• Journal of the Korean Society of Food Science and Nutrition
• /
• v.37 no.12
• /
• pp.1560-1567
• /
• 2008

This study was designed to evaluate the effect of green tea products (GTP) on bone metabolism marker in ovariectomized (OVX) rats fed high cholesterol diet. Forty Sprague-Dawley female rats, 10 weeks of age ($279{\pm}2g$), were divided into 4 groups and fed on the experimental diets for 6 weeks: sham operated control (Sham-C) and OVX-control (OVX-C) groups treated high cholesterol diet. OVX-GTP 5% (OVX-G5) and OVX-GTP 20% (OVX-G20) groups were treated with high cholesterol diet containing 5% GTP and 20% GTP, respectively. Food efficient ratio was significantly (p<0.05) lower in OVX-G20 than in the other OVX groups. Bone mineral density of femur was not significantly different among the experimental groups in the order of Sham-C>OVX-G5 and OVX-G20>OVX-C. Alkaline phosphatase activities on serum was lower in the GTP supplement groups than in the OVX-C. Estradiol levels of serum were higher in the GTP supplement groups than in the OVX-C. Osteocalcin levels of serum was the lowest in the OVX-G20. Deoxypyridinoline crosslink values of urine, indicator of bone absorption, was the lowest in the OVX-G20 group. The GTP supplemented groups had a lower bone resorption ratio than in the OVX-C group. From the above results, these findings suggest the possibility of using GTP as a functional food materials related to bone metabolism in menopause.

• Journal of Korean Society of Forest Science
• /
• v.106 no.3
• /
• pp.288-299
• /
• 2017

This study was conducted to find out the influence of drought stress on physiological responses of Synurus deltoides. Drought stress was induced by withholding water for 25 days. Leaf water potentials were decreased of both predawn (${\Psi}_{pd}$) and mid-day (${\Psi}_{mid}$) with increasing drought stress, but water saturation dificit (WSD) was 7 times increased. ${\Psi}_{pd}-{\Psi}_{mid}$ showed the significant difference of 0.22~0.18 MPa in stressed before 10 days, and nonsignificant as treatment time became longer. A strong reduction of stomatal conductance ($gH_2O$) and stomatal transpiration rate (E) were observed after 15 days of drought stress Significant reductions of net apparent quantum yield (${\Phi}$) and maximum photosynthesis rate ($Pn_{max}$) were observed after 20 days of drought stress; However, water use efficiency (WUE) was shown the opposite trend. This implies that decrease of photosynthesis rate may be due to an inability to regulate water and $CO_2$ exchanged through the stomata. From JIP analysis, flux ratios (${\Psi}_O$ and ${\Phi}_{EO}$) and performance index on absorption basis ($PI_{ABS}$) were dramatically decreased withholding water after 15 days, which reflects the relative reduction of photosystem II activity. The leaf of S. deltoides showed osmotic adjustment of -0.35 MPa at full turgor and -0.40 MPa at zero turgor, and also cell-wall elastic adjustment of 9.4 MPa, indicating that S. deltoides tolerate drought stress through osmotic adjustment and cell-wall elastic adjustment. The degree of change in water relations parameters such as Vo/DW, Vt/DW decreased with increasing drought stress. This result showed that S. deltoides was exhibited a strong reduction of photosynthetic activity to approximately -0.93 MPa of predawn leaf water potential, and both of osmotic adjustment and cell-wall elastic adjustment in drought stress condition appears to be an important adaptation for restoration in this species.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.19 no.1
• /
• pp.94-131
• /
• 2007

A review on the papers published in the Korean Journal of Air-Conditioning and Refrigerating Engineering in 2004 and 2005 has been done. Focus has been put on current status of research in the aspect of heating, cooling, air-conditioning, ventilation, sanitation and building environment. The conclusions are as follows. (1) Most of fundamental studies on fluid flow were related with heat transportation of facilities. Drop formation and rivulet flow on solid surfaces were interesting topics related with condensation augmentation. Research on micro environment considering flow, heat, humidity was also interesting for comfortable living environment. It can be extended considering biological aspects. Development of fans and blowers of high performance and low noise were continuing topics. Well developed CFD and flow visualization(PIV, PTV and LDV methods) technologies were widely applied for developing facilities and their systems. (2) The research trends of the previous two yews are surveyed as groups of natural convection, forced convection, electronic cooling, heat transfer enhancement, frosting and defrosting, thermal properties, etc. New research topics introduced include natural convection heat transfer enhancement using nanofluid, supercritical cooling performance or oil miscibility of $CO_2$, enthalpy heat exchanger for heat recovery, heat transfer enhancement in a plate heat exchanger using fluid resonance. (3) The literature for the last two years($2004{\sim}2005$) is reviewed in the areas of heat pump, ice and water storage, cycle analysis and reused energy including geothermal, solar and unused energy). The research on cycle analysis and experiments for $CO_2$ was extensively carried out to replace the Ozone depleting and global warming refrigerants such as HFC and HCFC refrigerants. From the year of 2005, the Gas Engine Heat Pump(GHP) has been paid attention from the viewpoint of the gas cooling application. The heat pipe was focused on the performance improvement by the parametric analysis and the heat recovery applications. The storage systems were studied on the performance enhancement of the storage tank and cost analysis for heating and cooling applications. In the area of unused energy, the hybrid systems were extensively introduced and the life cycle cost analysis(LCCA) for the unused energy systems was also intensively carried out. (4) Recent studies of various refrigeration and air-conditioning systems have focused on the system performance and efficiency enhancement. Heat transfer characteristics during evaporation and condensation are investigated for several tube shapes and of alternative refrigerants including carbon dioxide. Efficiency of various compressors and expansion devices are also dealt with for better modeling and, in particular, performance improvement. Thermoelectric module and cooling systems are analyzed theoretically and experimentally. (5) According to the review of recent studies on ventilation systems, an appropriate ventilation systems including machenical and natural are required to satisfied the level of IAQ. Also, an recent studies on air-conditioning and absorption refrigeration systems, it has mainly focused on distribution and dehumidification of indoor air to improve the performance were carried out. (6) Based on a review of recent studies on indoor environment and building service systems, it is noticed that research issues have mainly focused on optimal thermal comfort, improvement of indoor air Quality and many innovative systems such as air-barrier type perimeter-less system with UFAC, radiant floor heating and cooling system and etc. New approaches are highlighted for improving indoor environmental condition as well as minimizing energy consumption, various activities of building control and operation strategy and energy performance analysis for economic evaluation.

• Journal of Preventive Medicine and Public Health
• /
• v.31 no.3 s.62
• /
• pp.449-459
• /
• 1998

This study was started to find out if plasma malondialdehyde(MDA), $\alpha-tocopherol$ and erythrocyte superoxide dismutase(SOD) activity could be markers of biological activity resulting from exposed to lead in workers. Blood samples were randomly obtained from lead-exposed workers(n=29), $CO_2$, welders(n=60) and office workers(n=60). We used whole blood to analyse blood lead with atomic absorption spectrophotometer. Superoxide dismutase activity in erythrocyte was measured with spetrophotometer. MDA and $\alpha-tocopherol$ in plasma were measured with high performance liquid chromatography. Lead-exposed workers was significantly high in blood lead concentration$(29.37{\mu}g/d\ell)$ compared with welders$(6.42{\mu}g/d\ell)$ and office workers$(5.01{\mu}g/d\ell)$. The level of plasma MDA was significantly higher in the lead-exposed workers($1.87{\mu}mol/g$ cholesterol) than the welders($1.41{\mu}mol/g$ cholesterol) and office workers($1.41{\mu}mol/g$ cholesterol). Erythrocyte SOD activity in lead-exposed workers(56.80 U/g Hb) was significantly increased than those of welders(37.63 U/g Hb) and office workers(20.47 U/g Hb). The plasma $\alpha-tocopherol$ level of lead-exposed workers($4.93{\mu}g/g$ cholesterol) was statistically different from welders($4.25{\mu}g/g$ cholesterol) and office workers$4.28{\mu}g/g$ cholesterol). Neither age nor smoking was related to SOD or MDA level. Blood lead was significantly correlated with erythrocyte SOD activity(r=0.405), plasma MDA(r=0.296) and $\alpha-tocopherol$ (r=0.207). Plasma MDA was also significantly correlated with SOD (r=0.217). In multiple regression analysis, the change of MDA and SOD activity level related to the blood lead concentration. These results suggested that the increase of plasma MDA and erythrocyte SOD activity in lead-exposed workers had a close relationship with the oxidative stress induced by lead.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.19 no.6
• /
• pp.318-323
• /
• 2009

The lightweight aggregates made of bottom ash (70 wt%) and dredged soil (30 wt%) were prepared to investigate the property differences at various sintering atmospheres. The green aggregates were sintered at $1150^{\circ}C$ and $1200^{\circ}C$ with oxidized, neutralized and reduced atmospheres. The aggregates sintered with oxidized atmosphere showed a clear border between shell and black core area. However, the aggregates sintered with a reduced atmosphere showed only black core area in the entire cross-section of the aggregates. The black core area of the aggregates sintered with a neutralized atmosphere increased with increasing $N_2$ gas flow rates. It was determined that the sintering atmosphere was similar to that of rotary kiln when the CO gas flow was 100 cc/min to make a reduced atmosphere in tube furnace. The water absorption rates of both aggregates from tube furnace with reduced atmosphere and rotary kiln were very similar to each other.

• Journal of the Korean GEO-environmental Society
• /
• v.18 no.8
• /
• pp.23-32
• /
• 2017

For exposed slopes, the weathering degree over time has a major effect on the engineering properties of rocks and the slope stability. Rocks are gradually changed by weathering into soil over time, and the resulting physical, chemical and mechanical changes of rocks affect the engineering stability of the slope. However, there are not many ways to objectively evaluate the weathering degree of a slope. In this study, therefore, to investigate the weathering characteristics of rocks, granite, gneiss and shale distributed in the Chungbuk region were sampled by weathering stage and changes in their component minerals and tissues were investigated. Furthermore, artificial weathering was induced using the freezing and thawing test and quantitatively investigated through porosity and absorption rate. In addition, the changes of microcracks due to artificial weathering were evaluated through box fractal dimension ($D_B$). Through mineralogical study the phase change of constituting minerals, the growth of secondary minerals, the development of micro-cracks and the fabric changes due to weathering were observed. The mineralogical, chemical and engineering evaluations of the weathering degree through the experimental results in this study are expected to be useful for analyzing the weathering characteristics and causes by rock type and for proposing a methodology to evaluate the degradation of physical properties comparatively and quantitatively.

• Asian-Australasian Journal of Animal Sciences
• /
• v.19 no.8
• /
• pp.1206-1211
• /
• 2006

The effects of taurine supplementation on growth performance, serum and liver concentrations of lipid, fatty acid composition and lipid peroxidation in the livers of broilers under chronic heat exposure conditions were investigated. The chicks with a similar body weight were equally assigned to one of three controlled-environment chambers. The brolier chicks, which were kept at $34^{\circ}C$ were fed either with a control diet or the control diet supplemented with 0.8% taurine, whereas broiler chicks kept at $22^{\circ}C$ were fed a control diet. Both of the BW and BW gains of broilers maintained at a temperature of $34^{\circ}C$ were significantly lower than those of the control group, which was maintained at a temperature of $22^{\circ}C$ (p<0.05). However, taurine addition in the diet of birds submitted to heat stress siginficantly improved BW gain (p<0.05). The feed intake of chicks declined with increases in temperature. The relative liver and gall bladder weights of chicks fed the control diet and maintained at $34^{\circ}C$ were significantly lower than those measured in the control birds (p<0.05). However, dietary taurine was found to compensate for these reductions in liver and gall bladder weights. Relative weights of abdominal fat did not differ significantly among the three groups. Serum triglyceride concentrations were significantly lower in the chicks fed the control diet and maintained at $34^{\circ}C$ compare to those measured in the chicks fed the control diet at $22^{\circ}C$ (p<0.05). Heat stress resulted in a significant reduction in total lipid and triglyceride levels, but also increased the levels of total cholesterol in the liver (p<0.05). However, dietary taurine supplementation under the heat stress condition resulted in the recovery, to control levels, of serum triglyceride concentrations, as well as the amounts of total lipids, triglycerides, and cholesterol in the liver. The livers of chicks fed on taurine diets at $34^{\circ}C$ showed significantly higher proportions of C14:0, C16:1, C18:1, C18:2, and 20:3, and lower C18:0 and C20:4 proportions than those of chicks fed on control diets at the same temperature (p<0.05). The total levels of saturated fatty acids decreased, but monounsaturated fatty acids and unsaturated fatty acid levels increased in chicks fed the taurine diet, as compared to chicks fed the control diet at $34^{\circ}C$ (p<0.05). Peroxidizability indices were significantly lower in the heat-exposed chicks fed the taurine diet than in the non-taurine heat-exposed groups (p<0.05). In conclusion, dietary taurine results in an increase in the growth performances of chicks under heat stress conditions via improvements in lipid absorption and metabolism, as well as an induced reduction in lipid peroxidation.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
• /
• 2006.06b
• /
• pp.231-237
• /
• 2006

Grease barrier food containers are commonly used for packaging of fast food, cooked food, and food in general. Greaseproofing is also used for certificate paper and label paper etc. Different pulp raw materials, due to their different fiber morphology and chemical compositions, produce papers of varying characteristics. We used optical photomicroscopy and fiber analysis data to evaluate fiber morphology and traits under various beating conditions in order to understand which pulp raw materials produced superior greaseproofing property when a fluorinated greaseproofing agent was added internally. The experiment studied 9 species of pulps, including 2 softwood (northern pine and radiata pine) bleached kraft pulps which were beaten to 550 and 350 mL CSF, respectively; 3 hardwoods (eucalypts, acacia, mixed Indonesian hardwoods) bleached kraft pulps which were beaten to 450 and 250 mL CSF, respectively; and nonwood fibers of reed, bagasse, and abaca. A fluorinated greaseproofing chemical at 0.12% dosage with respect to dry pulp was added to each pulp preparation and formed handsheets. A total of 67 sets of handsheets were prepared, and their basis weights, thickness, bulks, opacities, wet opacities, air resistance, water absorption and degrees of greaseproofing were measured for an overall evaluation of pulp and freeness on greaseproofing papers. The experimental fiber length, coarseness and distribution characteristics and the greaseproofing results suggest that softwood pulps (radiate pine > northern pine) were superior to hardwood pulps (eucalypts > acacia > mixed Indonesian hardwoods). The unbeaten pulps gave papers with high porosities and nearly devoid of greaseproofing property. Greaseproofing is proportional to air resistance. Among the nonwood fibers, bagasse had the best greaseproofing property, followed by reed and abaca was the poorest. With regards to waterproofing property, hardwood pulps (mixed Indonesian hardwoods > acacia > eucalypts) were better than softwood pulps (northern pine > radiate pine). Among the Nonwood fibers, reed had the highest waterproofing property, and it was followed by abaca, while bagasse had the poorest waterproofing characteristic. In summary, bleached kraft northern pine, eucalypts and reed pulps were best suited for making greaseproofing papers, Freeness of the pulps should be kept at $200{\sim}280mL$ CSF for optimal performance.

• Journal of Technology Innovation
• /
• v.19 no.2
• /
• pp.153-184
• /
• 2011

This paper investigates what kind of technological partner firms want to cooperate with in terms of partner location. Two geographical factors are considered. One is geographical proximity, given the tradeoff between the effectiveness of knowledge spillovers in proximity and diverse knowledge absorption from geographically distant partners. The other is how many other firms are co-located with potential partners because it is known that clustering regions can create more technological outputs. Analysis on 2008 Korea Innovation Survey data finds that partner proximity is the single most important factor in choosing a cooperation partner. While firms that are located in a region crowded with related industries prefer proximate partners, others that are surrounded by unrelated industries are more likely to cooperate with distant partners. The findings suggest that geographical proximity matters in partner selection because it not only stimulates knowledge spillovers but also reduces costs involving R&D cooperation such as monitoring costs and information costs. Moreover, firms take into consideration both the benefits and risks of clustering regions. If there are so many unrelated firms that they create agglomeration diseconomies such as congestion costs and unintentional knowledge leakages, firms are more likely to try to find their cooperation partners in other regions.

• The Korean Journal of Mycology
• /
• v.28 no.2
• /
• pp.67-72
• /
• 2000

The purpose of this study was to investigate the change of water content in mushroom substrate, paddy straw, and the mycelial growth of oyster mushroom by various soaking time. The water content of paddy straw was gradually increased as the soaking time was getting longer. These experiments also showed that the water content in the upper part of paddy straw was less than that of the low part. The mycelial growth was the good between 4 and 12 hours soaking treatment, showing faster growth and higher density in the lower part than the upper part. However we could not found any significant variation among 5 strains of oyster mushroom in the effects of the various soaking times and soaking part. The pH of the lower part substrates had a low pH compared with that of the upper part. When pathogens and mushroom mycelia were co-inoculated on paddy straw under various soaking conditions, the mushroom mycelial growth showed fast and high density according to the increase of the soaking time. The experiment related to water transport reveals that it is not easy to move into upper part, but only soaked part by adding water is available to absorb enough water. Old straw was much better than the straw new this year one for water absorption, mycelial growth and mycelial density.