• Title/Summary/Keyword: Energy density

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Low Cycle Fatigue Life Prediction of HSLA Steel Using Total Strain Energy Density (전변형률 에너지밀도를 이용한 고강도 저 합금강의 저주기 피로수명 예측)

  • Kim, Jae-Hoon;Kim, Duck-Hoi
    • Journal of the Korean Society for Precision Engineering
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    • v.19 no.6
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    • pp.166-175
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    • 2002
  • Low cycle fatigue tests are performed on the HSLA steel that be developed for a submarine material. The relation between strain energy density and numbers of cycles to failure is examined in order to predict the low cycle fatigue life of HSLA steel. The cyclic properties are determined by a least square fit techniques. The life predicted by the strain energy method is found to coincide with experimental data and results obtained from the Coffin-Manson method. Also the cyclic behavior of HSLA steel is characterized by cyclic softening with increasing number of cycle at room temperature. Especially, low cycle fatigue characteristics and microstructural changes of HSLA steel are investigated according to changing tempering temperatures. In the case of HSLA steel, the $\varepsilon$-Cu is farmed in $550^{\circ}C$ of tempering temperature and enhances the low cycle fatigue properties.

The Effect of a CAM Treatment on the Sinterability of UO2 Powder (연속형 아트리션 밀링 처리가 UO2 분말의 소결성에 미치는 영향)

  • Moon, Je-Sun;Na, S.H.;Kang, K.H.;Park, C.S.;Song, K.C.
    • Journal of Powder Materials
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    • v.14 no.1 s.60
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    • pp.8-12
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    • 2007
  • The effect of a CAM (Continuous Attrition Mill) treatment on the sinterability of ex-ADU $UO_2$ powder was investigated. As the cycles of a CAM increased, the apparent density, specific surface area and O/U of the milled powder increased, but there particle sizes decreased. However the sintered density of the $UO_2$ pellet decreased as the cycles of the CAM increased. It is considered that the decrease of the sintered density is due to the formation of $U_3O_8$, which was produced by a CAM mechanism.

A study for prediction of temperature distribution in laser-assisted turning for rod-shaped cast iron (레이저 보조선삭 중 주철환봉 내부의 온도분포 예측에 관한 연구)

  • Kim, Kwan-Woo;Cho, Hae-Yong;Lee, Jae-Hoon;Suh, Jeong;Shin, Dong-Sig
    • Laser Solutions
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    • v.13 no.2
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    • pp.10-16
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    • 2010
  • Laser-assisted machining is dependent on absorbed energy density into workpiece. Generally, the absorptivity of laser beam is dependent on wave length of laser, materials, surface roughness, etc. Various shapes and energy densities for beam irradiation can be used to laser-assisted machining. In this thesis, efficient method of heat source modeling was developed and designed by using one fundamental experimental trials. And then, laser-assisted machining of rod-shaped cast iron was simulated by using commercial FEM code MARC. Simulations and experiments with various conditions were carried out to determine suitable condition of pre-heating for laser-assisted turning process. Temperature distribution of cutting zone could be predicted by simulation.

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Effect of Deposition Parameters on the Properties of Pyrolytic Carbon Deposited by Fluidized-Bed Chemical Vapor Deposition (유동층 화학증착법을 이용하여 증착한 열분해 탄소의 특성에 미치는 증착조건의 영향)

  • Park, Jeong-Nam;Kim, Weon-Ju;Park, Jong-Hoon;Cho, Moon-Sung;Lee, Chae-Hyun;Park, Ji-Yeon
    • Korean Journal of Materials Research
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    • v.18 no.8
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    • pp.406-410
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    • 2008
  • The properties of pyrolytic carbon (PyC) deposited from $C_2H_2$ and a mixture of $C_2H_2/C_3H_6$ on $ZrO_2$ particles in a fluidized bed reactor were studied by adjusting the deposition temperature, reactant concentration, and the total gas flow rate. The effect of the deposition parameters on the properties of PyC was investigated by analyzing the microstructure and density change. The density could be varied from $1.0\;g/cm^3$ to $2.2\;g/cm^3$ by controlling the deposition parameters. The density decreased and the deposition rate increased as the deposition temperature and reactant concentration increased. The PyC density was largely dependent on the deposition rate irrespective of the type of the reactant gas used.

INDUCTION PLASMA DEPOSITION TECHNOLOGY FOR NUCLEAR FUEL FABRICATION

  • I. H. Jung;K. K. Bae;Lee, J. W.;Kim, T. K.;M. S. Yang
    • Proceedings of the Korean Nuclear Society Conference
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    • 1998.05b
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    • pp.216-221
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    • 1998
  • A study on induction plasma deposition with ceramic materials, yttria-stabilized-zirconia ZrO$_2$-Y$_2$O$_3$ (m.p 264O $^{\circ}C$), was conducted with a view developing a new method for nuclear fuel fabrication Before making dense pellets more than 96%TD., the spraying condition was optimized through the process parameters, such as chamber pressure, plasma plate power powder spraying distance, sheath gas composition, probe position, particle size and powders different morphology. The results with a 5mm thick deposit on rectangular planar graphite substrates showed a 97.11% theoretical density when the sheath gas flow rate was Ar/H$_2$120/20 l/min, probe position 8cm, particle size -75 ${\mu}{\textrm}{m}$ and spraying distance 22cm by AMDRY146 powder. The degree of influence of the main effects on density were powder morphology. particle size, sheath gas composition, plate power and spraying distance, in that order. Among the two parameter interactions, the sheath gas composition and chamber pressure affects density greatly. By using the multi-pellets mold wheel type, the pellet density did not exceed 94%T.D., owing to the spraying angle.

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Initial Reaction of Hexachlorodisilane on Amorphous Silica Surface for Atomic Layer Deposition Using Density Functional Theory

  • Kim, Ki-Young;Yang, Jin-Hoon;Shin, Dong-Gung;Kim, Yeong-Cheol
    • Journal of the Korean Ceramic Society
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    • v.54 no.5
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    • pp.443-447
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    • 2017
  • The initial reaction of hexachlorodisilane ($Si_2Cl_6$, HCDS) on amorphous silica ($SiO_2$) surface for atomic layer deposition was investigated using density functional theory. Two representative reaction sites on the amorphous $SiO_2$ surface for HCDS reaction, a surface hydroxyl and a two-membered ring, were considered. The reaction energy barrier for HCDS on both sites was higher than its adsorption energy, indicating that it would desorb from the surface rather than react with the surface. At high temperature range, some HCDSs can have kinetic energy high enough to overcome the reaction energy barrier. The HCDS reaction on top of the reacted HCDS was investigated to confirm its self-limiting characteristics.

Effect of Seawater/Fresh Water Flow Rates on Power Density of Reverse Electrodialysis (RED 전력밀도에 미치는 해수/담수 유량의 영향)

  • Na, Jong-Chan;Kim, Han-Ki;Kim, Chan-Soo;Han, Moon-Hee
    • Journal of Korean Society of Environmental Engineers
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    • v.36 no.9
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    • pp.624-628
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    • 2014
  • Reverse electrodialysis (RED) is a technique to produce electricity from two feed water that has different salinity. Recently, RED has been considered the attractive technology because this new process has large global potential and possibility to generate energy from abundant but largely unused resources. To make RED an economically attractive technology, the optimization of operation condition should be developed. In this study, we investigate the relation of internal resistance to power density of RED. And the effect of sea water and fresh water flow rate on power density was confirmed. To minimize the internal resistance and to increase power density of RED, the ratio of sea water and fresh water flow rate was optimized. Experimental result show the best performance with $1.30W/m^2$ of power density at 1.7 flow ratio of seawater/freshwater.

Electricity Generation Using Cyanobacteria Synechocystis PCC 6803 in Photosynthetic Bio-Electrochemical Fuel Cell (남조류 Synechocystis PCC 6803을 이용한 생물전기화학적 물분해 전기 생산)

  • Kim, Min-Jin;Oh, You-Kwan;Kim, Mi-Sun
    • Transactions of the Korean hydrogen and new energy society
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    • v.19 no.6
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    • pp.529-536
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    • 2008
  • Cyanobacteria Synechocystis PCC 6803 or the extracted thylakoid membrane from this strain was appled to photosynthetic bio-electrochemical fuel cell(PBEFC) for the production of hydrogen under the illumination of 48Klux using halogen lamp. PBEFC was composed of anode, cathode and membrane between them. Electrode material was carbon paper while electron mediator and receptor were added phenazine methosulfate(PMS) and potassium ferricyanide respectively. When water and 50 mM tricine buffer and $300{\mu}M$ PMS were added to the anode under the light condition, PBEFC produced the current density $4.4{\times}10^{-5}\;mA/cm^2$, $1.4{\times}10^{-4}\;mA/cm^2$ and $2.4{\times}10^{-4}\;mA/cm^2$, respectively. And the addition of the thylakoid membrane to the system increased current density to $1.3{\times}10^{-3}\;mA/cm^2$. Two times increase of the thylakoid membrane into the anode doubled the current density to $2.6{\times}10^{-3}\;mA/cm^2$. But the current density was not increased proportionally to the amount of thylakoid membrane increased. The system was unstable to measure the electricity output due to the foam production in the anode. Addition of triton X-100 and tween 80 stabilized the system to measure the electricity output but the current density was not increased higher than $8.4{\times}10^{-4}\;mA/cm^2$ and $2.3{\times}10^{-3}\;mA/cm^2$. When the thylakoid membrane was substituted to Synechocystis PCC 6803 cells of four-day culture which has chlorophyll contents $20.5{\mu}g/m{\ell}$, maximum current density was $1.3{\times}10^{-3}\;mA/cm^2$ with $1\;k{\Omega}$ resistance.

Effect of Total Collimation Width on Relative Electron Density, Effective Atomic Number, and Stopping Power Ratio Acquired by Dual-Layer Dual-Energy Computed Tomography

  • Jung, Seongmoon;Kim, Bitbyeol;Yoon, Euntaek;Kim, Jung-in;Park, Jong Min;Choi, Chang Heon
    • Progress in Medical Physics
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    • v.32 no.4
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    • pp.165-171
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    • 2021
  • Purpose: This study aimed to evaluate the effect of collimator width on effective atomic number (EAN), relative electron density (RED), and stopping power ratio (SPR) measured by dual-layer dual-energy computed tomography (DL-DECT). Methods: CIRS electron density calibration phantoms with two different arrangements of material plugs were scanned by DL-DECT with two different collimator widths. The first phantom included two dense bone plugs, while the second excluded dense bone plugs. The collimator widths selected were 64 mm×0.625 mm for wider collimators and 16 mm×0.625 mm for narrow collimators. The scanning parameters were 120 kVp, 0.33 second gantry rotation, 3 mm slice thickness, B reconstruction filter, and spectral level 4. An image analysis portal system provided by a computed tomography (CT) manufacturer was used to derive the EAN and RED of the phantoms from the combination of low energy and high energy CT images. The EAN and RED were compared between the images scanned using the two different collimation widths. Results: The CT images with the wider collimation width generated more severe artifacts, particularly with high-density material (i.e., dense bone). RED and EAN for tissues (excluding lung and bones) with the wider collimation width showed significant relative differences compared to the theoretical value (4.5% for RED and 20.6% for EAN), while those with the narrow collimation width were closer to the theoretical value of each material (2.2% for EAN and 2.3% for RED). Scanning with narrow collimation width increased the accuracy of SPR estimation even with high-density bone plugs in the phantom. Conclusions: The effect of CT collimation width on EAN, RED, and SPR measured by DL-DECT was evaluated. In order to improve the accuracy of the measured EAN, RED, and SPR by DL-DECT, CT scanning should be performed using narrow collimation widths.

Evaluation for Mechanical Properties of Compress Strength and Dry Density of Concrete at NPP (원전 시설용 콘크리트의 압축강도 및 건조밀도 특성 평가)

  • Lee, Young-Dae;Kim, Gyu-Yong;Shin, Kyoung-Su;Nam, Jeong-Soo;Lee, Tae-Gyu;Choe, Gyeong-Choel
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2011.11a
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    • pp.53-54
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    • 2011
  • The facilities producing the nuclear energy chosen for resolving the recent global energy problem have been increasingly constructed, and hence more frequent durability tests on radiation shielding concrete are required due to NPP(Nuclear Power Plant) life extension and increase of radioactive waste repositories. Bulk dry density is one of the critical factors ensuring the durability and performance of the radiation shielding concrete because the design of the radiation shielding reinforced concrete structures for NPPs is based on the bulk dry density of the concrete. Bulk density of unconsolidated shielding concrete can be calculated utilizing a test assuring to satisfy the bulk dry density, or existing credible data set. This study evaluated correlation between bulk density and bulk dry density of the concrete used for Korean NPPs (y=1.0913X-0.2458) and developed a correlation expression considering standard deviation of bulk dry density (y=1.0913X-0.3358).

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