• Journal of KIBIM
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• v.6 no.2
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• pp.39-46
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• 2016

While institutional matters such as improvement on Basic Guidelines for Construction Safety are greatly concerned to reduce falling accidents at construction sites, there are short of studies on how to practically predict accident signs at construction sites and to preemptively prevent them. As one of existing accident prevention methods, it was attempted to build the early warning system based on standardized accident scenarios to control the situations. However, the investment cost was too high depending on the site situation, and it did not help construction workers directly since it was developed to mainly provide support operational work support to safety managers. In the long run, it would be possible to develop the augmented reality based accident prevention method from the worker perspective by extracting product information from BIM, visually rendering it along with site installation materials term and comparing it with the site situation. However, to make this method effective, the BIM model should be implemented first and the technology that can promptly process site situations should be introduced. Accordingly, it is necessary to identify risk signs through lightweight image processing to promptly respond only with currently available resources. In this study, it was intended to propose the system concept that identified potential risk factors of falling accidents by histogram equalization, which was known as the fastest image processing method presently, used visual words, which could enhance model classification by wording image records, to determine the risk factors and notified them to the work manager.

• Journal of the Korean Society of Industry Convergence
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• v.9 no.1
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• pp.61-66
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• 2006

In perspective of saving natural resource and energy, today's automobiles are in process of regenerating by smaller and lighter. In order to achieve the sufficiency on the consumption of the fuel, new mechanism and new assembly are required. Therefore the expectations on the new materials are very high. Especially, AI materials are widely used to reduce the weight. AI that is used in automobiles is mostly casting material, and according to the innovation of technique is in rapid development. AI Die casting is an important field as today's trend of lightweight on automobiles. One of the parts in steering system, Valve Housing plays a role of reduce the operating effort of drivers. Unfortunately, the Valve Housing which is widely reliable to the most automobiles are not developed at this moment in our automobile industry. Therefore, they are produced by casting method which cost three times or even more expensive in production. If Valve Housing, which is a part of steering system is produced by Gravity Casting, the space that manufacturing equipment will be increased, and more time and workers would be brought into service. For such reason, Die Casting would replace Gravity Casting in order to minimize cost of time, manpower, and working space.

• Transactions of the Korean Society of Automotive Engineers
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• v.20 no.3
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• pp.77-82
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• 2012

It is well known that the targeted fuel efficiency could only be achieved by more than 40% reduction of the vehicle weight through improved design and extensive utilization of lightweight materials. In order to obtain the goal of the weight reduction of automobiles, the researches about lighter and stronger rear sub-frame have been studied without sacrificing the safety of rear sub-frame. In this study, the weight reduction design process of rear sub-frame could be proposed based on the variation of von-Mises stress contour by substituting an AA6061 (aluminum 6061 alloy) having tensile strength of 310 MPa grade instead of SAPH440 steels. In addition, the stress ratio variations (stress over fatigue limit) of the rear sub-frame were examined and compared carefully. It could be reached that this approach method could be well established and be contributed for light-weight design guide and the optimum design conditions of the automotive rear sub-frame development.

• Journal of electromagnetic engineering and science
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• v.18 no.3
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• pp.188-198
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• 2018

In this study, we propose an approach for the design and satisfy the requirements of the fabrication of a small, lightweight, reliable, and stable ultra-wideband receiver for millimeter-wave bands and the contents of the approach. In this paper, we designed and fabricated a stable receiver with having low noise figure, flat gain characteristics, and low noise characteristics, suitable for millimeter-wave bands. The method uses the chip-and-wire process for the assembly and operation of a bare MMIC device. In order to compensate for the mismatch between the components used in the receiver, an amplifier, mixer, multiplier, and filter suitable for wideband frequency characteristics were designed and applied to the receiver. To improve the low frequency and narrow bandwidth of existing products, mathematical modeling of the wideband receiver was performed and based on this spurious signals generated from complex local oscillation signals were designed so as not to affect the RF path. In the ultra-wideband receiver, the gain was between 22.2 dB and 28.5 dB at Band A (input frequency, 18-26 GHz) with a flatness of approximately 6.3 dB, while the gain was between 21.9 dB and 26.0 dB at Band B (input frequency, 26-40 GHz) with a flatness of approximately 4.1 dB. The measured value of the noise figure at Band A was 7.92 dB and the maximum value of noise figure, measured at Band B was 8.58 dB. The leakage signal of the local oscillator (LO) was -97.3 dBm and -90 dBm at the 33 GHz and 44 GHz path, respectively. Measurement was made at the 15 GHz IF output of band A (LO, 33 GHz) and the suppression characteristic obtained through the measurement was approximately 30 dBc.

• Transactions of the Korean Society of Automotive Engineers
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• v.25 no.1
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• pp.11-18
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• 2017

In the present study, the low speed (4 km/h) crash behaviour of an aluminium bumper system was characterised by FE analyses based on the FMVSS 581, which regulates automotive bumpers. Two types of cross-sectional designs, i.e., Model 1, which contains a single rib and Model 2, double ribs, have been considered along with Al7021, 6082 and 6060 for the aluminium bumper back beam. Variations in thickness starting from 2 to 4 mm of the bumper system cross-section in the FE model was implemented in order to investigate the thickness effect on the bumper's crash behaviour.. Three kinds of design variables, namely, number of ribs, material and thickness, are considered. The FE analysis results are summarised with the maximum load and the Specific Energy Absorption (SEA) since they are the key factors in determining the crashworthiness of automotive structures. The results may also be able to indicate how to achieve lightweight structure of the automotive bumper system either directly or indirectly.

• Korean Institute of Interior Design Journal
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• no.13
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• pp.187-196
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• 1997

A Study on the Characteristics of the Modern Chair Design The features of the modern chair design results from the diverse life style unfolded as per the 20th century social structure and the change of the residential space, and new design has been being developed by the scientists and the artists in various fields through their cooperated work in a way. The field of the scientific or technical study and creation of arts can be developed where they can evoke the sympathy in the circumstances under which the various styles of both arts and science meet across, complement crash together, and grow up. The operation which can control in the network of such pluralistic sphere has been needed for a long period and it has been facing the needs from a time and society. The engineering furniture as the counterplan of the above has brought the value of materials into relief to the forms of human life by making the properties of matter the maximum value or changing it. It can be summarized as following characteristics in its materials and forms along as well as the 3 types (handycrafty, mechanical, and ecological expression) in process through the 20th century. 1. Characteristics in Materials elasticity of the chair as per the changes of the flexibility in the steel pipe development of systematic chair using the plasticity of the plywood, plastic, and wire lightweight due to the materials such as aluminum. 2. Formative characteristics formative simplicity for the increase of the function and the quality improvement such as sociality, productivity, environmental and aesthetic nature emphasis on the structure as per the architectural environment and tecniques pursuit of the forms as a container of the human body seeking for the formative values as the cultural symbols coping with the needs from thepluralistic social structure Furniture is not the makeup for convenience sake but most importantexpression as necessaries of our environments. It should identify itself always as per these kind of needs and also it should be able to used to keep the relation of such mutual division, otherwise the purchase of new furniture should be necessary according to every change of the existing situatiov. Our residence doesn't need the specific style but expresses only the properties of the dwellers.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.10
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• pp.975-981
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• 2017

Savings in weight using lightweight materials such as aluminum alloy can lead to increase fuel economy. However, compared to steel, aluminum alloys have a lower strength for an equivalent life cycle. To reduce the weight of automobiles, research is being performed on the fabrication of lighter and stronger torque struts without having to sacrifice the safety of automotive components. In this study, a weight reduction design process for torque struts is proposed that is based on varying von-Mises stress contours using an aluminum alloy (A356) having a tensile strength of 245 MPa, instead of STKM11A steels. The optimized design can reduce the weight of the original steel torque strut by over 42% and it can contribute to the design of light-weight components and to the safe design of torque struts.

• Proceedings of the KIPE Conference
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• 2003.11a
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• pp.214-217
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• 2003

The connectorless power supply system on that multi-contact causes confidence when the wiring reconstructed in the rear. As you see above, contact points between sets and indoor space cause inferior function of audio frequency so it needs to be eliminated. This paper explains the structure of connectorless power supply to supply the system with power crossing the air gap in the part of inductively in the connectorless power supply of both magnetic and electrical model. To get maximum output of electrical load, compensating capacitor compensates to show inter-inductance, lequeage-inductance reducing the track-inductance and access the conditions for resonance. At that time it accesses the maximum electric power. The small change of the value of compensating capacitor causes the changes of maximum electric power. Here the power electronics technology is used not only in the industrial machinery but also in the home appliances so the switching power supply is used to actualize the miniaturization, lightweight, and high efficiency. Generally the condenser input methods are widely used in the rectification circuit of switching power supply, but condenser input method generate great quantity of high frequency components because with this method the current flows in the power input filtering condenser only around value of peak of ac input voltage. To solve these problems, installation of power factor improve circuit on the front of filtering capacitence was considered. Several methods were suggested regarding, but the active filter method which makes smalliging and highly power factor possible are the produce main stream. IC for power factor improvement can be utilized by CMOS process proposing low power consumption. When the high power factor is considered seriously in the power factor improvement circuit, active filter method is selected. In the active filter method, the boost converter is used. Regarding this ·the boost converter is needed.

• Journal of Internet Computing and Services
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• v.10 no.4
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• pp.127-138
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• 2009

Mobile web applications are being used and changed rapidly due to the growth of mobile device performance. But, cost of development environment and standards make the high development cost and low productivity. It is main reason that the design and implementation of the applications are more time consuming than general computing environments. In this paper, we propose MWeb(MobileWeb)-Framework based on the agile methodology and Ruby on Rails that is a kind of framework for supporting mobile web application development using mobile web standards. This work consists of the mobile web development architecture and agile process model. MWeb-Framework will support the same user experience to the different devices. We validates the framework by implementing the case studies through suggested mobile web development framework. As a result, we can develop the mobile web applications with productivity and quality. In the future, we will suggest how to make the MWeb-Framework standardization and practically apply the frameworks the various case studies to improve framework potentially problems.

• Journal of Korean Society of Steel Construction
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• v.14 no.5 s.60
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• pp.647-656
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• 2002

High-strength steel in steel bridges is the key to achieving cost-efficiency because it facilitates lightweight construction and rationalizes structure. The future of high-strength steel is bright, with its use projected to expand. As such, it is necessary to evaluate precisely various factors affecting the process of fabricating high-strength steel, i.e., welding heat, strain hardening, and weldability and performance of the welded joints. This study therefore performed the maximum hardness test and y-groove weld crack test using welding processes such as SAW, FCAW, and GMAW, in order to investigate the welding performance and characteristics of welded Joints or high-strength steel produced in Korea such as SM570, POSTEN60, and POSTEN80. In addition, a series of welding tests was carried out to estimate the tensile strength, bending characteristics, absorbed energy, and hardness in welded joints.