• Title/Summary/Keyword: 시간-온도 파라미터

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Aging Degradation Assessment of Materials by Ultrasonic Characterization (초음파 특성을 이용한 경년열화 평가)

  • Park, Un-Su;Park, Ik-Keun;Kim, Duck-Hee;Ahn, Hyung-Keun
    • Journal of the Korean Society for Nondestructive Testing
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    • v.22 no.2
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    • pp.149-154
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    • 2002
  • An attempt was made to evaluate the changes of microstructures and mechanical properties with increasing aging time in 2.25Cr-1Mo steel. In this study, it was verified the feasibility of the evaluation for degraded 2.25Cr-1Mo steel by isothermal heat treatment at $630^{\circ}C$ up to 1,000 hours using surface SH wave and investigated the change of attenuation coefficient and propagation time. Attenuation coefficient had a tendency to increase according to degradation and propagation time drastically in the beginning of deterioration. A good correlation between ultrasonic attenuation coefficient and hardness was found, which made sure that attenuation coefficient is an potential parameter for evaluation of aging degradation. In addition, it has verified experimentally the frequency dependence of ultrasonic group velocity and attenuation coefficient using wavelet transform.

Equilibrium, Kinetic and Thermodynamic Parameter Studies on Adsorption of Allura Red from Aqueous Solution by Granular Activated Carbon (입상활성탄에 의한 수용액으로부터 오로라 레드의 흡착에 대한 평형, 동력학 및 열역학 파라미터에 관한 연구)

  • Lee, Jong-Jib
    • Applied Chemistry for Engineering
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    • v.25 no.4
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    • pp.430-436
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    • 2014
  • Allura Red (AR) is a water-soluble harmful tar-based food colorant (FD & C Red 40). Batch adsorption studies were performed for the removal of AR using bituminous coal based granular activated carbon as adsorbent by varying the operation parameters such as adsorbent dosage, initial concentration, contact time and temperature. Experimental equilibrium adsorption data were analyzed by Langmuir, Freundlich and Temkin isotherms. The equilibrium process was described well by Freundlich isotherm. From determined separation factor ($R_L$), adsorption of AR by granular activated carbon could be employed as effective treatment method. Temkin parameter, B was determined to 1.62~3.288 J/mol indicating a physical adsorption process. By estimation of adsorption rate experimental data, the value of intraparticle diffusion rate constant ($k_m$) increased with the increasing adsorption temperature. The adsorption process were found to confirm to the pseudo second order model with good correlation. Thermodynamic parameters like change of free energy, enthalpy, and entropy were also calculated to predict the nature adsorption in the temperature range of 298~318 K. The negative Gibbs free energy change (${\Delta}G$ = -2.16~-6.55 kJ/mol) and the positive enthalpy change (${\Delta}H$ = + 23.29 kJ/mol) indicated the spontaneous and endothermic nature of the adsorption process, respectively.

Development of forest carbon optimization program using simulated annealing heuristic algorithm (Simulated Annealing 휴리스틱 기법을 이용한 임분탄소 최적화 프로그램의 개발)

  • Jeon, Eo-Jin;Kim, Young-Hwan;Park, Ji-Hoon;Kim, Man-Pil
    • Journal of the Korea Society of Computer and Information
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    • v.18 no.12
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    • pp.197-205
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    • 2013
  • In this study, we developed a program of optimizing stand-level carbon stock using a stand-level yield model and the Simulated Annealing (SA) heuristic method to derive a optimized forest treatment solution. The SA is one of the heuristic algorithms that can provide a desirable management solution when dealing with various management purposes. The SA heuristic algorithm applied 'thermal equilibrium test', a thresholds approach to solve the phenomenon that does not find an optimum solution and stays at a local optimum value during the process. We conducted a sensitivity test for the temperature reduction rate, the major parameter of the thermal equilibrium test, to analyze its influence on the objective function value and the total iteration of the optimization process. Using the developed program, three scenarios were compared: a common treatment in forestry (baseline), the optimized solution of maximizing the amount of harvest(alternative 1), and the optimized solution of maximizing the amount of carbon stocks(alternative 2). As the results, we found that the alternative 1 showed provide acceptable solutions for the objectives. From the sensitivity test, we found that the objective function value and the total iteration of the process can be significantly influenced by the temperature reduction rate. The developed program will be practically used for optimizing stand-level carbon stock and developing optimized treatment solutions.

The analysis on properties of IR emitter unit device fabricated by using MEMS technology for Infrared Scene Projector (MEMS 기술을 이용하여 제작한 적외선 영상 투사용 에미터 단위 소자의 특성 분석)

  • Park, Ki Won;Shin, Young Bong;Kang, In-Ku;Lee, Hee Chul
    • Journal of the Institute of Electronics and Information Engineers
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    • v.54 no.3
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    • pp.31-36
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    • 2017
  • In this paper, designed infrared (IR) emitter device for infrared scene projector (IRSP) which is used for evaluating the performance of IR sensor systems was simulated by using finite element analysis (FEA) tool and fabricated by using MEMS (Micro Electro-Mechanical System) technology. The performance of the fabricated IR emitter unit device was characterized in the vacuum chamber by using IR image microscope for MWIR($3{\sim}5{\mu}m$), which showed 423K apparent temperature (Tapp) and 22msec time constant (${\tau}$).

Equilibrium, Kinetic and Thermodynamic Parameter Studies on Adsorption of Acid Black 1 Using Coconut Shell-Based Granular Activated Carbon (야자각계 입상 활성탄의 Acid Black 1 염료 흡착에 대한 평형, 동역학 및 열역학 파라미터의 연구)

  • Lee, Dong-Chang;Lee, Jong-Jib
    • Applied Chemistry for Engineering
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    • v.27 no.6
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    • pp.590-598
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    • 2016
  • In this study, the adsorption behavior from aqueous solution as well as kinetic and thermodynamic parameters of Acid Black 1 were investigated through batch reaction using coconut shell based granular steam activated carbon. The effects of various adsorption parameters such as pH, initial concentration, contact time, temperature were studied. To confirm the effect of pH, pHpzc measurements were analyzed followed by measuring removal efficiencies of Acid Black 1 at the pH range from 3 to 11. Experimental equilibrium adsorption data were fitted using Langmuir, Freundlich, Temkin and Dubinin-Radushkevich adsorption isotherm. The conformity of adsorption reaction for pseudo first and second order model were evaluated through kinetic analysis. Values of enthalpy change and activation energy were also investigated through thermodynamic analysis and it was confirmed that the adsorption process was endothermic. The spontaneity of adsorption process was evaluated using the values of entropy and Gibbs free energy changes.

Creep-Life Prediction and Standard Error Analysis of Type 316LN Stainless Steel (Type 316LN 스테인리스 강의 크리프 수명 예측과 표준오차 분석)

  • Yun S.N.;Kim W.G.;Liu W.S.;Yi W.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2005.06a
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    • pp.1406-1411
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    • 2005
  • The creep rupture data for type 316LN stainless steels were collected through literature survey or experimental data produced in KAERI. Using these data, polynomial equations for predicting creep life were obtained by Larson-Miller (L-M), Orr-Sherby-Dorn (O-S-D) and Manson-Haferd (M-H) etc. time-temperature parametric (TTP) methods. Standard error of estimate (SEE) values for the each parameter was obtained with different temperatures through the statistical process of the creep data. The results of L-M, O-S-D and M-H methods showed good creep-life prediction, but M-H method showed better agreement than L-M and O-S-D methods. Especially, it was found that SEE values of M-H method at $700^{\circ}C$ were lower than that of L-M and O-S-D methods.

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A Study on Fault Detection using Fuzzy Trend Monitoring Technique of UAV Turbofan Engine (퍼지 경향 감시 기법을 이용한 무인기용 터보팬 엔진의 손상 탐지에 관한 연구)

  • Kong, C.D.;Kho, S.H.;Ki, J.Y.;Kho, H.Y.;Oh, S.H.;Kim, J.H.
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2007.11a
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    • pp.345-349
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    • 2007
  • In this study a fuzzy trend monitoring method for detecting the engine mechanical faults was proposed through analyzing performance trends of measurement data. The trend monitoring is an engine conditioning method which can find engine faults by monitoring important measuring parameters such as fuel flow, exhaust gas temperatures, rotational speeds, vibration. etc. Using engine condition data set as a input which generated by linear regression analysis of real engine instrument data, an application of fuzzy logic in diagnostics estimate a cause of fault in each components.

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A Study on Fuzzy Trend Monitoring Method for Fault Detection of Gas Turbine Engine (가스터빈 엔진의 손상 진단을 위한 퍼지 경향감시 방법에 관한 연구)

  • Kong, Chang-Duk;Kho, Seong-Hee;Ki, Ja-Young;Oh, Sung-Hwan;Kim, Ji-Hyun;Ko, Han-Young
    • Journal of the Korean Society of Propulsion Engineers
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    • v.12 no.6
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    • pp.1-6
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    • 2008
  • This work proposes a fuzzy trend monitoring method for the fault detection of a gas turbine engine through analyzing measured performance data trend. The proposed trend monitoring technique can diagnose the engine status by monitoring major engine measured parameters such as fuel flow rate, exhaust gas temperature, rotor rotational speed and vibration, and then analyzing their time deppendent changes. In order to perform this, firstly the measured engine performance data variation is formulated using Linear Regression, and then faults are isolated and identified using fuzzy logic.

Creep Life Prediction and Error Analysis for Type 316LN Stainless Steel (Type 316LN 스테인리스강의 크리프 수명예측과 오차분석)

  • Yi W.;Yin S.N.;Kim W.G.;Ryu W.S.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2006.05a
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    • pp.109-110
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    • 2006
  • Various parametric methods, Larson-Miller (L-M), Orr-Sherby-Dorn (O-S-D), Manson-Haferd (M-H) parameters, and minimum commitment method (MCM), were used to predict longer rupture time from short-term creep data. A number of the creep data were collected through literature surveys and experimental data produced in KAERI for predicting the creep type of type 316LN SS. Polynomial equations for predicting the creep life were obtained by the time-temperature parameters (TTP) and the MCM. standard error (SE) and standard error or mean (SEM) values were compared for the each method with temperatures. The TTP methods were good in the creep-life prediction, but the MCM was much superior to the TTP ones at $700^{\circ}C\;and\;750^{\circ}C$. The MCM was found to be lower in the SE values compared to the TTP methods

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A Study on Estimation of Cooling Load Using Forecasted Weather Data (집단 건물 면적을 이용한 시간별 냉방부하 파라미터 설정 및 예측에 관한 연구)

  • Han, Kyu-Hyun;Yoo, Seong-Yeon;Lee, Je-Myo;Song, Yang-Sup
    • Proceedings of the SAREK Conference
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    • 2008.11a
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    • pp.440-445
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    • 2008
  • In this paper, new methodology is proposed to estimate the cooling load using areas of building group and predicted weather data. Only three parameters such as maximum, minimum temperature and building area are necessary to obtain hourly distribution of cooling load for the next day. The maximum and minimum temperature that are used for input parameters can be obtained from forecasted weather data. The areas of building group are used for setting several parameters that are used for estimate cooling loads. Benchmarking building(research building) is selected to validate the performance of the proposed method, and the estimated cooling loads in hourly bases are calculated and compared with the measured data for benchmarking building. The estimated results show fairly good agreement with the measured data for benchmarking building.

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