• Journal of Power System Engineering
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• v.13 no.6
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• pp.29-34
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• 2009

Recently, we have a lot interest in a sudden rise of oil prices and a change weather for the earth warmming, so, development of new alternative fuels need in order to spare fossil fuel and reduce exhaust emissions for air pollution prevention. Biodiesel, which can be generated from natural renewable sources such as new or used vegetable oils or animal fats, may be used as fuel in diesel engine of compression ignition engine. In this paper, the combustion characteristics between neat diesel oil and biodiesel blends(10 vol.% biodiesel and 20 vol.% biodiesel) were tested using four stroke, direct injection diesel engine, especially this biodiesel was produced from soybean oil at our laboratory. This analysis showed that cylinder pressures, the rate of pressure rises and the rate of heat releases were decreased as the blending ratios of biodiesel to diesel oil increased because of lower heating value of biodiesel in spite of increased oxygen content in biodiesel.

• Journal of the Korean Society of Clothing and Textiles
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• v.24 no.6
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• pp.810-818
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• 2000

The purpose of this study was to analyze the effect of geometrical structure on the moisture transport properties of nonwoven batting materials. Two types of nonwovens were used such as single and double layered nonwovens. Steady and dynamic state water vapor transport properties were measured by absorption, evaporation and cobaltous chloride method respectively. The results of this study were as follows: 1) Geometrical structure affected water vapor evaporation, but there were no differences between single and double layered nonwovens in moisture absorption. Thickness and air permeability were influencing factor on water vapor transport rate. 2) Directionality of double layered nonwoven was observed both in steady and dynamic state moisture transport. There were differences between upper and lower layer of double layered nonwoven both in moisture absorption rate and color change by cobaltous chloride method. 3) In dynamic state of water vapor transport rate, single layered nonwoven reached more rapidly at the established relative humidity. It was confirmed that geometrical structure affected water vapor evaporation and hydrophilicity of fiber affected moisture absorption because there were much more water vapor transport rate by evaporation than absorption within the same period of time.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.50 no.5
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• pp.332-335
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• 2005

The three Korean wheat cultivars with different plant types; the erect, the middle and the creeping growth habit, were studied for their utilization to solar radiation, temperature changes on the furrow and to provide optimum planting space for producing the high yield in 2003. The average solar radiation rate was lowest for creeping type ($39.2\%$) and highest for erect type ($75.8\%$) The correlation coefficient between the coverage rate and the solar transmission rate was r = 0.8624 which was significant at $5\%$ level. The relative growth of the plant, tiller rate and leaf size was increased in the erect and the middle type at lower plant density, while no change on plant growth at creeping type regardless of plant density. The increase of leaf size in the lower plant density was due to longer flag and the first leaf than those of other plant types. The temperature on the furrow of growing plants was changed by the canopy. The changes in temperature pattern on the furrow according to plant types during winter season was different compared to the non plant ground. The temperature of the nonplant ground was the lowest due to solar reduction increasing the amount of cool air flowing in the furrow.

• Textile Coloration and Finishing
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• v.16 no.3
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• pp.31-38
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• 2004

Polyester fabrics, which is a major product in Daegu and Kyungbuk district, recently have a frequent warp streak phenomenon of sizing textiles for peach skin. So, this paper intensively focuses on the analysis of finding causes of poor products which may be produced in the process of sizing. Depending on the changes of sizing yarn's physical characteristic varying on sizing conditions, results of the research are as followed. 1. Sizing add-on rate, following tension changes of originally supplied yarn in sizing, does not fluctuate until 30g sizing tension, but marks high on the increase of sizing speed. 2. Sizing add-on amount increases approximately by 2.5% when interlacing pressure is raised from 1.5kg/$cm^2$ to 3.5kg/$cm^2$ at $130^{\circ}C$ sizing temperature. 3. Following the increase of sizing tension from 10g to 50g, boiling shrinkage rate of desizing yarn changes approximately from 7% to 11%. But the more sizing temperature and speed increases, the bigger the change rate becomes. 4. The thermal stress of desizing yarn is sensitively influenced by sizing tension in the sizing degree of above $130^{\circ}C$. 5. The deviation rate of sizing yarn's initial modulus value, which is influenced by air pressure in interlacing raw yarn, marks the highest at 40g and 50g strength.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2008.04a
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• pp.191-197
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• 2008

In this study, as a fuel filter for automobiles, base paper which can filtrate the polluted particles must satisfy with the standards of each vehicle. and a filter of impregnation paper made that combining the base paper with the resin. Therefore, They were wanted to found out the factors that affect base paper and impregnation paper according to content of HPZ, Mulberry pulp(MP), Laub holze bleached kraft pulp(LBKP). The most important things we wanted to find out in base paper and impregnation paper test were weight, thickness, air permeability, burst and tensile strength, maximum pore size and mean pore size, stiffness. we wanted to measure a rate of change of these condition by adjusting a rate of mixing for HPZ, MP and LBKP. Moreover, It suited for an impregnation paper mixed with a rate of mulberry pulp 20%, HPZ 40% and LBKP 40%. Used resins in this study was Phenol, Acryl, PVAc. And as every resins, sample was divided into existence and nothing of embossing. as a fuel filter for automobiles, It was appeared that the suitable condition of base paper was a rate of mixing for HPZ(40%), MP(20%) and LBKP(40%).

• Korean Journal of Agricultural and Forest Meteorology
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• v.19 no.1
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• pp.19-26
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• 2017

Surface air temperature ($T_{air}$) is a key variable for the meteorology and climatology, and is a fundamental factor of the terrestrial ecosystem functions. Satellite remote sensing from the Moderate Resolution Imaging Spectroradiometer (MODIS) provides an opportunity to monitor the $T_{air}$. However, the several problems such as frequent cloud cover and mountainous region can result in substantial retrieval error and signal loss in MODIS $T_{air}$. In this study, satellite-based $T_{air}$ was estimated under both clear and cloudy sky conditions in Gangwon Province using Aqua MODIS07 temperature profile product (MYD07_L2) and GCOM-W1 Advanced Microwave Scanning Radiometer 2 (AMSR2) brightness temperature ($T_b$) at 37 GHz frequency, and was compared with the measurements from the Automated Mountain Meteorology Stations (AMOS). The application of ambient temperature lapse rate was performed to improve the retrieval accuracy in mountainous region, which showed the improvement of estimation accuracy approximately 4% of RMSE. A simple pixel-wise regression method combining synergetic information from MYD07_L2 $T_{air}$ and AMSR2 $T_b$ was applied to estimate surface $T_{air}$ for all sky conditions. The $T_{air}$ retrievals showed favorable agreement in comparison with AMOS data (r=0.80, RMSE=7.9K), though the underestimation was appeared in winter season. Substantial $T_{air}$ retrievals were estimated 61.4% (n=2,657) for cloudy sky conditions. The results presented in this study indicate that the satellite remote sensing can produce the surface $T_{air}$ at the complex mountainous region for all sky conditions.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.8
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• pp.1153-1163
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• 2002

A transient analysis on temperatures of fuel and oil in hydraulic and lubrication systems in an aircraft was studied using the finite difference method. Numerical calculation was performed by an explicit method with modified Dufort-Frankel scheme. Among various missions, air superiority mission was considered as a mission model with 20% hot day ambient condition in subsonic region. The ambience of the aircraft was assumed as turbulent flow. Convective heat transfer coefficient were used in calculating heat transfer between the aircraft surface and the ambience. For an aircraft on the ground, an empirical equation represented as a function of free-stream air velocity was used. And the heat transfer coefficient for flat plate turbulent flow suggested by Eckert was employed for in-flight phases. The governing equations used in this analysis are the mass and energy conservation equations on fuel and oils. Here, analysis of fuel and oil temperature in the engine was not carried out. As a result of this analysis, the ground operation phase has shown the highest temperature and the largest rate of temperature increase among overall mission phases. Also, it is shown that fuel flow rate through fuel/oil heat exchanger plays an important role in temperature change of fuel and oil. This analysis could be an important part of studies to ensure thermal stability of the aircraft and can be applicable to thermal design of the aircraft fuel system.

• The Korean Journal of Community Living Science
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• v.28 no.1
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• pp.143-154
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• 2017

This study was conducted to develop fabrics using non-toxic and eco-friendly natural dyes made from curcuma and coffee extract. The natural dyes were applied to non-printed cotton fabrics using the dip dyeing method, and the pattern was hand-printed onto the dyed fabrics to make dyed printed-fabrics. The four types of developed fabric samples were compared to analyze the effects of the dyeing materials and printing on the hygienic properties of curcuma- and coffee-dyed fabrics. The findings were as follows. First, air permeability of both curcuma- and coffee-dyed fabrics was greatly affected by the presence of patterns, although the type of dye did not seem to have an effect. Printing greatly reduced air permeability of the fabric, and coffee-dyed fabric showed greater reduction of dyeing method than curcuma-dyed fabric. Moisture regain also tended to decrease with printing, but the change was much smaller compared to air permeability. Second, increased UV blockage was observed in curcuma- and coffee-dyed fabrics with patterns compared to non-printed fabrics, showing that printing enhanced UV blocking. Third, deodorization rate tended to increase sharply for both curcuma- and coffee-dyed fabrics until 30 minutes and gradually increased thereafter to yield 30% for curcuma and 50% for coffee at 120 minutes, demonstrating higher deodorization of coffee dye. Coffee-dyed fabric showed an antibacterial rate about twice as high as that of curcuma-dyed fabric, and the observed data suggest that curcuma-dyed fabric had an insignificant level of antibiosis. Fourth, printing significantly enhanced wash, sunlight, and compound colorfastness of the two types of dyed fabrics. The effect of printing was most dramatic on sunlight and compound colorfastness, which are aspects in which natural dyed fabrics perform poorly in general. Eventually, the development and application of biologically- and environmentally-friendly fabrics with natural dyes correspond with increased interest towards the wellness and healthy attitudes of modern society.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.20 no.1
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• pp.26-33
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• 2012

Competition between air transportation and railways has grown fiercer in major countries around the world with the rise of high-speed railways. In South Korea, air passenger travel has been rapidly decreasing since the initial launch of the Seoul-Pusan KTX line in 2004 and second opening that followed in 2010. Further expansion of the high-speed railway is expected. At present, research efforts to verify the validity of constructing an underwater express railway tunnel between Ho-nam and Jeju Island are taking place. Considering the possible high speed railway connection between Seoul and Jeju Island, this thesis has analyzed the choice behavior of existing passengers of the major and low-cost carriers. For this, Stated Preference (SP) research has been performed for three variables, including fare, travel time and the number of runs, to estimate the substitution rate of each of the three variables. Binomial Logit Model has been estimated with the obtained data. The estimation of the model has found that airline passengers of major and low-cost carriers are willing to pay approximately 7,200 KRW and 5,000 KRW, respectively, to reduce travel time by one hour. If the number of runs in one day increases, it has been estimated that the passengers are willing to pay additional fares of about 390 KRW and 30 KRW, respectively. On the other hand, the substitution rate between the number of runs and the travel time was found to be somewhat insignificant. If the construction of the Seoul-Jeju line progresses in the future, this study could be used as preliminary data for determining fares, travel time and the number of runs.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.6 no.3_4
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• pp.101-111
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• 1973

To study the effect of freezing rate on the duality of frozen abalone(Haliotis gigantea, GMELIN) liquid nitrogen spray freezing, air blast freezing, semi-air blast freezing, and still air freezing were carried out. The rheological change, protein denaturation, and free water content of frozen and thawed abalone were examined at the period of 0, 1, 2, and 3 month during cold Storage at $-20^{\circ}C$. The results are summarized as follows : 1. The onset and duration of rigor mortis of fresh abalone was faster and shorter as compared to that of fishes. 2. There was no difference in compression value and shear value between freezing methods but they varied with a slight decrease in storage period. 3. Gradual decrease in extractibility of salt soluble protein was observed in all samples except those frozen with liquid nitrogen. 4. The free water of the foot muscle remained constant during the storage while that of the adductor muscle tended to increase. 5. A significant correlation was observed among the changes of panel texture and free water (P< 0.01), protein denaturation (P<0.05), and compression value (P<0.01).