• Journal of Ocean Engineering and Technology
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• v.16 no.2
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• pp.53-59
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• 2002

This paper shows the experimental results controlling the height of surface and back bead in GMAW by analyzing the unexpected gaps between base metals produced in welding and by controlling welding velocity due to the variation of the gap between base metals in thin-plate welding. The back bead behavior and burn-through in I-type butt joint $CO_2$ welding of thin mild steel are analyzed in the views of short circuit time ratio and short circuit frequency. It is shown through experimental consideration that the short circuit time ratio method is more reasonable than the short circuit frequency method in analyzing the formulation of back bead under changing the gap between base metals. Based on the these results, welding manipulator is designed so as to satisfy the bead height control in real time by measuring the short circuit time ratio. To show the effectiveness of the developed bead formulation control system, the experiment is implemented under two welding conditions such as increasing gap from 0mm to 0.8mm and gradually increasing gap from 0mm to 1.2mm. The experimental results show that the bead formulation can be controlled uniformly in spite of the variation of the gap between base metals.

• Journal of the Korean Society of Propulsion Engineers
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• v.11 no.5
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• pp.14-22
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• 2007

A reversed trapezoidal fin with variable lateral surface slope is optimized using a two-dimensional analytic method. For a fin base boundary condition, convection from the inside fluid to the inside wall and conduction from the inside wall to the fin base are considered. Heat loss from the fin tip surface is not ignored. The maximum heat loss at the practical fin length, the corresponding optimum fin efficiency, fin length and fin base height are presented as a function of the fin inside and outside convection characteristic numbers. One of the results shows that the optimum fin shape becomes 'fatter and shorter' as the ratio of fin tip height to base height increases.

• The Korean Journal of Ecology
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• v.25 no.1
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• pp.29-31
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• 2002

The purpose of this study is to estimate height growth patterns and site index cuties (base index age 50 years) for Japanese red cedar trees(Cryptomeria japonica D. Don) grown in southern regions of Korea. The Chapman-Richards growth function was selected for stand height prediction using on the results of stem analysis data sets. Anamorphic base age invariant site index cuties were presented based on this height prediction equation. The resulting site index prediction equation can provide an indication of the productivity of the site quality based on Japanese red cedar trees plantation ages planted in southern regions of Korea.

• International Journal of Ocean System Engineering
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• v.2 no.2
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• pp.92-96
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• 2012

This study presents a rockfall impact analysis of a typical roadway. Dynamic finite element analyses using ANSYS AUTODYN are conducted to determine the effect of the drop heights (5 m, 10 m) on the damage to a roadway model. The Rockfall is modeled as a spherical shape with a weight of 400 kg, and each drop height is converted to a corresponding impact velocity to save computational time. The roadway model is comprised of an asphalt layer, base layer, sub-base layer, and sub-grade layer. In this paper, the asphalt is modeled using a linear elastic model. The base layer, sub-base layer, and sub-grade layer are modeled using a Mohr-Coulomb model. From the analyses, the effects of the drop height on the damages and stresses are examined and discussed.

• Geomechanics and Engineering
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• v.1 no.3
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• pp.219-239
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• 2009

Vertical vibration tests were conducted using model footings of different size and mass resting on the surface of finite sand layer with different height to width ratios and underlain by either rigid concrete base or natural red-earth base. A comparative study of the ratio of predicted and observed natural frequency ratio of the finite sand stratum was made using the calculated values of equivalent stiffness suggested by Gazetas (1983) and Baidya and Muralikrishna (2001). Comparison of results between model footings resting on finite sand stratum underlain by the rigid concrete base and the natural red-earth base showed that, the presence of a finite base of higher rigidity increases the resonant frequency significantly. With increase in H/B ratio beyond 2.0, the influence of both the rigid concrete and natural red-earth base decreases. Increase in the contact area of the footing increases the resonant frequency of the model footings resting on finite sand stratum underlain by both the types of finite bases. Both the predicted and the observed resonant frequency ratio decreases with increase in force rating and height to width ratio for a given series of model footing.

• Earthquakes and Structures
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• v.16 no.1
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• pp.1-9
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• 2019

To provide a simplified method for the base isolation design of LNG tanks, such as $16{\times}104m^3$ LNG tanks, we conducted a derivation and calculation example analysis of the dynamic response of the base isolation of LNG storage tanks, using dynamic response analysis theory with consideration of pile-soil interaction. The ADINA finite element software package was used to conduct the numerical simulation analysis, and compare it with the theoretical solution. The ground-shaking table experiment of LNG tank base isolation was carried out simultaneously. The results show that the pile-soil interaction is not obvious under the condition of base isolation. Comparing base isolation to no isolation, the seismic response clearly decreases, but there is less of an effect on the shaking wave height after adopting pile top isolation support. This indicates that the basic isolation measures cannot control the wave height. A comparison of the shaking table experiment with the finite element solution and the theoretical solution shows that the finite element solution and theoretical solution are feasible. The three experiments are mutually verified.

• Journal of The Korean Association For Science Education
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• v.4 no.1
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• pp.15-25
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• 1984

The purpose of this study is to develop a practical and ideal model of science laboratory enrolled 48-60 students by studying optimal facilities such as laboratory tables and chairs proper to elementary school settings. The science laboratory model was figured out in terms of the following six procedures; (1) Current status as well as problems of science laboratory and its facilities was identified by means of the questionnaires conducted to 201 elementary schools, using stratified cluster sampling tehnique, under the consideration of the school size and the regional characteristics across the country. (2) Collected were the anthropometric data with respect to sitting height, popliteal height, buttock popliteal length, elbow rest height, and back width from the 747 students, 4th-6th grade, in Seoul area. (3) It was measured the work apace necessary for individual student to perform his experiment. (4) Using the data of the process (2), we determined the optimal sizes of laboratory tables and chairs fitted for Korean elementary school students. (5) The optimal area of science laboratory for 48-60 students is determined in terms of the data obtained in (3) for individual work space in addition to the appropriate table size figured out by (4). (6) A practical and ideal model for a science laboratory in elementary school was designed according to the above procedures. For the optimal model of science laboratory, the results of this study can be summarized as follows: The sizes of chair and table are categorized into three groups such as small, medium, and large depending on students' physical outfit. The small size base on the 12.5th percentile point of students' sitting height is used for students of the 0-25th percentile ranks. The medium size base on the 50th percentile point of students' sitting height is used for students of the 26-75th percentile ranks. The large size base on the 87.5th percentile point of students' sitting height is used for students of the 76-100th percentile ranks. (1) Sizes of chairs: The small size is 28cm in width and 33cm in height. The medium size is 31cm in width and 36cm in height. The large size is 35cm in width and 38cm in height. (2) Sizes of laboratory tables: The small size is 120cm in length, 86cm in width, and 60cm in height. The large size is 120cm in length, 86cm in width, and 60cm in height. The large size is 120cm in length, 86cm in width, and 65cm in height. (3) Size of science laboratory: The optimal science laboratory for 48-60 elementary school students, which can install the 12 laboratory tables, is 12m in length and 10m in width.

• The korean journal of orthodontics
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• v.39 no.1
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• pp.28-35
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• 2009

Objective: The purpose of this study was to investigate the relationship between menarche and cervical vertebral maturation. Methods: Lateral cephalograms of 67 young korean girls within the range of 1 year before or after their menarche were gathered. The concavity of the cervical vertebrae base and the ratio of the base length to the 3rd and 4th cervical vertebrae anterior height were measured and analyzed. Results: The mean measured values were as follows, concavity of the 3rd cervical vertebrae base: 1.27(${\pm}0.18$) mm, concavity of the 4th cervical vertebrae base: 1.06(${\pm}0.15$) mm, ratio of the base length to the 3rd cervical vertebrae anterior height: 0.73(${\pm}0.06$) and ratio of the base length to the 4th cervical vertebrae anterior height: 0.70(${\pm}0.05$). There was a significant increase in the ratio of the base length to the 3rd vertebrae anterior height and the base concavity of the 3rd and 4th cervical vertebrae during the period of 1 year before to 1 year after their menarche. Conclusions: These characteristics of the 3rd and 4th cervical vertebrae on the lateral cephalogram can provide useful clues on evaluating the growth stage.

• Magazine of the Korean Society of Agricultural Engineers
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• v.6 no.2
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• pp.816-825
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• 1964

1. Outline: The flow of the siphon spillway is very intricate and affected by vacuous condition. It is an intresting problem to make vacuum rapidly in_siphon, i.e, to provoke the perfect siphonaoge with the lowest water-level of overflow. The hydraulic experiments of siphon spillway have practiced at the Masan Lake, Haenam, the province of Junnam and gained rational and economical results which cannot be odtained by calculation. 2. Experiment: The model scale was a half of that of the prototype. 3. Results and discussion: In the experiments of 14 runs, washing, overflow water level, outlet, water level of cushion, phenomenon of water flying and water pressure of every part, etc. were studied. a) The relation of overflow water-level at siphon inlet and deflector When the elevation of the deflector is 10. 65m and the form of deflector O.4m long is the hypotenuse of an $45^{\circ}$ isosceles triangle, the over flow water-level is the minimum, i. e. the siphonage was excellent. There is no effect by the rising of overflow water-Ievel between 11.95m to 1O.65m of deflector elevation (in the first plan, it is 11.05m). But the overflow water-level rises remarkably in the outside region of the above limits. b) The relation of overflow water-level, the length of cushion and standard height of the base. The reduction of the length of cushion brings the rising of overflow waterlevel, and the rising of the standard height of the base brings the rising of overflow water level. For the long cushion length and low standard height of the base, it cannot be expeted to have the falling of overflow water-level. The most satisfactory data were obtained at 5.20m of the base standard height and 6.1m of the length of cushion. The first vah,le planned was 5.70 m and 4.30m.

• Education of Primary School Mathematics
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• v.19 no.2
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• pp.113-125
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• 2016

The concept and measuring activities of the height of figures are essential to find the areas or volumes of the corresponding figures. For plane figures, the height of a triangle is defined to be the line segment from a vertex that is perpendicular to the opposite side of the triangle, whereas the height of a parallelogram(trapezoid) is defined to be the distance between two parallel sides. For the solid figures, the height of a prism is defined to be the distance of two parallel bases, whereas the height of a pyramid is defined to be the perpendicular distance from the apex to the base. In addition, the height of a cone is defined to be the length of the line segment from the apex that is perpendicular to the base and the height of a cylinder is defined to be the length of the line segment that is perpendicular to two parallel bases. In this study, we discuss some pedagogical problems on the concepts and measuring activities of the height of figures to provide alternative activities and suggest their educational implications from a teaching and learning point of view.