• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2010.09a
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• pp.129-133
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• 2010

본 논문은 차량의 공회전시 불완전연소로 인한 일산화탄소의 배출량이 최대인 점에 착안하여 일반 네비게이션에서 제공하는 최단거리 모드로 주행했을 시와 '막힘없는 길 안내를 제공' 한다는 최신 공간정보기술인 실시간교통정보서비스를 적용했을 시의 공회전시간 및 일산화탄소 배출량을 비교 평가하여, 실시간교통정보서비스의 일산화탄소 저감효과를 추정해보기 위해 진행되었다. 대구시내의 교통정체구역인 수성구청에서 성서초등학교에 이르는 약 12km의 구간을 선정하여 2주간 동일구간을 요일별 시간대별로 주행함으로써 최단거리 안내서비스 주행시와 실시간교통정보서비스를 적용한 경로주행시의 공회전시간을 기록하고 환경부에서 제공하는 연료별 배출계수와 평균속도에 따른 일산화탄소 배출계수를 이용하여 일산화탄소 배출량을 산정하였으며, 측정결과 공회전시간이 약 28%, 일산화탄소 배출량은 약 57%의 감축효과를 보임을 확인하였다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.11
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• pp.1019-1025
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• 2004

The X-band 10${\times}$10 waveguide slot array antenna for SAR is designed, fabricated and measured. The array antenna is designed using the equivalent circuit model based on the field distribution of the dominant mode, TE$\sub$10/, and EM simulation. The method to decide optimum angle of the centered inclined slot(coupling slot) and the optimum of offset of the longitudinal slot(radiating slot) is provided. The designed antenna structure is EM simulated and fabricated. The measured return loss bandwidth is 180 MHz at 9.15 GHz , the side lobe level is below -25 dB, HPBW is about 9$^{\circ}$, and the gain is 25.5 dB. These results are similar to the simulation data.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.05a
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• pp.141-144
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• 2009

An injector plays an important role in the process of an efficient combustion in liquid-rocket engines (LRE). This paper is focused on the injection performance of a small LRE-injector by employing the spray characteristic parameters made up of the velocity, Sauter mean diameter, and turbulence intensity. An experimental investigation is carried out with the aid of a dual-mode phase Doppler anemometry (DPDA) according to the injection pressure variation and along transverse axis, spatially. The Weber number and Reynolds number are used to characterize the atomization and turbulence nature of injector spray.

• KEPCO Journal on Electric Power and Energy
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• v.4 no.2
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• pp.55-61
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• 2018

본 연구는 시각 동기 위상 측정 정보를 이용하여 전력계통에 나타나는 여러 가지 동요 현상을 검출하기 위한 기초 연구로써, 시계열 데이터 분석 분야로 분류된다. 제시한 방법은 비선형 동특성에 해석 기반으로 접근하여 전력계통에 나타날 수 있는 여러 동요 현상을 범용적으로 검출해 낼 수 있다. 비선형 동요 현상의 신호적 패턴을 수학적으로 기본 순시치 파형으로부터 피크치 샘플링을 통해 전개하여 계통 요소간 간섭으로 인한 원하지 않는 진동 모드를 검출하고자 한다. 계통의 변화로 진동 모드가 나타날 때, 2차원 평면에 실효치로 환산한 시계열 전압 데이터와 선형화된 플로퀘트 상수(Floquet multiplier)를 맵핑하여 도시하고, 정상상태 지점으로부터 거리를 계산하여 최대 리아프노프 지수 계산을 통해 계통이 불안정하게 되는 시간을 시계열 데이터 분석으로 추정하는 것이 본 방법의 핵심이다. 이러한 접근으로 제시한 비선형 동요 검출 알고리즘을 적용하여 디지털 필터 적용 또는 주파수 영역 해석과 같은 오프라인 Study와 달리 온라인으로 신속하게 계통의 현재 상태를 알 수 있게 된다.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.10
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• pp.71-79
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• 2008

This paper analyzed the voltage induction phenomena on the telecommunication lines by electromagnetic coupling from high-speed A.C. electrified railway. The induced common mode voltages and the induced differential mode voltage on the telecommunication line was measured by notified standard method in the regulation of Korea. The test lines consist of 2 separated lines of 20 m and 300 m in influence distance each for comparison, with 2km inducing length. The analysis is made on the induced voltages from the different influence distances and the different earthing points, and also on the waveform and spectrum distributions. It is proved that the induction is arisen so good and the measured values are fair enough against noise such as the earth voltage differencing, and the current measuring scheme is also rightful.

• Korean Journal of Optics and Photonics
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• v.4 no.4
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• pp.434-441
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• 1993

Focusing geometry dependence of output Stokes energy in single pass methane Raman shifter is investigated. The experimental result shows that the threshold energy decreases as confocal parameter increases. This result can be explained by gain suppression caused by Stokes - anti-Stokes coupling. In this paper, we give simple analysis for the focusing geometry dependence of Stokes - anti-Stokes coupling and present the criterion of confocal parameter to reduce the gain suppression. Focusing geometry dependence of stimulated Brillouin scattering is measured and the result is in good agreement with theoretical prediction.

• The Journal of the Acoustical Society of Korea
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• v.22 no.7
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• pp.554-561
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• 2003

Results of the numerical simulation and experimental data analysis for identification of mode cutoff frequency and estimation of sound speed of seabed from the spectrum of acoustic signal received at fixed source-receiver range are presented. Model simulations for Pekeris waveguide show that the frequency-dependent propagation loss and interference pattern are closely related to mode cutoff frequencies and it could be possible to the identify them from the changes of interference pattern. The concept considered at numerical simulations is applied to signals acquired at sea test. Cutoff frequency and sound speed of seabed are estimated from the interference pattern of measured signal. Propagation loss predicted using the estimated sound speed of seabed as model input parameter shows similar estimation result compared to propagation loss derived from measured data.

• Journal of Climate Change Research
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• v.3 no.4
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• pp.235-243
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• 2012

Mobile sources are one of the most significant contributors to the inventory of greenhouse gas (GHG). The administration in Korea has set a goal of cutting GHG emissions of vehicles by 34.3% compared to Business As Usual (BAU) by 2020. To achieve this goal, GHG emission standards for vehicles have been applied since 2012, and now light-duty trucks are under consideration to be included to the vehicle types that will be regulated in the new version of GHG emission standards. Therefore, this study focuses on analyzing characteristics of exhaust GHGs (CO2, CH4, and N2O) emissions of diesel light-duty trucks according to their various driving modes. GHGs emissions of diesel light-duty trucks reduced in inverse proportion to the speed of the vehicles. GHGs emissions from the combined mode were 8% and 14% lower than those from the CVS- 75 and NEDC modes, respectively.

• Proceedings of the Korea Information Processing Society Conference
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• 2016.10a
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• pp.886-887
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• 2016

최근 우리사회는 다양한 형태의 여가활동 및 생활체육에 대한 국민적 욕구와 열망과 더불어서, IoT기술발전 및 시장확대에 힘입어 다양한 스마트 자전거 제품이 등장하고 있다. 그러나 기존 제품의 경우 속도계 장치에 의한 주행기록을 분석할 수 없고, 스마트폰 앱의 경우에는 정확한 데이터 측정이 불가능하다. 이러한 문제점을 해결하기 위하여, 본 논문에서 개발한 스마트 자전거는 마그네틱 센서를 이용하여 거리, 속도, 시간 등을 측정/분석하고, 라이딩 정보를 어플리케이션에 저장하여 사용자가 라이딩 정보를 언제든 살펴볼 수 있다. 또한, 라이딩 속도에 따라서 LED의 색상이 변경되어 익스트림 라이딩 모드 및 LED제어, 스마트 자물쇠 기능 등을 제공한다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.3
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• pp.296-303
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• 2014

In this paper, we propose an algorithm to visualize radio wave environment based on the measured Received Signal Strength Indication( RSSI) and 3D geographic information. We estimate the source position using the circumcenter of the triangle and visualize the radio wave environment using the empirical propagation models. A mode seeking algorithm(mean-shift clustering) is used to seek the peak points and the center of gravity is utilized to reduce the estimation errors. Our approach finds its applications in the radio wave monitoring systems for the efficient utilization of radio resources.