• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.2
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• pp.175-181
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• 2014

A four-link mechanism consisting of torsion bars is used for opening the trunk lid in most midsize sedans. When the weight of the lid is in equilibrium with the spring force exerted by torsion bars, the lid stops opening at a pop-up height. However, the actual pop-up height has large deviations from the specified height even with the same parts in the same car model, which leads to quality issues. Automotive manufacturers have experienced this deviation problem despite much effort to resolve it. In this research, we developed a multi-body dynamics model for the analysis of pop-up deviation of a trunk lid with torsion bars, which can simulate the actual pop-up motion of the trunk lid by considering kinematic constraints of the motion and friction forces in joints. We could also determine the most important factor that governs the pop-up height by sensitivity analysis of all parts. The developed system can be used for the analysis of other trunk lid systems to control the tolerance of parts.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.3
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• pp.967-976
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• 2012

This study presents a model to minimize vibration and noise of powertrain mount on a compact car which has the application of Stop & Go performance, in order to reduce CO2 and achieve better fuel-efficiency in accordance with the environmental regulations in automotive industries. In the first step, we analyze the powertrain mount system of the automobile "A" and present variables about rubber stiffness applied on powertrain mount using the Taguchi method. In the next step, we verify the optimization of vibration and noise which meet Stop & Go performance using the AHP(Analytic Hierarchy Process) method on the proto products for each variable. Using this validation system on the initial stage of the powertrain mount design, it is expected that we can grasp vibration and noise problems caused by engine movements and control them effectively without engineering know-how about powertrain mount rubber stiffness.

• Transactions of the Korean Society of Automotive Engineers
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• v.25 no.2
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• pp.133-139
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• 2017

The timing chain system, which is a typical power transmission technology applied to a vehicle, has been widely used by the automotive industry because it is normally designed to last a car's lifetime. However, the timing chain system may cause some problems due to the shape of the chains and the polygonal behavior on contact between the chain and the sprocket. In addition, noise and vibration caused by transmission error are the most typical problems encountered by major automotive manufacturers and they are considered as the main source of customer complaint. The initial tension of the chain-sprocket system is thought to be the main cause of transmission error, and it is regarded as the source of engine vibration and noise. The initial tension of the chain system should be controlled carefully since a low initial tension can cause twisting, which may lead to a system malfunction, while a high initial tension can reduce the service life due to a worn down contact surface. In this paper, the kinematic analysis model is generated with various initial tensions, which are controlled by changing the shape of the fixed guide with the largest contact surface with chain. The results showed that the transmission error was minimized on a particular range of initial tension, and the tendency showed that the error changed with a higher sensitivity at a lower initial tension.

• Journal of Korea Port Economic Association
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• v.39 no.2
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• pp.165-178
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• 2023

This paper presented a management model for continuous development and co-prosperity between freight car transportation companies and consigned car owners, which are the subjects of the consignment system. A structural equation-based questionnaire was created to measure the variables necessary for establishing a management model, such as business owners' perceptions of each other and their needs for improvement, by analyzing the internal and external environment of the freight transport market and conducting surveys of freight companies and consigned vehicle owners. As a result of the analysis, it was confirmed that the rationality of the consignment system did not have a significant effect on financial performance or the level of transportation service, while the external environment and compensation system of the transportation business had a significant impact on financial performance and level of transportation service. In addition, the rationality of the consignment system does not affect the improvement of the relationship between project entities, but it does affect the level of trust. It was confirmed that the external environment and compensation system of the transport business have an effect on both relationship improvement and trust level improvement. It was found that the level of trust affects financial performance, and relationship improvement does not affect both financial performance and transportation service level. It is necessary to manage the consignment system based on the confirmed analysis results in order for the domestic freight company and the consigned vehicle owner to coexist and develop each other in the truck transportation market.

• Korean Journal of Food Science and Technology
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• v.47 no.1
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• pp.95-102
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• 2015

The Maillard reaction is a non-enzymatic reaction between amino and carbonyl groups. During milk processing, lactose reacts with milk protein through this reaction. Infant formulas (IFs) are milk-based products processed with heat-treatments, including spray-drying and sterilization. Because IFs contain higher Maillard reaction products (MRPs) than breast milk, formula-fed infants are subject to higher MRP exposure than breast milk-fed ones. In this study, we investigated the optimization of conditions for minimal MRP formation with the addition of $\small{L}$-carnitine ($\small{L}$-car), pyridoxine hydrochloride (PH), and $\small{DL}$-${\alpha}$-tocopheryl acetate (${\alpha}$-T) in an IF model system. MRP formation was monitored by response surface methodology using fluorescence intensity (FI) and 5-hydroxymethylfurfural (HMF) content. The optimal condition for minimizing the formation of MRPs was with $2.3{\mu}M$ $\small{L}$-car, $15.8{\mu}M$ PH, and $20.6{\mu}M$ ${\alpha}$-T. Under this condition, the predicted values were 77.4% FI and 248.7 ppb HMF.

• Journal of Korean Society of Transportation
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• v.32 no.2
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• pp.93-105
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• 2014

This study evaluated the relative efficiency of mobile emission reduction countermeasures through a Data Envelopment Analysis (DEA) approach and determined the priority of countermeasures based on the efficiency. Ten countermeasures currently applied for reducing greenhouse gases and air pollution materials were selected to make a scenario for evaluation. The reduction volumes of four air pollution materials(CO, HC, NOX, PM) and three greenhouse gases($CO_2$, $CH_4$, $N_2O$) for the year 2027, which is the last target year, were calculated by utilizing both a travel demand forecasting model and variable composite emission factors with respect to future travel patterns. To estimate the relative effectiveness of reduction countermeasures, this study performed a super-efficiency analysis among the Data Envelopment Analysis models. It was found that expanding the participation in self car-free day program was the most superior reduction measurement with 1.879 efficiency points, followed by expansion of exclusive bus lanes and promotion of CNG hybrid bus diffusion. The results of this study do not represent the absolute data for prioritizing reduction countermeasures for mobile greenhouse gases and air pollution materials. However, in terms of presenting the direction for establishing reduction countermeasures, this study may contribute to policy selection for mobile emission reduction measures and the establishment of systematic mid- and long-term reduction measures.

• Journal of Convergence for Information Technology
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• v.11 no.7
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• pp.111-117
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• 2021

This research work is to suggest the experimental results capable of solving an initial unsuitability of combustion and environment in a constant volume combustion chamber by using LFG(Land Fill Gas) which consists of 40% CO₂ and 60% CH₄. The experimental condition is set as 0.9~1.6 of air-fuel ratio, 3bar of combustion pressure, 25℃ of room temperature, methane for using gas, and 2.5~4.5 of Pre-chamber hole sizes. As a result, it can be seen that diffusion of initial flame is significantly increased by M3.0 model comparing with other one. The reason for the characteristics is that orifice effect is extremely improved by 0.9, 1.0, and 1.2 of air-fuel ratio comparing with other one. Consequently, this experiment is shown that M3.0 model is partially capable of improving combustion performance than a conventional ignition plug in case of applying to LFG with Pre-chamber design.

• Journal of the Korea Convergence Society
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• v.9 no.4
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• pp.143-150
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• 2018

This work conducted the experimental analysis on ultrasonic acoustic matching in order to measure the accuracy of gaseous fuel level values. The experimental devices were used as 12V-DC supply, control T1 board, oscilloscope (DS01072B), ultrasonic probe and pattern table. The research models were designed by ceramic assay which can determine the transmitting and receiving energies. The result of the ringing area could verify the increased characteristics in the order of D (0.180m) < E (0.184m) < B (0.204m) < A (0.234m) < F (0.244m) < C (0.247m) models based on initial 2.9V of the maximum peak voltage. From the experimental results, the model designed by Ø21*3+2t of the matching layer was notable in that the most outstanding directivity energy could be created.

• Journal of Internet Computing and Services
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• v.17 no.4
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• pp.11-17
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• 2016

In this paper, we proposed a multi-viewer system with multiple HD cameras based AVB(Audio Video Bridge) ethernet cable using IP networking, and FPGA(Xilinx Zynq 702) for bus safety systems. This AVB (IEEE802.1BA) system can be designed for the low latency based on FPGA, and transmit real-time with HD video and audio signals in a vehicle network. The proposed multi-viewer platform can multiplex H.264 video signals from 4 wide-angle HD cameras with existed ethernet 1Gbps. and 2-wire 100Mbps cables. The design of Zynq 702 based low latency to H.264 AVC CODEC was proposed for the minimization of time-delay in the HD video transmission of car area network, too. And the performance of PSNR(Peak Signal-to-noise-ratio) was analyzed with the reference model JM for encoding and decoding results in H.264 AVC CODEC. These PSNR values can be confirmed according the theoretical and HW result from the signal of H.264 AVC CODEC based on Zynq 702 the multi-viewer with multiple cameras. As a result, proposed AVB multi-viewer platform with multiple cameras can be used for the surveillance of audio and video around a bus for the safety due to the low latency of H.264 AVC CODEC design.

• Journal of Climate Change Research
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• v.3 no.2
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• pp.153-159
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• 2012

CFC-12 used in mobile air conditioning(MAC) system has been replaced by R-134a, a type of HFC refrigerant, from 1991 to 1994. R-134a has since been widely used as a refrigerant of a mobile air conditioner. However, it is one of the six main green house gases listed in Kyoto Protocol, which makes it imperative to regulate its emission and develop alternative refrigerants. In this study, the concentration of leaked R-134a was measured using VT(Variable Temperature) shed and Running loss test shed to analyze the level of air conditioner refrigerant leaked in a vehicle. According to the analysis of the concentration of R-134a leaked from a vehicle parked, annual leakage amount of R-134a was in the range of 6.46~13.28 g/yr. The figure was similar with the leakage from the mobile air conditioning system currently used. In a study using the same vehicle model, a vehicle equipped with dual evaporation system had a higher leakage rate of refrigerant than a vehicle with a single evaporation system. It appears that the added fittings and joints of the dual evaporator system led to higher leakage rate. Besides, the analysis of the change in R-134a concentration under various car speed found that more refrigerant leaked under high speed(100km/hr) and but the volume of the wind did not affect to the variation of refrigerant leakage.