Assessment of risky driving caused by the amount of time focused on an in-vehicle display system

Korea is currently experiencing a rapidly increasing distribution rate of in-vehicle display devices, such as navigation or DMB displays, owing to remarkable advances in IT. At the same time, the number of traffic accidents and traffic violations is increasing due to the distraction of drivers’ attention by such devices. In particular, in-vehicle display devices such as navigation systems temporarily distract drivers’ visual or cognitive attention when they perform a unit task. Accordingly, it is necessary to prepare adequate standards to regulate in-vehicle display devices, especially in Korea. There are few empirical studies that have employed experiments to support such regulation. In this study, an experiment was conducted using a driving simulator to establish the proper standards regarding the maximum distraction time per unit task that can be allowed without causing any disturbance in safe driving. A total of 25 participants participated in the experiment. The distraction time was controlled by asking participants to perform the two tasks at once: while participants were driving as a primary task, they performed secondary task that count the number of intersections between the start point and the arrival point displayed on the screen. The results showed that the 2.0 second condition differed from the controlled condition in the deviation in the distance from the preceding vehicle, speed, and steering wheel movement, whereas there were no differences between the controlled condition and the 1.0 or 1.5 second condition. Finally, the limitations of the study and the implications of the findings with regard to future studies and application of the Korean version of guidelines for in-vehicle display devices are discussed.     

Measuring the safety impact of road infrastructure systems on driver behavior: Vehicle instrumentation and real world driving experiment

Featured in this pilot experimental study is the construction and design of an instrumented vehicle that is able to capture vehicle trajectory data with an extremely high level of accuracy and time resolution. Once constructed and properly instrumented, the various data collection systems were integrated with one another and a driving experiment was conducted on northern Virginia roadways with 18 participants taking part in the study. Trajectory data were collected for each of the drivers as they traversed a predefined loop of four roadway segments with varying numbers of lanes and varying shoulder widths. Data collected from the experiment were then used to calibrate the parameters of the prospect theory car-following model through a genetic algorithm calibration procedure. Once all model parameters were successfully calibrated, significance testing was carried out to determine the impacts that the varying roadway infrastructure had on driving behavior. Results indicated that there were significant changes in behavior when comparing one lane roadways to their two lane counterparts—specifically in cases where the roadway featured a wide shoulder. Additional testing was conducted to ensure that there was no variation based on gender, as nine study participants were female and nine were male. The successfulness of this first study conducted with the newly constructed instrumented vehicle creates the opportunity for a variety of additional studies to be conducted in the future.     

A study on the causes of rear-end collision based on an analysis of driver behavior

The increasing number of traffic fatalities in recent years has become a serious social problem, making it imperative to find scientific and effective ways of preventing accidents on the road. An important step in this direction is to identify the causes underlying each accident pattern. This paper presents a study of the causes of rear-end collision, focusing on the danger of the driver's mis-judgment of the brake timing in approaching a preceding vehicle. The results indicated that drivers showed inappropriate judgment in some situations.     

A numerical study of the derailment caused by collision of a rail vehicle using a virtual testing model

This study investigated the wheel-lift and roll-over derailment mechanisms caused by train collisions using a precise virtual testing model (VTM) of a Korean high-speed train. The VTM was a complex, nonlinear finite element model composed of the shell, beam, solid, spring, and surface contact elements for the car body, bogies, suspensions, and wheel–rail interfaces. The VTM was validated by checking the errors in the total energy and the dynamic responses of the spring elements. To achieve a quick, dynamic relaxation of the dead weight of the VTM before the collision analysis, the artificial damping method and the artificial force method were introduced and numerically evaluated. The surface-to-surface contact model from commercial software, Ls-Dyna, was applied to the VTM in order to simulate the derailment mechanisms caused by collision accidents. The numerical analyses of the VTM colliding with a large deformable obstacle or a rigid wall revealed for the first time that a mixed slip/roll-over-type derailment mechanism generally occurs. Furthermore, the simulation results were consistent with the results from a simplified theoretical derailment model of a wheel set.     

An experimental study on the dynamic characteristics of cylinder head gaskets for diesel engine: dynamic characteristics in heating and cooling temperature cycle by abrupt change of water during steady operation

Experiments on a small, one-cylinder high-speed diesel engine were performed by changing the temperature of cooling water and also by changing the material and configuration of the cylinder head gaskets. Three kinds of cylinder head gaskets were made. The temperature was abruptly changed and the temperatures at several points of the cylinder head gasket and its peripheral region, the relative displacement between cylinder head and cylinder block, the loads of the cylinder head bolts, the indicator diagram, the pressure of gasket surface and combustion gas leakage were measured. The sealing characteristics in the transient state and the steady state of the cooling water temperature were investigated from an experimental standpoint. The effect of the temperature differences between the cylinder head, cylinder block and head bolts on the loads of the head bolts and the relative displacement between the cylinder head and cylinder block were observed for the test gaskets.     

固化剂加固土性能的研究

依据固化剂加固土的试验，研究结果，分析了新型固化剂加固土的强度形成机理，同时通过试验，研究了新型固化剂加固土的路用性能，并同石灰加固土进行了对比分析。     

不中断交通实施铰接板桥加固的研究

在分析铰接析铰缝破坏原因的基础上，提出了不中断交通实施铰接板桥加固的方案，其中包括剪力钢筋法和横向预应力法，并给出剪力钢筋法的加固效果。     

A study on the weld characteristics of 5182 aluminum alloy by Nd:Yag laser welding with filler wire for car bodies

Defects such as porosity, underfill, and magnesium loss occur during laser welding of 5182 aluminum alloy. To compensate for these problems, AA5356 filler wire was used in our present work. To investigate the weld characteristics of the filler wire, experiments were performed with laser power, welding speed, and wire feed rate as the control variables. Bead appearance, bead shape, penetration depth, tensile strength, and the Erichsen ratio were observed as weld characteristic variables. The range of full penetration was reduced as laser power decreased and welding speed and wire feed rate increased. Without filler wire, full penetration was formed under all conditions. However, with filler wire, the range of conditions necessary to form full penetration was reduced as the wire feed rate increased because the heat input was used to melt both of the filler wire and the base metal. Filler wire increased the tensile strength and the Erichsen ratio. Using analysis of variance (ANOVA), it was shown that laser power had a greater influence on tensile strength and the Erichsen ratio among the three control variables. It was also found that tensile strength was closely related to the Erichsen ratio because the coefficient of correlation was 0.899.     

岳增才口述:从中集东岳创始人到投资合伙人,从做企业到做平台

中集东岳、万事达创始人,济宁银行股东,江铃华岳董事……岳增才的身上有很多的签,如今他的名片上新的身份是联合投资人。作为梁山专用车第一代创业者,岳增才从农机维修到挂车生产,从率先进入国家"目录"到推动东岳、万事达并入中集,他的每一次选择和判断都颇具战略远见和创新性。     

A study on the formation of vertical vortex in the cylinder of an I.C. engine using CFD: Effect of intake valve closing timing

Air flows in the intake ports and cylinders of a four-valve gasoline engine were numerically analyzed by means of an original CFD code named “GTT”. In this code, the k-ε turbulence model was used and the Chakravarthy-Osher 3rd order TVD scheme was applied to the convection terms in all the governing differential equations. The validity of the code was confirmed by comparing the calculated results of the mean velocity and turbulence intensity with the measured ones by means of LDV. Using the present code, the effect of the intake valve closing timing on the formation of vertical vortex in the cylinder of a four-valve engine was investigated. It was found that the turbulence energy in the combustion chamber near compression TDC can be increased by the retardation of intake valve closing timing in the case of intense vertical vortex, because the vertical vortex is intensified by the back flow from the cylinder to the intake ports.     

The travel behaviour of ride-sourcing users,and their perception of the usefulness of ride-sourcing based on the users' previous modes of transport: A case study in Bandung City,Indonesia

Research provides evidence that ride-sourcing has not only substituted for private transport but also public transport. For further investigation of this substitution effect, this paper explores the travel behaviour of ride-sourcing users and those users' socio-demographic characteristics as well as perception of the usefulness of ride-sourcing based on the users' previous modes of transport before ride-sourcing existed. For these purposes, the study collected data using a questionnaire survey in Bandung City in 2018. We found that substitution from public transport exists for younger travellers, while substitution from private transport is most likely associated with infrequent and higher-income travellers. We also found open spaces, a green environment and high interaction society in the residential environments that have more association with high-income travellers, thus associated with lower use of ride-sourcing for former private transport users. This study found that travellers who resided in areas with similar, high-income characteristics tend to have a positive appreciation of ride-sourcing. It appears that the increasing perceived usefulness does not straightforwardly increase the frequency of usage. Therefore, travellers who lived in a more high-end and active social environment might appreciate the role of ride-sourcing services in some of their trips that complement another daily trip.