• 한국정보통신학회논문지
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• 제21권11호
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• pp.2191-2198
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• 2017

군 무기체계의 성능을 점검하기 위해 사용되는 정밀측정장비는 수명주기 동안 측정신뢰도 유지를 위해 주기적으로 교정된다. 기존의 교정주기 관련 연구들은 장비의 샘플 크기와 특성을 고려하여 측정신뢰도 모델을 결정할 것을 제안하고 있으나, 다양한 정밀측정장비의 정비 데이터에 동일한 특성 분포를 가정하고 단일 모델을 적용하는 것은 적합하지 않을 수 있다. 본 논문에서는 정밀측정장비의 수명주기 동안 욕조 곡선의 특성을 가정하여 측정신뢰도 모델들로부터 추정된 교정주기 가운데 F-검정과 성능지수 평가를 통해 정비 데이터에 가장 적합한 교정주기가 선택되도록 제안하였다. 제안한 방법을 다양한 장비에 적용한 결과 교정주기 동안 장비의 신뢰도가 유지됨을 확인하였다.

• 정보화연구
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• 제10권2호
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• pp.169-180
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• 2013

합동작전에 참여하는 부대가 효과적으로 임무를 수행하기 위해서는 조직, 시스템, 장비, 교리 절차 등 전 영역(물리 정보 인지 사회)에서의 상호운용성이 우선적으로 달성되어야 한다. 기존의 상호운용성 평가모델들을 분석해보면 하드웨어 중심의 평가에서 시스템, 조직, 작전 등으로 평가 범위가 확장되었으며, 이러한 과정에서 많은 모델들은 전투발전요소를 평가항목에 포함시켰다. 그러나 대부분의 모델들은 전투발전요소의 일부만을 평가항목으로 적용하고 있어 전투발전요소 전체에 대한 상호운용성 평가가 제한되고, 모델을 효과적으로 적용하기 위한 프로세스의 구체화와 평가결과에 대한 객관성을 보장하기 위한 측정기준 개발 등 추가적인 연구가 요구되는 상태이다. 본 논문에서는 이러한 제한사항을 보완하기 위해 전투발전요소 전체를 평가항목으로 적용하는 '전투발전요소 중심의 상호운용성 평가모델'을 제안한다. 제안된 모델은 능력개념을 도입하였고, 전투발전요소 전체를 적용하여 평가대상의 상호운용성 수준을 보다 총체적으로 비교 평가할 수 있다. 또한 이 모델은 각 전투발전요소의 상호운용성 속성 중에서 합동성과 관련된 속성을 선별 및 적용하여 합동작전에 참여하는 부대의 합동성 수준까지 비교 평가할 수 있는 장점을 가지고 있다.

• Smart Structures and Systems
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• 제30권3호
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• pp.287-301
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• 2022

The machine-vision based structural displacement measurement methods are widely used due to its flexible deployment and non-contact measurement characteristics. The accuracy of vision measurement is directly related to the image resolution. In the field of computer vision, super-resolution reconstruction is an emerging method to improve image resolution. Particularly, the deep-learning based image super-resolution methods have shown great potential for improving image resolution and thus the machine-vision based measurement. In this article, we firstly review the latest progress of several deep learning based super-resolution models, together with the public benchmark datasets and the performance evaluation index. Secondly, we construct a binocular visual measurement platform to measure the distances of the adjacent corners on a chessboard that is universally used as a target when measuring the structure displacement via machine-vision based approaches. And then, several typical deep learning based super resolution algorithms are employed to improve the visual measurement performance. Experimental results show that super-resolution reconstruction technology can improve the accuracy of distance measurement of adjacent corners. According to the experimental results, one can find that the measurement accuracy improvement of the super resolution algorithms is not consistent with the existing quantitative performance evaluation index. Lastly, the current challenges and future trends of super resolution algorithms for visual measurement applications are pointed out.

• International Journal of Concrete Structures and Materials
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• 제3권1호
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• pp.57-61
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• 2009

The present work deals with the prediction, through models and experimental evaluation, of the bending strength of roller compacted concrete (RCC) for pavement applications. This concrete was manufactured using low cement proportioning (150 to $250\;kg/m^3$). The characterization of hardened RCC was carried out by experimental measurements of bending strengths. The predictions of these characteristics were achieved using empirical models. Comparison, of the values found in experiments with those empirically obtained, was made in order to choose and to propose the adapted and the most reliable models of prediction. The study showed that the bending strengths of the RCC mixture, experimentally found, can be also identified by models.

• 국제초고층학회논문집
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• 제2권2호
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• pp.105-113
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• 2013

Recent studies proved turbulent flow properties in high-rise building models differ from those in low-rise building models by comparing turbulent statistics. Although it is important to understand the flow characteristics within and above high-rise building models in the study of urban environment, it is still unknown and under investigation. For this reason, we performed wind tunnel experiment using Particle Image Velocimetry (PIV) to investigate and identify the turbulent flow properties and characteristic flow patterns in high-rise building models. In particular, we focus on instantaneous flow field near the canopy and extracted flow field when homogeneous flow field were observed. As a result, six characteristic flow patterns were identified and the relationship between these flow patterns and turbulent organized structure were shown.

• Journal of Positioning, Navigation, and Timing
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• 제10권4호
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• pp.371-377
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• 2021

This research proposes the best combination of tropospheric delay models for Korean Positioning System (KPS). The overall results are based on real observation data of Japanese Quasi-Zenith satellite system (QZSS), whose constellation is similar to the proposed constellation of KPS. The tropospheric delay models are constructed as the combinations of three types of zenith path delay (ZPD) models and four types of mapping functions (MFs). Two sets of International GNSS Service (IGS) stations with the same receiver are considered. Comparison of observation residuals reveals that the ZPD models are more influential to the measurement model rather than MFs, and that the best tropospheric delay model is the combination of GPT3 with 5 degrees grid and Vienna Mapping Function 1 (VMF1). While the bias of observation residual depends on the receivers, it still remains to be further analyzed.

• 대한치과교정학회지
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• 제45권2호
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• pp.82-88
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• 2015

Objective: The aim of this study was to evaluate the reliability of measurements obtained after the superimposition of three-dimensional (3D) digital models by comparing them with those obtained from lateral cephalometric radiographs and photocopies of plaster models for the evaluation of upper molar distalization. Methods: Data were collected from plaster models and lateral cephalometric radiographs of 20 Class II patients whose maxillary first molars were distalized with an intraoral distalizer. The posterior movements of the maxillary first molars were evaluated using lateral cephalometric radiographs (group CP), photocopies of plaster models (group PH), and digitized 3D models (group TD). Additionally, distalization and expansion of the other teeth and the degrees of molar rotation were measured in group PH and group TD and compared between the two groups. Results: No significant difference was observed regarding the amount of molar distalization among the three groups. A comparison of the aforementioned parameters between group PH and group TD did not reveal any significant difference. Conclusions: 3D digital models are reliable to assess the results of upper molar distalization and can be considered a valid alternative to conventional measurement methods.

• 유통과학연구
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• 제10권12호
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• pp.5-11
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• 2012

Purpose - This paper proposes measurement models to evaluate the management performance of small and medium-sized retail businesses on the basis of a trading area analysis that compares their proposed revenue to actual revenue in the trading area. Research design, data, methodology - The study proposes measurement models consisting of five stages, namely: (1) district background survey, (2) customer survey, (3) competitor survey, (4) business district survey, and (5) business performance analysis. Results - To identify business districts easily, this study preferred a minor-adjusted method based on the Euclidean distance, as it is simple to employ for the small and medium-sized businesses. This model was applied to select coffee shops in Daejeon. Results indicated that although the targeted shop was not located in an appropriate location, actual sales were higher than expected. Conclusions - Small- or medium-sized retail businesses face difficulties regarding the economies of scale and brand recognition and must choose an appropriate location to ensure management stability. However, such businesses will find it difficult to evaluate their competitive edge accurately using a trading area analysis.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1998년도 춘계학술대회 논문집
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• pp.148-153
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• 1998

In order to control thermal deformation of machine origin of machine tools due to internal and external heat sources, the real-time compensation system has been developed. First, GMDH models were constructed to estimate thermal deformation of machine origin for a vertical machining center through the measurement of deformation data and temperature data of specific points on the machine tool. Thermocouples and gap sensors are used respectively for measurement. These models are nonlinear equations with high-order polynomials and implemented in a multilayered perceptron type network structure. Secondly, work origin shift method were developed by implementing digital I/O interface board between CNC controller and IBM-PC. The work origin shift method is to shift the work origin by the compensation amounts which is calculated by pre-established GMDH model. From the experimental result, thermal deformation of machine origin was reduced to below $\pm$5${\mu}{\textrm}{m}$.

• 한국소음진동공학회논문집
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• 제15권10호
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• pp.1169-1176
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• 2005

In this study, experimental tests for driving noise of various optical disk drives (ODD) have been performed using 1/2' microphone noise measurement system. Several new and old ODD models by different manufacturers are practically considered and compared for realistic driving conditions. Sound insulation case with absorbing material for the present experimental tests is designed and constructed using CATIA system. It is found that average data transfer rate, operating RPM, and sound noise level seem to be different for the ODD models with same denoted speed by different manufacturers. Moreover, driving sound noise level can be largely affected by both tray shape and driving speed even for the condition of the same apparent data transfer rate.