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See How I Eat My Greens—Autophagy in Plant Cells
정태준 한국식물학회 2011 Journal of Plant Biology Vol.54 No.6
Eukaryotic cells have two conserved pathways for degrading polypeptides. One is the highly selective ubiquitin–proteasome system, and the other is autophagy,a bulk degradation pathway to a lytic compartment. Autophagy in plant cells has important roles in development and responses to abiotic and biotic stresses. Furthermore, plant autophagy has been implicated in vacuole biogenesis and Golgi-independent targeting of cytoplasmic materials to vacuoles. Here I present four questions that are frequently asked by plant scientists interested in autophagy. The first question relating to tools for plant autophagy research is relatively easy to answer, while the others are open questions about regulation of autophagy, autophagic cargoes, and potential differences of plant autophagic routes from corresponding metazoan pathways. This review will discuss recent progress that may provide the answers for the latter questions.
정태준 한양대학교 의과대학 1997 한양의대 학술지 Vol.17 No.2
AIDS is a global epidemic with virtually every country in t4he world reporting cases. In addition to the United States, areas of the world with the highest incidence include western Europe, central Africa, South America, and Asia. The clinical consequences of HIV infection form a spectrum ranging from the asymptomatic state to severe disease. The majority of individuals experience no recognizable symptoms or signs at the time of initial infection, but some patients develop an acute illness approximately 3 to 6 weeks following primary infection. It is characterized by nonspecific signs and symptoms including fevers, rigors, arthralgias, maculopapular rash, diarrhea, and aseptic meningitis. The syndrome lasts 2 to 3 weeks and resolves spontaneously. Seroconversion usually occurs 8 to 12 weeks after presumed exposure. The most common clinical manifestation of AIDS is opportunistic infection. It is not unusual for an AIDS patient to have more than one opportunistic infection simultaneously. Pneumocystis carinii pneumonia is the most common opportunistic infection, occurring in approximately 80% of patients at some point during the course of their illness. However, neurologic diseases, Koposi's sarcoma, certain lymphoid neoplasms, and second malignancis impose another clinical obstacles to overcome. The development of a vaccine to prevent infection and disease with HIV will be an important tool in the strategy for world-wide containment of the AIDS epidemic. Several candidate vaccines are undergoing clinical trials in humans. These studies lend optimism to the feasibility of developing a safe and effective vaccine for HIV in the future.
정태준,신영기,Jung, Tae Joon,Shin, Younggy 한국플랜트학회 2021 플랜트 저널 Vol.17 No.3
드릴 스트링의 진동 문제는 수년간 드릴링 성능 저하의 주요 원인 중 하나로 인식되어 왔으며, 굴착 작업 시 발생하는 과도한 진동은 드릴링의 효율성, 파이프 피로, 비트의 수명 단축으로 인하여 고장을 초래할 수 있다. 이러한 진동의 원인은 드릴 스트링이 굴착 작업 중 궤적에 따라 파이프의 굽힘과 wellbore와의 접촉으로 인해 마찰이 발생하고 이러한 진동은 일반적으로 축 방향, 굴곡 및 비틀림 변형을 일으킨다. 본 연구에서는 Khulief와 Al-Naser가 제시한 모델을 바탕으로 드릴 스트링에 6자유도(DOF)의 구성요소를 갖는 모델을 적용하여 curved beam의 수치해석 값과 Analytical값을 비교하여 검증하고 드릴 스트링에 hookload와 WOB 경계조건을 주어 각 element 마다 동적 거동을 분석하였다. 실제 궤적을 적용하여 드릴 파이프의 굽힘이나 중력으로 인하여 Wellbore와 접촉되는 부분에 마찰을 적용하였고, 또한 마찰 작용 시 일정한 축 방향 속도를 유지하기 위한 PI제어 값을 설계하여 drillstring 전체의 각속도 변화와 실제 드릴 굴착 작업 중 발생하는 stick slip현상을 관찰하였다. The equation of motion of the drill string along the excavation trajectory was analyzed using the Lagrangian approach together with the finite element method (FEM). A drill string of circular cross section is constructed by combining a plurality of circular axes each having 12 degrees of freedom (DOF). FEM analysis can observe the vibration and dynamic changes of the entire drill string, and it is easy to apply comprehensive boundary conditions to reproduce the simulation of a realistic drill string. In this study, the constructed FEM motel was simulated. In order to apply the FEM program to the actual drill trajectory, the dynamic analysis of the curved beam was verified by comparison with the actual values. The dynamic change over time was observed.