• Proceedings of the Optical Society of Korea Conference
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• 2003.02a
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• pp.156-157
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• 2003

The wavelength converter is considered to be a key element of future dense WDM optical networks. It enables wavelength reuse and resolves contention problem. Moreover, the tunability of the wavelength converter enhance the flexibility of network systems by facilitating reconfigurable dynamic wavelength routing. In order to achieve optically tunable wavelength conversion, we recently proposed and experimentally demonstrated wavelength conversion and tuning based on cascaded sum and difference frequency generation in a Ti：PPLN channel waveguide. (omitted)

• Journal of the Korea Institute of Military Science and Technology
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• v.16 no.6
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• pp.833-840
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• 2013

A radar altimeter which measures the distance using radio wave developed by domestic technology has been applied to various missiles. It is used also for calculating the error of integrated navigation technique. There are a couple of methods to reduce the error but in this paper, we proposed to utilize existing C-band radar altimeter main body with frequency conversion. We designed and manufactured the frequency converter and Ku-band antenna to accomplish this goal. From the test results of products' function and performance, we could expect the possibility of applying this method to enhance the missiles' integrated performance.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2019.06a
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• pp.118-119
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• 2019

본 논문에서는 비디오 제작 및 유통의 활성화에 따라 필요성이 높아지고 있는 장면 전환을 검출하는 방법을 제안한다. 유통 과정에서 해상도 변환, 자막 삽입, 압축, 영상 반전 등의 다양한 변형이 추가되더라도 동일하게 장면 전환을 검출해야 하므로 전처리 과정과 SIFT를 이용한 특징 추출, 변형을 고려한 매칭 방법을 이용하여 프레임 간의 매칭률을 계산한다. 또한 매칭률의 임계값을 기준으로 장면 전환 여부를 판단한다. 원본 비디오에서의 특징을 가지고 다양한 변형이 가해진 비디오에서의 특징과 매칭률을 계산하여 유효성을 판단한다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.7
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• pp.785-790
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• 2008

In this paper, a new balun is proposed. This proposed balun has a DGS(Defected Ground Structure) pattern on the ground plane. The transmission-line is transformed by microstrip-to-slotline transition. DGS pattern on the ground plane and transition of the lines can be easily made a property of the balun. Resonance frequency of the DGS leads to operating frequency of the balun. Also the transition produces $180^{\circ}$ out-of-phase between two output ports without additional transmission line. In this paper, a new balun with VPDGS(Vertically Periodic Defected Ground Structure) effectively lower the operating frequency. To validate the proposed design method, the new balun is designed, fabricated and measured at 2 GHz.

• The Journal of the Korea Contents Association
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• v.9 no.12
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• pp.86-93
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• 2009

In this paper, we propose a method that generates a sketch likely to be drawn by a human from a real image(a computer generated image or a photo image). The method can create human friendly images with pen strokes by using image processing techniques such as spatial filters. In order to create the human friendly image, first, we made the tiny unnecessary contours. Second, we made the second image by inverting the first image and performed a processing similar to the first processing. Last, we subtracted the second image from the first image and added a hatch to it. The sequence of processing enables us to generate a human friendly image with line shading, likely to be sketched by water pen compared to the past method(pencil hatching and sketch effects). Also the proposed method can represent the sketch effects more effectively with applying different hatch to the shading area of a input image.

• Journal of Korea Multimedia Society
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• v.12 no.7
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• pp.947-952
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• 2009

In this paper, we propose a method of generating color sketch images using the DIP operator. In the proposed method, an input RGB color image is first transformed into an HSV color image. A sketch image of the V component image is then extracted by applying the DIP operator to the V component image, which is the brightness component of the input image. For the visual convenience, the extracted sketch image of the V component image is next inverted and contrast-stretched. The S component image is also enhanced to deepen the color of output sketch image while maintaining its color. Finally, the V and S component images along with the original H component image are transformed into an output RGB color sketch image. Experimental results show that the proposed method yields output color sketch images similar to hand-drawn sketch pictures whose colors are the same as those of input color images.

• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.515-516
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• 2006

본 논문은 풍속이 변화하는 상황에서 풍력 발전 시스템의 동작을 실시간으로 모의할 수 있는 시뮬레이터의 구성과 실험 결과를 제시한다. 본 논문에서 제시하고자하는 풍력 발전 시스템 시뮬레이터는 실시간 시뮬레이터인 RTDS(Real Time Digital Simulator)와 11kW의 AC 서보 시스템을 포함하는 전동기-발전기 실험 장치(MG set, Motor-Generator Set)로 구현되었다. RTDS는 풍속 모델과 블레이드, 터빈, 발전기를 포함하는 풍력발전 시스템 모델을 실시간으로 모의하며 MG-set은 실시간으로 모의된 풍력 발전 시스템의 물리적 상태를 구현한다. 풍력 발전 시스템 모델의 동작점 궤적과 최대출력점추종(Maximum Power Point Tracking)제어에 의한 풍력 발전 시스템 시뮬레이터의 운전 결과의 제시를 통해 시뮬레이터의 유용성을 검증하였다. 본 논문에서 제시된 시뮬레이터는 상용 실시간 시뮬레이터를 이용하여 간단한 소프트웨어의 수정을 통해 다양한 모델의 풍력 반전 시스템을 모의할 수 있으며 다양한 실험 조건에서 과도상태 및 정상상태 특성 실험이 가능하므로 풍력 발전 시스템의 발전기 특성 평가, 전력 변환 장치의 성능 시험 등에 활용이 가능하다.

• Electronics and Telecommunications Trends
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• v.27 no.1
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• pp.1-18
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• 2012

미래 사회는 나노기술(NT)을 바탕으로 IT-ET-BT 기술이 융합된 유비쿼터스 사회로 진화하고 있으며, 미래 산업 사회로의 전환을 위해서는 성능개선이 아닌 성능한계 돌파의 패러다임 전환이 가능한 임계성능의 나노 소재/신소자의 개발이 절실히 요구되고 있다. 또한 차세대 단말기는 휴대성의 편리함, 융복합화/다기능화, 인간 친화형이 요구되고, flexible/stretchable/bendable한 형태로 발전하고 있는 상황이다. 나노 피에조트로닉스(nanopiezotronics) 기술은 역학적 에너지를 전기적 에너지로 변환하는 나노 발전 소자(nanogenerator)의 원리를 기반으로 하며 나노선, 나노벨트와 같은 1차원적 나노구조 소재의 압전성과 반전도성이 결합된 특성을 이용한 신기능의 미래 IT 융합 나노 전자/에너지 소자를 구현하는 기술로서 미래 유망 기술로 부각되고 있다. 현재 기술 수준은 압전 전계 효과 트랜지스터, 압전-다이오드, 압전 센서, 압전 나노 발전 소자 등과 같은 prototype 소자를 제작하는 수준에 머무르고 있으나 향후 초고감도 압전 센서, 자가발전 MEMS/NEMS 및 나노 시스템, 스마트 웨어러블 시스템, 건강 모니터링 시스템, 인체 삽입형 소자, portable 및 투명 유연 전자소자 등의 다양한 미래 융합 나노 소자 및 시스템에 광범위한 활용이 가능하며, 향후 신기능의 소자/부품/시스템 창출을 위한 기술로 자리매김할 것으로 전망된다. 본고에서는 압전 나노선, 나노튜브, 나노섬유 등의 1차원적 나노구조체 기반의 nanopiezotronics 기술과 최근의 연구결과들을 소개한다.

• Transactions of the Korean Society of Automotive Engineers
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• v.19 no.3
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• pp.113-121
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• 2011

Rollover accident is one of the serious traffic accident and rollover accident takes high portion of all accident. The most common type of rollover is a tripped rollover which occupy 95% of all type of single-vehicle rollover. Tripped rollover occurs when a vehicle leaves normal road way and tripped by loose gravel, soil of fixed object such as guard rail, curbs and ditches. And the rest of the type of rollover is un-tripped rollover. An un-tripped rollovers that occurs during high-speed collision avoidance maneuvers. In this paper, presents the explanation of the un-tripped rollover test method and procedure, additionally this paper deals with various occurrence in the un-tripped test such as occurring excessive tire camber in the un-tripped test, tire side-wall contact with road surface and roll oscillation. And this paper analyzes the analysis of the roll rate amplitude in specific frequency through the FFT (Fast Fourier Transform) and the roll angle at the steering reverse timing which is the Fishhook test roll rate feedback time. Finally, this paper analyzes the relations between the estimated steady state roll gain and rollover stability.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.2
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• pp.113-122
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• 2016

In this paper, we suggest a approach which comprises fast Fourier transform inversion by wavelet noise attenuation. It represents an inverse filtering by adopting a factor into the Wiener filtering, and the optimal factor is chosen to minimize the overall mean squared error. in order to apply the Wiener filter, we have to compute the power spectrum of original image from the corrupted figure. Since the Wiener filtering contains the inverse filtering process, it expands the noise when the blurring filter is not invertible. To remove the large noises, the best is to remove the noise using wavelet threshold. Wavelet noise attenuation steps are consisted of inverse filtering and noise reduction by Wavelet functions. experimental results have not outperformed the other methods over the overall restoration performance.