• 한국자동차공학회논문집
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• 제23권1호
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• pp.130-138
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• 2015

Despite of recently strengthened vehicle emission regulations, NOx emissions are not decreased in urban areas because of discrepancies between certification emission test modes and real driving conditions. Thus, researches on RDE-LDV (Real-driving Emission-Light-duty Vehicle) have been conducted actively using PEMS (Portable Emissions Measurement Systems). In the present study, NOx emissions were measured for 5 Korean light duty vehicles for real driving conditions including city, combined, highway, and up-downhill test route. Emission characteristics were analyzed for averaged NOx emissions per unit driving distance of each driving test routes. Furthermore, MAW (Moving Average Window) method based on $CO_2$ emissions from WLTC, which will be supported for EU regulations, was utilized. It was revealed that DRs (deviation ratios) for diesel vehicles (i.e., 5.1 ~ 8.4) were greater than gasoline vehicles (less than 0.15). Especially DR of diesel vehicle for up-downhill test route was 8.4, which indicates severe NOx emissions.

• 한국분무공학회지
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• 제21권4호
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• pp.200-206
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• 2016

Recently, the certification procedure for exhaust emission regulation of LDV has tested with the NEDC mode in the laboratory. But the on-road exhaust emissions exceed the standard emission limits. Therefore, it is important to analyze the real-driving emissions (RDE) with a portable emissions measurement system (PEMS). In present study, the on-road emissions were measured with a PEMS and evaluated by moving averaging window (MAW) method. Also, it was compared with the $CO_2$ and $NO_x$ emissions for real-driving and test modes from euro-6 light-duty vehicles equipped with SCR and LNT systems. In results, on-road $NO_x$ emission has been 2.3-10.0 times higher than the standard $NO_x$ emission limit on NEDC mode. The reason was that the test modes did not reflect traffic and various real-driving patterns sufficiently.

• 항공우주기술
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• 제6권1호
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• pp.173-181
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• 2007

단위 장비 수준에서 시스템 수준에 이르기까지 통제되는 KSLV-I 2단부의 복사성 방사/감응 특성은 탑재되는 위성, 발사체 1단부, 그리고 우주센터에 설치되고 운용되는 지상장비 및 외부 통신망의 정상동작을 보장하기 위하여 전 주파수 대역에 대해 시험 및 관리되어야 한다. KSLV-I과 하부시스템에서 방사되는 비의도성 잡음은 각각의 요구규격에 정의된 제한치 보다 작도록 제한되어야 할 뿐만 아니라 시스템의 특성을 정확히 검증하기 위한 적절한 시험 및 평가 방법도 개발되어야 한다. 본 논문에서는 KSLV-I 2단부 엔지니어링 모델의 전자파적합성 확보를 위해 도출된 복사성 방사와 복사성 감응에 대한 시험규격, 측정방법 그리고 시험 결과가 제시된다.

• 한국해양공학회지
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• 제7권2호
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• pp.121-130
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• 1993

A study off riction welding of high speed steel(SKH 51) bar for blade side to carbon steel(STC 3)bar for shank side was carried out experimentally through tensile test, hardness test, microstructure, and acoustic emission (AE) test. So, this paper deals with optimizing the welding conditions and the real-time quality (strength) evaluation of friction weleded joints by acoustic emission technique. The results obtained are summarized as follows: (1) For friction welded joints of SKH 51to STC 3 steel bars, the total upset (U) increases linearly with an increase of heating time (t sub(1)). (2) The determined optimum welding conditions are heating time (t sub(1)) 7-9 sec, upsetting time (t sub(2)) 5 sec, heating pressure(P sub(1)) 12 kg sub(f)mm supper(2), upsetting pressure (P sub(2)) 15 kg sub(f) mm supper(2) and rotating speed (n) 2, 000 rpm, resulting in a computed relationship between the tensile strength of the joint .sigma. (kg sub(f) mm supper(2)) and the heating time t sub(1) (sec) as the following. sigma.=2.39t sub(1)

• 한국항공우주학회지
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• 제35권4호
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• pp.329-337
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• 2007

초록 1 본 논문은 전자파 방사 및 내성 요구조건을 만족하도록 개발되어야 하는 위성발사체용 GPS 수신기 시스템에 대하여 수행된 전자파시험을 다루고 있다. 수차례에 걸쳐서 수행된 전자파시험을 통하여 전자파환경에서의 성능이 개선된 GPS 수신기 시스템은 주어진 전자파환경 규격을 모두 만족하였다. 본 논문은 수행된 전자파시험의 Part I으로 시험개요와 MIL-STD-461E에 주어진 CE102, CE106, RE102 규격에 대한 방사시험 결과를 제시한다.

• 한국자동차공학회논문집
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• 제10권3호
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• pp.70-76
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• 2002

This study focus on the effect of engine specification, driving conditions and the vehicle type on the idle emission characteristics. In order to obtain the characteristics of exhaust emissions, 1,260 vehicles of spark ignition engine are sampled and investigated. The exhaust emissions are measured with a CO/HC emission gas analyzer. The Sl engine vehicles are investigated by the effect of various exhaust emission parameters such as vehicle milage, engine specification, valve trains and fuels. The results show that the amount of CO and HC emission is not directly related to the driving mileage of the vehicle. However, the engine specifications and fuels such as the type of valve train and piston displacement have influence on the exhaust emissions. In addition, the LPG vehicle emits more CO and HC than gasoline vehicle. Based on the test results of SI vehicles, the influence of excess air and displacement volume are discussed.

• 한국축산시설환경학회지
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• 제4권2호
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• pp.183-191
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• 1998

This study was carried out to elucidate the correlation between Germination Index(G.I.) and CO2 emission for evaluation of the maturity of compost products. 13 compost samples was used for this experiment. The G.I. test was carried out on the basis of T-N 200ppm. As a result of this research, we found that CO2 emission method was good simple indicator for evaluation of maturity of compost materials, in spite of G.I. The obtain results are summarized as follows ; 1. The correlation value between the G.I. and the CO2 emission was R2 = 0.776. 2. The correlation value between EC(Electric Conductivity) and G.I. was R2 =0.7. 3. The equation calculated from G.I. and CO2 emission was G.I. = -16.7(InCO2) - 6.87. 4. From these results, we found the possibility of estimation for the value of G.I.(T-N 200ppm) from CO2 emission volume under specific condition.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2000년도 춘계학술발표대회 논문집
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• pp.159-162
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• 2000

Interfacial and microfailure properties of carbon fiber/epoxy matrix composites were evaluated using both tensile fragmentation and compressive Broutman tests with acoustic emission (AE). Amino-silane and maleic anhydride polymeric coupling agents were used via the dipping and electrodeposition (ED), respectively. Both coupling agents exhibited higher improvements in interfacial shear strength (IFSS) under tensile tests than compressive cases. However, ED treatment showed higher IFSS improvement than dipping case under both tensile and compressive test. The typical microfailure modes including fiber break, matrix cracking, and interlayer failure were observed during tensile test, whereas the diagonal slippage in fiber ends was observed during compressive test. For both the untreated and treated cases AE distributions were separated well under tensile testing. On the other hand, AE distributions were rather closer under compressive tests because of the difference in failure energies between tensile and compressive loading. Under both loading conditions, fiber breaks occurred around just before and after yielding point. Maximum AE voltage fur the waveform of carbon or basalt fiber breakage under tensile tests exhibited much larger than those under compressive tests.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.1349-1352
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• 2005

This paper is to investigate a defect for thermal barrier coating layers by acoustic emission method in 4-point bending test. The two-layer thermal barrier coating is composed of $150\mu{m}\;CoNiCrAlY\;bond\;coating\;by\;vacuum\;plasma\;spray(VPS)\;process\;and\;250\mu{m}\;ZrO_2-8wt%Y_2O_3$ ceramic coating layer by air plasma spray(APS) process on Inconel-718. The specimen prepared by cyclic thermal test(500, 1000, 2000cycle) at $1050^{\circ}C$ The AE monitoring system is composed of PICO type sensor, a wide band pre-amplifier(40dB), PC and AE DSP(16/32 PAC) board. The AE event, amplitude, Cumulative energy and count of coating specimens is evaluated according to cyclic thermal test.

• 한국공작기계학회논문집
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• 제15권4호
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• pp.98-104
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• 2006

In this paper, for the purpose of investigation the acoustic emission(AE) behaviors during resistance spot welding process and tension test of spec steels. As the results present the resistance spot welding method that can get suitable welding qualities or structural integrity estimating method. The resistance spot welding process consists of several stages: set-down of the electrodes; squeeze; current flow; forging; hold time; and lift-off. Various types of AE signals are produced during each of these stages. For tensile-shear test and cross tensile test in resistance spot welded specimens, fracture pa 야 ems are produced: tear fracture; shear fracture; and plug fracture. Tensile-shear specimens strength appeared higher than cross tensile specimens one. In case of tensile-shear specimen happened tear fracture that crack happens in most lower plate. Also, in case of cross tensile specimens, upper plate and lower plate are detached perfect fracture was exposed increases a little as acting force is lower than ordinary welding condition. Therefore, the structure which is combined by resistance spot welding confirmed that welding design must attain so that shear stress may can interact mainly.