• 대한조선학회논문집
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• 제42권2호
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• pp.73-79
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• 2005

The characteristics of a tilt sensor utilizing the resistance change of an electrolyte associated with inclination is investigated, and a dynamic compensation modeling is proposed to make the real-time measurement of the absolute slope possible even with sporadically dynamic motion. Although the proposed system is small, economical and accurate for quasi-steady slope measurement, since it contains a freesurface the evolution of the liquid surface that has no direct relation to the real slope must be excluded for any rapid rotations or translations. For various artificial motions the response of the sensor is analyzed and simplified modeling equations are proposed.

• 한국군사과학기술학회지
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• 제8권3호
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• pp.56-63
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• 2005

The radome boresight error degrades the microwave seeker ability and the missile guidance performance. It increases the miss distance, also. This paper propose a method of radome boresight error measurement and compensation. The compensation method consist of radome analysis and radome compensation. In the radome analysis stage, we can know that the electromagnetic characteristics distorted by radome. In the compensation stage, the look-up table is built and used for compensation. The test uses a FMS(Flight motion simulator) and adjusts the FMS setup error for more accuracy. The result shows that not using an elaborate radome measurement equipment, the radome boresight error is well compensated easily.

• Journal of the Optical Society of Korea
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• 제10권3호
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• pp.112-117
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• 2006

We experimentally investigated the transmission characteristics of 400 Gbit/s (10 Gbit/s ${\times}$ 40 channels) WDM signals with 100 GHz channel spacing over 323 km of installed NZ_DSF. The installed fiber has optical properties of 0.28 dB/km attenuation, 4.3 ps/nm/km dispersion, $0.083ps/nm^2/km$ dispersion slope and less than $0.05ps/km^{1/2}$ PMD coefficient. In this experiment, two cases of dispersion compensation schemes, the lumped type and the distributed type, were compared. The results implied that the distributed type dispersion compensation in which dispersion compensation devices are inserted at the end of the each span showed better transmission performance than the lumped one in which dispersion compensation devices are located at the transmitter and receiver sites. From the analysis of the experimental results, we verified that different transmission performance comes from the power penalty induced by XPM in the distributed scheme is lower than the lumped scheme case.

• 대한전기학회논문지
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• 제43권6호
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• pp.991-1000
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• 1994

To control nonlinear systems adaptively, we improve learning speed of neural networks and present a novel control algorithm characterized by compensation of control inputs. In an error-backpropagation algorithm for tranining multilayer neural networks(MLNN's) the effect of the slope of activation functions on learning performance is investigated and the learning speed of neural networks is improved by auto-adjusting the slope of activation functions. The control system is composed of two MLNN's, one for control and the other for identification, with the weights initialized by off-line training. The control algoritm is modified by a control strategy which compensates the control error induced by the indentification error. Computer simulations show that the proposed control algorithm is efficient in controlling a nonlinear system with abruptly changing parameters.

• 전기학회논문지
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• 제58권4호
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• pp.867-872
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• 2009

Peak expiratory flow rate(PEF) is one of the most important diagnostic parameters in spirometry. PEF occurs in a very short duration during the forced expiratory maneuver, which could lead to measurement error due to non-ideal dynamic characteristic of the transducer. In such case the initial slope of the flow rate signal determines the accuracy of the measured PEF. The present study considered this initial slope as a parameter to compensate PEF. The 26 standard flow rate signals recommended by the American Thoracic Society(ATS) were flown through the air flow transducer followed by simultaneous measurements of PEF and maximum transducer output$(N_{PEF})$. $N_{PEF}$-PEF satisfied a quadratic equation in general, however, two signals (ATS #2 and #26) having large initial slopes deviated from the fitting equation to a significant degree. The relative error was found to be in a linear relationship with the initial slope, thus, $N_{PEF}$ was appropriately compensated to provide accurate PEF with mean relative error less than only 1%. The 99% confidence interval of the mean relative error was less than a half of the error limit of 5% recommended by ATS. Therefore, PEF can be very accurately determined by compensating the transducer output based on the initial slope, which should be a useful technique for air flow transducer calibration.

• 디지털콘텐츠학회 논문지
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• 제18권4호
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• pp.777-785
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• 2017

실세계에서 텍스트가 포함 된 장면은 텍스트를 추출하고 인식하여 많은 정보를 얻을 수 있으므로, 장면의 텍스트 영역을 추출하고 인식하는 기술들은 꾸준히 발전하고 있다. 장면에서 텍스트 영역을 추출하는 기술은 크게 텍스쳐를 기반으로 하는 방법과 연결요소방법, 그리고 이 둘을 적절히 혼합하는 방법들로 구분 할 수 있다. 텍스처를 기반으로 하는 방법은 영상의 색상, 명도 등의 정보를 이용하여 텍스트가 다른 요소와는 다른 값을 갖는다는 것을 기반으로 한다. 연결 요소 방법은 장면의 각 화소마다 인접해 있는 유사 화소를 연결 요소로 만들어 기하학적인 특성을 이용하여 판별한다. 본 논문에서는 텍스트 영역 추출의 정확도를 높이기 위해 영상의 기울기를 검출하고 보정한 후 에지를 적응적으로 변경하는 방법을 제안한다. 제안 방법은 영상의 기울기를 보정한 후 텍스트가 포함 된 정확한 영역만 추출하기 때문에 MSER보다 15%, EEMSER보다 10% 더 정확하게 영역을 얻었다.

• 한국자동차공학회논문집
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• 제22권3호
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• pp.114-122
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• 2014

Sensor fusion is the one of the main research topics. It offers the highly reliable estimation of vehicle movement by processing and mixing several sensor outputs. But unfortunately, every sensor has drift which degrades the performance of sensor. It means a single degraded sensor output may affect whole sensor fusion system. Drift in most research is ideally assumed to be zero because it's usually a nonlinear model and has sample variation. Plus, it's very difficult for the acceleration to separate drift from the output signal since it contains many contributors such as vehicle acceleration, slope angle, pitch angle, surface condition and so on. In this paper, modified spline interpolation is introduced as a dynamic temperature compensation method covering sample variation. Using the last known output and the first initial output is suggested to build and update compensation factor. When the system has more compensation data, the system will have better performance of compensated output because of the regression compensation model. The performance of the dynamic temperature compensation system is evaluated by measuring offset drift between with and without the compensation.

• Journal of the Optical Society of Korea
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• 제18권3호
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• pp.207-216
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• 2014

In this work, we report detailed numerical analysis of the near-elliptic core index-guiding triangular-lattice and square-lattice photonic crystal fiber (PCFs); where we numerically characterize the birefringence, single mode, cut-off behavior and group velocity dispersion and effective area properties. By varying geometry and examining the modal field profile we find that for the same relative values of $d/{\Lambda}$, triangular-lattice PCFs show higher birefringence whereas the square-lattice PCFs show a wider range of single-mode operation. Square-lattice PCF was found to be endlessly single-mode for higher air-filling fraction ($d/{\Lambda}$). Dispersion comparison between the two structures reveal that we need smaller lengths of triangular-lattice PCF for dispersion compensation whereas PCFs with square-lattice with nearer relative dispersion slope (RDS) can better compensate the broadband dispersion. Square-lattice PCFs show zero dispersion wavelength (ZDW) red-shifted, making it preferable for mid-IR supercontinuum generation (SCG) with highly non-linear chalcogenide material. Square-lattice PCFs show higher dispersion slope that leads to compression of the broadband, thus accumulating more power in the pulse. On the other hand, triangular-lattice PCF with flat dispersion profile can generate broader SCG. Square-lattice PCF with low Group Velocity Dispersion (GVD) at the anomalous dispersion corresponds to higher dispersion length ($L_D$) and higher degree of solitonic interaction. The effective area of square-lattice PCF is always greater than its triangular-lattice counterpart making it better suited for high power applications. We have also performed a comparison of the dispersion properties of between the symmetric-core and asymmetric-core triangular-lattice PCF. While we need smaller length of symmetric-core PCF for dispersion compensation, broadband dispersion compensation can be performed with asymmetric-core PCF. Mid-Infrared (IR) SCG can be better performed with asymmetric core PCF with compressed and high power pulse, while wider range of SCG can be performed with symmetric core PCF. Thus, this study will be extremely useful for designing/realizing fiber towards a custom application around these characteristics.

• International Journal of Precision Engineering and Manufacturing
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• 제9권3호
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• pp.27-32
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• 2008

This paper describes a contact atomic force microscope (AFM) that can be used for high-speed precision measurements of microstructured surfaces. The AFM is composed of an air-bearing X stage, an air-bearing spindle with the axis of rotation in the Z direction, and an AFM probe unit. The traversing distance and maximum speed of the X stage are 300 mm and 400 mm/s, respectively. The spindle has the ability to hold a sample in a vacuum chuck with a maximum diameter of 130 mm and has a maximum rotation speed of 300 rpm. The bandwidth of the AFM probe unit in an open loop control circuit is more than 40 kHz. To achieve precision measurements of microstructured surfaces with slopes, a scanning strategy combining constant height measurements with a slope compensation technique is proposed. In this scanning strategy, the Z direction PZT actuator of the AFM probe unit is employed to compensate for the slope of the sample surface while the microstructures are scanned by the AFM probe at a constant height. The precision of such a scanning strategy is demonstrated by obtaining profile measurements of a microstructure surface at a series of scanning speeds ranging from 0.1 to 20.0 mm/s.

• 디지털콘텐츠학회 논문지
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• 제17권5호
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• pp.441-448
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• 2016

본 논문에서는 문자열과 배경이 혼합된 장면에서 영상을 분할하여 기울기를 추출하고 보정하는 방법을 제안한다. 제안된 방법은 모폴로지를 이용하여 전처리를 하고 캐니 연산자를 이용하여 경계선을 검출한다. 그리고 경계선이 검출된 영상을 분할하여 경계선이 포함되어 있지 않는 영역은 배제하고 경계선이 포함되어 있는 영역만을 이용하여 여러 방향의 기울기에 따른 투영 히스토그램을 생성한다. 이를 이용하여 각 영역의 최대 경계선 집중도를 갖는 기울기를 구하고 장면의 기울기를 보정한다. 문자열과 배경이 혼합된 장면의 기울기 검출에서 제안된 방법은 경계선이 없는 무의미한 부분을 배제하기 때문에 기존의 방법보다 0.7% 더 좋은 결과를 얻을 수 있었다.