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Local Well-Posedness and Blow-Up for the Solutions to the Axisymmetric Inviscid Hall-MHD Equations
Jeong, Eunji,Kim, Junha,Lee, Jihoon Hindawi Limited 2018 Advances in mathematical physics Vol.2018 No.-
<P>In this paper, we consider the regularity problem of the solutions to the axisymmetric, inviscid, and incompressible Hall-magnetohydrodynamics (Hall-MHD) equations. First, we obtain the local-in-time existence of sufficiently regular solutions to the axisymmetric inviscid Hall-MHD equations without resistivity. Second, we consider the inviscid axisymmetric Hall equations without fluids and prove that there exists a finite time blow-up of a classical solution due to the Hall term. Finally, we obtain some blow-up criteria for the axisymmetric resistive and inviscid Hall-MHD equations.</P>
전준하(Junha Jeon),강기준(Ki-Jun Kang),권현진(Hyun-Jin Kwon),장세명(Se-Myong Chang),정재복(Jae-Bok Jeong),백재구(Jae-Gu Baek) 한국항공우주학회 2018 韓國航空宇宙學會誌 Vol.46 No.9
본 연구에서는 쿼드콥터형 소형 무인 드론에 이산화탄소를 작동 기체로 하는 가스총을 설치하여 가축 방역에 응용할 수 있는 발사체 및 결합 유닛을 개발하였다. 시스템은 상용드론과 가스총, 솔레노이드 밸브, 무선 통신 제어기 등으로 구성된다. 발사된 탄환의 속도를 측정하고, 지상 시험, 실제 비행체에의 탑재 시험 등을 거쳐 최종 검증하였다. 본 연구개발을 통하여 농업, 소방 등의 다양한 방역 및 방재 분야에 발사체 기술을 적용할 수 있는 가능성을 확인하였다. In this investigation, a gas gun is proposed driven by carbon dioxide gas and installed on a quadcopter-type small unmanned drone for the purpose of cattle vaccination, and we developed a launcher and its connection unit. The system consists of a commercial drone, a gas gun, a solenoid valve, and the remote communication controller, etc. The velocity of launched projectile is measured, and the full system is finally validated through ground test and flight examination loaded for the real aircraft. The feasibility is checked if this technology is applicable to various disease abatement and hazard mitigation in the fields of agriculture and fire-fighting with the present research and development.
Substance P improves MSC-mediated RPE regeneration by modulating PDGF-BB
Jung, Jihyun,Jeong, Junha,Hong, Hyun Sook Elsevier 2019 Biochemical and biophysical research communication Vol.515 No.4
<P><B>Abstract</B></P> <P>Stem cells have regenerative potentials that can be used for the treatment of critical and incurable diseases. Age-related macular degeneration (ARMD) and diabetic retinopathy are one of the most severe retinal disorders, which are mostly attributed to impairment of retinal pigmented epithelium (RPE). Thus, restoration of RPE is the main therapeutic approach to prevent the development of ocular diseases, such as ARMD. In this study, we have investigated the role of substance P (SP) on bone marrow mesenchymal stem cell (MSC)-mediated RPE regeneration in vitro. The MSCs were primed with SP followed by the addition of conditioned medium (MSC<SUP>SP−CM</SUP>) to RPE. The effects of MSC<SUP>SP−CM</SUP> on RPE activity was evaluated by assessing viability, proliferation rate, and migration of RPE. Ex vivo long-term culture led to altered cellular characteristics of MSCs by weakening cell viability, cytokine secretion, and differentiation potential. The conditioned medium of early passage MSC (E-MSC<SUP>CM</SUP>) enhanced the RPE viability and migration, whereas the late passage MSC (L-MSC<SUP>CM</SUP>) hardly influenced the RPE activity. SP priming, however, facilitated the inductive effects of MSC, and SP effect was more distinct in the late passage than in the early passage. Moreover, it was revealed that SP could exert its effects by modulating PDGF-BB secretion in the MSCs.</P> <P>Taken together, these results suggested that SP could restore the therapeutic effects of MSCs on retinal diseases by elevating their proliferative and paracrine activities through PDGF-PDGFR signaling in ex vivo culture.</P> <P><B>Highlights</B></P> <P> <UL> <LI> BMSC enhances RPE activity by paracrine factors. </LI> <LI> Paracrine potential of BMSC decreases as passage number increases. </LI> <LI> SP elevates cytokine secretion in BMSC. </LI> <LI> SP enhances MSC-mediated RPE regeneration. </LI> </UL> </P>
Model schematics of carbon-nanotube-based-nanomechanical-tuner using piezoelectric strain
Won Kang, Jeong,Kim, Ki-Sub,Ryang Byun, Ki,Kang, Eu-Seok,Lee, Junha,Kuen Kwon, Oh,Gyu Choi, Young,Hwang, Ho Jung Elsevier 2010 Physica E, Low-dimensional systems & nanostructure Vol.42 No.7
<P><B>Abstract</B></P><P>Model schematics of a carbon-nanotube-based frequency tuner are presented and their vibration frequencies are analyzed by theoretical approaches such as classical molecular dynamics simulations and the continuum model equation. Outertube’s position displacement by a piezoelectric strain of a piezoelectric material induces the change of the vibrating carbon nanotube length. The desired frequencies are achieved by manipulating the electric potential applied to the piezoelectric material.</P>
Kim, Jee Yeon,Hwang, Junha,Lee, Seo Hyun,Lee, Hyo Jin,Jelinek, Jaroslav,Jeong, Hyeseon,Lim, Jae Sung,Kim, Jin Man,Song, Kyu Sang,Kim, Byung Hoon,Lee, Sukhoon,Kim, Jei BioMed Central 2015 Clinical epigenetics Vol.7 No.-
<P><B>Background</B></P><P>The vascular endothelial growth factor (VEGF)-VEGF receptor (VEGFR) signaling pathway is involved in cancer-related biological functions and is a therapeutic target in cancer. However, the influence of epigenetic regulation of VEGF-VEGFR signaling-related genes remains unclear. Here, we evaluated the effects of <I>FLT1</I> and <I>KDR</I> promoter hypermethylation combined with drugs targeting VEGF-VEGFR signaling on cancer-related phenotypes in renal cancer cells (RCCs) and examined changes in <I>FLT1</I> and <I>KDR</I> promoter hypermethylation in tissues from patients with renal cancer.</P><P><B>Results</B></P><P>In vitro experiments were performed to evaluate the effects of beavacizumab (an anti-VEGF antibody), an anti-FLT1 peptide, an anti-KDR antibody, and the VEGFR tyrosine kinase inhibitors (TKIs) sunitinib and axitinib in 13 RCC lines with different levels of <I>FLT1</I> and/or <I>KDR</I> promoter methylation and in 2 FLT1 or KDR in vitro knockdown models. The synergistic effects of sunitinib and axitinib treatment were also evaluated in four RCC lines having different levels of <I>FLT1</I> and/or <I>KDR</I> methylation. In our in vitro experiments, bevacizumab and an anti-KDR antibody did not affect the proliferation of RCCs having <I>FLT1</I> and/or <I>KDR</I> hypermethylation. In contrast, in RCCs with <I>FLT1</I> hypermethylation, proliferation inhibition was counteracted by treatment with an anti-FLT1 peptide and both VEGF-TKIs (sunitinib and axitinib). Demethylation with sunitinib or axitinib synergistically increased proliferation inhibition in the RCCs exhibiting <I>FLT1</I> hypermethylation. Using in vitro <I>FLT1</I> or <I>KDR</I> knockdown models, decreased proliferation inhibition following anti-FLT1 peptide, sunitinib, and axitinib treatment was observed only in <I>FLT1</I>-knockdown cells. In patients with renal cancer who received sunitinib, <I>FLT1</I> promoter methylation was higher in renal cancer tissues from eight nonresponders (stable or progressive disease assessed by the Response Evaluation Criteria in Solid Tumors) than in cancer tissues from five responders (complete response or partial response).</P><P><B>Conclusions</B></P><P>The present data showed that hypermethylated <I>FLT1</I> was important for the efficacy of anti-VEGF/VEGFR drugs targeting FLT1 or intracellular VEGFR signaling. <I>FLT1</I> hypermethylation causing alterations of FLT1 function could serve as a useful biomarker for predicting changes in <I>FLT1</I> status in RCCs.</P><P><B>Electronic supplementary material</B></P><P>The online version of this article (doi:10.1186/s13148-015-0134-9) contains supplementary material, which is available to authorized users.</P>
박치성(Chi Seong Park),조준하(Junha Jo),심정섭(Jeong Seop Sim),김동규(Dong Kyue Kim) 한국정보과학회 2006 한국정보과학회 학술발표논문집 Vol.33 No.1
써픽스 배열은 사전적 순서로 정렬된 써픽스들의 인덱스를 저장한 인덱스 자료구조로서, 긴 텍스트에서 반복되는 패턴 검색 시 효율적으로 사용될 수 있다. 하지만 O(n log ∑ ) 비트의 텍스트보다 큰 O(nlog n) 비트 공간을 차지하기 때문에 대용량의 텍스트에 대해서는 큰 공간을 필요로 하는 문제점이 있다. 이를 해결하기 위해 압축된 써픽스 배열이 제안되었지만, 구축 시 이미 만들어진 써픽스 배열을 이용하기 때문에 실제 사용 공간을 줄이지는 못했다. 최근 써픽스 배열 없이 텍스트에서 직접 압축된 써픽스 배열을 구축할 수 있는 두 가지 알고리즘이 개발되었다. 본 논문에서는 이 두 가지 알고리즘을 구현한 후, 구축 시간과 사용 공간 등의 실험을 통해 기존의 써픽스 배열들과의 성능을 비교하고 분석한다.