• 대한공간정보학회지
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• 제10권2호
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• pp.87-95
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• 2002

실시간 동적(Real Time Kinematic) GPS는 실시간으로 높은 정밀도의 위치결정을 가능케 해준다. 만약 미지정수를 구하기 위하여 정수해를 사용한다면 수 mm의 정확도를 얻을 수 있고, 실 수해를 얻는다면 수십 cm 의 정확도를 얻을수 있다. 본 연구에서는 통일 측점에 대해 기존의 재래식 측량기법(Total Station), 정적(Static) 상대측위 GPS기법과 현장 Calibration에 의한 실시간 동적(Real Time Kinematic) GPS기법에 의해 측량을 수행하여 각 기법별 측정의 정확도 등을 비교 분석하여 현장 Calibration에 의한 실시간 동적 (Real Time Kinematic) GPS기법의 정확도를 분석고자 한다. 국소지역에서 기존의 실시간 동적(Real Time Kinematic) GPS방식을 보완한 현장 Calibration에 의한 실시간 동적(Real Time Kinematic) GPS 측량을 수행한 결과, 미지정수해의 고정해를 얻지 못하는 경우를 제외하고는 모두 6cm 이하의 오차가 나타났고, Control Point의 측점수를 3개와 4개로 변화시켜 실시간 동적(Real Time Kinematic) GPS 측량을 수행한 결과 두 측정치의 차이는 최대 3cm로 나타났다. 최종적으로 국소지역에서도 현장 Calibration에 의한 실시간 동적(Real Time Kinematic) GPS기법이 사용가능함을 알 수 있었다.

• The Journal of Korean Physical Therapy
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• 제16권3호
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• pp.161-175
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• 2004

The purpose of this study was to determine the effect of HPAFO(Hinged Plastic Ankle Foot orthosis) and SPAFO(Solid Plastic Ankle Foot Orthosis) on standing balance and step moving in hemiplegia patients. Twenty hemiplegic patients were either inpatient or outpatient at the Rehabilitation medicine, MokPo J General Hospital and JeonJu J Medical Center from July 15, 2002 to September 15, 2002. Patients were able to ambulate independently for at least 10 meters and to stand independently for at least 10 minutes with balance measurement tool. The static balance and dynamic activity measurement was determined by SAKAI active balancer(Japan) with wearing HPAFO and wearing SPAFO. The static balance and dynamic activity analysis was analyzed by independent t-test. The results were as follows: 1. There were no significant difference in body weight bearing percent between wearing HPAFO and wearing SPAFO(p>0.05). 2. There were significant difference in whole path length between wearing HPAFO and wearing SPAFO(p<0.05). 3. There were significant difference in Effective Value Area between wearing HPAFO and wearing SPAFO(p>0.001). 4. There were significant difference in repeated functional time between wearing HPAFO and wearing SPAFO(p>0.001). 5. There were significant difference in cadence between wearing HPAFO and wearing SPAFO(p>0.001). The result of this study showed that wearing HPAFO and wearing SPAFO gave fair amount of improvement to static standing balance and dynamic movement ability of hemiplegic patients. The comparison result showed significant differences in between HPAFO and SPAHFO. The result of this study had a general limitation due to the restricted number of cases. The future study needs more detailed research and comparison with various variance between these two orthoses.

• 대한기계학회논문집A
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• 제26권3호
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• pp.537-543
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• 2002

This paper examines a new in-process measurement system for the measurement of micro-defects on the surfaces of brittle materials by using the AFM (Atomic Force Microscopy). A new AFM scanning stage that can also perform nano-scale bending of the sample was developed by adding a bending unit to a commercially available AFM scanner. The bending unit consists of a PZT actuator and sample holder, and can perform static and cyclic three-point bending. The true bending displacement of the bending unit is approximately 1.8mm when 80 volts are applied to the PZT actuator. The frequency response of the bending unit and the stress on the sample were also analyzed, both theoretically and experimentally. Potential surface defects of the sample were successfully detected by this measurement system. It was confirmed that the number of micro-defects on a scratched surface increases when the surface is subjected to a cyclic bending load.

• International Journal of Aeronautical and Space Sciences
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• 제5권1호
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• pp.46-56
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• 2004

The verification and improvement of the measurement uncertainty have beenperformed in the altitude test facility for small gas turbine engines, which was built atthe Korea Aerospace Research Institute (KARI) in October 1999. This test is performedwith a single spool turbojet engine at several flight conditions. This paper discussesthe evaluation and validation process for the measurement uncertainty improvements usedin the altitude test facility. The evaluation process, defined as tests before the facilitymodification, shows that the major contnbutors to the measurement uncertainty are theflow meter discharge coefficient, the inlet static and total pressures, the cell pressureand the fuel flow rate. The measurement uncertainty is focused on the primary parametersof the engine performance such as airflow rate, thrust and specific fuel consumption (SFC).The validation process, defined as tests after the facility modification, shows that themeasurement uncertainty, in seal level condition, is tmproved to the acceptable level throughthe facility modification. In altitude test conditions, the measurement uncertainties arenot improved as much as the uncertainty in sea level condition.

• Journal of Electrical Engineering and Technology
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• 제1권2호
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• pp.161-169
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• 2006

Load representation has a significant impact on power system analysis and control results. In this paper, composite load models are developed based on on-line measurement data from a practical power system. Three types of static-dynamic load models are derived: general ZIP-induction motor model, Exponential-induction motor model and Z-induction motor model. For the dynamic induction motor model, two different third-order induction motor models are studied. The performances in modeling real and reactive power behaviors by composite load models are compared with other dynamic load models in terms of relative mismatch error. In addition, numerical consideration of ill-conditioned parameters is addressed based on trajectory sensitivity. Numerical studies indicate that the developed composite load models can accurately capture the dynamic behaviors of loads during disturbance.

• 한국추진공학회지
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• 제14권1호
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• pp.48-55
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• 2010

본 논문에서는 엔진고공환경 시험설비의 엔진 입구 덕트에서 측정한 전압력과 정압력 및 전온도를 통해 실시간으로 공기유량을 계산하고, 압력프로파일을 이용하여 경계층 레이크를 장착하지 않았을 경우에도 공기유량을 예측할 수 있는 방법을 기술하였다. 또한, 엔진입구배관에 걸친 덕트 연결부를 통한압력손실을 예측하고, 이를 통해 공기유량을 보정함으로써, 고공환경시험설비에서의 공기유량측정의 신뢰도를 향상시키고 설비유지측면에서의 운용성을 보고자 하였다.

• Journal of Electrical Engineering and Technology
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• 제3권4호
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• pp.451-459
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• 2008

Accurate load modeling is essential for power system static and dynamic analysis. By the nature of the problem of parameter estimation for power system load modeling using actual measurements, multiple local optimal solutions may exist and local methods can be trapped in a local optimal solution giving possibly poor performance. In this paper, Trust-Tech, a novel methodology for global optimization, is applied to tackle the multiple local optimal solutions issue in measurement-based power system load modeling. Multiple sets of parameter values of a composite load model are obtained using Trust-Tech in a deterministic manner. Numerical studies indicate that Trust-Tech along with conventional local methods can be successfully applied to power system load model parameter estimation in measurement-based approaches.

• Journal of the Optical Society of Korea
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• 제19권6호
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• pp.575-585
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• 2015

Magnetic field in magnetic bearings is the physical medium to realize magnetic levitation, the distribution of the magnetic field determines the operating performance of magnetic bearings. In this paper, a thin-slice Fiber Bragg Grating-Giant Magnetostrictive Material magnetic sensor used for the air gap of magnetic bearings was proposed and tested in the condition of dynamic magnetic field. The static property of the sensor was calibrated and a polynomial curve was fitted to describe the performance of the sensor. Measurement of dynamic magnetic field with different frequencies in magnetic bearings was implemented. Comparing with the finite element simulations, the results showed the DC component of the magnetic field was detected by the sensor and error was less than 5.87%.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 추계학술대회 논문집
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• pp.228-233
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• 2004

A derailment coefficient of railway vehicle is as one of important element that estimate running safety. Derailment coefficient is ratio of lateral load/vertical load happens in contact point between wheel and rail. Lateral load increases, dangerous of derailment can rise. There are ground and vehicle to measurement method of these derailment coefficient. Method of ground is simple, but when vehicles passes data of a point, there is shortcoming that acquire locally. Curved surface style wheel shape that use so far among vehicle method in this research wishes to be not but describe about static load test of wheel-set for derailment coefficient measurement that have plane plate shape that manufacture separate way and correction result etc. to test.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 A
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• pp.193-195
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• 2003

This paper presents an approach to estimate the power transmission line parameter by phasor measurement units(PMUs), which are synchronized to 1 pps signal of GPS. Existing approaches to estimate power transmission line parameter, are mainly off-line ones, based on faults or switching events on other neighboring lines. In this paper, to obtain static and dynamic properties of power transmission line parameter in service, the prototype of pmu-based Transmission Line Parameter Monitoring System (TLPMS) is proposed. Also, an technique to estimate parameters of transmission line described as 2-port network model and the soundness of estimated parameters are addressed.