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A case of foreign body granuloma from its own hair as a foreign body
( Jaewon Lee ),( Eunjin Doh ),( Hyun Sun Yoon ),( Soyun Cho ),( Hyun Sun Park ) 대한피부과학회 2016 대한피부과학회 학술발표대회집 Vol.68 No.1
Hair is usually growing outward to the hair follicle. However, it is known that the hairs sometimes grows inwardly and causes some problems such as inflammatory skin diseases. A 21-year-old Korean female presented with a painful lump on her left axilla arising a month ago. She denied any trauma on the area and also denied any history of receiving invasive procedures or implantation of prosthetic materials. Ultrasonographic study of the lesion was done and we found a linear curly hyperechogenic material inside the mass. Then punch biopsy was done and we found the axillary hair inside the lesion during the biopsy procedure. Histopathologic finding showed a feature of foreign body granuloma. Therefore, the patient was diagnosed with foreign body granuloma formed by her own hair. There are previous case reports about ingrowing hair, so-called cutaneous pili migrans or creeping hair. But there are few cases about ones`` own hair acting as a foreign body. Herein we report a case of foreign body granuloma from her own axillary hair for its rarity and educational values.
Analysis and Experimental Evaluation of Normal Force of Linear Induction Motor for Maglev Vehicle
Lim, Jaewon,Jeong, Jae-Hoon,Kim, Chang-Hyun,Ha, Chang-Wan,Park, Doh-Young IEEE 2017 IEEE transactions on magnetics Vol.53 No.11
<P>This paper presents the analysis and experimental of the effective normal force and power consumption in a maglev vehicle. A maglev vehicle employs the electromagnets as suspension and linear motors for propulsion. These components give the higher ride comfort but suffered from energy efficiency. Therefore, a vector control-based algorithm and various air gaps are employed to increase the propulsion efficiency and lower the system energy consumption. The effective levitation load according to the levitation gap and normal force of a linear induction motor is calculated by power consumption in a levitation system and compared with finite-element analysis results. The experiment is carried out with the full-scaled train in test line and the efficiency of a propulsion system is also presented.</P>
임재원(Jaewon Lim),정재훈(Jaehoon Jung),박도영(Doh-young Park) 한국철도학회 2014 한국철도학회 학술발표대회논문집 Vol.2014 No.10
자기부상열차는 뛰어난 승차감과 비 접촉 추진 방식에 따른 분진발생의 저감, 저소음의 특징 등에 차세대 교통수단으로 많은 관심을 받아왔다. 특히 도시형 자기부상열차의 실용화에 이어 초고속, 중고속 영역의 자기부상연구도 활발하게 진행되고 있다. 중고속 자기부상열차를 구현하는데 있어서 도시형 자기부상열차와 차별화 되는 점은 도시형자기부상열차에서 수동적으로 제어되었던 측 방향 변위 제어 시스템이라 할 수 있다. 열차가 고속화 될수록 곡선구간 주행 및 측면 외란에 의해 측방향 변위가 더 많이 발생하게 되고 이는 부상력 저하와 같은 외란으로 작용하여 부상안정성에도 직접적으로 영향을 미치게 된다. 본 논문에서는 중고속 자기부상열차용 안내 시스템을 제안하며 안내 시스템과 부상 시스템을 동시에 적용, 해석하여 자기적인 상호 작용을 검토하고 부상 시스템과 결합한 안내 제어 가능성을 검토하고자 한다. Maglev vehicle has received lots of attention as next generation transportation due to superb driving comfort and non-contact characteristic. Researches on super high and medium high speed maglev train have been carried out after commercialization project of urban maglev transit. The major distinction of urban maglev transit and medium speed maglev is the passive lateral guidance system. The higher speed train receives the more side disturbance and displacement. This paper deals the lateral guidance system of medium high speed maglev vehicle. The interactions of levitation and guidance system with guidance control feasibility are also presented.
Lim, Jaewon,Park, Doh-Young,Jeong, Jae-Hoon IEEE 2018 IEEE transactions on magnetics Vol.54 No.11
<P>This paper presents the electromagnetic characteristics of a linear induction motor (LIM) for a semi-high-speed magnetic levitation or maglev vehicle. The propulsion system of the maglev train provides excellent ride quality, but still has a disadvantage in that the propulsion efficiency is low owing to its inherent characteristics. In particular, in the propulsion system of maglev trains with a relatively large air gap, the increase in the propulsion efficiency remains an important issue. The propulsion system generates a vertical force during propulsion control. To ensure the stability of the propulsion system, the electromagnetic characteristics of the propulsion system’s vertical force need to be interpreted accurately. The normal force and thrust are analyzed with the finite-element method considering the varying speed and slip. To improve the propulsion efficiency, variable slip-frequency operation is proposed without deteriorating the levitation performance. The thrust map of the LIM with allowable slip frequency is also presented.</P>
Jeong, Jaewon,Kim, Soojin,Lim, Da-Sol,Kim, Seo-Hea,Doh, Heeju,Kim, So-Dam,Song, Yun Seon The Korean Society for Brain and Neural Science 2017 Experimental Neurobiology Vol.26 No.4
<P>Postconditioning has been shown to protect the mouse brain from ischemic injury. However, the neuroprotective mechanisms of postconditioning remain elusive. We have found that toll-like receptor 5 (TLR5) plays an integral role in postconditioning-induced neuroprotection through Akt/nuclear factor kappa B (NF-κB) activation in cerebral ischemia. Compared to animals that received 30 min of transient middle cerebral artery occlusion (tMCAO) group, animals that also underwent postconditioning showed a significant reduction of up to 60.51% in infarct volume. Postconditioning increased phospho-Akt (p-Akt) levels and NF-κB translocation to the nucleus as early as 1 h after tMCAO and oxygen-glucose deprivation. Furthermore, inhibition of Akt by Akt inhibitor IV decreased NF-κB promoter activity after postconditioning. Immunoprecipitation showed that interactions between TLR5, MyD88, and p-Akt were increased from postconditioning both <I>in vivo</I> and <I>in vitro</I>. Similar to postconditioning, flagellin, an agonist of TLR5, increased NF-κB nuclear translocation and Akt phosphorylation. Our results suggest that postconditioning has neuroprotective effects by activating NF-κB and Akt survival pathways via TLR5 after cerebral ischemia. Additionally, the TLR5 agonist flagellin can simulate the neuroprotective mechanism of postconditioning in cerebral ischemia.</P>
자기부상용 공극 센서의 필터 설계에 따른 부상 안정성 비교
김민(Min Kim),임재원(Jaewon Lim),김창현(Chang-Hyun Kim),하창완(Chang-Wan Ha),원문철(Mooncheol Won),박도영(Doh Young Park) 한국철도학회 2015 한국철도학회 학술발표대회논문집 Vol.2015 No.10
자기부상 열차와 같이 일정 곡극을 기준으로 부상을 유지하는 시스템의 경우, 부상 안정성 구현을 위해서는 부상 공극을 측정하는 센서의 정확성이 필수적으로 확보되어야한다. 하지만 시스템의 구성에 있어서 전자석 구동에 필요한 전원 및 전류 제어기에 의해 센서에 고주파 노이즈가 발생하게 되며, 이는 직접적으로 부상 제어에 악영향을 준다. 본 논문에서는 부상 정밀도 향상을 위해 네 가지 디지털 필터를 이용한 센서 신호의 노이즈 저감 효과를 확인한다. 또한, MATLAB/Simulink 해석 모델 개발 및 시뮬레이션을 통해 부상에 미치는 영향을 분석하고자 한다. Magnetic levitation system travels with a constant gap. High resolution and low noise sensor system is key factor for stable levitation control. However, power source and current controller have noise component that cause the vibration and levitation failure. In this paper, four digital filters are applied for gap sensor noise reduction. Levitation simulation results with each filter are compared to evaluate the noise reduction performance. MATLAB/Simulink software is used to analyze the levitation stability and system modeling.
Flash D 탈자방법에서 수직자화예측을 위한 초기자화율에 관한 검토
김영학,도재원,Kim, Young-Hak,Doh, Jaewon 한국군사과학기술학회 2014 한국군사과학기술학회지 Vol.17 No.5
A permanent vertical magnetization should be obtained to counteract induced vertical magnetization due to the earth's background field during the Flash D demagnetization process. A vertical susceptibility is needed to calculate a extra-permanent magnetization, which is needed to control the permanent vertical magnetization in stage 2 of Flash D demagnetization and added to the final vertical permanent magnetization. Two susceptibilities were found in this paper. One is obtained from the extra-magnetization. The other is obtained by magnetic field measurement from the scaled physical vessel when the vessel is excited by vertical magnetic field. The initial susceptibility by the extra-magnetization was 0.101~0.109 and the one from the measured magnetic field was 0.122. Two susceptibilities have a good agreement each other. From this paper, it is found that the susceptibility is able to appllied to calculate the extr-magnetization.
Sang Uk Park,Chan Yong Zun,Doh-Young Park,Jaewon Lim,Hyung Soo Mok 한국철도학회 2016 International Journal of Railway Vol.9 No.2
In this paper, a study on the efficiency improvement of the magnetic levitation train using the LIM (Linear Induction Motor) was presented. The maglev train has the advantage of being environmentally friendly since much less noise and dust is produced. However, due to structural limitation, compared to a rotating induction motor, linear induction motor, the main propulsion engine of the maglev train has a relatively greater air gap and hence has the lower operation efficiency. In this paper, the relationship between the operating condition of the train and the slip frequency has been investigated to find out the optimum slip frequency that might improve the efficiency of the magnetic levitation train with linear induction motor. The slip frequency is variable during the operation by this relationship only within a range that does not affect the levitation system of the train. After that, the comparison of the efficiency between the conventional control method with the slip frequency fixed at 13.5[Hz] and the proposed method with the slip frequency variable from 9.5[Hz] to 6.5[Hz] has been conducted by simulation using Simplorer. Experiments of 19.5[ton] magnetic levitation trains owned by Korea Institute of Machinery and Materials were carried out to verify the simulation results.