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Honggi Ahn,Sun Ju Kim,Seungyoung Kang,Junghun Han,Sung Oh Hwang,Kyoung-Chul Cha,Sejung Yang 대한의용생체공학회 2023 Biomedical Engineering Letters (BMEL) Vol.13 No.4
High-quality cardiopulmonary resuscitation (CPR) is the most important factor in promoting resuscitation outcomes; therefore,monitoring the quality of CPR is strongly recommended in current CPR guidelines. Recently, transesophageal echocardiography(TEE) has been proposed as a potential real-time feedback modality because physicians can obtain clearechocardiographic images without interfering with CPR. The quality of CPR would be optimized if the myocardial ejectionfraction (EF) could be calculated in real-time during CPR. We conducted a study to derive a protocol to detect systole anddiastole automatically and calculate EF using TEE images acquired from patients with cardiac arrest. The data were supplementedusing thin-plate spline transformation to solve the problem of insufficient data. The deep learning model wasconstructed based on ResUNet + + , and a monogenic filtering method was applied to clarify the ventricular boundary. Theperformance of the model to which the monogenic filter was added and the existing model was compared. The left ventriclewas segmented in the ME LAX view, and the left and right ventricles were segmented in the ME four-chamber view. Inmost of the results, the performance of the model to which the monogenic filter was added was high, and the difference wasvery small in some cases; but the performance of the existing model was high. Through this learned model, the effect ofCPR can be quantitatively analyzed by segmenting the ventricle and quantitatively analyzing the degree of contraction ofthe ventricle during systole and diastole.
Two Phase Flow Boiling Heat Transfer of R410A Inside Horizontal Aluminum Multiport Tube
Jong-Taek Oh(오종택),Nguyen Ba Chien,Pham Quang Vu,Kwang-Il Choi(최광일),Honggi Cho(조홍기),Taehun Kim(김태헌) 대한기계학회 2015 대한기계학회 춘추학술대회 Vol.2015 No.11
Two phase flow boiling heat transfer coefficient of R410A inside multiport tube were investigated in this study. The experimental data were conducted in horizontal aluminum tubes with the hydraulic diameter of 1.14 ㎜. The testing conditions were performed with the mass fluxes from 50 to 150 ㎏/㎡s, the heat fluxes from 3 to 6 ㎾/㎡, the saturation temperature of 6℃ and the vapor quality from 0.1 to dry-out. The effects of mass flux, heat flux on the heat transfer coefficient were analyzed. The experimental data were also compared with some well-known heat transfer coefficient correlations.
Vu, Pham-Quang,Choi, Kwang-Il,Oh, Jong-Taek,Cho, Honggi World Scientific Publishing Co. Pte. Ltd. 2017 International Journal of Air-Conditioning and Refr Vol.25 No.2
<P>The condensation heat transfer coefficients and pressure drops of R410A and R22 flowing inside a horizontal aluminum multiport mini-channel tube having 18 channels are investigated. Experimental data are presented for the range of vapor quality from 0.1 to 0.9, mass flux from 50 to 500<TEX>$ \,$</TEX>kg/m<SUP>2</SUP>s, heat flux from 3 to 15<TEX>$ \,$</TEX>kW/m<SUP>2</SUP> and the saturation temperature at 48<TEX>$ ^{\circ }$</TEX>C. The pressure drop across the test section was directly measured by a differential pressure transducer. At a small scale, the noncircular cross-sections can enhance the effect of the surface tension. The average heat transfer coefficient increased with the increase of vapor quality, mass flux and heat flux. Under the same test conditions, the heat transfer coefficients of R22 are higher than those for R410A, the pressure drops for R410A are 7-19% lower than those of R22. The lower pressure drop of R410A has an important advantage as an alternative working fluid for R22 in air-conditioning and heat pump systems.</P>
Experimental investigation of flow condensation in the micro-fin tube
Pham Quang Vu,Kwang-Il Choi,Jong-Taek Oh,Honggi Cho 대한설비공학회 2018 대한설비공학회 학술발표대회논문집 Vol.2018 No.6
This study experimentally investigated the flow condensation heat transfer characteristics of R410A, R22, R32 and R290 (propane) inside a 7mm OD micro-fin copper tube. The flow condensation heat transfer was measured at mass fluxes of 50 to 380kg/m2s; heat flux of 3 and 12kW/m2; and a saturation temperature of 48oC. The variations of refrigerant mass flux, heat flux with condensation heat transfer performances were obtained. The comparison shows that the heat transfer coefficients of propane are higher than those for R32, R22 and R410A. The different thermophysical properties of the four refrigerants result in the heat transfer coefficient differences.
최광일(Kwang-Il Choi),Pham Quang Vu,오종택(Jong-Taek Oh),조홍기(Honggi Cho),김태현(Taehun Kim),김중호(Jungho Kim),이창선(Changseon Lee) 대한설비공학회 2013 대한설비공학회 학술발표대회논문집 Vol.2013 No.11
An experimental investigation of condensation heat transfer of R410A was carried out for horizontal micro-fin tubes of 6.61 mm and 7.45 mm inner diameter in this study. The heat transfer coefficient and pressure drop were measured under the following conditions: the saturation temperature was at 48˚C, the mass flux ranged from 200 to 320 kg/m²s, the heat flux ranged from 9 to 12 kg/m²s, the quality of vapor reached to an unit and the length of test section was 1.2m. The effects of mass flux, heat flux and inner diameter on heat transfer coefficient were evaluated. The heat transfer coefficient and pressure drop were also compared using some existing correlations.