• Journal of the Korean Society of Hazard Mitigation
• /
• v.8 no.3
• /
• pp.165-169
• /
• 2008

It has been reported that most wastewater treatment plants have difficulties in nitrogen removal during winter season due to declined activity of nitrifiers in the condition of low temperature. This study was conducted in order to find out optimum operating condition for efficient nitrogen removal in low temperature. A series of operating conditions with various HRTs of each tank were simulated using the GPS-X program. The optimum HRT combination for effective nitrogen removal was 0.3 hr/0.5 hr/1.36 hr/4.84 hr(PreAx/An/Ax/Ox) with 51.4% of T-N removal efficiency and 57.3% of $NH_4^+$-N removal efficiency.

• Journal of the Korean Society of Costume
• /
• v.56 no.1 s.100
• /
• pp.143-149
• /
• 2006

For the purpose of standardization and practicability of natural dyeing, the mordanting and dyeing properties of Acorn Shell was studied. Appropriate extraction, dyeing and mordanting condition of Acorn Shell were determined, and the effect of mordanting method on dye uptake and color fastness of dyed fabric was investigated. The maximum absorbance of Acorn Shell solution was at 287.5nm and 294nm. The pH effect was stable in the color difference changes. The optimum temperature to extract Acorn Shell was during 1 hour in $60^{\circ}C$. The effective dyeing temperature and time of silk were $80{\sim}100^{\circ}C$, 1hour. The silk fabrics dyed with Acorn Shell appeared yellow-brown. K/S value of dyeing fabrics was increased by mordant treatment. K/S value of post-mordanting was higher than pre-mordanting. Mordanting treatment attected color change of the dyed silk. In the case of Acorn Shell light fastness of appeared more than 3-5grades by post-mordanting. Abrasion fastness of appeared more than 3-5grades. Perspiration fastness of appered more than $3{\sim}5grades$ by mordant treatment but Cu mordant treatment was $2-5{\sim}4grades$. Dry-cleaning Fastness appered more than 4 grades except Cu mordant treatment. These fastness improvement were generally effective for mordant treatment, specially Al, Sn, Cr.

• Korean Journal of Medicinal Crop Science
• /
• v.27 no.6
• /
• pp.390-396
• /
• 2019

Background: Usually ginseng seeds are sown during autumn and spring. Sowing in spring often results in poorer seedling establishment than in autumn. One of the reasons for poor germination could be cold-treatment condition for breakage of physiological dormancy during winter. Here we tested the effects of storage temperature used during cold treatment on germination. Methods and Results: Germination properties were observed after dehiscent seeds were stored as wet and dry at 2℃, -2℃, -3.5℃ and alternating temperature (AT). Seed dryness and storage temperature affected germination properties (p < 0.01). Wet and AT condition germinated highest, and wet and -3.5℃ condition germinated lowest, which was 91.2% and 1.4% respectively. Mean germination time (MGT) of the wet and AT condition was faster than other treatments at 2.4 days, and the dry and -2℃ condition was the longest. Germination performance index (GPI) was highest for wet and AT condition (37.7%) and the lowest for wet and -3.5℃ condition (0.5%). The growth of above-ground and below-ground were the best for wet and 2℃ condition, and wet seeds showed better growth than dry seeds (p < 0.01). Conclusions: For cold treatment, ginseng seeds may not be stored below -2℃ for successful germination during spring sowing.

• Journal of Korea Foundry Society
• /
• v.26 no.6
• /
• pp.249-257
• /
• 2006

The effects of alloying element and the condition of heat-treatment on the strength of squeeze-cast Al-3.0 wt%Si alloy were investigated. The strength of the alloy without grain refinement was increased with increase Cu content upto 3.0 wt% and rather decreased beyond that. The tensile strength of the alloy with grain refinement increased with Cu content upto 3.0 wt% and not changed beyond that. The strength of the alloy without grain refinement increased with the Mg content. The tensile strength with grain refinement increased with the Mg content upto 0.50 wt% and then decreased beyond that. The strength of the grain refined alloy increased by individual and simultaneous additions of Cu and Mg and the maximum strength was obtained with Al-3.0 wt%Si-4.5 wt%Cu-0.50 wt%Mg alloy. The optimum heat-treatment condition for this alloy was obtained.

• Proceedings of the Korean Society of Crop Science Conference
• /
• 2022.10a
• /
• pp.100-100
• /
• 2022

This study was conducted in 2021 using Kwangpyeongok and Gangdaok, that showed good yield performance both under upland and lowland conditions in the previous year. The experiments were carried out by sowing on April 22, May 14, May 30, June 19, and July 10, with aim to determine optimum sowing date in central region of Korea. The growing degree days (GDD) required to read the flowering stage were 1375.5-1725.3℃ for upland and 1582.7-1982.4℃ for lowland condition. The lowest GDD was observed in July 10 sowing regardless of ridge formation both under lowland and upland conditions for Kwangpyeongok. However, Gangdaok showed the lowest GDD under no-ridge in lowland and high-ridge in upland, both of which were sown on June 19. The difference in GDD between no-ridge and high-ridge treatment was little depending on the sowing date. In both lowland and upland, there was no significant difference between no-ridge and high-ridge treatments in stover dry matter, ear dry matter, and TDN between no-ridge and high-ridge treatments. Under upland condition, no significant difference in biomass and TDN was observed among sowing date treatments and between varieties. Under lowland condition, biomass production was severely reduced in May 30 sowing treatment, whereas no varietal difference was observed. Reduced biomass in May 30 sowing treatment may be due to excess waterlogging and lodging by rainfall.

• Korean Chemical Engineering Research
• /
• v.48 no.5
• /
• pp.556-560
• /
• 2010

An atmospheric surface modification using plasma treatment method was applied to butadiene rubber to improve its adhesion strength by plate type reactor. In order to investigate the optimum reaction condition of plasma treatment, type of reaction gas(nitrogen, argon, oxygen, air), gas flow rate(30~100 mL/min), treated time(0~30 s) and primer modification method(GMA, 2-HEMA) were examined in a plate type plasma reactor. The results of the surface modification with respect to the treatment procedure was characterized by using SEM and ATR-FTIR. As the gas flow rate and treated time increases the contact angle decreases. The greatest adhesion strength was achieved at optimum condition such as flow rate of 60 mL/min, treated time 5 s and modification primer containing 2-HEMA for air. Due to the atmospheric surface modification using plate plasma method consequently reduced the wettability of butadiene rubber and resulted in the improvement of the adhesion.

• Journal of Adhesion and Interface
• /
• v.10 no.3
• /
• pp.148-153
• /
• 2009

An atmospheric plasma pre-treatment method was applied to PU foam, Leather (Action), Rubber to improve its adhesion using solvent and water soluble type pressure sensitive adhesion in atmospheric plate type reactor. In order to investigate the optimum reaction condition of plasma treatment, type of reaction gas (nitrogen), rate of gas flow (30~100 mL/min), and reaction time (0~30 s) were examined in a plate plasma reactor. The result of the surface modification with respect to the treatment procedure was characterized by using SEM. Due to a de-crease of the contact angle of various materials, the greatest adhesion strength was achieved at optimum condition such as flow rate of 100 mL/min, reaction time of 10 second for an atmospheric plasma treatment of the PU foam, EVA foam, Leather (Action) and Rubber also resulted in the improvement of the adhesion.

• Journal of the Korean Society for Heat Treatment
• /
• v.34 no.5
• /
• pp.233-238
• /
• 2021

The mechanical, anti-tarnishing, and corrosion characteristics of Yuggi (Cu-22wt%Sn) alloy are greatly affected by fraction of constituent phases according to heat treatment method. The Yuggi heat-treated at 750℃ has a β1' phase of 98% or more, which is a high-temperature disordered beta phase, on the other hand, cast Yuggi that Sn is solid-solutioned into Cu consists with α-phase over 60v/o. This difference of constituent phases of Yuggi may cause a difference in dissolution of Cu under antimicrobial test condition. Nonetheless, few studies have been conducted on the effect of fraction of constituent phases and constituent phases in antimicrobial activity. In addition, few studies have also been conducted on the suitable method measuring the antimicrobial activity of Yuggi. Hence, the purpose of this study is to provide an optimum measurement method of antimicrobial activity, and to evaluate quantitatively the effect of constituent phases on antimicrobial activity.

• Journal of Life Science
• /
• v.18 no.8
• /
• pp.1096-1105
• /
• 2008

This study was carried out to identify the optimum condition for priming, as a series of experiments for the enhancement of germination percentage and germination synchronization in cool-season turfgrass seeds. The optimum priming conditions to maximize the germinability in both Kentucky bluegrass and Tall fescue was a 1 day treatment of 100 mM $K_3PO_4$ at $25^{\circ}C$. The seeds treated with the optimum priming condition enhanced the germinability compared to control, and shortened the time for germination with reduced $T_{50}$ and mean daily germination (MDG). However, as the concentration and treatment period of NaOH or KOH increased, significantly decrease in germination percentage was observed. Germination percentage in Creeping bentgrass and Bentgrass was below 10%, regardless of priming treatment. However, the priming treatment with 200 mM $KNO_3$ for three days improved the germination up to 6%, which was not a statistically significant level. The most effective priming period for Kentucky bluegrass and Tall fescue was one day treatment, but the germinability was suppressed as the treatment period was extended until six days. For priming chemical treatment, germinability was improved with the concentration of 100 mM, while it was reduced at higher concentrations of 200 mM and 300 mM.

• Journal of Environmental Health Sciences
• /
• v.34 no.3
• /
• pp.233-239
• /
• 2008

In order to improve reactor performance of existing sewage treatment plants, the feasibility of enhancing reactor performance by bioaugmentation using EM as bioaugmentation agent and the effects of anoxic: oxic time ratio on reactor performance were investigated. Continuous and intermittent aeration modes were compared under the 6 hr of HRT. Three different types of intermittent aeration modes, that is, 15 min, of anoxic:45 min of oxic, 30 min of anoxic: 30 min of oxic, and 45 min of anoxic: 15 min oxic respectively were chosen as test modes to study the effects of anoxic : oxic time ratios on reactor performance. The optimum anoxic: oxic time ratio was 30 min:30 min when considering simultaneous removal of organic, nitrogen and phosphorus. When applying EM into a continuously aerated reactor under the varying dosing rates of 50-200 ppm, reactor performance in terms of organic and nitrogen removal efficiencies was not improved at all. Nitrogen removal efficiency was increase when the EM dosing rate was increased. However the degree of improvement was slight when the EM was injected above 100 ppm. However optimum phosphorus removal was found at the EM dosing of 200 ppm. Thus it was found that optimum injection concentration of EM is 200 ppm. It is apparent that putting EM into a sewage treatment plant significantly affects the T-N removal efficiency of the reactor by enhancing denitrification efficiency especially in operational conditions of relatively long anoxic periods. To achieve reciprocal condition in a reactor with intermittent aeration it is necessary to enhance the reactor performance by EM injection. In the case of modifying existing continuously aerated reactors into intermittent aerated reactors, it is obvious that operating costs of aeration would be reduced by reducing aeration time when compared with existing conventional sewage treatment plants.