• Journal of Astronomy and Space Sciences
• /
• 제27권3호
• /
• pp.213-220
• /
• 2010

As an observation instrument of the longest record of tropospheric water vapor, radiosonde data provide upper-air pressure (geopotential height), temperature, humidity and wind. However, the data have some well-known elements related to inaccuracy. In this article, radiosonde precipitable water vapor (PWV) at Sokcho observatory was compared with global positioning system (GPS) PWV during each summertime of year 2007 and 2008 and the biases were calculated. As a result, the mean bias showed negative values regardless of the rainfall occurrence. In addition, on the basis of GPS PWV, the maximum root mean square error (RMSE) was 5.67 mm over the radiosonde PWV.

• 한국음향학회지
• /
• 제19권7호
• /
• pp.77-84
• /
• 2000

도플러 로그용 센서를 이용하여 선박의 속도를 측정하면, 선박의 수평방향 이외의 움직임, 즉 피칭이나 롤링 등에 의한 측정 속도의 부정확성이 문제가 된다. 본 연구에서는 이러한 피칭과 수중이라는 환경요인에 기인하여 다른 속도 측정용 센서들이 가지는 문제점을 극복할 수 있는 야누스형 초음파 트랜스듀서를 개발하였다. 트랜스듀서 개발을 위하여 그 작동 구조를 해석하고 그에 따라 시제품을 제작한 후, 실험적인 성능 평가를 이루었다.

• 한국IT서비스학회지
• /
• 제8권2호
• /
• pp.43-70
• /
• 2009

As software development and maintenance cost increase quickly, information systems managers are more concerned about how to effectively manage software cost. To estimate the software development cost, most public institutes of Korea use the software cost estimation standard established by the government. Unfortunately, the accuracy of the estimation derived from the standard has not been satisfactory in spite of repetitive modifications made to improve it. One of the major reasons for the inaccuracy is that the standard has too small a number of cost adjustment factors to reflect the various characteristics of a software development project. To remedy this problem, we propose new cost adjustment factors which can be incorporated into the standard and are important to enhance the estimation accuracy, based on the analysis of several well-known software estimation models. Furthermore, by applying the proposed model to real world software projects, we show that the proposed model can produce more accurate estimates than the current standard.

• Journal of Information Display
• /
• 제5권3호
• /
• pp.1-7
• /
• 2004

We developed a novel frame interpolation method to interpolate a frame between two successive original frames. Using this method, we are able to apply a double-rate driving method instead of an impulse driving method where a black frame is inserted between two successive original frames. The double-rate driving method enables amelioration of the motion blur of LCDs caused by the characteristics of human vision without reducing the luminosity of the whole screen. The image quality of the double-rate driving method was also found to be better than that of an impulse driving method using our motion picture simulator and an actual panel. Our initial model of our frame interpolation method consists of motion estimation with a maximum matching pixel count estimation function, an area segmentation technique, and motion compensation with variable segmentation threshold. Although salt and pepper noise remained in a portion of an object mainly due to inaccuracy of motion estimation, we verified the validity of our method and the possibility of improvement in hold-type motion blurring.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 2004년도 춘계학술대회 논문집
• /
• pp.47-52
• /
• 2004

Springback comes from the release of residual stress after forming. The control of phenomenon is especially important in the sheet metal forming since there are no other practical methods available to correct the dimensional inaccuracy from springback. Therefore the accurate predication before the die machining has been a long goal in the Held of sheet metal forming. The aim of the present study is to enhance the prediction capability of finite element(FE) analysis for the springback phenomenon. For this purpose FE analysis for V-bending has been carried out with the commercial programs, LS-DYNA. The FE analysis results have been validated through the comparison of experimental. The experimental results measured directly by the strain gauge have given the confidence to FEA.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
• /
• pp.775-778
• /
• 1996

In this research, the robustness of a seam tracking for the automatic welding system is studied. The laser displacement sensor is used as a seam finder. X-Y moving table drived by ac servo motor controls the position and velocity of the torch-and-sensor part. However, dc servo motor is used to control the position and velocity of the torch. The sensor locates ahead of torch to preview the weld line, and brings about the inaccuracy on the torch tracking. To enhance the robustness on this system against the influence of disturbances and model uncertainty, H$\_$.inf./ control is applied to the angular motion of torch. The simulation shows that the tracking accuracy improved significantly. Also, experimental results give a good performance of H$\_$.inf./ control strategy to the automatic seam tracking system for the welding.

• 제어로봇시스템학회논문지
• /
• 제14권8호
• /
• pp.774-778
• /
• 2008

The inaccuracy of inertial sensors used in low cost IMU's limits the usage to ARS, at best. Sensor fusion technologies are widely used to overcome this problem. GPS is the most popular secondary sensor, but GPS alone cannot fully compensate the IMU errors in the initial alignment process and rectilinear flights. This paper presents a new concept of aiding the low cost IMU with the sun line of sight vector. The simulation and experimental results in this paper proves that aiding of INS/GPS with the sun line of sight vector increases the observability and improves accuracy remarkably.

• Journal of Welding and Joining
• /
• 제8권2호
• /
• pp.58-69
• /
• 1990

In conventional arc welding, position error of the weld torch with respect to the weld seam and variation of groove dimension are induced by inaccurate fitup and fixturing. In this study, a vision system has been developed to recognize and compensate the position error and dimensional inaccuracy. The system uses a structured laser light illuminated on the weld groove and perceived by a C.C.D camera. A new algorithm to detect the edge of the reflected laser light is introduced for real time processing. The developed system was applied to arbitarary weld paths with various types of joint in arc welding process. The experimental results show that the proposed system can detect the weld groove parameters within good accuracy and yield good tracking performance.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2008년도 춘계 학술발표회 초청강연 및 논문집
• /
• pp.1036-1041
• /
• 2008

In order to analysis the reason of sliding failure in embankment slope under construction in soft soil area, a model section located in Gimhae Region in Gyeongsangnam-Do, where the sliding failure had been occurred during embankment works in soft soil area, had been selected. This area had been firstly treated with the Pack Drain Method, and additional embankment works of 9.7 meters out of total 14 meters in thickness had been under construction. The results of analysis showed that the reason of sliding failure were overspeed in embankment construction and the overestimation of design factors in calculating strength of each layer of embankment and poor management and inaccuracy reading of measurement devices.

• 한국의상디자인학회지
• /
• 제11권3호
• /
• pp.17-25
• /
• 2009

The purpose of this study is to help understanding of abstract patterns and to play a guideline's role in the development of designs and the prediction of trends for present and future fashion designers and textile designers. The summary of this study's results is like followings. Formative characteristics of abstract pattern in 2000's fashion are Impromptu, Anti-mechanism, Superimposing, Disorder. First, Impromptu is rebounce against uniformity, mechanism, man-created beauty Second, Anti-mechanism represents unfinishing, unbalance, inaccuracy and relates with each traditional of nation or ethnic group. Third, Presupposing transparency Superimposing offsets each patterns. So Their images are ambiguity, ununiformity, unequality, incompletion, uncertainty and so on. Fourth, Disorder breaks and ignores physical balance, rule, order and so on. These images represent uncertainty, freedom, naturality. From this result, I can interpret that these images are representing of humanism reacting about uniformity, mechanism, man-created beauty, completeness of modernism since the Industrial Revolution.