• Title/Summary/Keyword: residual condition

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Volatile compounds and some physico-chemical properties of pastırma produced with different nitrate levels

  • Akkose, Ahmet;Unal, Nazen;Yalinkilic, Baris;Kaban, Guzin;Kaya, Mukerrem
    • Asian-Australasian Journal of Animal Sciences
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    • v.30 no.8
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    • pp.1168-1174
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    • 2017
  • Objective: The aim of the study was to evaluate the effects of different nitrate levels (150, 300, 450, and 600 ppm $KNO_3$) on the volatile compounds and some other properties of pastırma. Methods: Pastırma samples were produced under the controlled condition and analyses of volatile compounds, and thiobarbituric acid reactive substances (TBARS) as an indicator of lipid oxidation, non-protein nitrogenous matter content as an indicator of proteolysis, color and residual nitrite were carried out on the final product. The profile of volatile compounds of pastırma samples was analyzed by gas chromatography/mass spectrometry using a solid phase microextraction. Results: Nitrate level had a significant effect on pH value (p<0.05) and a very significant effect on TBARS value (p<0.01). No significant differences were determined in terms of $a_w$ value, non-protein nitrogenous substance content, color and residual nitrite between pastırma groups produced by using different nitrate levels. Nitrate level had a significant (p<0.05) or a very significant (p<0.01) effect on some volatile compounds. It was determined that the amounts and counts of volatile compounds were lower in the 450 and especially 600 ppm nitrate levels than 150 and 300 ppm nitrate levels (p<0.05). While the use of 600 ppm nitrate did not cause an increase in residual nitrite levels, the use of 150 ppm nitrate did not negatively affect the color of pastırma. However, the levels of volatile compounds decreased with an increasing level of nitrate. Conclusion: The use of 600 ppm nitrate is not a risk in terms of residual nitrite in pastırma produced under controlled condition, however, this level is not suitable due to decrease in the amount of volatile compounds.

Structural defects in the multicrystalline silicon ingot grown with the seed at the bottom of crucible (종자결정을 활용한 다결정 규소 잉곳 내의 구조적 결함 규명)

  • Lee, A-Young;Kim, Young-Kwan
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.24 no.5
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    • pp.190-195
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    • 2014
  • Because of the temperature gradient occurring during the growth of the ingot with directional solidification method, defects are generated and the residual stress is produced in the ingot. Changing the growth and cooling rate during the crystal growth process will be helpful for us to understand the defects and residual stress generation. The defects and residual stress can affect the properties of wafer. Generally, it was found that the size of grains and twin boundaries are smaller at the top area than at the bottom of the ingot regardless of growth and cooling condition. In addition to that, in the top area of silicon ingot, higher density of dislocation is observed to be present than in the bottom area of the silicon ingot. This observation implies that higher stress is imposed to the top area due to the faster cooling of silicon ingot after solidification process. In the ingot with slower growth rate, dislocation density was reduced and the TTV (Total Thickness Variation), saw mark, warp, and bow of wafer became lower. Therefore, optimum growth condition will help us to obtain high quality silicon ingot with low defect density and low residual stress.

Development of a New Simplified Algorithm for Residual Longitudinal Strength Prediction of Asymmetrically Damaged Ships (비대칭 손상 선박의 잔류 종강도 평가를 위한 간이 해석 알고리즘 개발)

  • Choung, Joon-Mo;Nam, Ji-Myung;Lee, Min-Seong;Jeon, Sang-Ik;Ha, Tae-Bum
    • Journal of the Society of Naval Architects of Korea
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    • v.48 no.3
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    • pp.281-287
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    • 2011
  • This paper explains the basic theory and a new development of for the residual strength prediction program of the asymmetrically damaged ships, being capable of searching moment-curvature relations considering neutral axis mobility. It is noted that moment plane and neutral axis plane should be separately defined for asymmetric sections. The validity of the new program is verified by comparing moment-curvature curves of 1/3 scaled frigate model where the results from new algorithm well coincide with experimental and nonlinear FEA results for intact condition and with nonlinear FEA results for damaged condition. Applicability of new algorithm is also verified by applying VLCC model to the newly developed program. It is proved that reduction of residual strengths is visually presented using the new algorithm when damage specifications of ABS, DNV and IMO are applied. It is concluded that the new algorithm shows very good performance to produce moment-curvature relations with neutral axis mobility on the asymmetrically damaged ships. It is expected that the new program based on the developed algorithm can largely reduce design period of FE modeling and increase user conveniences.

A Development of ZnO Varistor for Railroad Vehicle d.c. Arrester (전철탑재형 직류피뢰기용 ZnO 바리스터의 개발)

  • Cho, I-Gon;Park, Choon-Hyun;Jung, Se-Young;Song, Tae-Kwon;Kim, Suk-Soo
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2002.11a
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    • pp.552-556
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    • 2002
  • The microstructure and electrical characteristics of A~C's ZnO varistors fabricated according to variable sintering condition, which sintering temperature is $1130^{\circ}C$ and speeds of pusher are A: 2mm/min, B: 4mm/min, C: 6mm/min, respectively, were investigated. In the microstructure, A~C's ZnO varist-ors fabricated variable sintering condition was consisted of ZnO grain(ZnO), spinel phase$(Zn_{2.33}Sb_{0.67}O_4)$ Bi-rich $phase(Bi_{2}O_{3})$, wholly. Varistor voltage of A~C's ZnO varistors sintered at $1130^{\circ}C$ increased in order A < B < C's ZnO varistors. C's ZnO varistor exhibited good characteristics that nonlinear exponent is 31.70. Leakage current of A~C's ZnO varistors exhibited below 2mA at rated voltage. Lightning impulse residual voltage of A's ZnO varistor suited standard characteristics, which is 3.85kV at 2.5kA, 4.4kV at 5kA and 5.16kV at 10kA. After multi lightning impulse residual voltage test of A's ZnO varistor exhibited good discharge characteristics which ZnO varistor reveals no evidence of puncture, flashover, cracking in visual examination. After high current impulse test of A's ZnO varistor exhibited good discharge characteristics, which variation rate of residual voltage is 0.4% before and after test, and revealed no evidence.

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Residual Deformation Analysis of Composite by 3-D Viscoelastic Model Considering Mold Effect (3-D 점탄성 모델을 이용한 복합재 성형후 잔류변형해석 및 몰드 효과 연구)

  • Lee, Hong-Jun;Kim, Wie-Dae
    • Composites Research
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    • v.34 no.6
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    • pp.426-433
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    • 2021
  • The carbon fiber reinforced plastic manufacturing process has a problem in that a dimensional error occurs due to thermal deformation such as residual stress, spring-in, and warpage. The main causes of thermal deformation are various, including the shape of the product, the chemical shrinkage, thermal expansion of the resin, and the mold effect according to the material and surface condition of the mold. In this study, a viscoelastic model was applied to the plate model to predict the thermal deformation. The effects of chemical shrinkage and thermal expansion of the resin, which are the main causes of thermal deformation, were analyzed, and the analysis technique of the 3-D viscoelastic model with and without mold was also studied. Then, the L-shaped mold effect was analyzed using the verified 3D viscoelastic model analysis technique. The results show that different residual deformation occurs depending on the surface condition even when the same mold is used.

Evaluation for Weld Residual Stress and Operating Stress around Weld Region of the CRDM Nozzle in Reactor Vessel Upper Head (원자로 압력용기 상부헤드 CRDM 노즐 용접부의 용접잔류응력 및 운전응력 평가)

  • Lee, Kyoung-Soo;Lee, Sung-Ho;Bae, Hong-Yeol
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.36 no.10
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    • pp.1235-1239
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    • 2012
  • Primary water stress corrosion cracking (PWSCC) has been observed around the weld region of control rod drive mechanism (CRDM) nozzles in nuclear power plants overseas. The weld has a J-shaped groove and it connects the CRDM nozzle with the reactor vessel upper head (RVUH). It is a dissimilar metal weld (DMW), because the CRDM is made of alloy 600 and the RVUH is made of carbon steel. In this study, finite element analysis (FEA) was performed to estimate the stress condition around the weld region. Generally, it is known that a high tensile region is more susceptible to PWSCC. FEA was performed as for the condition of welding, hydrostatic test and normal operation successively to observe how the residual stress changes due to plant condition. The FEA results show that a high tensile stress region is formed around the weld starting point on the inner surface and around the weld stop point on the outer surface.

Mechanical Properties of Intermetallic/Metal Laminated Composite by SHS Reaction (자전고온반응에 의한 금속간화합물/금속 적층복합재료의 기계적 특성)

  • ;;Manabu Enoki
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2002.10a
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    • pp.60-63
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    • 2002
  • Metal/intermetallic laminated composites have been manufactured by SHS reactions between Ni and Al elemental metal foils. Microstructure showed that the intermetallic volume fraction was 55%, 45%, 35% in the 1:1, 2:1, 4:1 thickness ratio(Ni:Al) specimen and the main phases of the intermetallic were transformed from $Ni_2Al_3$ to NiAl when the thickness ratio was increased. Tensile strength and elongation were increased when the volume fraction of Ni metallic phase was increased. Under assumptions of isostrain condition, the tensile strength of metal/intermetallic laminated composites didn't obey the ROM due to the thermal residual stress and this was confirmed by X-ray residual stress analysis. Fracture toughness results by the SENB test showed R-curves with upward curvature based on LSB condition. Bridging stress based on LSB condition was determined by the curve fitting analysis, In-situ observed microstructure during fracture test showed that the various bridging mechanism such as crack bridging, crack branching and ductile failure of metallic layer were occurred

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Preservation of Takju by Pasteurization (저온살균법에 의한 탁주의 보존성 증진)

  • 배상면;김헌진;고영희;오태광
    • Microbiology and Biotechnology Letters
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    • v.18 no.3
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    • pp.322-325
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    • 1990
  • During transportation and preservation of Takju, alcohol fermentation has continued to produce $C0_2$ from residual sugar and frequently spoiled owing to bacterial contaminants wich produce organic acids. The authors could preserve Takju for more than 50 days at room temperature by pasteurization without any changes of quality. For the optimal condition of pasteurization, fresh Takju was heated at various temperatures and times. D-Value of the Saccharomyces sp. which isolated from Takju collected at seoul area was 19 see at $55^{\circ}C$. Non-spore forming bacterial contaminants, most of which known to cause acid-spoilage, were decreased when heated at $55^{\circ}C$ for 5 min. The optimal pasteurization condition of Takju was at $55^{\circ}C$ for 10 min. Spore forming bacterial contaminants, considered to be EuciiLw sp., were not sterilized after pasteurized at the optimal condition. However, the spore-forming bacteria could not increase any more and also not cause increment of acidity during preservation even at room temperature for 50 days. Reducing sugar was increased during storage of Takju after pasteurization. This suggests that the residual glucoamylase in Takju is still active after pasteurizsation and keep sweet taste.

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Heat Treatment for Improvement of Hardness Uniformity of Standard Hardness Blocks (경도 기준편의 경도 균일성 향상을 위한 열처리)

  • Hahn, J.H.;Hwang, N.M.;Kim, J.J.;Moon, H.G.
    • Journal of the Korean Society for Heat Treatment
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    • v.2 no.2
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    • pp.33-37
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    • 1989
  • In order to improve hardness uniformity of standard-hardness blocks. experimental procedure was designed using Taguchi Method. For this purpose the following factors were studied: austenitizing temperature, tempering condition, grinding condition, subzero treatment, lapping time, $15{\mu}m$ polishing time, final polishing time. These factors were processed and then ten hardness values were measured on each specimen. SN (signal to noise) ratio for each condition was calculated with standard variations of these values. Finally, from the calculated value of ANOVA on SN ratios, the lapping time was found to be the main factor Better uniformity with longer lapping time implies that residual stress that was formed after quenching is a dominent parameter that affects on the uniformity of hardness. Therefore, step-quenching method was adapted to minimize the residual stress. By this modification of quenching procedure, the hardness uniformity was improved remarkably and the yield ratio was increased from 55% to 88%.

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Features of Residual Stress and Plastic Strain in Titanium/Aluminium Friction Welds (티탄과 알루미늄의 마찰용접에서 발생하는 잔류응력.소성변형)

  • 김유철;박정웅
    • Journal of Welding and Joining
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    • v.18 no.5
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    • pp.84-89
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    • 2000
  • Friction welding of titanium and aluminium is numerically modeled by the axisymmetric thermal elastic-plastic analysis. In titanium/aluminium friction welding, heat transfers into the titanium substrate to a distance of z=10(mm) on the side of the bondline and into the whole region of the aluminium substrate having the large thermal conductivity. Adjacent to the bondline, $^{\sigma}r\;and\;^{\sigma\theta}$ are tensile in the substrate whose thermal shrinkage is large, and are compressive in the substrate whose thermal shrinkage is small. $\sigma_z$ along the radial direction is large tensile at the periphery of the component. Plastic strain occurs only close to the bondline in the aluminium substrate. In the components of plastic strain, $\varepsilon^p_r\;and\;\varepsilon^p_{\theta}$ have positive values and $\varepsilon^p_r$ has large negative value. However, $\varepsilon^p_r$ is produced not because of the severity of the mechanical restraint condition, but on purpose to satisfy the condition of the volume constant. A plastic work is proposed as a measure to evaluate the mechanical severity. The plastic work is larger in the aluminium substrate than that in the titanium substrate. The mechanical condition is severer in the aluminium substrate.

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