• 한국자동차공학회논문집
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• 제5권2호
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• pp.173-182
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• 1997

The instantaneous flame temperature and soot formation and oxidation in a D. I. diesel engine are measured by using a two-color method. The proposed method based on the continuous spectral radiation from the soot particles in flames is applicable to industrial diesel engines without major modifications of their main characteristics. Measurements are performed at one location inside the combustion chamber of a D.I. diesel engine. Effects of different engine speeds and loads on flame temperature and KL factor which is an index of soot concentrations were examined. A little temperature change were observed with increasing engine speed, while increased with loads. The higher the flame temperature is, the lower the KL factor is.

• 대한기계학회논문집B
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• 제21권11호
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• pp.1475-1484
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• 1997

A new empirical formula for instantaneous heat transfer coefficients was determined. The determination of this formula is in need for prediction of instantaneous value of heat transfer coefficients to analyze in more detail the time variation of heat transfer rate from gas to wall in combustion chamber of a spark ignition engine. As the result, following formula was determined. h=687 $p^{0.75}$ $U^{0.75}$ $D^{0.25}$ - $T^{-0.465}$ U(.theta.)=O.494 $V_{p}$ +0.73*10$^{6}$ (1.35 p dV/d.theta.+V dp/d.theta.) Using this empirical formula, the instantaneous heat transfer coefficients of gas in the combustion chamber of spark ignition engine was predicted and compared with experimental values.

• 한국태양에너지학회 논문집
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• 제36권2호
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• pp.73-78
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• 2016

This study investigates the main factors of fire prevention, such as spontaneous ignition and flash point, while using Diehylene Glycol (DEG) as the antifreeze for automobile and industrial machines. Our results show the flash point of $142^{\circ}C$ and the minimum ignition temperature of $388^{\circ}C$ in the range of $130{\mu}{\ell}{\sim}150{\mu}{\ell}$. By increasing temperature to ignite in 1 second, an instantaneous ignition temperature of the sample is $569^{\circ}C$ in the sample amount of $140{\mu}{\ell}$.

• 대한기계학회논문집
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• 제1권4호
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• pp.171-181
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• 1977

This paper is aiming at calculating NOx concentration, which is one of the harmhul components of emission from the gasoline engine, formed in the combustor through the presess of combustion. Instantaneous temperature and concentration of each components for each division can be determined by the solution of simulatneous equation of reaction equation and equation of energy conservation, inputting the estimated temperature with a considerably wide rage of temperature. After determining instantaneous temperature and instantanous concentration of each components, the nonequilibrium calculation is performed based on the reaction kinetics in order to determine NOx concentration. To summarize the result abtained from the above method ;through the passage of NO concentration, NO concentration is the highest in the first division and it is gradually decreasing through the following divisions In the final division, NO concentation is the lowest.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2002년도 학술대회지
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• pp.513-516
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• 2002

The flow structure and heat transfer characteristics of a turbulent buoyant jet were investigated experimentally. The instantaneous temperature and velocity fields in the near field were measured using a two-frame PIV and PLIF techniques. A thin light sheet illuminated a two-dimensional cross section of the buoyant jet in which Rhodamine B was added as a fluorescent dye. The intensity variations of LIF signal from Rhodamine B molecules scattered by the laser light were captured by a CCD camera after passing an optical filter. By ensemble averaging the instantaneous temperature and velocity fields, the mean temperature and velocity fields as well as the spatial distributions of turbulent statistics were obtained. The results show the flow structure and convective heat transfer of the developing shear layer in the near field.

• Smart Structures and Systems
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• 제22권1호
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• pp.1-11
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• 2018

This study presents early crack detection of steel fiber-reinforced concrete (SFRC) under varying temperature and humidity conditions using an instantaneous electrical impedance acquisition system. SFRC has the self-sensing capability of electrical impedance without sensor installation thanks to the conductivity of embedded steel fibers, making it possible to effectively monitor cracks initiated in SFRC. However, the electrical impedance is often sensitively changed by environmental effects such as temperature and humidity variations. Thus, the extraction of only crack-induced feature from the measured impedance responses is a crucial issue for the purpose of structural health monitoring. In this study, the instantaneous electrical impedance acquisition system incorporated with SFRC is developed. Then, temperature, humidity and crack initiation effects on the impedance responses are experimentally investigated. Based on the impedance signal pattern observation, it is turned out that the temperature effect is more predominant than the crack initiation and humidity effects. Various crack steps are generated through bending tests, and the corresponding impedance damage indices are extracted by compensating the dominant temperature effect. The test results reveal that propagated cracks as well as early cracks are successfully detected under temperature and humidity variations.

• Current Optics and Photonics
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• 제4권4호
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• pp.361-367
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• 2020

An approach based on an integrated photonic Ti:LiNbO₃ Y branch has been proposed, designed, and analyzed for the microwave instantaneous frequency measurement (IFM). By designing the Y branch with length L = 6545 ㎛ and refractive index N_TE - N_TM = 0.0764, a complementary optical filter with free spectral range (FSR) of 600 GHz is constituted, which results in a maximum measureable frequency of 300 GHz being obtained. Theoretical analysis on the temperature stability of the Ti:LiNbO₃ Y branch shows that the FSR variation of the complementary filter is 0.3% for the temperature change of 100 K, which indicates that the IFM approach will have a better stability. All these results demonstrate that the proposed IFM approach has potential capability to be used for the increasingly higher microwave IFM with better stability.

• 한국광학회지
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• 제7권4호
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• pp.348-356
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• 1996

기체의 순간 온도를 측정할 수 있는 펄스 레이저를 사용한 이동형 CARS 분광기를 제작하였다. 이 분광기의 측정 프로그램은 측정한 스펙트럼으로 부터 온도를 얻기 위하여 8가지의 빠른 온도 계산법과 최소제곱법을 포함하고 있다. 빠른 온도 계산법 중 두 가지는 최소제곱법 보다 계산 시간은 훨씬 덜 걸리면서 온도의 분산이 작은 측정 결과를 준다. CARS 온도의 정밀 정확도는 복사온도계를 기준으로 흑연관 흑체로에서 측정하였다. 1000K부터 2400K의 온도 영역에서 정확도는 .+-.2% 이내이고 정밀도는 가장 정밀한 결과를 주는 빠른 온도 계산법을 적용할 때 1600K에서 .+-.35K이다. 순간 온도 측정의 적용 예를 보이기 위하여 이 분광기를 정해진 조건에 있는 난류 연소의 측정에 적용하였다.

• 한국수소및신에너지학회논문집
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• 제5권2호
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• pp.111-119
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• 1994

Analysis of heat loss is needed to achieve the high performance and high efficiency in hydrogen engine. So, cooling losses at each part of the direct injection hydrogen fueled engine were measured to evaluate the behavior and distribution of heat loss. Unsteady instantaneous temperature and heat flux at cylinder head were measured by use of instantaneous temperature prove. And these results were compared with those of gasoline engine.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 추계학술대회 논문집
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• pp.255-259
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• 1996

This paper describes a system for measurement and control of a gas flow. In order to measure the flux of gas and control a vavle according to flux, this system was developed. This system is implemented on the personal computer and its environment is developed tool called TMS. This system includes a main program and Tele-Metering Unit for transmitting correcting flow value based on temperature and pressure in flow computer and AD converter for transmitting instantaneous flow rate, temperature and pressure as interface part of personal computer. This system was made by Visual C++ program. Using this system, inspected data for the recognition of transmitting flow value are generated on the screen, file and printer. The activity, reliability of this system was verified on Daegu-Citygas that aids the system for the acquisition of inspected data by realtime application.