• The Journal of the Convergence on Culture Technology
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• v.9 no.3
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• pp.601-606
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• 2023

The edible sweetener aspartame is formed from the synthesis of asparagine, one of the amino acids, and phenylalanine. It is a protein ingredient that produces sweetness 200 times higher than sucrose, and is used as a diet product because it is a substance that can replace sugar. Although the effects on animals and humans have been well studied, no studies have been conducted on plant metabolism. In this study, the effect of aspartame metabolism was tested using germinated onion, bean sprouts, and Kalanchoe. The three types of plants with germinated roots showed rapid growth in the early stage of treatment with 1mM aspartame, and showed a nutrient supply effect due to the effect of amino acids, which are constituents. However, when treated for 4 weeks, symptoms similar to lateral roots appear in the form of lignification in onions, the effect of quickly withering is seen in bean sprouts, and senescence of roots appears in 12-week-old Kalanchoe. All of them show accelerated aging after the growth phase. This shows that, among the two amino acids, asparagine is related to auxin generation that induces rapid growth, and it is thought to be the result of lignification due to the effect of phenylalanine.

• Food Science and Preservation
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• v.13 no.1
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• pp.30-36
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• 2006

Milk protein-gum conjugates were prepared by Maillard reaction and added to dough to investigate the possibile use of them as anti-staling agents in bread Four different types of conjugates were added to dough, i.e., $casein-\kappa-carrageenan$ (CK), casein-sodium alginate (CA), $whey-\kappa-carrgeenan$(WK) and whey-sodium alginate (WA). Their addition to flour increased the gelatinization temperature, water absorption and development time of the dough. Extensogram showed the increased resistance to extension of the doughs resulting from the addition of the conjugates. Moisture content of the breads decreased during storage at $5^{\circ}C$ for 4 days. The breads added with conjugates had lower extents of the decreases than non-treated degrees and maintained higher moisture content than non-treated bread after 3 freeze-thaw cycles. The storage degrees at $5^{\circ}C$ for 4 days affected the increased bread hardness, but, addition of WA conjugate decreased extents of the increases. Therefore, milk protein-gum conjugates, especially WA conjugate, contributed to retarding staling of breads

• Journal of the Society of Cosmetic Scientists of Korea
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• v.22 no.1
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• pp.27-39
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• 1996

Recently, in vitro stratum curneum model was a useful tool to evaluate the skin condition such as tranespidermal water loss, skin hydration and etc.. In this study to evaluate the alteration of SC with aging in hairless mouse, we measured TEWL using in vitro SC model, SC lipid, and outer corneocytes area. Although the total SC lipid was rich about 30% in 8 week old mouse compared with that of 82 week old mouse, the TEWL values were higher in the former than that of the latter. The outer corneocytes area was 559 $\pm$ 65 $mu extrm{m}$2 in 8 week old mouse and 755 $\pm$ 56 ${\mu}{\textrm}{m}$2 in 82 week old mouse. So the barrier function was reinforced with aging. This result suggested that the reinforced barrier function is one of the defense systems against the outer enviornment and the decreased skin function with aging.

• Development and Reproduction
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• v.11 no.1
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• pp.13-20
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• 2007

In all female mammals, reproductive system is one of the first biological systems to show age-related decline. Female mammals in reproductive aging, though the phenomena is somewhat species-specific, start to show declining fertility and changes of numerous physiological functions. This review will present a current information on the aging of the female reproductive hormonal axis and introduce three useful rodent models for studying this field. Middle age($8{\sim}12$ months old) in female rats and mice is comparable to the stage prior to the entry of menopause in human. In this period pulsatile and surge GnRH secretion from hypothalamus gradually attenuated, then reduced pulsatile and surge LH secretion is followed consequently. This age-related defects in GnRH-LH neuroendocrine axis seem to be highly correlated with the defects in brain signals which modulate the activities of GnRH neuron. Many researchers support the idea which the age-related hypothalamic defects are the main cause of reproductive aging, but some ovarian factors such as inhibin response also could contribute to the induction of reproductive senescence. Some rodent models are quite valuable in studying the reproductive aging. The follitropin receptor knockout(FORKO) mice, both of null and haploinsufficient state, could produce depletion of oocyte/follicle with age. Dioxin/aryl hydrocarbon receptor(AhR) knockout mice also show severe ovarian defects and poor reproductive success early in their life compared to the age-matched normal mice. Further studies on the reproductive aging will be a great help to evaluate the benefits and risks of hormone replacement therapy(HRT) and to improve the safety of HRT.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.12
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• pp.8637-8642
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• 2015

Typical aging for the rubber using the current military adhesive combat boots was spread with a regular aging caused by heat stress. In this study, the aging test of the rubber for combat boots was carried out and the reaction rate constant, k was calculated at aging temperature $60^{\circ}C$, $80^{\circ}C$ and $100^{\circ}C$, using the Arrhenius equation. The lifetime limit was assumed that the tensile strength of the product is reduced to 30%, the elongation is reduced to 50% and abrasion resistance ratio is 380%. ln($P/P_0$) and the lifetime was predicted with the consideration of the activation energy constant. According to the above, the lifetime of the rubber for combat boots with influenced by aging temperature was predicted. As the result, the estimate lifetime at $20^{\circ}C$ was confirmed more than 10 years.

• Journal of the Korean Society of Propulsion Engineers
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• v.24 no.2
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• pp.1-13
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• 2020

The characterization of aging of the pyrotechnic device is conducted thermally, chemically, and spectroscopically. The device is comprised of two parts: (i) igniter composed of Zr and (ii) pyrotechnic delay composed of ZrNi alloy. The thermally induced chemical reaction is identified through Differential Scanning Calorimetry (DSC) and Thermogravimetry Analysis (TGA). The peak deconvolution of the themo-chemical data is used to estimate the enthalpy change of each metallic fuel component. Laser Induced Breakdown Spectroscopy (LIBS) and X-ray Photoelectron Spectroscopy (XPS) are used for chemical species analysis. The decomposition of oxidants by moisture significantly affected the fuel aging, and the formation of oxide film and metal oxide on the fuel surface gave rise to the thermal energy decrease.

• Korean Journal of Food Science and Technology
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• v.29 no.3
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• pp.464-469
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• 1997

Rapid visco-analyzer (RVA) and differential scanning calorimetry (DSC) were used to study the effect of rice bran dietary fiber extract on gelatinization and retrogradation of wheat flour. The addition of rice bran dietary fiber extracts from various heat treated bran into wheat flour caused to increase the pasting temperature, peak viscosity and final viscosity of RVA measurements. For gelatinization measured with DSC, mixtures of wheat flour and rice bran dietary fiber extract had slightly higher To (onset temperature) and Tp (peak temperature) values than those of control (wheat flour), and wheat flour/defatted rice bran dietary fiber extract mixture had the lowest enthalpy value. In comparison with gelatinization, the retrogradation endotherm of mixtures stored at $4^{\circ}C$ up to 4 weeks occurred at about $20^{\circ}C$ lower temperatures than gelatinization endotherm with broader shape and well-defined thermograms with storage time. The retrogradation of wheat flour was retarded greatly by addition of rice bran dietary fiber extract, and there was no big difference between 5% and 10% additions.

• Journal of the Korean Society of Food Science and Nutrition
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• v.32 no.2
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• pp.175-180
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• 2003

Effect of the addition of maltitol to Korean rice cake (Karedduk) on its retrogradation was examined. Degree of retrogradation was also examined in terms of recrystallinity of starch and color change with a differential scanning calorimeter. As a result, retrogradation was suppressed by the increasing addition of maltitol. In particular, enthalpy showed a tendency to decrease at $25^{\circ}C$ rather than at 4$^{\circ}C$ during 4 days. In the gelatinization properties using DSC, onset temperature (To) was shown to increase slightly according to storage time. Maximum peak temperature (Tp) was shown to decrease by the addition of maltitol during 4 days. Melting enthalpy was decreased at $25^{\circ}C$ and 4$^{\circ}C$ by the addition of maltitol. The analysis X-ray diffraction also revealed that retrogradation of the Korean rice cake was suppressed by the addition of maltitol because crystalline region did not appear. The addition of maltitol into the Korean rice cake was found to result in an increase of its qualify or color stability.

• Microbiology and Biotechnology Letters
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• v.35 no.4
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• pp.316-324
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• 2007

We studied the effects of genistein obtained from glycolysis of genistin, a kind of phytoestrogen present in soybeans, on cell proliferation and type I pN collagen synthesis in normal human dermal fibroblasts(NHDF). Cell proliferation was increased significantly with genistein treatment at 54-year aged NHDF. Genistein increased cell proliferation more strongly in cells form old doner than young doner. The senescence-associated ${\beta}$-galatosidase activity was decreased in NHDF from 77-year old doner with genistein treatment. Type I pN collagen synthesis was increased with genistein treatement in UVA treated and non-treated NHDF. The increasement of collagen synthesis was more effective in aged cells than young cells. Type I pN collagen synthesis was also increased with genistein treatment in collagen matrix culture with NHDF from sun-exposed and non-exposed skin from 54-year old doner. Genistein treatment inhibited MMP-1 synthesis in old NHDF but not in young NHDF. In conclusion, genistein may be a useful agent for preventing intrinsic aging as well as photoaging.

• Elastomers and Composites
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• v.47 no.1
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• pp.9-17
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• 2012

Herein, life time prediction based on the deterioration of physical properties of chloroprene rubber (CR)aged by heat and seawater was performed. CR samples were experienced an accelerated test at $80^{\circ}C$, $100^{\circ}C$, $120^{\circ}C$ for heat aging, and $40^{\circ}C$, $60^{\circ}C$, $80^{\circ}C$ for seawater aging for 20,000 hrs. The change in tensile strength, maximum elongation,hardness was measured. As a result, the decrease in elongation was a major factor causing failure. The life time estimated using an Arrhenius model was 125 years at $23^{\circ}C$ for thermal aging and 9 years at $23^{\circ}C$ for seawater aging. SEM and elemental analysis reveal that cracks were generated and the content of oxygen was increased for CR agined by seawater. FT-IR spectrum shows the new C-O and C = O bonds were generated by the chemical reaction with seawater. Also, the glass transtion temperature was increased and the thermal decomposition was decreased by seawater aging.