Performance Evaluations of a Novel Prototype of High Frequency Non-Contact Power Transformer

Gamage, Laknath,Ishitobi, Manabu,Nakaoka, Mutsuo The Korean Institute of Power Electronics 2004 JOURNAL OF POWER ELECTRONICS Vol.4 No.1

In this paper, a practical implementation to reduce leakage flux of a high-frequency inverter based non-contact type power transformer composed of EE-shape ferrite cores is presented for key technology of the next generation medical use X-ray CT scanner system. Design consideration for the unique structure of the non-contact power transformer with 900mm in diameter is also introduced. The complete non-contact transformer is actually arranged by several blocks of the magnetic circuit assembled by using 10 small EE shape cores with 120mm in length. It is experimentally and analytically discussed from a reduced leakage flux viewpoint related to its inductively coupling coefficient. A practical method to lower the leakage flux is described based on effective Copper-Sheet- Treatment placed on EE shape ferrite cores of magnetic circuit.

Prediction of overlapping leaf area of ice plants using digital image processing technique

( Bolappa Gamage Kaushalya Madhavi ),( Anil Bhujel ),( Jihoon Park ),( Na Eun Kim ),( Hyeon Tae Kim ) 한국농업기계학회 2021 한국농업기계학회 학술발표논문집 Vol.26 No.2

Non-destructive, fast, and accurate leaf area estimation is critical in many plant physiological and ecological experiments. In modern agriculture, ubiquitous digital cameras and scanners are primarily replaced the traditional leaf area measurements. Thus, measuring the leaflet’s dimension is integral in analysing plant photosynthesis and growth. Moreover, leaf dimension assessment with image processing is widely used for presenting. This investigation proposed a new image segmentation algorithm to classify the ice plant (Mesembryanthemum crystallinum L.) canopy image with a threshold segmentation technique by grey colour model and calculating the degree of green colour in the HSV (hue saturation value) model. Notably, the segmentation technique is used to separate suitable surfaces from a defective noisy background. Eventually, the canopy area was measured by pixel number statistics. Furthermore, this paper proposed total leaf area estimation by a computer coordinating area curvimeter and lastly evaluated the overlapping percentage using the total leaf area and canopy area measurements. To verify the effectiveness of the proposed algorithm, a segmentation experiment was performed on 24 images of ice plants. The obtained results show the algorithm’s accuracy is above 90%, which is confirmed by comparing the results of the proposed algorithm with the curvimeter leaf area method. This system gives a vital contribution to crop evolution by computational tools, making easier the monitoring work.

Empirical likelihood for change point detection in autoregressive models

Piyadi Gamage Ramadha D.,Ning Wei 한국통계학회 2021 Journal of the Korean Statistical Society Vol.50 No.1

Change point analysis has become an important research topic in many felds of applications. Several research work have been carried out to detect changes and its locations in time series data. In this paper, a nonparametric method based on the empirical likelihood is proposed to detect structural changes in the parameters of autoregressive (AR) models . Under certain conditions, the asymptotic null distribution of the empirical likelihood ratio test statistic is proved to be Gumbel type. Further, the consistency of the test statistic is verifed. Simulations are carried out to show that the power of the proposed test statistic is signifcant. The proposed method is applied to monthly average soybean sales data to further illustrate the testing procedure.

STRAWBERRY LEAF COLOR ESTIMATION USING MACHINE LEARNING APPROACHES BASED ON SOIL PHYSICOCHEMICAL PARAMETERS

( Bolappa Gamage Kaushalya Madhavi ),( Gun Ho Lee ),( Hyeon Tae Kim ) 한국농업기계학회 2022 한국농업기계학회 학술발표논문집 Vol.27 No.2

Soil physicochemical parameters are crucial for strawberry growth and optimal production under greenhouse cultivation. The Strawberry leaf is a typical vegetative organ for determining the plant's growth status. Moreover, strawberry leaf colour analyses are the best approach to assess soil status and protect against over-fertilization. This study investigated to development of machine learning models such as multiple linear regression (MLR) and gradient boost regression (GBR), using RGB (red, green, and blue) mean values for simulating strawberry leaf colour variations based on soil physicochemical parameters and plant age. Simultaneously, the soil physicochemical parameters of different coloured strawberry leaves were precisely measured by a multifunctional soil sensor. Synchronously, 400 strawberry leaflets were detached in each vegetative and reproductive stage, and individual leaves were captured using a digital imaging system. The RGB mean values of coloured images were extracted using the image segmentation algorithms. Subsequently, MLR and GBR models were developed to predict the leaf RGB mean values related to soil physicochemical measurement and plant age. The GBR model vigorously fitted with RGB mean values throughout the growth stage, with R2 and RMSE values of (R = 0.77, 7.16, G = 0.72, 7.37, and B = 0.70, 5.68), respectively. Furthermore, the MLR model performed moderately with R2 and RMSE values of (R = 0.67, 8.59, G = 0.57, 9.12, and B = 0.56, 6.81) when consecutively predicting RGB mean values in strawberry leaves. Eventually, the GBR model performed more effectively than the MLR model with high-evaluation metrics. Additionally, the leaf colour model accurately predicts dynamic changes in strawberry leaf colour and uses visualization technology to track growth progress.

Performance Evaluations of a novel Prototype of high Frequency Non-Contact Power Transformer

Laknath Gamage,Manabu Ishitobi,Mutsuo Nakaoka 전력전자학회 2004 JOURNAL OF POWER ELECTRONICS Vol.4 No.1

In this paper, a practical implementation to reduce leakage flux of a high-frequency inverter based non-contact type power transformer composed of EE-shape ferrite cores is presented for key technology of the next generation medical use X-ray CT scanner system Design consideration for the unique structure of the non-contact power transformer with 900mm in diameter is also introduced The complete non-contact transformer is actually arranged by several blocks of the magnetic circuit assembled by using 10 small EE shape cores with 120mm in length It is experimentally and analytically discussed from a reduced leakage flux viewpoint related to its inductively coupling coefficient A practical method to lower the leakage flux is described based on effective Copper-Sheet-Treatment placed on EE shape ferrite cores of magnetic Circuit.

Intelligent optimization of axial-flow pump using physics-considering machine learning

KANKANAM GAMAGE PIYUMIKA MADUSHANI,Zhou Jie,Feng Jiangang,XUHUI ZHOU,Yuan Zheng,Chen Huixiang,Chen Jinbo 한국CDE학회 2024 Journal of computational design and engineering Vol.11 No.1

To address the significant energy waste generated by axial flow pumps, this paper proposes an intelligent optimization method based on physics-considering machine learning. First, a highly parameterized geometric design theory is constructed using six featured variables to achieve a complete three-dimensional modeling of the blade geometry. Four hundred preliminary cases are studied using the computational fluid dynamics method with various combinations of these featured variables to obtain a preliminary solution. The best preliminary design has an efficiency of 83.33%, and a head of 5.495 m. To further improve this performance, this paper also presents a high-precision prediction model for the energy performance of axial flow pump based on back-propagation neural network and the encoding layers of random sampling and local feature aggregator network created. Afterwards, a multi-population genetic algorithm is used to quickly find the optimal solution within the prediction mode range. The algorithm achieved a highest efficiency of 86.373% and was validated by numerical simulation with a value of 86.057% and a prediction error of 0.316%. Compared with the preliminary solution, the efficiency of the optimized axial flow pump is increased by 1.615%, with a wider high-efficiency range and an optimal operating point closer to the design conditions. Overall, this intelligent optimization method has the potential to significantly reduce the design time of axial pumps and increase their performance.

Why Chinese travelers use WeChat to make hotel choice decisions: A uses and gratifications theory perspective

Thilini Chathurika Gamage,Kayhan Tajeddini,Omid Tajeddini 한국마케팅과학회 2022 마케팅과학연구 Vol.32 No.2

WeChat, a Chinese multi-purpose messaging, social media, and mobile payment app, is an emerging social media platform that has been integrated into the daily lives of Chinese people, including travel. However, despite the growing proliferation of WeChat, sur- prisingly, little attention has been paid to the gratifications obtained by Chinese travelers when using WeChat in travel- related decision-making. Adopting the well-grounded Uses and Gratifications Theory (UGT), this exploratory research paper aims to address this void in prior literature and identify why and how Chinese millennial travelers use WeChat to make hotel choice decisions. Findings stemmed from the semi-structured interviews using a combination of purposive and snowball sampling approaches with eighteen WeChat users reveals that hotel choice decisions through WeChat are influenced by various social, process, and content gratifications. As indicated in our findings, hotels in China should be aware of gratifications obtained by travelers in stimulating them to utilize WeChat in the hotel selection process. Further, our study contributes to extant UGT literature by empha- sizing that it has specific relevance and should be given more prominence within tourism, hospitality, and social media literature.

Probiotic Properties of Lactobacillus brevis KU200019 and Synergistic Activity with Fructooligosaccharides in Antagonistic Activity against Foodborne Pathogens

Kariyawasam Majuwana Gamage Menaka Menike Kariyawasam,Seo Jin Yang,Na-Kyoung Lee,Hyun-Dong Paik 한국축산식품학회 2020 한국축산식품학회지 Vol.40 No.2

This study aims to evaluate the probiotic properties of Lactobacillus brevis (L. brevis) KU200019 and the synergistic activity with prebiotics on antimicrobial activity, and the potential application as an adjunct culture in fermented dairy products. The commercial strain, L. brevis ATCC 14869 was used as reference strain. L. brevis KU200019 was showed higher viability in simulated gastric (99.38±0.21%) and bile (115.10±0.13%) conditions compared to reference strain. L. brevis KU200019 exhibited antimicrobial activity against various foodborne pathogens. The supplementation of fructooligosaccharides (FOS) enhanced viability of lactic acid bacteria (>8 Log CFU/mL) and antioxidant activity [2,2- diphenyl-2-picrylhydrazyl radical assay (DPPH) assay, 31.23±1.14%; 2,2-azinobis (3- ethylbenzothiazoline-6-sulfonic acid (ABTS) assay, 38.82±1.46%] in fermented skim milk during refrigerated storage. L. brevis KU200019 was distinguished from the reference strain by its higher probiotic potential, antimicrobial activity, and higher antioxidant activity in fermented milk. Therefore, L. brevis KU200019 with FOS was demonstrated promising properties for further application in fermented dairy products with enhanced safety and quality.

The Locative of Cause Discounted: A Study of the Grammatical Exegeses in the Mahāvihāra Buddhist School

Aruna-Keerthi GAMAGE 동국대학교 불교학술원 2023 International Journal of Buddhist Thought & Cultur Vol.33 No.2

By analysing the glosses on the locative of cause (nimittasattamī or hetu) that appear in the exegetical works of the Mahāvihāra school, a branch of Theravāda Buddhism, this article proposes alternative renderings to existing English translations of some words in the received Theravāda canon (‘Tipiṭaka or Triple basket’). This study focuses primarily on the exegetical works of the Mahāvihāra school—Aṭṭhakathās or commentaries and Ṭīkās or subcommentaries—written in Sri Lanka in the first to early second millennium, in tandem with the relevant texts in the canon and their corresponding English translations. The grammatical analysis of the words and phrases of the canon is one of the hermeneutical strategies of the exegetical works of the Mahāvihāra school. Needless to say, these analyses are crucial to determining more appropriate interpretations of the canon. Among these grammatical analyses, the glosses on the locative of cause play a vital role. The Mahāvihāra exegetes offer a wealth of analysis on the locative of cause. While the commentaries recognize some cause-locatives in the canon, the subcommentaries also identify some of those not identified in the commentaries. Although the majority of scholars who translated the texts of the canon into English consulted the commentaries, only a handful consulted the subcommentaries. This is apparently one of the reasons why some important explanations about causal locatives in the canon are not taken into account. Although some of the leading scholars saw such analyses in these exegetical works, they did not consider adapting their translations in light of the analyses of cause-locatives. They often translated cause-locatives as simple locatives. This article highlights the importance of translating cause-locatives in the canon as cause-locatives and how these analyses are helpful for the reader to reach a much deeper level of understanding of the teachings in the canon.

Effect of set-type yoghurt supplemented with the novel probiotic Lantiplantibacillus plantarum 200655 on physicochemical properties and the modulation of oxidative stress-induced damage

Kariyawasam Majuwana Gamage Menaka Menike Kariyawasam,이나경,백현동 한국식품과학회 2023 Food Science and Biotechnology Vol.32 No.3

The present study developed a functional yoghurt supplemented with Lantiplantibacillus plantarum 200655 and evaluated its physicochemical properties and antioxidant activities. Yoghurt samples were prepared using commercial starter cultures and probiotics and grouped as follows: control sample without probiotics (C), GG (supplemented with Lacticaseibacillus rhamnosus GG), R (supplemented with L. plantarum KCTC 3108), and S (supplemented with L. plantarum 200655). The GG, R, and S samples had shorter fermentation time compared with the C sample. Lactic acid bacteria count, pH, and titratable acidity were similar in all samples during refrigerated storage. However, the GG, R, and S samples showed increased viscosity and water holding capacity (WHC), and decreased syneresis. The S sample had no adverse effect on organoleptic properties. Furthermore, the S sample had the highest antioxidant activity and significantly inhibited LPS-induced oxidative stress in intestinal cells. These findings suggest the potential use of L. plantarum 200655 in dairy products with therapeutic benefits.