• Journal of Energy Engineering
• /
• v.28 no.4
• /
• pp.35-41
• /
• 2019

In order to overcome these disadvantages, the halogen light source, which was previously used as a vehicle fog light, has increased power consumption and a short lifetime, and thus, an automobile light source is gradually being replaced with an LED. However, when the vehicle LED fog light is turned on, there is a disadvantage in reducing the life of the fog lamp due to the high heat generated from the LED. The heat generated by the LED inside the fog lamp is mainly emitted by the heatsink, but most of the remaining heat is released to the outside through convection. When cooling efficiency decreases due to convection, thermal energy generates heat to lenses, reflectors, and bezels, which are the main parts of lamps, or generates high temperatures in LED, thereby shortening the life of LED fog lights. In this study, we tried to improve the heat dissipation performance by convection in addition to the heat dissipation method by heat sink, and to determine the installation location of vents that can discharge the internal air or intake the external air of LED fog lamp for vehicle. Thermal fluid analysis was performed to ensure that the optimal data were reflected in the design. The average velocity of air increased in the order of Case3 and Case2 compared to Case1, which is the existing prototype, and the increase rate of Case3 was relatively higher than that of other cases. This is because the vents installed above and below the fog lamps induce the convective phenomena generated according to the temperature difference, and the heat is efficiently discharged with the increase of the air speed.

• Journal of Bio-Environment Control
• /
• v.15 no.2
• /
• pp.138-148
• /
• 2006

This study was carried out to evaluate the structural safety fur both the attached wind-protecting wall in greenhouse and the detached one installed outside. Regarding the attached wind-protecting wall in greenhouse, the analysis was conducted by doing a fluid-structure coupled field analysis using both CFX-5.7 and ANSYS 8.1 and also under the design condition of an instantaneous maximum wind velocity of $30.9m{\cdot}s^{-1}$. Three kinds of the width ranged from 30 to 90cm were considered in this study. With regard to the detached wind-protecting wall, the structural saffty was analyzed under the pressure difference of 1,117 Pa which corresponded to a wind velocity of $50m{\cdot}s^{-1}$ and the analytical results were also compared with theoretical ones. The result showed that there was little difference in the distribution of velocity overall and total pressure on the lateral side according to the width of the attached wind-protecting wall, but greenhouse with wind-protecting widths of 30 to 60cm has been reinforced to the extent of about 11% when compared with the case of being without the wall. The result also showed that the detached wind-protecting wall with a main-column interval of 3m was not stable so that it was necessary for the detached wind-protecting wall to be adequately reinforced to secure structural stability. Finally, there was great difference between analytical results and theoretical studies. The difference meant that there was some possibility of including errors when a theoretical study was done in three dimensional structure.

• Journal of the Korea Convergence Society
• /
• v.8 no.4
• /
• pp.199-205
• /
• 2017

In this study, the design analysis and the explosion welding were made into a clad sheet by the convergence method in order to solve the problem of heat transfer to the guide due to the heating of the 3D printer heating block. The shear strength of the clad plate material was tested and the results were analyzed by thermal analysis, thermal conductivity and thermal imaging. The following conclusions were obtained. 3D modeling of the heating block made of copper and titanium clad plate material The thermal analysis showed that the surface temperature of the filament guide area was lower than the heating block surface temperature. The average shear strength of copper and titanium clad plate material was measured and the average value of 195.6MPa was obtained. The thermal conductivity of the heating block made of copper and titanium clad plate material was measured three times and the average value was $62.52W/m{\cdot}K$. The surface temperature of the heating block made of copper and titanium clad plate material was measured by a thermal imaging camera at a maximum of $107.3^{\circ}C$ and $183.2^{\circ}C$ at the filament guide. The temperature distribution was $89^{\circ}C$ lower than that of the existing filament.

• Journal of the Economic Geographical Society of Korea
• /
• v.7 no.1
• /
• pp.65-81
• /
• 2004

Foreign direct investment (FDI) by firms has various motives in terms of the strategy for firms' long-term growth. This research uses the case study of Hyundai Motor Manufacturing Alabama to analyze the motives of the Korean auto industry's FDI in the U.S. and the locational factors that determined the selection of the site. This paper starts from the question of why Hyundai made the decision to invest in the U.S., which is not favorable in terms of production cost, especially considering that its exports to the U.S. have been on the increase. The results indicate that the strongest motive for the decision to invest in the U.S. was to ameliorate the trade friction between Korea and the U.S. Given that Hyundai depends on the U.S. market to a large extent for its exports, the foremost motive was to use local production in order to reduce the serious trade imbalance in the automobile sector between Korea and the U.S. in order that trade friction with the U.S. may be avoided and causes for trade disputes may be reduced. Other motives such as improving the access to local consumers were of secondary importance. After the selection of the country in which to invest, however, various factors were considered in the decision regarding the location of the plant, and incentives by local governments ultimately played a key role in this decision. The results imply that the Korean manufacturing industry's investment in the U.S. cannot be explained by traditional FDI theories and instead was greatly driven by a strategic defensive motive. In addition, the results confirm that the design of an appropriate incentive structure by host governments is important for attracting FDI.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.16 no.5
• /
• pp.3370-3377
• /
• 2015

FMECA(Failure Mode, Effects and Criticality Analysis) techniques to make quantitative evaluation of failure effects severity and criticality have been applied to systematic failure analysis for reliability improvement of train which should provide regular service and secure high level of safety as a mass transportation system. These FMECA techniques do not fully reflect the inherent train operation and maintenance circumstances because they are based on the FMECA standards devised for other industries such as automobile industry and FMECA standard dedicated to train industry has not been established yet. This paper analyzes FMECA standards for various industries, and suggests a FMECA technique dedicated to train industry which makes failure effect analysis and criticality analysis step by step and makes criticality analysis placing emphasis on the severity of the failure effect. The proposed technique is applied to FMECA of high-speed current breaker which is a core safety device of train using field failure data for 15 years of train maintenance. The FMECA results show that breakage of arc chute has the highest risk with 3rd severity class and 5th criticality class among all the components of high-speed circuit breaker. Damage and poor contact of electronic valve, and cylinder breakage with 3rd severity class and 4th criticality class are followed by. These results can be applied to improvement of design and maintenance process for high-speed circuit breaker of train.

• Land and Housing Review
• /
• v.4 no.2
• /
• pp.167-176
• /
• 2013

The City Complex Development and TOD originated from the Compact City are entrenched domestically. The New Urban Development such as these changes Structure of Urban space from the Automobile to the Public Transportation. Also, Transit-Oriented Development is drawing attention as sustainability because it has effects of Environment as Green growth. However, An empirical Study is insufficient about Influence Factors of Transit Oriented Development. Therefore This study sets up the Density spaced 1000m apart of Transit Oriented than the existing and did 7 Types considered of Accessibility, Complexity and Design Element according to the Factorial analysis. As a result, this study drew that (1) 'intraregional accessibility of public transit', (2) 'degree of development', 'pedestrian-friendly facility', (3) 'interzonal accessibility of public transit', (4) 'land-use of the city centre', 'complex using of rail station area', 'complementary public transit' are related 201 in number of the Subway stations according to the Multi-dimensional scaling.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.12 no.7
• /
• pp.1227-1234
• /
• 2008

In this paper is designed a 256-bit synchronous OTP(one-time programmable) memory required in application fields such as automobile appliance power ICs, display ICs, and CMOS image sensors. A 256-bit synchronous memory cell consists of NMOS capacitor as antifuse and access transistor without a high-voltage blocking transistor. A gate bias voltage circuit for the additional blocking transistor is removed since logic supply voltage VDD(=1.5V) and external program voltage VPPE(=5.5V) are used instead of conventional three supply voltages. And loading current of cell to be programmed increases according to RON(on resistance) of the antifuse and process variation in case of the voltage driving without current constraint in programming. Therefore, there is a problem that program voltage can be increased relatively due to resistive voltage drop on supply voltage VPP. And so loading current can be made to flow constantly by using the current driving method instead of the voltage driving counterpart in programming. Therefore, program voltage VPP can be lowered from 5.9V to 5.5V when measurement is done on the manufactured wafer. And the sens amplifier circuit is simplified by using the sens amplifier of clocked inverter type instead of the conventional current sent amplifier. The synchronous OTP of 256 bits is designed with Magnachip $0.13{\mu}m$ CMOS process. The layout area if $298.4{\times}314{\mu}m2$.

• Korean Journal of Optics and Photonics
• /
• v.26 no.2
• /
• pp.88-97
• /
• 2015

An omnidirectional optical system can be described as a special optical system that images in real time a panoramic image with an azimuthal angle of $360^{\circ}$ and the altitude angle corresponding to the upper and lower fields of view from the horizon line. In this paper, for easy fabrication and compact size, we designed and fabricated a catadioptric omnidirectional optical system consisting of the mirror part of a spherical mirror with a central hole (that is, obscuration), a plane mirror, the imaging lens part of 3 single spherical lenses, and a spherical doublet in the visible light spectrum. We evaluated its image performance by measuring the cut-off spatial frequency using automobile license plates, and the vertical field of view using an ISO 12233 chart. We achieved a catadioptric omnidirectional optical system with vertical field of view from $+53^{\circ}$ to $-17^{\circ}$ and an azimuthal angle of $360^{\circ}$. This optical system cleaniy imaged letters on a car's front license plate at the object distance of 3 meters, which corresponds to a cut-off spatial frequency of 135 lp/mm.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.20 no.3
• /
• pp.570-575
• /
• 2019

Active muffler is implemented by applying active noise control technique to reduce exhaust noise of automobile muffler. Conventional Filtered_x LMS algorithm has a problem that the degree of control filter becomes very large and convergence deteriorates when acoustic feedback is present. The recursive LMS algorithm can compensate for this problem because it can be easily diverted in the adaptive filter adaptation process. In this paper, the structure of the primary path and the secondary path transfer function is designed as the IIR filter to improve the convergence performance and the computational burden, and the stabilization filter algorithm is applied to secure stability which is a disadvantage of the IIR filter structure. The stabilization filter algorithm plays a role of pulling the pole into the unit circle to prevent the pole of the transfer function corresponding to the acoustic feedback from diverging during the adaptation process. In this way, the computational burden of the active muffler system and the convergence performance can be improved. In order to show the usefulness of the proposed system, we compared the performance of the proposed Filtered_x LMS algorithm with the performance of the proposed system for the exhaust sound of a diesel engine, which is a variable environment. Compared to conventional algorithm, proposed algorithm's computational burden is less than half, and convergence performances are more than 4 times.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.18 no.2
• /
• pp.129-143
• /
• 2019

As the importance of autonomous vehicle safety is emphasized, the application of ISO-26262, a development verification guideline for improving safety and reliability, and the safety verification of autonomous vehicles are becoming increasingly important, in particular, SAE standard level 3 or higher level autonomous vehicles detect and decision the surrounding environment instead of the human driver. Therefore, if there is and failure or malfunction in the autonomous driving function, safety may be seriously affected. So autonomous vehicles, it is essential to apply and verity the safety concept against failure and malfunctions. In this study, we study the fault injection scenarios for safety evaluation and verification of autonomous vehicles using ISO-26262 part3 process and STPA were studied and safety measures for safety concept design were studied through simulation bases fault injection test.