• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.4
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• pp.159-165
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• 2013

One of the leading causes of night time automobile accidents is the darkness of surroundings. Headlamps play a critical role in casting light and providing drivers with visibility. Headlamp design and new technology have been developed recently as research has been actively carried out to increase headlamp recognition. This study statistically analyzes irradiation distance using computer simulation by categorizing headlamps applied in domestic automobiles in the last decade by year, light source, form, vehicle type, and height of installation. After analyzing results of irradiation distance, it appears irradiation distance has been increased by approximately 10m in the last decade. This increase in irradiation distance is predicted to decrease night time accidents by allowing more time to recognize potential causes of accidents.

• Journal of Korean Neurosurgical Society
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• v.29 no.8
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• pp.1050-1054
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• 2000

Objective : The incidence of head injury has been increasing in the rural area. The author investigated the clinical features and difficulties in care of the acute head-injured patients in this area. Method and Material : The authors performed a retrospective review of radiological data and clinical records in patients with mild to moderate head injury. Cause, type of craniocerebral injury, delayed intracranial lesions, complications, its relation to alcohol abuse, and outcome were analyzed. Results : In total of 68 cases, 20(29.4%) victims were associated with acute alcohol intoxication. Motor vehicle accident was the leading cause of head injury and the most common craniocerebral lesion was basilar skull fracture. Eight(11.8%) patients showed delayed radiological and clinical deterioration and 40(58.8%) were followed-up regularly after discharge. The subdural hygroma was commonly noted in the elderly and alcoholics. Causes of thirty events that resulted in an atypical and difficult neurosurgical practice were as follows : delayed admission, premature discharge against doctor's request, refusal of radiological studies and admission, misunderstanding of disease entity, and unreasonable desire of transfer to tertiary hospitals. Inaccurate initial diagnoses were made by emergency doctors in twenty patients. During the course of treatment, there were a few complications such as alcohol withdrawal, acute otitis media, cerebrospinal fistula, facial weakness, and posttraumatic seizure. Outcome was good in 60(88.2%) patients. Conclusion : Most of minor head trauma patients in this series have shown good results, but we have to consider some possible complications and delayed intracranial lesions in these patients that should be managed with special cautions with various kinds of treatment difficulties.

• Advances in aircraft and spacecraft science
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• v.2 no.1
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• pp.45-56
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• 2015

The attitude aerodynamic control is an important subject in the design of an aerospace plane. Usually, at high altitudes, this control is fulfilled by thrusters so that the implementation of an aerodynamic control of the vehicle has the advantage of reducing the amount of thrusters fuel to be loaded on board. In the present paper, the efficiency of a wing-flap has been evaluated considering a NACA 0010 airfoil with a trailing edge flap of length equal to 35% of the chord. Computational tests have been carried out in hypersonic, rarefied flow by a direct simulation Monte Carlo code at the altitudes of 65 and 85 km, in the range of angle of attack 0-40 deg. and with flap deflection equal to 0, 15 and 30 deg.. Effects of the flap deflection have been quantified by the variations of the aerodynamic force and of the longitudinal moment. The shock wave-boundary layer interaction and the shock wave-shock wave interaction have been also considered. A possible interaction of the leading edge shock wave and of the shock wave arising from the vertex of the convex corner, produced on the lower surface of the airfoil when the flap is deflected, generates a shock wave whose intensity is stronger than those of the two interacting shock waves. This produces a consistent increment of pressure and heat flux on the lower surface of the flap, where a thermal protection system is required.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.5
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• pp.89-94
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• 2003

Rolling stock structures such as bogie frame and car body play an important role for the support of vehicle leading. In general, more than 25 years' durability is needed for them. A lot of study has been carried out for the prediction of the fatigue life of the bogie frame and car body in experimental and theoretical domains. One of the new methods is a probabilistic fatigue lift evaluation. The objective of this paper is to estimate the fatigue lift of the bogie frame of an electric car, which was developed by the Korea Railroad Research Institute (KRRI). We used two approaches. In the first approach probabilistic distribution of S-N curve and limit state function of the equivalent stress of the measured stress spectra are used. In the second approach, limit state function is also used. And load spectra measured by strain gauges are approximated by the two-parameter Weibull distribution. Other probabilistic variables are represented by log-normal and normal distributions. Finally, reliability index and structural integrity of the bogie frame are estimated.

• Wind and Structures
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• v.11 no.5
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• pp.345-359
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• 2008

An experimental investigation of the flow over the rectangular body located in close proximity to a ground board was reported using the particle image velocimetry (PIV) technique. The present experiments were conducted in a closed-loop open surface water channel with the Reynolds number, $Re_H=1.2{\times}10^4$ based on the model height. In addition to the PIV measurements, flow visualization studies were also carried out. The PIV technique provided instantaneous and time-averaged velocity vectors map, vorticity contours, streamline topology and turbulent quantities at various locations in the near wake. In the vertical symmetry plane, the upperbody flow is separated from the sharp top leading edge of the model and formed a large reverse flow region on the upper surface of the model. The flow structure downstream of the model has asymmetric double vortices. In the horizontal symmetry plane, identical separated flow regions occur on both vertical side walls and a pair of primary recirculatory bubbles dominates the wake region.

• Proceedings of the KWS Conference
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• 2006.10a
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• pp.216-218
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• 2006

The application of aluminium alloy is increasing for lightweight and high quality transport vehicle. In this study, therefore, it is intended to apply the high speed hybrid welding method for marine grade aluminium alloy(A5083) used for shipbuilding that consists of 3 kW CW Nd:YAG laser and MIG welding process. For this purpose, the characteristics of process parameters(laser & arc combine angle and focal position of hybrid head to specimen) are investigated for hybrid fillet joint. This study also describes determination of heat distribution using finite element model of the T-joint fillet weld using the in-house solver which has been validated for different type of welding problems.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.97-100
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• 2009

Cold flow and ignition tests were performed for a technology demonstration model of a 75-tonf thrust chamber which is a candidate liquid rocket engine for a next Korea Space Launch Vehicle. The test facility was modified to support the new concepts of the thrust chamber such as ignition system, film cooling and LOx leading supply. The hydrodynamic characteristics of the supply pipelines, thrust chamber and igniter as well as the filling time of the propellants were obtained through the cold flow tests on the LOx and kerosene and the ignition cyclogram was determined using the results. The ignition test was successfully accomplished according to the cyclogram and therefore, a basic information was obtained for further hot firing tests.

• Journal of the Korean Ceramic Society
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• v.51 no.1
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• pp.19-24
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• 2014

Three-layer porous alumina-mullite composites with a symmetric gradient porosity are prepared using a controlled freeze/gel-casting method. In this work, tertiary-butyl alcohol (TBA) and coal fly ash with an appropriate addition of $Al_2O_3$ were used as the freezing vehicle and the starting material, respectively. When sintered at $1300-1500^{\circ}C$, unidirectional macro-pore channels aligned regularly along the growth direction of solid TBA were developed. Simultaneously, the pore channels were surrounded by less porous structured walls. A high degree of solid loading resulted in low porosity and a small pore size, leading to higher compressive strength. The sintered porous layered composite exhibited improved compressive strength with a slight decrease in its porosity. After sintering at $1500^{\circ}C$, the layered composite consisting of outer layers with a 50 wt% solid loading showed the highest compressive strength ($90.8{\pm}3.7MPa$) with porosity of approximately 26.4%.

• Journal of the Ergonomics Society of Korea
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• v.28 no.2
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• pp.9-16
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• 2009

The aim of this study was to evaluate the effects of the driving performance and workload according to changing driving environment and types of steering wheel. Twelve drivers who participated in this study consisted of two groups; six Japanese as the left-lane drivers who was accustomed to driving on left-hand side of the road, and six Europeans, Americans, and Korean as the right-lane drivers who was accustomed to driving on right-hand side of the road. They were asked to operate a driving simulator while using two different types of steering wheel (for the left-hand side driving and the right-hand side driving). During the experiment, a range of data were measured including driving performance, mental workload, and eye movements which were recorded in order to identify the amount of time looking towards the in-vehicle route guidance. Results indicated that the use of the steering wheel by parallel moving led to increase high attentional demand and worse glance behavior to traffic signs for the left-lane drivers. In the case of the right-lane drivers, the effects by changing driving direction were more effective than the types of steering wheel due to their habit or traits.

• Journal of the Korean Society of Safety
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• v.24 no.3
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• pp.65-70
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• 2009

In-vehicle route guidance information(RGI) systems have been developed with the advancement of the information and communication technologies. However, the RGI is provided by a pre-determined option, drivers occasionally pass the target intersection owing to non- or late- recognizing it. The purpose of this experiment is to examine the position of driver's tum signal operation and intersection recognition approaching at the target intersection which is difficult to identify as a preliminary research on developing the additional RGI connecting with the tum signal control. The field experiment was conducted to measure distances of the turn signal operation and intersection recognition from the target intersection according to driving lanes and landmarks at adjacent intersection. And, glance behavior to the car navigation display was evaluated by using an eye camera. The results indicate that drivers operate the turn signal after confirming a landmark in the case of the intersection with it. However, most case of driving, drivers operate the tum signal at 40 to 50m before coming to the target. To provide the additional RGI, when drivers do not operate the tum signal approaching at the target intersection based on the results, is expected to improve the traffic safety and the comfort for drivers.