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Chunting Hu,Chen Li,Qiaoya Ma,Ruili Wang,Ya He,Hui Wang,Guo-gang Luo 연세대학교의과대학 2021 Yonsei medical journal Vol.62 No.4
Purpose: Ischemic brain injury results in high mortality and serious neurologic morbidity. Here, we explored the role of SNHG15in modulating neuronal damage and microglial inflammation after ischemia stroke. Materials and Methods: The hypoxia/ischemia models were induced by middle cerebral artery occlusion in mice and oxygenglucosedeprivation/reoxygenation (OGD/R) in vitro. Quantitative real-time PCR (qRT-PCR) and Western blot were conducted todetermine the levels of SNHG15, miR-302a-3p, and STAT1/NF-κB. Moreover, gain- or loss-of functional assays of SNHG15 and miR-302a-3p were conducted. MTT assay was used to evaluate the viability of HT22 cells, and the apoptotic level was determined byflow cytometry. Furthermore, enzyme-linked immunosorbent assay was performed to detect oxidative stress and inflammatorymediators in the ischemia cortex and OGD/R-treated BV2 microglia. Results: The SNHG15 and STAT1/NF-κB pathways were both distinctly up-regulated, while miR-302a-3p was notably down-regulatedin the ischemia cortex. Additionally, overexpressing SNHG15 dramatically enhanced OGD/R-mediated neuronal apoptosisas well as the expression of oxidative stress and inflammation factors from microglia. In contrast, knocking down SNHG15 or overexpressingmiR-302a-3p relieved OGD/R-mediated neuronal apoptosis and microglial activation. Moreover, the rescue experimenttestified that overexpressing miR-302a-3p also attenuated SNHG15 up-regulation-induced effects. In terms of the mechanisms,SNHG15 sponged miR-302a-3p and activated STAT1/NF-κB as a competitive endogenous RNA, while miR-302a-3p targetedSTAT1 and negatively regulated the STAT1/NF-κB pathway. Conclusion: SNHG15 was up-regulated in the hypoxia/ischemia mouse or cell model. The inhibition of SNHG15 ameliorates ischemia/hypoxia-induced neuronal damage and microglial inflammation by regulating the miR-302a-3p/STAT1/NF-κB pathway.
굴곡된 탄소나노튜브로 보강된 적층 복합재 판구조의 고유진동 특성
출템수렌천트 ( Chunt Chultemsuren ),최형배 ( Hyung Bae Choi ),이상열 ( Sang-youl Lee ) 한국복합재료학회 2021 Composites research Vol.34 No.2
본 논문은 Mori-Tanaka법, 혼합법칙 및 Halpin-Tsai 이론식을 적용하여 굴곡진 탄소나노튜브(CNT)로 보강된 복합재의 멀티스케일 고유진동 특성을 규명하였다. Eshelby 텐서를 이용하여 곡률을 갖는 CNT가 함유된 폴리머의 하중 전달 특성값이론을 유도하였다. 도출된 수치해석 결과는 기존의 연구결과와 잘 일치하였다. 본 연구에서 제시한 새로운 결과는 적층 복합재의 CNT 함유량, 굴곡성 및 적층배열의 상호작용 특성을 규명하였다. 주요 결과에 대하여 분석하였으며, CNT 보강 복합재의 실용적 설계를 위한 중요 고려사항을 제시하였다. This paper dealt with multi-scale natural frequency characteristics of wavy CNT (carbon nanotube) reinforced composites by applying the Mori-Tanaka method, rule of mixture, and Halpin-Tsai equation. By compelling benefit of an ad-hoc Eshelby tensor, the load-transfer characteristics of CNT with a waviness implanted in the polymer matrix was determined. The numerical results obtained are in good agreement with those reported by other investigators. Furthermore, the new results reported in this paper show the interactions between CNT weight, waviness ratios and layup sequences of laminated composites. Key observation points are discussed and significant considerations are given in practical designing of CNT reinforced composites.
Collaboration Strategies of Fashion Companies and Customer Attitudes
Eunha Chunt,Linda S. Niehm 한국마케팅과학회 2010 마케팅과학연구 Vol.20 No.1
Collaboration strategies entail infonnation sharing and other varied fonns of cooperation that are mutually beneficial to the company and stakeholder groups. This study addresses the specific types of collaboration used in the fashion industry while also examining strategies that have been most successful for fashion companies and perceived benefits of collaboration fi'om the customer perspective. In the present study we define fashion companies and brands as collaborators and their pmtners or stakeholders as collaboratees. We define collaboration as a cooperative relationship where more than two companies, brands or individuals provide customers with beneficial outcomes utilizing their own competitive advantages on an equal basis. Collaboration strategies entail infOlmation sharing and other varied fonns of cooperation that are mutually beneficial to the company and stakeholder groups. Through collaboration, fashion companies have pursued both tangible differentiation, such as design and technology applications, and intangible differentiation such as emotional and psychological benefits to customers. As a result, collaboration within the fashion industry has become an important, value creating concept. This qualitative study utilized case studies and in-depth interview methodologies to examine customers' attitudes concerning collaboration in the fashion industry. A total of 173 collaboration cases were identified in Korean and international markets from 1998 through December 2008, focusing on fashion companies. Cases were collected from documented data including websites and induSl1y data bases and top ranked pOltal search sites such as: Rankey.com; Navel', Dawn, and ate; and representative fashion infonnation websites Samsungdesignnet and Firstviewkorea. Cases were collected between ovember 2008 and FeblUmy 2009. Cases were selected for the analysis where one or more pmtners were associated with the production of fashion products (excluding textile production), retail fashion products, or designer services. Additional collaboration case information was obtained from news mticles, periodicals, intemet portal sites and fashion inforn1ation sites as conducted in prior studies (Jeong and Kim 2008; Park and Park 2004; Yoon 2005). In total, 173 cases were selected for analysis that clearly exhibited the benefits and outcomes of collaboration efforts and strategies between fashion companies and stakeholders. Findings show that the overall results show that for both partners (collaborator and collaboratee) participating III collaboration, that the major benefits are reduction of costs and risks by sharing resource such as design power, image, costs, technology and targets, and creation of synergy. Regarding types of collaboration outcomes, product/design was most important (55%), followed by promotion (21 %), price (20%), and place (4%). This result shows that collaboration plays an important role in giving life to products and designs, particularly in the fashion industry which seeks for creative and newness. To be successful in collaboration efforts, results of the depth interviews in this study confinn that fashion companies should have a clear objective on why they are doing the collaboration. After setting the objective, they should select collaboratees that match their brand image and target market, make quality co-products that have definite concepts and differentiating factors, and also pay attention to increasing brand awareness. Based on depth interviews with customers customer benefits were categOlized into six factors: pursuit fo; individual character; pursuit for brand; pursuit for scarcity; pursuit for fashion; pursuit for economic efficiency; and pursuit for sociality. Customers also placed more impOItance on imao-e 0' reputation, and trust of brands regarding the cases shown in the interviews.
Lim, Hansang,Mi, Chunting Chris,Su, Wencong IEEE 2017 IEEE Transactions on Vehicular Technology VT Vol.66 No.8
<P>This paper proposes a distance-based two-stage ecological (eco-) driving scheme by using estimation of distribution algorithms (EDA) and model-based prediction of traffic conditions. Before departure, the optimal speed profile for an entire route is generated by an EDA in combination with speedup approaches for a faster computing time, which can optimize the complex cost function of ecodriving without simplification within a reasonably short computing time. This optimization is performed in a distance domain for localizing changes in the optimal speed profile due to traffic conditions while driving. After departure, by taking the optimal speed profile and actual traffic conditions into consideration, the speed profile for a short term-to only the next location-is adapted. In order to reliably react to actual traffic conditions, additional points are interpolated into the long-term distance step and fine control of speeds at the additional points is established, which is based on a predictive model for estimating the spacing to the preceding vehicle. The proposed ecodriving system is evaluated in two types of route conditions, and its results are compared with the optimization result by the quadratic programming method. This comparison shows that an EDA can generate a speed profile with better optimization results in terms of fuel efficiency and driving time within a shorter computing time.</P>
Xinghai Zhang,Qingdi Gong,Jiaqi Li,Chunting Liu,Jingyuan Li 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.9
The effect of cold deformation and annealing temperature on the microstructure evolution and mechanical properties isshown in this research together with a unique short strategy for manufacturing lean duplex stainless steel bars. Furthermore,the effects of post-weld heat treatment (PWHT) and cooling treatments on the microstructure and mechanical properties ofLDX 2101 bars are being investigated. The results demonstrate that the austenite produces a large number of deformationtwins and strain-induced martensite (SIM) as cold deformation increases, and the SIM and austenite follow the traditionalK–S and N–W orientation relationships. The best mechanical properties overall are achieved in LDX 2101 bars that havebeen annealed at 1020 °C. Moreover, short-time PWHT improves the austenite proportion in the heat-affected zone andweld metal, and PWHT can greatly enhance the overall mechanical properties of the welded joints. Additionally, the optimalheat treatment temperature of the welded joints is 1050–1080 ℃. Furthermore, compared to those treated with air cooling,the mechanical properties of the welded joints treated with water quenching following flash butt welding are superior. As aresult, it is recommended that following flash butt welding, the welded joints are given a water-quenching treatment.
Influences of Pump Spot Radius and Depth of Focus on the Thermal Effect of Tm:YAP Crystal
Hongliang Zhang,Ya Wen,Lin Zhang,Zhen Fan,Jinge Liu,Chunting Wu 한국광학회 2019 Current Optics and Photonics Vol.3 No.5
The thermal effect and the light output of a laser crystal under different pumping depths were reported., Based on the thermal model of a single-ended pumped Tm:YAP crystal, the thermal stress coupled model used Comsol to theoretically calculate the effect of changing the pump spot size and pump depth on crystal heat distribution and stress distribution. The experimental results showed that the laser output power first increased and then decreased with increasing pump spot size. As the depth of focus increased, the laser output power first increased and then decreased. The experimental results were consistent with the theoretical simulation results. The theory of pump spot radius and depth of focus in this paper provided an effective simulation method for mitigating thermal effects, and provided theoretical supports for laser crystals to obtain higher laser output power.
Pulsed-laser-diode Intermittently Pumped 2-μm Acousto-optic Q-switched Tm:LuAG Laser
Ya Wen,Yan Jiang,Hao Zheng,Hongliang Zhang,Chao Wang,Chunting Wu,Guangyong Jin 한국광학회 2020 Current Optics and Photonics Vol.4 No.3
The heat distribution in crystals in a 2-µm acousto-optic Q-switched Tm:LuAG laser pumped by pulsed-laser-diode (pulsed-LD) intermittent-pumping technology was analyzed using COMSOL software. The thermal lensing effect of the Tm:LuAG crystal can be mitigated by pulsed-LD intermittent-pumping techniques. An experimental setup using this kind of approach achieved maximum output energy of 8.31 mJ, minimum pulse width of 101.9 ns, and highest peak power of 81.55 kW, reached at a Q-switched repetition rate of 200 Hz. It offers significant improvement of performance of the output laser beam, compared to pulsed-LD double-ended pumping technology at the same repetition rate.