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An Sunho,Vo Tam Thuy Lu,Son Taekwon,Choi Hoon,Kim Jinyoung,Lee Juyeon,Kim Byung Hoon,Choe Misun,Ha Eunyoung,Surh Young-Joon,Kim Kyu-Won,Seo Ji Hae 생화학분자생물학회 2023 Experimental and molecular medicine Vol.55 No.-
Human sterile α motif and HD domain-containing protein 1 (SAMHD1) has deoxyribonucleoside triphosphohydrolase (dNTPase) activity that allows it to defend against human immunodeficiency virus type I (HIV-1) infections and regulate the cell cycle. Although SAMHD1 mutations have been identified in various cancer types, their role in cancer is unclear. Here, we aimed to investigate the oncogenic role of SAMHD1 in human clear cell renal cell carcinoma (ccRCC), particularly as a core molecule promoting cancer cell migration. We found that SAMHD1 participated in endocytosis and lamellipodia formation. Mechanistically, SAMHD1 contributed to the formation of the endosomal complex by binding to cortactin. Thereafter, SAMHD1-stimulated endosomal focal adhesion kinase (FAK) signaling activated Rac1, which promoted lamellipodia formation on the plasma membrane and enhanced the motility of ccRCC cells. Finally, we observed a strong correlation between SAMHD1 expression and the activation of FAK and cortactin in tumor tissues obtained from patients with ccRCC. In brief, these findings reveal that SAMHD1 is an oncogene that plays a pivotal role in ccRCC cell migration through the endosomal FAK-Rac1 signaling pathway.
( Sunho Park ),( Daun Kim ),( Dohyeon Lee ),( Woochan Kim ),( Jangho Kim ) 한국농업기계학회 2017 한국농업기계학회 학술발표논문집 Vol.22 No.2
Eggshell membrane (ESM), one of the agricultural bioresources, is being recognized as emerging engineering platforms in various fields including agriculture and biological engineering. Eggshell membrane is the proteinrich membrane between the eggshell and egg white, having interesting characteristics such as structural, chemical, and physical properties. However, the raw ESM has some disadvantages (e.g., limited physical, mechanical, electrical, and chemical properties), which raised some problems for its wide use as commercial engineering platforms. Here, we present new ESM-based engineering platforms based on nanotechnology. To develop the nanotopographically-enhanced ESM platforms, we used graphene, one of the carbon-based nanomaterials, that can provide unique nanotopographically-defined cues to the raw ESM to enhance its performance. The graphene- ESM hybrid platforms showed hierarchically micro- and nanoscale structure (e.g., microfibers from ESM and nanowrinkle from graphene). It is also found that the graphene-ESM hybrid platforms could enhance the various property compared to the raw ESM. In addition, we report our ongoing work to develop novel ESM-based nanopatterned engineering platforms based on capillary force lithography. Our approach can enable the design and manipulation of ESM-based functional engineering platforms for various applications such as agricultural, biological, environmental, and biomedical platforms (e.g., biomaterials, electric devices, sensors, air purification systems).
Application of Superconducting Flywheel Energy Storage System to Inertia-Free Stand-Alone Microgrid
SunHo Bae,DongHee Choi,Jung-Wook Park,Soo Hyoung Lee 대한전기학회 2017 Journal of Electrical Engineering & Technology Vol.12 No.4
Recently, electric power systems have been operating with tight margins and have reached their operational limits. Many researchers consider a microgrid as one of the best solutions to relieve that problem. The microgrid is generally powered by renewable energies that are connected through power converters. In contrast to the rotational machines in the conventional power plants, the converters do not have physical rotors, and therefore they do not have rotational inertia. Consequently, a stand-alone microgrid has no inertia when it is powered by the only converter-based-generators (CBGs). As a result, the relationship between power and frequency is not valid, and the grid frequency cannot represent the power balance between the generator and load. In this paper, a superconducting flywheel energy storage system (SFESS) is applied to an inertia-free stand-alone (IFSA) microgrid. The SFESS accelerates or decelerates its rotational speed by storing or releasing power, respectively, based on its rotational inertia. Then, power in the IFSA microgrid can be balanced by measuring the rotor speed in the SFESS. This method does not have an error accumulation problem, which must be considered for the state of charge (SOC) estimation in the battery energy storage system (BESS). The performance of the proposed method is verified by an electromagnetic transient (EMT) simulation.
Dynamic Compressed Representation of Texts with Rank/Select
Sunho Lee,Kunsoo Park 한국정보과학회 2009 Journal of Computing Science and Engineering Vol.3 No.1
Given an n-length text T over a σ-size alphabet, we present a compressed representation of T which supports retrieving queries of rank/select/access and updating queries of insert/delete. For a measure of compression, we use the empirical entropy H(T), which defines a lower bound nH(T) bits for any algorithm to compress T of n log σ bits. Our representation takes this entropy bound of T, i.e., nH(T) ≤ n log σ bits, and an additional bits less than the text size, i.e., o(n log σ) + O(n) bits. In compressed space of nH(T) + o(n log σ) + O(n) bits, our representation supports O(log n) time queries for a log n-size alphabet and its extension provides O((1+logσ/log log n) log n) time queries for a σ-size alphabet.
Full Scale Performance Prediction of an Energy Saving Device by Using Computational Fluid Dynamics
Sunho Park,Gwangho Oh,Shin Hyung Rhee 한국전산유체공학회 2014 한국전산유체공학회 학술대회논문집 Vol.2014 No.10
Recently interest on energy saving devices (ESD’s) has increased with the enforcement of the energy efficiency design index (EEDI) verification proposed by the international maritime organization (IMO). Extension of propulsive performance results from model to full scale ships plays an important role in verification of ships with ESD’s. The present study proposed a reliable and efficient propulsive performance prediction method for full scale ships with ESD’s. The propulsive performance prediction in full scale KVLCC2 with pre-swirl stator (PSS) was conducted by the proposed method. Its results were then compared with those by the existing extension methods and by full scale CFD computations. From the results, it was confirmed that the proposed method could extend the model scale results to full scale ones with ESD’s performance improvement effects. Unlike the existing methods, it takes into account of ESD’s and consumes much less computational resources and time than full scale CFD computations.
Pilot Interference Cancellation in a WCDMA wireless Repeater
Sunho Kim,Sungbin Im 대한전자공학회 2008 ITC-CSCC :International Technical Conference on Ci Vol.2008 No.7
In this paper, we propose a mitigation method to reduce the effect of pilot interference at the wireless repeater. Using an adaptive estimation algorithm, we estimates undesired pilot signals from neighboring base stations and eliminate these interference signals from the received signals. This approach is based on the conventional pilot signal cancellation techniques for a user equipment. This improves the signal to interference ratio (SIR), and enables increased cell capacity and/or better bits error rates (BER) performance in the wideband code division multiple access (WCDMA) systems. Simulation studies have been carried out to verify the proposed approach and promising results are observed.
Sunho Park,Hyun-Ha Park,Woochan Kim,Yonghyun Gwon,Hoon Eui Jeong,Jangho Kim 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.11
Aligned nanotopography including nanopattern, nanoneedle, and nanowire hold strong potential to regulate stem cell behaviors. In this study, we present a highly flexible hydrogel nanospike array as a precisely defined, vertically aligned polymeric platform for enhancing the differentiation of stem cells and efficiently suppressing biofilm. This vertical nanostructure not only imposes a strong physical stimulus to the cells but also leads to a three-dimensional spherical morphology of the cells, which remarkably promotes their osteogenic differentiation and secretion of growth factors. At the same time, it shows efficient biofilm resistance. This multifunctional flexible hydrogel platform with its vertical nanoarchitectures can be used as transplantable stem cell scaffold or biomedical implant with enhanced stem cell and anti-pathogenic functions.