• Journal of the Computational Structural Engineering Institute of Korea
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• v.24 no.1
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• pp.55-60
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• 2011

In the present work, isogeometric analysis in linear elasticity problem is conducted using the basis functions from NURBS. The objectives of isogeometric analysis introduced is to integrate both geometric modeling(CAD) and computational analysis(CAE), and this can be accomplished from direct usage of geometric modeling by NURBS as the computational mesh. The merit of the isogeometry analysis is that NURBS surface are able to represent exact geometry from the control points and knot vectors, and also subsequent refinement is relatively simple relatively. In order to verify the computer codes developed in this study, it has been applied to two structural models of which geometry are simple ; 1) circular cylinder subjected to the constant internal pressure loading, 2) square plate with circular hole at center subjected to uniform tension. The exact solutions of these two models are available. Convergence of the approximate solutions by the present code for the isogeometry analysis are investigated by mesh refinement with inserting knots (h-refinement) and by mesh refinement with order elevation of the basis functions (p-refinement).

• Journal of Sensor Science and Technology
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• v.30 no.4
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• pp.229-235
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• 2021

This study presents a simple approach for the assembly of a free-standing conductive electronic nanofilm of single-walled carbon nanotubes (SWNTs) suitable for enzymatic electrochemical biosensors. A large-scale SWNT electronic film was successfully produced by the dialysis of p-Terphenyl-4,4''-dithiol (TPDT)-treated SWNTs. Furthermore, Horseradish peroxidase (HRP) was immobilized on the TPDT-SWNT electronic film, and the enzymatic detection of hydrogen peroxide (H₂O₂) was demonstrated without mediators. The detection of H₂O₂ in the negative potential range (-0.4 V vs. Ag/AgCl) was achieved by direct electron transfer of heme-based enzymes that were immobilized on the TPDT-SWNT electronic film. The SWNT-based biosensor exhibited a wide detection range of H₂O₂ from 10 µM to 10 mM. The HRP-doped SWNT electronic film achieved a high sensitivity of 342 ㎛A/mM·cm² and excellent selectivity against a variety of redox-active interfering substances, such as ascorbic acid, uric acid, and acetaminophen.

• Applied Chemistry for Engineering
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• v.30 no.1
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• pp.114-121
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• 2019

In this study, antioxidative, antibacterial and cytoprotective effects of the ethanol extract and ethylacetate fraction of Lycopus lucidus (L. lucidus) were compared and analyzed. Free radical scavenging activities ($FSC_{50}$) of the L. lucidus extract and fraction were found to be 65.1 and $64.9{\mu}g/mL$ respectively. In the $Fe^{3+}-EDTA/H_2O_2$ system, the reactive oxygen species (ROS) scavenging activities ($OSC_{50}$) for the extract and fraction were 6.6 and $6.3{\mu}g/mL$, respectively which showed excellent total antioxidant abilities. The extract showed antibacterial activity against S. aureus, while the fraction showed in all the bacteria except for A. niger. The cytoprotective effect of L. lucidus extract was compared to that of the fraction and the effect against $^1O_2$-induced cellular damage of human erythrocytes (${\tau}_{50}$) was 51.3 and 73.7 min at $50{\mu}g/mL$, respectively. For the cytoprotective effect of keratinocytes damaged by $H_2O_2$ and UVB, the extracts did not show any efficacy but showed efficacy at $1-2{\mu}g/mL$, respectively. The fraction increased the cell viability up to 85.8 and 81.9%, respectively. As a result of intracellular ROS scavenging activity, the scavenging activity was observed at $1-2{\mu}g/mL$ of the fraction. From the results comparing the physiological activities of L. lucidus extract and the fraction, the ethylacetate fraction of L. lucidus has antioxidative effect similar to that of the extract whereas superior antimicrobial and cytoprotective effects than that of the extract. Overall, the ethylacetate fraction of L. lucidus protects cells from an external stress which can be used as a potential cosmetic material.

• Korean Journal of Crystallography
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• v.4 no.2
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• pp.54-62
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• 1993

The crystal shnture of dehydrated fully Cd2+-exchanged zeolite A evacuated at 2 × 10-6 Torr and 650℃ (a:12.189(2) A) and of its iodine sorption corrplex (a:12.168(2)A) have been netsmlmn by single uystal x-ray diffraction techliques in the cubic space group hkTn at 21(1)℃. The strutures were refined to final error indices, Ri:0.057 and R2 =0.063 with 186 reflections and Rl:0.082 and R2:0.085 with 181 reflections, respectively, for which 1>3σ(In both structure, six lie at two distinguished threefold axes of unit cell ten the crystal structure of an iodine sorption complex of Cd6-A four Cd2+ ions are recessed 0.69(1) A into the large cavity to complex each with from the (111) plane of 0(3), whereas two Cd2+ ions recessed 0.68(1) A into the sodalite unit Awximately 4.0 l3ions per nit cell are sorbed. Each bridge between a Cd2+ ion and 8-ring oxygens ((I-I-I)= 117(1) ˚ and 0(1)-I(1)-I(2)=172(1)). The near linear I-I-0 angle and its interatomic distance (I-0=3.57(3) A) are indicative of a weak charge transfer interacticn between the frarrework oxygen and iodine. The existence of In3 inside the large cavity indicates that the If ions and H ions may be produced by reaction of In vapor with water molecules which maybe associated with Cd2+ ions in partially dehydrated Cd6-A In3- ions may be produced by the combination of I- and I2.

• Applied Chemistry for Engineering
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• v.33 no.6
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• pp.581-587
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• 2022

The leather industry generates a large amount of hazardous leather waste of various types every year. Among them, shaving scrap is difficult to recycle because it contains chromium ions. Many studies in recent years have shown that shaving scraps can be processed into various types of valuable products, such as adsorbent, filler, and poultry feed. In this study, collagen peptides were extracted from shaving scraps and structurally modified to be developed as new materials with improved physicochemical properties. First, the chromium ions contained in the shaving scraps were removed using a sodium hydroxide solution, and purified through concentration and low-temperature crystallization. The purified collagen peptide was used to prepare the powder using a spray dryer. The extracted collagen peptides were structurally modified by introducing double bonds by reacting with methacrylic anhydride (MAA), and the product was confirmed by ¹H NMR spectroscopy. Next, a copolymer was prepared by redox polymerization of the modified collagen peptide (MCP) and 2-ethylhexyl acrylate (2-EHA). The structure of the copolymer was qualitatively confirmed by FT-IR. In conclusion, this study confirmed that collagen peptides can be extracted from shaving scrap and converted into new eco-friendly materials through certain treatments.

• Applied Chemistry for Engineering
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• v.29 no.6
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• pp.716-725
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• 2018

In this study, antimicrobial and antioxidative activities of Perilla frutescens var. acuta were investigated with 50% ethanol and the ethyl acetate fraction and also the components were analyzed. The minimum inhibitory concentration (MIC) of the ethyl acetate fraction for both Staphylococcus aureus and Pseudomonas aeruginosa were $78{\mu}g/mL$, indicating high antimicrobial effects. The free radical scavenging activity ($FSC_{50}$) and the reactive oxygen species (ROS) scavenging activity ($OSC_{50}$) in $Fe^{3+}-EDTA/H_2O_2$ system values of the ethyl acetate fraction were $25.90{\mu}g/mL$ and $1.40{\mu}g/mL$, respectively. After the cell damage induced by $400mJ/cm^2$ UVB irradiation, the cytoprotective effect of the ethyl acetate fraction of P. frutescens var. acuta showed the concentration dependent manner ranging from 2.0 to $16.0{\mu}g/mL$. The intracellular ROS inhibitory activity in HaCaT cells decreased to 28.6% and 40.7% for the 50% ethanol extract and ethyl acetate fraction, respectively at the concentration of $32{\mu}g/mL$. Components of rosmarinic acid, luteolin, apigenin, caffeic acid and ethyl caffeate were identified in the ethyl acetate fraction. These results suggest that the extract and fraction of P. frutescens var. acuta may be applied to the field of cosmetics as a natural material that protects the skin from an external environment by having antimicrobial and antioxidative activities.

• Korean Journal of Crystallography
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• v.10 no.2
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• pp.125-129
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• 1999

X-선 회절법을 이용하여 1-(3 Carbamoyl-3,3-diphenylpropyl)-1-methylhexahydro-1H-azepinium iodide[이하: DIP]의 분자 및 결정구조를 규명하였다. 이 결정의 분자식은 C23H31N2O·I, 결정계는 Monoclinic이며 공간군은 P21이다. 단위포 상수는 a =8.937(1) Å, b=19.522(2) Å, c=6.485(2) Å이며, β= 105.18(2)°, V=1091.9(6) Å3, T=293(2)K, Z=2, Dc=1.45 Mgm-3이다. 회절반점들의 세기는 Enarf-Nonius CAD-4 diffractometer로 얻었으며 Mo Katjs(λ=0.71073 Å)을 사용하였다. 분자구조는 직접법으로 개략적인 분자모델을 설정하고, Fo>4σ(Fo)인 4112개의 독립 회절 데이터에 대하여 최소자승법으로 정밀화하여 최종 신뢰도 값 R=5.23%인 최종적인 분자모형을 구하였다.

• Applied Chemistry for Engineering
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• v.22 no.2
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• pp.178-184
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• 2011

In this study, the antibacterial, antioxidative and inhibitory effects of Allium cepa peel extracts on tyrosinase and elastase were investigated. MIC values of the ethyl acetate fraction of Allium cepa peel on especially, S. aureus among the skin resident flora (Staphylococcus aureus, S. aureus; Propionibacterium acnes, P. acnes; Pityrosporum ovale, P. ovale; Escherichia coli, E. coli) were 0.06%. The aglycone fraction showed more excellent free radical (1,1-diphenyl-2-picrylhydrazyl radical, DPPH) scavenging activity ($FSC_{50}=5.05{\mu}g/mL$). Reactive oxygen species (ROS) scavenging activities ($OSC_{50}$) of the ethyl acetate fraction and aglycone fraction in the luminol-dependent $Fe^{3+}-EDTA/H_2O_2$ system were 0.05 and $0.03{\mu}g/mL$, respectively. The cellular protective effect of the aglycone fraction on the rose-bengal sensitized photohemolysis of human erythrocytes exhibited more prominent (${\tau}_{50}$, 480 min at $25{\mu}g/mL$). The inhibitory effects ($IC_{50}$) of the ethyl acetate fraction and aglycone fraction on tyrosinase were 9.16 and $8.68{\mu}g/mL$, the inhibitory effect ($IC_{50}$) of the aglycone fraction on elastase was $14.12{\mu}g/mL$ The transepidermal water loss of the cream containing 0.1% ethyl acetate fraction was decreased from $8.3g/m^2h$ in control to $6.8g/m^2h$ in the subjects applied with cream containing the ethyl acetate fraction. These results indicate that extract/fractions of Allium cepa peel can function as antioxidant in biological systems, particularly skin exposed to UV radiation by scavenging $^1O_2$ and other ROS, and protect cellular membranes against ROS, and possibly as antiaging agents. Allium cepa peel extract could be used as a new cosmeceutical for whitening and anti-wrinkle products.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.11a
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• pp.159-160
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• 2007

• Korean Journal of Crystallography
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• v.9 no.2
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• pp.114-119
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• 1998

Imperatorin, 9-[(3-methyl-2-butenyl)oxy]-7H-furo[3,2-g][1]benzopyran-7-one의 분자 및 결정구조를 X-선 회절법으로 연구하였다. 이 결정의 분자식은 C16H14O4, 결정계는 삼사정계이고 공간군은 P이다. 단위포상수는 a=11.818(1) , b=11.906(1) , c=11.059(1) 이며, α=96.32(1)o, β=90.74(1)o, γ=64.88(1)o, V=13.993(2) 3, T=293 K, Z=4이다. 구조해석에 사용한 X-선은 CuKα선(λ=1.5418 )을 사용하였다. 구조는 직접법으로 풀었으며 최소자승법으로 정밀화하였다. 최종 신뢰도 R 값은 F0>4σ(F0)인 3951개의 독립회절데이타로 356개 파라메타에 대해 R=7.02%이다.