• Journal of the korean Society of Automotive Engineers
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• v.7 no.1
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• pp.35-42
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• 1985

This paper describes an experimental study of the effect of injection timing on the combustion characteristics in four stroke cycle diesel engine with direct injection type combustion chamber. The effect of injection timing and compression ratio of engine on the combustion characteristics are investigated. Experimental results of combustion characteristics in cylinder show that the combustion pressure and the rate of pressure rise decrease in accordance with the retard of fuel injection timing. It is observed that the rate of pressure rise in cylinder is increased an increase in the compression ratio of engine. The effect of the fuel injection timing on the frequency of cylinder pressure brings about the same trend of the maximum rate of pressure rise in cylinder.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.11a
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• pp.649-656
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• 2000

Consolidation of the ground surrounding the sand piles is delayed by well resistance and smear effect. This study is executed to understand the factors that affect the characteristics of consolidation. This was accomplished by utilizing the estimated and measured values of the soil properties through the monitoring of the ground surrounding the sand piles. When it is assumed that the horizontal coefficient is equal to the vertical coefficient of consolidation, the estimated values is exceedingly similar to the measured values. The properties of the initially disturbed soil by the sand pile installation seemed to improve through the process of consolidation with the passage of time. From the results of the analysis of the settlement measurement, the measured values occurred about 60～90% of the predicted values. Considering the initial radical compression deformation, according to the theory of cavity expansion, the difference between the two appears to be in good agreement. In this study, to understand the behavioral characteristics of the ground surrounding the sand piles requires estimation through considering the initial radial compression as well as smear effect of the soil disturbance and well resistance.

• Magazine of the Korean Society of Agricultural Engineers
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• v.15 no.2
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• pp.2968-2979
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• 1973

The aim of this study was to bring light on the effect of permeability to yield weight of paddy rice on the compressed soil. a) The percolation volume during the growth of paddy rice reduced, while the degree of compression on soil column increased and varied by the evaporation and absorption volumn. b) The percolation volume in the natural soil column was notably low compared with that of in the artificial and had little influence to the variation of permeabilty by compression. c) The results in growth of paddy rice were best on the section of low compression and the yield weight reduced, while the degree of compression on the soil column increased. d) The relationship between the yield weight and percolation volumn, under the condition when percolation volume is 1mm/day, had little difference in the yield weight but immediately reduced under $0.5{\sim}1.0mm/day$. The consequences of investigation are not so perfect, but have done my best to get some new data for effect on additional yield by inquiring into influences of permeability to the yield weight of paddy rice on compressed paddy field. I will have a great pleasure if treatise helps investigaters or the men of affairs in this field.

• Journal of the Korean Wood Science and Technology
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• v.39 no.4
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• pp.303-310
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• 2011

The mechanical properties of heat-compressed Radiata pine (Pinus radiata D.Don) by compression temperature and time were investigated. The compressive strength and bending strength of heat-compressed wood increased with increasing compression temperature and time. But the compressive strength and bending strength decreased with press temperature $220^{\circ}C$. It was considered due to thermal degradation during high temperature conditions. The surface hardness of heat-compressed wood increased with increasing compression temperature. However, the effect of compression time was negligible. The nail holding power was not affected by compression temperature and time.

• Journal of Power System Engineering
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• v.18 no.1
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• pp.57-62
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• 2014

This paper present the performance characteristics of R404A two-stage compression refrigeration system. The operating parameters considered in this study include evaporating and condensing temperature, subcooling and superheating degree, compressor efficiency. The main results were summarized as follows: The COP of two-stage compression refrigeration system using R404A has an effect on the variation of evaporation temperature, condensation temperature, subcooling degree and compressor efficiency, but not an effect on the superheating degree. R404A two-stage compression refrigeration system is unstable because COP of this system is significantly changed when evaporating temperature and compressor efficiency decreased. In particular, when compressor efficiency decreased, COP is significantly decreased. This is inefficient for long-term use.

• Korean Journal of Food Science and Technology
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• v.17 no.6
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• pp.469-473
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• 1985

The typical force-distance curves by puncture test and Back Extrusion test of acorn flour gels were investigated. Kc' and Ks' were calculated to estimate the compression and shear components of a puncture force. In this study, compression effect played a major role. The more concentration of acorn flour gel and diameter of probe increased, the more compression force contributed to the puncture force. In the Back Extrusion test, the effect of increasing the sample size was to extend the length of the plateau without affecting the maximum force. However, as the concentration of acorn flour gel increased, maximum Extrusion force became larger.

• Fashion & Textile Research Journal
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• v.8 no.3
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• pp.363-369
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• 2006

In this the study, Lyocell fabrics for blanket were developed to get high value added goods for elder and Infant. Therefore, the purpose of the study was determine the effect of twist per inch on the physical properties of developed fabrics, including compression property and abrasion resistance on the process for making Lyocell combined yarns. For comparison, commonly used cotton blanket was used. The results were as the follows: 1) Dimensional changes of Lyocell fabrics was in -3% which value was pretty stable, and antistatic property was very good with 10V of electric propensity voltage which means there was no static electricity at all. Pilling property of Lyocell fabrics showed 3 grade which was good and air permeability and moisture vapor transmission rate of Lyocell fabrics were higher than those of cotton fabric and keeping warmth rate of Lyocell fabrics was about 50% which means it very warms. 2) Twist per inch of Lyocell combined yarns increased with tensile strength and elongation of Lyocell fabrics. 3) Twist per inch of Lyocell combined yarns increased with decreasing thickness reduction rate and therefore, compression property of those was pretty good. Specially, compression property of Lyocell fabrics made with yarns of 3.9TPI was better than those of cotton fabric. 4) Twist per inch of Lyocell combined yarns increased with abrasion resistance of Lyocell fabrics.

• Journal of the Korean Institute of Gas
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• v.3 no.1
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• pp.14-20
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• 1999

This study describes the results of Coefficient of Performance(COP) analysis by cycle simulation for two types of absorption-compression hybrid cycle using the Water/Lithium Bromide solution pair. These types are basic hybrid systems introducing a mechanical compression process into the refrigerant vapor phase of the single effect absorption cycle. In absorption-compression hybrid cycles, coefficient of performance is improved compared with absorption cycle. Hybrid cycle Type 2 is considered as a key technology to support energy utilization system, given its capability of utilizing waste heat to drive system with a high level of efficiency.

• Geomechanics and Engineering
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• v.21 no.4
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• pp.315-326
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• 2020

The long-term behavior of rockfill material used in the construction of infrastructures such as dams is of great significance. Because of concerns about the application of weak rockfill material in dam construction, further experimental studies on the behavior of these materials are required. In this study, laboratory experiments were performed to investigate the one-dimensional deformation and particle breakage of the weak rockfill material under stress. A one-dimensional compression apparatus was designed and developed for testing of rockfill materials of different maximum particle sizes (MPSs). The compression tests were performed under dry, wet and saturated conditions on samples of rockfill material obtained from a dam construction site in Iran. The results of the experiments conducted at the specimen preparation stage and the 1D compression tests are presented. In weak rockfill, the effect of the addition of water on the behavior of the material was uncertain as there were both an increases and decreases observed in particle breakage. Increasing the MPS of the weak rockfill materials increased particle breakage, which was similar to the behavior of strong rockfill material. In all of the MPSs examined, the settlement of specimens under wet conditions was higher than that observed under dry conditions. Also, the greatest deformation occurred during the first hour of loading.

• Journal of the Korean earth science society
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• v.32 no.6
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• pp.575-585
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• 2011

The effect of wavelet pair choice in the compression of the satellite images is studied. There is a trade-off between compression rate and perception quality. The encoding ratio is used to express the compression rate, and Peak Signal-to-Noise Ratio (PSNR) is also used for the perceptional performance. The PSNR and the encoding ratio are not matched well for the images with various wavelet pairs, but the tendency is remarkable. It is hard to find the pattern of PSNR for sampled images. On the other hand, there is a pattern of the variation range of the encoding ratio for each image. The satellite images have larger values of the encoding ratio than those of nature images (close range images). Depending on the wavelet pairs, the PSNR and the encoding ratio vary as much as 13.2 to 21.6% and 16.8 to 45.5%, respectively for each image. For Synthetic Aperture Radar (SAR) images the encoding ratio varies from 16 to 20% while for the nature images it varies more than 40% depending on the choice of wavelet pairs. The choice of wavelet for the compression affects the nature images more than the satellite images. With the indices such as the PSNR and the encoding ratio, the satellite images are less sensitive to the choice of wavelet pairs. A new index, energy concentration ratio (ECR) is proposed to investigate the effect of wavelet choice on the satellite image compression. It also shows that the satellite images are less sensitive than the nature images. Nevertheless, the effect of wavelet choice on the satellite image compression varies at least 10% for all three kinds of indices. However, the important of choice of wavelet pairs cannot be ignored.