Supersonic turbine stator design using dense gas with numerical method

서종범,한상조 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.9

In recent years, interest in renewable energy as a substitute for power generation using coal has increased. As a next-generation power system, the Organic Rankine cycle (ORC) system, which requires a multi-stage turbine or a supersonic turbine to generate a high power, has been shown to have high potential for such uses. In this paper, a dense gas is chosen as a working fluid and a supersonic nozzle is designed for a supersonic turbine with advantages in terms of cost, power density and layout. Two stators are designed using the Method of characteristics (MOC) for air and dense gas. To validate the numerical model, the nozzle designed for the air is compared to that of a PIV experiment from the open literature, and the results indicate a reasonable agreement. The nozzle for the dense gas is different as that needed for air. Therefore, the modified MOC is applied based on a polytropic assumption. In conclusion, an estimation of the performance is implemented with loss coefficients for a different number of blades. The number of blades is shown to be proportional to the loss coefficient. For example, the case with the biggest numbers of blades is affected the most by the shock effect that occurs at the trailing edge.

의료 초음파 영역

서종범 대한전자공학회 2015 전자공학회지 Vol.42 No.11

Ultrasound imaging and beyond: recent advances in medical ultrasound

서종범,김영선 대한의용생체공학회 2017 Biomedical Engineering Letters (BMEL) Vol.7 No.2

Medical ultrasound represented by ultrasound imaging is generally believed to be well-known area in research, because ultrasound imaging systems has been widely distributed and actively used in the world since the 1960s. The annual world-wide use of ultrasound imaging in practice is already over billions and all pregnant women have been screened with ultrasound in some countries, such as Germany, Norway, Iceland, and Austria for years [1]. In industry, not only portable systems were available since the early 2000s, but also wireless ultrasound imaging transducers cooperating with tablet PCs were introduced in the early 2010s. Accordingly, ultrasound in medicine has been believed relatively low-tech and obsolete research field to general audience.

Non-equilibrium 2상 유동 모델을 적용한 OTEC 터빈의 수치 해석

서종범,이호생,김현주 한국동력기계공학회 2022 동력시스템공학회지 Vol.26 No.6

탄소중립은 거부할 수 없는 시대적 사명으로 떠오르고 있다. 이를 실현하기 위해서는 재생에너지 비중을 확대해야 하며 해양에너지가 대안이 될 수 있다. 해양 에너지 중 하나인 OTEC은 해양 에너지 중 이론적인 잠재력이 가장 크다. 이 중 폐쇄형 OTEC의 경우 터빈에서 2상 유동이 발생할 수 있으며 보다 정확한 설계 및 해석을 위해서는 CFD(Computational Fluid Dynamics)로 모델링할 필요가 있다. 본 연구에서는 열역학적 평형을 가정한 Equilibrium(Eq) 모델 대신 Non-equilibrium(Non-eq) 2상 모델을 적용하였다. 그 결과를 단상, Eq 모델 및 실험 결과와 비교 분석하였다. 또한 GCI 방법을 사용하여 이산화 오류를 추정했다. CFD 시뮬레이션 결과, Non-eq 모델이 단상 및 Eq 모델에 비해 실험값과 가장 유사하였다. 정성적으로는 Non-eq 모델은 스팬방향 50%에서 속도장과 질량분율에서 약간의 차이를 보였다. 결론적으로 실제에 가장 가깝다고 추정되는 모델은 Non-Eq 모델이며, 이에 대한 근거를 정량적, 정성적으로 추정하였다.

High Intensity Focused Ultrasound for Cancer Treatment: Current Agenda and the Latest Technology Trends

서종범,Seo, Jong-Bum The Acoustical Society of Korea 2010 韓國音響學會誌 Vol.29 No.e2

High Intensity Focused Ultrasound (HIFU) is a noninvasive surgical method mainly targeting deeply located cancer tissue. Ultrasound is generated from an extemally located transducer and the beam is focused at the target volume, so that selective damage can be achieved without harm to overlying or surrounding tissues. The mechanism for cell killing can be combination of thermal and cavitational damage. Although cavitation can be an effective means of tissue destruction, the possibility of massive hemorrhage and the unpredictable nature of cavitational events prevent clinical application of cavitation. Hence, thermal damage has been a main focus related to HIFU research. 2D phased array transducer systems allow electronic scanning of focus, multi-foci, and anti-focus with multi-foci, so that HIFU becomes more applicable in clinical use. Currently, lack of noninvasive monitoring means of HIFU is the main factor to limit clinical applications, but development in MRI and Ultrasound Imaging techniques may be able to provide solutions to overcome this problem. With the development of advanced focusing algorithm and monitoring means, complete noninvasive surgery is expected to be implemented in the near future.

신항만 해사 매립 공사시 주변피해영향 평가조사

서종범,김택준,손병현,이규홍,장상용,오광중 대한환경공학회 2008 대한환경공학회 학술발표논문집 Vol.2008 No.12

기계 학습을 이용한 ORC용 터빈 형상 최적화

서종범,변기원,홍선기,이호생,한상조 한국동력기계공학회 2023 동력시스템공학회지 Vol.27 No.6

In this study, our primary objective is to optimize a turbine employed in an Organic Rankine Cycle (ORC) system that harnesses waste heat from a ship. Traditional optimization methods are known to be time-consuming and expensive. To streamline a more practical optimization approach, we have leveraged design of experiment, machine learning, and Latin hypercube sampling. Our experimental design involves varying turbine geometries under different conditions and subsequently creating a machine learning model using the results derived from computational fluid dynamics simulations. Through the utilization of these methodologies, we have succeeded in achieving a turbine that surpasses the turbine isentropic efficiency obtained at the initial design point by 1.3% point.

텔레코칭을 통한 기능적 의사소통 훈련이 발달지체 유아의 자해행동 및 교사의 중재 충실도에 미치는 영향

서종범(Jong-bum Seo),이선희(Surn-hee Lee) 한국교통대학교 미래교육통합연구소 2024 미래교육통합연구 Vol.5 No.-

이 연구는 텔레코칭을 통한 기능적 의사소통 훈련이 발달지체 유아의 자해행동과 교사의 중재 충실도에 미치는 영향을 검증하고자 하였다. 연구 참여 유아는 유치원에 재원 중인 발달지체 유아 1명을 대상으로 기능적 의사소통 훈련과 자해행동 간의 효과를 입증하고자 상황간 중다 간헐 기초선 설계(multiple probe baseline design across settings)를 사용하였다. 중재를 실행한 교사는 행동중재 경험이 없는 신규교사로 전문가의 텔레코칭을 통한 중재 실행평가를 위해 매회기 중재 충실도를 평가하였다. 연구 참여 유아의 자해행동이 자주 발생하는 유치원에서 기능적 행동평가 및 기능적 의사소통 훈련 중재를 실행하였다. 연구결과 첫째, 기능적 의사소통 훈련을 통한 행동 중재는 연구 참여 유아의 자해행동에 효과적이었으며, 중재 종료 후에도 효과가 유지되었다. 둘째, 중재를 실행한 교사의 중재는 중재 계획에 따라 정확하게 실행된 것으로 나타났다. 본 연구는 발달지체 유아의 유치원 생활 중에서 발생하는 행동의 기능을 파악하여 기능적 의사소통 훈련 중재를 적용함으로써 발달지체 유아를 지도하는 유치원 교사들에게 효과적인 중재 방법이 될 수 있음을 시사한다. 또한 행동중재 경험이 부족한 저 경력 교사의 행동 중재 실행 방안에 대해 논의하였다. The purpose this study was to examine the effects of functional communication training via tele-coaching on self-injurious behavior and teacher fidelity to intervention in a toddler with developmental delay. A multiple probe baseline design across settings was used to demonstrate the effect of functional communication training on self-injurious behavior in one toddler with developmental delay enrolled in a preschool. The teacher who implemented the intervention was new to behavioral interventions and received expert telecoaching to assess intervention implementation and Treatment Fidelity at each session. The functional behavioral assessment and functional communication training interventions were implemented in a preschool with a high incidence of self-injurious behavior in participating toddlers. Results: First, the behavioral intervention with functional communication training was effective in reducing the self-injurious behavior of the participating toddler, and the effect was maintained even after the intervention ended. Second, the teachers' interventions were implemented accurately according to the intervention plan. This study suggests that functional communication training interventions can be an effective intervention for preschool teachers working with children with developmental delays by identifying the function of behaviors that occur during the preschool years. The study also discussed how to implement behavioral interventions for low-career teachers who lack experience in behavioral interventions.

복합흡수공정에서 CO₂/NO₂ 동시제거 시 AMP(2-amino-2-methyl-1-propanol)에 Ammonia 첨가가 흡수속도에 미치는 영향

서종범(Jong Beom Seo),최원준(Won Joon Choi),문승재(Seung Jae Moon),이규홍(Gou Hong Lee),오광중(Kwang Joong Oh) 大韓環境工學會 2008 대한환경공학회지 Vol.30 No.12

기존의 연구에서 널리 사용된 흡수제 2-amino-2-methyl-1-propanol (AMP)의 성능 개선을 위해 carbon dioxide (CO₂) 및 nitrogen dioxide (NO₂)의 흡수율이 우수한 ammonia (NH₃)를 첨가하여 평면교반조에서 CO₂, NO₂ 및 CO₂/NO₂의 흡수속도실험을 수행함으로써 반응속도상수를 AMP 단일흡수제와 비교하였다. 30 wt.% AMP에 1, 3, 5 wt.%의 NH₃ 첨가에 따라 흡수속도는 대표적으로 303 K, 1 kPa NO₂ 분압에서 12.6~32.6% 증가되므로 NH₃의 첨가로 반응속도를 향상시켜 공정 효율의 증가를 기대할 수 있을 것으로 예상된다. 또한 30 wt.% AMP에 3 wt.% NH₃ 첨가 수용액의 NO₂ 분압 1 kPa과 CO₂ 분압 15 kPa에서 CO₂/NO₂ 동시 흡수속도는 5.50~6.40×10(-6) kmol m-2 s-1로 NH₃의 CO₂ 및 NO₂에 대한 높은 부하능 및 추가 반응에 기인하여 AMP 단일수용액에 비해 48.2~41.6% 증가하였다. 또한, 화력발전소에서 배출되는 연소배가스 조성과 같이 CO₂ 15 kPa 및 NO₂의 비교적 낮은 분압(1 kPa) 조건에서 NO₂는 AMP에 NH₃ 첨가에 따라 약 2배의 빠른 반응으로 CO₂의 흡수에 큰 영향 없이 NO₂를 동시에 흡수할 수 있을 것으로 기대된다. In this study, a blend of 2-amino-2-methyl-1-propanol (AMP) and ammonia (NH₃) was used to achieve high absorption rates for carbon dioxide (CO₂) as suggested at several literatures. The absorption rates of aqueous AMP and blended AMP+NH₃ solutions with CO₂ and nitrogen dioxide (NO₂) were measured using a stirred-cell reactor at 303 K. The effect of the added NH₃ to enhance absorption characteristics of AMP was studied. The performances were evaluated under various operating conditions. The absorption rates increased following the increase of the concentration of NH₃. The absorption rate of NH₃ blended into 30 wt.% AMP solution with NO₂ at 303 K was 12.6~32.6% higher than that of aqueous AMP solution without NH₃. Also, the addition of 3 wt.% NH₃ to 30 wt.% AMP increased 48.2~41.6% values for the reactions with CO₂ and NO₂ at 303 K. Therefore, it clearly shows that the reaction rate of AMP with CO₂ and NO₂ can be increased by the addition of NH₃.

수치해석을 이용한 20kW EP-OTEC용 터빈 설계

서종범(Jongbeom Seo),김현주(Hyeonju Kim),한상조(S. Han) 한국신재생에너지학회 2015 한국신재생에너지학회 학술대회논문집 Vol.2015 No.11