Obesity and hypertension in children and adolescents

Jeong Sooin,Kim Sung Hye 대한고혈압학회 2024 Clinical Hypertension Vol.30 No.-

As childhood obesity rates increase worldwide, the prevalence of obesity-related hypertension is also on the rise. Obesity has been identified as a significant risk factor for hypertension in this age group. National Health Surveys and meta-analyses show increasing trends in obesity and pediatric hypertension in obese children. The diagnosis of hypertension in children involves percentiles relative to age, sex, and height, unlike in adults, where absolute values are considered. Elevated blood pressure (BP) in childhood is consistently associated with cardiovascular disease in adulthood, emphasizing the need for early detection and intervention. The pathogenesis of hypertension in obesity involves multiple factors, including increased sympathetic nervous system activity, activation of the renin-angiotensin-aldosterone system (RAAS), and renal compression due to fat accumulation. Obesity disrupts normal RAAS suppression and contributes to impaired pressure natriuresis and sodium retention, which are critical factors in the development of hypertension. Risk factors for hypertension in obesity include degree, duration, and distribution of obesity, patient age, hormonal changes during puberty, high-sodium diet, sedentary lifestyle, and socioeconomic status. Treatment involves lifestyle changes, with weight loss being crucial to lowering BP. Medications such as angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers may be considered first, and surgical approaches may be an option for severe obesity, requiring tailored antihypertensive medications that consider individual pathophysiology to avoid exacerbating insulin resistance and dyslipidemia. As childhood obesity rates increase worldwide, the prevalence of obesity-related hypertension is also on the rise. Obesity has been identified as a significant risk factor for hypertension in this age group. National Health Surveys and meta-analyses show increasing trends in obesity and pediatric hypertension in obese children. The diagnosis of hypertension in children involves percentiles relative to age, sex, and height, unlike in adults, where absolute values are considered. Elevated blood pressure (BP) in childhood is consistently associated with cardiovascular disease in adulthood, emphasizing the need for early detection and intervention. The pathogenesis of hypertension in obesity involves multiple factors, including increased sympathetic nervous system activity, activation of the renin-angiotensin-aldosterone system (RAAS), and renal compression due to fat accumulation. Obesity disrupts normal RAAS suppression and contributes to impaired pressure natriuresis and sodium retention, which are critical factors in the development of hypertension. Risk factors for hypertension in obesity include degree, duration, and distribution of obesity, patient age, hormonal changes during puberty, high-sodium diet, sedentary lifestyle, and socioeconomic status. Treatment involves lifestyle changes, with weight loss being crucial to lowering BP. Medications such as angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers may be considered first, and surgical approaches may be an option for severe obesity, requiring tailored antihypertensive medications that consider individual pathophysiology to avoid exacerbating insulin resistance and dyslipidemia.

Rotor Blade Sweep Effect on the Performance of a Small Axial Supersonic Impulse Turbine

Sooin Jeong,Byoungik Choi,Kuisoon Kim 한국항공우주학회 2015 International Journal of Aeronautical and Space Sc Vol.16 No.4

In this paper, a computational study was conducted in order to investigate the rotor blade sweep effect on the aerodynamics of a small axial supersonic impulse turbine stage. For this purpose, three-dimensional unsteady RANS simulations have been performed with three different rotor blade sweep angles (-15°, 0°, +15°) and the results were compared with each other. Both NTG (No tip gap) and WTG (With tip gap) models were applied to examine the effect on tip leakage flow. As a result of the simulation, the positive sweep model (+15°) showed better performance in relative flow angle, Mach number distribution, entropy rise, and tip leakage mass flow rate compared with no sweep model. With the blade static pressure distribution result, the positive sweep model showed that hub and tip loading was increased and midspan loading was reduced compared with no sweep model while the negative sweep model (-15°) showed the opposite result. The positive sweep model also showed a good aerodynamic performance around the hub region compared with other models. Overall, the positive sweep angle enhanced the turbine efficiency.

Rotor Blade Sweep Effect on the Performance of a Small Axial Supersonic Impulse Turbine

Jeong, Sooin,Choi, Byoungik,Kim, Kuisoon The Korean Society for Aeronautical and Space Scie 2015 International Journal of Aeronautical and Space Sc Vol.16 No.4

In this paper, a computational study was conducted in order to investigate the rotor blade sweep effect on the aerodynamics of a small axial supersonic impulse turbine stage. For this purpose, three-dimensional unsteady RANS simulations have been performed with three different rotor blade sweep angles ($-15^{\circ}$, $0^{\circ}$, $+15^{\circ}$) and the results were compared with each other. Both NTG (No tip gap) and WTG (With tip gap) models were applied to examine the effect on tip leakage flow. As a result of the simulation, the positive sweep model ($+15^{\circ}$) showed better performance in relative flow angle, Mach number distribution, entropy rise, and tip leakage mass flow rate compared with no sweep model. With the blade static pressure distribution result, the positive sweep model showed that hub and tip loading was increased and midspan loading was reduced compared with no sweep model while the negative sweep model ($-15^{\circ}$) showed the opposite result. The positive sweep model also showed a good aerodynamic performance around the hub region compared with other models. Overall, the positive sweep angle enhanced the turbine efficiency.

충동형 초음속 터빈의 노즐-로터 축간극에 따른 성능변화 연구

정수인(Sooin Jeong),김귀순(Kuisoon Kim),정은환(Eunhwan Jeong) 한국추진공학회 2010 한국추진공학회 학술대회논문집 Vol.2010 No.11

부분흡입형 초음속 터빈의 노즐과 1단 로터 사이의 축방향 간극이 터빈의 단 성능과 유동장에 어떤 영향을 미치는지 알아보기 위해 터빈에 대한 3차원 유동해석을 수행하고 그 결과를 분석하였다. 상용 유동해석 프로그램 FLUENTTM를 사용하였으며 다섯 가지 경우의 축간극에 대해 계산을 하였다. 노즐-로터 축간극이 팁 누설 유량의 증가와 로터 출구의 유동각에 영향을 주는 것을 확인하였다. We performed three-dimensional CFD analysis to investigate the effect of the nozzle-rotor axial gap of a partial admission supersonic turbine on the stage performance and the flow field. The computations are conducted for five axial gaps using flow analysis program, FLUENTTM. The results show that the axial gap between nozzle and rotor give the effect on the mass flow rates of tip leakage and the flow angle at the rotor outlet.

초음속 터빈의 로터 블레이드 스윕 효과에 대한 수치적 연구

정수인(Sooin Jeong),정은환(Eunhwan Jeong),김귀순(Kuisoon Kim) 한국추진공학회 2011 한국추진공학회 학술대회논문집 Vol.2011 No.11

본 연구에서는 액체로켓엔진의 터보펌프용 초음속 터빈 로터 블레이드에 스윕 각도 ±15°를 적용하여 전방스윕(FSW), 후방스윕(BSW)모델의 유동형태 및 성능을 기준모델(NSW)과 비교하여 스윕 적용의 효과를 살펴보았다. 3차원 Navier-Stokes 유동해석에는 상용 코드인 FLUENT 6.3 Parallel을 사용하였다. BSW 모델은 기준 모델(NSW)에 비해 팁 간극으로 빠져나가는 누설 손실량을 줄이는데 효과가 있었고 정효율 증가에도 영향을 미쳤다. In this study, we performed three-dimensional CFD analysis to investigate the effect of the rotor blade sweep of a partial admission supersonic turbine on the stage performance and the flow field. The computations are conducted for three different sweep cases, No sweep(NSW), Backward sweep(BSW), and Forward sweep(FSW), using flow analysis program, FLUENT<SUP>TM</SUP> 6.3 Parallel. The results show that BSW model give the effect on the reducing of mass flow rates of tip leakage and the increasing of t-to-s efficiency.

Common Data Model-based Analysis of Selective Leukoreduction Protocol Compliance at Three Hospitals

Choi Sooin,Choi Soo Jeong,Shin Jeong Won,Yoon Young Ahn 대한진단검사의학회 2023 Annals of Laboratory Medicine Vol.43 No.2

Background: The selective leukoreduction protocol (SLP) is limited in that patients who require it can be overlooked. We estimated SLP compliance (SLPC) using the Observational Medical Outcomes Partnership common data model (CDM). Methods: Patients were classified into eight groups: pre- and post-hematology disease (A and B), pre- and post-solid organ transplantation (C and D), solid cancer (E), immunodeficiency (F), anticancer therapy (G), and cardiovascular surgery (H). We examined the red blood cell (RBC) transfusion history from three hospital datasets comprising approximately three million patients over 20 years using CDM-based analysis. SLPC was calculated as the percentage of patients who received only leukoreduced RBCs in total patients transfused RBCs. Results: In total, 166,641 patients from three hospitals were enrolled in this study. From 2001 to 2021, SLPC in all groups, except H, tended to increase, although there were differences among the hospitals. Based on the most recent values (2017–2021), the SLPC in groups A, B, D, and G was maintained at ≥75% until 1,095 days before or after diagnosis or treatment. Groups E, F, and H had < 50% SLPC one day after diagnosis and treatment. Conclusions: CDM analysis supports the review of large datasets for SLPC evaluation. Although SLPC tended to improve in most patient groups, additional education and monitoring are needed for groups that continue to show low SLPC.

비정상 해석을 이용한 노즐-로터 축간극 거리에 따른 초음속 터빈 내의 성능특성 연구

정수인(Sooin Jeong),최병익(Byoung-ik Choi),김귀순(Kuisoon Kim) 한국추진공학회 2014 한국추진공학회 학술대회논문집 Vol.2014 No.12

본 연구에서는 초음속 충동형 터빈의 노즐과 1단 로터 사이 축 간극 거리를 달리하며 3차원 비정상 유동해석을 수행하고 초음속 터빈의 성능 특성을 분석하였다. 수치계산은 로터 블레이드 높이의 약 6%, 10%, 20%, 30%에 해당하는 터빈의 축 방향 간극 총 네 가지 경우에 대하여 이루어졌다. 3차원 비정상 Navier-Stokes 유동해석에는 상용코드인 FLUENT를 사용하였다. 계산결과는 기존의 초음속 터빈효율 경향과 잘 일치하였으며 특정 축 간극 구간에서 효율의 급격한 감소를 보이고 그 이후에는 큰 변화가 없는 구간이 존재함을 확인하였다. In this study, three-dimensional URANS simulation has been performed to analyze the effect of the nozzle-rotor axial gap spacing of a supersonic impulse turbine on turbine performance. The computations are conducted for four axial gap cases using flow analysis program, FLUENTTM. The results show a good agreement with previous studies and have been found that the turbine efficiency decreases drastically in certain range.

최적화기법을 이용한 초음속 충동형 터빈 노즐의 비대칭 설계

정수인(Sooin Jeong),최병익(Byoungik Choi),정은환(Eunhwan Jeong),김귀순(Kuisoon Kim) 한국추진공학회 2011 한국추진공학회 학술대회논문집 Vol.2011 No.5

본 연구에서는 초음속 충동형 터빈의 노즐에서 나타나는 유동의 과소·과대팽창 문제를 최적화 기법을 이용하여 비대칭형상을 포함해 설계함으로써 개선시키고자 하였다. 노즐 형상 설계를 위해 8개의 설계변수를 설정하였으며 목적함수로는 후류 영역 출구까지의 정효율이 최대가 되도록 하였다. 최적화에는 iSIGHT-FD가 사용되었으며 근사최적화를 위한 방법으로는 Radial Basis Function을 이용하였다. 노즐유동의 계산에는 상용 코드인 FLUENT 6.3을 사용하였으며 개선된 노즐의 정효율은 기존 대비 1.35% 증가하였고 손실계수는 19.85% 감소하였다. In this paper, the nozzle design with asymmetric configuration using the optimal method is used in order to improve the under- and over-expansion problem of the flow at the supersonic turbine nozzle. For the design of nozzle contour, 8 design variables are selected and the total-to-static efficiency from the nozzle inlet to the wake outlet is considered as the objective function to be maximized. The Fluent6.3 and the iSIGHT-FD program are used for calculation of nozzle flow and design optimization respectively. RBF(Radial Basis Function) method is chosen for approximate optimization algorithm. It is shown that the static efficiency of improved nozzle design increases 1.35% and loss coefficient decreases 19.85% as compared to baseline design.

스윕 각이 적용된 부분 흡입형 초음속 축류 터빈의 정상, 비정상 공력 특성에 관한 수치적 연구

정수인(Sooin Jeong),김귀순(Kuisoon Kim) 한국추진공학회 2012 한국추진공학회 학술대회논문집 Vol.2012 No.5

본 논문에서는 부분 흡입형 초음속 터빈의 로터 블레이드에 ±15°의 스윕 각도를 적용하여 그에 의한 효과와 공력 특성을 살펴보기 위해 정상상태 유동해석과 비정상상태 유동해석을 동시에 수행하고 그 결과를 비교해 보았다. 3차원 Navier-Stokes 유동해석에는 상용 코드인 FLUENT 6.3 Parallel을 사용하였다. 모든 계산 케이스들에서 정상상태 유동해석에 비해 비정상상태의 경우가 손실이 더욱 크게 나오는 결과를 나타내었다. 후방스윕(BSW)모델은 기준모델(NSW)에 비해 팁 간극으로 빠져나가는 누설 손실량을 줄이는데 큰 효과가 있었고 비정상상태 유동 해석에서는 로터 출구면 정효율의 증가현상이 더욱 뚜렷하게 나타났다. Steady and unsteady three-dimensional RANS simulations have been performed on partial admission supersonic axial turbine having backward/forward sweep angles(±15°) and the results are compared with each other. The objective of this paper is to study the effect of unsteadiness on turbine flow characteristics and performances. The all results indicated that the losses of unsteady simulations were greater than those of steady cases. It was also shown that BSW model give the effect on the reducing of mass flow rates of tip leakage. In unsteady simulation, the increase of t-to-s efficiency at Rotor Out plane was observed more clearly.

국소 스윕을 적용한 충동형 로터 블레이드가 부분분사형 초음속 터빈의 성능에 미치는 영향

정수인(Sooin Jeong),최병익(Byoungik Choi),이항기(Hanggi Lee),김귀순(Kuisoon Kim) 한국추진공학회 2018 한국추진공학회 학술대회논문집 Vol.2018 No.5