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Turbulent Transition Control Using Porous Surfaces in Hypersonic Boundary Layer
임지섭,김민우,배하준,Ray-Sing Lin,지솔근 한국항공우주학회 2023 International Journal of Aeronautical and Space Sc Vol.24 No.4
Hypersonic boundary layer on porous surfaces is simulated to investigate the effect of porous surfaces on the transition process. The fundamental breakdown involving the Mack second mode is computed using the direct numerical simulation (DNS) solver of Lim et al. (Comput Fluids 240:105437, 2022). Because it is computationally challenge to resolve numerous pores, the impedance boundary condition of a porous surface is pursued in this study to model the absorptive characteristics of a porous surface. The impedance boundary condition for a porous surface is implemented in the DNS solver and validated against relevant literature data. The stabilization of the Mack second mode on porous surfaces is well resolved in the current computations. Based on the validated numerical setup, 3D DNS computations of the hypersonic boundary layer over a porous surface are conducted. The current porous surface is optimized to absorb the Mack second mode. In this study, it is clearly shown that the turbulent transition involving the Mack second mode can be effectively delayed on the porous surface.
전개가능형 가위구조시스템을 이용한 쉘터구조물에의 적용성 검토에 관한 실험적 연구
임지섭,최상순,정을석,김승덕,Lim, Ji-Sub,Choi, Sang-Soon,Jeong, Eul-Seok,Kim, Seung-Deog 한국공간구조학회 2014 한국공간구조학회지 Vol.14 No.3
Recently, natural disasters such as earthquake, tsunami, typhoon and tornado are increasing, and cause huge economical loses and victim. Thus, when the disaster occurs, it is important to prepare emergency evacuation shelters for fast and easy construction compared to general building system. And, deployable structures will provide a great help for such aim. Deployable structures have the great advantage of being faster and easier to erect and dismantle compared to conventional building forms. In this study, we confirm the possibility of deployment for shelter structures using scissor structure system. First, Basic model was performed to recognize the appllicability of the deployable systems of the dome-shaped structure. Second, Advanced model that more improved inner space and deployment mechanism was confirmed.
안정성 해석 결합 기법을 활용한 고속 경계층 난류 천이 수치해석 연구
임지섭(Jiseop Lim),김민우(Minwoo Kim),지솔근(Solkeun Jee) 대한기계학회 2023 대한기계학회 춘추학술대회 Vol.2023 No.11
Since the aerodynamic properties significantly change before and after laminar-to-turbulent transition, the capability of transition prediction is essential in designing high-speed aircraft. In this study, an efficient high-fidelity approach is investigated for turbulent transition in high-speed boundary layer flows. The proposed method is to combine stability analysis with an eddy-resolving simulation, such as large-eddy simulation and direct numerical simulation. The stability analysis is utilized to efficiently obtain instability modes that can trigger boundary layer transition. The subsequently transitional flow is then accurately simulated using eddy-resolving simulations. It is previously shown that the combined approach is capable of accurately resolving turbulent transition of subsonic boundary layer. In this study, a framework of the combined approach has been demonstrated in supersonic (Mach 3) and hypersonic (Mach 6) boundary layer flows.
ME 바이오센서를 이용한 Escherichia coli K-12의 검출
임지섭 ( Ji Seob Lim ),민현정 ( Hyun Jung Min ),( B. A. Chin ),조병관 ( Byoung-kwan Cho ) 한국농업기계학회 2017 한국농업기계학회 학술발표논문집 Vol.22 No.2
식품 유해 미생물로 인한 식중독 사고 중 병원성 대장균에 의한 식중독사고가 가장 빈번하다. 이는 부패된 고기류, 유제품 등을 부주위하게 다루거나 취식하므로 발생하게 된다. 최근 소비자들의 식품 및 농산물 안전성에 대한 관심이 높아지고 있어 농식품에 대한 신속하고 정확한 병원균 검출이 중요해지고 있다. 본 연구에서는 Metglas라고 불리는 자기 탄성체 리본 소재에 공진이 발생하도록 자기장을 걸어 자기변형현상을 유도하므로 식중독의 원인이 되는 E-Coli K-12를 측정할 수 있는 바이오센서를 개발하고자 하였다. 실험에 사용된 Metglas는 Metglas 2605 SA1 (Thickness=23μm, Metglas Co, USA) 이며 스퍼터를 이용하여 표면에 Ti와 Au를 10 nm와 100 nm 두께로 순차적으로 증착한 뒤에 250°C에서 어닐링 하여 Magnetoelastic (ME) 센서를 만들었다. 센서에서 나오는 신호는 네트워크 분석기(Network Analyzer 5061B, KEYSIGHT Co, Korea)를 사용하여 측정하였다. 사용된 E-Coli K-12 항체는 polyclonal antibody solution(20B04308, Agilent 33220A, Meridian Life Science)이며, PEI (Polyethyleneimine solution P3143 Sigma-Aldrich Co, USA)와 Streptavidin(S4762 Sigma-Aldrich Co, USA)는 항체를 ME센서에 고정하기 위해서 사용하였다. 식중독을 유발하는 Escherichia coli (E.coli) K-12가 센서에 부착되었을 때 2.34 MHz 주파수에서 약 0.4 MHz 정도의 위상차를 보였다. ME 바이오센서 기술은 식중독균인 Escherichia coli (E.coli) K-12검출에 가능성을 보였다.
임지섭(Ji-Seop Lim),김현정(Hyun-Jung Kim),김임규(Im-Kyu Kim),강은찬(Eun-Chan Kang),이상민(Sang-Min Lee),공보금(Bo-Geum Kong),강제욱(Je-Wook Kang),문정준(Jung-Joon Moon),전동욱(Dong-Wook Jeon),정도운(Do-Un Jung) 대한노인정신의학회 2014 노인정신의학 Vol.18 No.2
Objective:This study was performed to analyze the clinical variables associated with occurrence of delirium tremens (DT) in inpatients with alcohol dependence initially admitted with diseases unrelated to alcohol. Methods:This study included 132 inpatients seeking treatment for medical problem with acute alcohol withdrawal. The cases were divided into two groups : with DT group (n=44), without DT group (n=88). We compared the epidemiologic data, alcohol withdrawal symptoms and serum analysis data between two groups. We used the logistic regression to predict risk factors for DT. Results:The DT group had more severe alcohol withdrawal symptoms, more amount of drinking alcohol, more number of drinking per month, higher blood urea nitrogen (BUN), creatinine, amylase, C-reactive protein and lower serum total protein than the without-DT group. According to the result of a logistic regression, occurrence of DT showed correlation with the following factors : sweating, hallucination, agitation, amount of alcohol consumption, number of drinking per month. Conclusion:Our study suggests development of DT was correlated with severe alcohol withdrawal symptoms, high BUN, creatinine and low total serum protein. Therefore, during assessment of alcohol dependent patients, clinicians should keep these parameters in mind in order to prevent DT.