• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권12호
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• pp.6043-6062
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• 2019

Low-rank matrix decomposition has shown its capability in many applications such as image in-painting, de-noising, background reconstruction and defect detection etc. In this paper, we consider the texture background of rail track images and the sparse foreground of the defects to construct a low-rank matrix decomposition model with block sparsity for defect inspection of rail tracks, which jointly minimizes the nuclear norm and the 2-1 norm. Similar to ADM, an alternative method is proposed in this study to solve the optimization problem. After image decomposition, the defect areas in the resulting low-rank image will form dark stripes that horizontally cross the entire image, indicating the preciselocations of the defects. Finally, a two-stage defect extraction method is proposed to locate the defect areas. The experimental results of the two datasets show that our algorithm achieved better performance compared with other methods.

• 한국수소및신에너지학회논문집
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• 제27권6호
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• pp.693-701
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• 2016

Steam gasification of low rank coals is possible at relatively low temperature and low pressure, and thus shows higher efficiency compared to high rank coals. In this study, the gasification reactivity of four different Indonesian low rank coals (Samhwa, Eco, Roto, Kideco-L) was evaluated in $T=700-800^{\circ}C$. The low rank coals containing $53.8{\pm}3.4$ wt% volatile matter in proximate analysis and $71.6{\pm}1.2$ wt% carbon in ultimate analysis showed comparable gasification reactivity. In addition, $K_2CO_3$ catalyst rapidly accelerated the reaction rate at $700^{\circ}C$, and all of the coals were converted over 90% within 1 hour. The XRD analysis showed no significant difference in carbonization between the coals, and the FT-IR spectrum showed similar functional groups except for differences due to moisture and minerals. TGA results in pyrolysis ($N_2$) and $CO_2$ gasification atmosphere showed very similar behavior up to $800^{\circ}C$ regardless of the coal species, which is consistent with the steam gasification results. This confirms that the indirect evaluation of the reactivity can be made by the above instrumental analyses.

• 에너지공학
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• 제23권2호
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• pp.1-6
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• 2014

저등급석탄을 효율적으로 활용하기 위한 고품위화 기술에 대한 연구를 수행하였다. 저등급석탄을 건조시켜 고발열량 석탄으로 제조하는 과정에서 자연발화에 대한 안정화를 위해 중질유를 분무 코팅하는 방법을 적용하였다. 수분 30wt% 이상의 저등급석탄을 고품위화하여 6,000 kcal/kg 이상의 고발열량 석탄을 제조하였으며, 중질유 분무 코팅을 통해 자연발화에 대한 안정성을 확인하였다. 중질유 분무 코팅의 방법은 석탄을 건조시킨 후 분무 코팅하는 것이 가장 적절한 것으로 나타났으며, 자연발화에 대한 충분한 안정성을 갖기 위해서는 중질유를 2wt% 이상 석탄 표면에 흡착시켜야 하는 것으로 나타 났다.

• 한국식품영양학회지
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• 제27권6호
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• pp.979-989
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• 2014

The purpose of this study was to investigate the association between dietary behavior and temperament & character in preschool children, and to offer basic data that can be applied for nutrition education and counseling. A total of 211 parents of preschool children aged 3~5 years performed the Korean version of Preschool Temperament and Character Inventory (K-psTCI), a questionnaire based on Cloninger's seven-factor model of personality, along with a questionnaire about the dietary behaviors of their children. K-psTCI represented seven factors such as harm avoidance (HA), novelty seeking (NS), reward dependence (RD), persistence (P), self-directedness (SD), cooperativeness (CO), and self-transcendence (ST). The subjects were divided into either the high rank group or low rank group based on the mean score of each factor. The high rank group of HA showed significantly less physical activity and less appetite than the low rank group of HA. The children in the high rank of NS were more likely to have picky eating and a late night snack. The children in the low rank of SD or CO were more likely to have undesirable dietary behaviors, such as picky eating, too much snacking, and lower appetite than those in the high rank of SD or CO. In conclusion, individual temperament & character in preschool children may be associated with their dietary behavior, and understanding temperament & character in children may be important facts to screen and to develop an effective nutrition education program for children.

• 한국연소학회지
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• 제15권4호
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• pp.58-64
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• 2010

Spontaneous ignition tests of five different coals with non-iso-thermal and iso-thermal test method based on the standard test procedure of NF T20-036 were carried. These five coals included the 2 low rank coals and 3 bituminous coals. Test results showed that the ignition temperatures of all coals at the iso-thermal conditions were higher than that of non-isothermal condition, and those of low rank SM and BR coal in both nonisothermal and isothermal conditions were lower than bituminous AN and CN coals. The chemical species of coals such as oxygen and hematite also plays an important role in enhancing the ignition rate that the ignition temperature of SM coal was lowered. The heat accumulation tendency of five coals inside outdoor stack pile was monitored with emphasis on the change in the temperature of the coal depth in stack pile. In case of low rank BR coal, its temperature inside coal stack pile due to the rate of high heat accumulation and oxidation was $59^{\circ}C$ compared to $51^{\circ}C$ for other SW bituminous coal. And the heat accumulation rate inside coal stack piles was increased with increased the Cp value which it was defined as the specific heat of coal at constant pressure, whereas other factors such as thermal diffusivity and conductivity of coal relatively had less effect on heat accumulation.

• 청정기술
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• 제22권4호
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• pp.299-307
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• 2016

These days, coal is one of the most important energy resources used for transportation, industry, and electricity. There are two types of coal: high-rank and low-rank. Low-rank coal has a low calorific value and contains large amounts of useless moisture. The quality of low-rank coal can be increased by simple drying technology and it needs to be stabilized by hydrocarbons (e.g. palm acid oil, PAO) to prevent spontaneous combustion and moisture re-adsorption. Spontaneous combustion becomes a major problem during coal mining, storage, and transportation. It can involve the loss of life, property, and economic value; reduce the quality of the coal; and increase greenhouse gas emissions. Besides spontaneous combustion, moisture re-adsorption also leads to a decrease in quality of the coal due to its lower heating value. In this work, PAO was used for additive to stabilize the upgraded coal. The objectives of the experiments were to determine the stabilization characteristic of coal by analyzing the behavior of upgraded coal by drying and PAO addition regarding crossing-point temperature of coal, the moisture behavior of briquette coal, and thermal decomposition behavior of coal.

• 제어로봇시스템학회논문지
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• 제11권4호
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• pp.279-283
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• 2005

This paper deals with the design of a low-order H/sub ∞/ controller by using an iterative linear matrix inequality (LMI) method. The low-order H/sub ∞/ controller is represented in terms of LMIs with a rank condition. To solve the non-convex rank-constrained LMI problem, the recently developed penalty function method is applied. With an increasing sequence of the penalty parameter, the solution of the penalized optimization problem moves towards the feasible region of the original non-convex problem. Numerical experiments showed the effectiveness of the proposed algorithm.

• Current Optics and Photonics
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• 제5권4호
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• pp.431-443
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• 2021

Sparse unmixing has been proven to be an effective method for hyperspectral unmixing. Hyperspectral images contain rich spectral and spatial information. The means to make full use of spectral information, spatial information, and enhanced sparsity constraints are the main research directions to improve the accuracy of sparse unmixing. However, many algorithms only focus on one or two of these factors, because it is difficult to construct an unmixing model that considers all three factors. To address this issue, a novel algorithm called multiview-based spectral weighted and low-rank row-sparsity unmixing is proposed. A multiview data set is generated through spectral partitioning, and then spectral weighting is imposed on it to exploit the abundant spectral information. The row-sparsity approach, which controls the sparsity by the l_2,0 norm, outperforms the single-sparsity approach in many scenarios. Many algorithms use convex relaxation methods to solve the l_2,0 norm to avoid the NP-hard problem, but this will reduce sparsity and unmixing accuracy. In this paper, a row-hard-threshold function is introduced to solve the l_2,0 norm directly, which guarantees the sparsity of the results. The high spatial correlation of hyperspectral images is associated with low column rank; therefore, the low-rank constraint is adopted to utilize spatial information. Experiments with simulated and real data prove that the proposed algorithm can obtain better unmixing results.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 2015년도 추계학술대회
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• pp.108-109
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• 2015

본 논문은 low-rank 행렬의 truncated nuclear norm 최소화를 이용한 HDR (high dynamic range) 영상 합성 기법을 제안한다. 제안하는 기법에서는 기존의 LDR (low dynamic range) 영상에서 얻은 밝기의 선형 관계에 기반하여 HDR 합성을 low-rank 행렬 완성 문제로 변환한 후, ALM (augmented Lagrange multiplier) 기법을 이용하여 효율적으로 최적의 해를 구한다. 컴퓨터 모의실험을 통해 제안하는 기법이 기존 기법에 비해서 낮은 계산 복잡도를 보이면서도 더 높은 품질의 HDR 영상을 합성하는 것을 확인한다.

• ETRI Journal
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• 제36권1호
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• pp.167-170
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• 2014

In this letter, we propose an unsupervised framework for speech noise reduction based on the recent development of low-rank and sparse matrix decomposition. The proposed framework directly separates the speech signal from noisy speech by decomposing the noisy speech spectrogram into three submatrices: the noise structure matrix, the clean speech structure matrix, and the residual noise matrix. Evaluations on the Noisex-92 dataset show that the proposed method achieves a signal-to-distortion ratio approximately 2.48 dB and 3.23 dB higher than that of the robust principal component analysis method and the non-negative matrix factorization method, respectively, when the input SNR is -5 dB.