• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.7
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• pp.63-68
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• 2003

Shot peening process is most often used to improve the fatigue properties of metal parts, In order to achieve an optimum, repeatable, and reliable fatigue enhancement from the shot peening process, the important shot peening parameters must be optimized, In this paper, the optimum peening intensity(Almen intensity) condition is investigated by experiment. Rotary bending fatigue test has been adopted to investigate the effects of optimum peening on the fatigue characteristics, Experimental results show that the fatigue strength and fatigue life has been tremendously increased by optimum-peening treatment. However, the fatigue strength and fatigue life has been decreased by under or over peening.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.54 no.4
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• pp.416-421
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• 2009

This experiment was conducted to find out optimum priming treatment conditions to the sesame seed as a preliminary study for enhancing sesame germination properties. Effective priming agents and concentrations for sesame seed were $K_3PO_4$, 200 mM and PEG6000, -1.0 MPa respectively. Optimum priming temperature and duration were $15^{\circ}C$, 4 days in view of germination speed and germination percentage. PEG6000 with -1.0 MPa was selected as an efficient priming treatment condition at $15^{\circ}C$, 4 days. This study suggested that priming treatment to sesame seed would be an effective technique enhancing sesame seed germination and shortening time to the $T_{50}$ at the field condition, but the efficiency of priming treatments to the sesame seed would be strongly dependent on individual or integrated conditions of priming agent, concentration, temperature and duration etc.

• Elastomers and Composites
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• v.50 no.1
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• pp.30-34
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• 2015

Thermo-mechanical treatment process of a compressed open-cell rigid polyurethane foam (OC-RPUF), which was fabricated for the vacuum insulation panel (VIP), was studied to obtain an optimum condition for the dimensional stability by the relaxation of compressive stress. Thermo-mechanical deformation of the sample OC-RPUF was shown to occur from about $120^{\circ}C$. Yield stress of 0.36 MPa was shown at about 10% yield strain. And, densification of the foam started to occur from 75% compressive strain and could be continued up to max. 90%. Compression set of the sample restored after initial compression to 90% at room temperature was ca. 82%. Though the expansion occurred to about twice of the originally compressed thickness in case of temperature rise to $130^{\circ}C$, it could be overcome and the dimensional stability could be maintained if the constant load of 0.3 MPa was applied. As the result, a thermo-mechanical treatment process, i.e, annealing process at temperature of $130{\sim}140^{\circ}C$ for about 20 min as is the maximum compressed state at room temperature, should be required for dimensional stability as an optimum condition for the use of VIP core material.

• Journal of the Korean Wood Science and Technology
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• v.28 no.3
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• pp.9-13
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• 2000

Wood demand is increasing more and more, but world has been confronted with decreasing forest resources. Korea has to depend upon foreign wood and wood-based products for more than 95 percent of total domestic demand per year. In order to heighten self-sufficiency for wood supply and demand, we have to develop wood substitutes. Rice hull is the cheapest agricultural by-product we can get in Korea, more over the production of rice hull amounts to 1 million tons per year. This study was carried out to utilize rice hull and to decide the optimum condition of rice hull pretreatment for manufacture of rice hull board. Steam explosion method gave the best result, and the next boiling treatment of 1 hour, the last 1 hour treatment with 1% NaOH solution. Optimum conditions of explosion method were 20kgf/$cm^2-1$ minute and 25kgf/$cm^2-1$ minute. Rice hull board made with exploded rice hull met the KS standard(KS F 3104, 1997) and showed the same strength as a control, PB. And also the 1 hour boiling treatment was more effective than the 1 hour treatment with 1% NaOH solution.

• Proceedings of the KSME Conference
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• 2000.04a
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• pp.803-808
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• 2000

This thesis studied whether friction welding of SPSS, localized torsion bar material could be accomplished or not. And then optimum welding conditions were examined and leaded through tensile, impact, torsion and hardness test after postweld heat treatment of the actual field condition. Obtained results were as follows; Linear relationship was existed between heating time and total upset, and a quadratic equation model could be made between tensile strength and heating time. Optimum welding conditions with fine structure were as follows in case total upset(U)=8.5mm; the number of rotations(n)=2,000 rpm, heating pressure($p_1$)=80MPa, upset pressure($p_2$)=200MPa, heating time($t_1$)=4sec, upset time($t_2$)=3 sec.

• Korean Journal of Medicinal Crop Science
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• v.18 no.1
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• pp.9-14
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• 2010

Several presowing seed treatments have been used to facilitate the seed germination and seedling emergence. The study was performed to design a model of presowing seed treatments in Taraxacum platycarpum. Germination and seedling growth responses to temperature, drying, chilling, $GA_3$ and priming were investigated to know the optimum germination conditions and presowing treatment. The optimum temperature condition for germination and seedling growth were $15{\sim}20^{\circ}C$ at dark condition. The seeds exposed to infra red light, however, did not germinate. The moisture content of seeds dried at $35^{\circ}C$ for 3.5 hours was returned to the level of unimbibed seeds. The germination of seeds dried under dark condition was better than those dried under infra red light. Prechilling treatment imposed for 6 weeks showed higher germination rate than $GA_3$ treatment or priming. In field test, the highest field emergence was observed in the seeds dried after prechilled for 6 weeks and followed by drying followed by $GA_3$ > low temperature > $KNO_3$ priming. Imbibition with 0.1 mM $GA_3$ solution for 2 hours then drying at 35 for 3.5 hour under dark condition was effective to the practical presowing treatment for Taraxacum seeds.

• Journal of the Korean Professional Engineers Association
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• v.31 no.5
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• pp.110-120
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• 1998

The effect of heat treatment and the order of antioxidants treatment toward the thermally oxidized palm oil which has been stored at 60 $^{\circ}C$ was studied. The summerized results of this study are as follows; 1. In the accelerated autoxidation condition, tocopherol showed no distinct effect on the changes of peroxide of value between added tocopherol samples pre-and post treatment by heating. But, rosemary extract showed opposite result. It was supposed that rosemary extract had lower thermostability then tocopherol, because rosemary extract lost it's antioxidative activity during heating process. 2. The changes of acid value and anisidine value were more affected by heat treatment than the order of antioxidant treatment. 3. The oxidative stability measured by OSI showed same tendency as peroxide value. That is, the antioxidative activity of tocopherol in palm oil was more dependent on addition of antioxidants than heat treatment, but the rosemary extract had opposite character for antioxidative action in palm oil.

• Journal of the Korean institute of surface engineering
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• v.16 no.3
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• pp.98-107
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• 1983

A study on the improvement of wear resistance of brasses by electroplating and diffusion treatment of tin was carried out. The optimum condition of the treatment obtained was as follows. Plating thickness of tin : 5 - 9 $\mu\textrm{m}$ Condition of diffusion treatment : atmosphere ; fused nitrate bath (KNO3 + NaNO3) temperature and time ; 1st step 320$^{\circ}C$, 60min. and 450$^{\circ}C$, 30min. During the diffusion treatment, internetallic compounds of Cu-Sn were formed and these compounds were identified as η, $\varepsilon$ and $\delta$ phase from the outer tin layer. It was considered that the improvement of wear resistance of brasses by the treatment is because of the formation of intemetallic compounds particalarly $\varepsilon$phase which is very hard, between soft tin layer brass.

• Journal of the Korean Society for Heat Treatment
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• v.11 no.2
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• pp.121-130
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• 1998

The effects of alloying elements(Mo, Cu, Ni) and austempering temperature conditions on the microstructural morphologies and mechanical properties in austempered ductile cast iron has been investigated. The austempering at $350^{\circ}C$ for 2hrs after austenitizing at $900^{\circ}C$ for 2hrs in all specimens with various alloying elements was optimum because the good combination of tensile and yield strength, hardness and impact value was obtained. The microstructures of these ADIs treated by a forementioned austempering condition are nearly a mixture type of needle and feathery bainite. Among those alloys, Mo-Cu alloyed DCI had the best optimum mechanical properties of hardness and toughness for automobile parts by austempering treatment for 2hrs at $900^{\circ}C$ followed by $350^{\circ}C$ for 2hrs.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08b
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• pp.1534-1536
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• 2007

ZnS-based orange-emitting phosphors were synthesized by two-step firing process: above $1000^{\circ}C$ to obtain hexagonal phase, and at $750^{\circ}C$ for cubic phase. The effect of heat treatment condition on the optical properties was investigated to fine an optimum condition for high-performance ZnS:Mn,Cu,Cl phosphor.