• Molecules and Cells
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• 제44권5호
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• pp.342-355
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• 2021

The microphthalmia-associated transcription factor family (MiT family) proteins are evolutionarily conserved transcription factors that perform many essential biological functions. In mammals, the MiT family consists of MITF (microphthalmia-associated transcription factor or melanocyte-inducing transcription factor), TFEB (transcription factor EB), TFE3 (transcription factor E3), and TFEC (transcription factor EC). These transcriptional factors belong to the basic helix-loop-helix-leucine zipper (bHLH-LZ) transcription factor family and bind the E-box DNA motifs in the promoter regions of target genes to enhance transcription. The best studied functions of MiT proteins include lysosome biogenesis and autophagy induction. In addition, they modulate cellular metabolism, mitochondria dynamics, and various stress responses. The control of nuclear localization via phosphorylation and dephosphorylation serves as the primary regulatory mechanism for MiT family proteins, and several kinases and phosphatases have been identified to directly determine the transcriptional activities of MiT proteins. In different immune cell types, each MiT family member is shown to play distinct or redundant roles and we expect that there is far more to learn about their functions and regulatory mechanisms in host defense and inflammatory responses.

• 한국자기공명학회논문지
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• 제21권3호
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• pp.78-84
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• 2017

Pseudin is a naturally occurring 24 amino-acid-residue antimicrobial peptide derived from the skin of paradoxical frog Pseud's paradoxa. It shows potency against the bacteria and antibiotic-resistant bacteria strain, but has high cytotoxicity against mammalian cell. In our previous study, substitution of $Pro^{11}$ for Gly (Ps-P) increased bacterial cell selectivity but decreased the antibacterial activity of pseudin. In this study, we designed pseudin analogue, Ps-4K-P with increased cationicity up to +7 in Ps-P by substituting Glu14, Gln10, Gln24, and Leu18 with Lys. Ps-4K-P showed improved potent antibacterial activity with high bacterial cell selectivity. We determined the tertiary structure of Ps-4K-P in the presence of DPC micelles by NMR spectroscopy and it has a hinge structure at $Pro^{11}$ followed by three turn helices from $Pro^{11}$ to $Val^{23}$ at the C-terminus. Amphipathicity with increased cationicity as well as helix-hinge-helix structural motif provided by introduction of a Pro at position $Gly^{11}$ are the crucial factors which confer antibacterial activity with bacterial cell selectivity to Ps-4K-P.

• Structural Engineering and Mechanics
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• 제87권6호
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• pp.585-599
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• 2023

Geopolymer concrete (GC) can be competently utilized as a practical replacement for cement to prevent a high carbon footprint and to give a direction toward sustainable concrete construction. Moreover, previous studies mostly focused on the axial response of glass fiber reinforced polymer (glass-FRP) concrete compressive elements without determining the effectiveness of repairing them after their partial damage. The goal of this study is to assess the structural effectiveness of partially damaged GC columns that have been restored using carbon fiber reinforced polymer (carbon-FRP). Bars made of glass-FRP and helix made of glass-FRP are used to reinforce these columns. For comparative study, six of the twelve circular specimens-each measuring 300 mm×1200 mm-are reinforced with steel bars, while the other four are axially strengthened using glass-FRP bars (referred to as GSG columns). The broken columns are repaired and strengthened using carbon-FRP sheets after the specimens have been subjected to concentric and eccentric compression until a 30% loss in axial strength is attained in the post-peak phase. The study investigates the effects of various variables on important response metrics like axial strength, axial deflection, load-deflection response, stiffness index, strength index, ductility index, and damage response. These variables include concentric and eccentric compression, helix pitch, steel bars, carbon-FRP wrapping, and glass-FRP bars. Both before and after the quick repair process, these metrics are evaluated. The results of the investigation show that the axial strengths of the reconstructed SSG and GSG columns are, respectively, 15.3% and 20.9% higher than those of their original counterparts. In addition, compared to their SSG counterparts, the repaired GSG samples exhibit an improvement in average ductility indices of 2.92% and a drop in average stiffness indices of 3.2%.

• 대한수학회보
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• 제52권3호
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• pp.963-975
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• 2015

In this paper, we give a representation formula for an isotropic curve with pseudo arc length parameter and define the structure function of such curves. Using the representation formula and the Frenet formula, the isotropic Bertrand curve and k-type isotropic helices are characterized in the 3-dimensional complex space $\mathbb{C}^3$.

• 한국전자파학회논문지
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• 제27권10호
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• pp.883-891
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• 2016

본 논문에서는 금속 케이스를 접지 방사체로 활용한 비대칭 다이폴 안테나를 제안하고, 이를 ISM 대역(2.4~2.48 GHz)에서 동작하는 펜타입 무선 프리젠터에 적용하였다. 제안한 비대칭 다이폴 안테나는 긴 원통 모양의 금속 케이스 상단에 수직모드 헬리컬 코일이 장착된 구조로, 접지면인 금속 케이스를 방사소자로 동작하게 하여 헬리컬 안테나의 좁은 대역폭과 낮은 이득을 증가시켰다. 또한, 특수 제작된 인체 팬텀을 사용하여 사람이 무선 프리젠터의 금속 케이스를 손으로 잡을 때 안테나의 성능에 미치는 영향을 분석하였다. 측정 결과, 제안한 안테나는 자유공간에서 반사손실 -10 dB를 기준으로 2.3~2.5 GHz까지 200 MHz의 대역폭을 가지며, 5 dBi의 최대이득을 나타내었다. 사람 손이 금속 케이스에 접촉한 경우에는 2.24~2.72 GHz까지 480 MHz의 대역폭이 측정되었고, 최대이득은 3 dB만큼 낮아진 2 dBi로 측정되었다.

• Kyungpook Mathematical Journal
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• 제63권2호
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• pp.263-285
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• 2023

In this paper, we investigate the spherical indicatrices of a new relationship between Bertrand pair curves in Euclidean 3-space. We obtain necessary and sufficient conditions for this type of Bertrand pair curves to be slant helix, and provide an example.

• 정보처리학회논문지:소프트웨어 및 데이터공학
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• 제3권4호
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• pp.163-168
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• 2014

단백질 분자 내에서 ${\alpha}$-헬릭스는 단백질의 구조나 기능, 그리고 다른 단백질과의 결합, 활성 조절 등에 있어 중요한 역할을 하며, 이에 따라 헬릭스에 대한 구조적인 분석이 연구되어 왔다. ${\alpha}$-헬릭스는 그 중심축을 기준으로 다른 ${\alpha}$-헬릭스와의 상호위치를 평가하기 때문에 길게 휘어지거나 꺾인 ${\alpha}$-헬릭스들을 한 개의 헬릭스로 해석할 경우에는 단백질의 구조 분석에 있어서 상당한 오차가 발생할 수 있다. 본 논문에서는 PDB 파일 내에 표시된 단백질 분자의 ${\alpha}$-헬릭스를 주어진 오차 범위 내에서 여러 개의 곧은 형태의 헬릭스로 재구성하는 알고리즘을 제안한다.

• Steel and Composite Structures
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• 제21권3호
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• pp.573-588
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• 2016

Carbon Fiber Reinforced Plastic (CFRP) and Titanium Alloy (Ti6Al4V) stack, extensively used in aerospace structural components are assembled by fasteners and the holes are made using drilling process. Drilling of stack in one shot is a complicated process due to dissimilarity in the material properties. It is vital to have optimal machining condition and tool geometry for better hole quality and tool life. In this study the tool wear and hole quality were analysed by experimental analysis using three modified twist drills and online tool condition monitoring using Acoustics Emission (AE) sensor. Helix angle and point angle influence tool performance and cutting force. It was found that a tool geometry (TG1) with high helix angle of $35^{\circ}$ with low point angle $130^{\circ}$ results in reduction in thrust force of 150-500 N range but the TG2 also perform almost similar to TG1, but when compared with the AErms voltage generated during drilling it was found that progressive rise in voltage in TG1 is less with respect to TG2 which can be attributed to tool life. In process wear monitoring was done using crest factor as monitoring index. AErms voltage were measured and correlated with the performance of the drills.

• Steel and Composite Structures
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• 제21권3호
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• pp.605-628
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• 2016

The energy absorption characteristics of diamond core sandwich cylindrical columns under axial crushing process depend greatly on the amount of material which participates in the plastic deformation. Both the single-objective and multi-objective optimizations are performed for columns under axial crushing load with core thickness and helix pitch of the honeycomb core as design variables. Models are optimized by multi-objective particle swarm optimization (MOPSO) algorithm to achieve maximum specific energy absorption (SEA) capacity and minimum peak crushing force (PCF). Results show that optimization improves the energy absorption characteristics with constrained and unconstrained peak crashing load. Also, it is concluded that the aluminum tube has a better energy absorption capability rather than steel tube at a certain peak crushing force. The results justify that the interaction effects between the honeycomb and column walls greatly improve the energy absorption efficiency. A ranking technique for order preference (TOPSIS) is then used to sort the non-dominated solutions by the preference of decision makers. That is, a multi-criteria decision which consists of MOPSO and TOPSIS is presented to find out a compromise solution for decision makers. Furthermore, local and global sensitivity analyses are performed to assess the effect of design variable values on the SEA and PCF functions in design domain. Based on the sensitivity analysis results, it is concluded that for both models, the helix pitch of the honeycomb core has greater effect on the sensitivity of SEA, while, the core thickness has greater effect on the sensitivity of PCF.

• Bulletin of the Korean Chemical Society
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• 제30권3호
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• pp.623-629
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• 2009

We have performed replica-exchange molecular dynamics simulations on 41 residue peptide mainly composed of NAC (non A$\beta$ component) sequence in $\alpha$-Synuclein. To investigate conformational characteristics of intrinsically unstructured peptides, we carried out structural analysis on the ‘representative structures’ for ensemble of structures occurring at different temperatures. The secondary structure profile obtained from our simulations suggests that the NAC region of $\alpha$-synuclein can be divided into roughly three helical-like segments. It is found that the overall helix-turn-helix like topology is conserved even though the conformational fluctuations grow as the temperature increases. The coordinate-based and the distance-based representative structures exhibit noticeable differences at higher temperatures while they are similar at lower temperatures. It is found that structural variations for the coordinate-based representative structures are much larger, suggesting that distance-based representative structures provide more reliable information concerning characteristic features of intrinsically unstructured proteins. The present analysis also indicates that the conformational features of representative structures at high temperatures might be related to those in membrane or low pH environment.