• Environmental Engineering Research
• /
• 제10권3호
• /
• pp.105-111
• /
• 2005

The applicability of the USEPA's (United States Environmental Protection Agency) three criteria of enhanced coagulation (criterion 1-TOC level less than 2 mg/l. before chlorination; criterion II-% requirement of TOC removal; criterion III-point of diminishing return) for Korean waters was evaluated in this study. This study also investigated an effect of enhanced coagulation on turbidity removal, and attempted to identify the best coagulant for enhanced coagulation. Three different waters were used in this study: one river water and two lake waters. five different coagulants were used: alum, liquid alum, PACl, ferric chloride with and without water. Results of this study showed that all three criteria were achievable for the tested waters. For these waters, controlling criterion was found to be different depending upon raw water characteristics. When initial Toe level was low(< 4 mg/L), criterion I (< 2 mg/L) could be the controlling criterion. As TOC level increased, criterion II (% TOC removal) became the controlling criteria. It was possible to achieve different goals of turbidity and TOC removals. Although the optimum region of TOC removal was more acidic than that of turbidity removal, there was no conflict between these two removals. The best coagulant was found to be different depending upon the evaluation tool: maximum and optimum removal. ferric chloride was more effective than alum in terms of the maximum TOC removal, while Al-based coagulant such as alum or PACl was the best coagulant in terms of the optimum TOC removal.

• Journal of Power Electronics
• /
• 제18권6호
• /
• pp.1683-1696
• /
• 2018

Under the conventional control strategy, the asymmetry of arm impedances may result in the poor operating performance of modular multilevel converters (MMCs). For example, fundamental frequency oscillation and double frequency components may occur in the dc and ac sides, respectively; and submodule (SM) capacitor voltages among the arms may not be balanced. This study presents an enhanced control strategy to deal with these problems. A mathematical model of an MMC with asymmetric arm impedance is first established. The causes for the above phenomena are analyzed on the basis of the model. Subsequently, an enhanced current control with five integrated proportional integral resonant regulators is designed to protect the ac and dc terminal behavior of converters from asymmetric arm impedances. Furthermore, an enhanced capacitor voltage control is designed to balance the capacitor voltage among the arms with high efficiency and to decouple the ac side control, dc side control, and capacitor voltage balance control among the arms. The accuracy of the theoretical analysis and the effectiveness of the proposed enhanced control strategy are verified through simulation and experimental results.

• International Journal of Computer Science & Network Security
• /
• 제22권5호
• /
• pp.143-148
• /
• 2022

Brain tumor classification is an important process that allows doctors to plan treatment for patients based on the stages of the tumor. To improve classification performance, various CNN-based architectures are used for brain tumor classification. Existing methods for brain tumor segmentation suffer from overfitting and poor efficiency when dealing with large datasets. The enhanced CNN architecture proposed in this study is based on U-Net for brain tumor segmentation, RefineNet for pattern analysis, and SegNet architecture for brain tumor classification. The brain tumor benchmark dataset was used to evaluate the enhanced CNN model's efficiency. Based on the local and context information of the MRI image, the U-Net provides good segmentation. SegNet selects the most important features for classification while also reducing the trainable parameters. In the classification of brain tumors, the enhanced CNN method outperforms the existing methods. The enhanced CNN model has an accuracy of 96.85 percent, while the existing CNN with transfer learning has an accuracy of 94.82 percent.

• Investigative Magnetic Resonance Imaging
• /
• 제26권1호
• /
• pp.60-65
• /
• 2022

Gadoxetic acid-enhanced magnetic resonance imaging (MRI) has been widely used to detect and characterize focal hepatic lesions. Because gadoxetic acid is a hepatocyte-specific contrast agent, its patterns during hepatobiliary phase enhancement provide useful information for differential diagnoses of focal hepatic lesions. Hepatic angiomyolipoma (AML) is a rare mesenchymal hepatic neoplasm composed of blood vessels, epithelioid cells, and varying amounts of adipose tissue components. Hepatic AMLs usually show marked hypointensity during the hepatobiliary phase of gadoxetic acid-enhanced MRI as hepatic AMLs are devoid of hepatocytes and fibrotic components. The present study describes a patient with hepatic AML and an atypical imaging feature. This tumor showed hyperintensity during the hepatobiliary phase of gadoxetic acid-enhanced MRI, mimicking hepatocellular tumors such as hepatocellular adenoma. The hepatobiliary hyperintensity of this lesion was likely due to multifocal entrapped hepatocytes resulting from an intrasinusoidal growth pattern of tumor cells and insufficient hepatic parenchymal enhancement during the hepatobiliary phase of gadoxetic acid-enhanced MRI.

• ETRI Journal
• /
• 제31권5호
• /
• pp.613-615
• /
• 2009

We propose a pilot-based coding (PBC) scheme for lossless bit rate reduction of parametric stereo (PS) in enhanced aacPlus. It uses PBC in addition to the existing frequency and time differential coding to encode and decode PS parameter indexes. We also design optimal Huffman codebooks (HCBs) for PBC in the proposed scheme. Experiments show that the proposed scheme is superior to the original coding scheme, where both the new coding structure and the optimal HCBs contribute to the bit rate reduction.

• 한국정보과학회:학술대회논문집
• /
• 한국정보과학회 2004년도 봄 학술발표논문집 Vol.31 No.1 (A)
• /
• pp.721-723
• /
• 2004

오늘날의 인터넷은 QoS를 보장하기 위해 다양한 방법을 사용하고 있는데, 본 논문에서는 Integrated-QoS 개념을 제안하고 이를 기반으로 Admission Control을 실행하는 Enhanced Differentiated Service(DiffServ)를 설계하였다. 본 논문은 IntServ(Integrated Service)와 DiffServ(Differentiated Service)의 장점을 결합하여, EF 클래스에 속하는 다수의 흐름들(flows)에 기존보다 QoS가 더욱 보장된 서비스를 제공할 수 있는 방안을 제시한다.

• 천문학회보
• /
• 제42권2호
• /
• pp.43.2-43.2
• /
• 2017

We report our discovery of a significant population of CN-enhanced red clump stars in the classical bulge component of the Milky Way. Since CN-rich stars trace a population with enhanced Helium, Nitrogen, and Sodium originated in globular clusters (GCs), this is a direct evidence that proto-GCs were the major building blocks in the formation of the classical bulges and early-type galaxies in the hierarchical merging paradigm.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 1999년도 하계종합학술대회 논문집
• /
• pp.922-925
• /
• 1999

The Silylation photo-resist etch process was tested by Enhanced-ICP dry etcher. The comparison of the two process results of micro pattern etching with 0.25${\mu}{\textrm}{m}$ CD by E-ICP and ICP reveals that E-ICP has better quality than ICP The etch rate and the microloading effect was improved in E-ICP Especially, the problem of the lateral etch was improved in E-ICP.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2004년도 춘계학술대회논문집
• /
• pp.400-403
• /
• 2004

This paper presents an optimum design of journal bearings using a hybrid method to find the solutions of optimization problem. The present hybrid algorithm, namely Enhanced Artificial Life Algorithm(EALA), is a synthesis of an artificial life algorithm(ALA) and the random tabu search(R-tabu) method. EALA is applied to the optimum design of journal bearings supporting simple rotor. The applicability of EALA to optimum design of rotor-bearing system is exemplified through this study.

• 한국지하수토양환경학회:학술대회논문집
• /
• 한국지하수토양환경학회 2003년도 추계학술발표회
• /
• pp.413-416
• /
• 2003

Micellar enhanced ultrafiltration(MEUF) is a surfactant-based separtaion technique which can remove dissolved organics or multivalent ions from water. In this study, trichloroethylene(TCE) and chromate were simultaneouly removed using MEUF and cetyltrimethylammoniun chloride (CPC) was used as a surfactant. The removal efficiency of chromate was 99% and that of TCE was more than 80%. The presence of TCE or chromate did not affect removal efficiency of each pollutants because the predominat mechanism of TCE and chromate are different.