• Journal of Biosystems Engineering
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• v.9 no.1
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• pp.11-21
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• 1984

This study was intended to analyze the dynamic force system which induced the shattering of paddy grains. A model to predict the shattering of paddy grains was developed, and physical quantities, such as mass distribution and rigidity of rice plant, needed for evaluating the minimum shattering forces were also measured. Under the assumption that rice plant right before harvesting is a vibratory system, the mathematical model of the vibratory system was developed and solved with the varied conditions of forcing functions. The results of the study were summarized as follows: 1. The shattering of grain occurred at the abscission layer of grain by the bending moments resulted from the impact force due to the collision of panicles of rice plant. 2. The vibratory model developed for milyang 23 rice variety was analyzed to give the natural frequencies of 7-9 Hz, which were closely related with the excitation frequencies of 4-10 Hz caused by various machine parts besides engine. Thus, avoiding the resonance should be taken into consideration in the design of the harvesting machinery. 3. It was analyzed to predict the lowest frequency that could develop the shattering when the excitation force was applied to the lower end of stem. The lowest frequency for the Milyang 23 rice variety ranged from 8.33 Hz to 11.66 Hz as the amplitude varied from 1 cm to 2.5 cm. 4. The degree of shattering depended upon the magnitude of the impact force and its application point. For Milyang 23 rice variety, the minimum impact force developing the shattering was $5g_f$ when it was applied at 1 cm above the lower end of stern and $1g_f$ when applied at 5 cm above the lower end of stem. 5. The minimum colliding velocity of the panicle, when it was on the ground that would just develop the shattering, was given as follows, $$V=\sqrt{\frac{K_t}{m_g}{\cdot}{{\phi}^2}}$$ where V : The colliding velocity of the panicle against ground to cause the shatteering of rice grain. (cm/sec) $K_t$ : The minimum spring constant for bending at the abscission layer of grain. (dyne-cm/rad) ${\phi}$ : The minimum shattering angle of grain (rad) $m_g$ : The maximum mass of grain. (g).

• Journal of Korean Society of Transportation
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• v.22 no.7 s.78
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• pp.147-154
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• 2004

The purpose of this paper is to improve the existing phase split algorithm considering the minimum green time in COSMOS. In the case of a signalized intersection where two wide and narrow streets intersect each other, the time required for the pedestrian crossing is frequently longer than the time alloted to the through traffic on a minor street. In order to meet the minimum green time requirement for the pedestrian less time in alloted automatically to the left-turn traffic, creating heavy congestion on the left-turn approach. To solve this problem, this study suggests a new algorithm which shares the barrier using minimum green time and shares the burden with signal phases alloted to the crossing street traffic on the basis of the equal ratio of the degree of saturation, while maintaining the minimum green time requirement. The new algorithm was compared with the existing algorithm by using a microscopic simulation model for COSMOS evaluation developed at Ajou University. The simulation results show that the new algorithm produces better performance than the existing one.

• Proceeding of Spring/Autumn Annual Conference of KHA
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• 2008.04a
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• pp.203-208
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• 2008

The purpose of the study is to establish the concept of residential standard, and at the same time to investigate the area of the minimum residential standard in the countries of the world through the preceding studies. In addition, it also aims at establishing the objective residential standard by comparing the residential standard of Korea with that of foreign countries, examining the problems and finding out the matters to be improved through the comparison of the residential standard in advanced countries with the minimum residential standard of Korea. The standard residential area, derived from the process of examining the minimum residential standard, will be used as the basic material for the calculation of the reasonable area in the surface plan for the study of low-cost housing development. The method of the study is to establish the concept of residential standard and at the same time to find out the problems in the minimum residential standard of Korea and improvement methods through the comparison of the residential standards in other countries. As the result of the studies focused on the area among the residential standards, it is found out that the Korea's residential area per capita is established as the least in comparison with that of advanced countries. The real area decided depending on the size of social space suitable for living can play a role in improving the degree of satisfaction in the person's living in the residential area. Therefore, it is urgently necessary to make a depth study on the surface area of the minimum residential standard, and it is also required to propose the residential standard and directions for the improvement of the qualitative level rather the quantitative expansion of residential structures.

• Proceedings of the KIEE Conference
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• 1995.07c
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• pp.1394-1397
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• 1995

In the hazardous areas where explosive gases, vapor or mists exist, electrical apparatus and installations must be of explosion-proof construction to prevent or limit the danger of the ignition of potentially explosive atmosphere. In Korea, nine types of protection have been specified in the government regulations at present: flameproof enclosure, pressurization, oil immersion, increased safety, intrinsic safety, non-incendive, sand filling, encapsulation, and special types. Among these types, the intrinsic safety has the construction which limit or by-pass igniting the electric energy using electronic devices. This type has lots of merits but at the same time requires a high-degree of technology. In this paper, we investigated several dominating factors which affect the minimum ignition energy: this energy plays a very important role in design and evaluation of the intrinsic safety type electrical apparatus. Eletrode material, which is one of the most important factors, was intensively studied for the five sorts of material(Al, Cd, Mg, Sn, and Zn) with performing experiment in a low-voltage inductive circuit using IEC-type spark apparatus. The experimental results show that the minimum ignition energy of electrode material is varied: highest in Cd and lowest in Sn. We also confirmed the effect of eletrode make-and-break speed and magnetic field magnitude.

• Geomechanics and Engineering
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• v.7 no.5
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• pp.525-537
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• 2014

The typical design of ground improvement with prefabricated vertical drains (PVD) and surcharge preloading involves a series of deterministic analyses using averaged or mean soil properties for the various combination of the PVD spacing and surcharge preloading height that would meet the criteria for minimum consolidation time and required degree of consolidation. The optimum design combination is then selected in which the total cost of ground improvement is a minimum. Considering the variability and uncertainties of the soil consolidation parameters, as well as considering the effects of soil disturbance (smear zone) and drain resistance in the analysis, this study presents a stochastic cost optimization of ground improvement with PVD and surcharge preloading. Direct Monte Carlo (MC) simulation and importance sampling (IS) technique is used in the stochastic analysis by limiting the sampled random soil parameters within the range from a minimum to maximum value while considering their statistical distribution. The method has been verified in a case study of PVD improved ground with preloading, in which average results of the stochastic analysis showed a good agreement with field monitoring data.

• Bulletin of the Korean Space Science Society
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• 2008.10a
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• pp.23.4-23.4
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• 2008

In March and April 2001, the apogee (~9 Re) of the Polar spacecraft was located near the subsolar magnetopause with its orbital plane nearly parallel to a magnetic meridian plane. Polar electric and magnetic field data acquired during the two-month interval of solar maximum have been used to study fundamental standing Alfven waves near the subsolar meridian plane (magnetic local time = 1000-1400 hours) at magnetic latitudes from the equator to $\pm45$ degrees and at L values between 7 and 12. In the frequency band from 1.5 to 10 mHz, fundamental mode oscillations were identified based on high coherence (more than 0.7) and an approximately 90-degree phase shift between the azimuthal magnetic and radial electric field components. The L dependence of the fundamental frequencies is studied, and the frequencies are compared with those observed near the solar minimum interval (Takahashi et al. 2001). We found that the average frequencies in solar maximum are lower than those in solar minimum by a factor of ~2. This implies that the mass density in solar maximum is higher than that in solar minimum by a factor of ~4. Since there is a positive correlation between solar irradiance and solar activity, we suggest that the ionosphere in solar maximum produces more ions and load magnetic flux tubes with more ions.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.10a
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• pp.321-325
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• 2004

Linear motor feed drive systems have been broadly used in machine tools or precision automatic feed systems. Recently, modem machine tools require high speed and high precision feed drive system to achieve high productivity. Unfortunately, a feed drive system, even though it was optimum designed, may experience severe transient vibrations during high-speed operation if its feed rate control is unsuitable. A rough feed rate curve having discontinuity in its acceleration profile causes a serious vibration problem in the feed slides system. This paper presents a feed rate optimization of a machine tool feed slide system, which is driven by a linear motor, for its minimum vibrations. Firstly, a 4-degree-of-freedom lumped parameter model is proposed for the vibration analysis of a linear motor driven machine tool feed drive system. Next, a feed rate optimization of the feed slide is carried out for minimum vibrations. The feed rate curve optimization strategy is to find out the most appropriate acceleration profile with jerk continuity. Of course, the optimized feed rate should approximate to the desired one as possible. A genetic algorithm with variable penalty function was used in this feed rate optimization.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.962-966
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• 2004

Ball screw feed drive systems have been broadly used in machine tools or precision automatic feed systems. Recently, modern machine tools require high speed and high precision and drive system to achieve high productivity. Unfortunately, a feed drive system, even though it was optimum designed, may experience severe transient vibrations during high-speed operation if its feed rate control is unsuitable. A rough feed rate curve having discontinuity in its acceleration profile causes a serious vibration problem in the feed slide system. This paper presents a feed rate optimization of a machine tool feed slide system, which is driven by a ball screw, for its minimum vibrations. Firstly, a 6-degree-of-freedom lumped parameter model was proposed for the vibration analysis of a ball screw driven machine tool feed drive system. Next, a feed rate optimization of the feed slide was carried out for minimum vibrations. The feed rate curve optimization strategy is to find out the most appropriate acceleration profile having finite jerk. Of course, the optimized feed rate should approximate to the desired one as possible. A genetic algorithm with variable penalty function was used in this feed rate optimization.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.3
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• pp.1030-1050
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• 2021

The edges with "bridge characteristic" play the role of connecting the communication between regions in power optical cable network. To solve the problem of mining edges with "bridge characteristic" in provincial power optical cable network, the complex power optical cable network model is constructed. Firstly, to measure the generated potential energy of all nodes in n-level neighborhood local structure for one edge, the n-level neighborhood local structure topological potential is designed. And the minimum connected chain attenuation is designed to measure the attenuation degree caused by substituted edges. On the basis of that, the minimum connected chain attenuation topological potential based measurement is designed. By using the designed measurement, a bridge-edges mining algorithm is proposed to mine edges with "bridge characteristic". The experiments are conducted on the physical topology of the power optical cable network in Jilin Province. Compared with that of other three typical methods, the network efficiency and connectivity of the proposed method are decreased by 3.58% and 28.79% on average respectively. And the proposed method can not only mine optical cable connection with typical "bridge characteristic" but also can mine optical cables without obvious characteristics of city or voltage, but it have "bridge characteristic" in the topology structure.

• Korean Journal of Food Science and Technology
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• v.17 no.1
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• pp.5-7
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• 1985

Effect of phosphate (sodium polyphosphate 85%, sodium hexametaphosphate 7% and potassium phosphate 7%) on gelatinization of nonwaxy and waxy rice starches was investigated with X-ray diffractometry. The minimum moisture content for the gelatinization of nonwaxy starches was lowered in the presence of phosphate. The minimum temperature for the gelatinization of 5% starch suspensions was not altered by phosphate. However, the degree of gelatinigation of rice starches at the same temperature was higher in the presence of phosphate, except waxy rice starch.