• Current Optics and Photonics
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• v.1 no.4
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• pp.351-357
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• 2017

This paper proposes a LED bicycle headlamp with a wide viewing angle to help bicyclists see the front effectively and because of its high visibility to reduce the risks of accidents around intersections or blind spots. The wide viewing angle was determined to be $28^{\circ}$ because it can illuminate a 5 m wide area 10 m away. Therefore, the road conditions of the intersection can be observed with the bicycle handlebar tilted slightly to the left or right. The headlamp has a compact reflector with a width of 30 mm, height of 27 mm, and length of 17 mm. Owing to its size, a change in the position of a light source leads to severe changes in light distribution. Therefore, the tolerance of the source position was analyzed by a simulation. The tolerance was ${\pm}0.5mm$ at the X, Y and Z axes within a less centered aiming range of ${\pm}1^{\circ}$. Finally, the prototype of the bicycle headlamp was made and the light distribution was measured by an automotive headlamp light measurement system. The experimental results indicate that the headlamp illuminates a 5 m wide area with an edge light of 3.2 lx as well as meeting the K-mark regulation.

• Journal of Drive and Control
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• v.15 no.3
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• pp.21-28
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• 2018

We propose a tension controller based on a time-delay estimation (TDE) technique for a winding machine. Firstly, we perform the necessary calculations to derive a mathematical model of the winding machine. In this sense, it is revealed that the roll radius of the winding machine is characteristically seen to be increasing or decreasing during the winding process. That being said, it is noted that the parameters of the winding machine are coupled and constantly changing during this process. Understandably then, it is noted that the model is shown to be nonlinear and time-varying. Secondly, we propose the way to apply the TDE based controller which is the so-called Time-delay Control (TDC). The TDC utilizes the time-delayed information intentionally to compensate the nonlinear and time-varying characteristics. As we have seen, the proposed controller consists of two parts: one is a TDE component, and the other is an error dynamics component which is defined by a user. In a computer simulation based on the Matlab/Simulink program, the proposed controller is compared with a conventional PID controller, which is widely used in the tension control of the winding machine. The proposed controller reduces the incidence of overshoot and steady-state error in the tension control, as compared to the conventional PID controller.

• Journal of the Korea Organic Resources Recycling Association
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• v.22 no.3
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• pp.60-67
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• 2014

Exhaust system used in toilet and cooking place of high riser public house is roof fan of two basic types : natural roof ventilator and natural/forced roof ventilator. Natural/forced roof ventilator has a motor in the rotary shaft. There are many high riser public house in Korea. These buildings were not viewed as being major contributors to exhaust pollutants producted in indoor. It was because many engineers thought that exhaust in high riser building depend on stack effect. This study investigates on stack pressure determined by exterior pressure and the difference pressure control in exhaust stack used in high riser public house. This paper focuses mainly on the effect of the time interval for power supply of motor installed in roof fan with function of natural wind velocity and of exhaust air volume of toilet. It is observed there are higher exhaust efficiency than the existing natural roof ventilator.

• Journal of the Korea Society for Simulation
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• v.24 no.4
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• pp.29-34
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• 2015

Electronic of military vehicle that had relied on pure machinery system is ongoing. A large part of electronic of small-sized military vehicle has been already commercialized, which will expand to large-sized military vehicle field. Design of solenoid valve for automatic transmission is significantly important for stable driving performance of military vehicle. This research aims to develop simulation method which is capable of predicting performance of solenoid valve quantitatively according to its variation of ATF temperature. The research has been conducted in line with Maxwell, a magnetic field analysis program, and AMESim, a hydraulic analysis program. After simulation, it turned out to have been very similar to the test result in temperature range which excludes high temperature (over $120^{\circ}C$) and extremely low temperature (below $-20^{\circ}C$).

• Journal of the Korea Society for Simulation
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• v.20 no.2
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• pp.67-76
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• 2011

Order picking in automotive service parts warehouses is considered to be the most labor-intensive operation. Such warehouses contain hundreds of thousands of items, but normally 20% of products contribute to about 80% of turnover according to Pareto's 80-20 principle. Therefore most fast moving items are located near an outbound area which is called the "Golden Zone". Order picking routing efficiency is related to productivity and labor cost. However, most companies use simple methods. In this paper, we describe a series of computational experiments over a set of test cases where, we compared various previously existing routing heuristics to an optimal algorithm. We focus on examining the influence of the golden zone on the performance and selection of routing methods. The results obtained show that the optimal routing method increases the productivity at least 17.2%, and all the routing methods have better performance as the pick up rate from the golden zone increases.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.40 no.4
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• pp.67-77
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• 2017

With the advent of the fourth industrial revolution, the digital transformation craze has intensified in diverse industries, such as finance, automotive, health care and agriculture. However, relative to industry demand, there is only few domestic research on digital transformation of small traders and no one has implemented empirical study on this field at all. Thus, the study conducted an empirical study to measure the digital transformation intention of domestic small traders. In the early days of domestic business start-ups, we searched for factors affecting the digital conversion intention of small business owners and designed an integrated framework to explain the causal relationship between factors. This study not only expanded and refined the scope of related research but also suggested the direction of another research that was not presented in previous research. However, there are limitations in many ways as much as the initial stage of a specific field of small business owners. There are limitations in explaining the overall perception of Korean small business owners. Therefore, in future studies, it is necessary to study more deeply by presenting more specific and various variables. In addition, although the number of respondents was sufficient in the process of empirical analysis, it is considered that the respondents are not enough to universalize the research result as a traditional small business person who did not convert all digital. It is necessary to carry out a comparative analysis by dividing the two groups in more detail and more specifically in the future study. The result of this study can suggest the direction for accelerating small traders' digital transformation intention in terms of practical view, and provide useful references which can support the theoretical foundation for researchers who will perform future related research in terms of academic view.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.11
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• pp.1297-1306
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• 2012

This work presents a 77 GHz radar transmitter for the automotive radar system. An integrated 13 GHz frequency synthesizer fabricated using 130 nm RF CMOS process drives a commercial W-band compound semiconductor monolithic multifunction amplifier(MPA), which includes a frequency multiplier by six to generate 77 GHz transmitting signal. The 13 GHz frequency synthesizer includes a high efficiency injection buffer of 4 dBm output power to drive the MPA. The output power of 77 GHz radar transmitter is higher than 13.99 dBm and the magnitude of the reference spur relative to the carrier is -36.45 dBc. The phase noise is -81 dBc/Hz at 1 MHz offset frequency from the carrier.

• Resources Recycling
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• v.27 no.2
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• pp.11-23
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• 2018

The need for remanufacturing automotive parts is required due to the depletion of resources, rising raw material prices and strengthening environmental regulations. For remanufacturing, stable supply and demand of core must be accompanied. At present, remanufacturing companies collect cores through various routes, but the recovery rate of cores from the End-of-Life Vehicles is low. If we can systematically collect cores from hundreds of thousands of ELVs that were generated each year, the recovery rate of the core for remanufacturing will be further improved. Therefore, in this paper, we tried to establish a classification system for the ELV as a method for collecting the cores from the ELV. First, we selected the elements affecting the classification and determined the scope for the evaluation. The final rating classification is established by calculating the weights among the influence elements. Finally, through the case study, the dismantling grade of the actual ELV was evaluated to derive the second grade.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.8 no.1
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• pp.1-7
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• 2014

In this study, the effect of the automotive haptic-seat technology which can transmit the driving information by the vibro-stimulus from the seat was investigated to overcome previous system's limitation relied on the visual and audial method and to help handicap driving. A prototype haptic seat covers with 30 coin-type motors and driver module were developed for this sake. A driving simulator on the 6-DOF motion-base was used for driving situation and we executed the seat vibro-stimulus test with 10 young participants who have normal tactile sense. The haptic recognition ratio by 30 locations was measured and analyzed in the result. The intensity of vibro-stimulus was adjusted by input voltage of motors (1.5V,2.5V,3.5V). All vibro-stimulus locations at 2.5V and 3.5V could be recognized by all participants and even in the lowest recognition ratio of 1.5V. The results showed that the seat vibration stimulus could be useful to transfer the drivers' information while driving.

• Elastomers and Composites
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• v.46 no.1
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• pp.29-36
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• 2011

The term 'thermal insulating materials' describes a class of materials which can improve the thermal efficiency by reducing the thermal conduction, convention and radiation between the inside and outside of the system. As a thermal insulating material, numerous industrial applications are possible including the automobile, aerospace, aviation, and petrochemical. Especially, the silica aerogel, with their superior thermal insulating behavior, has been widely used as thermal insulating materials. Because the mechanical properties of the silica aerogel cannot meet the industrial demand, use of the silica aerogel is limited. This article aims to review the thermal insulating materials and silica aerogel, and to introduce the silica aerogel/polymer composites.