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Journal of Environmental Sciences 2010年第6期22卷 846-850页

作者： Kyung Hwa Cho Dukki Han Yongeun Park Seung Won Lee Sung min cha Joo-Hyon Kang Joon Ha Kim Department of Environmental Science and Engineering Gwangju Institute of Science and Technology Deparment of Civil and Environmental Engineering Dongguk University-Seoul Sustainable Water Resource Technology Center Gwangju Institute of Science and Technology

Most probable number （MPN） and colony-forming unit （CFU） estimates of fecal indicator bacteria （FIB） concentration are common measures of water quality in aquatic environments. Thus, FIB intensively monitored in Yeongsan Watershed in an attempt to compare two different methods and to develop a statistical model to convert from CFU to MPN estimates or vice versa. As a result, the significant difference was found in the MPN and CFU estimates. The enumerated Escherichia coli concentrations in MPN are greater than those in CFU, except for the measurement in winter. Especially in fall, E. coli concentrations in MPN are one order of magnitude greater than that in CFU. Contrarily, enterococci bacteria in MPN are lower than those in CFU. however, in general, a strongly positive relationship are found between MPN and CFU estimates. Therefore, the statistical models were developed, and showed the reasonable converting FIB concentrations from CFU estimates to MPN estimates. We expect this study will provide preliminary information towards future research on whether different analysis methods may result in different water quality standard violation frequencies for the same water sample.

关键词： most probable number colony-forming unit fecal indicator bacteria Escherichia coli enterococci

A theoretical and 1-D numerical investigation on a valve/valveless air-breathing pulse detonation engine

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Chinese Journal of Aeronautics 2021年第1期34卷 68-78页

作者： Hua QIU cha XIONG Jianling LI School of Power and Energy Northwestern Polytechnical UniversityXi'an 710072China State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing 100081China

The important operating characteristics of pulsed Pressure Gain Combustion(PGC)propulsion are the pressure gain of the combustor component and the propulsive performance gain of the engine.A ramjet-type valve/valveless air-breathing pulsed detonation engine with a supersonic internal compression inlet is *** on an ideal thermal cycle,the ideal equivalent pressure ratios(pcb)of the Pulsed Detonation Combustor(PDC)are obtained theoretically which are directly related with the propulsive performance of the *** introducing an orifice loss model into the cycles,the critical pressure drop ratios through the orifice for the PDC achieving pressure gain and the engine achieving thrust gain are *** influencing factors are investigated by the use of a one-dimensional(1-D)numerical simulation *** operating characteristics of the pulse detonation engine are investigated with changes of the valve type,the inlet/outlet area ratio of the PDC,the nozzle area ratio,and flight *** these factors can affect pcbof the PDC,and pcbcan be optimized by changing the geometry of the *** most important influence parameter is the valve *** using an orifice-type aerodynamic valve,simulation results show that the PDC cannot achieve the pressure gain *** a supersonic internal compression inlet is introduced to the engine,whether the Pulse Detonation Engine(PDE)can achieve thrust gain comparable with that of an ideal Brayton cycle engine not only is related to the pressure gain of the combustor,but also needs to optimize the engine structure to reduce the total pressure loss.

关键词： Detonation Pressure gain characteristics Propulsive performance Supersonic internal compression inlet Valve/valveless Thermal cycle

Conception and Design of Active Balancer for Planar Mechanisms

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Chinese Journal of Mechanical Engineering 2009年第6期22卷 822-832页

作者： ZHANG Ying YAO Yan-An cha Jianzhong School of Mechanical and Electronic Control Engineering Beijing Jiaotong University Beijing 100044 China

The dynamic balancing is an important issue in mechanism design. For the existing balancing methods, both passive and active ones, there is still room for improvement in adaplability and independency. In view of this, a concept of active balancer is developed as a new solution for the dynamic balancing with more flexibility. The proposed balancer is an independent additional device with a control system inside, which consists of a two-degree-of-freedom （DOF） linkage and a controllable motor, and can be attached to a machine expediently with little change to its original structure and motion. One of the two inputs of the two-DOF linkage shares the same shaft with its output, which is connected to the input shaft of a machine to be balanced and driven by the original actuator. The other input is driven by the control motor. By properly selecting the speed trajectories of the control motor and link parameters of the two-DOF linkage, one or more dynamic effects of the mechanisms can be minimized or eliminated adaptively. The design procedure of the active balancer is put forward and a two-step optimization is developed to find out optimal design parameters of the balancer for various design requirements and constraints. Taking a force-balanced crank-rocker mechanism as the reference mechanism, numerical examples are given to illustrate the design procedure. The balancing effects of the proposed balancer are compared with those of the existing adding dyads （DYAD） method. The results show that the introduction of the control system provides the active balancer with better balancing effect and more flexibility than the DYAD method. A considerable reduction in the dynamic effects （input torque, shaking moment and shaking force） can be achieved for different balancing object by designing the structural and control parameters of the balancer, and the deterioration of dynamic performance caused by alterative working conditions can be compensated effectively by redesigning the

关键词： active balancing shaking moment input torque shaking force optimum balancing two-degree-of-freedom linkage

Intra and extra pelvic multidisciplinary surgical approach of retroperitoneal sarcoma:Case series report

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World Journal of Clinical Cases 2022年第27期10卷 9693-9702页

作者： Heekyoung Song Jung Hwan Ahn Yuyeon Jung Jae Yeon Woo Jimin cha Yang-Guk Chung Keun ho Lee Department of Obstetrics and Gynecology Incheon St.Mary’s HospitalCollege of MedicineThe Catholic University of KoreaSeoul 06591South Korea Department of Obstetrics and Gynecology Seoul St.Mary’s HospitalCollege of MedicineThe Catholic University of KoreaSeoul 06591South Korea Department of Orthopaedic Surgery Seoul St.Mary’s HospitalCollege of MedicineThe Catholic University of KoreaSeoul 06591South Korea

BACKGROUND Retroperitoneal sarcoma(RPS) is a rare malignancy arising from mesenchymal cells that most commonly presents as an abdominal mass and is associated with poor *** several studies have assessed the survival benefits of wide excision,few have reported detailed methods for achieving wide excision in patients with *** To describe our experience with multidisciplinary surgical resection of RPS using intra-and extra-pelvic *** Multidisciplinary surgery is an anatomical approach that combines intra-and extra-peritoneal access within the same surgery to achieve complete RPS *** retrospective review of the records of patients who underwent multidisciplinary surgery for RPS analyzed surgical and survival *** Eight patients underwent 10 intra-and extra-pelvic surgical resections,and their median mass size was 12.75 cm(range,6-45.5 cm).Using an intrapelvic approach,laparoscopy-assisted surgery was performed in four cases and laparotomy surgery in *** an extrapelvic approach,ilioinguinal and posterior approaches were used in four cases each,and the prone position and midline skin incision were shared in *** patients’ RPS masses were removed completely,and four achieved R0 resection through intra-and extra-pelvic *** median estimated blood loss was 2000 m L(range,300-20000 m L) and the median hospitalization was 12.6 d(range,9-69 d).Reoperation was needed in two patients(one for wound necrosis and the other for bowel perforation and wound necrosis).The median overall survival rate and median progression-free survival were 64.6 and 13.7 mo,*** RPS is therapeutically challenging because of its location and high risk of ***,intra-and extra-pelvic surgical approaches can improve the macroscopic security of the surgical margin.

关键词： Margins of excision Retroperitoneal neoplasms Sarcoma

Variations in dynamic recrystallization behavior and mechanical properties of AZ31 alloy with extrusion temperature

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Journal of Magnesium and Alloys 2023年第7期11卷 2351-2365页

作者： Jae Won cha Sung Hyuk Park School of Materials Science and Engineering Kyungpook National UniversityDaegu 41566Republic of Korea

This study investigates the effects of extrusion temperature on the dynamic recrystallization(DRX)behavior of a Mg-3Al-1Zn-0.3Mn(AZ31,wt%)alloy during hot extrusion and on the microstructural characteristics and mechanical properties of materials extruded at 350 and 450℃.An increase in the extrusion temperature causes a decrease in the amount of strain energy accumulated in the material during extrusion,because of promoted activation of pyramidalslip and dynamic *** reduced strain energy weakens the DRX behavior during extrusion,which eventually results in a decrease in the area fraction of recrystallized grains of the extruded *** material extruded at 450℃has coarser grains and a stronger basal fiber texture than that extruded at 350℃.As the extrusion temperature increases from 350 to 450℃,the tensile yield strength(TYS)of the extruded material increases from 191.8 to 201.5 MPa,whereas its compressive yield strength(CYS)decreases from 122.5 to 111.0 MPa;consequently,its tension-compression yield stress ratio(CYS/TYS)decreases from 0.64 to *** increase in the TYS is attributed mainly to the stronger texture hardening and strain hardening effects of the extruded material,and the decrease in the CYS is attributed to the reduced twinning stress resulting from grain coarsening and texture *** microstructural and textural evolutions of the materials during extrusion and the deformation and hardening mechanisms of the extruded materials are discussed in detail.

关键词： Mg-Al-Zn alloy Extrusion Dynamic recrystallization Microstructure Yield asymmetry

Prediction of liver cirrhosis, using diagnostic imaging tools

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World Journal of Hepatology 2015年第17期7卷 2069-2079页

作者： Suk Keu Yeom chang Hee Lee Sang hoon cha Cheol min Park Department of Radiology Korea University Ansan Hospital Korea University College of Medicine Department of Radiology Korea University Guro Hospital

Early diagnosis of liver cirrhosis is important. Ultrasoundguided liver biopsy is the gold standard for diagnosis of liver cirrhosis. however, its invasiveness and sampling bias limit the applicability of the method. Basic imaging for the diagnosis of liver cirrhosis has developed over the last few decades, enabling early detection of morphological changes of the liver by ultrasonography(US), computed tomography, and magnetic resonance imaging(MRI). They are also accurate diagnostic methods for advanced liver cirrhosis, for which early diagnosis is difficult. There are a number of ways to compensate for this difficulty, including texture analysis to more closely identify the homogeneity of hepatic parenchyma, elastography to measure the stiffness and elasticity of the liver, and perfusion studies to determine the blood flow volume, transit time, and velocity. Amongst these methods, elastography using US and MRI was found to be slightly easier, faster, and able to provide an accurate diagnosis. Early diagnosis of liver cirrhosis using MRI or US elastography is therefore a realistic alternative, but further research is still needed.

关键词： Liver fibrosis Ultrasonography Computedtomography Magnetic resonance imaging Magneticresonance elastography Sonoelastography Acousticradiation force impulse imaging

Removal of primary iron rich phase from aluminum-silicon melt by centrifugal separation

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China Foundry 2013年第2期10卷 112-117页

作者： Seong Woo Kim Un ho Im Hyeong Cheol cha Se Hyeong Kim Ji Eun Jang Ki Young Kim School of Energy Materials and Chemical EngineeringKorea University of Technology and Education

Recycling is a major consideration in continued aluminum use due to the enormous demand for high quality products. Some impurity elements gradually accumulate through the repetitive reuse of aluminum alloy scrap. Of them, the iron content should be suppressed under the allowed limit. In the present research, a novel separation method was introduced to remove primary iron-rich intermetallic compounds by centrifugation during solidification of AI-Si-Fe alloys. This method does not use the density difference between two phases as in other centrifugal methods, but uses the order of solidification in AI-Si-Fe alloys, because iron promotes the formation of intermetallic compounds with other alloying elements as a primary phase. Two AI-Si-Fe alloys which have different iron contents were chosen as the starting materials. The iron-rich phase could be efficiently removed by centrifuging under a centrifugal force of 40 g. Coarse intermetallic compounds were found in the sample inside the crucible, while rather fine intermetallic compounds were found in the sample outside the crucible. Primary intermetallic compounds were linked to each other via aluminum-rich matrix, and formed like a network. The highest iron removal fraction is 67% and the lowest one is 7% for AI-12Si-1.7Fe alloy. And they are 82% and 18% for AI-12Si-3.4Fe alloy, respectively.

关键词： Al-Si alloys iron removal centrifugal separation

Posterior propriety in nonparametric mixed efects model

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Applied Mathematics(A Journal of Chinese Universities) 2013年第3期28卷 369-378页

作者： XU An-cha TANG Yin-cai College of Mathematics and Information Science Wenzhou University School of Finance and Statistics East China Normal University

It is well known that spline smoothing estimator relates to the Bayesian estimate under partially informative normal prior. In this paper, we derive the conditions for the pro- priety of the posterior in the nonparametric mixed effects model under this class of partially informative normal prior for fixed effect with inverse gamma priors on the variance compo- nents and hierarchical priors for covariance matrix of random effect, then we explore the Gibbs sampling procedure.

关键词： nonparametric mixed effect model Bayesian spline smoothing Gibbs sampling.

Comparison of the efficacy and safety of once-daily dosing and on-demand use of udenafil for type 2 diabetic patients with erectile dysfunction

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Asian Journal of Andrology 2015年第1期17卷 143-148,I0011,I0012页

作者： Soon Hyun Park Sung Woo Park Bong Yun cha Ie Byung Park Kyung Wan min Yeon Ah Sung Tae Hwa Kim Jae min Lee Kang Seo Park Department of Internal Medicine Eulji University School of Medicine Daejeon 302-799 South Korea Department of Endocrinology and Metabolism Kangbuk Samsung Hospital Sungkyunkwan University School of Medicine Seou1110-746 South Korea Department of Endocrinology and Metabolism College of Medicine the Catholic University of Korea Seou1137-701 South Korea Department of Internal Medicine Gachon University of Medicine and Science Graduate School of Medicine Incheon 405-760 South Korea Department of Internal Medicine Eulji University School of Medicine Seou1139-872 South Korea Department of Endocrinology Ewha Woman's University School of Medicine Seoul 158-710 South Korea Department of Internal Medicine College of Medicine Hanyang University Seoul 133-792 South Korea.

We compared the efficacy and safety between once-daily dosing and on-demand use of udenafil for type 2 diabetic patients with erectile dysfunction （ED）. A multi-center, randomized, open-label, parallel-group, 12-week study was conducted. 161 patients who improved with on-demand 200 mg of udenafil according to Sexual Encounter Profile （SEP） diary Question 2 and 3 （Q2 and Q3） were randomized into 200 mg on-demand （n = 80） or 50 mg once-daily （n = 81） dosing groups for 8 weeks. The dosing period was followed by a 4-week treatment-free period. The primary efficacy endpoint was the change of the International Index of Erectile Function （IIEF） erectile function domain （EFD） score. The secondary efficacy endpoints included changes to the SEP diary Q2, Q3, IIEF Q3, Q4, other domains of IIEF, Global Assessment Question, and shift to the normal rate （EFD 〉 26）. Vascular endothelial markers were also assessed. The IIEF-EFD score of both groups improved after 8 weeks of treatment （P 〈 0.0001）. There was no statistically significant difference between two groups. Improvement was not maintained after the treatment-free follow-up period. Similar results were observed in the secondary efficacy endpoints. There was also no significant difference in vascular endothelial markers. Daily udenafil was well-tolerated, and there was no significant difference in the adverse drug reactions and adverse events between the two groups. Flushing and headache were the most frequent adverse events. Both regimens improved ED in diabetic patients and were well-tolerated. Further studies are needed to assess the effect of daily udenafil treatment in diabetic patients.

关键词： erectile dysfunction International Index of Erectile Function once-daily dosing ptiosphodiesterase type 5 inhibitor type 2 diabetes mellitus udenafil

Proline Accumulation,Photosynthetic Abilities and Growth characters of Sugarcane(Saccharum officinarum L.) Plantlets in Response to Iso-Osmotic Salt and Water-Deficit Stress

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Agricultural Sciences in China 2009年第1期8卷 51-58页

作者： Suriyan cha-um chalermpol Kirdmanee National Center for Genetic Engineering and Biotechnology(BIOTEC) National Science and Technology Development Agency(NSTDA)

The aim of this study was to investigate the biochemical, physiological and morphological responses of sugarcane to iso- osmotic salt and water-deficit stress. Disease-free sugarcane plantlets derived from meristem cuttings were photo- autotrophically grown in MS media and subsequently exposed to -0.23 （control）, -0.67 or -1.20 MPa iso-osmotic NaCl （salt stress） or mannitol （water-deficit stress）. Chlorophyll a （Chl a）, chlorophyll b （Chl b）, total carotenoids （Cx＋c）, maximum quantum yield of PSII （Fv/Fm）, photon yield of PSII （ΦPSII）, stomatal conductance （Gs） and transpiration rate （E） in the stressed plantlets were significantly reduced when compared to those of plantlets of the control group （without mannitol or NaCl）, leading to net-photosynthetic rate （Pn） and growth reduction with positive correlation. In addition, physiological changes and growth parameters of plantlets in the salt stress conditions were more sharply reduced than those in waterdeficit stress conditions. On the other hand, the proline content and non-photochemical quenching （NPQ） in the leaves of stressed plantlets increased significantly, especially in response to iso-osmotic salt stress. The chlorophyll pigments in iso-osmotic stressed leaves were significantly degraded （r^2 = 0.93）, related to low water oxidation （r^2 = 0.87）, low net- photosynthetic rate （r^2 = 0.81）, and growth reduction （r^2 = 0.97）. The multivariate biochemical, physiological and growth parameters in the present study should be further used to develop salt, or drought, tolerance indices in sugarcane breeding programs.

关键词： growth performances net-photosynthetic rate pigment degradation proline water oxidation