• Journal of the Korean Society for Railway
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• v.16 no.2
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• pp.138-143
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• 2013

Recently, the demand for rail freight has gradually decreased. In particular, the demand in Korea for open freight cars, which classification includes gondola cars, hopper cars and gravel cars has been significantly reduced. The role of gondola cars in the rail transportation market shrank to 14.5% in 2010 from 23.3% in 2001. The transportation demand of gondola cars in the long term is expected to be reduced further. Because some gondola cars have been converted to container cars and various containers are being developed to transport bulk cargo by container cars. However, gondola cars still play an important role in rail freight transport. Therefore, the management planning of gondola cars is needed in order to prepare for the long-term declining demand. In this study, we propose a future direction for the management planning of gondola cars through the effectiveness analysis of gondola cars operation.

• Korean Journal of Optics and Photonics
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• v.4 no.2
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• pp.226-232
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• 1993

A broadband CARS system is constructed for shot by shot measurement of a full CARS spectrum, which consists of a frequency doubled Nd:Yag laser, broadband mode-less laser and optical multi-channel analyzer installed in a double grating monochromator. To increase the accuracy of CARS temperature measurement and get better the fitting goodness, we have measured the slit function of the detection system and determined the analytical functional form of the slit function. Accuracy of the CARS system for temperature measurement is evaluated from the difference between the best-fit temperature of CARS spectrum and temperature of thermocouple reading. The uncertainty of the temperature measurement is found to be less than 1.5% in temperature range from 300 K to 1300 K.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2006.06b
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• pp.345-348
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• 2006

LMTT (linear motor-based transfer technology) is horizontal transfer system in the maritime container terminal for the port automation. For LMTT system, shuttle cars are used instead of other types of cars. They are running on the routes which are stable on the terminal ground made of steel. The terminal scheduling complexity increases with the need of improving automation. It is necessary to make a good designed performance for the terminal system. This work presents a dispatching role using fuzzy logic for the shuttle cars. It considers the actual status of terminals and takes decisions on real time. A simulation is done to validate the role and two other dispatching rules to be compared.

• Journal of the KSME
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• v.33 no.12
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• pp.1043-1051
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• 1993

Nd:Yag 레이저의 제2고조파와 광대역 모드 없는 레이저를 광원으로 사용하고 이중회절발분광 기에 설치된 다채널광검출기로 분광된 CARS 스펙트럼을 레이저 펄스마다 측정 할 수 있는 광 대역 CARS 분광기를 제작하였다. CARS 온도측정 불확정도는 300K에서 1300K까지는 1.5% 이내였다. CARS 기술을 이용하여 분젠버너의 화염면에서의 온도 분포를 측정하였으며, 대향류 버너의 화염내부의 온도 분포 및 CO 농도분포를 측정하였다. 이러한 CARS 기술은 정상상태의 연소진단에 응용할 수 있을 뿐만 아니라 레이저 펄스마다 측정되는 온도의 분포함수를 조사하면 앞으로 난류연소의 진단에도 응용이 가능하며, 내연기관 등과 같이 연속폭발연소 상태의 기체의 온도나 농도 측정이 가능하다. 본 연구에서 연구된 CARS 기술의 온도 측정정확도는 약 2% 이 내이고 농도 측정은 측정기체의 농도가 상온에서는 약 0.1% 이상, 1500K 이상의 고온에서는 0.3%이상이면 가능하다.

• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.5
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• pp.9-16
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• 2001

End-gas temperatures were measured using CARS technique in a conventional DOHC spark- ignition engine fueled with PRF80. The measured pressure data were analyzed using band pass filter method. The measured CARS temperatures were compared with adiabatic core temperatures calculated from measured pressures. Significant heating by pre-flame reaction in the end gas zone was observed in the late part of compression stroke under both knocking and non-knocking conditions. CARS temperatures measured at 10 crank angle degree before knock occurrence was higher than adiabatic core temperatures. These results indicate that there exist some exothermic reactions in low pressure and temperature region. CARS temperatures began to be higher than the adiabatic core temperature when the end-gas temperatures reached look. The temperature elevation due to the pre-flame reaction correlated better with CARS temperature than with cylinder pressure.

• 한국연소학회:학술대회논문집
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• 2000.05a
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• pp.85-92
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• 2000

End-gas temperatures were measured using CARS technique in a conventional DOHC spark-ignition engine fueled with PRF80. The measured pressure data were analyzed using band pass filter method. The measured CARS temperatures were compared with adiabatic core temperatures calculated from measured pressure. Significant heating by pre-flame reaction in the end gas was observed in the late part of compression stroke under both knocking and non-knocking condition. CARS temperatures measured at 10 crank angle degree before knock occurrence was higher than adiabatic core temperatures. These results indicate that there exist some exothermic reactions in low pressure and temperature region. CARS temperatures began to be higher than the adiabatic core temperature when the end-gas temperatures reached 700 K. The temperature elevation due to the pre-flame reaction correlated better with CARS temperature than with cylinder pressure.

• Journal of Science Education
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• v.41 no.2
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• pp.179-194
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• 2017

The purpose of this study is to construct two equivalent science relevance recognition test tool after confirming the reliability and validity of the CARS(Changes in Attitude of Relevance to Science) questionnaire to determine the applicability of the items to Korean students and to compare gender and school differences. For this study, 59 items of the CARS scientific relevance test were translated and assigned to 787 middle and high school students (analyed the answer of 300 middle school students and 431 high school students). In order to determine the fit of the CARS question to Korean students and to overcome the limitation of the number of questions, we used the item-linking method of the Rasch model. By analyzing the results of the research, we constructed two equivalent scientific relevance recognition questionnaires of CARS-A and CARS-B with 25 items. The Pearson correlation coefficient of the Rasch scores of the two equivalent test was 0.78. The two types of scientific relevance recognition test tools generated through this study can be used to confirm students' attitude of scientific relevance to daily life, or to confirm the change after a certain class or grade. Through this study, we will discuss the implications of students' perceptions of science associations in science education, and the development and application of tools.

• Environmental Engineering Research
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• v.14 no.3
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• pp.180-185
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• 2009

Only limited information is available as regards to the exposure levels of naphthalene (polycyclic aromatic hydrocarbons, PAHs) and monocyclic aromatic hydrocarbons(MAHs) in the interiors of diesel-fueled passenger cars, while many studies investigated the exposure levels of various volatile organic compounds(VOCs) in the interiors of gasoline-fueled passenger cars or public buses. Present study was performed to supplement this deficiency by measuring naphthalene (as a representative of PAHs) and MAHs levels inside five diesel-fueled and five gasoline-fueled passenger cars while morning and evening commuting on real roadways. Each car was surveyed five times on different sampling days. The in-vehicle naphthalene levels were higher for the diesel-fueled cars as compared to gasoline-fueled cars, whereas the results were reversed for the in-vehicle MAH levels. The median cabin levels of diesel-fueled cars were 1.3, 7, 13, 4, and 6 ${\mu}g/m^3$ for naphthalene, benzene, toluene, ethyl benzene, and m,pxylene, respectively. With respect to gasoline-fueled cars, their respective levels were 0.7, 11, 21, 7, and 9 ${\mu}g/m^3$ . The median MAHs concentration ratios of gasoline-fueled cars to diesel-fueled cars ranged from 1.50 to 1.75, while the median naphthalene concentration ratio was estimated to be 0.54. In addition, there was no significant difference of both naphthalene and MAHs between the diesel-fueled cars, but the in-vehicle levels were significantly different between gasoline-fueled cars. The concentration levels of both naphthalene and MAHs were higher in the passenger cars than other non-industrial microenvironments. Consequently, it was confirmed that the cabins of both diesel-fueled and gasoline-fueled passenger cars are an important microenvironment associated with the exposure to naphthalene and MAHs.

• Journal of Multimedia Information System
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• v.5 no.2
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• pp.105-110
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• 2018

Autonomous cars require the integration of multiple communication systems for driving safety. Many carmakers unveil mirrorless concept cars aiming to replace rear and sideview mirrors in vehicles with camera monitoring systems, which eliminate blind spots and reduce risk. This paper presents optical vehicle-to-vehicle (V2V) communications for autonomous mirrorless cars. The flicker-free light emitting diode (LED) light sources, providing illumination and data transmission simultaneously, and a high speed camera are used as transmitters and a receiver in the OCC link, respectively. The rear side vehicle transmits both future action data and vehicle type data using a headlamp or daytime running light, and the front vehicle can receive OCC data from the camera that replaces side mirrors so as not to prevent accidents while driving. Experimental results showed that action and vehicle type information were sent by LED light sources successfully to the front vehicle's camera via the OCC link and proved that OCC-based V2V communications for mirrorless cars can be a viable solution to improve driving safety.

• Environmental and Resource Economics Review
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• v.22 no.1
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• pp.3-29
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• 2013

The purpose of this study is to estimate consumer preferences on hybrid cars and electric cars by employing a choice experiment reflecting the various market conditions, such as different projected market shares of green vehicles and $CO_2$ emission regulations. Depending on different market scenarios, we examine as to which attribute and individual characteristic affect the preferences of potential consumers on green vehicles and further, forecast the potential market shares of green cars. The primary results, estimated by a conditional logit and panel probit models, indicate that sales price, fuel cost, maximum speed, emission of air pollutants, fuel economy, and distance between fuel stations can significantly affect consumer's choice of environment-friendly cars. The second finding is that the unique features of electric cars might better appeal to consumers as the market conditions for electric cars are improved. Third, education, age, and gender can significantly affect individual preferences. Finally, as the market conditions become more favorable toward green cars, the forecasted market shares of hybrid and electric vehicles will increase up to 67% and 14%.