• Title/Summary/Keyword: under-determined system

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Effect of Cold Stratification and Gibberellin Treatment on Androsace septentrionalis L. Seed Germination

  • Dong-Hak Kim;Seungju Jo;Jung-Won Sung;Jung-Won Yoon
    • Korean Journal of Plant Resources
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    • v.36 no.6
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    • pp.580-587
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    • 2023
  • Androsace septentrionalis is a grass species restricted to North Korea; however, it is at the brink of extinction due to habitat loss and environmental changes caused by natural disasters and anthropogenic activities. This study was conducted to characterize the dormancy conditions of A. septentrionalis in an effort to conserve this North Korean plant resource. For this purpose, the morphological characteristics and vigor of A. septentrionalis seeds were examined, and its germination characteristics under different temperature conditions (15/6℃ and 25/15℃ ), low-temperature stratification, and gibberellin (GA3) treatment were determined. The results revealed that A. septentrionalis exhibits non-deep type morpho-physiological dormancy, and low-temperature stratification treatment was not effective in breaking the dormancy of A. septentrionalis seeds. Meanwhile, GA3 treatment significantly increased the mean germination time, rate, and speed of the seeds. The optimal conditions for the germination of A. septentrionalis seeds were 25/15℃ fluctuating temperature and 500 mg·L1 GA3 treatment. The results of this study are useful for the mass propagation of A. septentrionalis.

Evaluation of Sensitivity of a Ferrous Particle Sensor with Variation of Viscosity in Gearbox Systems (기어박스에서 점도의 변화에 의한 철분마모센서의 감도 평가 )

  • Sung-Ho Hong
    • Tribology and Lubricants
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    • v.40 no.4
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    • pp.139-143
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    • 2024
  • This study evaluates the sensitivity of a ferrous particle sensor in response to changes in viscosity in a gearbox. Composed of various gears, the gearbox typically occurs significant ferrous wear due to gear contact. Condition monitoring is primarily implemented by measuring the number of ferrous wear particles in the lubricant. Gearboxes are critical in many systems, including wind turbines, for facilitating changes in speed and torque. Therefore, technology to monitor ferrous particles in gearboxes is essential. In this study, a simplified gearbox is numerically modeled to assess sensor sensitivity based on viscosity and sensor position. Three sensor positions are considered: one directly beneath the gear and two at locations farther from the gear. Analyses are conducted using lubricants with low viscosity and gear oil. Sensor sensitivity is defined by the number of ferrous particles adhering to the sensor, where more particles indicated higher sensitivity. The evaluation reveals that the position directly beneath the gear exhibits the highest sensitivity due to direct influence from the main flow. To achieve optimal sensitivity, sensors should be installed in the main flow path as determined by flow analysis. Evaluation of sensor sensitivity with changes in viscosity shows that a higher viscosity results in a lower sensor sensitivity. Therefore, for ease of analysis, performing an analysis under low-viscosity conditions is useful for understanding the main flow and for identifying the optimal location for proper sensor position.

A Three-dimensional Spectral Model for the Computation of Wind-induced Flows in a Homogeneous Shelf Sea (취송류 재현을 위한 3차원 스펙트랄모형 개발)

  • So, Jae-Kwi;Jung, Kyung-Tae;Lee, Kwang-Soo;Seung, Young-Ho
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.4 no.2
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    • pp.91-107
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    • 1992
  • A numerical formulation is developed to solve the linear three-dimensional hydrodynamic equations which describes wind induced flows in a homogeneous shelf sea. The hydmdynamic equations are at the outset separated into two systems. namely, an equation containing the gradient of sea surface elevation and the mean flow (external mode) and an equation describing the deviation from the mean flow (internal mode). The Galerkin method is then applied to the internal mode equation. The eigenvalues are determined from the eigenvalue problem involving the vertical eddy viscosity subject to a homogeneous boundary condition at the surface and a sheared boundary condition at the sea bed. The model is tested in a one-dimensional channel with uniform depth under a steady, uniform wind. The analytical velocity profile by Cooper and Pearce (1977) using a constant vertical eddy viscosity in channels of infinite and finite length is chosen as a benchmark solution. The model is also tested in a homogeneous, rectangular basin with constant depth under a steady, uniform wind field (the Heaps' Basin of the North Sea scale).

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Effects of Axillary Crutch Length on EMG Activity of the Trunk Muscles and Range of Motion of the Lumbar Spine, Pelvis, and Hip Joint in Healthy Men

  • Kang, Min-Hyeok;Jang, Jun-Hyeok;Kim, Tae-Hoon;Oh, Jae-Seop
    • Physical Therapy Korea
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    • v.20 no.1
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    • pp.55-63
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    • 2013
  • This study investigated the effects of axillary crutch length on trunk muscle activity and lumbo-pelvic-hip complex movements during crutch gait. Eleven healthy men participated in this study. The participants performed a three-point gait with optimal, shorter, and longer crutch lengths. Weight-bearing (WB) side was determined as the dominant leg side. The electromyography (EMG) activity of the bilateral rectus abdominis (RA) and erector spinae (ES) muscles and lumbo-pelvic-hip complex movements were monitored using a three-dimensional motion system with wireless surface EMG. Differences in the EMG activity of RA and ES muscles and range of motion (ROM) of lumbar spine, pelvis, and hip among conditions were analyzed using one-way repeated-measures analysis of variance, and a Bonferroni correction was conducted. There was less RA muscle activity on the WB side under the optimal crutch length condition compared with shorter and longer crutch length conditions (p<.05). The EMG activity of the RA muscle on the non-WB side and ES muscle on the WB side were significantly decreased under the optimal crutch length condition compared with shorter crutch length condition (p<.05). No significant differences in the EMG activity of the ES muscle on the non-WB side and ROM of lumbo-pelvic-hip complex were found among conditions (p>.05). These findings indicate that the optimal crutch length improves the trunk muscle efficiency during crutch gait.

Development of Mono Layer Cell Adsorption Apparatus to Create a Slide for Microscopic Diagnosis (현미경 진단용 슬라이드 제작을 위한 단층세포 흡착장치 개발)

  • Oh, H.Y.;Mun, M.G.;Kim, S.H.;Kim, D.W.;Kang, S.M.;Sung, R.G.;Kim, H.C.
    • Journal of Biomedical Engineering Research
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    • v.36 no.1
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    • pp.1-6
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    • 2015
  • This study aims to design a monolayer cell adsorption apparatus that would help to produce high-quality slides for Liquid-Based Cytology (LBC) of an early cancer diagnosis for human bodies. The LBC collects exfoliated cells of human bodies and spreads the cells on the slides. Through processes of dyeing and cytological examination, the LBC screens for cancers in early stage. In this study, both of a cell suction module and a cell adsorption module, which are the key elements of the monolayer cell adsorption apparatus, were developed, and using those modules, the study set, first, conditions to help both GYN and NON-GYN apply principal cells without de-endothelialization before conducting its own analysis on the utility. As a results, for GYN, apparatus was determined to be able to produce high-quality slides under the condition of 4 and for NON-GYN, the apparatus would come up with other slides of high-quality under the condition of 2. The study carried out a repetitive test on selected conditions and proved 96% of the repetitive success rate. By the results of what has been learned so far, the study presents that the apparatus has a possibility to replace device from South Korea as one of those other currently-applied systems to run the LBC and that the system will also present a new paradigm for cancer diagnosis as it makes a contribution to the improvement in the LBC.

The influence of temperature gradient and rotation rate on Bi4Ge3O12 crystal growth by czochralski method (쵸크랄스키법에 의한 $Bi_4Ge_3O_{12}$ 단결정 육성에서 온도구배와 회전속도가 미치는 영향)

  • 배인국;황진명
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.9 no.6
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    • pp.585-589
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    • 1999
  • In order to grow $Bi_4Ge_3O_{12}$ crystals by the Czochralski method equipped with the auto-diameter control system, we used the resistance heater of our own design. We measure the temperature gradients under-arious thermal configurations. The relation between the critical rotation rate corresponding to the flat interface and the temperature gadient was investigated, and the importance of the axial temperature gradient was pointed out. The results from this work were compared with those obtained by other authors when RF heating was used. The optimal conditions for the crystal growth were determined as follows; under $O_2$ atmosphere with the pulling rate fixed at 2 mm/hr, rotation rate changed from 30 to 23 rpm as the crystal growth proceeded, radial and axial temperature gradients were 50 and $40^{\circ}C$/cm near melts respectively, and the composition was chemically stoichiometric.

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Photocatalysis of o-, m- and p-Xylene Using Element-Enhanced Visible-Light Driven Titanium Dioxide

  • Kim, Jong-Tae;Kim, Mo-Keun;Jo, Wan-Kuen
    • Journal of Environmental Science International
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    • v.17 no.11
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    • pp.1195-1201
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    • 2008
  • Enhancing with non-metallic elemental nitrogen(N) is one of several methods that have been proposed to modify the electronic properties of bulk titanium dioxide($TiO_2$), in order to make $TiO_2$ effective under visible-light irradiation. Accordingly, current study evaluated the feasibility of applying visible-light-induced $TiO_2$ enhanced with N element to cleanse aromatic compounds, focusing on xylene isomers at indoor air quality(IAQ) levels. The N-enhanced $TiO_2$ was prepared by applying two popular processes, and they were coated by applying two well-known methods. For three o-, m-, and p-xylene, the two coating methods exhibited different photocatalytic oxidation(PCO) efficiencies. Similarly, the two N-doping processes showed different PCO efficiencies. For all three stream flow rates(SFRs), the degradation efficiencies were similar between o-xylene and m,p-xylene. The degradation efficiencies of all target compounds increased as the SFR decreased. The degradation efficiencies determined via a PCO system with N-enhanced visible-light induced $TiO_2$ was somewhat lower than that with ultraviolet(UV)-light induced unmodified $TiO_2$, which was reported by previous studies. Nevertheless, it is noteworthy that PCO efficiencies increased up to 94% for o-xylene and 97% for the m,p-xylene under lower SFR(0.5 L $min^{-1}$). Consequently, it is suggested that with appropriate SFR conditions, the visible-light-assisted photocatalytic systems could also become important tools for improving IAQ.

Effects of Reactive Oxygen Species on the Function of Porcine Spermatozoa (활성산소계가 돼지 정자의 기능에 미치는 영향)

  • Kim, Byung-Gak;Kim, Ki-Jung;Lee, Yong-An;Kim, Bang-Jin;Kim, Yong-Hee;Ryu, Buom-Yong
    • Reproductive and Developmental Biology
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    • v.33 no.1
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    • pp.49-54
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    • 2009
  • The current study was designed to evaluate the effects of the reactive oxygen species (ROS) generated with a xanthine (X) and xanthine oxidase system (XO) on sperm function and DNA fragmentation in porcine spermatozoa. ROS were produced by a combination of $1,000{\mu}M$ X and 50 mU/ml XO. The ROS scavengers such as superoxide dismutase (SOD) (200 U/ml) and catalase (CAT) (500 U/ml) were also tested. Spermatozoa were incubated for 2 hours in BWW medium with a combination of X-XO supplemented with or without antioxidants at $37^{\circ}C$ under 5% $CO_2$ incubator. Ca-ionophore-induced acrosome reaction, the proportion of swollen spermatozoa under hypo-osmotic condition, malondialdehyde formation for the analysis of lipid peroxidation, and the proportion of DNA fragmentation were determined after 2 hours incubation. The action of ROS on porcine spermatozoa resulted in decreased Ca-ionophore-induced acrosome reaction and membrane integrity, increased the formation of malondialdehyde, and the proportion of sperm with DNA fragmentation(p<0.05). The toxic effects caused by ROS were completely alleviated by CAT in terms of sperm function and characteristics, however SOD did not serve the same scavenger effect as CAT. To conclude, the ROS can cause significant damage to porcine sperm functions and characteristics, which can be minimized by the use of antioxidants.

Study of the Rheological Properties of a Fermentation Broth of the Fungus Beauveria bassiana in a Bioreactor Under Different Hydrodynamic Conditions

  • Nunez-Ramirez, Diola Marina;Medina-Torres, Luis;Valencia-Lopez, Jose Javier;Calderas, Fausto;Lopez-Miranda, Javier;Medrano-Roldan, Hiram;Solis-Soto, Aquiles
    • Journal of Microbiology and Biotechnology
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    • v.22 no.11
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    • pp.1494-1500
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    • 2012
  • Fermentation with filamentous fungi in a bioreactor is a complex dynamic process that is affected by flow conditions and the evolution of the rheological properties of the medium. These properties are mainly affected by the biomass concentration and the morphology of the fungus. In this work, the rheological properties of a fermentation with the fungus Beauveria bassiana under different hydrodynamic conditions were studied and the rheological behavior of this broth was simulated through a mixture of carboxymethyl cellulose sodium and cellulose fibers (CMCNa-SF). The bioreactor was a 10 L CSTR tank operated at different stir velocities. Rheological results were similar at 100 and 300 rpm for both systems. However, there was a significant increase in the viscosity accompanied by a change in the consistence index, calculated according to the power law model, for both systems at 800 rpm. The systems exhibited shear-thinning behavior at all stir velocities, which was determined with the power law model. The mixing time was observed to increase as the cellulose content in the system increased and, consequently, the efficiency of mixing diminished. These results are thought to be due to the rheological and morphological similarities of the two fungal systems. These results will help in the optimization of scale-up production of these fungi.

A Study on the Hazardousness Evaluation and the Inhalation Toxicity of Methylcyclohexane (메틸사이클로핵산 (methylcyclohexane)의 흡입독성과 유해성 평가)

  • Kim Hyeon-Yeong;Lee Sung-Bae;Kang Min-Gu;Song Si-Hwan
    • Environmental Analysis Health and Toxicology
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    • v.21 no.2 s.53
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    • pp.173-184
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    • 2006
  • From the harmfulness expectation test conducted through a toxicity anticipation program, methylcyclohexane turned out to be harmful and simulative, but no carcinogenicity was anticipated. In a four-hour acute inhalation toxicity test, the result showed that lethal concentration ($LC_{50}$) was 3,750 ppm (15,054 mg/L), which was identified as a harmful substance on the basis of the harmful substance classification standard $2 of the Industrial safety and health law. methylcyclohexane fell under the category $4(2,500 substance from the GHS standard acute toxicity harmfulness classification. Also, from subchronic inhalation toxicity test that included 6 hours a day, five days a week, and for 13 weeks, we could observe weight, activity, long term weight, blood and blood biochemical influence from the exposure of test substance. No-observed effect level (NOEL) was determined below $100{\sim}400ppm$ inboth male and female. This material falls under the Category 2 ($50{\sim}250ppm/6hours/90days$) in the GHS (Globally Harmonized System) standard trace long-term whole body toxicity repeated exposure, and can be classified as a harmful substance in accordance with the Industrial Safety and Health Law harmful substance standard $NOEL{\leq}0.5mg/L/6hr/90day$ (rat).