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Mixing in a Microchannel by using Induced-charge Electro-osmosis
전영훈(Young Hun Jeon),허영근(Young Gun Heo),정원혁(Won Hyuk Jung),수레수 알라파티(Suresh Alapati),서용권(Yong Kweon Suh) 한국가시화정보학회 2010 한국가시화정보학회지 Vol.8 No.4
This paper presents an experimental study on the performance of a micro-mixer using AC electro-osmotic flow. The microchannel is made of PDMS for the side and top walls and glass patterned with ITO for the bottom wall. We first investigated the effect of the applied potential as well as the frequency on the slip velocity. We have found that the slip velocity is roughly proportional to the applied voltage in line with the Helmholtz-Smoluchowski equation and there is an optimum frequency at which the slip velocity becomes maximized. To find the optimum parameters for mixing device we tested our device for various design parameters. It turned out that the best mixing effect is obtained approximately when the electrode angle is 30°, electrode width 200 ㎛, and the frequency of power supply 700 ㎐.
모듈러 건축 현장의 위험성평가를 위한 양중작업 위험요소 분석
전영훈 ( Jun Young-hun ),김균태 ( Kim Kyoon-tai ),전은비 ( Jeon Eun-bi ) 한국건축시공학회 2021 한국건축시공학회 학술발표대회 논문집 Vol.21 No.1
In modular construction, it is insufficient for safety management of workers, and workers are still exposed to the risk of accidents due to work at high places for lifting and assembly work in modular construction sites. Therefore, it is necessary when preventive safety management through risk management of workers on modular construction sites. ?This study is a basic study for the risk assessment(checklist) of modular construction, and the purpose of this study is to analyze the risk factors of the module lifting work at the modular construction site. It is intended to identify the hazard risk factors and improvement measures of the existing lifting operation, by analyzing the case of the risk assessment of the existing RC method, and to identify the risk factors for each work process when lifting the module. In the future, the results of this study are expected to be utilized in the development of checklists for risk assessment as safety management plan for modular construction sites.
사례분석을 통한 모듈러 건축의 현장 안전관리 분류체계(안) 도출
전영훈 ( Jun Young-hun ),김균태 ( Kim Kyoon-tai ),전은비 ( Jeon Eun-bi ) 한국건축시공학회 2020 한국건축시공학회 학술발표대회 논문집 Vol.20 No.2
In modular construction, safety management is required to prevent the occurrence of risk factors such as lifting work and high place work due to the characteristics of the construction method. Therefore, this study is a basic study for safety management of modular construction, and the purpose of this study is to compare and analyze the classification system of modular construction derived by analyzing the construction process of the existing case. Based on the results of this study, the safety management classification system will be used in future research to derive safety management factors in modular construction.
외부 가스 유동에 의한 미소 액적 내부 유동 제어 및 가시화
허영근(Young Gun Heo),허효원(Hyo Weon Heo),전영훈(Young Hun Jeon),서용권(Yong Kweon Suh) 한국가시화정보학회 2010 한국가시화정보학회 학술발표대회 논문집 Vol.2010 No.11
We conducted experimental visualization and numerical simulations of flow inside a droplet subjected to an external gas flow. The purpose of this study is to confirm a flow-control method provided by agas flow over a droplet, which may be used in the enhancement of the semiconductor performance, in the case where the semiconductors are manufactured by the principle of inkjet printing. Our ultimate target is to remove the coffee-stain effect and make the osc align in the direction of current in between a pair of micro electrodes.
허영근(Young Gun Heo),전영훈(Young-Hun Jeon),서용권(Yong Kweon Suh) 한국가시화정보학회 2010 한국가시화정보학회지 Vol.7 No.2
In this paper we report the method of visualizing and measuring the fluid flow within a small droplet of millimeter size. We use a vertical laser sheet in visualization of the micrometer size and special attention is given to the arrangement of microscope to obtain clear images. Then we use a PIV technique to measure the velocity of the internal flow from the images taken. Since the droplet is of spherical shape, the images represent highly deteriorated picture of the real objects due to the refraction phenomenon. In order to compensate the refraction, we in this study developed two kinds of methods for the real velocity. In the first method, the refracted images are directly used to obtain the velocity in the image space, and then the velocity is transformed to the real space. In the second method the images are first transformed to the real-space objects, and then the PIV is used to measure the velocity field. We compared the two results to prove the usefulness of the compensation technique.
CFX 코드를 사용한 비정상 DC 전기삼투 유동 해석기법 개발
허영근(Young Gun Heo),전영훈(Young Hun Jeon),정종현(Jong Hyeon Jeong),서용권(Yong Kweon Suh) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11
In this study, we couple a commercial code, ANSYS CFX and Fortran codes for solving electro-osmotic flows around a pair of electrodes receiving DC potentials attached to the top and bottom walls of a rectangular domain. Up to now, no work has been presented in the literature which obtained the solutions of the electro-osmotic-flow problems by using the CFX. Difficulties in this techniques are: Firstly, the ion transport equations (i.e., Nernst-Planck equations) must be solved by using the general transport equation provided by CFX, but in most often there is numerical instability in treating the source terms. Secondly, to calculate the source term we need to evaluate the electric field which must be obtained from a separate Fortran code in terms of the potential which is given from the solution of the Poisson equation. In this case, care must be given to the computer-memory problem. In this study, we develop a module of Fortran programs which are used in solving the ion transport problem in coupling with the CFX. We will present how the developed code is applied to solving the dc electro-osmotic problem within a simple geometry. We also address various problems encountered during the development process and explain how such problems are tackled.
임상연구 : 복식 전자궁 적출술 후 정맥 내 자가통증조절장치에 혼합된 Midazolam의 항구토효과
정석호 ( Seok Ho Jung ),전영훈 ( Young Hun Jeon ) 대한마취과학회 2006 Korean Journal of Anesthesiology Vol.51 No.5
Background: Midazolam has been reported to decrease postoperative nausea and vomiting (PONV). We studied the antiemetic effect of midazolam in patients receiving intravenous patient-controlled analgesia (PCA) using morphine after total abdominal hysterectomy. Methods: Group C (n = 27) received bolus of morphine 5 mg and PCA of morphine 1 mg/ml. Group M1 (n = 27) received bolus of morphine 5 mg and midazolam 1 mg and PCA of midazolam 0.2 mg/ml mixed with morphine 1 mg/ml. Group M2 (n = 27) received bolus of morphine 5 mg and midazolam 1 mg and PCA of midazolam 0.4 mg/ml mixed with morphine 1 mg/ml. The PCA delivery system was programmed to deliver 1 ml of the test solution per demand with a 10 min lockout interval and no background infusion. The incidence of PONV, metoclopramide and ketorolac usage, morphine and midazolam consumption, pain, sedation, and other side effects were assessed at 1, 4, 8, 16, 24, 36 and 48 h after the operation. Results: The incidences of PONV were 19 (70%) in Group C, 14 (52%) in Group M1 and 10 (37%) in Group M2. The incidence of PONV in Group M2 was significantly lower than that in Group C (P < 0.05). Patients in Group M2 experienced more sedation than those in Group C (P < 0.05). No severe sedation was observed in all groups. Conclusions: Combination of midazolam 0.4 mg per morphine 1 mg in PCA had more effective antiemetic efficacy than control without significant adverse effects. (Korean J Anesthesiol 2006; 51: 591~7)