• Title/Summary/Keyword: NAT behavior

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Rheological Properties of Gelatinized Potato Starch (겔라틴화(化)된 감자 전분(澱粉)의 리올로지 특성(特性))

  • Chang, Young Il;Chang, Kyu Seob;Park, Young Duck
    • Korean Journal of Agricultural Science
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    • v.18 no.1
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    • pp.41-48
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    • 1991
  • Rheological properties of gelatinized potato starch were investigated with Brookfield wide-gap viscometer at various conditions. The gelatinized potato starch at 3-7% showed a pseudoplastic behavior with yield stress, and presented thixotropic properties with time-dependent structural decays. The consistency index and yield stress of gelatinized starch were proportional to starch concentration but inversely proportional to measurement temperature, and the flow behavior index did not show constant relationship. The consistency index and yield stress of the gelatinized starch on addition of phosphate decreased as the flow behavior index increased. The values of activation energy at initial and equilibrium were 1.52 kcal/g.mole and 127 kcal/g.mole, respectively.

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Development of Wheel Loader V-Pattern Operator Model for Virtual Evaluation of Working Performance (휠로더 가상 성능평가를 위한 V상차 작업 운전자 모델)

  • Oh, Kwangseok;Kim, Hakgu;Ko, Kyungeun;Kim, Panyoung;Yi, Kyongsu
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.38 no.11
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    • pp.1201-1206
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    • 2014
  • This paper presents the development of an event-based operator model of a wheel loader for virtual V-pattern working. The objective of this study is to analyze the performance and dynamic behavior of the wheel loader for a typical V-pattern. The proposed typical V-pattern working is divided into four stages. The developed operator model is based on eight events, and the operator's inputs are occurred sequentially by event. A 3D dynamic simulation model of the wheel loader is developed and used to analyze the dynamic behavior during working, and the simulation results are compared with the experimental data of V-pattern working. The proposed 3D dynamic simulation model and operator model are constructed using MATLAB/Simulink. The proposed operator model for V-pattern working is expected to enable evaluation of the working performance and dynamic behavior of the wheel loader.

Comparison of GPU-Based Numerous Particles Simulation and Experiment (GPU 기반 대량입자 거동 시뮬레이션과 실험비교)

  • Park, Sang Wook;Jun, Chul Woong;Sohn, Jeong Hyun;Lee, Jae Wook
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.38 no.7
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    • pp.751-756
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    • 2014
  • The dynamic behavior of numerous grains interacting with each other can be easily observed. In this study, this dynamic behavior was analyzed based on the contact between numerous grains. The discrete element method was used for analyzing the dynamic behavior of each particle and the neighboring-cell algorithm was employed for detecting their contact. The Hertzian and tangential sliding friction contact models were used for calculating the contact force acting between the particles. A GPU-based parallel program was developed for conducting the computer simulation and calculating the numerous contacts. The dam break experiment was performed to verify the simulation results. The reliability of the program was verified by comparing the results of the simulation with those of the experiment.

Pervaporation of Water/ethanol Mixtures Using PVA Membranes Crosslinked with Poly (styrene-maleic anhydride): Study on the Separation Behavior (Poly (styrene-maleic anhydride)로 가교된 Poly (vinyl alcohol)막을 이용한 물/에탄올 수용액의 투과증발: 분리거동에 관한 연구)

  • Kim, Sang-Gyun;Lim, Gyun-Taek;Park, Sang-Wook
    • Applied Chemistry for Engineering
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    • v.9 no.4
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    • pp.469-474
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    • 1998
  • Poly (vinyl alcohol) (PVA) membranes crosslinked with poly (styrene-co-maleic anhydride) (PSMAn) have been prepared by the solution method. To investigate the separation behavior of the crosslinked PVA/PSMAn membranes in the pervaporation process, the selective sorption experiment and swelling measurements of the membranes in ethanol-water mixtures of 30~90 wt % ethanol contents were conducted with equipment that was able to measure the concentration and amount of the liquid absorbed in the membranes. The membranes prepared in this study exhibited good selectivity toward water component in sorption and permeation. Also, in the feed containing ethanol more than 50 wt %, the permeation selectivity of the membrane showed better correlation with the sorption selectivity than that with the swelling ratio changing toward the crosslinking content. This behavior was consistence with a solution-diffusion model correlating permeation and sorption selectivity, and led to the conclusion that the permeation selectivity was determined by sorption step rather than by diffusion step in the membrane.

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Fracture Behavior of Graphite Material at Elevated Temperatures Considering Oxidation Condition (산화환경을 고려한 흑연 내열재의 고온파단특성)

  • Choi, Hoon Seok;Kim, Jae Hoon;Oh, Kawng Keun
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.39 no.11
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    • pp.1091-1097
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    • 2015
  • Graphite material has been widely used for making the rocket nozzle throat because of its excellent thermal properties. However, when compared with typical structural materials, graphite is relatively weak with respect to both strength and toughness, owing to its quasi-brittle behavior, and gets oxidized at $450^{\circ}C$. Therefore, it is important to evaluate the thermal and mechanical properties of this material for using it in structural applications. This study presents an experimental method to investigate the fracture behavior of ATJ graphite at elevated temperatures. In particular, the effects of major parameters such as temperature, loading, and oxidation conditions on strength and fracture characteristics were investigated. Uniaxial compression and tension tests were conducted in accordance with the ASTM standard at room temperature, $500^{\circ}C$, and $1,000^{\circ}C$. Fractography analysis of the fractured specimens was carried out using an SEM.

Hydrogen Embrittlement Behavior of High Mn TRIP/TWIP Steels (고 Mn계 TRIP/TWIP 강의 수소취성 거동)

  • Jung, Jong-Ku;Lee, Oh-Yeon;Park, Young-Koo;Kim, Dong-Eun;Jin, Kwang-Geun
    • Korean Journal of Materials Research
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    • v.18 no.7
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    • pp.394-399
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    • 2008
  • The hydrogen embrittlement susceptibility of high strength TRIP/TWIP steels with the tensile strength of 600Mpa to 900Mpa grade was investigated using cathodically hydrogen charged specimens. TWIP steels with full austenite structure show a lower hydrogen content than do TRIP steels. The uniform distribution of strong traps throughout the matrix in the form of austenite is considered beneficial to reduce the hydrogen embrittlement susceptibility of TWIP steels. Moreover, an austenite structure with very fine deformation twins formed during straining could also improve the ductility and reduce notch sensitivity. In Ubend and deep drawing cup tests, TWIP steels show a good resistance to hydrogen embrittlement compared with TRIP steels.

Electrochemical Properties of Polyaniline Cathode for Lithium Secondary Batteries (리튬 2차 전지용 Polyaniline cathode의 전기화학적 특성)

  • Kim, H.C.;Kim, J.U.;Gu, H.B.;Moon, S.I.
    • Proceedings of the KIEE Conference
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    • 1996.07c
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    • pp.1685-1687
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    • 1996
  • Recently, conducting polymer has been much attracted as novel materials because of its electronic behavior and functional application by doping process. In this paper, we electrochemically synthesized polyaniline films under potential sweep conditions, which exhibit high electric conductivity about 200 S/cm. Specific energy of 600 Wh/kg and Ah efficiency 98% were achieved during the charge/discharge cycling using liquid electrolyte system. On the other hand, consequences of the cycling were 260 Wh/kg and 95% Ah efficiency using polyethylene oxide(PEO) based solid-state electrolyte system.

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A Study on the Design of Simple Auto-tunig PID Controller (단순한 자동동조 PID제어기의 설계에 관한 연구)

  • Seul, Nam-O;Shin, Man-Sic;Lee, Chang-Goo
    • Proceedings of the KIEE Conference
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    • 1995.07b
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    • pp.795-797
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    • 1995
  • In this paper, we present a simple auto-tuning PID controller using genetic algorithms. The basic idea of the scheme is to parameterize a Ziegler-Nichols-like tuning formula by a single parameter ${\alpha}$, then to use GA to select optimal tuning parameter. Also, simple rule mechanisms make the controller adapt against large variations in parametric and dynamics uncertainties in the plant. These scheme lead to improved performance of the transient and steady state behavior of the closed loop system, including processes with long delay-time and nonminimum phase systems.

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Study on the Damage Behavior of 304 Stainless Steel for Gas Boiler with Specific Resistance (비저항에 따른 가스보일러용 304스테인리스강재의 손상거동에 관한 연구)

  • Yun, Byoung-Du;Lim, Uh-Joh;Jeong, Ki-Cheol
    • Journal of the Korean Institute of Gas
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    • v.9 no.4 s.29
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    • pp.6-10
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    • 2005
  • This paper was studied on the damage behavior of stainless steel (STS 304) for gas boiler with specific resistance. The electrochemical polarization test of STS304 for gas boiler was carried out. And the anodic polarization and damage aspect, such as pitting corrosion, was considered. With being low specific resistance, the passive current density of STS 304 increases, passive region and pitting potential is low. Also, the patting aspect of STS304 In specific resistance $74{\Omega}{\cdot}m$ water little appears, the pitting number increases and the damage behavior, such as pitting aspect, gradually grow bigger with being low specific resistance.

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The Phase Behavior of Nonionic Surfactants having Sucrose as Hydrophilic Group(II) - The Phase Behavior of Sucrose Monopalmitate/Alkanol/Water System - (당류를 친수기로 한 비이온성 계면활성제계의 상거동(제2보) - 슈크로오스 팔미테이트/알칸올/물 계에서의 상거동 -)

  • Lee, Hyang-Woo;Lee, Jin-Hee;Nam, Ki-Dae
    • Applied Chemistry for Engineering
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    • v.8 no.2
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    • pp.246-251
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    • 1997
  • The phase behavior of sucrose monopalmitate/alkanol/water ternary system was investigated. According to compositions of three components ranging from micellar(or inverse micellar) solution up to various lyotropic liquid crystalline(LC) phase, each texture of the separated phases was identified by crossed polarizers equipped with a camera whose stage was connected to a thermostatic circulator. As the carbon atom number in alkanol of the polar oily substance increases, patterns of the various LC phases were also observed hexanol

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