• Journal of Broadcast Engineering
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• v.18 no.5
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• pp.669-679
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• 2013

This paper proposed a new VLSI (Very Large Scale Integrated Circuit) architecture for stereo matching in real time. We minimized the amount of calculation and the number of memory accesses through analyzing calculation of stereo matching. From this, we proposed a new stereo matching calculating cell and a new hardware architecture by expanding it in parallel, which concurrently calculates cost function for all pixels in a search range. After expanding it, we proposed a new hardware architecture to calculate cost function for 2-dimensional region. The implemented hardware can be operated with minimum 250Mhz clock frequence in FPGA (Field Programmable Gate Array) environment, and has the performance of 805fps in case of the search range of 64 pixels and the image size of $640{\times}480$.

• Proceedings of the KIEE Conference
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• summer
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• pp.1439-1441
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• 2004

ITS 데이터 통신체계는 도로상의 현장설비(차량 검지기. 도로전광표지, 번호인식장치 등)와 센터를 1:1로 직접 접속하는 방식(P2P)으로 구성하고 있다. P2P 데이터 통신은 안정적인 데이터 전송을 유지시켜주지만, 통신비용의 증가 원인이 되고 있다. 따라서. 본 연구는 1:1 유선통신 구성으로 인한 통신비를 줄이기 위해 위성통신을 사용하여 1:N 구성으로 통신비용을 줄이는 방법을 제안하였고. 적용 가능성을 확인하기 위해 국도 43호선 2개소에 대해서 옵셋 안테나. 위성송출장비 등의 위성통신 장비를 설치한 후 데이터를 수집하였다. 적용 주파수 대역은 $(TX)13.75\sim14.50GHz,\;(RX)10.70\sim12.75GHz$이다. 데이터 품질은 기존의 1:1 구성 방식인 유선 전용회선에 의한 데이터(기준치)와 제안한 위성통신의 데이터를 비교하는 과정이며, 이를 통해 위성통신의 현장 적용가능성을 검토하였다.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.8
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• pp.97-103
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• 2014

Signal processing technique of linear frequency modulation-frequency shift keying (LFM-FSK) waveform has been introduced for rear view radars of an automobile. LFM-FSK waveform consists of two sequential stepped frequency waveforms with some frequency offset, and thus, can be used to generate inverse synthetic aperture radar (ISAR) images of rear view target of an automobile. However, ISAR images can often be blurred due to inter-pulse phase errors. To resolve this problem, one-dimensional (1-D) entropies of high resolution range profiles (HRRP) are minimized with the help of particle swarm optimization (PSO). The searching space used in PSO is adaptively adjusted by the use of information on the target's velocity obtained from LFM-FSK waveforms. Simulation results show that the proposed method can generate well-focused ISAR images.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.12
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• pp.197-203
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• 2014

When the lightning current is injected to the ground system of information and communication facilities, analysis of the transient potential rise in the ground system is one of main factors to effectively design the ground system. The performance of grounding systems is normally estimated with the grounding impedance and the transient potential rise which represents the electrical characteristics of the grounding system. The method for calculating the grounding impedance depending on the injection point of the lightning current was proposed. The delta-gap source model was proposed to calculate the grounding impedance in the case that the lightning current is injected to the center of the horizontal ground electrode. A new program which is possible to apply the frequency-dependent soil parameters using the Debye model was developed, because a commercial program for analyzing the performance of the grounding system can not apply to the frequency-dependent soil parameters. The experiment was carried out to confirm the availability of the simulation results with the same condition. Finally, the transient potential rises of a horizontal ground electrode depending on the lightning current waveforms were analyzed by using the results of the grounding impedance which is associated with the frequency-dependent soil parameters.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.11a
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• pp.148-150
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• 2002

In this paper, a 5-coupled BPF with teflon substrate is presented. In general, for less than 1 GHz frequency, the narrow bandwidth as well as the good characteristic in the rejection frequency band could be realized using lumped elements. However, for higher than 1 GHz frequency, the distributed elements such as microstrip lines need to be used for the design of the desired BPF For less than 2 GHz, the FR4 shows good filter characteristic at low cost. However, in the range of 2 GHz ~ 10 GHz, the filters with FR4 show a big difference between simulation and measurement results. Thus, in such a high frequency region, the teflon is more preferred to the FR4. The center frequency (fc) of the proposed filter is 2.3 GHz, the insertin loss (IL) is 1.2 dB, the return loss (RL) is 30 dB, bandwidth (BW) is 100 MHz, and the size is 8.3 cm $\times$ 4.9 cm.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.38 no.4
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• pp.38-44
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• 2001

In this paper, for the microwave level meter based on the FM-CW radar, we analyze the spectrum correlation of beat signals and propose a measurement algorithm using the theory. For industrial applications, level meters must have high precision, which requires a good linearity of VCO. But, in practice, it is very complicated or very expensive to make VCO linear enough to be acceptable in the industrial field. We propose a measurement algorithm using the fact that there exists a peak in the spectrum correlation of beat signals when range difference is sufficiently small. This makes it possible to determine the range difference in a precise manner even using a practical VCO. We present some experimental results to show the validity of this algorithm.

• Journal of the Korean Society for Marine Environment & Energy
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• v.17 no.2
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• pp.146-152
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• 2014

Design procedure of WEC (wave energy converter) using the heaving motion of a floating cylinder-type buoy coupled with LEG (linear electric generator) system is introduced. It is seen that the maximum power can actually be obtained at the optimal conditions ($c_{PTO}=b_T$, ${\omega}={\omega}_N$). Then, based on the developed theory, several design strategies are proposed to further enhance the maximum PTO (power take off), which includes the intentional mismatching with the heave natural frequency, which is 15% higher value than the peak frequency of input velocity spectrum. By using the intentional mismatching strategy, the generated power is actually increased and the corresponding draft as well as the required PTO damping value is significantly reduced, which is a big advantage in manufacturing the WEC with practical LEG (linear electric generator) system.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.106.2-106.2
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• 2013

본 논문은 반도체 및 평판 디스플레이 생산공정에서 가동되고 있는 건식 진공펌프들의 정밀 상태진단 및 예지 보수를 위한 pump monitoring system (PMS)의 제품화에 필요한 프로그램의 개발 내용을 소개한다. 본 연구에서 소개하는 건식 진공펌프들의 정밀 상태진단 및 예지보수기법은 PCT 특허 2 건으로 이미 등록된 내용이며, 본 논문은 이들 기법의 실제 구현에서 직면하는 기술적 문제점과 극복 방안을 제시한다. 본 논문에서는 현재 반도체 공정에 사용되고 있는 건식 진공펌프들로부터 측정하는 다중 상태변수들의 조사 결과를 소개한다. 이들 상태변수 측정치들이 갖는 개략적 특성을 통계적 분포함수로 분석한 결과를 우선 보인다. 특히 펌프 구동모터들의 소비 전류신호는 두 평균값에 대한 분포 즉 두 종의 분포함수를, 그리고 온도, purge gas 유량, 배기구 압력 등은 정상적 평균값에 대한 한나의 분포를 보였다. 따라서 구동모터들의 소비전류의 분포 즉 두 상하 수준('low and high' current level)에 따라 batch data를 구분하는 방법의 개발이 필요하였다. 본 연구에서는 step 함수형 eigenvector를 적용하여 소비전류 신호의 상하수준 천이 영역과 방향을 동시에 인식할 수 있는 기법을 개발 적용하였으며, 3300회의 배출가스 부하에 변화에 대한 천이 영역과 방향을 인식에 하나의 실패도 보이지 않음을 확인하였다. 기존의 측정 상태변수에는 회전기계류의 정밀 상태진단 및 예지보수에 핵심적인 기계진동 측정용 진동센서를 포함하고 있지 않은 기술적 문제점이 발견되었다. 기존 진동센서들의 높은 가격 뿐 아니라 진동센서의 출력신호를 저/중/고역 주파수 대역의 실효치로 환산하는 기술적 한계 때문에 진공펌프 상태진단에 아직 사용하고 있지 않고 있다. 본 연구에서는 진동선서 비용의 저감화 방안뿐 아니라 로터 회전 대역(250Hz 이하 저주파 영역), 베어링 진동 대역(250 Hz~2.5 kHz의 중간 주파수 영역), 그리고 기어 진동 대역(2.5 kHz~10 kHz 주파수 영역)별 실효치를 실 시간 측정할 수 있는 진동측정 모듈의 제품화 모델을 개발하였다. 개발 제품의 성능 뿐 아니라 현장 시험결과를 소개한다. 마지막으로 본 연구팀이 개발한 PCT 특허 2 건에 포함된 건식 진공펌프들의 정밀 상태진단 및 예지보수기법에 대한 현장 시험결과를 간략히 소개한다.

• Journal of Digital Contents Society
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• v.14 no.2
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• pp.191-197
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• 2013

To complete the "anywhere" mobile service there should not be shaded areas. However, it is never economical to deploy BS's (Base Stations) in a low population density area due to the low resource utilization. We propose a design technique to install RS's(Relay Stations) which are cheaper than BS's and find the condition in which the proposed technique is acceptible. The proposed design technique aims to allocate the frequency and time resources to RS's to minimize the transmission rate degradation due to interferences between RS's as well as to maximize the parallelism in transmission. We showed by simulation that the proposed technique achieves cost benefits when the expected traffic is less than 20.32 percent of the total BS capacity. The proposed technique is compatible with the IEEE 802.16j, thus can be extended to multi-hop configuration.

• Journal of Korea Technology Innovation Society
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• v.9 no.4
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• pp.627-653
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• 2006

The purpose of this study lies in understanding how the spectrum assigned for each mobile operator affects the consumers of mobile service. For this purpose, we have observed the change of path coefficient in the structural equation, using control variables. However, the structure of the mobile service market in Korea has become fixed. Considering this tendency and the conclusion of this study, the 'lock-in effect' occurs seriously in the mobile service market in Korea. It can be explained by the fact that CS(Customer Satisfaction) of the cellular subscribers little affects customer loyalty but the market dominance of the cellular service in the actual market has continued for a long time. In this study, we figured out a strong prejudice about call quality, which is caused by spectrum difference among competitors. Cellular subscribers tends to believe that call quality of their cellular service is better than that of PCS. In addition, we found that PCS operators can catch customer's retention by investment into network in order to increase call quality.