• Journal of Physiology & Pathology in Korean Medicine
• /
• v.24 no.4
• /
• pp.646-652
• /
• 2010

Gambejaeseup-tang (GBJST) have recently been used as an anti-obesity herbal medicine but their effect and mechanism of action have not been studied. We modified ingredients of GBJST based on the previous experiments about exploring herbs to suppress triglyceride accumulation in 3T3-L1 adipocytes. We investigated the effects of modified GBJST on energy, glucose and lipid homeostasis using female rats with diet-induced obesity and their action mechanism was also determined. Rats fed a high-fat diet (HFD) were divided into 3 groups: rats in each group received 0.2 or 2 g water extracts of modified GBJST (L-GBJST or H-GBJST) or 2 g cellulose per kg body weight (a negative control) on a daily basis. A further group was fed a low-fat diet (LFD) as a positive control. We found that modified GBJST dose-dependently decreased body weight and mesenteric and retroperitoneal fat more than the control. This decrease was due to the reduction in energy intake and the increase of energy expenditure. HFD increased fat oxidation more than LFD and modified GBJST further increased fat oxidation as a major energy source more than the control in a dose-dependent manner. In addition, H-GBJST improved glucose tolerance without changing serum insulin levels during an oral glucose tolerance test. H-GBJST also suppressed the increase of serum total and LDL cholesterol and triglyceride levels by HFD. In conclusion, modified GBJST have a good anti-obesity effect by decreasing energy intake and increasing energy expenditure mainly as fat in female rats with diet-induced obesity. It also improves glucose tolerance and lipid metabolism.

• KIEAE Journal
• /
• v.10 no.5
• /
• pp.3-12
• /
• 2010

Sustainable design is getting to be controversial issue in all industries over the world particularly, in architecture as the amount of energy usage in architecture occupies 40%. Therefore, it is essential to make the standard for the sustainable design. In order to construct the sustainable design, firstly it should be considered that sustainable design elements based on natural resources to increase building energy efficiency is established and classified. The method of sustainable design divides into passive design and active design. Passive design method should be examined with active one simultaneously for more efficient usage of energy. Next, the study is followed how the sustainable design elements is adopted in buildings through the comparison of cases study of domestic and oversea. The result of case study shows similar adoption of sustainable design elements between oversea and domestic. However, the difference is shown in the building orientation and shape and the window size and position in Solar energy as well as high performance structure in Heat energy. These elements are the most significant elements in order to reduce energy load. In oversea, sustainable design is generated by architects, a client, and consultants based on the close cooperation in the beginning of early design phase before deciding building shape and envelope while in the domestic field adoption for sustainable design is conducted after deciding building shape and material. In order to design sustainable architecture more study is necessary in early stage for Zero Carbon and reducing building energy load through relation with specialists, a client and architects.

• Journal of the Korean Institute of Gas
• /
• v.17 no.5
• /
• pp.1-7
• /
• 2013

In this study, simulation work of HCNG refueling system was performed. The hydrogen was produced from steam reforming process by natural gas. The conversion of natural gas is increased as SCR is increased. but it was no significant difference more than 3 of SCR and fuel throughput is increased as GHSV is increased. Both conversion and fuel throughput levels was optimized when the $1700h^{-1}$ of GHSV. CNG was compressed from low pressure natural gas. For the mixing of $H_2$ and CNG is mixed with the high pressure conditions such as 400bar of $H_2$ and 250bar of natural gas. Single-stage compression was required more power than multi stage. So, multi stage compression was suggested for high pressure compression. We calculated the intermediate pressure to minimize total required power of compressors. The intermediate pressure for $H_2$ and natural gas were derived at 61 and 65 bar, respectively.

• Journal of computational fluids engineering
• /
• v.18 no.4
• /
• pp.25-34
• /
• 2013

A numerical study of a laminar natural convection of the CuO-water nanofluid in a square cavity using the Buongiorno's nonhomogeneous model is presented. All the governing equations including the volume fraction equation are discretized on a cell-centered, non-uniform grid employing the finite-volume method with a primitive variable formulation. Calculations are performed over a range of Rayleigh numbers and volume fractions of the nanopartile. From the computed results, it is shown that both the homogeneous and nonhomogeneous models predict the deterioration of the natural convection heat transfer well with an increase of the volume fraction of nanoparticle at the same Rayleigh number, which was observed in the previous experimental studies. It is also shown that the differences in the computed results of the average Nusselt number at the wall between the homogeneous and nonhomogeneous models are very small, and this indicates that the slip mechanism of the Brown diffusion and thermophoresis effects are negligible in the laminar natural convection of the nanofluid. The degradation of the heat transfer with an increase of the volume fraction of the nanoparticle in the natural convection of nanofluid is due to the increase of the viscosity and the decrease of the thermal expansion coefficient and the specific heat. It is clarified in the present study that the previous controversies between the numerical and experimental studies are owing to the different definitions of the Nusselt number.

• Korean Chemical Engineering Research
• /
• v.47 no.1
• /
• pp.65-71
• /
• 2009

In this study, performance and economic analysis of natural gas/syngas fueled 100 MWth chemical-looping combustion (CLC) combined cycle plant were performed. Net efficiency of both cases was 53~54%, corresponding to previous research. We used Chemical Engineering Plant Cost Index and Guthrie method to evaluate plant cost. For syngas fueled CLC combined cycle plant, the plant cost was higher since lower heating value(LHV) of syngas was lower than that of natural gas and cost of electricity(COE) was also higher since the cost of syngas was higher than that of natural gas. By sensitivity analysis, it was shown that the cost of syngas should be less than 5.3 $/GJ in order to make COE lower than 5.8 ¢/kWh which was COE of natural gas fueled CLC combined cycle plant.

• Polymer(Korea)
• /
• v.35 no.1
• /
• pp.72-76
• /
• 2011

The physical properties of crosslinked poly(vinyl alcohol)(PVA) by natural dyes as crosslinking agents were investigated and a comparison was made with chemically crosslinked PVA by Polycup 172. It was found that natural anthocyanin and crocin made possible to crosslink PVA physically through the hydrogen bonding of OH in both PVA and natural dyes in the present with NaCl as a catalyst. The water swellability dramatically decreased and the physical crosslinking led to decreasing of crystallinity of PVA. The lowering of thermal stability was noticed in the physically crosslinked PVA compared to chemically crosslinked PVA due to its lower crosslink density. However even natural dyes have polysaccharides in their chain, their thermal stability was higher than uncrosslinked PVA.

• Journal of Environmental Science International
• /
• v.24 no.6
• /
• pp.819-826
• /
• 2015

This study measured temperatures and albedos of urban surfaces for different colors and materials during summer, and calculated the energy budget over different urban surfaces to find out the thermal performance affecting the heat built-up. The study selected six surface colors and 13 materials common in urban landscape. Their surface temperatures (Ts) and albedos were measured at a given time interval in the daytime from June to August. Average Ts over summer season for asphalt-colored brick was $4.0^{\circ}C$ higher than that for light red-colored one and $9.7^{\circ}C$ higher than that for white-colored one. The Ts for artificial surface materials of asphalt paving, brown brick wall, and green concrete wall was $6.0^{\circ}C$ higher than that for natural and semi-natural ones of grass, grassy block, and planted concrete wall. There was the greatest difference of $16.3^{\circ}C$ at midafternoon in the Ts between asphalt paving and planted concrete wall. Average albedo over summer season of surface materials ranged from 0.08 for asphalt paving to 0.67 for white concrete wall. This difference in the albedo was associated with a maximum of $15.7^{\circ}C$ difference at midafternoon in the Ts. Increasing the albedo by 0.1 (from 0.22 to 0.32) reduced the Ts by about $1.3^{\circ}C$. Average storage heat at midday by natural and semi-natural surfaces of grass and grassy block was about 10% lower than that by artificial ones of asphalt, light-red brick, and concrete. Reflected radiation, which ultimately contributes to heating the urban atmosphere, was 3.7 times greater for light-red brick and concrete surfaces than for asphalt surface. Thus, surfaces with in-between tone and color are more effective than dark- or white-colored ones, and natural or semi-natural surfaces are much greater than artificial ones in improving the urban thermal environment. This study provides new information on correlation between Ts and air temperature, relationship between albedo and Ts, and the energy budget.

• Proceedings of the SAREK Conference
• /
• 2006.06a
• /
• pp.387-392
• /
• 2006

The recent on indoor air problem has led to many studies on the methods and effects of ventilation for better indoor air quality. Although natural ventilation is the most effective and energy-saving method in residental housings, the small size of openable window has been a problem in high-rise residential buildings to ventilate only through natural ventilation. Consequently, the installation of mechanical ventilation system has been a requirement in residential buildings, and has caused other problems such as increase of energy consumption and SBS. Hybrid ventilation which uses forces of both natural and mechanical power has been introduced to solve the problem of increase in energy consumption with natural ventilation. In this paper, two types of hybrid ventilation systems in residential building were introduced. One type was with natural ventilation through vent grille in the window, and another type was with natural ventilation through ceiling duct while both types used mechanical ventilation system with the outlets. The indoor temperature distribution and pollution density distribution in summer while operating the ceiling air conditioner were analyzed through CFD simulation. In this paper, the optimal location of diffusers to achieve thermal comfort would be proposed.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
• /
• 2006.05a
• /
• pp.238-243
• /
• 2006

• 한국신재생에너지학회:학술대회논문집
• /
• 2006.06a
• /
• pp.339-342
• /
• 2006

The power outputs of renewable energy such as wind turbines and solar energy powers depend on natural sources. Accordingly, the power outputs of renewable energy is different from capacity rate at the time of peak load. Because of this gap, long term electricity power plan can have over-estimated reserve margin. So, this paper suggests the chronological approach to calculate the reliability assessment of renewable energy.