• Proceedings of the KIPE Conference
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• 2008.06a
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• pp.52-54
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• 2008

간단한 회로구조의 소형 LED 백라이트 제어기의 구현을 위하여 2.5W LED 4개를 각 섹터로 구분지어서 섹터별로 제어를 하는데 목적을 두었다. LED의 전류를 제어하기 위한 스위칭 구동회로 부분을 설계, 구현하고 스위칭을 구동하기 위한 PWM(Pulse Width Modulation)을 마이크로컨트롤러를 이용하여 제어하였다. 섹터제어 회로 부분을 구현하기 위하여 저가의 8비트 마이크로컨트롤러인 PIC16C73B를 사용하였다. 또한, RS-232 통신을 이용하여 각 섹터의 LED 제어 및 휘도를 제어하였다. 이러한 구성을 바탕으로 제어기를 제작 및 실험을 하였으며, 본 논문을 통하여 실험의 타당성을 증명하도록 한다.

• 한국정보통신설비학회:학술대회논문집
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• 2003.08a
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• pp.29-32
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• 2003

본 논문에서는 CDMA 이동통신 망에서 기존의 전통적인 섹터 분할 방식의 섹터간 traffic 불균형 현상에 따른 채널 자원의 비효율적 운용의 문제점 원인을 분석하고, 그 원인을 해소하기 위해 설계 고안된 스마트 섹터 시스템 수동형 모델의 소개, 설치 기법 그리고 이를 기지국에 적용하여 셀 내의 채널 자원 활용 효율이 개선된 결과를 소개하고자 한다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.10a
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• pp.195-196
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• 2016

In the maritime mobile radiocommunication service, AIS(Automatic Identification System) devices are most widely using for the exchange of ship's navigational information. The AIS time slot usage increases due to increasing number of ships installed with AIS, and thus the reception rate of AIS data decrease. In order to mitigate this problem, international organizations recommend a sectorised receiving technique using directional antenna. This paper analyzed the sectorised receiving effectiveness of AIS data using Yaga antenna.

• Journal of Advanced Navigation Technology
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• v.14 no.4
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• pp.489-494
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• 2010

According to the recent increase in air traffic more efficient air traffic control automation is required. Aeronautical traffic environment is different from the common traffic environment since it exist controller for control of aircraft And controller have to control jurisdiction hand-off by manual when aircraft move to the other sector. This paper proposes the automatic control jurisdiction hand-off algorithm for efficient air traffic flow management. It is sector distinction algorithm that aircraft move sector to the other sector it recognized sector and then give permission to authorized controller. As a simulation result, so unlilke simply manual control sector hand-off of existing algorithm. we confirmed that proposed algorithm in this paper can do air traffic control more efficiently by performing automatic aircraft. control sector hand-off.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.12
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• pp.2816-2822
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• 2014

In this paper, a wideband loop antenna for UWB applications is studied. The structure of the proposed wideband loop antenna is a circular loop antenna with appended circular sectors to obtain an ultra-wideband characteristic. The circular sectors are used instead of conventional triangular sectors to match with the 50 ohm feed line. Optimal design parameters are obtained by analyzing the effects of the gap between the circular sectors and the radius of the circular loop on the input reflection coefficient and gain characteristics. The optimized wideband loop antenna is fabricated on an FR4 substrate with a dimension of 41 mm by 41 mm. Experiment results show that the proposed antenna has a frequency band of 3.1-11.0 GHz for a VSWR < 2.25, which assures the operation in the UWB band. Measured gain ranges 1.3-5.3 dBi in the UWB band.

• Journal of Advanced Navigation Technology
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• v.25 no.5
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• pp.384-389
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• 2021

An optimal ground station (GS) antenna pattern design method for network-based UAV command and control communication systems considering complexity and performance is presented. The GS antenna consists of multiple side sectors and one upward sector. The antenna gain for each vertical/horizontal angle of the GS antenna according to the change of antenna design parameters such as the number of sectors, horizontal and vertical beam-width, and tilt-angle is modeled, and the effect of the parameter changes on the signal-to-noise ratio (SNR) distribution in the virtual three-dimensional space is analyzed. It is observed that the tilt-angle of the side sectors has the greatest effect on the performance, and the longer the distance between GSs, the higher the maximum altitude and the smaller the number of side sectors, the tilt-angle should be lower. In addition, it is observed that the wider vertical beam-width of the side sector is advantageous in maximizing the lowest SNR, but narrow vertical beam-width is advantageous in maximizing the average SNR.

• Journal of the Institute of Convergence Signal Processing
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• v.9 no.1
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• pp.24-30
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• 2008

In this paper we analyze the performance of an adaptive sector cell system, which is adopted to maintain the traffic balance between sectors and to utilize the cell resources effectively, using the data collected from real channel environments. In the data measurements, we transmitted the QPSK modulated signal with carrier frequency of 1.95GHz and received the signals using the 8x4 array antenna equipped on the top of buildings in the urban area. We analyzed the angular distribution and the delay spread of a user signal and analyzed angular distribution of mobile users in a cell using the collected data. Also, we propose the vector channel modeling using the estimated pdf(probability distribution function) of the analyzing results. Through the proposed channel modeling the improvement of the call blocking rate was analyzed when using the adaptive sector cell system, and computer simulations show that the call blocking rate of the adaptive sector cell system was much lower than that of the fixed sector cell system. Additionally, it shows that the call blocking rate increases severely in the fixed sector cell system while the difference of the call blocking rate was smaller in the adaptive sector cell system, as the user density of the spatial distribution increases.

• Journal of Technology Innovation
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• v.18 no.2
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• pp.175-219
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• 2010

Since diversification can be a necessary means for company's survival and the conservation of its success, hundreds of studies have been done by three schools of industrial economics, strategic management, and Neo-Schumpeterian economics for over 30 years. However, any school has not presented a model comprehensively explaining diversification' success or failure. The study tried to suggest a theoretical framework integrating findings came from three schools. The framework considers both firm's technological capabilities and sector-specific characteristics as well as reflects a Neo-Schumpeterian view emphasizing technological aspects. The goal of the study is finding major reasons of success and failure during company's diversification through studying three diversification cases of Samsung. Our findings show that the diversification toward TFT-LCD was easier and more successful than the diversification toward microprocessor because DRAM is more similar to TFT-LCD than microprocessor. Samsung also tended to build only the types of capabilities which were originated from capabilities accumulated in DRAM business. Our findings give firm's strategists a lesson that they can increase the probability of success in diversification, if only they should simultaneously consider a new sector's characteristics, a firm's technological capabilities accumulated in old sectors, and the availability of old capabilities for being applied to a new sector.

• Journal of Korean Ophthalmic Optics Society
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• v.13 no.4
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• pp.75-81
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• 2008

Purpose: To develop a solar concentrator having the reflecting surface with the 2m class diameter. Methods: In order to make the reflecting surface for the solar concentrator, the shape of the reflecting surface sector is required. So, first, we induced the formula that can produce this shape. After that, using Delphi 6.0 language, we developed a program which uses this formula and produces the shape and the numerical data of the reflecting surface sector with the input variables such as the external diameter of the reflecting mirror, the reflecting mirror's radius of curvature at the paraxial range, the number of reflecting mirror sector, the size of the center hole of the reflecting mirror, and the interval of the output data. Results: This program, which was developed to produce the shape and the numerical data of the reflecting surface sector, enables us to see the shape of sector on the monitor and to save the numerical data files for the shape of sector. As a result, the user of this program can easily access the numerical data of the reflecting surface sector. Conclusions: Developing the program which produce the reflecting surface sector used to make the reflecting surface of the solar concentrator, we could succeed in making the prototype products by applying it to the development of the real solar concentrator with the diameter of the 2m class.

• The Transactions of the Korean Institute of Power Electronics
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• v.7 no.2
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• pp.137-148
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• 2002

Direct Torque Control(DTC) is considered to be an useful control scheme of high performance induction motor drives because the scheme provides a quick torque response without requiring the complex field-orientation block and inner current regulation loop. Among a few drawbacks of the conventional DTC scheme, large current harmonics due to flux drooping phenomenon in a low speed range may be the major difficulty In order to remove the difficulty, a fuzzy variable switching sector scheme and its real-time implementation algorithm are proposed in this paper. A DSP based control board is designed for the Induction motor drives with the DTC scheme including the fuzzy switching sector algorithm. Simulation and experimental results show the effectiveness of the proposed scheme.