• Journal of Powder Materials
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• v.2 no.3
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• pp.247-254
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• 1995

The theoretical optimum quaternary composition for improving the thermal stability of Al-Ti alloy was recently proposed. On the basis of the suggestion, quaternary Al-Ti-V-Zr alloy powders corresponding to the optimum compositions, one of which belongs to the region of the smallest lattice misfit between the matrix and the precipitates and the other belongs to the region of the smallest rate constant of coarsening, were prepared by mechanical alloying and the powders were vacuum-hot-pressed at $430^{\circ}C$ under the pressure of 800 MPa. The thermal stability of the specimens was evaluated by hardness testing after isothermal aging up to 400 hrs at various temperatures. The decrease of hardness of Al-Ti-V-Zr alloys was smaller than that of Al-Ti alloys. It was considered to be due to the formation of $Al_3Zr$ type and$Al_3Ti$ type quaternary precipitates having smaller lattice misfit than $Al_3Ti$ and the increase of volume fraction of All0v during the isothermal aging. The quaternary Al-Ti-V-Zr alloys corresponding to the smallest lattice misfit showed the most improved thermal stablilty and it was mainly considered to be due to the formation of All0v.

• Journal of Advanced Marine Engineering and Technology
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• v.24 no.4
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• pp.460-469
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• 2000

A study on the corrosion behavior of RE36 steel for marine structure was investigated with parameters such as micro-Vickers hardness, corrosion potential and corrosion current density measurement of weld metal(WM), base metal (BM) and heat affected zone(HAZ), Al anode generating current and Al anode weight loss quantity in case of cathodic protection. And we carried out slow strain rate test(SSRT) in order to research mechanical properties such as stress at maximum load, percent strain, time to fracture and strain to failure ratio etc and to find out limiting cathodic polarization potential for hydrogen embrittlement with applied cathodic polarization potential. Hardness of HAZ part was the highest among those three parts and also galvanic corrosion susceptibility was the highest in HAZ part among those three parts due to the lowest corrosion potential than other parts. However corrosion current density was the highest in WM part among those three parts. And the optimum cathodic polarization potential showing the best mechanical properties obtained by SSRT method with applied constant cathodic potential was from - 770mV to - 875mV(SCE). However it is suggested that limiting cathodic polarization potential indicating hydrogen embrittlement on the mechanical properties was under - 900mV(SCE).

• Journal of the Korean Society of Food Science and Nutrition
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• v.41 no.9
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• pp.1294-1300
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• 2012

To investigate the effects of oyster mushroom on the quality of Sulgidduk and Gyeongdan, freeze-dried mushroom power and mushroom extract were prepared. Dough for Gyeongdan was held for 0~6 hours at room temperature before cooking in order to allow for enzyme reaction. Upon addition of 2~5% mushroom power or 1~2% mushroom extract, the hardness of Sulgidduk decreased while the storage periods could be extended 1~2 days. Avrami rate constant (k) was 0.0111 for 2% power-added rice cake and 0.044 for the control. In Gyeongdan, hardness also decreased by addition of mushroom. Avrami rate constant (k) was 0.0178 for 10% mushroom power-added Gyeongdan and 0.0652 for the control. In a sensory test, Sulgidduk with 1% mushroom powder showed the highest score. Overall, addition of 1% mushroom powder to rice was appropriate for Sulgidduk. For Gyeongdan, addition of 1~2% mushroom powder was appropriate.

• Korean Journal of Food Science and Technology
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• v.21 no.2
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• pp.313-319
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• 1989

Hydration Properties of Olchal(Japonica type) and Hankangchalbyeo $(J{\times}I\;type)$ waxy rices at soaking temperatures of $4-40^{\circ}C$ were examined. The water uptake rate constant of Olchal was greater than that for Hankangchalbyeo. Volume increase rate during hydration of Olchal was faster. The rate constants of hardness decrease during hydration were similar between the two varieties. The Z-value and $Q_{10}$ were $39.7^{\circ}C$ and 1.78, respectively.

• Korean journal of food and cookery science
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• v.12 no.2
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• pp.162-165
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• 1996

Various kinds of jeolpyon (cubed rice cake) differing in roasted soybean flour. content (0, 5, 10, 15, 20%) were prepared to study digestibility, degree of gelatinization and retrogradation rate. Digestibility slightly in creased as soybean content increased. Degree of gelatinization also increased as soybean content increased. Retrogradation rate obtained from the changes in hardness of soybean jeolpyon with the control was 0.528 day and time constant (1/k) was 1.89 days.

• Journal of Welding and Joining
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• v.34 no.3
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• pp.69-76
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• 2016

Characteristics of dissimilar metal welds between ASTM Type 316L and carbon steel ASTM A516 Gr.70 made with FCAW were evaluated in terms of microstructure, ferrite content, EDS analysis, hardness, tensile strength, impact toughness and corrosion resistance. Three heat inputs of 10.4, 16.9, 23.4kJ/cm were employed to make joints of dissimilar metals with E309LMoT1-1 wire. Microstructure of dissimilar weld metals consisted of mostly vermicular type of ${\delta}$-ferrite and some lathy type of ${\delta}$-ferrite, and ${\delta}$-ferrite was transformed into globular type in reheated zone. In all conditions, weld metals were solidified on FA solidification mode. Based on the EDS analysis of weld metals, All Creq/Nieq values were in the range of FA solidification mode, and it was decreased with increasing heat inputs whereas it was increased with increasing layers. The amount of ${\delta}$-ferrite was decreased with increasing heat input due to the difference of cooling rate, and it was increased with increasing layers. Accordingly, hardness and tensile strength of dissimilar metals weld joints was decreased with increasing heat input while impact energy was increased with increasing heat input. Corrosion test of dissimilar metals weld joints showed that weight gain rate of heat input 10.4kJ/cm was the greatest, and that of three heat inputs became constant after certain time.

• Applied Biological Chemistry
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• v.33 no.4
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• pp.277-281
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• 1990

Injeulmi(Korean glutinous rice cake) was prepared without, 5, 10 and 15% of macerated tea leaves for utilizing unplucked low-graded tea leaves. The effect of firming rate by addition of tea leaf was determined using the Avrami's equation in terms of the texture parameters. Hardness of 5, 10 and 15% addition as compared with no addition was decreased gradually. Overall texture was softened in proportion to Increasing the content of added tea leaf and the addition of 5% and 10% were evaluated as the highest score as an acceptable sensory quality. Avrami exponents and time constant obtained from the Avrami's equation applicable for changes in hardness of without and 10% addition during 7days of storage at $20^{\circ}C$, $90{\sim}95%$ RH indicated 1.062, 15.3 and 0.989, 41.6, respectively, as showing the effect of delay on firming rate.

• Transactions of the Korean Society of Mechanical Engineers
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• v.3 no.2
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• pp.43-47
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• 1979

This paper presents the effect of stress relief annealing on mechanical properties in single Vee-groove welding joint. In this experiment, the investigation of annealing effect on mechanical properties of test material carried out by changing the annealing temperature from $600^{\circ}C$ to $900^{\circ}C$ under the given conditions. The results pbtained by this study are as follows: (1) Under the constant welding conditions, the tensile strength of test welded joint decrease in accordance with the increase of annealing temperature. The experimental results show that the reduction rate of tensile strength is about 35.09% of base metal strength. (2) Microhafdness distribution of welded joint bring about the maximum hardness near the bended line of welding joint. (3) Izod impact energy of welded joint in increase in according to the rise of annealing temperature and the peak energy of impact test occurs at $800^{\circ}C$

• Journal of the Korean Society for Heat Treatment
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• v.7 no.2
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• pp.88-95
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• 1994

In order to compare mechanical properties of ausformed martensite with those of marformed martemsite in Fe-30%Ni-0.1%C alloy and to investigate their strengthening mechanisms, ausformed martensite and marformed martensite were prepared by ausforming treatment and marforming treatment respectively. The microstructures were observed and the quantities of retained austenite, hardness, yield strength, ultimate tensile strength and elongation were examined. The strength of ausformed martensite was mainly increased because of the lattice defects inherited from austenite. The ductility of ausformed martensite was constant at the rate of 7-8% by ductile matrix formation of the retained austenite in spite of the increase in strength. The strength of marformed martensite was increased by the increment in dislocation density, the crossing of transformation twin with deformation twin and the mutual crossing of deformation twin. The ductility of mar formed martensite was slightly lower than that of ausformed martensite, but the strength of mar formed martensite was prominently higher.

• Applied Biological Chemistry
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• v.32 no.4
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• pp.332-337
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• 1989

Rheological properties of rehydrated freeze dried instant rice were investigated in comparison with that of cooked rice. The time changes in reciprocal hardness of instant rice grains at various rehydration temperatures$(60{\sim}90^{\circ}C)$ could be expressed by the first order reaction rate equation regardless of rehydration temperature and reaction rate constant increased as the rehydration temperature increased. Activation energy for rehydrating instant rice was 6.1 kcal/g-mol. Analysis of compressive stress relaxation test showed that the viscoelastic properties of both rehydrated instant rice and cooked rice grains could be expressed by 6-elements generalized Maxwell model. Rehydrated instant rice revealed higher relaxation decay than that of cooked rice and showed the elastic property increased by increasing the rehydration temperature.