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RISS 인기검색어
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- 저자 : 전석환(Suk-Hwan Jun) (검색결과 5 건)
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전석환,정인철,정상오,윤형로,Jun, Suk-Hwan,Jeong, In-Cheol,Jung, Sang-O,Yoon, Hyung-Ro 대한의용생체공학회 2009 의공학회지 Vol.30 No.2
The ideal method which measures a blood vessel of senility and degree of arteriosclerosis is to measure compliance of arterial and condition of blood circulation at the periphery. In these days vascular stiffness have been assessed by analyzing PTT (pulse transit time) from ECG and PPG. PTT is that between toe and finger each subject estimated through ECG and PPG signals. Two parameters, which are related to PWV, were tested with the time delay between the finger and toe. PWV is a variation of quantity which is associated with vascular stiffness. These researches which use PTT and PWV don't consider the blood vessel characteristic of an individual. In this current research, we have used with the blood vessel characteristic of an individual. That is an assessment of vascular stiffness using the variation of quantity in PWV with the changes of position in the subject. PWV variation increased as functions of the subject's age. The increase of the PWV variation parameters with age is attributed to the direct decrease of the blood vessel compliance with different position. The quantity of variation estimated by experimental results is that old age's (75.78${\pm}$7.75) case is 113.68% and young age's (26.47${\pm}$2.04) case is 85.69%. We proved and presented about estimation of vascular stiffness of possibility by this result.
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냉각식 액체질량유량계측기에 관한 실험적 연구 및 수치해석의 정확도 검증
최규태(Kyu Tae Choi),전석환(Suk-Hwan Jun),김택영(Taig Young Kim) 대한기계학회 2023 大韓機械學會論文集B Vol.47 No.6
고집적도 차세대-반도체 생산설비의 핵심부품인 냉각식 액체질량유량계측기(cooling type liquid mass flow meter)의 시작품을 제작하여 실험을 수행하였으며, 수치해석과 비교를 통하여 이론의 정확도를 분석하였다. 정밀저울로 계측한 누적 액체질량의 시간에 따른 변화로부터 일관되고 신뢰성이 높은 액체질량유량을 산출하였으며, 센서관을 통한 압력손실의 선형적 변화에 근거하여 이론모델에 도입한 관 유동포물선 속도분포의 타당성을 확인하였다. 수치해석 결과는 실험계측치와 전반적으로 잘 일치하였으나 TEC 냉각부에서는 오차가 상대적으로 크고, 이는 질량유량계측의 기본이 되는 온도차비의 수치해석적예측에 증폭된 오차로 나타난다. 이러한 오차에도 불구하고, 질량유량에 따라 변하는 온도차비의 변화경향은 실험과 동일하므로, 설계변수에 대한 최적화와 다양한 유체에 대한 변환인자 도출에 수치해석을 효과적으로 적용할 수 있다. A prototype of the cooling type liquid mass flow meter (CLMFM), which is a key component in high-density next-generation semiconductor production facilities, was fabricated and tested, and the accuracy of the mathematical theory was verified using numerical analysis. A consistent and highly reliable mass flow rate was obtained using a precision balance based on the slop of the cumulative liquid mass with time. Additionally, the appropriateness of the parabolic velocity profile for sensor tube flow in the theoretical model was verified based on the linearity of the pressure drop with the mass flow rate. Consequently, the numerical results generally match well with the experimental measurements except in the TEC cooling zone where a relatively large error is obtained. This error amplifies that of the temperature difference ratio, which is the basis of the measurement data for the liquid mass flow rate. Despite this defect, the propensity of the varying temperature difference ratio with the mass flow rate is the same as that from the experiment; therefore, numerical analysis can be effectively applied to optimize the design variables and derive conversion factors for various fluids.
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임택균(Taek-Gyun Lim),서광석(Kwang-Seok Seo),정인철(In-Cheol Jeong),전석환(Suk-Hwan Jun),노연식(Yeon-Sik Noh),김응석(Eung-Seok Kim),윤형로(Hyung-Ro Yoon) 대한전기학회 2009 전기학회논문지 Vol.58 No.4
Truncal obesity associated with insulin resistance and metabolic syndrome increase the likelihood of hypertension, various cardiovascular diseases, hyperlipidemia and coronary heart diseases. International Diabetes Federation (IDF) experts recognized that it is necessary to develop the simple diagnostic tool which is applicable to diagnose truncal obesity worldwide, and proposed the method using a waist circumference but there is a limit to estimate subcutaneous fat distribution. However, waist line is also influenced by total fat capacity less than the intra abdominal fat. The more having severe obesity, the more correlation coefficient between waist line and intra abdominal fat is low. Therefore, this thesis defines a new abdominal impedance measurement position and impedance-index to analysis central obesity. This proposes the new model to estimate abdominal obesity using the abdominal impedance-index and CT images acquired from 160 Korean subjects. The proposed model shows that the abdominal fat distribution has a higher correlation than waist line. (Adj R2 = 0.809, 0.667 and 0.687 with abdominal fat area, visceral fat area and subcutaneous fat area respectively).
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최규태(Kyu Tae Choi),류연동(Yeon Dong Ryu),전석환(Suk-Hwan Jun),김유환(Yu-Hwan Kim),한진호(Jin Ho Han),김택영(Taig Young Kim) 대한기계학회 2022 大韓機械學會論文集B Vol.46 No.3
일정한 벽 온도 조건하의 관 유동 대류열전달에 대한 단순이론으로부터 TEC를 사용한 냉각식 액체질량유량 계측이론을 추론하여 제시하였으며, 수치해석을 통하여 상 · 하류 온도 계측위치 간 거리, 관외경, TEC와 관 외피 사이 접촉열저항, 주위온도 등 설계인자의 영향을 평가하고, 지수함수 형태의 수학모델을 정립하였다. 수학모델에 근거하여 최소 및 최대 유량계측 분해능에 한계가 존재함을 확인하였으며, 이러한 한계 영역을 확장하기 위한 설계지침을 제시하였다. 최소 질량유량과 최대 질량유량 계측범위 확장을 위한 설계는 서로 상반되는 경향을 갖는다. 수학모델에 직접 나타나지 않았으나, 주위온도는 입 · 출구 온도차 비의 선형적 변화를 유도하며, 계측 정확도를 위하여 이에 대한 보정이 수행되어야 한다. 본 연구의 이론은 반도체 생산공정의 액상전구체 정밀공급제어기 최적설계에 적용될 수 있다. The theory on the cooling type liquid mass flow meter using a thermoelectric cooler (TEC) was deduced from the simple theory of tube flow convective heat transfer under a constant wall temperature condition. The effects of design parameters such as the distance between up and downstream thermistors, tube outer diameter, contact thermal resistance between the TEC and the tube outer surface, and surrounding temperature were evaluated via numerical calculations, and consequently, a mathematical model in the form of an exponential function was established. Based on this model, a limit in the resolution of the minimum and maximum flow rate measurements was confirmed, and design guidelines for extending these limits were presented. Designs to widen the range of mass flow rates in maximum and minimum tend to be opposite to each other. The theory of this study is important in the optimal design of the liquid precursor supplying system in the semiconductor production process.
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