• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.6
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• pp.683-689
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• 2014

The present study conducted a parameter effect analysis of low-frequency squeal noise using a numerical simulation. The finite element program ABAQUS was used to calculate the dynamic instability based on a complex eigenvalue analysis. A total of five parameters, including the chassis, wear, piston, material property, and contact condition, were selected to identify the factor effects on a low-frequency squeal noise between 2.5 and 3.1 kHz. The present study found the dominant level of each factor through an analysis of the means in the context of the experiment design.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.10 no.4
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• pp.63-68
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• 2010

Mobile devices like iphone, ipad, kindle, and PDA are used as everyday tool. In the mobile environment, smart phones and other mobile units are also used as a tool for protection or infringement of personal information. Therefore, smart monitoring technology is required to protect personal information and privacy. On the other hand, with smart phones and the mobile environment, diverse application technologies are realized on hardware and software platforms. Therefore, this paper designs the network structure that forms privacy trust zone, and based on this, deals with the monitoring and monitoring prevention system with a focus on CCTV, through which this paper proposes a system that provides privacy trust zone information and its utilization which is capable of smart monitoring.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.11
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• pp.1019-1028
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• 2013

The BWS (broadcast website) data broadcasting service for terrestrial DMB (digital multimedia broadcasting) has a great advantage that it can provide a website like service through broadcast without web traffic to a plurality of receiving terminals. However, the value of BWS has not been recognized due to the development of mobile communication technology and changes in the environment, where mobile web services through smart devices such as smart phones and pads are common. Recently, various hybrid service technologies provided through hybrid broadcasting, a fusion of broadcasting and communications, have been developed. In this paper, we propose a scalable BWS dividing the hierarchy of BWS into transmission layers and present its application for hybrid DMB data broadcasting services.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.11
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• pp.1066-1074
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• 2004

A vibration isolation system for a large reverberation chamber (1,228 $m^3$ and 1,000 ton) has been installed and verified. The reverberation chamber generates loud noise and induces high level of vibration while performing spacecraft acoustic reliability tests. The isolation system prevents vibration transfer from the chamber to the enclosure buildings. This paper describes design process and commissioning experiments of the system. Design criteria have been derived from rigid body model of the chamber. The stiffness of neoprene pads has been selected by employing finite element analysis of the reverberant chamber and isolation system. A total of 21 neoprene pads have been installed between the chamber and supporting Pedestals. A sand bag of 800kg was dropped on the chamber floor to measure the natural frequency of the isolation system. While 136.9 dB noise is generated in the chamber, absolute transmissibility of the isolation system has been measured. The measured natural frequency of the chamber is 10.2Hz, which is 80% of the predicted value. Overall transmissibility at working frequency range (25∼10.000 Hz) is less than -12.4 dB.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.10
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• pp.832-835
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• 2017

In this paper, V-band differential low noise amplifier(LNA) using 65-nm CMOS process for high speed wireless data communication is presented. The LNA is composed of 3-stage common-source differential amplifiers with neutralization of feedback capacitances using MOS capacitors and impedance matching utilizing transformers. The fabricated LNA has a peak gain of 23 dB at 63 GHz and 3 dB bandwidth of 6 GHz. The chip area of LNA is $0.3mm^2$ and the LNA consumes 32 mW DC power from 1.2 V supply voltage.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.3
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• pp.203-207
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• 2008

Chemical mechanical polishing (CMP) allows the planarization of wafers with two or more materials. There are many elements such as slurry, polishing pad, process parameters and conditioning in CMP process. Especially, polishing pad is considered as one of the most important consumables because this affects its performances such as WIWNU(within wafer non-uniformity) and MRR(material removal rate). In polishing pad, grooves and pores on its surface affect distribution of slurry, flow and profile of MRR on wafer. A subject of this investigation is to apply CMP for planarization of shallow trench isolation structure using microstructure(MS) pad. MS pad is designed to have uniform structure on its surface and manufactured by micro-molding technology. And then STI CMP performances such as pattern selectivity, erosion and comer rounding are evaluated.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.356-357
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• 2005

Chemical mechanical polishing (CMP) allows the planarization of wafers with two or more materials at their surfaces. Especially, polishing pad is considered as one of the most important consumables because of its properties. Subject of this investigation is to apply CMP for planarization of shallow trench isolation structure using microstructure pad. Microstructure pad is designed to have uniform structure on its surface and fabricated by micro-molding technology. And then STI CMP performances such as oxide dishing and nitride corner rounding are evaluated.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.481-482
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• 2006

Chemical-mechanical polishing, the dominant technology for LSI planarization, is trending to play an important function in micro-electro mechanical systems (MEMS). However, MEMS CMP process has a couple of different characteristics in comparison to LSI device CMP since the feature size of MEMS is bigger than that of LSI devices. Preliminary CMP tests are performed to understand material removal rate (MRR) with blanket wafer under a couple of polishing pressure and velocity. Based on the blanket CMP data, this paper focuses on the consumable approach to enhance MEMS CMP by the adjustment of slurry and pad. As a mechanical tool, newly developed microstructured (MS) pad is applied to compare with conventional pad (IC 1400-k Nitta-Haas), which is fabricated by micro melding method of polyurethane. To understand the CMP characteristics in real time, in-situ friction force monitoring system was used. Finally, the topography change of poly-si MEMS structures is compared according to the pattern density, size and shape as polishing time goes on.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.4
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• pp.218-221
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• 2015

Power MOSFETs (metal oxide semiconductor field effect transistor) operate as energy control semiconductor switches. In order to reduce energy loss of the device during switch-on state, it is essential to increase its conductance. In this study we have investigated a structure to reduce the on-resistance characteristics of the MOSFET. We have a proposed MOSFET structure of active cells region buried under the gate pad. The measurement are carried out with a EDS to analyze electrical characteristics, and the proposed MOSFET are compared with the conventional MOSFET. The result of proposed MOSFET was 1.68[${\Omega}$], showing 10% improvement compared to the conventional MOSFET at 700[V].

• Journal of the Korea Safety Management & Science
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• v.17 no.2
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• pp.235-240
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• 2015

Using a progressive die of the multi-stage drawing product, It was experiments for the Influence of the Products Roundness on the die pad process Safety die model, obstacle countermeasure research safety die design When the die pad is independent structure, Sidewall thickness of the inside 2stage, 3stage, 4stage of the product is thicker, the thickness of the inside 1stage and the bottom is thinner. it was become unstable beacuse the inside 1stage related to the Products Roundness is thinner. When the die pad is Integrated structure, Sidewall thickness of the inside 1stage, 2stage of the product is thicker, and Sidewall 3stage and 4stage was a thin. it was become unstable beacuse the inside 3stage related to the Products Roundness is thinner. Therefore, The appropriate combination of and integrated independent is required for each process.