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Design of Air Turbine and Air Bearing for Dental Handpiece
Pyung Hwang,Sang Shin Park,Jeong L. Sohn,Seong In Kwon,Do Hyung Kim,Woo Seok Kim 한국트라이볼로지학회 2007 한국윤활학회지(윤활학회지) Vol.23 No.5
The design process of the dental handpiece is described. The parameters of the high speed air turbine are estimated. The effect of supply hole on the stiffness and damping of the air bearing for handpiece is studied numerically. The Reynolds equation is solved by using the divergence formulation and the perturbation method. The test rig is built and the test procedure is developed for the turbine rotational speed measurement by using Fourier transform of noise generated by the turbine during steady operation.
T-Type Calcium Channels Are Required to Maintain Viability of Neural Progenitor Cells
Kim, Ji-Woon,Oh, Hyun Ah,Lee, Sung Hoon,Kim, Ki Chan,Eun, Pyung Hwa,Ko, Mee Jung,Gonzales, Edson Luck T.,Seung, Hana,Kim, Seonmin,Bahn, Geon Ho,Shin, Chan Young The Korean Society of Applied Pharmacology 2018 Biomolecules & Therapeutics(구 응용약물학회지) Vol.26 No.5
T-type calcium channels are low voltage-activated calcium channels that evoke small and transient calcium currents. Recently, T-type calcium channels have been implicated in neurodevelopmental disorders such as autism spectrum disorder and neural tube defects. However, their function during embryonic development is largely unknown. Here, we investigated the function and expression of T-type calcium channels in embryonic neural progenitor cells (NPCs). First, we compared the expression of T-type calcium channel subtypes (CaV3.1, 3.2, and 3.3) in NPCs and differentiated neural cells (neurons and astrocytes). We detected all subtypes in neurons but not in astrocytes. In NPCs, CaV3.1 was the dominant subtype, whereas CaV3.2 was weakly expressed, and CaV3.3 was not detected. Next, we determined CaV3.1 expression levels in the cortex during early brain development. Expression levels of CaV3.1 in the embryonic period were transiently decreased during the perinatal period and increased at postnatal day 11. We then pharmacologically blocked T-type calcium channels to determine the effects in neuronal cells. The blockade of T-type calcium channels reduced cell viability, and induced apoptotic cell death in NPCs but not in differentiated astrocytes. Furthermore, blocking T-type calcium channels rapidly reduced AKT-phosphorylation (Ser473) and $GSK3{\beta}$-phosphorylation (Ser9). Our results suggest that T-type calcium channels play essential roles in maintaining NPC viability, and T-type calcium channel blockers are toxic to embryonic neural cells, and may potentially be responsible for neurodevelopmental disorders.
Clinical Experiences of Transforaminal Balloon Decompression for Patients with Spinal Stenosis
( Sung Hoon Kim ),( Won Uk Koh ),( Soo Jin Park ),( Woo Jong Choi ),( Jeong Hun Suh ),( Jeong Gil Leem ),( Pyung Hwan Park ),( Jin Woo Shin ) 대한통증학회 2012 The Korean Journal of Pain Vol.25 No.1
Lumbar spinal stenosis is a commonly treated with epidural injections of local anesthetics and corticosteroids, however, these therapies may relieve Leg pain for weeks to months but do not influence functional status. Furthermore, the majority of patients report no substantial symptom change over the repeated treatment. Utilizing balloon catheters, we successfully treated with three patients who complained persistent symptoms despite repeated conventional steroid injections. Our results suggest that transforaminal decompression using a balloon catheter may have potential in the nonsurgical treatment of spinal stenosis by modifying the underlying pathophysiology. (Korean J Pain 2012; 25: 55-59)
Kim, Jin Woo,Kim, Myung Jin,Kim, Kwang Je,Yun, Hee Jae,Chae, Ji Soo,Hwang, Sang Gil,Chang, Tong-Shin,Park, Hee-Sae,Lee, Kang-Woo,Han, Pyung-Lim,Cho, Ssang-Goo,Kim, Tae-Wan,Choi, Eui-Ju National Academy of Sciences 2005 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF Vol.102 No.40
<P>The transmembrane protein Notch is cleaved by gamma-secretase to yield an active form, Notch intracellular domain (Notch-IC), in response to the binding of ligands, such as Jagged. Notch-IC contributes to the regulation of a variety of cellular events, including cell fate determination during embryonic development as well as cell growth, differentiation, and survival. We now show that Notch1-IC suppresses the scaffold activity of c-Jun N-terminal kinase (JNK)-interacting protein 1 (JIP1) in the JNK signaling pathway. Notch1-IC physically associated with the JNK binding domain of JIP1 and thereby interfered with the interaction between JIP1 and JNK. JIP1 mediated the activation of JNK1 induced by glucose deprivation in mouse embryonic fibroblasts, and ectopic expression of Notch1-IC inhibited JNK activation and apoptosis triggered by glucose deprivation. Taken together, these findings suggest that Notch1-IC negatively regulates the JNK pathway by disrupting the scaffold function of JIP1.</P>
A model for the sound absorption coefficient of multi-layered elastic micro-perforated plates
Kim, Hyun-Sil,Ma, Pyung-Sik,Kim, Sang-Ryul,Lee, Seong-Hyun,Seo, Yun-Ho Academic Press 2018 Journal of Sound and Vibration Vol.430 No.-
<P><B>Abstract</B></P> <P>In this paper, a model for the sound absorption coefficient of multi-layered elastic micro-perforated plates (MPPs) in an impedance tube is developed using an analytical approach. Under the plane wave condition, a low-frequency solution is derived by including the symmetric modes of the plate vibration and the sound pressure field. The sound absorption model derived in this study can handle multi-layered structures composed of any combination of thin elastic plates with or without micro-perforations and rigid MPPs. The effects of the parameters of the plate thickness, hole diameter, perforation ratio, cavity depth, and damping on the sound absorption capabilities are described. For a single MPP, when the perforation ratio is very small, it is observed that the combined effect of the elastic behavior and micro-perforation results in a significant increase of the sound absorption coefficient compared to that of a rigid MPP. However, when the perforation ratio is order of a few percent, the effect of the elastic behavior is negligible compared to that of micro-perforations. Some guidelines for selecting optimum parameters to achieve the maximum average sound absorption coefficient for a given frequency band are discussed for double- and triple-elastic MPPs. It is important to ensure that the perforation ratio of the last MPP is small such that the elastic behavior is dominant, while for the first MPP (and for the second MPP in the triple configuration), the elastic behavior should not be dominant. In addition, maintaining equal cavity depths is beneficial for a high average sound absorption coefficient.</P>
Development of Application Technique of Aluminum Sandwich Sheets for Automotive Hood
Kim, Kee-Joo,Rhee, Meung-Ho,Choi, Byung-Ik,Kim, Cheol-Woong,Sung, Chang-Won,Han, Chang-Pyung,Kang, Ki-Weon,Won, Si-Tae 한국정밀공학회 2009 International Journal of Precision Engineering and Vol.10 No.4
Objective of this study was to develop basic techniques in order to apply aluminum sandwich sheets for an automotive hood part. The aluminum sandwich sheet is the material fabricated by adhering two aluminum skins to one polypropylene core. When it has the same bending stiffness as a steel sheet, it is 65% lighter than the steel sheet and 30% lighter than an aluminum alloy sheet. Therefore, it is notified exclusively as good substitutive materials for a steel body to improve the fuel efficiency. Through aluminum sandwich sheet, however, it has relatively lower formability than that of the steel sheet for automotive application. In this study, we developed application techniques of the aluminum sandwich sheet for automotive hood. The various formability evaluations were carried out in order to secure the fundamental data for the measurement of sheet metal forming and the establishment of optimum application conditions of the sandwich sheet. From these results, it was found that the sandwich sheet could reduce the weight and maintain the flexural rigidity simultaneously comparing to the steel sheet.
CORRELATION BETWEEN THE TENSILE STRENGTH AND CORROSION BEHAVIOR OF HEAT TREATED ZR-1.0NB ALLOY
Kim, Tae-Kyu,Choi, Pyung-Sik,Yang, Sung-Ki,Lee, Chong-Tak,Sohn, Dong-Seong Korean Nuclear Society 2008 Nuclear Engineering and Technology Vol.40 No.6
The correlation between the tensile strength and corrosion behavior of Zr-1.0wt%Nb alloy heat treated at $480^{\circ}C$ for up to 32 hours was evaluated. The tensile strength at $400^{\circ}C$ was continuously reduced with an increasing heat treatment time, mainly due to a grain growth and a decreased area fraction of the precipitates. However, the corrosion resistance in an aqueous ammonia solution at $360^{\circ}C$ was enhanced, mainly due to the formation of $\beta$-Nb precipitates. It is thus concluded that a longer heat treatment time provides a better corrosion resistance while degrading the tensile strength.
Kim, Tae-Kyung,Lee, Jung-Eun,Park, Sun-Kyu,Lee, Kang-Woo,Seo, Ji-Seon,Im, Joo-Young,Kim, Sang-Tae,Lee, Joo-Yong,Kim, Yang-Hee,Lee, Ja-Kyeong,Han, Pyung-Lim Korean Society for Biochemistry and Molecular Bion 2012 Experimental and molecular medicine Vol.44 No.8
Adequate assessment of plaque deposition levels in the brain of mouse models of Alzheimer disease (AD) is required in many core issues of studies on AD, including studies on the mechanisms underlying plaque pathogenesis, identification of cellular factors modifying plaque pathology, and developments of anti-AD drugs. The present study was undertaken to quantitatively evaluate plaque deposition patterns in the brains of the two popular AD models, Tg2576 and Tg-APPswe/PS1dE9 mice. Coronally-cut brain sections of Tg2576 and Tg-APPswe/PS1dE9 mice were prepared and plaque depositions were visualized by staining with anti-amyloid ${\beta}$ peptides antibody. Microscopic images of plaque depositions in the prefrontal cortex, parietal cortex, piriform cortex and hippocampus were obtained and the number of plaques in each region was determined by a computer-aided image analysis method. A series of optical images representing a gradual increase of plaque deposition levels were selected in the four different brain regions and were assigned in each with a numerical grade of 1-6, where +1 was lowest and +6, highest, so that plaques per unit in $mm^2$ increased "sigmoidally" over the grading scales. Analyzing plaque depositions using the photographic plaque reference panels and a computer-aid image analysis method, it was demonstrated that the brains of Tg2576 mice started to accumulate predominantly small plaques, while the brains of Tg-APPswe/PS1dE9 mice deposited relatively large plaques.