• Title/Summary/Keyword: out coupling

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Thermo-Degradation Kinetics of Polyethylene (폴리에틸렌의 열분해 Kinetics)

  • Cha, Wang Seog
    • Applied Chemistry for Engineering
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    • v.10 no.3
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    • pp.432-437
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    • 1999
  • Pyrolysis of polyethylene was carried out in the stainless steel reactor of internal volume of $10cm^3$. Pyrolysis reactions were performed at temperature $390{\sim}450^{\circ}C$ and the pyrolysis products were collected separately as reaction products and gas products. The molecular weight distributions(MWDs) of each product were determined by HPLC-GPC and GC analysis. Distribution balance equation for MWDs of random and specific products were proposed to account for initiation-termination and propagation-depropagation, such as hydrogen abstraction, chain cleavage, coupling of polymer and radical. A separate chain-end scission process produces low molecular weight noncondensable gases(C1 through C5) of average molecular weight 38. Activation energies of the random-chain scission and chain-end scission rate parameters, respectively, were determined to be 35, 17 kcal/mole.

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Development of an Automatic Soil Hardness Measuring System Mountable on Agricultural Tractors (트랙터 부착형 자동 토양경도 측정 시스템 개발)

  • 이현동;김기대;김찬수;김성환
    • Journal of Biosystems Engineering
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    • v.27 no.6
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    • pp.537-546
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    • 2002
  • In this study an automatic soil hardness measuring system mountable on agricultural tractors was developed to improve the accuracy of manual soil hardness testers by a constant penetrating rate, right direction of the cone-penetrometer and the isolation of vibration from the operator. This was necessary to supply similar experimental condition for performance test of new model and comparative experiment. The results of the study are summaried as follows; 1. The system consisted of a sensing part of soil hardness, a driving part of the measuring system and an attaching part between the tractor and the measuring system. 2. The allowable limit value of the system developed was set to 392N to protect from breaking the serve motor and the coupling used in this system. 3. The driving shaft penetrated into soil by 0.3m to measure soil hardness. The soil hardness was measured at the depth of 0.3m from the soil surface but the penetrating work was stopped and the driving shaft was pulled out to protect the system when the value of the soil hardness was too big on foreign substances like stones or straws. 4. Two values measured by automatic measuring system developed in this research and manual penetrometer were compared by statistics hypothesis testing method. When two people measured the soil hardness at the depth of 0.1 and 0.15m by manual cone penetrometer, there was no relationship between two values by two people but the values at the same depths by automatic measuring system developed showed similarity. The automatic system, therefore, developed in this research was proper for measuring soil hardness.

Numerical Simulation of Winter Waves and Currents in the Haeundae Coast using 2DH Model (해운대의 겨울철 파랑 및 흐름에 대한 평면 2차원 수치모델링)

  • Yoo, Jeseon;Swinkels, Cilia;Do, Kideok
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.28 no.6
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    • pp.350-360
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    • 2016
  • In order to investigate characteristics of waves and currents varying in space in the Haeundae coast in winter, numerical simulations by using a 2-D spectral wave model(SWAN) and 2-DH hydrodynamic model(Delft3D) were carried out in this study. The results of numerical simulations were validated with the field data collected at several different locations in the study area in February, 2014. From the numerical simulations, it was found that waves and currents were significantly influenced in terms of direction and magnitude by bottom topography characterized by straggling rock crops covered with sea grasses. The coupling of SWAN and Delft3D models also revealed that alongshore currents directing from the east to the west were developed in the nearshore, due to the influence of larger waves with the main incident direction from the east.

Hydrogen Storage Capacities of MOF-5 and Microporous Carbon: Effects of Pt Loading and Hybridization (MOF-5 및 마이크로다공성 카본의 수소 저장 성능: Pt 첨가 및 하이브리드화의 영향)

  • Yunatri, Rika Tri;Suh, Dong-Jin;Suh, Young-Woong
    • Journal of Hydrogen and New Energy
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    • v.19 no.5
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    • pp.377-385
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    • 2008
  • In this study, we demonstrated that, although hydrogen molecules can be adsorbed onto the adsorbent such as MOF and MC itself, the loading of noble metal such as Pt is necessary to enhance the $H_2$ storage capacity since $H_2$ molecules can be dissociatively adsorbed on Pt metal and migrated to high-surface-area adsorbent via the primary spillover. In addition, the hybrid material have been prepared coupling MOF-5 with Pt/MC through carbon bridges formed by sucrose polymerization/carbonization. That this material showed the highest $H_2$ uptake at room temperature and about 100 bar is believed to be associated with the secondary spillover effect. Thus, such a strategy is very promising in developing $H_2$ storage technology using porous adsorbents. However, further experiments should be carried out to explore the choice of bridge carbon, the hybridization method, the dispersion technique of noble metals, etc.

A Design and Manufacture of Triple Band Antenna with Line and Arc shaped Strips for WLAN/WiMAX system (직선과 원호가 결합된 WLAN/WiMAX용 삼중대역 안테나 설계 및 제작)

  • Kwon, Man-Jea;Yoon, Joong-Han
    • The Journal of the Korea institute of electronic communication sciences
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    • v.13 no.1
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    • pp.15-22
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    • 2018
  • In this paper, a microstrip-fed triple-band monopole antenna for WLAN/WiMAX applications was proposed. The proposed antenna is consist of two arc-shaped and one strip line structure, then get the three current path and then designed in order to get triple resonant characteristics. We carried out simulation about parameters. Taking account of coupling effect, Adjusted the length of the two arc-shaped and one strip line, we get the optimized parameters. The proposed antenna is fabricated on an FR-4 substrate, the dielectric constant is 4.4, and total size is $23.5mm(W1){\times}32.0mm(L1){\times}1.0mm(t)$, and its proposed antenna size is $21.0mm(W6){\times}31.0mm(L7)$. From the measured results, return loss of the proposed antenna satisfied return loss 927 MHz (1.844~2.771 GHz), 926 MHz (3.33~4.256 GHz), and 1,415 MHz (5.13~6.545 GHz). And measured results of gain and radiation patterns displayed for operating bands.

Effect of SMA on the Interfacial Shear Strength for Single Glass Fiber and PC/SAN Blends (SMA가 PC/SAN 블렌드와 유리섬유간의 계면결합력에 미치는 영향)

  • Lee, Ui-Hwan;Nam, Gi-Jun;Lee, Jae-Uk
    • Polymer(Korea)
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    • v.25 no.4
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    • pp.512-520
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    • 2001
  • One of the most important factors which affect the mechanical properties of fiber-reinforced composite materials is the interfacial shear strength (IFSS). The IFSS of glass fiber and polycarbonate (PC)/styrene-co-acrylonitrile (SAN) blend system has been measured by the single fiber fragmentation test (SFFT). SAN contents were varied up to 30 wt% and the IFSS increased with the SAN contents. Styrene-co-maleic anhydride (SMA) was used as the compatibilizer and the glass fiber was surface treated with organosilane coupling agents. Addition of small amount of SMA in PC/SAN blend improved the IFSS by chemical bonding between maleic anhydride and silanol. The optimum MA content was 0.4 wt% of total matrix contents. Also, IFSS was greatly affected by the miscibility condition of SAN/SMA blends, which depended on the copolymer composition of SAN and SMA. It was found out that, higher IFSS could be obtained when the SAN/SMA blend was in miscible pairs. In case of SAN/SMA miscible pairs, the IFSS depended on the MA content in total matrix, not on the MA content in SMA.

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Analysis of Large-Amplitude Ship Motions Using a Cartesian-Gridbased Computational Method (직교격자 기반 수치기법을 이용한 선박의 대변위 운동해석)

  • Yang, Kyung-Kyu;Nam, Bo-Woo;Lee, Jae-Hoon;Kim, Yonghwan
    • Journal of the Society of Naval Architects of Korea
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    • v.49 no.6
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    • pp.461-468
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    • 2012
  • In this study, a Cartesian-grid method based on finite volume approach is applied to simulate the ship motions in large amplitude waves. Fractional step method is applied for pressure-velocity coupling and TVD limiter is used to interpolate the cell face value for the discretization of convective term. Water, air, and solid phases are identified by using the concept of volume-fraction function for each phase. In order to capture the interface between air and water, the tangent of hyperbola for interface capturing (THINC) scheme is used with weighed line interface calculation (WLIC) method which considers multidimensional information. The volume fraction of solid body embedded in the Cartesian grid system is calculated using a level-set based algorithm, and the body boundary condition is imposed by a volume weighted formula. Numerical simulations for the two-dimensional barge type model and Wigley hull in linear waves have been carried out to validate the newly developed code. To demonstrate the applicability for highly nonlinear wave-body interactions such as green water on the deck, numerical analysis on the large-amplitude motion of S175 containership is conducted and all computational results are compared with experimental data.

Design and fabrication of the $1.3/1.55\mum$ WDM coupler with the PSG waveguide films (PSG 광도파박막을 이용한 $1.3/1.55\mum$ WDM coupler의 설계 및 제작)

  • 전영윤;김한수;이용태;이형종
    • Korean Journal of Optics and Photonics
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    • v.6 no.4
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    • pp.310-316
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    • 1995
  • We designed the $1.3/1.55\mum$ WDM directional coupler and its coupling length was calculated with the variation of the two waveguide's core separation and other variables by the Fourier transformed scalar wave equation. We deposited the PSG films for optical waveguide by low pressure chemical vapor deposition and fabricated the WDM coupler using the laser lithography and $CF_4/O_2$ reactive ion etching process. A V -groove which was made to support and fix the optical fiber is fabricated on Si substrate by chemical etching. The WDM coupler and the V-groove are connected using UV curing epoxy. We found that propagation mode of each port of WDM coupler is single mode and maximum extinction ratio between two out ports is 6 dB for $1.3.\mum$, and 12 dB for $1.55\mum$. /TEX>.

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Imaging on a Vapor Deposited Film by Photopolymerization of a Rod-Like Molecule Consisting of Two Diacetylenic Groups

  • Chang, Ji-Young;Kyung Seo;Cho, Hyun-Ju;Lee, Cheol-Ju;Lee, Changjin;Yongku Kang;Kim, Jaehyung
    • Macromolecular Research
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    • v.10 no.4
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    • pp.204-208
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    • 2002
  • A linear rod-like molecule, bis[4-(1,3-octadynyl)phenyl] terephthalate (2), consisting of two diacetylenic groups, was prepared. The unsymmetric diacetylene was prepared by the Cadiot-Chodkiewicz coupling reaction of 1-bromohexyne with 4-ethynylphenol and linked to a benzene core by an esterification reaction with terephthaloyl chloride in tetrahydrofuran. The thin film (200 nm thickness) of compound 2 was fabricated by the physical vapor deposition on a glass plate with a thermal evaporator. In the X-ray diffraction (XRD) study, the vapor deposited film on the glass plate showed peaks with d spacings of 19.4, 5.7, and 4.5 $\AA$. This XRD pattern was quite different from that observed for compound 2 isolated by recrystallization from methylene chloride/hexane. The vapor deposited film was polymerized by UV irradiation. Photopolymerization was carried out through a photomask, resulting in a patterned image, where the irradiated part became isotropic.

High-precision modeling of uplift capacity of suction caissons using a hybrid computational method

  • Alavi, Amir Hossein;Gandomi, Amir Hossein;Mousavi, Mehdi;Mollahasani, Ali
    • Geomechanics and Engineering
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    • v.2 no.4
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    • pp.253-280
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    • 2010
  • A new prediction model is derived for the uplift capacity of suction caissons using a hybrid method coupling genetic programming (GP) and simulated annealing (SA), called GP/SA. The predictor variables included in the analysis are the aspect ratio of caisson, shear strength of clayey soil, load point of application, load inclination angle, soil permeability, and loading rate. The proposed model is developed based on well established and widely dispersed experimental results gathered from the literature. To verify the applicability of the proposed model, it is employed to estimate the uplift capacity of parts of the test results that are not included in the modeling process. Traditional GP and multiple regression analyses are performed to benchmark the derived model. The external validation of the GP/SA and GP models was further verified using several statistical criteria recommended by researchers. Contributions of the parameters affecting the uplift capacity are evaluated through a sensitivity analysis. A subsequent parametric analysis is carried out and the obtained trends are confirmed with some previous studies. Based on the results, the GP/SA-based solution is effectively capable of estimating the horizontal, vertical and inclined uplift capacity of suction caissons. Furthermore, the GP/SA model provides a better prediction performance than the GP, regression and different models found in the literature. The proposed simplified formulation can reliably be employed for the pre-design of suction caissons. It may be also used as a quick check on solutions developed by more time consuming and in-depth deterministic analyses.