• Title/Summary/Keyword: 구조 최적화

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Preparation and Characterization of Silk Fibroin/Gelatin Hybrid Scaffolds (실크 피브로인/젤라틴 하이브리드 지지체의 제조 및 특성분석)

  • Kim, Hye-Lin;Hong, Min-Sung;Kim, Su-Jin;Jo, Han-Su;Yoo, Il-Sou;Lee, Dong-Won;Khang, Gil-Son
    • Polymer(Korea)
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    • v.35 no.5
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    • pp.378-384
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    • 2011
  • Silk fibroin is a biocompatible and slowly biodegradable natural polymer. This natural polymer has excellent mechanical properties, non-toxicity, and non-immunogenic properties and has been demonstrated to support tissue regeneration. Also, gelatin is a natural material derived from collagen by hydrolysis and has an almost identical composition as that of collagen. Silk fibroin/gelatin scaffolds have been fabricated by using the freeze-drying method. To establish the scaffold manufacturing condition for silk fibroin and gelatin, we made scaffolds with various compositions of gelatin, glutaldehyde and silk fibroin. The silk fibroin/gelatin scaffolds were characterized using SEM, DSC, and water absorption ability tests. The cellular proliferation was evaluated by WST assay. These results suggested that a scaffold containing 8% of gelatin, 1% of glutaldehyde and 0.3 g of silk fibroin provided suitable characterstics for cell adhesion and proliferation. In conclusion, the silk fibroin/gelatin scaffold may serve as a potential cell delivery vehicle and a structural basis for tissue engineering.

Simulation of Noise and Vibration around the Improved Turnout System (개량분기기 인근의 소음진동 시뮬레이션)

  • Eum, Ki-Young;Um, Ju-Hwan;Lee, Chin-Hyung
    • Journal of the Korea Society for Simulation
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    • v.15 no.4
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    • pp.119-128
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    • 2006
  • A turnout system which permits trains to pass from one track to another is a combination of the switch, the crossing, lead rails which are necessary to connect the switch and the crossing, two guard rails and a switch machine for operating the switch. A turnout is the sole moving part among the railway components and has complex configuration, so the safety has always been raised an issue. In Korea, it is planned to adopt the high speed tilting train, which operates at the maximum speed of 200km/h, at conventional lines by the year of 2010. However, for the application of the tilting train to conventional lines, it is prerequisite to establish a stable turnout system allowing the tilting train to pass through it without reducing speed. Therefore, the improved turnout system for the speed-up of conventional lines has been developed and the prototype of the turnout system has been constructed. In this study, simulation of noise and vibration around the improved turnout system was performed in order to predict the generation level of noise and vibration due to passing of the tilting train through the turnout system.

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Color Filter Based on a Sub-wavelength Patterned Metal Grating (광파장 이하 주기를 갖는 금속 격자형 컬러필터)

  • Lee, Hong-Shik;Yoon, Yeo-Taek;Lee, Sang-Shin;Kim, Sang-Hoon;Lee, Ki-Dong
    • Korean Journal of Optics and Photonics
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    • v.18 no.6
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    • pp.383-388
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    • 2007
  • A color filter was demonstrated incorporating a patterned metal grating in a quartz substrate. The filter is created in a metal layer perforated with a symmetric two-dimensional array of circular holes, with the pitch smaller than the wavelength of the visible light. A finite-difference time-domain simulation was performed to analyze the device by investigating the effect of structural parameters like the grating height, the period, the hole size, and the refractive index of the hole-filling material on its performance. The device performance was especially optimized by controlling the refractive index of the material comprising the holes of the grating. And two different devices were fabricated by means of the e-beam direct writing with the following design parameters: the grating height of 50 nm, the two pitches of 340 nm for the red color and 260 nm for the green color. For the prepared device with the period of 340 nm, the center wavelength was 680 nm and the peak transmission 57%. And for the other device with the pitch of 260 nm, the center wavelength was 550 nm and the peak transmission was 50%. The filling of the hole with a material whose refractive index is matched to that of the substrate has led to an increase of ${\sim}15%$ in the transmission efficiency.

Compact Design and Fabrication of 'Improved QS-MMI' Demultiplexer (Improved QS-MMI' 1.31/1.55μm 파장분리기의 최적화 설계 및 제작)

  • Kim, Nam-Kook;Kim, Jang-Kyum;Choi, Chul-Hyun;O, Beom-Hoan;Lee, Seung-Gol;Park, Se-Gun;Lee, El-Hang
    • Korean Journal of Optics and Photonics
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    • v.16 no.3
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    • pp.248-253
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    • 2005
  • We designed and fabricated a compact multi-mode interference (MMI) wavelength demultiplexer using the concept of 'Improved Quasi-State' modes. The output power and extinction ratio were improved by utilizing modal phase error which is specially occurred in low-index contrast. For a designed demultiplexer, the mode propagation analysis with effective index approximation shows significant improvement of extinction ratio to -25 dB for both $1.31{\mu}m\;and\;1.51{\mu}m$ wavelength region and the split-length was reduced about 1/5 of other MMI devices. The fabricated device shows successful characteristics for both 1.31 and $1.55{\mu}m$ wavelengths. These results demonstrate the potential of low-index materials system and the embossing process for photonic integrated circuits.

Development and Evaluation of a SYBR Green Real-time PCR Assay for Canine Cytokine Gene Expression (SYBR Green 실시간 역전사 중합효소연쇄반응을 이용한 개 싸이토카인 유전자 발현의 정량)

  • Yu, Do-Hyeon;Ihn, Dong-Chul;Park, Chul;Park, Jin-Ho
    • Journal of Veterinary Clinics
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    • v.27 no.5
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    • pp.508-513
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    • 2010
  • Cytokines are important mediators of the immune response, and quantitating cytokine mRNA is a highly sensitive and attractive method for measuring cytokine production. The objective of the current study was to develop and validate a SYBR green quantitative real-time reverse transcriptase PCR (qRT-PCR) assay for measuring canine cytokine mRNA. The optimal annealing temperatures ($T_a$) of the designed primers were $62^{\circ}C$ for interleukin (IL)-$1{\beta}$, IL-6 and IL-10; $60^{\circ}C$ for glyceraldehyde 3-phosphate dehydrogenase (GAPDH) and tumor necrosis factor (TNF)-${\alpha}$; and $58^{\circ}C$ for high mobility group box 1 (HMGB1). Primer efficiencies of all primers calculated for standard curve samples were between 97.1% and 102.6%. No evidence of secondary structure or primer-dimer formation was seen via melt-curve analysis or gel electrophoresis. The developed qRT-PCR assays are highly specific and sensitive and can be used to quantify gene expression levels of canine cytokines.

3D-QSAR Analysis on the Fungicidal Activity of N-phenyl-O-phenylthionocarbamate Analogues against Gray Mold (Botrytis cinerea) (잿빛곰팡이병균(Botrytis cinerea)에 대한 N-Phenyl-O-phenyl-thionocarbamate 유도체들의 살균활성에 관한 3D-QSAR 분석)

  • Sung, Nack-Do;Park, Kee-Han;Jang, Seok-Chan;Soung, Min-Kyu
    • The Korean Journal of Pesticide Science
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    • v.11 no.2
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    • pp.59-66
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    • 2007
  • Three dimensional quantitative structure-activity relationships (3D-QSARs) on the fungicidal activity of N-phenyl-O-phenylthionocarbamate analogues against resistant and sensitive gray mold (Botrytis cinerea) (RBC & SBC) were studied quantitatively using CoMFA and CoMSIA methods. The correlation coefficient and predict- ability of optimized CoMFA model with the atom based fit alignment were better ($r^2$ & $q^2=CoMFA{\gg}CoMSIA$) than that of CoMSIA model. And statistical values of the models on the fungicidal activity against SBC were showed higher ($r^2=SBC{\gg}RBC$) than that of RBC. In CoMFA models, steric field on the activity was more influenced than electrostatic field. And in case of CoMSIA models, the influence of CoMSIA field on the activity against RBC and SBC was differ from each other but the influence of H-bond donor field was same to the two fungi. It is revealed that the selectivity factor with CoMFA model on the fungicidal activity between the two fungi was caused on the difference of steric field. Therefore, it is predicted that the large steric field with meta- and para-substituents on the N-phenyl ring will be improved to the fungicidal activity with SBC.

Quasi-Static Equilibrium of a Propeller Shaft in a Hydrodynamic Oil-Lubricated Stern Tube Bearing (윤활유(潤滑油) 선미관(船尾管) 베어링 축계(軸系)의 준정적(準靜的) 평형상태(平衡狀態)에 관한 연구(硏究))

  • S.Y.,Ahn;S.S.,Kim
    • Bulletin of the Society of Naval Architects of Korea
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    • v.26 no.3
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    • pp.51-61
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    • 1989
  • Recently, the growth in the propulsion power and propeller size of typical energy saving ships has resulted in severe damages of the oil-lubricated stern tube bearing. Consequently, a more rational analytical method for the design of the shafting system is required. In this paper an analytical method applicable to the design of the oil-lubricated stern tube bearing and shafting system is presented. The method consists of the finite element analysis of the shafting system and the oil film hydrodynamics. The shafting system is modeled as a three-dimensional problem using beam elements taking account for the steady components of thrust, lateral forces and moments of the propeller as well as the elastic foundation effects. The oil film hydrodynamics is modeled as a two-dimensional problem. Equal and retangular elements employing hourglass control method are used for the construction of the oil film fluidity matrix. To search the quasi-static equilibrium position between the propeller shaft and the oil film, an optimization technique is employed. Some numerical results based on the proposed method are compared with some measured and numerical data available. They show acceptable agreements with the data.

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A 12b 100MS/s 1V 24mW 0.13um CMOS ADC for Low-Power Mobile Applications (저전력 모바일 응용을 위한 12비트 100MS/s 1V 24mW 0.13um CMOS A/D 변환기)

  • Park, Seung-Jae;Koo, Byeong-Woo;Lee, Seung-Hoon
    • Journal of the Institute of Electronics Engineers of Korea SD
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    • v.47 no.8
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    • pp.56-63
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    • 2010
  • This work proposes a 12b 100MS/s 0.13um CMOS pipeline ADC for battery-powered mobile video applications such as DVB-Handheld (DVB-H), DVB-Terrestrial (DVB-T), Satellite DMB (SDMB), and Terrestrial DMB (TDMB) requiring high resolution, low power, and small size at high speed. The proposed ADC employs a three-step pipeline architecture to optimize power consumption and chip area at the target resolution and sampling rate. A single shared and switched op-amp for two MDACs removes a memory effect and a switching time delay, resulting in a fast signal settling. A two-step reference selection scheme for the last-stage 6b FLASH ADC reduces power consumption and chip area by 50%. The prototype ADC in a 0.13um 1P7M CMOS technology demonstrates a measured DNL and INL within 0.40LSB and 1.79LSB, respectively. The ADC shows a maximum SNDR of 60.0dB and a maximum SFDR of 72.4dB at 100MS/s, respectively. The ADC with an active die area of 0.92 $mm^2$ consumes 24mW at 1.0V and 100MS/s. The FOM, power/($f_s{\times}2^{ENOB}$), of 0.29pJ/conv. is the lowest of ever reported 12b 100MS/s ADCs.

Total Degradation Performance Evaluation of the Time- and Frequency-Domain Clipping in OFDM Systems (OFDM 시스템에서 시간 및 주파수 영역 클리핑의 Total Degradation 성능평가)

  • Han, Chang-Sik;Seo, Man-Jung;Im, Sung-Bin
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.44 no.7 s.361
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    • pp.17-22
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    • 2007
  • OFDM (Orthogonal Frequency Division Multiplexing) is a special case of multicarrier transmission, where a single data stream is transmitted over a number of lower-rate subcarrier. One of the main reasons to use OFDM is to increase robustness against frequency-selective fading or narrowband interference. Unfortunately, an OFDM signal consists of a number of independently modulated subcarriers, which can give a large PAPR (Peak-to-Average Power Ratio) when added up coherently. In this paper, we investigate the performance of a simple PAPR reduction scheme, which requires no change of a receiver structure or no additional information transmission. The approach we employed is clipping in the time and frequency domains. The time-domain clipping is carried out with a predetermined clipping level while the frequency-domain clipping is done within EVM (Error Vector Magnitude). This approach is suboptimal with lower computational complexity compared to the optimal method. This evaluation is carried out on the OFDM system with an nonlinear amplifier. The simulation results demonstrated that the PAPR reduction algorithm is one of ways to reduce the effects of the nonlinear distortion of an HPA (High Power Amplifier).

Evaluation of Flexural Behavior of Lightweight Precast Panel with Ultra High Performance Concrete (초고성능 콘크리트를 적용한 경량 프리캐스트 패널의 휨 거동 평가)

  • Kim, Kyoung-Chul;Koh, Kyung-Taek;An, Gi-Hong;Son, Min-Su;Kim, Byung-Suk
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.8 no.3
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    • pp.269-275
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    • 2020
  • In this study, flexural tests of precast concrete panels according to the thickness of cross-sectional and the with or not of reinforcement were carried out in order to develop and assess of a lightweight precast concrete panel using ultra high performance concrete. For the test, four panels were fabricated, and consisted of one normal concrete panel and three ultra high performance concrete panels. As a test result, it was found that the plain precast panel using ultra high performance concrete had a lower flexural performance than the reinforced normal concrete panel, regardless of the cross-sectional size. The flexural performance of the hollow-sectional precast panel applying ultra high performance concrete, is improved by 150% compared to that of the reinforced normal concrete panel. That is, through additional performance verification and optimization of the cross-sectional design of the panel, the ultra high performance concrete precast panel can be made lighter. Also, the practical use of lightweight precast panels with ultra high performance concrete can be available through evaluation on shear, joint connection and anchoring, etc.