• Proceedings of the KIEE Conference
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• 2001.11c
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• pp.107-110
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• 2001

Recently, there are lots of concerning on robot agent system working for itself with the trends of the research of bio-mimetic system and intelligent robot. In this paper, a virtual 3D interface system is proposed based on Internet for remote controlling and monitoring of mobile robot. The proposed system is constructed as manager-agent model. A worker can order the robot agent move to a new position by clicking the destination on virtual space of 3D graphic interface in manager. Then the robot agent move to the position automatically with avoiding collision by using range finding and autonomous control algorithm. The proposed robot agent system lets us control the mobile robot remotely located more conveniently.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.123.1-123
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• 2001

For Autonomous navigation of the mobile robots, the robots' capability to recognize 3D environment is necessary. In this paper, an on-line 3D map building method for autonomous mobile robots is proposed. To get range data on the environment, we use an sensor system which is composed of a structured light and a CCD camera based on optimal triangulation. The structured laser is projected as a horizontal strip on the scene. The sensor system can rotate $\pm$ $30{\Circ}$ with a goniometer. Scanning the system, we get the laser strip image for the environments and update planes composing the environment by some image processing steps. From the laser strip on the captured image, we find a center point of each column, and make line segments through blobbing these center poings. Then, the planes of the environments are updated. These steps are done on-line in scanning phase. With the proposed method, we can efficiently get a 3D map about the structured environment.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.123.5-123
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• 2001

For autonomous navigation of the mobile robots, the robots' capability to recognize 3D environment is necessary. In this paper, an on-line 3D map building method for autonomous mobile robots is proposed. To get range data on the environment, we use a sensor system which is composed of a structured light and a CCD camera based on optimal triangulation. The structured laser is projected as a horizontal strip on the scene. The sensor system can rotate$\pm$30$^{\circ}$ with a goniometer. Scanning the system, we get the laser strip image for the environments and update planes composing the environment by some image processing steps. From the laser strip on the captured image, we find a center point of each column, and make line segments through blobbing these center points. Then, the planes of the environments are updated. These steps are done on-line in scanning phase. With the proposed method, we can efficiently get a 3D map about the structured environment.

• Journal of Korea Multimedia Society
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• v.11 no.6
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• pp.816-827
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• 2008

In this paper, two-stage pipelined floating-point arithmetic unit (FP-AU) is designed. The FP-AU processor supports seventeen operations to apply 3D graphics processor and has area-efficient and low-latency architecture that makes use of modified dual-path computation scheme, new normalization circuit, and modified compound adder based on flagged prefix adder. The FP-AU has about 4-ns delay time at logic synthesis condition using $0.18{\mu}m$ CMOS standard cell library and consists of about 5,930 gates. Because it has 250 MFLOPS execution rate and supports saturated arithmetic including a number of graphics-oriented operations, it is applicable to mobile 3D graphics accelerator efficiently.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.1095-1098
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• 2009

Stereoscopic (3D) content must be viewable in a variety of visual environments, from 3D theaters to 3D mobile displays. However, the depth sensations provided by 3D media are affected by the viewing conditions, such as screen size, viewing distance, and other factors. This user experience (UX) aspect makes it difficult to create multi-purpose 3D content. This paper describes two study cases in which the authors have focused on the UX and the multi-purposing of 3D content. The first case is an evaluation of 3D image quality on a mobile display. The second case is a trial development of a scalable 3D conversion process.

• The KIPS Transactions:PartD
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• v.10D no.3
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• pp.439-446
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• 2003

A crucial limitation in environments where data is broadcast to very large client populations is the low bandwidth available for clients to communicate with servers. Many advanced applications are developed in mobile computing environments, but conventional concurrency controls are not suitable because of the low bandwidth of wireless network. In this paper, we propose a new optimistic concurrency control protocol for mobile transactions. In this protocol, mobile read-only transactions can be completed locally at the clients without additional communication, only mobile update transactions are sent to the server for global validation. Our protocol reduces unnecessary aborts occurred in the previous study using only conflict information. In addition to, our algorithm can detect and resolve non-serializable execution using by data table maintained in a server.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.5
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• pp.568-575
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• 2011

In this paper, we propose a small broadband antenna for mobile device. The proposed antenna consists of a printed rectangular monopole antenna and a parastic element connected to ground using narrow meander line and it is designed on a FR-4 substrate that has a thickness of 0.8 mm and a dielectric constant of 4.4. The FR-4 substrate's size is 50 mm${\times}$90 mm comparable to the real mobile device. The fabricated antenna's size is 12.5 mm${\times}$10.5 mm${\times}$0.8 mm and the measurement shows -10 dB return loss bandwidth of 2,200~6,000 MHz and gains of 2.86~4.01 dBi. Accordingly, the proposed antenna can support mobile device for WiBro(2,300~2,380 MHz), WLAN(IEEE 802.11b/g/n: 2,400~2,480 MHz, IEEE 802.11a: 5,150~5,825 MHz), and mobile WiMAX(IEEE 802.16e : 2,500~2,690 MHz, 3,400~3,600 MHz) service bands.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.28 no.3
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• pp.18-25
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• 2005

QFD is a system fur designing a product or service base on customer demand and involving all members of the producer or supplier organization. In this paper, we will introduce application of QFD as a tool for the mobile phone battery R&D.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.40 no.3
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• pp.1-9
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• 2003

In this paper, we designed a highly suppressed sidelobe ladder type RF SAW bandpass filter based on 1-port resonator, for 800 MHz mobile communication system. In order to get the highest device characteristics, we optimized some important parameters such as the electrode thickness, electrode lambda weghting of the reflectors, and static capacitance ratio. Furthermore, we fabricated the Tx and Rx. filter using optimized parameters. Implemented filters can be used in 800 MHz mobile communication system and external impedance matching circuits are not needed. RF filter was fabricated on 36$^{\circ}$LiTaO$_3$ substrates with Al-Cu (W 3 %)and mounted 3.8mm$\times$3.8mm$\times$1.5mm SMD package. Developed filters has 2.3 dB insertion loss in the 25 MHz pass-band, 33MHz with 3-dB insertion loss, stop-band rejection of 30 dB, passband ripple is less than 0.5 The power durability of the filters measured about 3.5W and the maximum temperature variation within -2$0^{\circ}C$~8$0^{\circ}C$ was 0.09 dB/$^{\circ}C$ of 3-dB insertion loss.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.3
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• pp.51-57
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• 2010

A dual-mode direct conversion receiver is developed in $0.13\;{\mu}m$ RF CMOS process for IEEE 802.11n based wireless LAN and IEEE 802.16e based mobile WiMAX application. The RF receiver covers the frequency band between 2.3 and 2.7 GHz. Three-step gain control is realized in LNA by using current steering technique. Current bleeding technique is applied to the down-conversion mixer in order to lower the flicker noise. A frequency divide-by-2 circuit is included in the receiver for LO I/Q differential signal generation. The receiver consumes 56 mA at 1.4 V supply voltage including all LO buffers. Measured results show a power gain of 32 dB, a noise figure of 4.8 dB, a output $P_{1dB}$ of +6 dBm over the entire band.