• Proceedings of the KIEE Conference
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• 2007.11a
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• pp.138-139
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• 2007

The use of conventional Twyman and Fizeau interferometers inevitably fails in testing high precision optics because of errors always existing in reference elements producing the reference wavefront. Therefore it is necessary to apply to this task the interferometers of a radically new type, which are able to produce perfect reference wavefront with the help of light diffraction by a small obstacle or pinhole. In this paper new theoretical approaches and schematics of point diffraction interferometers are considered in detail with paying attention to constructive reliability. Such interferometers do not use reference optical surfaces and readily provide adequate estimation of errors and aberrations value of 0.01 wavelengths.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.33 no.4
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• pp.231-244
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• 2015

The accuracy of reference point of VLBI antenna is mandatory to perform collocation of different space geodetic techniques. In this study, we evaluated the optimal methods for the 3D circle fitting to enhance the accuracy of the reference point of VLBI antenna. Two kinds of methodologies for the orthonormal coordinate system with translation of planar observation point and the unitary coordinate transforamation were suggested and their fitting accuracies were evaluated where the orthogonal distance was calculated by residual between observation point and fitting model and the recursive calculation was performed to improve the accuracy of 3D circle fitting. Finally, we found that the methodology for the unitary coordinate transformation is highly appropriate to determine the optimal equation for azimuth-axis and elevation-axis of VLBI antenna. Therefore, the reference point of VLBI antenna with high accuracy can be determined by the intersection of the above two axises (azimuth-axis and elevation-axis). This result is expected to be utilized for a variety of researches for connection between VLBI observation results and the national control point.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.11
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• pp.1777-1784
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• 2001

This paper provides d simplified engineering J estimation method fur semi-e1liptical surface cracked plates in tension, based on the reference stress approach. Note that the essential element of the reference stress approach is the plastic limit lead in the definition of the reference stress. However, for surface cracks, the definition of the limit load is ambiguous ("local" or "global"limit lead), and thus the most relevant limit load (and thus reference stress) for the J estimation should be determined. In the present work, such limit load solution is found by comparing reference stress bated J results with those from extensive 3-D finite element analyses. Validation of the proposed equation against FF J results based on tactual experimental tensile data of a 304 stainless steel shows excellent agreements not only far the J values at the deepest point but also for those at an arbitrary paint along the crack front, including at the surface point. Thus the present results provide a good engineering tool for elastic-plastic fracture analyses of surface cracked plates in tension.

• Korean Journal of Remote Sensing
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• v.23 no.5
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• pp.483-491
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• 2007

One of the major obstacles to classify and validate Land Cover maps is the high cost of acquiring reference data. In case of inaccessible areas such as North Korea, the high resolution satellite imagery may be used for reference data. The objective of this paper is to investigate the possibility of utilizing QuickBird high resolution imagery of North Korea that can be obtained from Google Earth data via internet for reference data of land cover classification. Monthly MODIS NDVI data of nine months from the summer of 2004 were classified into L=54 cluster using ISODATA algorithm, and these L clusters were assigned to 7 classes - coniferous forest, deciduous forest, mixed forest, paddy field, dry field, water, and built-up areas - by careful use of reference data obtained through visual interpretation of the high resolution imagery. The overall accuracy and Kappa index were 85.98% and 0.82, respectively, which represents about 10% point increase of classification accuracy than our previous study based on GCP point data around North Korea. Thus we can conclude that Google Earth may be used to substitute the traditional reference data collection on the site where the accessibility is severely limited.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 1998.11a
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• pp.248-251
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• 1998

본 연구에서는, GPS 기준점(Optimal reference point)을 기준으로 한 DGPS(Differential Global Positioning System)와, 준 기준점(Sut-optimal reference point)을 기준으로 한 DGPS 시스템을 구현하였다. 이러한 2가지 DGPS 시스템으로부터 얻은 위치를 분석 평가하고, 그 결과를 나타냈다. 실험 결과, 준기준점을 기준으로 하는 DGPS 시스템은, 기존의 DGPS 기준국을 사용하지 않더라도 정밀 위치 측정이 가능함을 나타내었다.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.2
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• pp.175-184
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• 2010

The purpose of this study is to develop a method for estimating the non-point pollutant delivery load of each reference flow(flows of dry, low, normal, abundant and flood seasons) with combination of BASINS/HSPF. The effectiveness of this method is evaluated by applying it to the watershed of Dongbok stream. The flow, BOD and T-P reliability indices(RI) of the BASINS/HSPF for the watershed of Dongbok stream are 1.59, 1.41, 1.28, respectively, and thus the similarity between measured and estimated values is high. The non-point pollutant load delivery ratios of BOD and T-P for the flows of dry, low and normal seasons, which are estimated by such constructed BASINS/HSPF, are 0.36 and 1.09, 0.82 and 2.19, 6.02 and 16.90, respectively, as compared with daily average of non-point loads for a year. These results show that the non-point pollutant delivery load should be estimated and applied for each reference flow, and in this case the method for estimating the non-point pollutant delivery load of each reference flow can be useful.

• The Journal of Korean Society for Radiation Therapy
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• v.18 no.2
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• pp.119-125
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• 2006

Purpose: To measure the dose for dose optimization at the reference point (A, B) and the critical organ with multi Purpose brachytherapy phantom (MPBP). For this wort the MPBP was custom made, and designed to reconstruct the treatment applicator using multi function applicator (MFA) in the same way as the treatment of patient. Materials and Methods: Dose measurements were made at the reference points (A, B) and the bladder with thermoluminescence dosimeter (TLD) for four patients with tandem and ovoid of uterine cervix cancer using the phantom. In Phantom, Total 20 times of the measurements were made with 5 times a patient. Results: The results of TLD measurements in MPBP phantom showed the relative error ranging from -3.2% to 3.8% at A point, and -1.4% to 4% at B point and 1.3% to 7.15% at the bladder of reference point. Conclusion: The reproducibility of dose measurement under the same condition as the treatment could be achieved using the custom-made MFA in phantom and the dose at the reference point (A, B) and bladder could be analyzed accurately. The measured dose acquired in MPBP can apply for the dose optimization.

• Journal of the Korean Society of Costume
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• v.54 no.6
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• pp.1-12
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• 2004

Price is one of the most important components of marketing mix. For consumers, price is an always-existing cue and definite evaluation criteria. However, information on price is meaningful only when it is perceived. Sources of price perception can be the actual retail price at the selling point, the internal reference price expected by consumers for a certain clothing product, and the external reference price advertised by marketer such as the price before mark-down. The purpose of this study was to investigate the influence of internal reference price on consumers' purchasing process of clothing products. A questionnaire including clothing stimuli was developed in order to assess consumers' internal reference price level. Usable data from 680 adult female urban residents were used for data analysis. Results indicated that consumers with relatively lower internal reference price tend to react low-price focused external reference price and use discount stores and unit price promotions. Consumers with relatively higher internal reference price advertisement are likely to have higher level of education, tend to infer price information to higher quality or prestige of products, and purchase clothing with regular retail price or coupons.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.40 no.6
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• pp.95-105
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• 2003

A novel reference point detection method is proposed by exploiting tile gradient probabilistic model that captures the curvature information of fingerprint. The detection of reference point is accomplished through searching and locating the points of occurrence of the most evenly distributed gradient in a probabilistic sense. The uniformly distributed gradient texture represents either the core point itself or those of similar points that can be used to establish the rigid reference from which to map the features for recognition. Key benefits are reductions in preprocessing and consistency of locating the same points as the reference points even when processing arch type fingerprints. Moreover, the new feature extraction method is proposed by improving the existing feature extraction using filterbank method. Experimental results indicate the superiority of tile proposed scheme in terms of computational time in feature extraction and verification rate in various noisy environments. In particular, the proposed gradient probabilistic model achieved 49% improvement under ambient noise, 39.2% under brightness noise and 15.7% under a salt and pepper noise environment, respectively, in FAR for the arch type fingerprints. Moreover, a reduction of 0.07sec in reference point detection time of the GPM is shown possible compared to using the leading the poincare index method and a reduction of 0.06sec in code extraction time of the new filterbank mettled is shown possible compared to using the leading the existing filterbank method.

• Journal of the Korean Society of Clothing and Textiles
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• v.28 no.3_4
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• pp.452-459
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• 2004

The purpose of this study was to evaluate the effect of reference fabric for the tactile sensation of worsted fabrics. As specimens, 32 worsted fabrics for spring/fall suits were selected. A series of subjective evaluation for roughness, harshness, coarseness, smoothness, warmth, bulkiness and softness were performed with 20 trained panels. The panels were selected by the test of consistency and trained for 3 weeks to enhance the reproducibility and consistency. Subjective evaluation was performed using 9 points Semantic Differential Scales with and without reference fabric. Results showed that the sensations were very similar between the results for the test of with or without reference. However the standard deviations of ratings for the with-reference were much less than that of without-reference which means the use of reference fabric can reduce the subjective error or can reduce the number of panels to test.