• Title/Summary/Keyword: Reference gas

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Robust Air-to-fuel Ratio Control Algorithm of Passenger Car Diesel Engines Using Quantitative Feedback Theory (QFT 기법을 이용한 승용디젤엔진 공연비 제어 알고리즘 설계 연구)

  • Park, Inseok;Hong, Seungwoo;Shin, Jaewook;Sunwoo, Myoungho
    • Transactions of the Korean Society of Automotive Engineers
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    • v.21 no.3
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    • pp.88-97
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    • 2013
  • This paper presents a robust air-to-fuel ratio (AFR) control algorithm for managing exhaust gas recirculation (EGR) systems. In order to handle production tolerance, deterioration and parameter-varying characteristics of the EGR system, quantitative feedback theory (QFT) is applied for designing the robust AFR control algorithm. A plant model of EGR system is approximated by the first order transfer function plus time-delay (FOPTD) model. EGR valve position and AFR of exhaust gas are used as input/output variables of the plant model. Through engine experiments, parameter uncertainty of the plant model is identified in a fixed engine operating point. Requirement specifications of robust stability and reference tracking performance are defined and these are fulfilled by the following steps: during loop shaping process, a PID controller is designed by using a nominal loop transmission function represented on Nichols chart. Then, the frequency response of closed-loop transfer function is used for designing a prefilter. It is validated that the proposed QFT-based AFR control algorithm successfully satisfy the requirements through experiments of various engine operating points.

Application of the WSGGM for arbitrary gas mixtures of water vapor and carbon dioxide (임의 성분비로 구성된 수증기-이산화탄소 혼합가스에 대한 회색가스가중합법의 적용 연구)

  • Park, Won-Hee;Kim, Tae-Kuk
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.31 no.6
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    • pp.88-95
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    • 2003
  • The weighted sum of gray gas model(WSGGM) is applied to arbitrary mixtures of CO$_2$ and H$_2$0 gases. To evaluate this model, the spectral and total intensities are obtained for two different problem types. One has uniform, parabolic and boundary layer type temperature profiles with uniform partial pressure, and the other has nonuniform partial pressure and temperature profile. The results obtained from the two different problem types show fairly good agreements with the results obtained by the statistical narrow band model(SNB model) which is regarded as the reference solutions. The WSGGM and its data base provided by this study can be used for analysis of radiative transfer by combustion gases with different thermal loadings and chemical compositions.

Improving Compression and Throat Ratios of Combustion Chamber for Reduction of Exhaust Emissions for a Swirl Chamber Type Diesel Engine (와류실식 디젤기관의 배기배출물 저감을 위한 연소실의 압축비 및 분구면적비 개선)

  • Lee, Chang-Kyu;Huh, Yun-Kun;Seo, Sin-Won
    • Korean Journal of Agricultural Science
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    • v.37 no.3
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    • pp.501-508
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    • 2010
  • A swirl chamber type diesel engine attachable to 18 kW agricultural tractors was improved to reduce exhaust emissions. Compression ratio and throat area ratio of the combustion chamber were varied to determine optimum combustion conditions. Tests were composed of full load and 8-mode emission tests. Compression ratio was fixed as 21, but the swirl chamber volume was increased by 3.8%. Output power, torque, specific fuel consumption, exhaust gas temperature, and smoke level were not considerably different for compression ratios of 21.5 (reference condition) and 21 (test condition), while NOx, HC, CO and PM levels for the compression ratio of 21 were decreased by 11%, 46%, 28%, 11%, respectively, from those for the compression ratio of 21.5. The tests were also conducted with a compression ratio of 22 and 4.3% increased chamber volume. Output power, torque, exhaust gas temperature and smoke level were greater, while specific fuel consumption was less for the compression ratio of 22 than those for the compression ratio of 21.5. Increase of compression ratio decreased HC and CO levels by 24%, 39%, but increased NOx and PM levels by 24%, 39%. Based on these results, a compression ratio of 21 was selected as an optimum value. Then, full load tests with the selected compression ratio of 21 were carried out for different throat ratios of 1.0%, 1.1%, 1.2%. Output power and torque were greatest and smoke was lowest when throat area ratio was 1.1%, which satisfied the target values of specific fuel consumption (less than 272 g/$kW{\cdot}h$) and exhaust gas temperature (less than $550^{\circ}C$). Therefore, a throat area ratio of 1.1% was selected as an optimum value.

A Study on the Metal Mesh for CuNx-Cu-CuNx Multi-layer Touch Electrode by Reactive Magnetron Sputtering (Reactive Magnetron Sputtering 적용 CuNx-Cu-CuNx 적층형 Metal Mesh 터치센서 전극 특성 연구)

  • Kim, Hyun-Seok;Yang, Seong-Ju;Noh, Kyeong-Jae;Lee, Seong-Eui
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.29 no.7
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    • pp.414-423
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    • 2016
  • In the present study, the $CuN_x-Cu-CuN_x$ layer the partial pressure ratio Cu metal of Ar and $N_2$ gas using a DC magnetron sputtering device, was generated by the In-situ method. $CuN_x$ layer was able to obtain a surface reflectance reduction effect from the advantages of the process and the external light. $CuN_x$ layer is gas partial pressure, DC the Power, the deposition time variable transmittance in response to the thickness and partial pressure ratio, the reflectance was measured. $Ar:N_2$ gas ratio 10:10(sccm), DC power 0.35 A, was derived Deposition time 90 sec optimum conditions. Thus, according to the optimal thickness and the composition ratio was derived surface reflectance of 20.75%. In addition, to derive the value of ${\Delta}$ Ra surface roughness of 0.467. It was derived $CuN_x$ band-gap energy of about 2.2 eV. Thus, to ensure a thickness and process conditions can be absorbed to maximize the light in a wavelength band in the visible light region. As a result, the implementation of the $12k{\Omega}$ base line resistance of using the Cu metal. This is, 5 inch Metal mesh TSP(L/S: $4/270{\mu}m$) is in the range of the reference operation.

Forensic Engineering Study on Assessment of Damage to Pressure Vessel Because of CNG Vehicle Explosion (CNG 차량 폭발의 용기 손상 평가에 관한 법공학적 연구)

  • Kim, Eui-Soo
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.35 no.4
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    • pp.439-445
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    • 2011
  • Forensic Engineering is the art and science of professionals qualified to serve as engineering experts in courts of law or in arbitration proceedings. Buses using compressed natural gas (CNG) trend to be extended in use internationally as optimal counterplan for reducing discharge gas of light oil due to high concern about environment. However, CNG buses have to be equipped with composite pressure vessels (CPVs); since the CPVs contain compressed natural gas, the risks in the case of accident is very high. Hence, the investigation of such accidents is usually associated with engineering analysis. Among the possible reasons for such CNG explosion accidents is vehicle fire and vessel fracture. By conducting formal inspection and engineering tests, in this study, the cause of vessel explosion is investigated by analyzing the failure mechanism by fractography and by comparing the material properties of a reference part with those of a problem part by adopting instrumented indentation technique.

A Study on a Precision Temperature Control of Oil Coolers with Hot-gas Bypass Manner for Machine Tools Based on Fuzzy Control (퍼지제어를 이용한 공작 기계용 오일 쿨러의 핫가스 바이패스방식 정밀 온도 제어에 관한 연구)

  • Lee, Sang-Yun
    • Journal of the Institute of Convergence Signal Processing
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    • v.14 no.3
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    • pp.205-211
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    • 2013
  • Recently, the needs of system performances such as working speed and processing accuracy in machine tools have been increased. Especially, the working speed increment generates harmful heat at both moving part of the machine tools and handicrafts. The heat is a main drawback to progress accuracy of the processing. Hence, a oil cooler to control temperature is inevitable for the machine tools. In general, two representative control schemes, hot-gas bypass and variable speed control of a compressor, have been adopted in the oil cooler system. This paper deals with design and implementation method of fuzzy controller for obtaining precise temperature characteristic of HB oil cooler system in machine tools. The opening angle of an electronic expansion valve are controlled to keep reference value and room temperature of temperature at oil outlet. Especially, the fuzzy controller is added to suppress temperature fluctuation under abrupt disturbances. Through some experiments, the suggested method can control the target temperature within steady state error of ${\pm}0.22^{\circ}C$.

Life Cycle Assessment of Greenhouse Gas Emissions from Livestock and Food Wastes Co-digestive Biogas Production System (전과정평가 방법을 이용한 가축분뇨/음식폐기물 통합 소화형 바이오가스 시설의 온실가스 배출량 평가)

  • Nam, Jae-Jak;Yoon, Young-Man;Lee, Young-Haeng;So, Kyu-Ho;Kim, Chang-Hyun
    • Korean Journal of Environmental Agriculture
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    • v.27 no.4
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    • pp.406-412
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    • 2008
  • Biogas plant with anaerobic digestion is receiving high attention as a facility for both livestock waste treatment and electric power generation. Objective of this study was to perform life cycle assessment (LCA) of a biogas plant which incorporates swine and food waste (7:3) as source materials for biogas production. In addition, the biogas production process was compared with the prevalent composting method as a reference in the aspects of green house gas (GHG) reduction potential and environmental impact. The biogas method was capable of reducing 52 kg $CO_2$ eq. emission per ton of swine/food waste, but the composting process was estimated to emit 268 kg $CO_2$ eq. into air. The biogas method was evaluated as more beneficial to the environment by mitigating the impact on abiotic depletion potential (ADP), global warming potential (GWP), ozone depletion potential (ODP), eutrophication potential (EP), and photochemical ozone creation potential (POCP), but not to acidification potential (AP).

Fermentation Properties of Irradiated Kochujang (방사선 조사 고추장의 발효 특성)

  • Kim, Moon-Sook;Oh, Jin-A;Kim, In-Won;Shin, Dong-Hwa;Han, Min-Su
    • Korean Journal of Food Science and Technology
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    • v.30 no.4
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    • pp.934-940
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    • 1998
  • Kochujang, fermented hot pepper soybean paste, was prepared by traditional method, and irradiated with gamma ray of $^{60}Co{\;}up{\;}to{\;}15{\pm}1.5{\;}kGy$ for confirming main factor of kochujang fermentation. Nonirradiated (control) and irradiated samples kochujang were fermented at $25^{\circ}C$ and analyzed biochemical properties including enzyme activities and viable cell count during fermentation for 60 days. The total viable count in irradiated kochujang decreased to $10^4{\;}CFU/g$ which was $10^8{\;}CFU/g$ in the control. Because of a little changing enzyme activities of ${\alpha}{\cdot}{\beta}{\;}amylase$ and acid neutral protease by irradiation at the above level, amino type nitrogen which is the main quality reference of kochujang was comparable to the control. By irradiation, gas production was completely stopped which is one of biggest problems during distribution of kochujang. Total volume of gas produced at $25^{\circ}C$ from the control kochujang was 453 mL/100 g which was composed of over 90% of $CO_2$. The odor of irradiated kochujang was inferior to the control which seemed to be related to reduced microbial populations.

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Performance Evaluation on Blast-resistant of Gastight Door using Numerical Simulation (수치해석을 활용한 가스차단문의 폭발압력저항 성능평가)

  • Shin, Baegeun;Kim, Jiyu;Kim, Euisoo
    • Journal of the Korean Institute of Gas
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    • v.26 no.1
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    • pp.27-33
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    • 2022
  • As the scale of explosions diversifies along with the expansion of gas handling and storage facilities, studies on explosion-proof facilities in preparation for accidents is being actively conducted. The gastight door blocks the expansion pressure caused by blast waves or internal fires, and at the same time protects the personnel and equipment inside. For gastight doors, the regulations related to explosion-proof design are not clearly presented, and studies on the explosion pressure resistance performance evaluation of the facility are insufficient. In this study, the gastight door was modeled in a 3D shape with reference to the regulation ASTM regarding the gastight door standard. Afterwards, evaluation for blast-resistant performance of gastight door using Numerical simulation was evaluated by using ANSYS Explicit Dynamics to compare the deformation.

Heat transfer characteristics of an internal cooling channel with pin-fins and ribbed endwalls in gas turbine blade

  • Vu T.A. Co;Hung C. Hoang;Duy C.K. Do;Son H. Truong;Diem G. Pham;Nhung T.T. Le;Truong C. Dinh;Linh T. Nha
    • Advances in aircraft and spacecraft science
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    • v.11 no.2
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    • pp.153-175
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    • 2024
  • In jet engines, turbine blade cooling has an extremely important role. The pin-fin array, which is situated close to the trailing edge of the blade, aids in internal cooling of the gas turbine blades and preserves the structural integrity of the blade. Previous studies often focused on pin-fin configurations, but the current research focuses on improving the geometry at the endwalls to reduce wake vortices behind the pin-fins and enhance heat transfer at the endwalls location. Using the k-ω turbulence model, a numerical study was conducted on a ribbed shape situated on the walls between pin-fin arrays, spanning a Reynolds number range of 7400 to 36000, in order to determine the heat transport characteristics. The heat transfer efficiency coefficient and Nusselt number increase dramatically with the revised wall configuration, according to the numerical data. The channel's heat transfer efficiency is increased by enlarging the heat transfer areas near the pin-fins and by the interaction of the flow with the endwalls. The addition of ribs causes the Nusselt number of the new model to climb from 78% to 96% at the previously given Reynolds numbers, and the heat transfer efficiency index to rise from 60% to 73%. The height (Hr), position (Lr), forward width (Wf), and backward width (Wb) of the ribs are among the geometric elements that were looked at in order to determine how they affected the performance of heat transmission. In comparison to the reference design, the parametric study results demonstrate that the best forward width (Wf/R=18.75%) and backward width (Wb/R=31.25%) increase the heat transfer efficiency index by 0.4% and 1.3%, respectively.