to investigate emotional responses of Chinese people to Korean Citrus unshiu scent -infused cotton fabric and to examine the effect of fragrance intensity and color variables of fabrics on it. A cotton fabric was colored in 2 hues (Yellow, Green) X 3 tones (strong, pale, grayish) combinations for color variables and thereafter it was treated by microcapsules containing Korean Citrus unshiu oil to infuse the scent by rubbing. Thirty two Chinese students at Jeju National University in Korea were invited in the olfactory experience and they were asked to rate the olfactory emotional terms including ‘Strong, ‘Fresh’, ‘Sweet’, ‘Soft’, ‘Comfort’, and ‘Natural’, and the fragrance preference depicted as ‘Like’. As results, fragrance intensity was found to give effect on the intervention of color variables in olfactory emotion of Chinese people. When lower intensity of scent was presented, tone as a color variable was revealed as more dominant on olfactory emotion including ‘Fresh’, ‘Sweet’, ‘Soft’, ‘Comfort’, and ‘Natural’ in that pale-toned fabrics seemed to give rise to higher scores for the emotion terms than the other tones. On the contrary the hue was likely not to affect the olfactory emotion although green is slightly higher in the scores than yellow. Finally olfactory preference was higher for pale and Green and it was the most positively correlated with ‘Fresh’ and ‘Comfort’. These results could be utilized in expecting Chinese consumers’ emotion for Korean Citrus unshiu scent - infused textile products.

Gender Trend in China’s Diplomacy and Foreign Aid: A Moral Realist Perspective

YUE;WU 계명대학교 국제학연구소 2023 국제학논총 Vol.37 No.-

China has engaged in gender issues globally, which demonstrates a gender trend in its diplomacy and foreign aid. However, little existing research has paid attention to this issue or analyzed China’s motivations. Therefore, this paper aims to examine gender trends and explore their characteristics. It also attempts to analyze China’s motivations for global engagement in gender issues and figure out the domestic challenges with the international relations theory of moral realism. It finds that China’s global engagement in gender issues is reflected in its international commitments based on international treaties, support for sustainable development goals, multilateral diplomacy, and foreign aid. However, China shows a contradictory stance on gender issues due to its small aid budget, immature institutionalization, and lack of policy planning. This paper argues that gender issues are the entry point for China to build its humane authority leadership, which is consistent with China’s diplomatic shift to major-country diplomacy of assuming more international responsibilities and engaging in global governance. Nevertheless, gender inequality, negative domestic attitudes toward feminism, and the non-intervention principle constitute internal hurdles to China’s international leadership through leading by example. Hence, it is recommended that China conduct further domestic and international reforms on gender issues to enhance its international leadership.

China’s Cautious Approach to the Venezuelan Crisis: Strategic Overdraft and Nonintervention Principle

YUE;WU 경희대학교(국제캠퍼스) 국제지역연구원 2021 아태연구 Vol.28 No.4

The current China–Venezuela relationship adheres to the South-South cooperation (SSC) model wherein the two countries have established an integrated cooperative approach with “loan-for-oil” deals at its core; however, in contrast with its recent softening stance on interventions, China has taken a cautious approach to the crisis in Venezuela since 2014. Nevertheless, not many studies highlight the reasons for China’s cautiousness. This paper tries to mitigate the gap by examining China’s strategic overdraft as exposed by this response and exploring the challenges in SSC model. It is herein argued that dual overdrafts of material power and credibility constitute the reason for China’s nonintervention in Venezuela. Meanwhile, as the country hoped to continue its presence in Venezuela and is concerned over the overdraft credibility risk by withdrawing, it chose adopt hedging as a form of flexible involvement. To avoid a similar situation in the future, China should neither rely on economic complementarity nor rigidly stick to nonintervention. With national economic and political interests and cooperative sustainability as a guide, China should clarify and redefine its nonintervention principle and adopt preventive measures for risk assessment and cooperation practices to innovate a more sustainable SSC model.

The Forms and Surface Availabilities of Soil Iron and Aluminum Minerals Influence their Adsorptive Stabilization on Litter-Derived Dissolved Organic Carbon

Yue Wu,Jiaguo Jiao,Manqiang Liu,Feng Hu,Huixin Li 한국토양비료학회 2014 한국토양비료학회 학술발표회 초록집 Vol.2014 No.6

An improved resonantly driven piezoelectric gas pump

Yue Wu,Yong Liu,Jian-Fang Liu,Long Wang,Xiaoyang Jiao,Zhigang Yang 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.3

Piezoelectric pumps have the potential to be used in a variety of applications, such as in air circulation and compression. However, piezoelectric membrane pumps do not have enough driving capacity, and the heat induced during the direct contact between the driving part and the gas medium cannot be dissipated smoothly. When the gas is blocked, the piezoelectric vibrator generates heat quickly, which may eventually lead to damage. Resonantly driven piezoelectric stack pumps have high performance but no price advantage. In this situation, a novel, resonantly driven piezoelectric gas pump with annular bimorph as the driver is presented. In the study, the working principle of the novel pump was analyzed, the vibration mechanics model was deter-mined, and the displacement amplified theory was studied. The outcome indicates that the displacement amplification factor is related with the original displacement provided by the piezoelectric bimorph. In addition, the displacement amplification effect is related to the stiffness of the spring lamination, adjustment spring, and piezoelectric vibrator, as well as to the systematic damping factor and the driving frequency. The experimental prototypes of the proposed pump were designed, and the displacement amplification effect and gas output performance were measured. At 70 V of sinusoidal AC driving voltage, the improved pump amplified the piezoelectric vibrator displacement by 4.2 times, the maximum gas output flow rate reached 1685 ml/min, and the temperature of the bimorph remained normal after 2000 hours of operation when the gas medium was blocked.

Effect of microstructures on the shrinkage of injection molding product

Yue Wu,Yao Gong,차경제,박장민 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.3

Shrinkage of injection molding product is a well-known phenomenon which is determined by many factors such as material property, processing condition, mold design, and product design. This study aims to investigate the effect of microscopic structures on the shrinkage of macroscopic product. Flat specimens with and without microstructures were injection molded and the distribution of in-plane shrinkage was measured using an optical method. In the case without microstructures, anisotropic shrinkage is observed and the shrinkage magnitude increases with the distance from the gate. By applying the microstructures, the shrinkage could be reduced significantly, and the effect is especially noticeable when lower packing pressure was applied in the injection molding process. The numerical simulation result is also presented which suggests the importance of material data and lateral motion modeling for accurate prediction of the shrinkage.

Size-dependent dynamic stability of a FG polymer microbeam reinforced by graphene oxides

Yuewu Wang,Ke Xie,Tairan Fu 국제구조공학회 2020 Structural Engineering and Mechanics, An Int'l Jou Vol.73 No.6

The dynamic stability of a functionally graded polymer microbeam reinforced by graphene oxides subjected to a periodic axial force is investigated. The microbeam is assumed to rest on an elastic substrate and is subjected to various immovable boundary restraints. The weight fraction of graphene oxides nanofillers is graded across the beam thickness. The effective Young's modulus of the functionally graded graphene oxides reinforced composite (FG-GORC) was determined using modified Halpin–Tsai model, with the mixture rule used to evaluate the effective Poisson's ratio and the mass density. An improved third order shear deformation theory (TSDT) is used in conjunction with the Chebyshev polynomial-based Ritz method to derive the Mathieu-Hill equations for dynamic stability of the FG-GORC microbeam, in which the scale effect is taken into account based on modified couple stress theory. Then, the Mathieu-Hill equation was solved using Bolotin's method to predict the principle unstable regions of the FG-GORC microbeams. The numerical results show the effects of the small scale, the graphene oxides nanofillers as well as the elastic substrate on the dynamic stability behaviors of the FG-GORC microbeams.