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황재혁,조현권,이혜진,박영창,박진호 한국 항공대학교 항공산업기술연구소 2001 航空宇宙産業技術硏究所 硏究誌 Vol.11 No.-
본 논문에서는 유연한 부착물을 갖는 우주구조물의 회전 시 발생할 수 있는 잔류진동을 최소화하고 또한 그 응용 범위가 넓은 입력설계 방법과 등가화 된 시간 지연기법을 다루었다. 먼저 Singh과 Vadali가 제안한 제어기를 이용하여 하나의 모드에 대한 시간 지연 제어기를 설계하고 입력설계 방법과 등가화 됨을 보였다. 그리고 실제 모델에 대한 적용과 해석을 위하여 우주구조물에서 많이 사용되는 유연구조물의 운동방정식을 유도하고 해석하였고, 실험을 통하여 입력 설계 방법과 시간 지연 기법을 이용한 잔류 진동 제어에 대한 성능이 우수함을 확인할 수 있었다. In this paper, the time-delay control (TDC) design methods for command signals to minimize the induced residual vibration followed by the maneuvers of the flexible structures has been studied. The equivalence between the time-delay control and the input shaping control has been shown and TDC is applied to control the residual vibration of the flexible structure in this study. It has been shown by a series of simulation and experiments that TDC is very effective to suppress the residual vibration of flexible structure induced by its maneuvers.
Park, Seong Je,Lee, Ji Eun,Park, Jean Ho,Lee, Nak Kyu,Lyu, Min-Young,Park, Keun,Koo, Myung Sool,Cho, Sung Hwan,Son, Yong,Park, Suk-Hee Hindawi Limited 2018 Advances In Materials Science And Engineering Vol.2018 No.1
<P>Fused deposition modeling (FDM), one of the archetypal 3D printing processes, typically requires support structures matched to printed model parts that principally have undercut or overhung features. Thus, the support removal is an essential postprocessing step after the FDM process. Here, we present an efficient and rapid method to remove the support part of an FDM-manufactured product using the phenomenon of oxidative degradation of hydrogen peroxide. This mechanism was significantly effective on polyvinyl alcohol (PVA), which has been widely used as a support material in the FDM process. Compared to water, hydrogen peroxide provided a two times faster dissolution rate of the PVA material. This could be increased another two times by applying ultrasonication to the solvent. In addition to the rapidness, we confirmed that amount of the support residues removed was enhanced, which was essentially caused by the surface roughness of the FDM-fabricated part. Furthermore, we demonstrated that there was no deterioration with respect to the mechanical properties or shape geometries of the obtained 3D printed parts. Taken together, these results are expected to help enhance the productivity of FDM by reducing the postprocessing time and to allow the removal of complicated and fine support structures, thereby improving the design capability of the FDM technique.</P>
FDM 3D Printing of Environmental Friendly and High Strength Bio-based PC Filaments for Baby Toys
( Seong Je Park ),( Ji Eun Lee ),( Jean Ho Park ),( Min-young Lyu ),( Keun Park ),( Myung Sool Koo ),( Sun Chul Jin ),( Ki Yong Kim ),( Yong Son ) 한국고무학회 2017 엘라스토머 및 콤포지트 Vol.52 No.2
Due to the depletion of fossil oil and the increasing oil price, bio-plastic is currently topical. Bio-based plastics are synthesized from plant resources, unlike conventional petroleum-based counterparts. Therefore, the former minimizes global warming and reduces carbon dioxide emission. Fossil polycarbonate (PC)has good mechanical and optical properties, but its synthesis requires bisphenol-A and phosgene gas, which are toxic to humans. To address these problems, the fused deposition 3D printing process (hereafter, FDM) is studied using environmentally-friendly and high-strength bio-based PC. A comparisonof the environmental impact and tensile strength of fossil PC versus bio-based PC is presented herein, demonstrating that bio-based PC is more environmentally-friendly with higher tensile strength than fossil PC. The advantages of bio-based PC are applied in the FDM process for the fabrication of environmentally-friendly baby toys.
Effect by acupuncture on hypothalamic expression of maternally separated rats: proteomic approach.
Kim, Hak-Jae,Park, Hae Jeong,Hong, Mee Sook,Song, Jeong Yoon,Park, Hyun-Kyung,Jo, Dae Jean,Park, Sung Wook,HwanYun, Dong,Park, Hun-Kuk,Yang, Jong-Soo,Ban, Ju Yeon,Chung, Joo-Ho Butterworths [etc.] 2010 Neurological research Vol.32 No.suppl1
<P>OBJECTIVES: Early stressors can influence the development of biological and neurological systems. Maternal separation (social isolation) in early life may increase vulnerability to neurodegenerative diseases and neuropsychiatric disorders over the lifespan. To identify new proteins on acupuncture effects in maternally separated rats, an animal model for study of early environmental insults, proteomic approach on the expression of the hypothalamic proteins was performed. METHODS: On post-natal day 14, rat pups were randomly divided into four groups: pups kept with their mothers for 7 days; pups kept with their mothers with acupuncture daily to HT8 (Sobu); maternally separated pups; maternally separated pups with acupuncture. The hypothalamic proteins were analysed by two-dimensional electrophoresis coupled with matrix assisted laser desorption/ionization time-of-flight mass spectrometer. RESULTS: The results showed that 27 spots were differentially and commonly expressed. Of 27 spots, 21 spots were identified while six spots were not, and 15 proteins were known proteins. In maternally separated group, the expressions of 14 proteins were down-regulated, compared to control group. In group of maternally separation with acupuncture, five proteins were down-regulated and nine were up-regulated, compared to the maternally separated group. Among nine proteins up-regulated by acupuncture treatment, we found four proteins (dihydropyrimidinase-like 2, dystrophin-related protein 2, tubulin, alpha 1a and syntaxin 1b) related to neurodevelopment. DISCUSSION: The result suggests that acupuncture to HT8 may affect neurodevelopment, and acupuncture may be a possible therapy for neurodevelopmental disorders.</P>
Ho-kyung Ha,Gyeong-won Nam,Dongwoo Khang,Sung Jean Park,Mee- Ryung Lee,Won-jae Lee 한국축산식품학회 2017 한국축산식품학회지 Vol.37 No.1
The development of a new manufacturing process, a two-step temperature treatment, to modulate the physicochemical properties of nanoparticles including the size is critical. This is because its physicochemical properties can be key factors affecting the cellular uptake and the bioavailability of bioactive compounds encapsulated in nanoparticles. The aims of this study were to produce (beta-lactoglobulin) β-lg nanoparticles and to understand how two-step temperature treatment could affect the formation and physicochemical properties of β-lg nanoparticles. The morphological and physicochemical properties of β-lg nanoparticles were determined using atomic force microscopy and a particle size analyzer, respectively. Circular dichroism spectroscopy was used to investigate the secondary structure of β-lg. The surface hydrophobicity and free thiol groups of β-lg were increased with a decrease in sub-ambient temperature and an increase in mild heat temperature. As sub-ambient temperature was decreased, a decrease in α-helical content and an increase in β-sheet content were observed. The two-step temperature treatment firstly involved a sub-ambient temperature treatment from 5 to 20ºC for 30 min, followed secondly by a mild heat temperature treatment from 55 to 75ºC for 10 min. This resulted in the production of spherically-shaped particles with a size ranging from 61 to 214 nm. Two-way ANOVA exhibited the finding that both sub-ambient and mild heat temperature significantly (p
Resveratrol and piperine enhance radiosensitivity of tumor cells
( Jean Kyoung Tak ),( Jun Ho Lee ),( Jeen Woo Park ) 생화학분자생물학회 2012 BMB Reports Vol.45 No.4
The use of ionizing radiation (IR) is essential for treating many human cancers. However, radioresistance markedly impairs the efficacy of tumor radiotherapy. IR enhances the production of reactive oxygen species (ROS) in a variety of cells which are determinant components in the induction of apoptosis. Much interest has developed to augment the effect of radiation in tumors by combining it with radiosensitizers to improve the therapeutic ratio. In the current study, the radiosensitizing effects of resveratrol and piperine on cancer cells were evaluated. Cancer cell lines treated with these natural products exhibited significantly augmented IR-induced apoptosis and loss of mitochondrial membrane potential, presumably through enhanced ROS generation. Applying natural products as sensitizers for IR-induced apoptotic cell death offers a promising therapeutic approach to treat cancer. [BMB reports 2012; 45(4): 242-246]
Creation of a Hybrid Scaffold with Dual Configuration of Aligned and Random Electrospun Fibers
Park, Suk-Hee,Kim, Min Sung,Lee, Byungjun,Park, Jean Ho,Lee, Hye Jin,Lee, Nak Kyu,Jeon, Noo Li,Suh, Kahp-Yang American Chemical Society 2016 ACS APPLIED MATERIALS & INTERFACES Vol.8 No.4
<P>A novel hybrid construct was developed by combining aligned fibers (AFs) and random fibers (RFs) to form a scaffolding system. Homogeneous fiber-based structures were fabricated by electrospinning, which produced both random and aligned fiber mats depending on the collection method. The upper part of the scaffold contained an AF layer, which possessed a well-organized configuration that provided uniaxial topographic guidance. For mechanical stability and support, the lower part of the scaffold was composed of an RF layer. Despite the presence of randomly distributed RFs, desirable alignment and differentiation could be achieved in cultured C2C12 myoblasts by controlling the density of AF layer. The fibrous structure of the hybrid scaffold also exhibited high porosity and therefore reasonable permeability. Owing to the structural stability provided by the underlying RFs, the cell-laden fibrous scaffolds were amenable to physical manipulation, such as multilayering. Collectively, the morphological features and manipulable architecture of the developed scaffolds suggest that they would perform well in practical applications.</P>
박희승,이준호,김우성,이동석,최성호,오영하,최소진,한서룡,이창렬 대한소화기내시경학회 2000 Clinical Endoscopy Vol.21 No.1
It is very important to be aware of occurrence and distinctive histologic features of gastric glomus tumor because its clinical presentation and endoscopic ficdings are indistinguishable from other gastric tumors. A 58-year-old man was admitted because of intermittent epigastric pain and indigestion for 2 months. Physical examination and laboratory findings revealed within normal limits. Upper gastroendoscopy demonstrated a submucosal mass near the antrum with central mucosal depressionand peripheral multiple erosions. Endoscopic ultrasonography revealed a circumscribed mass that continued to the third and fourth layers which demonstrated a heterogeneous low echo pattern mixed with internal high echo spots. Histologically, the tumor cells have uniform small nuclei with inconspicuous nucleoli. Immunochemical analysis on the tumor cells expressed alpha 1 smooth muscle actin and the tumor cells are enveloped by reticulin fiber, individually or grouped. A case of glomus tumor of the stomach is herein reported with a review of literature.