• Korean Journal of Materials Research
• /
• v.22 no.11
• /
• pp.591-597
• /
• 2012

For heat exchanger applications, 2-ply clad materials were fabricated by rolling of aluminum (Al) and mild steel sheets. Effects of annealing temperature on interface properties, especially on inter-layer formation and softening of strain hardened mild-steel, for Al/mild steel clad materials, were investigated. To obtain optimum annealing conditions for the Al/mild steel clad materials, annealing temperature was varied from room temperature to $600^{\circ}C$. At the annealing temperature about $450^{\circ}C$, an inter-layer was formed in an island-shape at the interface of the Al/mild steel clad materials; this island expanded along the interface at higher temperature. By analyzing the X-ray diffraction (XRD) peaks and the energy dispersive X-ray spectroscopy (EDX) results, it was determined that the exact chemical stoichiometry for the inter-layer was that of $Fe_2Al_5$. In some samples, an X-layer was formed between the Al and the inter-layer of $Fe_2Al_5$ at high annealing temperature of around $550^{\circ}C$. The existence of an X-layer enhanced the growth of the inter-layer, which resulted in the delamination of the Al/mild-steel clad materials. Hardness tests were also performed to examine the influence of the annealing temperature on the cold deformability, which is a very important property for the deep drawing process of clad materials. The hardness value of mild steel gradually decreased with increasing annealing temperature. Especially, the value of hardness sharply decreased in the temperature range between $525^{\circ}C$ and $550^{\circ}C$. From these results, we can conclude that the optimum annealing temperature is around $550^{\circ}C$ under condition of there being no X-layer creation.

• Journal of Korean Society on Water Environment
• /
• v.31 no.2
• /
• pp.181-195
• /
• 2015

Algal blooms in lakes are one of major environmental issues in Korea. A three-dimensional, hydrodynamic and water quality model was developed and tested in Lake Euiam to assess the performance and limitations of numerical modeling with multiple algal groups using field data commonly collected for algal management. In this study, EFDC was adopted as the basic model framework. Simulated vertical profiles of water temperature, dissolved oxygen and nutrients monitored at five water quality monitoring stations from March to October 2013, which are closely related to algal dynamics simulation, showed good agreement with those of observed data. The overall spatio-temporal variations of three algal groups were reasonably simulated against the chlorophyll-a levels of those estimated from the limited monitoring data (chlorophyll-a level and cell numbers of algal species) with the RMSEs ranging from 2.6 to $17.5mg/m^3$. Also, note that $PO_4-P$ level in the water column was a key limiting factor controlling the growth of three algal groups during most of simulation period. However, the algal modeling results were not fully attainable to the levels of observation during short periods of time showing abrupt increase in algae throughout the lake. In particular, the green algae/cyanobacteria and diatom simulations were underestimated in late June to early July and early October, respectively. The results shows that better understanding of internal algal processes, neglected in most algal modeling studies, is necessary to predict the sudden algal blooms more accurately because the concentrations of external $PO_4-P$ and specific algal groups originated from the tributaries (mainly, dam water releases) during the periods were too low to fully capture the sharp rise of internal algal levels. In this respect, this study suggests that future modeling efforts should be focused on the quantification of internal cycling processes including vertical movement of algal species with respect to changes in environmental conditions to enhance the modeling performance on complex algal dynamics.

• Korean Journal of Weed Science
• /
• v.15 no.3
• /
• pp.214-223
• /
• 1995

Tolerant corn cultivars to bentazon were selected and tolerance mechanism of corn cultivars to bentazon was studied by determining bentazon 6-hydroxylase(B6H) activity which was known to detoxify bentazon to 6-hydroxy bentazon at induced enzyme conditions with treatments of 1,8-naphthalic anhydride, ethanol and phenobarbital. Tolerant cultivars to bentazon were selected by growth response of corn by foliar application of bentazon to corn cultivars. Kwanganok, GA 209, IK 2, DB 544, and Suwon 19 were tolerant to bentazon, but KSS 3, KSS 4, KS 5, and Danok 2 were susceptible. Pretreating corn seeds with 1,8-naphthalic anhydride increased B6H activity at all cultivars, but the tendencies were more remarkable at Suwon 19 and GA 209, tolerant cultivars, than at Danok 2 and KS 5, susceptible cultivars. Treating corn shoots with ethanol increased B6H activity at Suwon 19 and GA 209. B6H activity was enhanced by treatments of ethanol at 1.0 or 2.5%, but decreased at ethanol 2.5 or 5.0% at Danok 2 and KS 5. Treating corn shoots with phenobarbital increased B6H activity at Suwon 19, GA 209, Danok 2, and KS 5 by treatments of phenobarbital at 2.0mM, but decreased at 4.0 or 8.0mM at all cultivars. Therefore, the tolerant mechanism of corn cultivars to bentazon may be explained partially by the activity of bentazon 6-hydroxylase which detoxifies bentazon to 6-hydroxy bentazon.

• Journal of Life Science
• /
• v.17 no.7 s.87
• /
• pp.956-963
• /
• 2007

The purpose of the present study was to examine the effects of iron shot practice volume based on golf skill level on the indices of muscle damage and fatigue in blood. Twenty four golf players were studied under conditions of different golf skill level (beginners, intermediate, expert) and practice volume (100, 200, 300balls). In this study blood CK and LDH were determined to show the level of muscle damage, and blood phosphorus, lactate, and ammonia were measured to see the level of fatigue. Blood creatinine, and IGF- I generally used to see the rate of protein synthesis were also measured. In summary, these results are interpreted to mean that 1) blood fatigue factors, muscle damages, and creatinine levels increased due to a rise in the practice volume of iron shot, 2) those levels decreased due to rise in the golf skill level, 3) blood fators and creatinine recovered quickly after exercise, however muscle damages did not recover even after 24hr, Therefore, both golf skill lev-el and practice volume should be considered to prevent muscle damage and fatigue during practice iron shot.

• Journal of Life Science
• /
• v.20 no.3
• /
• pp.403-410
• /
• 2010

In order to produce high-quality fermenting composts, a microorganism was isolated from the natural world. The bacterium has not only in high enzyme activities but also had good antimicrobial activities against phytopathogenic microorganisms. Its cultivating characteristics were then investigated. Bacterium KJ-9, which contains high CMCase, protease and chitinase activities and excellent antimicrobial activities against phytopathogenic microorganisms, was separated from leaf mold and identified as Bacillus licheniformis by two methods: Bergey's Manual of Systematic Bacteriology and API 50 CHL Carbohydrate Test Kit (Bio Merieux, France) using an ATB (Automated Identification) computer system (Bio Merieux, France). Optimal medium for cultivation of B. licheniformis was 2% soluble starch as a carbon source, 0.5% yeast extract as a nitrogen source and 0.05% $MgSO_4{\cdot}7H_2O$. Optimal growth conditions of pH, temperature and shake speed were pH 7.0, $50^{\circ}C$ and 180 rpm, respectively. Culture broth of B. licheniformis KJ-9 cultured for 36~60 hr was effective in fungicidal activities against plant pathogens including Botrytis cinerea, Corynespora cassicola, Fusarium oxysporum, and Rhizoctonia solani.

• Journal of Life Science
• /
• v.23 no.7
• /
• pp.926-932
• /
• 2013

Glutamine and serum are essential for cell survival and proliferation in vitro, yet the signaling pathways that sense glutamine and serum levels in endothelial cells remain uninvestigated. In this study, we examined the effects of glutamine deprivation and serum starvation on the fate of endothelial cells using a human umbilical vein endothelial cell (HUVEC) model. Our data indicated that glutamine deprivation and serum starvation trigger a progressive reduction in cell viability through apoptosis induction in HUVECs as determined by DAPI staining and flow cytometry analysis. Although the apoptotic effects were more predominant in the glutamine deprivation condition, both apoptotic actions were associated with an increase in the Bax/Bcl-2 (or Bcl-xL) ratio, down-regulation of the inhibitor of apoptosis protein (IAP) family proteins, activation of caspase activities, and concomitant degradation of poly (ADP-ribose) polymerases. Moreover, down-regulation of the expression of Bid or up-regulation of truncated Bid (tBid) were observed in cells grown under the same conditions, indicating that glutamine deprivation and serum starvation induce the apoptosis of HUVECs through a signaling cascade involving death-receptor-mediated extrinsic pathways, as well as mitochondria-mediated intrinsic caspase pathways. However, apoptosis was not induced in cells grown in glutamine- and serum-free media when compared with cells exposed to glutamine deprivation or serum starvation alone. Taken together, our data indicate that glutamine deprivation and serum starvation suppress cell viability without apoptosis induction in HUVECs.

• Korean Journal of Plant Resources
• /
• v.22 no.1
• /
• pp.102-110
• /
• 2009

This study examined the halophyte community and soil analysis according to habitat in representative 18 salt marshes of southern and western coasts of Korea from July 2006 to April 2008 and suggested basic materials for vegetational restoration of these aras. First, the survey area was classified into coastal and estuarine marshes. Then, the coastal marshes were classified into clay marsh, sand gravel marsh, and sand marsh, and the esturarine marshes, into salt swamp and estuary marsh. Major plant communities according to habitat pattern were Phragmites communis, Carex scabrifolia, and Suaeda japonica community in the clay marsh; Phragmites communis, Zoysia sinica, Carex scabrifolia, Salicornia herbacea, Artemisia fukudo, Suaeda martima community in the sand gravel marsh; Elymus mollis, Carex kobomugi, and Vitex rotundifolia community in the sand mars; Phragmites communis, Zoysia sinica, Suaeda martima, and Carex scabrifolia community in the salt swamp, and Suaeda japonica, Phragmites communis, Carex scabrifolia, and Suaeda asparagoides community in the estuary marsh. The soil environment of halophyte community area showed a difference to soil and halophyte community according to habitat characteristics of halophyte. Thus, to restore salt mashes in the coast area, it is advantageous for the stable settlement, germination, and growth of halophyte to grasp physical and physicochemical characteristics of habitat soil in the salt marshes, to select halophyte suitable to these habitat conditions, and to expand gradually in the natural vegetation area after transplantation.

• Korean journal of food and cookery science
• /
• v.21 no.3 s.87
• /
• pp.311-318
• /
• 2005

Echinacea, also blown as the purple coneflower, is a herbal medicine that has been used for centuries, customarily as a treatment for the common cold, coughs, bronchitis, upper respiratory infections, and some inflammatory conditions. We investigated the effects of methanol extracts of Echinacea angustifolia on the cytotoxicity against cancer cells $(HepG_2,\;3LL,\;HL60,\;L1210)$ and antioxidative activity. From the test results, each part of Echinaceashowed a cytotoxic effect against the cancer cell lines, and this cytotoxic effect increased with increasing sample concentration. At 1.0 mg/mL concentration the relative cytotoxic activities of the flower bud, leaf, stern and root parts were $90.5\%,\;52.7\%,\;37.1\%\;and\;19.2\%$, respectively, in $HepG_2$ cells, and $75.5\%,\;93.3\%,\;81.2\%,\;and\;75.1\%$ respectively, in HL60 cells, as evaluated by MTT assay. $IC_{50}(50\%\;inhibitory\;concentration)$ of the methanol extracts of the Echinacea flower bud was 0.214 mg/mL on /$HepG_2$ cells, and that of the Echinacea leaf and root was 0.166 mg/mL and 0.210 mg/mL, respectively, on HL60 cells. After /$HepG_2$ cells were incubated for 6 days at $37^{\circ}C$ with various concentrations of each part, the cell number increased while the inhibition rate on the /$HepG_2$ cell growth decreased. The antioxidative activities of the flower bud, leaf, stem and root parts were $59.0\%$ (0.75 mg/mL), $80.76\%$ (0.5 mg/mL), $95.5\%$ (0.25mg/mL) and $98.15\%$ (0.25 mg/mL), respectively, as evaluated by electron donating ability. These results indicated that Echinacea angustifolia has strong anticancer and antioxidative effects in vitro.

• Membrane Journal
• /
• v.25 no.2
• /
• pp.132-143
• /
• 2015

Water is an essential resource for humans, but fresh water becomes scarce due to population growth and contamination of limited resources. Membrane technology has been widely used for water treatment, and forward osmosis is a process which does not need high hydraulic pressure for the operation. However, there are needs for (1) development of novel draw solutes causing low internal concentration polarization and reverse salt flux for high water flux, and (2) development of economic recovery method of the draw solutes in the diluted draw solution. Previous researches on the draw solute include $NaHCO_3$ which can be regenerated by about $60^{\circ}C$ heating, sucrose which can make potable water without additional process, and magnetic nanoparticles which can be regenerated by external magnetic field. Using the principles of forward osmosis process, sea water desalination, wastewater treatment, refinement of proteins, energy generation using pressure retarded osmosis process, preparation of diluted fertilizer, and growing algae for biofuel can be conducted. This paper summarizes characteristics of ideal draw solutes, recovery method of the draw solutes, and various application examples.

• Korean Journal of Microbiology
• /
• v.36 no.4
• /
• pp.279-284
• /
• 2000

Simultaneous reduction of Cr(VI) and degradation of phenol was observed in batch and bench-scale continuous stirred tank reactors using Rhodococcus sp. CP01 isolated from leachate. The strain CP01, which was capable of utilizing phenol as a sole source of carbon and energy, completely reduced added hexavalent chromium (0.25 mM) to its trivalent form during 60 hr batch assay under optimal conditions (pH 7.0 and 1,000 mg/L of phenol concentration). The rates of Cr(VI) reduction and phenol degradation were estimated as 4.17 $\mu$M Cr(VI) and 38.4 mg phenol.$L^{-1}{\cdot}hr^{-1}$, respectively. The continuous culture experiment was conducted for 46 days using synthetic feed containing different levels of chromate (0.0625 to 0.25 mM) and phenol(1,000 to 4,000 mg/L). With a hydraulic retention time of 100 hr, Cr(VI) reduction efficiency was mostly 100% for influent Cr(VI) and phenol concentrations of 0.125 mM and 3,000 mg/L, respectively. During quasi-steady-state operation, specific rate of Cr(VI) reduction was calculated as 0.34 mg Cr(VI).g $protein^{-1}{\cdot}hr^{-1}$ which was comparable to reported values obtained by using glucose as growth substrate. The results suggest the potential application of biological treatment for detoxification of wastewater contaminated simultaneously with Cr(VI) and pheonol.