• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2015년도 학술발표회
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• pp.537-537
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• 2015

In recent decades, the independence and identical distribution (iid) assumption for extreme events has been shown to be invalid in many cases because long-term climate variability resulting from phenomena such as the Pacific decadal variability and El Nino-Southern Oscillation may induce varying meteorological systems such as persistent wet years and dry years. Therefore, in the current study we propose a new parameter estimation method for probability distribution models to more accurately predict the magnitude of future extreme events when the iid assumption of probability distributions for large-scale climate variability is not adequate. The proposed parameter estimation is based on a metaheuristic approach and is derived from the objective function of the rth power probability-weighted sum of observations in increasing order. The combination of two distributions, gamma and generalized extreme value (GEV), was fitted to the GEV distribution in a simulation study. In addition, a case study examining the annual hourly maximum precipitation of all stations in South Korea was performed to evaluate the performance of the proposed approach. The results of the simulation study and case study indicate that the proposed metaheuristic parameter estimation method is an effective alternative for accurately selecting the rth power when the iid assumption of extreme hydrometeorological events is not valid for large-scale climate variability. The maximum likelihood estimate is more accurate with a low mixing probability, and the probability-weighted moment method is a moderately effective option.

• Wind and Structures
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• 제11권1호
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• pp.19-33
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• 2008

This research investigates the adaptive input estimation method applied to the multilayer shearing stress structure. This method is to estimate the values of wind load inputs by analyzing the active reaction of the system. The Kalman filter without the input term and the adaptive weighted recursive least square estimator are two main portions of this method. The innovation vector can be produced by the Kalman filter, and be applied to the adaptive weighted recursive least square estimator to estimate the wind load input over time. This combined method can effectively estimate the wind loads to the structure system to enhance the reliability of the system active performance analysis. The forms of the simulated inputs (loads) in this paper include the periodic sinusoidal wave, the decaying exponent, the random combination of the sinusoidal wave and the decaying exponent, etc. The active reaction computed plus the simulation error is regard as the simulated measurement and is applied to the input estimation algorithm to implement the numerical simulation of the inverse input estimation process. The availability and the precision of the input estimation method proposed in this research can be verified by comparing the actual value and the one obtained by numerical simulation.

• Journal of Positioning, Navigation, and Timing
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• 제7권4호
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• pp.245-253
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• 2018

The current SBAS service does not provide a method to integrate multiple SBAS corrections. This paper proposes a positioning method to effectively integrate multiple SBAS and multiple GNSS. In the method, the final position is obtained by the weighted sum of the positions obtained from the combination of GNSS and SBAS. Since each position is independently computed and combined using flexible weights, it has a simple structure that can easily cope with various environments. In order to verify the operation and performance of the proposed method, raw measurements of GNSS and SBAS were collected using commercial receivers. The experiments using real signals show that the combined use of two SBAS corrections was more accurate by 0.05~0.4m(2dRMS) than using only one SBAS correction. To improve the position accuracy, this paper considered the integration of multi-GNSS and multi-SBAS, which was not found in other existing studies. The proposed method is expected to be a core technology for designing multi-GNSS navigation receivers considering multi-SBAS corrections. The importance of the method will be increased as KPS and KASS also available in near future.

• International Journal of Naval Architecture and Ocean Engineering
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• 제12권1호
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• pp.617-635
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• 2020

The purpose of this study is to discuss how to improve the maneuverability of lifting and diving for underwater vehicle's vertical motion. Therefore, to solve these problems, applied the 3-D numerical simulation, Taguchi's Design of Experiment (DOE), and intelligent parameter design methods, etc. We planned four steps as follows: firstly, we applied the 2-D flow simulation with NACA series, and then through the Taguchi's dynamic method to analyze the sensitivity (β). Secondly, take the data of pitching torque and total resistance from the Taguchi orthogonal array (L9), the ignal-to-noise ratio (SNR), and analysis each factorial contribution by ANOVA. Thirdly, used Radial Basis Function Network (RBFN) method to train the non-linear meta-modeling and found out the best factorial combination by Particle Swarm Optimization (PSO) and Weighted Percentage Reduction of Quality Loss (WPRQL). Finally, the application of the above methods gives the global optimum for multi-quality characteristics and the robust design configuration, including L/D is 9.4:1, the foreplane on the hull (Bow-2), and position of the sail is 0.25 Ls from the bow. The result shows that the total quality is improved by 86.03% in comparison with the original design.

• 한국멀티미디어학회논문지
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• 제25권8호
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• pp.1059-1068
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• 2022

Recently, research using image-based deep learning is being conducted to determine similar fonts or recommend fonts. In order to increase the accuracy in judging the similarity of Hangul fonts, a previous study was conducted to calculate the similarity according to the combination of stroke elements. In this study, we tried to solve this problem by designing an integrated model that reflects the weights for each stroke element. By comparing the results of the user's font similarity calculation conducted in the previous study and the weighted model, it was confirmed that there was no difference in the ranking of the influence of the stroke elements. However, as a result of comparison by letter sizes, it was confirmed that there was a difference in the ranking of the influence of stroke elements. Accordingly, we proposed a weighted model set separately for each font size.

• 한국수자원학회논문집
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• 제42권4호
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• pp.297-307
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• 2009

신뢰도 높은 수질 모의를 위해서는 유역 내 정확한 유출 모의가 반드시 선행되어야 한다. 본 연구에서는 연속방정식과 운동파 근사에 의한 Manning의 식이 결합된 비선형 저류방정식에 근거한 하도추적법과 금일 강수량을 고려하여 시간적으로 가중 평균된 유출곡선지수를 산정하도록 개선된 지표유출계산 모듈이 수질 모의에 미치는 영향을 분석하였다. 이를 대표적 준분포형 모형인 SWAT에 탑재하여 충주댐 유역에 적용하여 각 개선모듈별 독립적인 분석과 전체 개선의 효과를 개선 전 후로 분석하였다. 각 개선 모듈별 수질 모의의 기여도를 분석한 결과 지표유출계산 모듈의 개선보다는 하도추적의 개선이 더 많은 영향을 미치는 것으로 분석되었다. 이는 비점오염원의 특성 상 하도추적의 개선으로 인한 유출 지체 현상의 개선이 부하량의 배출에 가장 큰 요인으로 작용하였기 때문이라고 판단된다.

• 한국멀티미디어학회논문지
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• 제11권11호
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• pp.1615-1623
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• 2008

이 논문에서는 곤충 발자국의 패턴을 찾아 개체를 인식하기 위해서, 개선된 SOM 알고리즘과 ART2 알고리즘을 사용하여 인식의 기본 영역을 추출한다. 또한 Trace 변환을 이용하여 발자국의 인식에 필요한 특징을 추출하고 개체를 판단하는 기법을 제안한다. 제안한 기법에서는 모폴로지 기법을 이용하여 region을 먼저 찾고, 개선된 SOM과 ART2 알고리즘을 이용하여 곤충의 크기와 종류에 관계없이 세그먼트를 추출한다. 그리고 곤충 발자국과 같이 다양한 변형이 존재하는 패턴에 적합한 특징값을 찾기 위해서 Trace 변환을 이용하고, 함수의 조합으로 재구성된 Triple 특징값을 이용하여 곤충별로 고유한 패턴을 찾아 인식 실험을 수행한다. 곤충 발자국에서 명확한 발자국과 그렇지 못한 발자국을 자동으로 결정하는 것이 매우 어렵다. 따라서 이와 같이 불확실한 대상을 제외시키지 않고 가능성의 대상으로 판단하고 분류하기 위해서 퍼지 가중치 평균을 이용하여 인식을 수행한다. 제안한 방법에 의한 곤충 발자국의 영역 추출과 인식 실험을 실시하고 그 결과를 제시하였다.

• 한국정보통신학회논문지
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• 제17권6호
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• pp.1399-1408
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• 2013

본 논문은 유도전동기의 제어에 있어서 성능향상을 위하여 가중치를 도입한 새로운 적분제어기법을 제안하여 $H_{\infty}$ T-S 퍼지제어기와 함께 사용하였다. $H_{\infty}$ T-S퍼지제어기는 유도전동기의 비선형성과 강인성을 위하여 사용되었고 가중치를 도입한 적분제어기는 추적문제를 조정기문제로 바꾸어 줌과 동시에 제어성능을 향상시키기 위해서 사용되었다. $H_{\infty}$ T-S퍼지제어기는 국부선형모델을 기반으로 구해지는 국부선형제어기 들의 선형결합으로 구성되며 각각의 국부 선형제어이득들은 LMI(Linear Matrix Inequlity)를 이용하여 계산된다. 본 논문에서는 가중치에 따라 결정되는 다양한 LMI해의 선택을 가능하게 함으로써 제어성능을 향상시켰다.

• Journal of Digestive Cancer Research
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• 제1권2호
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• pp.108-110
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• 2013

전체 정맥혈색전증 환자의 20% 이상이 암과 관련이 있고, 암 환자에 있어 혈색전증은 두 번째 사망 원인으로 작용하고 있어 이에 대한 효과적인 예방과 치료가 사망률을 감소시킬 수 있는 것으로 알려져 있다. 혈색전증 진단에 있어 혈액검사로 D-dimer 측정 및 영상검사로 도플러 초음파, 전산화단층혈관 촬영술을 사용한다. 치료 약제로 경구 비타민 K 길항제가 사용되었으나, 최근에는 정기적인 모니터링이 필요하지 않은 약제들이 새롭게 사용되고 있다. 저자들은 진행성 위암환자에서 발생한 하지 심부정맥 혈전증 및 폐동맥 혈색전증에 있어 저분자량 헤파린을 투여하며, 호전된 사례를 문헌고찰과 함께 보고하는 바이다.

• Imaging Science in Dentistry
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• 제54권3호
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• pp.289-295
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• 2024

Purpose: This study examined the influence of metal artifact reduction (MAR), the application of sharpening filters, and their combination on the diagnosis of horizontal root fracture (HRF) in teeth adjacent to a zirconia implant on cone-beam computed tomography (CBCT) examinations. Materials and Methods: Nineteen single-rooted teeth (9 with HRF and 10 without) were individually positioned in the right central incisor socket of a dry human maxilla. A zirconia implant was placed adjacent to each tooth. Imaging was performed using an OP300 Maxio CBCT (Instrumentarium, Tuusula, Finland) unit with the following settings: a current of 8 mA, both MAR modes(enabled and disabled), a 5×5 cm field of view, a voxel size of 0.085 mm, and a peak kilovoltage of 90 kVp. Four oral and maxillofacial radiologists independently evaluated the CBCT scans under both MAR conditions and across 3 levels of sharpening filter application (none, Sharpen 1×, and Sharpen 2×). Diagnostic metrics were calculated and compared using 2-way analysis of variance (α=5%). The weighted kappa test was used to assess intra- and inter-examiner reliability in the diagnosis of HRF. Results: MAR tool activation, sharpening filter use, and their combination did not significantly impact the area under the receiver operating characteristic curve, sensitivity, or specificity of HRF diagnosis (P>0.05). Intra- and inter-examiner agreement ranged from fair to substantial. Conclusion: The diagnosis of HRF in a tooth adjacent to a zirconia implant is not affected by the activation of MAR, the application of a sharpening filter, or the combination of these tools.