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      • KCI등재후보

        Classification of strawberry ripeness stages using machine learning algorithms and colour spaces

        Karki Sijan,Basak Jayanta Kumar,Paudel Bhola,Deb Nibas Chandra,김나은,국정후,강명용,김현태 한국원예학회 2024 Horticulture, Environment, and Biotechnology Vol.65 No.2

        Accurate classifi cation of strawberry ripeness is a crucial aspect of ensuring high-quality food products, optimizing harvest ing and storage processes, and promoting consumer health. Although several non-destructive computer vision-based systems have been developed for this purpose, the infl uence of diff erent colour spaces on machine-learning model performance dur ing the ripeness stage classifi cation of strawberries remains underexplored. In this context, three machine-learning models, namely Gaussian Naïve Bayes (GNB), support vector machine (SVM) and feed-forward artifi cial neural networks (FANN), were combined with four colour spaces (RGB, HLS, CIELab and YCbCr) and biometrical characteristics to evaluate the eff ectiveness of colour spaces on the performance of machine-learning models for classifying strawberry ripeness. For this purpose, 1210 samples were collected and manually classifi ed into four ripeness stages. A dataset was created by combining each colour space value, biometrical properties, and corresponding ripeness stage, which was used as inputs to the models. The results indicated that FANN with CIELab colour space achieved the highest accuracy of 96.7%, followed by GNB and SVM, both having equal accuracy of 95.46% in CIELab colour space. The least accuracy of 92.15% was observed in RGB colour space with the GNB classifi er. In this study, the unripe and over-ripe stages were more accurately classifi ed, while intermediate ripening stages proved to be more challenging for the models. Furthermore, the accuracy of models was observed to be infl uenced by both the colour space and classifi cation model selected. Additionally, further research is needed to investigate other features that could improve the performance of models for strawberry ripeness classifi cation.

      • Performance Analysis of Fluidized Bed and Downdraft Fixed Bed Reactors in Torrefaction using Sewage Sludge

        ( Karki Sujeeta ),( Ja Hyung Choi ),( Jeeban Poudel ),( Sea Cheon Oh ) 한국폐기물자원순환학회(구 한국폐기물학회) 2018 한국폐기물자원순환학회 심포지움 Vol.2018 No.1

        Comparative analysis of the performance of fluidized bed and downdraft fixed bed reactor in torrefaction is the primary objective of the research. Many researches have focused on the performance of fixed bed reactors with a few published works in fluidized bed. However, no research has focused on the comparison of fluidized bed and downdraft fixed bed reactors in spite of their immense potential as torrefaction reactors. Sewage sludge was taken as the raw material to study the torrefaction characteristics. The effects of the main torrefaction variables, temperature and residence time, on the performance parameters such as fixed carbon, calorific value; molar ratios, ultimate and proximate analysis, chemical exergy etc. were investigated for torrefied sewage sludge. Although continuous research with multiple replicated data is required before developing a concrete conclusion, the study showed that the fixed bed reactor is more favorable compared to fluidized bed despite the leverage that fluidized bed offers.

      • Comparative Analysis of Torrefaction Characteristics of Sewage Sludge using Fluidized and Downdraft Fixed Bed Reactors

        Karki Sujeeta,Ja hyung Choi,Jeeban Poudel,Sea Cheon Oh 한국폐기물자원순환학회 2018 한국폐기물자원순환학회 학술대회 Vol.2018 No.05

        The aim of this project was to explore the potential of the torrefaction treatment for upgrading sewage sludge into valuable product. An ancillary investigation on the cold fluidization and the behavior of sewage sludge was analyzed. The effects of the main torrefaction variables, temperature and residence time, on the performance parameters such as fixed carbon, calorific value; molar ratios, ultimate and proximate analysis, chemical exergy etc. were investigated for torrefied sewage sludge. Results for both the reactors showed that the thermochemical transformations that sewage sludge underwent, as a results of the release of volatile matter due to thermal decomposition of its organic constituents, resulted in significant improvement of their chemical and physical properties. Results obtained from this study showed that despite the leverage that fluidized bed offers (heat and mass transfer) fixed bed configuration was more pronounced for torrefaction of sewage sludge. However, a decisive conclusion cannot be made at this stage as more detail study would be required to draw a definitive conclusion over the preference of reactor for torrefaction.

      • KCI등재

        Effect of Sowing Time on Germination and Early Seedling Growth of Quercus floribunda Lindl.

        Karki, Himani,Bargali, Kiran,Bargali, SS Institute of Forest Science 2018 Journal of Forest Science Vol.34 No.3

        Quercus floribunda (Tilonj oak) is among the five species of Quercus and an evergreen tree found in Kumaun Himalayan region. Timing of germination is a crucial event determining the success of seedling establishment and survival. The aims of the study were to investigate the effect of sowing date on the germination and morphological responses of Tilonj oak (Quercus floribunda), cultivated during the month of August-September, with supplementary irrigation. The experiment was conducted by sowing seeds at two dates with one month interval in glass house conditions at DSB Campus, Nainital, Uttarakhand, India. Present study revealed that higher germination percentage (46.67 %) was recorded at sowing time $S_2$ as compared to the sowing time $S_1$ (32.86 %). Germination percentage as well as seedling growth were affected by sowing date though the differences were insignificant. At both the sowing dates, highest germination percentage was recorded for large seeds (32.86-46.67 %) followed by medium (31.43-33.33 %) and lowest germination (6.67-7.14 %) was recorded for small size seeds. In all parameters assessed, sowing time $S_2$ had the best performance in combination with large seed size. Thus, September is suitable month for best germination, growth and seedling vigour and large seed size is recommended to silviculturists and tree planters. The information on seed germination and seedling growth is vital both for conservation and rehabilitation of degraded lands.

      • 1P-628 Thermal Pre-treatment of Sewage Sludge in Fluidized Bed for Enhancing its Solid Fuel Properties

        ( Karki Sujeeta ),( Poudel Jeeban ),오세천 한국공업화학회 2017 한국공업화학회 연구논문 초록집 Vol.2017 No.1

        In the present work, fluidization of sewage sludge, a non-lignocellulosic biomass, was studied using a bench scale fluidized bed. The influence of torrefaction temperature ranging from 200 - 350°C and residence time of 0 - 50 minutes on the physical and chemical properties of sewage sludge was investigated. The properties of torrefied product were analyzed on the basis of degree of torrefaction, ultimate and proximate analysis, gas analysis and chemical exergy. The degree of torrefaction and chemical exergy showed positive influence on increasing the torrefaction temperature. The effect of torrefaction temperature and residence time was studied on elemental variation of sewage sludge which exhibited a decrease of H/C and O/C ratios. The product gas emitted during torrefaction was analyzed to study the pathway of hydrocarbons and oxygen containing compounds. Torrefaction using fluidized bed improved the overall physiochemical properties of sewage sludge.

      • SCISCIESCOPUS

        Physical, optical and luminescence properties of B<sub>2</sub>O<sub>3</sub>-SiO<sub>2</sub>-Y<sub>2</sub>O<sub>3</sub>-CaO glasses with Sm<sup>3+</sup>ions for visible laser applications

        Karki, Sujita,Kesavulu, C.R.,Kim, H.J.,Kaewkhao, J.,Chanthima, N.,Ruangtaweep, Y. Elsevier 2018 Journal of luminescence Vol.197 No.-

        <P><B>Abstract</B></P> <P>Silicoborate glasses with composition of (BSYCaSm:(55-x)B<SUB>2</SUB>O<SUB>3</SUB>+ 10SiO<SUB>2</SUB> +25Y<SUB>2</SUB>O<SUB>3</SUB> +10CaO + xSm<SUB>2</SUB>O<SUB>3</SUB>), (where, x= 0.05, 0.10, 0.20, 0.25, 0.30, 0.40, 0.50, mol%) have been synthesized by using the well-known melt quenching technique. The present work deals with physical, optical, photoluminescence, X-ray luminescence and decay time studies of silicoborate glasses. Judd-Ofelt (JO) intensity parameters (Ω<SUB>2,</SUB> Ω<SUB>4</SUB> and Ω<SUB>6</SUB>) and radiative properties for the important luminescent level of Sm<SUP>3+</SUP> ions were derived by using the absorption spectrum of 0.3mol% Sm<SUB>2</SUB>O<SUB>3</SUB> doped glass. The luminescence spectra in the visible region was obtained due to <SUP>4</SUP>G<SUB>5/2</SUB> → <SUP>6</SUP>H<SUB>J</SUB> (5/2, 7/2, 9/2 and 11/2) transition of Sm<SUP>3+</SUP> ion under 401nm excitation. The decay profile for the <SUP>4</SUP>G<SUB>5/2</SUB> level of Sm<SUP>3+</SUP> ions was analyzed and found that for lower concentration (≤ 0.20mol%) it is single exponential in nature whereas for higher concentration (≥ 0.25mol%), it turns in to non-exponential due to the transfer of energy between donor (excited state Sm<SUP>3+</SUP>ion) and acceptor (ground state Sm<SUP>3+</SUP> ion). As the concentration of Sm<SUP>3+</SUP> ions increases the decay time of <SUP>4</SUP>G<SUB>5/2</SUB> state decreases. The well-known Inokuti-Hirayama (IH) model was used for fitting the non-exponential decay curves where S = 6 indicates that energy transfer process is of dipole-dipole type. Hence, in the present work, intense transition of <SUP>4</SUP>G<SUB>5/2</SUB> → <SUP>6</SUP>H<SUB>7/2</SUB> (601nm) is found to be suitable for reddish-orange laser emission. CIE chromaticity diagram has been performed for verifying the results of fluorescence in visible laser applications at 601nm.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

      • SCISCIESCOPUS
      • KCI등재후보

        Tumor-like Presentation of Tubercular Brain Abscess: Case Report

        Karki, Dan B.,Gurung, Ghanashyam,Sharma, Mohan R.,Shrestha, Ram K.,Sayami, Gita,Sedain, Gopal,Shrestha, Amina,Ghimire, Ram K. Korean Society of Magnetic Resonance in Medicine 2015 Investigative Magnetic Resonance Imaging Vol.19 No.4

        A 17-year-old girl presented with complaints of headache and decreasing vision of one month's duration, without any history of fever, weight loss, or any evidence of an immuno-compromised state. Her neurological examination was normal, except for papilledema. Laboratory investigations were within normal limits, except for a slightly increased Erythrocyte Sedimentation Rate (ESR). Non-contrast computerized tomography of her head revealed complex mass in left frontal lobe with a concentric, slightly hyperdense, thickened wall, and moderate perilesional edema with mass effect. Differential diagnoses considered in this case were pilocytic astrocytoma, metastasis and abscess. Magnetic resonance imaging (MRI) obtained in 3.0 Tesla (3.0T) scanner revealed a lobulated outline cystic mass in the left frontal lobe with two concentric layers of T2 hypointense wall, with T2 hyperintensity between the concentric ring. Moderate perilesional edema and mass effect were seen. Post gadolinium study showed a markedly enhancing irregular wall with some enhancing nodular solid component. No restricted diffusion was seen in this mass in diffusion weighted imaging (DWI). Magnetic resonance spectroscopy (MRS) showed increased lactate and lipid peaks in the central part of this mass, although some areas at the wall and perilesional T2 hyperintensity showed an increased choline peak without significant decrease in N-acetylaspartate (NAA) level. Arterial spin labelling (ASL) and dynamic susceptibility contrast (DSC) enhanced perfusion study showed decrease in relative cerebral blood volume at this region. These features in MRI were suggestive of brain abscess. The patient underwent craniotomy with excision of a grayish nodular lesion. Abundant acid fast bacilli (AFB) in acid fast staining, and epithelioid cell granulomas, caseation necrosis and Langhans giant cells in histopathology, were conclusive of tubercular abscess. Tubercular brain abscess is a rare manifestation that simulates malignancy and cause diagnostic dilemma. MRI along with MRS and magnetic resonance perfusion studies, are powerful tools to differentiate lesions in such equivocal cases.

      • Evaluation of seismic strengthening techniques for non-ductile soft-story RC frame

        Karki, Prajwol,Oinam, Romanbabu M.,Sahoo, Dipti Ranjan Techno-Press 2020 Advances in concrete construction Vol.9 No.4

        Open ground story (OGS) reinforced concrete (RC) buildings are vulnerable to the complete collapse or severe damages under seismic actions. This study investigates the effectiveness of four different strengthening techniques representing the local and global modifications to improve the seismic performance of a non-ductile RC OGS frame. Steel caging and concrete jacketing methods of column strengthening are considered as the local modification techniques, whereas steel bracing and RC shear wall systems are selected as the global strengthening techniques in this study. Performance-based plastic design (PBPD) approach relying on energy-balance concept has been adopted to determine the required design force demand on the strengthening elements. Nonlinear static and dynamic analyses are carried out on the numerical models of study frames to assess the effectiveness of selected strengthening techniques in improving the seismic performance of OGS frame.. Strengthening techniques based on steel braces and RC shear wall significantly reduced the peak interstory drift response of the OGS frame. However, the peak floor acceleration of these strengthened frames is amplified by more than 2.5 times as compared to that of unstrengthened frame. Steel caging technique of column strengthening resulted in a reasonable reduction in the peak interstory drift response without substantial amplification in peak floor acceleration of the OSG frame.

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