• Title/Summary/Keyword: phase-contrast

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A Study on GUI Program Development for Steam Tracing System Selection (스팀 트레이싱 시스템 사양 선정 GUI 프로그램 개발에 관한 연구)

  • Choi, Yo Han;Lee, Kwang-Hee;Lee, Chul-Hee;Park, Gwang Ho
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.20 no.4
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    • pp.94-105
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    • 2021
  • A graphical user interface (GUI) program for steam tracing system selection was developed by using a theoretical model. We derived the model on the basis of the one-dimensional heat transfer theory of conduction and convection through a composite wall. Computational fluid dynamics (CFD) and experiments were performed for validation at steam temperatures of 120.4[℃] and 158.9[℃]. The temperature of a pipe's outer surface obtained through CFD matched well with that predicted by the proposed model for both conditions. By contrast, the experiment results showed a small error at 120.4[℃] and a large error at 158.9[℃] because of the melting of the heat transfer compound and water phase transition. Thus, the steam temperature range of the proposed model is below 120.4[℃].

Synthesis and Liquid Crystalline Properties of the Compounds Consisting of a Schiff Base Type Mesogen and a Dyad Type Aromatic Ester Structure Interconnected Through the Central Hexamethylene Spacer

  • Jung-Il Jin;Hyo-Seok Kim;Jin-Wook Shin;Bong Young Chung;Byung-Wook Jo
    • Bulletin of the Korean Chemical Society
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    • v.11 no.3
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    • pp.209-214
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    • 1990
  • A series of compounds consisting of 4'-oxybenzylidene-4-n-butylaniline, a mesogen, and a p-substituted phenoxyterephthaloyl structure a non-mesogen, interconnected through a central hexamethylene spacer were synthesized and their thermal behavior and liquid crystallinity were studied. p-Substituents included in this study are H, Cl, CN, $NO_2,\;n-C_4H_9O$ and phenyl groups. The compounds having phenyl and $n-C_4H_9O$ substituents are enantiotropic and form smectic-A(SA) and nematic (N) phases. The compound with $NO_2$ substituent is monotropic and forms only a nematic phase on heating the solid, whereas it forms nematic as well as $S_A$ phases on cooling the isotropic liquid. The rest compounds were found to be non-liquid crystalline. This is in great contrast to the fact that the monomesogenic model compound 4'-n-hexyloxybenzylidine-4-n-butylaniline forms $S_B,\;S_C,\;S_A$ and N phases enantiotropically.

A Computer-Aided Diagnosis of Brain Tumors Using a Fine-Tuned YOLO-based Model with Transfer Learning

  • Montalbo, Francis Jesmar P.
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.14 no.12
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    • pp.4816-4834
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    • 2020
  • This paper proposes transfer learning and fine-tuning techniques for a deep learning model to detect three distinct brain tumors from Magnetic Resonance Imaging (MRI) scans. In this work, the recent YOLOv4 model trained using a collection of 3064 T1-weighted Contrast-Enhanced (CE)-MRI scans that were pre-processed and labeled for the task. This work trained with the partial 29-layer YOLOv4-Tiny and fine-tuned to work optimally and run efficiently in most platforms with reliable performance. With the help of transfer learning, the model had initial leverage to train faster with pre-trained weights from the COCO dataset, generating a robust set of features required for brain tumor detection. The results yielded the highest mean average precision of 93.14%, a 90.34% precision, 88.58% recall, and 89.45% F1-Score outperforming other previous versions of the YOLO detection models and other studies that used bounding box detections for the same task like Faster R-CNN. As concluded, the YOLOv4-Tiny can work efficiently to detect brain tumors automatically at a rapid phase with the help of proper fine-tuning and transfer learning. This work contributes mainly to assist medical experts in the diagnostic process of brain tumors.

Effect of Neuromuscular Electrical Stimulation Combined with Traditional Dysphagia Rehabilitation on Masseter Muscle Thickness and Bite Force in Stroke with Dysphagia Patient

  • Lee, Myunglyeol;Lee, Kuija;Kim, Jinuk
    • Journal of International Academy of Physical Therapy Research
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    • v.12 no.2
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    • pp.2365-2369
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    • 2021
  • Background: Patients with dysphagia after stroke are treated with neuromuscular electrical stimulation (NMES), but its effect on masseter muscle thickness and bite force in the oral phase is not well known. Objectives: To investigated the effect of NMES on masseter muscle thickness and occlusal force in patients with dysphagia after stroke. Design: Two group, pre-post design. Methods: In this study, 25 patients with dysphagia after stroke were recruited and allocated to either the experimental or the control groups. Patients in the experimental group were treated with NMES to the masseter muscle at the motor level for 30 minutes and were additionally treated with traditional swallowing rehabilitation for 30 minutes. In contrast, patients in the control group were only treated with traditional swallowing rehabilitation for 30 minutes. Masseter muscle thickness was measured using ultrasonography before and after intervention, and bite force was measured using an bite force meter. Results: The experimental group showed significant improvement in masseter muscle thickness and bite force compared to the control group. Conclusion: NMES combined with traditional dysphagia rehabilitation is effective in improving masseter muscle thickness and bite force in patients with dysphagia after stroke.

Development of a Lightweight Prediction Model of Fuel Injection Rates from High Pressure Fuel Injectors (고압 인젝터의 분사율 예측을 위한 경량 모델 개발)

  • Lee, Sanggwon;Bae, Gyuhan;Atac, Omer Faruk;Moon, Seoksu;Kang, Jinsuk
    • Journal of ILASS-Korea
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    • v.25 no.4
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    • pp.188-195
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    • 2020
  • To meet stringent emission regulations of automotive engines, fuel injection control techniques have advanced based on reliable and fast computing prediction models. This study aims to develop a reliable lightweight prediction model of fuel injection rates using a small number of input parameters and based on simple fluid dynamic theories. The prediction model uses the geometry of the injector nozzle, needle motion data, injection conditions and the fuel properties. A commercial diesel injector and US No. 2 diesel were used as the test injector and fuel, respectively. The needle motion data were measured using X-ray phase-contrast imaging technique under various fuel injection pressures and injection pulse durations. The actual injector rate profiles were measured using an injection rate meter for the validation of the model prediction results. In the case of long injection durations with the steady-state operation, the model prediction results showed over 99 % consistency with the measurement results. However, in the case of short injection cases with the transient operation, the prediction model overestimated the injection rate that needs to be further improved.

Isolation of four unrecorded yeasts in the family Filobasidiaceae from soil in Korea

  • Maeng, Soohyun;Park, Yuna;Srinivasan, Sathiyaraj
    • Journal of Species Research
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    • v.10 no.4
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    • pp.350-355
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    • 2021
  • In 2020, 11 Basidiomycetous yeast strains were isolated from soil samples collected from the forests of Namhansanseong in Korea. Among them, seven species were reported, but four species were unreported in Korea. To identify wild yeasts, pairwise sequence comparisons of D1/D2 domain of the 26S rRNA were performed using Basic Local Alignment Search Tool (BLAST). The cell morphologies and assimilation test are observed by phase contrast microscope and API 20C AUX kit, respectively. The 11 strains were assigned to the genera Rhodotorula (4 strains) of the order Sporidiobolales of the class Microbotryomycetes; and Cryptococcus(2 strains), Goffeauzyma (1 strains), Naganishia (2 strains) of the order Filobasidiales and Saitozyma (2 strains) of the order Tremellales of the class Tremellomycetes in the phylum Basidiomycota. The unreported yeast strains Cryptococcus gastricus 20n5-2, Goffeauzyma gilvescens 20n2-7, Naganishia adeliensis 20n8-1, and Naganishia friedmannii 20n24-1 belong to the family Filobasidiaceae. All strains had oval shaped cells and cream-colored colonies cultured on on YM agar for 3 days. In this study, we focus on the description of four unreported yeast species in Korea.

Isolation and characterization of four unrecorded wild yeasts from the soils of Republic of Korea in winter

  • Yuna Park;Soohyun Maeng;Sathiyaraj Srinivasan
    • Journal of Species Research
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    • v.12 no.3
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    • pp.197-202
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    • 2023
  • The purpose of this study was to isolate and identify wild yeasts from the soil collected in Gwangju and Pocheon City, Gyeonggi Province, Republic of Korea. Among 10 strains, six strains were already reported, but four strains were unrecorded in Republic of Korea. To identify wild yeast strains, pairwise sequence comparisons of the D1/D2 region of the 26S rRNA gene sequence were performed using Basic Local Alignment Search Tool (BLAST). The cell morphologies were observed by phase contrast microscope and assimilation tests were carried out using API 20C AUX kit. The 10 strains were assigned to the phyla Basidiomycota (8 strains) and Ascomycota (2strains). The unrecorded four yeast strains, NH33, NH19, NH20, and YP416, belong to the phylum Basidiomycota and the genera Buckleyzyma, Leucosporidium, Holtermanniales, and Mrakia, respectively. All strains had oval-shaped and polar budding cells. In this research, the morphological and biochemical properties of four unreported yeast species were characterized intensively, which were not officially reported in Korea.

The Impact of COVID-19 Pandemic on Stock Prices: An Empirical Study of State-Owned Enterprises in Indonesia Stock Exchange

  • MANGINDAAN, Joanne Valesca;MANOSSOH, Hendrik;WALANGITAN, Olivia Fransiske Christine
    • The Journal of Asian Finance, Economics and Business
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    • v.9 no.3
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    • pp.337-346
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    • 2022
  • This study explores the impact of the COVID-19 pandemic on the stock prices of state-owned enterprises listed on the Indonesia Stock exchange. The impact of the pandemic is analyzed based on different pandemic phases and the corresponding government pandemic interventions to curb the disease. This study analyzes 6 pandemic event dates, covering the time period from January 2020 to February 2021. A total of 20 state-owned enterprises are included as the sample of this study. Test of difference is employed to compare the stock prices of the state-owned enterprises before and after each pandemic event date. In general, this study confirms the adverse impact of the COVID-19 pandemic on the stock prices, especially the event in 2020, although some variations do exist. The results of the study reveal a significant decrease in the stock prices of the state-owned enterprises after the announcement of the first confirmed COVID-19 cases, the announcement of COVID-19 as a global pandemic, the imposing of Large Scale Social Restriction (PSBB I and PSBB II). In contrast, the stock prices increase after the imposing of a new normal policy and the imposing of Public Activity Restriction (PPKM). This study also documents that the effect of the pandemic may vary based on the pandemic phase.

Thermal Stability and Weight Reduction of Al0.75V2.82CrZr Refractory High Entropy Alloy Prepared Via Mechanical Alloying (기계적 합금화를 이용한 Al0.75V2.82CrZr 내화 고엔트로피 합금의 경량화 및 고온 열안정성 연구)

  • Minsu Kim;Hansung Lee;Byungmin Ahn
    • Journal of Powder Materials
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    • v.30 no.6
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    • pp.478-483
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    • 2023
  • High-entropy alloys (HEAs) are characterized by having five or more main elements and forming simple solids without forming intermetallic compounds, owing to the high entropy effect. HEAs with these characteristics are being researched as structural materials for extreme environments. Conventional refractory alloys have excellent high-temperature strength and stability; however, problems occur when they are used extensively in a high-temperature environment, leading to reduced fatigue properties due to oxidation or a limited service life. In contrast, refractory entropy alloys, which provide refractory properties to entropy alloys, can address these issues and improve the high-temperature stability of the alloy through phase control when designed based on existing refractory alloy elements. Refractory high-entropy alloys require sufficient milling time while in the process of mechanical alloying because of the brittleness of the added elements. Consequently, the high-energy milling process must be optimized because of the possibility of contamination of the alloyed powder during prolonged milling. In this study, we investigated the high-temperature oxidation behavior of refractory high-entropy alloys while optimizing the milling time.

Enhanced CT-image for Covid-19 classification using ResNet 50

  • Lobna M. Abouelmagd;Manal soubhy Ali Elbelkasy
    • International Journal of Computer Science & Network Security
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    • v.24 no.1
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    • pp.119-126
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    • 2024
  • Disease caused by the coronavirus (COVID-19) is sweeping the globe. There are numerous methods for identifying this disease using a chest imaging. Computerized Tomography (CT) chest scans are used in this study to detect COVID-19 disease using a pretrain Convolutional Neural Network (CNN) ResNet50. This model is based on image dataset taken from two hospitals and used to identify Covid-19 illnesses. The pre-train CNN (ResNet50) architecture was used for feature extraction, and then fully connected layers were used for classification, yielding 97%, 96%, 96%, 96% for accuracy, precision, recall, and F1-score, respectively. When combining the feature extraction techniques with the Back Propagation Neural Network (BPNN), it produced accuracy, precision, recall, and F1-scores of 92.5%, 83%, 92%, and 87.3%. In our suggested approach, we use a preprocessing phase to improve accuracy. The image was enhanced using the Contrast Limited Adaptive Histogram Equalization (CLAHE) algorithm, which was followed by cropping the image before feature extraction with ResNet50. Finally, a fully connected layer was added for classification, with results of 99.1%, 98.7%, 99%, 98.8% in terms of accuracy, precision, recall, and F1-score.