• 한국ITS학회:학술대회논문집
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• 2010.05a
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• pp.98-101
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• 2010

• Proceedings of the Korea Society of Design Studies Conference
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• 2003.05a
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• pp.14-15
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• 2003

• 한국ITS학회:학술대회논문집
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• 2004.11a
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• pp.89-92
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• 2004

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.9 s.112
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• pp.821-828
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• 2006

In this paper, we investigated SAR(Specific Absorption Rate) value variation by the position and size of the loop-type ground located in a test mobile handset. We carried out simulations on SAR value with loop-type grounds in rear case of a mobile handset, and obtained results showed that different positions and sizes of loop-type grounds had different SAR values. Among investigated positions and sizes of loop-type grounds, the small size case-C showed the best performance; i.e., it showed a decrease efficiency of 8.70 %. And in this case, it showed the highest induced electric-field distribution in the loop-type ground. In the simulation, the folding angle was set to $160^{\circ}$.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.5
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• pp.475-483
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• 2013

In this paper, a coupled-fed monopole antenna for LTE/WWAN mobile handset applications is presented. The antenna consists of a monopole, a coupling strip, a feeding pad, a stub, and a shorting strip. The basic resonance of the monopole combines with the resonance formed by the coupling that occurs between the coupling strip and the feeding pad to include LTE700(698~787 MHz), GSM850(824~894 MHz), and GSM900(890~960 MHz) bands. The resonance of the stub combines with the harmonics of the monopole to include GSM1800(1,710~1,880 MHz), GSM1900(1,850~1,990 MHz), and UMTS(1,920~2,170 MHz) bands. Therefore, the proposed antenna is suitable as antenna for hexa-band mobile handset applications, covering LTE700, GSM850, GSM900, GSM1800, GSM1900, and UMTS bands. A stable and omni-directional radiation pattern with reasonable gains is observed within the operating bandwidth.

• Proceedings of the KIEE Conference
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• 2008.10b
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• pp.137-138
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• 2008

This paper proposes the modified image contrast enhancement technique for small-sized display of mobile handset. Sample images are user interface images, in which scaled up wVGA($800{\times}480$) from qVGA($320{\times}240$) that we can see easily in mobile handset. The display size of mobile handset is relatively small, so the goal of this paper is to simplify image contrast enhancement algorithm based on conventional HE (Histogram Equalization) algorithm and improve computational effectiveness to minimize power consumption in real hardware IC. In this paper, we adopt HE technique, which is classical and widely used for image contrast enhancement. At first, the input frame image is partitioned to temporal sub-frames and then analyzes gray level histogram of each sub-frame. In case that the analyzed histogram of some sub-frames deviates so much from reference level (it means that the sub-frame image components consist of too bright ones or dark ones), apply DHE(Dynamic Histogram Equalization) algorithm. In the other case, apply classical Histogram Linearization (or Global HE) algorithm. Also we compare the HE technique with gamma LUT (Look-Up Table) method, which is known as the simplest technique to enhance image contrast.

• Journal of Korea Multimedia Society
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• v.11 no.10
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• pp.1436-1445
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• 2008

Currently, mobile handset embeds many communication modules including CDMA and Bluetooth, and many applications are developed based on these modules. In this paper, we study about wireless vehicle diagnosis software and user interface based on bluetooth system on mobile handset. We developed Bluetooth communication system on protocol converter between OBD(On Board Diagnostics)-II system. Based on this system, we can communicate ECU(Engine Control Unit) and mobile device based on windows .NET compact framework platform. Therefore we can easily diagnose vehicle state and obtain engine data. All user interface and vehicle diagnosis systems on mobile handset are developed under windows .NET compact framework platform. Using this system we achieved several improvements over existing vehicle diagnostic system; 1) the software download and upgrade can be achieve on wireless environment, 2) no additional diagnostic devices are requires, which saves additional cost and we can diagnose the vehicle easily, 3) we can easily port our system on many embedded systems including PDA and navigator, etc.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.1 s.92
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• pp.1-8
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• 2005

This paper proposes a new type of a dual-band internal antenna for GPS/PCS handsets. The antenna has three monopoles in different lengths, and this structure is referred as a 3-fingers type antenna in this paper. The antenna with low-profile structure is designed to use internal space of handset maximally. The fabrication and the measurement are accomplished by attaching the 3-finger type antenna to the inside of a commercial handset. We obtain gain of 1.97 dBi$\~$0.66 dBi in the GPS band, and -0.92 dBi$\~$1.02 dBi in the PCS band and almost omni-directional patterns at all bands.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.12 s.91
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• pp.1190-1198
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• 2004

In this paper, meander-line planar monopole antenna mounted on PCS/IMT-2000/WLAN handset for SAR reduction is designed. Frequency characteristics and SAR value optimized with various design parameters are analyzed and designed. Designed internal monopole antenna mounted on the handset is simulated. The 1 g and 10 g peak average SARs of internal monopole antenna are 0.656 and 0.387 W/kg respectively. And internal monopole antenna and external monopole antenna attached on the handset are tested. As a result, internal monopole antenna 1 g and 10 g peak average SARs are 0.686 and 0.356 W/kg. And external monopole antenna's results are 1.33 and 0.812 W/kg, respectively. So internal monopole antenna has a about $50\%$ SAR reduction in comparison with external monopole antenna.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.10
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• pp.1189-1195
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• 2007

We design and fabricate, in this parer, a triple band folded monopole antenna for the folder type mobile phone handset that can be served GSM/DCS/USPCS mobile phone system. Antenna structure is modified meander shape which is obtained both extension of antenna physical length for GSM band and same directional multi-currents flowing on the antenna conductor surface for DCS/USPCS band. This antenna has as good performances as high radiation resistance and gain increment, and would be applied to mobile phone handset that is not able to be performed by internal antenna. By measurement, fabricated antenna by the press process shows under VSWR 3:1 at closed folder state and 2:1 at opened folder state over whole GSM/DCS/USPCS band, and has maximum gain as -0.02 dBi for GSM, +0.2 dBi for DCS, +0.78 dBi for USPCS band with almost omnidirectional H-plane radiation pattern.