• 재활복지공학회논문지
• /
• 제9권2호
• /
• pp.161-168
• /
• 2015

본 논문은 자체 개발한 관성측정장치의 가속도, 각속도, 지자기계 데이터를 이용하여 보행거리를 측정하는 시스템 개발에 관한 것이다. 관성센서들의 오프셋 및 이득 오차를 최소화하기 위하여 9축의 자유도를 갖는 지그를 제작하였으며, 이를 이용하여 캘리브레이션을 수행하였다. 보행거리의 정확한 측정을 위하여, 기울기 하강법을 이용하여 가속도계의 중력성분 제거 및 보행패턴 분석을 통한 드리프트 성분을 제거하였다. 최종적으로 보정된 가속도 데이터의 이중적분을 통하여 보행거리를 측정하였다. 시스템의 성능 평가를 위하여, 실내 직선 10m 직선 보행에 대하여 캘리브레이션 전, 후 오차 개선 비율를 비교하였으며, 간단한 보행에 대해 Vicon과의 비교 실험을 수행하였다. 직선 보행에 대해서는 x, y, z축 각각에 대하여 $31.4{\pm}14.38%$(mean${\pm}$S.D.), $78.64{\pm}10.84%$ 및 $69.71{\pm}26.25%$ 개선이 되었음을 확인하였으며, Vicon과의 비교 실험 결과 x, y, z축 각각에 대하여 0.1m, 0.16m, 0.12m의 오차를 얻을 수 있었다.

• International Journal of Fuzzy Logic and Intelligent Systems
• /
• 제11권4호
• /
• pp.280-285
• /
• 2011

Recently, with the development of service robots and the concept of ubiquitous, the position estimation of mobile objects has received great interest. Some of the localization schemes are introduced, which provide the relative location of the moving objects subjected to accumulated errors. To implement a real time localization system, a new absolute position estimation method for a mobile robot in indoor environment is proposed. Design and implementation of the localization system comes from the usage of active beacon systems (based upon RFID technology). The active beacon system is composed of an RFID receiver and an ultra-sonic transmitter. The RFID receiver gets the synchronization signal from the mobile robot and the ultra-sonic transmitter sends out the traveling signal to be used for measuring the distance. Position of a mobile robot in a three dimensional space can be calculated basically from the distance information from three beacons and the absolute position information of the beacons themselves. In some case, the mobile robot can acquire the ultrasonic signals from only one or two beacons, due to the obstacles located along the moving path. In this paper, a position estimation scheme using fewer than three sensors is developed. Also, the extended Kalman filter algorithm is applied for the improvement of position estimation accuracy of the mobile robot.

• 대한기계학회논문집B
• /
• 제22권4호
• /
• pp.510-519
• /
• 1998

Recently, computer modelling is increasingly used as a design tool, which requires more detailed data for heat transfer coefficients in various regions of the induction motor. But there are little information about those of rotor fan and endring because of difficulty in measuring signals in rotating bodies. In the present studies, the temperature signals were precisely measured with self-developed telemetry system, which had multi-channels and high rotational speed. After some losses were compensated, the heat transfer coefficients of the rotor endring and fan surfaces were measured. Minimum heat transfer region was existed with endcap plate distance and maximum heat transfer was found at some rotor fan width. It was also studied that how the guide plate and endcap inside rib effected on the rotor heat transfer. The higher heat transfer were obtained with decreasing guide plate distance, increasing the number and height of endcap inside rib. The correlation equations of the results were obtained and compared with others. Above results of the heat transfer coefficients can be used as basic data for cooling design of the various kind of motors.

• 한국분무공학회지
• /
• 제9권3호
• /
• pp.22-28
• /
• 2004

This study is concerned about the characteristics of ultrasonic-energy-added W/O type emulsified fuel. The distilled water was mixed with diesel oil by using ultrasonic energy fuel feeding system and then the SMD of sprayed droplets was measured to find out atomization characteristics of emulsified fuel by using the Malvern 2600 system. The capacitance value was measured to verify stability of the same specimen by using the digital LCR meter, EDC1630 additionally. The main results are as follows; 1) The more measuring distance increases between one hole nozzle tip and analyser bearm, the more SMD increases. 2) The more water content increases, the more capacitance value increases depending on the time. Main Parameters of the study are the amount of water content $0{\sim}30%$ by 5% in emulsified fuel, and the measurement distance, $20{\sim}140mm$ by 10mm or 20mm between nozzle tip and analyser beam.

• 대한인간공학회지
• /
• 제22권2호
• /
• pp.15-28
• /
• 2003

The one of the most important factors is the platoon design on developing AH3(Advanced Highway System), as it is related to traffic efficiency and drivers' safety. This study was evaluated that how much speed is comfortable for drivers and how long distance is appropriate for vehicular gap of platoon by measuring drivers' physiology signal and sensibility. A fixed-based AHS simulator was developed by using a real vehicle cockpit and the restructured part of Korean highway for human factors evaluation. The EEG(electroencephalogram), ECG (electrocardiogram) and GSR(Galvanic Skin Response) were measured for obtaining drivers' physiology signal according to the change of speed and gap. The brain wave(${\alpha},\;{\beta},\;{\delta},\;{\theta}$) by EEG, the response of the autonomic nervous system. the sympathetic and parasympathetic nervous system, by ECG, and relax-arousal situation by GSR were analyzed. The SD(Semantic Differential) method was also applied to evaluate drivers' sensibility by 5-grade evaluation scale with 96 adjectives. SSQ(Simulator Sickness Questionnaire) was used to measure the simulator sickness of pre and post driving, two times. As the results, drivers were comfortable with 120km/h speed of platoon and lam to 15m vehicular distance. The results of this study may differ from the adaption of the reality because of many parameters. However, the purpose of this study is show to significant results of the drivers' safety and the acceptability of human factors evaluation.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2009년도 세계 도시지반공학 심포지엄
• /
• pp.1338-1345
• /
• 2009

Although rock excavation is necessary for the effective utilization of urban space, most conventional rock excavation methods, including the blasting method, cause high noise and vibration. Meanwhile, if a high pressure waterjet system is applied to excavate underground spaces in urban areas, the public grievance can be reduced by low noise and vibration. In this study, an abrasive waterjet system is designed and developed to study the influence of various performance parameters such as jet pressure, nozzle traverse speed, stand-off distance, or abrasive feed rate on waterjet excavation performance in laboratory. Using the developed waterjet system, rock drilling characteristics are identified by measuring drilling depths as a function of the jet exposure time. The drilling depth linearly increases with increasing the jet exposure time(under 60sec). Rock cutting characteristics are also obtained with various jet pressures(1600~3200kg/$cm^2$) and nozzle traverse speeds(1.9~14.1mm/s): The cutting depth is nonlinearly related to the jet pressure and traverse speed. Indeed, the cutting depth increases with an increase in the jet pressure and a decrease in the nozzle traverse speed. This trend can be explained by energy transferring/loss mechanism.

• 한국위성정보통신학회논문지
• /
• 제9권2호
• /
• pp.38-44
• /
• 2014

본 논문은 FMCW(Frequency Modulated Continuous Wave) 레이더 레벨 측정기 설계와 시뮬레이션을 통한 성능분석에 대하여 기술한다. 설계된 레벨미터는 FMCW radar를 이용하여 최대 20m 거리를 측정하며, 거리 계산을 위한 비트신호 분석기법으로 FFT(Fast Fourier Transform)와 Zoom-FFT를 적용하였다. 성능 분석을 위해 시뮬레이션을 통하여 두가지 기법을 비교 분석한 결과, 측정오류를 최소화하고 측정의 분해능을 향상시키기 위해서는 Zoom-FFT 기법이 보다 적절한 기법임을 확인하였다. 시뮬레이션은 주파수 분해능과 측정거리 분해능의 최적 값을 얻기 위해 다양한 조건에서 분석하였고, 1.024GHz 주파수 조건에서 2.2mm의 측정 분해능을 확인하였다.

• 사물인터넷융복합논문지
• /
• 제10권4호
• /
• pp.71-76
• /
• 2024

최근 위치기반 서비스의 중요도가 갈수록 늘어나고 있다. 그리고 이와 관련하여 Ultra-Wideband(UWB) 기술이 많은 모바일 단말들과 차량 등에 장착되고 있다. 하지만 일반적인 UWB 기반 측위 시스템의 경우 단순히 두 단말 사이의 거리와 방향을 파악하는 데에 사용되거나, 빌딩이나 공장, 쇼핑몰 같은 곳에 UWB anchor를 미리 설치한 후, 근로자나 고객의 위치를 확인하기 위하여 사용하기도 한다. 본 논문에서는 이러한 기법들과는 다른 방식으로 노드들의 위치를 파악하는 분산 노드 기반 Anchor-less UWB 측위 시스템의 특성에 대해서 분석하였으며, 노드 수의 증가 및 설정한 Ranging 주기에 따라 시스템의 실제 Ranging 주기 및 거리 추정 오차에 대해서 측정하였다. 또한, 본 시스템을 활용한 측위 시스템의 정확도를 실험을 통해 분석하였다. 실험 결과, Anchor를 설치하지 않고, 노드 간의 시동기 작업을 하지 않은 상태에서도 평균 0.32m의 오차를 가지는 것을 확인할 수 있었다.

• 센서학회지
• /
• 제5권2호
• /
• pp.29-36
• /
• 1996

본 논문에서는 전기기기 및 전력설비의 운전 조작중에 발생하는 극저주파 영역(ELF)의 자장을 측정 및 분석 할 수 있는 장치로써 멀티턴 루우프형 센서를 이용한 3차원 자장측정계에 대해 기술한다. 저주파특성의 개선과 왜곡없는 공간자장성분의 측정 등 우수한 성능을 얻기 위해서, 자장측정계를 멀티턴 루우프형 센서와 증폭기, 능동성 적분기로 구성하여 3차원적으로 설계 제작하였다. 교정실험을 통하여 측정계의 고유응답특성을 산출한 결과, 주파수대역은 x, y, z 축 각각 8[Hz]에서 53[kHz] 정도이고, 응답감도는 9.54, 9.21, $10.89[mV/{\mu}T]$이다. 진동성 임펄스전류발생기를 이용한 적용실험으로써 측정계의 신뢰성을 확인하였고, 소형 전등기의 기동시에 발생하는 자장과 측정거리에 따른 정상운전중의 자장특성을 측정 분석한 결과 자장의 세기는 각각 최대 15.8, $8.61[{\mu}T]$이며, 거리가 증가할수록 급격한 감소를 보였다.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2015년도 제46회 하계학술대회
• /
• pp.251-252
• /
• 2015

The designed hybrid generation system (HGS) not only consider the voltage condition of grid connection point but also do reactive power support according to the transmission system operator's directions. The PCS operation plan in HGS should be supported by precise transferred quantity expectation about reactive power because the system has large physical areas and also be interconnected with grid through long transmission system. Therefore, the realistic measuring process about transferred reactive power quantity by utilizing HGS is required to consider additional compensation plan. In this paper, an reactive power transferred capability of HGS with expected parameter is analyzed, and imposed to the simulation process that is performed on EMTDC environment. Basically, grid information and system characteristics were utilized with Jeju island in Korea, and the performance analysis is carried out based on the composed layout in ongoing project.