检索结果-南通市图书馆

Efficient multi-response adaptive sampling algorithm for construction of variable-fidelity aerodynamic tables

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2019年第3期32卷 547-558页

作者： Maxim TYAN jae-woo LEE Department of Aerospace Information Engineering Konkuk University

Adaptive sampling is an iterative process for the construction of a global approximation model. Most of engineering analysis tools computes multiple parameters in a single run. This research proposes a novel multi-response adaptive sampling algorithm for simultaneous construction of multiple surrogate models in a time-efficient and accurate manner. The new algorithm uses the Jackknife cross-validation variance and a minimum distance metric to construct a sampling criterion function. A weighted sum of the function is used to consider the characteristics of multiple surrogate models. The proposed algorithm demonstrates good performance on total 22 numerical problems in comparison with three existing adaptive sampling algorithms. The numerical problems include several two-dimensional and six-dimensional functions which are combined into singleresponse and multi-response systems. Application of the proposed algorithm for construction of aerodynamic tables for 2 D airfoil is demonstrated. Scaling-based variable-fidelity modeling is implemented to enhance the accuracy of surrogate modeling. The algorithm succeeds in constructing a system of three highly nonlinear aerodynamic response surfaces within a reasonable amount of time while preserving high accuracy of approximation.

关键词： Adaptive sampling Aerodynamic database Multi-response system Surrogate modeling Variable fidelity modeling

Grade-4 commercially pure titanium with ultrahigh strength achieved by twinning-induced grain refinement through cryogenic deformation

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2021年第7期66卷 193-201页

作者： Seong-woo Choi jae Sukjeong Jong woo Won jae Keun Hong Yoon Suk Choi Titanium Department.Korea Institute of Materials Science Changwon51508Republic of Korea School of Materials Science and Engineering Pusan National UniversityPusan.46241Republic of Korea Materials and Manufacturing Development Team Doosan Heavy Industries and ConstructionChangwon51711Republic of Korea

The yield strength of commercially pure(CP) Ti of ASTM grade 4, the strongest among all the CP-Ti grades, is too low for structural applications that require high-strength materials. Here, we demonstrate the strengthening of grade-4 CP Ti by cryogenic-temperature rolling(CTR), which enables deformation twinning in grade-4 CP Ti to achieve twinning-induced grain refinement. CTR activated {11.22} twinning and {10.12} twinning, which are the most common twinning systems in pure Ti, whereas room-temperature rolling(RTR) did not activate any twinning system. CTR with imposing an area reduction of just 30% significantly increased the yield strength of the CP Ti to 946 MPa, which is not achievable through typical processes performed at or above room temperature and is comparable to that of commercial Ti-6 Al-4 V. The significant increase in strength was due to microstructural strengthening caused by twinning-induced grain refinement, combined with dislocation accumulation. In contrast to RTR, CTR greatly increased the stress concentration at grain boundaries(GBs), which caused the unusual activation of twinning in the grade-4 CP Ti by facilitating twin nucleation at GBs. The stress concentration increased because CTR activated the slip to a lesser extent compared to RTR, thereby reducing the strain compatibility between neighboring grains. These results will contribute to development of ultrahigh-strength CP Ti and may thereby extend its use to structural applications that require high-strength materials.

关键词： Titanium Twinning Cryogenic deformation Grain refinement Tensile properties

k-Nearest Neighbor Query Processing Algorithms for a Query Region in Road Networks

在线全文

学校读者我要写书评

暂无评论

Journal of Computer Science & Technology 2013年第4期28卷 585-596页

作者： Hyeong-Il Kim jae-woo Chang Department of Computer Engineering Chonbuk National University Cloud Open R&D Center Chonbuk National University

Recent development of wireless communication technologies and the popularity of smart phones .are making location-based services （LBS） popular. However, requesting queries to LBS servers with users＇ exact locations may threat the privacy of users. Therefore, there have been many researches on generating a cloaked query region for user privacy protection. Consequently, an efficient query processing algorithm for a query region is required. So, in this paper, we propose k-nearest neighbor query （k-NN） processing algorithms for a query region in road networks. To efficiently retrieve k-NN points of interest （POIs）, we make use of the Island index. We also propose a method that generates an adaptive Island index to improve the query processing performance and storage usage. Finally, we show by our performance analysis that our k-NN query processing algorithms outperform the existing k-Range Nearest Neighbor （kRNN） algorithm in terms of network expansion cost and query processing time.

关键词： island index k-nearest neighbor query processing scheme locatiombased service road network

Segregation of voiced and unvoiced components from residual of speech signal

在线全文

学校读者我要写书评

暂无评论

Journal of Central South University 2012年第2期19卷 496-503页

作者： JO Cheol-woo KIM jae-hee School of Mechatronics Changwon National University

In conventional source-filter models, voiced and unvoiced components were considered independently. However, in practice it was difficult to separate the source into two parts. An actual source consists of a mixture of two sources and the ratio varies according to the content or the intention of speaker. It had been investigated to separate the voiced and unvoiced components for different source models. Source signals were modeled based on the residual signal measured from inverse filtering. Three different source models were assumed. The parameters of each model were optimized for the original speech signal using a genetic algorithm. The resulting parameters were compared in terms of the mel-cepstral distance to the original signal, the spectrogram and the spectral envelope from the synthesized signal. The optimization method achieves an improvement of 15% for the Klatt model, but there is little improvement in the modified residual case.

关键词： voice source model synthesis optimization genetic algorithm

Biomass seaweed-derived n itrogen self-doped porous carb on anodes for sodium-ion batteries:Insights into the structure and electrochemical activity

在线全文

学校读者我要写书评

暂无评论

Journal of Energy Chemistry 2022年第1期31卷 286-295,I0008页

作者： Chenrayan Senthil jae woo Park Nitheesha Shaji Gyu Sang Sim Chang woo Lee Department of Chemical Engineering(Integrated Engineering)&Center for the SMART Energy Platform College of EngineeringKyung Hee University1732 Deogyeong-daeroCihuengYonginGyeonggi 17104South Korea

Sustainable transformation and efficient utilization of biomasses and their derived materials are environ-mentally as well as economically compliant *** seaweed-derived nitrogen self-doped porous carbon with tailored surface area and pore structures are prepared through carb on izatio n and *** in fluence of carb on ization temperature on morphology,surface area,and heteroatom dopants are investigated to optimize sodium-ion storage ***-derived nitrogen selfdoped activated carbon(SAC)as anode materials for sodium-ion batteries exhibits remarkable reversible capacity of 303/192 mAh g^(-1) after 100/500 cycles at current densities of 100/200 mA g^(-1) respectively,and a good rate *** interconnected and porous conducting nature along with the heteroatom dopant role in creating defective sites and charge stabilization are favorable for ion storage and diffusion and electron transport,indicating the electrodes can offer improved electrochemical *** addition,post-mortem analysis of the cycled carbon electrodes through ex-situ tools demonstrates the sodium-ion storage mechanism.

关键词： Biomass Heteroatom self-doping Porous carbon Anode Sodium-ion batteries Post-mortem ex-situ analysis

Decomposition kinetics of dimethyl methylphospate(chemical agent simulant) by supercritical water oxidation

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2006年第1期18卷 13-16页

作者： Bambang VERIANSYAH jae-Duck KIM Youn-woo LEE Supercritical Fluid Research Laboratory Korea Institute of Science and Technology(KIST) 39-1 Hawolgok-dong Seoungbuk-gu Seoul 136-791 Korea. School of Chemical and Biological Engineering Seoul National University(SNU) San 56-1 Sillim-dong Gwanak-gu Seoul 151-744 Korea

Supercritical water oxidation （SCWO） has been drawing much attention due to effectively destroy a large variety of high-risk wastes resulting from munitions demilitarization and complex industrial chemical. An important design consideration in the development of supercritical water oxidation is the information of decomposition rate. In this paper, the decomposition rate of dimethyl methylphosphonate（DMMP）, which is similar to the nerve agent VX and GB（Sarin） in its structure, was investigated under SCWO conditions. The experiments were performed in an isothermal tubular reactor with a H2O2 as an oxidant. The reaction temperatures were ranged from 398 to 633℃ at a fixed pressure of 24 MPa. The conversion of DMMP was monitored by analyzing total organic carbon （TOC） on the liquid effluent samples. It is found that the oxidative decomposition of DMMP proceeded rapidly and a high TOC decomposition up to 99.99% was obtained within 11 s at 555℃. On the basis of data derived from experiments, a global kinetic equation for the decomposition of DMMP was developed. The model predictions agreed well with the experimental data.

关键词： supercritical water oxidation kinetics chemical agent DMMP

Aerodynamic design optimization of helicopter rotor blades including airfoil shape for hover performance

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2013年第1期26卷 1-8页

作者： Ngoc Anh Vu jae woo Lee Jung Il Shu Department of Aerospace Engineering Ho Chi Minh City University of Technology Department of Aerospace Information Engineering Konkuk University

This study proposes a process to obtain an optimal helicopter rotor blade shape for aerodynamic performance in hover flight. A new geometry representation algorithm which uses the class function/shape function transformation （CST） is employed to generate airfoil coordinates. With this approach, airfoil shape is considered in terms of design variables. The optimization process is constructed by integrating several programs developed by author. The design variables include twist, taper ratio, point of taper initiation, blade root chord, and coefficients of the airfoil distribution function. Aerodynamic constraints consist of limits on power available in hover and forward flight. The trim condition must be attainable. This paper considers rotor blade configuration for the hover flight condition only, so that the required power in hover is chosen as the objective function of the optimization problem. Sensitivity analysis of each design variable shows that airfoil shape has an important role in rotor performance. The optimum rotor blade reduces the required hover power by 7.4% and increases the figure of merit by 6.5%, which is a good improvement for rotor blade design.

关键词： Airfoil Design optimization Helicopter design Hover performance Planforms Rotor blades design

Anesthetics management of a renal angiomyolipoma using pulse pressure variation and non-invasive cardiac output monitoring: A case report

在线全文

学校读者我要写书评

暂无评论

World Journal of Clinical Cases 2022年第24期10卷 8656-8661页

作者： woo jae Jeon woo Jong Shin Young Joon Yoon Chan woo Park jae Hang Shim Sang Yun Cho Department of Anesthesiolgy and Pain Medicine Hanyang University Guri HospitalGuri-si 471-701Gyeonggi-doSouth Korea

BACKGROUND Hypovolemic shock can lead to life-threatening organ dysfunction,and adequate fluid administration is a fundamental ***,parameters such as vital signs,central venous pressure,and urine output have been used to estimate intravascular ***,pulse pressure variation(PPV)and non-invasive cardiac monitoring devices have been *** this case report,we introduce a patient with massive active bleeding from giant renal angiomyolipoma(AML).During emergent nephrectomy,we used non-invasive cardiac monitoring with CSN-1901(Nihon Kohden,Tokyo,Japan)and PPV to evaluate the patient's intravascular volume status to achieve optimal fluid *** SUMMARY A 30-year-old male patient with giant AML with active bleeding was referred to the emergency room complaining of severe abdominal pain and spontaneous abdominal *** was diagnosed by computed tomography,and emergent nephrectomy was *** bleeding was expected so we decided to use non-invasive cardiac monitoring and PPV to assist fluid therapy because they are relatively easy and fast compared to invasive cardiac *** the surgery,6000 mL of estimated blood loss *** with the patient's vital signs and laboratory results,we monitored cardiac output,cardiac output,stroke volume,stroke volume index with a non-invasive cardiac monitoring device,and PPV using an intra-arterial catheter to evaluate intravascular volume status of the patient to compensate for massive *** In addition to traditional parameters,non-invasive cardiac monitoring and PPV are useful methods to evaluate patient's intravascular volume status and provideguidance for intraoperative management of hypovolemic shock patients.

关键词： Renal angiomyolipoma Pulse pressure variation Cardiac output Case report

Investigating the Calculation of Rotational Viscosity of the Mixture Comprising Different Kinds of Liquid Crystals： Molecular Dynamics Computer Simulation Approach

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Chemistry 2011年第1期29卷 48-52页

作者： Kim, Jinsoo Jamil, Muhammad Jung, jae Eun Jang, jae Eun Farzana, Ahmad Jin, woo Lee Sang, woo Park woo, Min-Kyung Kwak, Ji Yeon Jeon, Young-jae Liquid Crystal Research Centre Department of Chemistry Konkuk University 143-701 Seoul Korea Division of International Affairs University College Konkuk University 143-701 Seoul Korea Samsung Advanced Institute of Technology (SAID) Yongin-shi Gyeonggi-do 446-712 Korea

Molecular dynamics （MD） computer simulation techniques, as a powerful tool commonly utilized by the liquid crystal display （LCD） community, usually are employed for computing the equilibrium and transport properties of a classical many body system, since they are very similar to real experiments in many respects. In this paper we pre- sent molecular dynamics computer simulation results taken for a mixture of the two different kinds of nematic liq- uid crystals （LCs）. We calculated rotational viscosity from Brownian behavior with friction of the mean director of the mixture comprising pentylcyanobiphenol （5CB） and decylcyanobiphenol （10CB） by using molecular dynamics computer simulation, where intermolecular potential parameter is Generalized AMBER force field （GAFF）. Our computed results show a good agreement with the experimental results.

关键词： liquid crystal mixture ab initio calculations rotational viscosity generalized AMBER force field(GAFF) molecular dynamics simulation nematic liquid crystals computer simulation