• Title/Summary/Keyword: 강도 최적화

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Mechanical Property Improvement of the H13 Tool Steel Sculptures Built by Metal 3D Printing Process via Optimum Conditions (금속 3D 프린팅 공정 최적화를 통한 H13 공구강 조형체의 기계적 특성 향상)

  • Yun, Jaecheol;Choe, Jungho;Lee, Haengna;Kim, Ki-Bong;Yang, Sangsun;Yang, Dong-Yeol;Kim, Yong-Jin;Lee, Chang-Woo;Yu, Ji-Hun
    • Journal of Powder Materials
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    • v.24 no.3
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    • pp.195-201
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    • 2017
  • In this study, H13 tool steel sculptures are built by a metal 3D printing process at various laser scan speeds. The properties of commercial H13 tool steel powders are confirmed for the metal 3D printing process used: powder bed fusion (PBF), which is a selective laser melting (SLM) process. Commercial H13 powder has an excellent flowability of 16.68 s/50 g with a Hausner ratio of 1.25 and a density of $7.68g/cm^3$. The sculptures are built with dimensions of $10{\times}10{\times}10mm^3$ in size using commercial H13 tool steel powder. The density measured by the Archimedes method is $7.64g/cm^3$, similar to the powder density of $7.68g/cm^3$. The hardness is measured by Rockwell hardness equipment 5 times to obtain a mean value of 54.28 HRC. The optimum process conditions in order to build the sculptures are a laser power of 90 W, a layer thickness of $25{\mu}m$, an overlap of 30%, and a laser scan speed of 200 mm/s.

Transient Structural Analysis of Piston and Connecting Rods of Reciprocating Air Compressor Using FEM (FEM을 이용한 왕복동 공기압축기의 피스톤 및 커넥팅로드의 구조해석)

  • Pham, Minh-Ngoc;Yang, Chang-Jo;Kim, Jun-Ho;Kim, Bu-Gi
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.23 no.4
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    • pp.393-399
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    • 2017
  • In a reciprocating compressor, the piston and connecting rod are important parts. Excess mechanical stress on these parts may cause damage, and broken parts are expensive and difficult to replace. Therefore, it is necessary to analyze the mechanical stress affecting durability and longevity. The main purpose of this study was to identify locations of maximum stress on pistons and connecting rods. Based on dynamic calculation of the working process of a specific air compressor, an analysis of piston and connecting rod performance has been completed. A three-dimensional model for the air compressor's pistons and connecting rods was built separately, and FEM analysis of these components was carried out using a numerical method. The pistons were loaded by pressure which was changed according to crankshaft angle without thermal boundary conditions. The simulation results were used to predict and estimate stress concentration as well as the value of this stress on pistons and connecting rods. The maximum equivalent stress calculated are over 190 MPa on pistons and 123 MPa on connecting rods at crank angle $135^{\circ}$ and $225^{\circ}$ but these are under tensile yield strength. Besides, the calculated safety factors of connecting rods and pistons is higher than 1. Moreover, the results obtained can be used to provide manufacturers with references to optimize the design of pistons and connecting rods for reciprocating compressors.

Cloning and Expression of Indole Oxygenase Gene Derived from Rhodococcus sp. RHA1 (Rhodococcus sp. RHA1 유래의 Indole Oxygenase의 클로닝 및 발현)

  • Kang, Mi-Suk;Lee, Jin-Ho
    • Microbiology and Biotechnology Letters
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    • v.37 no.3
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    • pp.197-203
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    • 2009
  • An indole oxygenase originated from Rhodococcus sp. RHA1 was cloned into the expression vector, pTrc99A, in Escherichia coli, and designated pTCAN1. The pTCAN2 was constructed from pTCAN1 by the deletion of $lacI^q$ for the constitutive expression of indole oxygenase without adding IPTG in the medium. The complete open reading frame of indole oxygenase was 1,224 bp long, which encodes a protein of 407amino acids. Crude extracts of E. coli $DH5{\alpha}$/pTCAN1 and pTCAN2, respectively, were prepared and subjected to SDS-PAGE analysis. A band corresponding to molecular mass of about 43 kDa was appeared and this result correlated with the predicted molecular mass of cloned indole oxygenase. The E. coli harboring pTCAN1 and pTCAN2, respectively, showed blue color colony in LB plate. The pigment showing blue color was prepared from E. coli $DH5{\alpha}$/pTCAN2, and identified as indigo by experiments using spectrophotometer, HPLC, and TLC. The indigo-forming activity of indole oxygenases from the whole cell of E. coli $DH5{\alpha}/pTCAN1$ cultured at LB medium added 1mM of IPTG and that of E. coli/pTCAN2 showed about 1.75nmol/min/mg DCW (dry cell weight) and 3.85 nmol/min/mg DCW, respectively. Also, the E. coli $DH5{\alpha}$/pTCAN2 produced about $236{\mu}M$ of indigo after 48 hours incubation in TB medium supplemented with 2.5 mM of tryptophan.

Development of Reliability-Based Optimum Design of High-Speed Railway Bridges Considering Structure-Rail Longitudinal Interaction and Structure-Vehicle Interaction Using Heuristic Decision Method (Heuristic Decision Method를 이용하여 구조물-궤도 종방향 상호작용 및 구조물-차량 상호작용을 고려한 고속철도 교량의 신뢰성 최적설계 기법 개발)

  • Ihm, Yeong-Rok
    • Journal of the Korean Society of Hazard Mitigation
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    • v.10 no.3
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    • pp.31-38
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    • 2010
  • In this study, it is suggested that it has to reliability-based design methodology with respect to bridge structure-rail longitudinal interaction and bridge structure-vehicle interaction. For the structural analysis, commercial package, ABAQUS, are used for a three-dimensional finite element analysis. The optimization process utilizes a well-known optimizer, ADS(Automated Design Synthesis). Optimization technique is utilized the ALM-BFGS method for global area search and Golden Section Method for 1-D search. In general, ALM-BFGS method don't need the 1-D search, and that algorithm converge a 0.1~0.2 of Push-Off factor. But in this study, value of Push-Off factor is used 90, therefore 1-D search should be needed for effective convergency. That algorithm contains the "heuristic decision method". As a result of optimum design of 2-main steel girder birdge with 5${\times}$(1@50m), design methodology suggested in this study was demonstrated more economic and efficient than existing design and LCC optimization not considering bridge-rail longitudinal interaction and bridge-vehicle interaction.

Processing Optimization of Seasoned Laver Pyropia yezoensis Using Seasoning Sauce with Conger Eel Conger myriaster (붕장어(Conger myriaster) 시즈닝을 활용한 조미김(Pyropia yezoensis)의 제조공정 최적화)

  • Kim, Do Youb;Kang, Sang In;Lee, Chang Young;Kim, Hye Jin;Lee, Jung Suck;Heu, Min Soo;Kim, Jin-Soo
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.53 no.3
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    • pp.368-381
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    • 2020
  • This study was conducted to optimize the processing conditions of seasoned laver Pyropia yezoensis with conger eel Conger myriaster seasoning sauce (CES) using response surface methodology (RSM). The RSM program results for bonesoftness showed that the optimum independent variables based on the dependent variables (Y1, lipid removal rate; Y2, texture; and Y3, sensory fish odor score) were 431.0% for X1 (water amount), 115.6℃ for X2 (retort-operated temperature), and 50.1 min for X3 (retort-operated time). The RSM program results for the CES blend showed that the optimum independent variables (X1, amount of bone-softened conger eel by-products; X2, mixed sauce amount; and X3, starch amount) based on the dependent variables (Y1, amino-N; Y2, Hunter redness; and Y3, drying time) were 44.8% for A (pre-treated conger eel by-product), 36.0% for B (mixed sauce), and 19.2% for C (starch). The RSM program results for seasoned laver with CES showed that the optimum independent variables based on the dependent variables (Y1, water activity; Y2, Hunter yellowness; and Y3, overall acceptance) were 5.0% for X1, (CES amount), 313.8℃ for X2 (roasting temperature), and 6.0 s for X3 (roasting time). The seasoned laver with CES prepared under the optimum conditions was superior to commercial seasoned laver in terms of overall acceptance.

Optimization of the Processing of Seasoning Sauce for Seasoned Broughton's Ribbed Ark Scapharca broughtonii Products Using Response Surface Methodology (반응표면분석법을 활용한 피조개(Scapharca broughtonii) 조미가공품용 조미 소스의 공정 최적화)

  • Kang, Sang In;Sohn, Suk Kyung;Choi, Kwan Su;Kim, Kang-Ho;Kim, Youn Sik;Lee, Jung Suck;Heu, Min Soo;Kim, Jin-Soo
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.53 no.3
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    • pp.334-341
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    • 2020
  • This study was conducted to optimize the processing conditions of seasoned broughton's ribbed ark Scapharca broughtonii products (S-BRA-P) using response surface methodology (RSM). The concentrated oyster extract content (X1, w/w), amino-based seasoning powder content (X2, w/w), and enzyme-treated stevia content (X3, w/w) were selected as independent variables, and amino nitrogen (Y1) and overall acceptance in a sensory evaluation (Y2) were selected as dependent variables. The optimal conditions of X1, X2, and X3 were 97.5%, 20.0%, and 0.9%, respectively, and the predicted values of the multiple response optimal conditions were Y1 (1,030 mg/100 g) and Y2 (8.3). Under the optimum conditions, the experimental values of Y1 and Y2 were 1,034 ± 6.0 mg/100 g and 8.5 ± 0.4, respectively, which was no significant difference from the predicted values (P<0.05). In conclusion, the optimized models of X1, X2, and X3 for the preparation of soy sauce-based sauce were suitably fitted. The optimum amount of seasoning sauce was 13% for the preparation of S-BRA-P. The S-BRA-P, which was prepared by adding the seasoning sauce and the other subsidiary material [finely chopped spring onion (3.8%) and cheongyang hot pepper (4.6%)], had a superior taste, color, and odor.

Analysis of Hydraulic Characteristics Upstream of Dam and in Spillway Using Numerical Models (수치모형을 이용한 댐 상류 및 여수로 수리현상 해석)

  • Kim, Young-Han;Oh, Jung-Sun;Seo, Il-Won
    • Journal of Korea Water Resources Association
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    • v.36 no.5
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    • pp.761-776
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    • 2003
  • Numerical models were employed to investigate the hydrodynamics of water flow in the lake behind a dam and the spillway where supercritical flows and negative pressures are likely to occur. In this study, 2-D model, RMA2 was employed to examine the upstream flow pattern and 3-D CFD model, FLUENT was used to evaluate the three-dimensional flow in the approaching region and flow distributions in the spillways and discharge culverts. The bathymetry and the details of structures were carefully taken into consideration in building the models. The results from applying the 2-D model for the planned Hantan River Dam show that large eddies, the velocity of which reaches up to 1 m/s are occurring in several places upstream of the dam. That means that the 2-D numerical model could be utilized to investigate the two-dimensional flow patterns after the construction of a dam. Three-dimensional numerical results show that the approach flow varies depending on stages and discharge conditions, and velocities at spillways, discharge culverts, and sediment flushing tunnels are differently distributed. The velocity distributions obtained from the numerical model and a hydraulic model at the centerline of spillways 100 m upstream of the dam show reasonably similar results. It is expected that 2-D and 3-D numerical models ate useful tools to help optimize the dam design through investigating the flow patterns in the spillway and at the upstream of the dam, which is not always feasible in hydraulic modeling.

An Experimental Study for Electro-active Polymer Electrode and Actuator (전기활성 고분자 전극 및 구동기에 관한 실험적 연구)

  • Lee, Jun-Man;Ryu, Sang-Ryeoul;Lee, Dong-Joo;Lin, Zheng-Jie
    • Composites Research
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    • v.26 no.5
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    • pp.289-294
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    • 2013
  • A thinner is used to improve the multi-walled carbon nano-tube (CNT) and carbon black (CB) dispersion in a polymer matrix and to make a soft electrode. The electrical and mechanical properties of the soft electrodes are investigated as functions of CNT, CB and thinner content. The optimal mixing condition for the electrode is thinner 80, CNT 3.5, CB 18 (phr) on the basis of matrix (KE-12). The specific resistance of that is 73 (${\Omega}{\cdot}cm$), and tensile strength, tensile modulus, and elongation of that is 0.45 MPa, 0.21 MPa, and 184%, respectively. Also, a simple structure of the actuator with an optimized electrode and elastomer is fabricated and its characteristic is evaluated. At the operating voltage 25 kV, the displacement of an elastomer KE-12 is 2.24 mm, and that of an elastomer KE-12 with thinner 50 (phr) is 4.05 mm. It shows a higher displacement compared to that of 3M 4910 which has similar modulus. The actuator made with elastomer and electrode of the same material (KE-12) may have advantages for fatigue life and application.

Optimization of Medium Components for Cell Mass Production of Saccharomyces cerevisiae JUL3 using Response Surface Methodology (반응표면분석법을 이용하여 Sacharomyces cerevisaeJUL3의 균체량 생산을 위한 배지조성 최적화)

  • Kim, Young-Hwan;Kang, Seong-Woo;Lee, Jong-Ho;Chang, Hyo-Ihl;Yun, Cheol-Won;Paik, Hyun-Dong;Kang, Chang-Won;Kim, Seung-Wook
    • KSBB Journal
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    • v.21 no.6 s.101
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    • pp.479-483
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    • 2006
  • [ ${\beta}-Glucan$ ], one of the cell wall components, is most plentiful polysaccharides in cell wall and has several advantages in immune system. In yeast ${\beta}-glucan$ is mainly contained in the yeast cell wall, and thus it is important to produce high levels of cell mass for the mass production of yeast ${\beta}-glucan$. The best carbon and nitrogen sources on cell mass production were high fructose syrup and yeast extract. Response surface methodology (RSM) was very potential tool for the optimization of process factor and medium component. It was applied to estimate the effects of medium components on the production of cell mass. Optimal concentrations of high fructose syrup and yeast extract by response surface methodology were 8.0% (v/v) and 5.2% (w/v), respectively and the cell mass predicted was $17.0\;g/{\ell}$ at 20 h of cultivation.

Spatio-temporal Mode Selection Methods of Fast H.264 Using Multiple Reference Frames (다중 참조 영상을 이용한 고속 H.264의 움직임 예측 모드 선택 기법)

  • Kwon, Jae-Hyun;Kang, Min-Jung;Ryu, Chul
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.33 no.3C
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    • pp.247-254
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    • 2008
  • H.264 provides a good coding efficiency compared with existing video coding standards, H.263, MPEG-4, based on the use of multiple reference frame for variable block size motion estimation, quarter-pixel motion estimation and compensation, $4{\times}4$ integer DCT, rate-distortion optimization, and etc. However, many modules used to increase its performance also require H.264 to have increased complexity so that fast algorithms are to be implemented as practical approach. In this paper, among many approaches, fast mode decision algorithm by skipping variable block size motion estimation and spatial-predictive coding, which occupies most encoder complexity, is proposed. This approach takes advantages of temporal and spatial properties of fast mode selection techniques. Experimental results demonstrate that the proposed approach can save encoding time up to 65% compared with the H.264 standard while maintaining the visual perspectives.