• Transactions of the Korean Society of Automotive Engineers
• /
• v.10 no.2
• /
• pp.96-100
• /
• 2002

The purpose of this paper is presented a rational method of predicting dynamic/impact tensile strength of high tensile steel materials widely used fur structural material of automobiles. It is known that the ultimate strength is related with the loading speed and the Lethargy Coefficient from the tensile test. The Dynamic Lethargy Coefficient is proportional to the disorientation of the molecular structure and indicates the magnitude of defects resulting from the probability of breaking the bonds responsible for its strength. The coefficient is obtained from the simple tensile test such as failure time and stresses at fracture. These factors not only affect the static strength but also have a great influence on the dynamic/impact characteristics of the joist and the adjacent structures. This strength is used to analyze the failure life prediction of mechanical system by virtue of its material fracture. The impact tensile test is performed to evaluate the life parameters due to loading speed with the proposed method. Also the evaluation of the dynamic/impact effect on the material tensile strength characteristics is compared with the result of Campbell-Cooper equation to verify the proposed method.

• Geotechnical Engineering
• /
• v.12 no.1
• /
• pp.47-62
• /
• 1996

The bedding zone which influence directly to the safety of dam is supporting the face slab under hydraulic load in concrete faced rockfill dam. In case that leakage is developed due to various ruptured joint or cracks of face slab and etc., the bedding zone should limit the leakage by low permeability and keep the internal stability. In this study for the proper coefficient of permeability various properties, such as gradation, dry density, performance of embankment work and etc. were analysed. The results from the large scale test of permeability and density are summerized as follows : 1. Coefficient of permeability is decreased clearly by increase of dry density. 2. The particles smaller than the No.4 strive( p,) greatly influences the permeability under dry density of 2.24t 1 m3. 3. In case of C.40 and p,40%, even if dry density decreased to 2.0t/m3, the permeability coefficient is assumed to u x1-scm/s and internal stability is abtained. 4. Generally in dam construction since dry density and uniformity coefficient of bedding zone were higher than 2.2t/m3 and 50 respectively p, of 30~40% is assumed to be suitable and permeability coefficient of below 1$\times$10-3cm l s is expectable.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.9 no.1
• /
• pp.147-157
• /
• 2005

In this study, consolidation analysis methods reflecting various ground condition and changing coefficient of consolidation with consolidation process are presented. Research activities include development of numerical program consists of two parts considering vertical drainage only and both drainage condition with vertical and radial direction. Also, interface equation of adjacent two layers and function for changing coefficient of consolidation are added to developed program. This paper presents the results from a detailed consolidation analyses, which explores consolidation process with time in varying layered system and changing coefficient of consolidation

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.17 no.5
• /
• pp.23-29
• /
• 2018

This study is about the distribution of heat transfer in air conditioning ducts used for marine vessels and oil drilling platforms. As the convective heat transfer coefficient increased, heat transfer was conducted dynamically to inside as it exited to the outlet of duct. The experiment was to determine if the amount of heat transfer generated at the duct exit increased as the convective heat transfer coefficient increased. When the convective heat transfer coefficient was low, the temperature of the duct showed a relatively high temperature difference between the outside and inside of the duct due to the temperature influence of the internal fluid. In case of temperature distribution generated the volume of the duct along the change of the convective heat transfer coefficient, the temperature descended as heat transfer was promoted and the convective heat transfer coefficient increased.

• Geomechanics and Engineering
• /
• v.18 no.6
• /
• pp.567-574
• /
• 2019

In order to study the effect of stress and water pressure on the permeability of fractured rock mass under three-dimensional stress conditions, a single fracture triaxial stress-seepage coupling model was established; By using the stress-seepage coupling true triaxial test system, large-scale rock specimens were taken as the research object to carry out the coupling test of stress and seepage, the fitting formula of permeability coefficient was obtained. The influence of three-dimensional stress and water pressure on the permeability coefficient of fractured rock mass was discussed. The results show that the three-dimensional stress and water pressure have a significant effect on the fracture permeability coefficient, showing a negative exponential relationship. Under certain water pressure conditions, the permeability coefficient decreases with the increase of the three-dimensional stress, and the normal principal stress plays a dominant role in the permeability. Under certain stress conditions, the permeability coefficient increases when the water pressure increases. Further analysis shows that when the gob floor rock mass is changed from high stress to unloading state, the seepage characteristics of the cracked channels will be evidently strengthened.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.18 no.2
• /
• pp.7-13
• /
• 2019

This study is about distributions of heat transfer in air conditioning duct used for marine and oil drilling ship. As the convective heat transfer coefficient increased, heat transfer was conducted dynamically to inside as it exited to the outlet of duct. So, it was checked that the amount of heat transfer generated at duct increased as the convective heat transfer coefficient increased. In case the convective heat transfer coefficient was low, the temperature of duct showed the relatively high temperature distribution due to the temperature influence of internal fluid as the heat transfer between the outside and inside of the duct. In case of temperature distribution generated the volume of the duct along the change of the convective heat transfer coefficient, it was found out that the temperature descended as heat transfer was promoted and the convective heat transfer coefficient increased.

• Coupled systems mechanics
• /
• v.11 no.2
• /
• pp.93-106
• /
• 2022

The total embankment settlement consists of three stages: the initial settlement, the primary consolidation settlement, and the secondary consolidation settlement. The total embankment settlement is largely controlled by the primary consolidation settlement, which is usually computed with numerical models that implement Biot's theory of consolidation. The key parameter that affects the primary consolidation time is the coefficient of permeability. Due to the complex stress and strain states in the foundation soil under the embankment, to be able to predict the consolidation time more precisely, aside from porosity-dependency, the strain-dependency of the coefficient of permeability should be also taken into account in numerical analyses. In this paper, we propose a two-dimensional plane strain numerical model of embankment primary consolidation, which implements Biot's theory of consolidation with both porosity-dependent and strain-dependent coefficient of permeability. We perform several numerical simulations. First, we demonstrate the influence of the strain-dependent coefficient of permeability on the computed results. Next, we validate our numerical model by comparing computed results against in-situ measurements for two road embankments: one near the city of Saga, and the other near the city of Boston. Finally, we give our concluding remarks.

• Advances in concrete construction
• /
• v.13 no.6
• /
• pp.423-431
• /
• 2022

Although the influence of moisture content on the mechanical properties of concrete has been studied for a long time, research related to its influence on the damping and energy dissipation property of concrete structure is still very limited. In this paper, the relationship between damping property and moisture content of concrete using cyclic uniaxial compression is firstly presented, and the mechanism of the influence of moisture content on concrete damping and energy dissipation capacity is analyzed. Based on the experimental research, moisture-related damping and energy dissipation model is proposed. Results show that the dissipated energy of concrete and loss factor increase as the moisture content increasing. The energy dissipation coefficient reflecting the influence of stress level of concrete under cyclic load, decreases first and then increases as the moisture content increasing. The mechanism of moisture-related energy dissipation behavior can be divided into the reactive force of water, the development of the internal micro cracks and the pore water pressure. Finally, the proposed moisture-related damping and energy dissipation model are verified.

• The Journal of the Society of Korean Medicine Diagnostics
• /
• v.13 no.1
• /
• pp.10-18
• /
• 2009

Objectives : To review to determine difference in the effect of age, gender, location of electrode, test meal and period of recording that influence Electrogastrography (EGG) parameters and to study its oriental medical application. Methods : We investigate the research results through internet search engines, Pub Med, Karger, Mary Ann Libert and Pro Quest. Results : Age and gender influence postprandial Dominant Frequency Instability Coefficient (DFIC). Body mass index (BMI) influence fasting and postprandial EGG parameters. Menstrual cycle phase influence fasting Dominant Frequency (DF). Test meal volume and composition influence postprandial EGG parameters. But reduced-calorie test meal have no effect on EGG parameters. Conclusions : Because the amplitude of surface-recorded SW(slow wave) is very weak, EGG is influenced by many factors. Age, gender, BMI, menstrual cycle phase, test meal volume and test meal composition influence EGG parameters. but reduced-calorie test meal have no effect on EGG parameters.

• Journal of the Korean Home Economics Association
• /
• v.8 no.1
• /
• pp.181-197
• /
• 1970

Farm households consumption pattern from 1960 to 1968 was analized as follows. First, the influence of the price on the consumption pattern was observed by year for 9 years. Second, the influence of farm households and by size of the consmption pattern was analized by year for whole household and by size of the arable land. Third, the present status and problems of farm families consumption pattern was attempted to be found out compared with the pattern of all families of Seoul. Forth, the pattern of food expenditure which has the largest proportion in the living expenditure was analized. Following results and conclusions are obtained from the above analysis.1. The average nominal increase rate of all farm households has been increased gradually for 9 years, mostly due to the rise in household goods prices paid by farmers. 2. The living expenditure varies with the price and the disposal income, The influence of the latter is greater than that of the former. 3. The Engel's Coefficient of farmers. the average of which was 54.9%, recently tends to decrease gradually. The larger is the size of arable land, the lower is the Coefficient of farm households. But the Coefficient of farm households is higher than that of city families. 4. In general the proportion of food expenditure has a great influence on the consumption pattern, The average percentage of miscellaneous expenditure is 23.9% and it is next to food expenditure. The relationship between them is going reversely. Housing expenditure has usually the constant proportion. But the difference of the proportion between farm households (4.0%) and city families (17.1%) is considerable. Clothing expenditure and fuel and light expenditure have small variations. The former tends to increase with the income, and the latter tends to decrease with it or is constant. 5. Considering the food expenditure pattern, the average percentage (78.4%)of staple food of farm household is remarkably high compared with Seoul (48.3%) and other cities (54.0%). The decrease of the percentage of staple food expenditure in farm households is not so much as cities. 6. The propertion of the staple food expenditure of Farm families don't have so much differences by the size of arable land. But the rice proportion of staple foods has the tendency to increase with the income level. Subsidery food expenditure doesn't increase by year and by size of the land, while the consumption of meat and manufactured foods tends to increase with size of the land. But even big farm households don't reach to the level of cities in consumption of them. 7. Food consumption pattern may be influenced by the factors such as the knowledge of wife about nutrition, customs, consumption habits, and so on. The difference between farm households and city families in food consumption pattern is inferred from the above factors. Presently, the increasing income of the people promote the consumption of all items of living expenditure both in cities and farm households. But the Engel's Coeffcient and the proportion of the staple food expenditure is expected to decrease in farm households more than in cities.