A Study on the Manufacturing of Large Size Hollow Shape Parts for Prototype-Car Using Rapid Prototyping Technology and Vacuum Molding

Rapid Prototyping(RP) techniques have revolutionized traditional manufacturing methods. These techniques allow the user to fabricate a part directly from a conceptual model before investing in production tooling and help develop new models with significant short time. This paper suggests the new process to manufacture large size hollow shape parts for prototype-car using Rapid Prototyping technology and Vacuum Molding with the reduction of delivery time. In addition, this paper introduces the dividing and combining method to make large size RP master model in spite of the limit of the build chamber dimensions of commercialized RP systems and post-processing method to achieve sufficient surface quality.Mechanical Engineerin

Hybrid star HD 81817 accompanied by brown dwarf or substellar companion

HD 81817 is known as a hybrid star. Hybrid stars have both cool stellar wind properties and Ultraviolet (UV) or even X-ray emission features of highly ionized atoms in their spectra. A white dwarf companion has been suggested as the source of UV or X-ray features. HD 81817 has been observed since 2004 as a part of a radial velocity (RV) survey program to search for exoplanets around K giant stars using the Bohyunsan Observatory Echelle Spectrograph at the 1.8 m telescope of Bohyunsan Optical Astronomy Observatory in Korea. We obtained 85 RV measurements between 2004 and 2019 for HD 81817 and found two periodic RV variations. The amplitudes of RV variations are around 200 m s^-1, which are significantly lower than that expected from a closely orbiting white dwarf companion. Photometric data and relevant spectral lines were also analyzed to help determine the origin of the periodic RV variations. We conclude that 627.4-day RV variations are caused by intrinsic stellar activities such as long-term pulsations or rotational modulations of surface activities based on H{\alpha} equivalent width (EW) variations of a similar period. On the other hand, 1047.1-day periodic RV variations are likely to be caused by a brown dwarf or substellar companion, which is corroborated by a recent GAIA proper motion anomaly for HD 81817. The Keplerian fit yields a minimum mass of 27.1 M_Jup, a semimajor axis of 3.3 AU, and an eccentricity of 0.17 for the stellar mass of 4.3 M_sun for HD 81817. The inferred mass puts HD 81817 b in the brown dwarf desert

Akt regulates the expression of MafK, synaptotagmin I, and syntenin-1, which play roles in neuronal function

<p>Abstract</p> <p>Background</p> <p>Akt regulates various cellular processes, including cell growth, survival, and metabolism. Recently, Akt's role in neurite outgrowth has also emerged. We thus aimed to identify neuronal function-related genes that are regulated by Akt.</p> <p>Methods</p> <p>We performed suppression subtractive hybridization on two previously established PC12 sublines, one of which overexpresses the wild-type (WT) form and the other, the dominant-negative (DN) form of Akt. These sublines respond differently to NGF's neuronal differentiation effect.</p> <p>Results</p> <p>A variety of genes was identified and could be classified into several functional groups, one of which was developmental processes. Two genes involved in neuronal differentiation and function were found in this group. v-Maf musculoaponeurotic fibrosarcoma oncogene homolog K (MafK) induces the neuronal differentiation of PC12 cells and immature telencephalon neurons, and synaptotagmin I (SytI) is essential for neurotransmitter release. Another gene, <it>syntenin-1 </it>(<it>Syn-1</it>) was also recognized in the same functional group into which <it>MafK </it>and <it>SytI </it>were classified. Syn-1 has been reported to promote the formation of membrane varicosities in neurons. Quantitative reverse transcription polymerase chain reaction analyses show that the transcript levels of these three genes were lower in PC12 (WT-Akt) cells than in parental PC12 and PC12 (DN-Akt) cells. Furthermore, treatment of PC12 (WT-Akt) cells with an Akt inhibitor resulted in the increase of the expression of these genes and the improvement of neurite outgrowth. These results indicate that dominant-negative or pharmacological inhibition of Akt increases the expression of <it>MafK</it>, <it>SytI</it>, and <it>Syn-1 </it>genes. Using lentiviral shRNA to knock down endogenous Syn-1 expression, we demonstrated that Syn-1 promotes an increase in the numbers of neurites and branches.</p> <p>Conclusions</p> <p>Taken together, these results indicate that Akt negatively regulates the expression of <it>MafK</it>, <it>SytI</it>, and <it>Syn-1 </it>genes that all participate in regulating neuronal integrity in some way or another.</p

Effects of insertion angle and implant thread type on the fracture properties of orthodontic mini-implants during insertion

Objective: To determine the effects of insertion angle (IA) and thread type on the fracture properties of orthodontic mini-implants (OMIs) during insertion. Materials and Methods: A total of 100 OMIs (self-drilling cylindrical; 11 mm in length) were allocated into 10 groups according to thread type (dual or single) and IA (0 degrees, 8 degrees, 13 degrees, 18 degrees, and 23 degrees) (n = 10 per group). The OMIs were placed into artificial materials simulating human tissues: two-layer bone blocks (Sawbones), root (polymethylmethacrylate stick), and periodontal ligament (Imprint-II Garant light-body). Maximum insertion torque (MIT), total insertion energy (TIE), and peak time (PT) were measured and analyzed statistically. Results: There were significant differences in MIT, TIE, and PT among the different IAs and threads (all P<.001). When IA increased, MIT increased in both thread groups. However, TIE and PT did not show significant differences among 0 degrees, 8 degrees, and 13 degrees IAs in the dual-thread group or 8 degrees, 13 degrees, and 18 degrees IAs in the single-thread group. The dual-thread groups showed higher MIT at all IAs, higher TIE at 0 degrees and 23 degrees IAs, and longer PT at a 23 degrees IA than the single-thread groups. In the 0 degrees, 8 degrees, and 13 degrees IA groups, none of the OMIs fractured or became deformed. However, in the 18 degrees IA group, all the OMIs were fractured or deformed. Dual-thread OMIs showed more fracturing than deformation compared to single-thread OMIs (P < .01). In the 23 degrees IA group, all OMIs penetrated the artificial root without fracturing and deformation. Conclusions: When OMIs contact artificial root at a critical contact angle, the deformation or fracture of OMIs can occur at lower MIT values than those of penetration.OAIID:oai:osos.snu.ac.kr:snu2013-01/102/0000004298/8SEQ:8PERF_CD:SNU2013-01EVAL_ITEM_CD:102USER_ID:0000004298ADJUST_YN:YEMP_ID:A072100DEPT_CD:852CITE_RATE:1.184FILENAME:조일식-백승학.pdfDEPT_NM:치의과학과SCOPUS_YN:YCONFIRM:

Initial adhesion of bone marrow stromal cells to various bone graft substitutes

Purpose: The aim of this study is to determine whether certain biomaterials have the potential to support cell attachment. After seeding bone marrow stromal cells onto the biomaterials, we investigated their responses to each material in vitro. Methods: Rat bone marrow derived stromal cells were used. The biomaterials were deproteinized bovine bone mineral (DBBM), DBBM coated with fibronectin (FN), synthetic hydroxyapatite (HA), HA coated with FN, HA coated with beta-tricalcium phosphate (TCP), and pure beta-TCP. With confocal laser scanning microscopy, actin filaments and vinculin were observed after 6, 12, and 24 hours of cell seeding. The morphological features of cells on each biomaterial were observed using scanning electron microscopy at day 1 and 7. Results: The cells on HA/FN and HA spread widely and showed better defined actin cytoskeletons than those on the other biomaterials. At the initial phase, FN seemed to have a favorable effect on cell adhesion. In DBBM, very few cells adhered to the surface. Conclusions: Within the limitations of this study, we can conclude that in contrast with DBBM not supporting cell attachment, HA provided a more favorable environment with respect to cell attachment. (C) 2011 Korean Academy of Periodontology.This work was supported by a National Research Foundation of Korea Grant funded by the Government of the Republic of Korea (2008-E00580)

Prevalence of sarcopenia and sarcopenic obesity in Korean adults: The Korean Sarcopenic Obesity Study (KSOS)

*Context:* Sarcopenic obesity (SO), a combination of excess weight and reduced muscle mass and/or strength, is suggested to be associated with an increased risk of adverse health outcomes. &#xd;&#xa;*Objectives:* To examine the prevalence and characteristics of Sarcopenic and SO defined by using different indices such as Appendicular Skeletal muscle Mass (ASM)/height^2^ and Skeletal Muscle Index (SMI (%): skeletal muscle mass (kg)/weight (kg) &#xd7; 100) for Korean adults. &#xd;&#xa;*Methods:* 591 participants were recruited from the Korean Sarcopenic Obesity Study (KSOS) which is an ongoing prospective observational cohort study. Analysis was conducted in 526 participants (328 women, 198 men) who had complete data on body composition using Dual X-ray absorptiometry and computed tomography. &#xd;&#xa;*Results:* The prevalence of sarcopenia and SO increases with aging. Using two or more standard deviations (SD) of ASM/height^2^ below reference values from young, healthy adults as a definition of sarcopenia, the prevalence of sarcopenia and SO was 6.3% and 1.3% in men and 4.1% and 1.7% in women over 60 years of age. However, using two or more SD of SMI, the prevalence of sarcopenia and SO was 5.1% and 5.1% respectively in men and 14.2% and 12.5% respectively in women. As defined by SMI, subjects with SO had 3 times the risk of metabolic syndrome (OR = 3.03, 95% confidence interval (CI) = 1.26-7.26) and subjects with non-sarcopenic obesity had approximately 2 times the risk of metabolic syndrome (OR = 1.89, 95% CI = 1.18-3.02) compared with normal subjects. &#xd;&#xa;*Conclusion:* Obese subjects with relative sarcopenia were associated with a greater likelihood for metabolic syndrome. As Koreans were more obese and aging, the prevalence of SO and its impact on health outcomes are estimated to be rapidly grow. Further research is requested to establish the definition, cause and consequences of SO.&#xd;&#xa

Spatial and temporal variabilities of spring Asian dust events and their impacts on chlorophyll-a concentrations in the western North Pacific Ocean

Author Posting. © American Geophysical Union, 2017. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 44 (2017): 1474–1482, doi:10.1002/2016GL072124.As the western North Pacific Ocean is located downwind of the source regions for spring Asian dust, it is an ideal location for determining the response of open waters to these events. Spatial analysis of spring Asian dust events from source regions to the western North Pacific, using long-term daily aerosol index data, revealed three different transport pathways supported by the westerly wind system: one passing across the northern East/Japan Sea (40°N–50°N), a second moving over the entire East/Japan Sea (35°N–55°N), and a third flowing predominantly over the Siberian continent (>50°N). Our results indicate that strong spring Asian dust events can increase ocean primary productivity by more than 70% (>2-fold increase in chlorophyll-a concentrations) compared to weak/nondust conditions. Therefore, attention should be paid to the recent downturn in the number of spring Asian dust events and to the response of primary production in the western North Pacific to this change.Korean government (MSIP) Grant Numbers: 2015R1C1A1A01052051, NRF-C1ABA001-2011-0021064; Korea Polar Research Institute (KOPRI) Grant Number: PE17030; NOAA Grant Number: NA11OAR4310063; WHOI2017-08-1

Root and bone response to the proximity of a mini-implant under orthodontic loading

Objective: To determine the histological reaction of the root and bone as a mini-implant approaches the root. Materials and Methods: Two kinds of mini-implants were inserted into the buccal alveolar bone of 4 beagles (2 males and 2 females). The specimens were classified as the near-root group, the PDL contact group, the root contact group, and the root perforation group. Cementum resorption, dentin resorption, cementum repair, cementum growth, ankylosis, root cracking, and root fracture were assessed as the implant neared the root. Results: The incidence of root resorption increased when the mini-implant was less than 0.6 mm from the root in the near-root group and PDL contact group. Root cracking and root fracture occurred in the root contact group and root perforation group. Bone resorption and ankylosis were observed in some specimens. However, some specimens of the PDL contact group and root contact group had cementum growth or little root resorption despite proximity to the root. In the root perforation group, root resorption and ankylosis occurred on the side opposite the insertion. Conclusions: There is a risk of root contact and severe tissue damage from a thick mini-implant and the drilling procedure, either of which can induce root resorption or ankylosis. Use of smaller mini-implants may reduce root contact and tissue damage. However, the small mini-implant may need enhancement of its stability.This study was supported by grant number 11-2009-013 from the SNUBH Research Fund

Cerebellar Hypoperfusion during Transient Global Amnesia: An MRI and Oculographic Study

Background and Purpose Transient global amnesia (TGA) is characterized by sudden anterograde and retrograde amnesia lasting for LIP to 24 hours. Diffusion-weighted magnetic resonance imaging (DWI) in cases of TGA and ischemia demonstrates a high frequency of high signal intensities restricted to the hippocampus, and this has been proposed as an etiology of TGA. The aims of this study were to characterize the DWI and single-photon-emission computed tomography (SPECT) findings during the acute and recovered phases of TGA and to correlate the findings with oculomotor abnormalities. Methods Five consecutive patients with a clinical diagnosis of TGA underwent DWI and SPECT of the brain within 24 hours after symptom onset and again 3 days later. Eye movements were also recorded using three-dimensional video-oculography. Results In all patients, DWI disclosed small punctuate (1-3 mm), high-signal lesions in the lateral portion of the hippocampus. The initial SPECT also revealed hypoperfusion in the cerebellar vermis, which had recovered by the follow-up examination. Three patients showed saccadic hypermetria or impaired smooth pursuit only during the acute phase. Conclusions Our patients with TGA showed cerebellar vermian hypoperfusion in addition to ischemic insults to the lateral hippocampus. The oculomotor abnormalities observed in our patients support the Occurrence of cerebellar dysfunction during the TGA attack. J Clin Neurol 2009;5:74-80This study was supported by a grant of the Korean Health 21 R&D Project, Ministry of Health and Welfare, Republic of Korea (no. A050079).Yang Y, 2008, J CLIN NEUROL, V4, P59Sander K, 2005, LANCET NEUROL, V4, P437Lampl Y, 2004, ACTA NEUROL SCAND, V110, P75Tong DC, 2004, NEUROLOGY, V62, P2154Takeuchi R, 2004, EUR J NUCL MED MOL I, V31, P578, DOI 10.1007/s00259-003-1406-8Teicher MH, 2003, NEUROSCI BIOBEHAV R, V27, P33, DOI 10.1016/S0149-7634(03)00007-1Anderson CM, 2002, PSYCHONEUROENDOCRINO, V27, P231Asada T, 2000, PSYCHIAT CLIN NEUROS, V54, P691Pantoni L, 2000, ACTA NEUROL SCAND, V102, P275Jovin TG, 2000, J NEUROIMAGING, V10, P238Warren JD, 2000, J CLIN NEUROSCI, V7, P57Levitt JJ, 1999, AM J PSYCHIAT, V156, P1105Loeber RT, 1999, SCHIZOPHR RES, V37, P81Giedd JN, 1999, PROG NEURO-PSYCHOPH, V23, P571SCHMAHMANN JD, 1999, MOVEMENT DISORDERSBerquin PC, 1998, NEUROLOGY, V50, P1087Schmidtke K, 1998, J NUCL MED, V39, P155Ghelarducci B, 1997, ARCH ITAL BIOL, V135, P369HODGES JR, 1994, J NEUROL NEUROSUR PS, V57, P605HODGES JR, 1990, J NEUROL NEUROSUR PS, V53, P834HODGES JR, 1990, BRAIN, V113, P639HEATH RG, 1976, J NEUROL NEUROSUR PS, V39, P1037