• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.932-934
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• 2006

A relationship between discharge delay time and the aging method were investigated: A-Y (Address electrode - Scan electrode) aging and conventional X-Y(Common electrode - Scan electrode) aging with the variation of sustain voltage beyond self-erasing discharge. Although A-Y aging decreases discharge delay time, it has several drawbacks like non-uniformity of discharge, degradation of luminous efficiency and a color temperature. In a conventional aging condition which is carried out near the mid-margin voltage, discharge delay time is short in low voltage and high frequency condition. As an alternative to conventional voltage aging, high voltage aging is suggested which is carried out at self-erasing sustain voltage region. High voltage aging shows lower discharge delay time and fast aging speed than conventional voltage aging.

• Korean Journal of Materials Research
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• v.4 no.5
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• pp.524-534
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• 1994

The effects of transformation temperature and mechanical properties by thermal cycle of CuZnAl shape memory alloy with a small of misch metal and Zr contents were investigated. The addition of misch metal and Zr was very effective for reducing the grain size. After solution treatment, the specimens were post-quench aged or step quenched at $100^{\circ}C$ to $350^{\circ}C$ for variation of Rockwell hardness value. It was found that the Rockwell hareness value was very increased at $200^{\circ}C$ and $250^{\circ}C$. The fracture strength and ductility have been significantly increased with the increase of misch metal conten when tensile tested below $M_f$ temperature. Also, the fracture strength has been more increased in the case of post quench aging treatment than that of the as-quenching treatment. Aging of the $\beta$-phase decreases the $M_s$ temperature, but that of the martensite phase increases the $A_s$ temperature. The change in $A_s$ temperature with post-quench aging can be attributed to recovery of order in the $\beta$phase. The hystersis of transformation temperature ($A_s-M_s$) has an increasing tendency by thermal cycles.

• Korean Journal of Food Science and Technology
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• v.37 no.3
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• pp.389-396
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• 2005

Physico-chemical properties of ssamjang prepared by industrial process were investigated. Overall experiments were planned by central composite design for five independent variables, kochujang mash aging period $(X_{1})$, doenjang aging period $(X_{2})$, doenjang content $(X_{3})$, sterilization temperature $(X_{4})$, and storage temperature $(X_{5})$. Storage period had no consistent effect on moisture content of ssamjang. Doenjang having longer aging period showed lower moisture content than that having shorter aging period. Titratable acidity and pH of ssamjang gradually increased and decreased with storage period, respectively, with pH of ssamjang significantly affected by aging period of doenjang and kochujang mashes, and sterilization and storage temperatures. Amino nitrogen contents of ssamjang increased during storage and were more affected by sterilization temperature than by aging period and content of doenjang, and storage temperature. Crude protein content of ssamjang irregularly changed during storage, and was slightly affected by content of doenjang.

• Journal of the Korean Society for Nondestructive Testing
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• v.22 no.3
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• pp.284-291
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• 2002

An attempt was made to evaluate the degree of aging degradation in thermally aged 2.25Cr-1Mo steel by electrical resistivity measurement. Artificial aging was performed to simulate the microstructural degradation in 2.25Cr-1Mo steel arising from long time exposure at $540^{\circ}C$. Microstructural parameter (amount of solid solution element), mechanical property (ductile-brittle transition temperature) and electrical resistivity were measured to investigate the mutual relationship among these parameters. Depletion of solid solution element(Mo and Cr) in matrix was detected after aging. The ductile-brittle transition temperature(DBTT) increased rapidly in the initial stage of aging and then saturated afterward. On the other hand, the electrical resistivity decreased rapidly in the beginning and then saturated in the later stage of aging.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05c
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• pp.79-84
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• 1996

Small punch test was performed on CF8 duplex stainless steel aged at 370 and 400$^{\circ}C$ up to 5,000 h to evaluate the degree of the thermal aging embrittlement. At room temperature, the SP load-displacement curve was in a similar shape to those of ferritic steels and had a good reproducibility in spite of two-phase structure. The aging heat treatment resulted in a slight increase of the yield strength. As test temperature was lowered, the SP load showed a sudden drop followed by serrations before the SP specimen was fractured, resulting from the cracking of ferrite phase. The extent of thermal embrittlement was assessed in terms of the SP energy. Aging treatment at higher temperature led to a larger shift in the transition temperature and the corresponding change in the fracture mode. The main cause of the degradation was the embrittlement of ferrite phase. Additionally the phase boundary separation profoundly contributed to the degradation of the specimen aged at 400$^{\circ}C$.

• Journal of the Korean Society for Heat Treatment
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• v.32 no.5
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• pp.212-223
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• 2019

This study is to investigate the relationship between microstructural factors and tensile properties after aging heat treatment of the 15-5PH stainless steel at the temperature range of $450^{\circ}C$, $500^{\circ}C$ and $550^{\circ}C$ for various time. For the aging time of 2 hours, hardness showed maximum at $450^{\circ}C$ and then decreased with increasing aging temperature. While, hardness decreased gradually during aging $450^{\circ}C$, $500^{\circ}C$ and $550^{\circ}C$ from 1 hour to 5 hours but the hardness nearly unchanged until the 100 hours after 5 hours aging. When aging at $450^{\circ}C$, Cu atoms preferentially aggregated at the prior austenite grain boundaries and martensite lath boundaries, and Cu concentration at those boundaries was nearly unchanged even after aging for 100 hours. Therefore it was suggested that the coherency is still maintained after 100 hours aging at $450^{\circ}C$. Aging at $500^{\circ}C$ and $550^{\circ}C$ results in an increase in the concentration of Ni at the martensite lath boundaries and prior austenite grain boundaries, resulting in the formation of reversed austenite. Especially, when aged at $550^{\circ}C$ for 100 hours, the concentration of Ni remarkably increased at those boundaries, and thus the microstructure of herring bone shape was appeared. Considering the migration of Ni atom to the lath boundaries and prior austenite grain boundaries, Ni atoms contributed greatly to the formation of reversed austenite. On the other hand, it was found that Cu atoms hardly moving to those boundaries may not be contributed to the formation of reversed austenite. When aging at $450^{\circ}C$, the coarsening of the precipitated Cu atoms proceeded very slowly with increasing aging time, therefore the decrease in strengths were small but the reduction area was considerably increased due to the softening of the matrix. At the aging temperature of $500^{\circ}C$ and $550^{\circ}C$, the strengths decreased and the elongation and reduction area increased due to the appearance of the reversed austenite. Especially, the increase of reduction area was remarkable.

• Korean Journal of Materials Research
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• v.14 no.1
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• pp.13-18
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• 2004

Titanium alloys are the one of promising candidate materials for medium high temperature parts in the aircraft, automobile, petrochemistry and electrochemistry because of their high strength with low density in medium high temperature. In this study, the effects of aging and heat treatments on the mechanical properties of Ti-15-3 alloy in medium high temperature, which was $400^{\circ}C$, were studied. Solid solution treatment was performed at $8000^{\circ}C$ of $\beta$ phase region for 1 h and the alloy was quenched in water. The alloy was aged at $5000^{\circ}C$ of $\alpha$ and $\beta$ two-phase region for 1, 2, 4, 8, ... and 100 h to increase the mechanical property. The $\beta$ single phase was observed at all parts of specimens in Ti-15-3 alloy after ST. As the aging at $500^{\circ}C$, fine precipitates of a phase was generated from matrix of $\beta$ phase and the microstructure was consisted of weaving structure such as Widmanstiitten a phase. The most suitable aging time is 24h in$ 400^{\circ}C$. At this time, strength is 1164 MPa and elongation is about 12%. In room temperature, elongation of Ti-15-3 alloy aged at $500^{\circ}C$ for 16 h is poor (=3%) in spite of high tensile strength (1458 MPa).

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.3
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• pp.244-252
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• 2002

The electrical and dielectric behavior fort DC accelerated aging stress of P $r_{6}$ $O_{11}$-based Zno varistors cnsisting of ZnO-P $r_{6}$ $O_{11}$-CoO-C $r_2$ $O_3$-E $r_2$ $O_3$ were investigated with sintering temperature in the range of 1325~1345$^{\circ}C$. The varistor ceramics with increasing sintering temperature were more densified. A more densified varistors leaded to high stability for DC accelerated aging stress. Furthermore, the stability for DC accelerated aging stress was increased with the leakage current and dtan $\delta$/dV decreasing in order of 1325longrightarrow1335longrightarrow1345longrightarrow134$0^{\circ}C$ in sintering temperature. It was found that the stability for DC stress is affected more greatly by the leakage current and dtan $\delta$/dV than the densification. It is considered that the stability of varistors for DC stress can be estimated by considering the factors, such as the densification, leakage current, and dtan $\delta$/dV. As a result, the varistor sintered at 134$0^{\circ}C$ exhibited the highest stability, with %$\Delta$ $V_{lmA}$=-1.54%, %$\Delta$$\alpha$=-2.49%, %$\Delta$ $I_{\ell}$=+240.68%, 5%$\Delta$tan$\delta$=+29.96%.96%.96%.%.

• Journal of the Korean Society of Food Science and Nutrition
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• v.30 no.1
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• pp.70-74
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• 2001

The effects of aging time (1, 8 and 15 days) and endpoints cooking temperature (70, 75 and $80^{\circ}C$) on the physicochemical and sensory characteristics of pork neck were evaluated. Pork neck was obtained from the carcass (live weight, 105~110 kg ; grade B) chilled for 24 hours after slaughter. As a aging period became longer, the pH, L value and drip loss became higher while its a value and shear force value (SFV) of raw meat became lower. As a aging period became longer, the cooking loss, hardness, chewiness, SFV became lower, and its tenderness, juiciness and taste became better. However, no difference was observed in the aroma, and the one aged for 8 days in the cooked meat showed the best palatability. Increasing endpoint cooking temperature from 70 to $80^{\circ}C$ increased hardness, SFV and taste, and decreased chewiness, sensory tenderness and juiceness (p<0.05). However, it had no effect on the cohesiveness. Also, the one for which the endpoint cooking temperature became $75^{\circ}C$ in the cooked meat showed the best springiness, aroma and palatability.

• Journal of the Korean Society for Heat Treatment
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• v.13 no.1
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• pp.1-9
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• 2000

The microstructural characteristics and low temperature tensile properties between $25^{\circ}C$ and $-196^{\circ}C$ for as-welded and age hardened specimen by using Al 5083-H321 for base metal, 5083-5356 and 5083-4043 weldments have been investigated. The hardness of 5083-5356 weldment decreases with aging treatment, whereas the weld region of 5083-4043 weldment shows remarkable increase in hardness after aging due to the precipitation of fine Si particle at the grain boundaries and interiors. Low temperature tensile properties of 5083 AI base metal, 5083-5356 and 5083-4043 weldments appear to be the increment of tensile strengths and elongations at the room temperature and $-196^{\circ}C$, while the decrement of tensile properties around $-50^{\circ}C$ is shown. Through the observation of fine serration to fracture in the stress-strain curve and tensile fractography, the increment of localized deformation leading to promote the neck initiation and the increment of the dimple size cause to decrease in tensile strengths and elongations around $-50^{\circ}C$. For the tensile specimen of the 5083 base metal, 5083-5356 and 5083-4043 weldments, the reason to increase in elongation after solution and aging treatment is the diminishment of fine pit, the resolution of Mg into the matrix and the spheridization of the eutectic Si.