• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.8
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• pp.26-33
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• 2017

Vehicle communication can facilitate efficient coordination among vehicles on the road and enable future vehicular applications such as vehicle safety enhancement, infotainment, or even autonomous driving. In the $3^{rd}$ Generation Partnership Project (3GPP), many studies focus on long term evolution (LTE)-based vehicle communication. Because vehicle speed is high enough to cause severe channel distortion in vehicle-to-vehicle (V2V) environments. We can utilize channel estimation methods to approach a reliable vehicle communication systems. Conventional channel estimation schemes can be categorized as least-squares (LS), decision-directed channel estimation (DDCE), spectral temporal averaging (STA), and smoothing methods. In this study, we propose a smart channel estimation scheme in LTE-based V2V environments. The channel estimation scheme, based on an LTE uplink system, uses a demodulation reference signal (DMRS) as the pilot symbol. Unlike conventional channel estimation schemes, we propose an adaptive smoothing channel estimation scheme (ASCE) using quadratic smoothing (QS) of the pilot symbols, which estimates a channel with greater accuracy and adaptively estimates channels in data symbols. In simulation results, the proposed ASCE scheme shows improved overall performance in terms of the normalized mean square error (NMSE) and bit error rate (BER) relative to conventional schemes.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.9 no.3
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• pp.1-11
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• 2010

Traffic broadcasting is using a usual traffic information announcement when giving its information to users on the road and for the provision of information useful to drivers, a clear criteria of how to judge with information from informers needs to be established from the perspective of users. In this study, to give some available criteria for current announcement which often causes confusion, cognitive characteristics were investigated and analyzed based on judgment criteria which are commonly felt by correspondents, participants in traffic broadcasting and drivers. The result requires the provision of information that is relied on an average speed where drivers feel little cognitive difference and found a classification where a smooth traffic flow is more than 60km/h, going slow 40~60km/h and congested state less than 40km/h respectively. And from the study of 35 traffic information announcement for different traffic situations, 8 cases of smooth state and 9 cases of congested state were clearly classified but the rest 18 cases of comment were ambiguously perceived by drivers and which requires the necessity of a announcement that uses directly the word of 'smooth', 'slow', and 'congestion' in the actual expression of slow driving. The future study should be focused on the establishment of more definite criteria by representation of nearly real traffic flow, provision of traffic information announcement and the analysis of cognitive response through car dynamic simulators and the kinds.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.16 no.2
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• pp.73-82
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• 2017

In this research, we tried to check the applicability of a Chow test to the linear models which are generated in the process of transportation planning or traffic flow analyses. The Chow test is a very popular statistical method which is being used to see if the coefficients from two separate linear regression models are equal or not. In order to prove the effectiveness of the Chow test, we found the linear relationships between speed and density under the situations such as driving in daytime and in nighttime on a rainy day. Based on the two months of Joong-Bu Expressway traffic data, we proved that the Chow test is useful to testify the similarity between two linear regression models. And this statistical tool seems to be able to have a very important role in traffic flow analysis or in transportation planning process. Finally, we expect the Chow test be implemented even to the non-linear regression models or to the multi-variate models.

• The korean journal of orthodontics
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• v.37 no.2 s.121
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• pp.89-97
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• 2007

Objective: The purpose of this study was to measure the insertion torque of orthodontic miniscrews regarding changes in their shape, diameter, and length. Methods: Torque values were measured during continuous insertion of the miniscrews into solid rigid polyurethane foam, using a torque tester of driving motor type with a regular speed of 3 rpm. Orthodontic miniscrews (Biomaterials Korea, Seoul, Korea) of cylindrical type and taper type were used. Results: Increasing the length and diameter of the miniscrews increased the maximum insertion torque value in both cylindrical and taper type screws. Insertion torque was increased at the incomplete head of the cylindrical type screw, and at the tapered part of the taper type screw. The insertion torque value of miniscrews was influenced most by diameter, then shape and length. As a result, it was shown that the diameter of the screw had the most influence on insertion torque, and the taper type screw had a higher torque value than the cylindrical type screw. Conclusion: Therefore, a large diameter or taper type screw are adequate for areas of thin cortical bone with a large interdental space, and a small diameter or cylindrical type screw are adequate in the mandibular molar area or the midpalatal area having thick cortical bone.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.18 no.6
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• pp.31-42
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• 2019

Among the driving information recorded in the event data recorder (EDR), the speed information of the vehicle before the traffic accident is a very important factor that determines the punishment of the driver of the accident vehicle, the identification of the offender and the victim, and the possibility of avoiding the accident. Also, by analyzing the EDR data, the deceleration of the accident vehicle can be analyzed. In this study, the results of the braking test of the previous study and the analysis of the EDR data of the traffic accident vehicle were compared to suggest an appropriate deceleration value applicable to the calculation of the stopping distance. As a result of the braking test of the vehicle equipped with ABS of the previous study, the average deceleration of the vehicle was 0.79g ~ 0.94g. In addition, the deceleration value was calculated from 0.92g to 0.94g in the recent automobile safety evaluation braking test conducted by the Korea Automobile Testing & Research Institute. In addition, the deceleration value of 0.55g ~ 0.71g was calculated through the analysis of EDR data performed in this study, and the value was smaller than the deceleration value measured in the braking experiment of the previous study.

• Journal of Bio-Environment Control
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• v.14 no.1
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• pp.7-14
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• 2005

This study was conducted to develop a chain conveyor-type, row-spacing system for a plant factory. The developed system was evaluated for its practical use in growing plants. Results are intended to provide technical suggestions on the row spacing for hydroponically grown vegetables in a plant factory. The designed row-spacing system for a plant factory could be adjusted by four stages with a conveying speed range of $5.3\~15.8cm{\cdot}s^{-1}$ and with a row-space range of 10-25cm. The torque of driving shaft was measured with a torque range of 11.7-33.3 N$\cdot$m according as a trough weight changes with a range of $17\~935$ N. A measured value was $5.9\~9.8\;N{\cdot}m$ lower than a theoretical value. Travel reduction rate was shown up $1.6\~1.9\%$. The conveying time of trough was shown up 2.24 seconds in case that the designed value was 2.26 seconds. The system was evaluated to be functioning effectively according to the initial design factors in the test.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.4
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• pp.737-752
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• 1992

Analysis of elasto-dynamic deformation of flexible linkage mechanism is conducted using the finite element method. The equations of motion of the system are derived from the static structural problem in which dynamic inertia, gravitational and driving forces are treated as external loads. Linear spring model is included in the formulation of equation of motions to represent the effects of deformation of elastic bearings of revolute joints on the system behavior. A computer program is constructed and applied to analyze a specific crank-lever 4-bar mechanism. The algorithm of the program is as follows. First, the natural frequencies and the mode shapes of the system are calculated by solving the eigenproblem of the mechanism system which can be considered as a static structure by assuming the input shaft (crank shaft) to be fixed at any given configuration of mechanism. And finally, the elasto-dynamic deformation of the whole system is obtained using mode superposition method for the case of constant input speed. The effect of geometric stiffness on the mechamism is included in the program with the axial forces of links obtained through the quasi-static displacement analysis. It is found that the geometric stiffness exerts an important effect upon the elasto-dynamic behavior of the flexible linkage mechanism. Elastic deformation of bearing lowers the natural frequencies of the system, resulting smaller elastic displacement at the mid-point of the links and bigger elestic displacement at the ends of the links than rigid bearing. The above investigation of flexible linkage mechanism shows that the effects of the elastic deformation of bearing on the mechanism should be considered to design the mechanism which satisfies more preciously the purpose and the condition of design.

• The Journal of the Convergence on Culture Technology
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• v.6 no.3
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• pp.431-436
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• 2020

Information service organizations that provide science and technology information with a relatively short information life cycle for free or paid are in need of reflecting rapidly changing user needs and behaviors and grafting the latest technologies. The purpose of this study is to derive improvements for each system by comparing and analyzing general recognition of science and technology information users' domestic and foreign science and technology information sites and importance by science and technology information attributes. A total of 816 users of science and technology information participated in the online survey, and the collected data were analyzed by quantitative methods including IPA (Importance Performance Analysis) technique. The importance was evaluated by the impact value calculated through regression analysis. As a result of data analysis, the general recognition of users on science and technology information sites was relatively high in national science and technology information services, and Google Scholar and Science Direct were also high. Google Scholar was found to have more strength than improvement. A better understanding of the user's preferred system is a good driving force for improving the lack of existing systems. It is necessary to improve the information retrieval of the science and technology information service system, that is, to improve the search speed and functions, and also to improve the user interface with improved convenience and usability.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.12
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• pp.1-9
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• 2009

A full adders is an important component in applications of digital signal processors and microprocessors. Thus it is imperative to improve the power dissipation and operating speed for designing a full adder. We propose a new adder with modified version of conventional static CMOS and pass transistor logic. The carry-out generation circuit of the proposed full adder is different from the conventional XOR-XNOR structure. The output Cout of module III is generated from input A, B and Cin directly without passing through module I as in conventional structure. Thus output Cout is faster by reducing operation step. The proposed module III uses the static CMOS logic style, which results full-swing operation and good driving capability. The proposed 1bit full adder has the advantages over the conventional static CMOS, CPL, TGA, TFA, HPSC, 14T, and TSAC logic. The delay time is improved by 4.3% comparing to the best value known. PDP(power delay product) is improved by 9.8% comparing to the best value. Simulation has been carried out using a $0.18{\mu}m$ CMOS design rule for simulation purposes. The physical design has been verified using HSPICE.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.12 no.5
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• pp.73-86
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• 2013

This study aimed to measure the behaviors of drivers approaching a roundabout and analyze the characteristics of them. For these objectives, a system to measure the in-vehicle behaviors of a driver when he/she approaches a roundabout. The reliability of the system was analyzed, and the result were applied to a driving test in a roundabout. The result suggested that drivers showed cognitive responses to the accelerator pedal $176.0{\pm}35.18m$ ahead of the approach zone. And they showed cognitive responses to the brake pedal and the speed of the vehicle $121.0{\pm}26.01m$ and $66.0{\pm}18.31m$ ahead of the approach zone, respectively. As for drivers' cognitive changes between the start and end points of their cognitive responses at a roundabout, the standard deviation of the time of response was ${\pm}26.01m$, and the standard deviation of the end point was ${\pm}7.03m$, which meant that there was a 3.71-fold gap between the two deviation values. During the test, differences among the drivers were observed, but no difference was observed among trails.