• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.22 no.6
• /
• pp.349-356
• /
• 2021

Since the 1960s, traffic infrastructure, such as bridges, has increased rapidly in Korea as urbanization and industrialization progressed due to economic growth. As the scale of the bridge becomes larger, stability analysis of the superstructure of the bridge is being conducted actively, but scour stability analysis for the substructure of the bridge has not been conducted sufficiently. This study is a basic investigation to prevent large-scale disasters caused by scouring in bridge piers. A simple linear regression model was used to analyze the scour depth calculated through seventeen scour depth calculation formulae, and the scour depth measured through hydraulic model experiments. As a result, the Coleman (1971) formula was the best method among the scour depth calculation formulae, and the Froehlich (1987) formula was the most effective method for calculating the scour depth. In addition, a review using a simple regression model confirmed that the scour depth calculation formulae of CSU (1993), Coleman (1971), and Froehlich (1987) can predict a similar scour depth by reflecting domestic stream characteristics. This study can calculate the scour depth reflecting the environmental conditions of Korea in future stream design.

• Journal of Korean Society of Forest Science
• /
• v.111 no.4
• /
• pp.630-643
• /
• 2022

This study was conducted to derive the fresh weight and dry weight estimation formulas of Pinus densiflora and prepare a weight table using them. Aone-variable formula using only the diameter at breast height (DBH) and a two-variable formula using DBH and height were used to calculate the fresh and dry weight. Each equation was verified using statistics, such as fit index, standard error, and residuals. Theoptimal equation was evaluated for applicability by calculating the weight as a coefficient derived from a statistical verification. W = bD+cD² was selected for the one-variable equation, while W = aD^bH^c was selected for the two-variable equation. The fit index of the former was 0.87-0.92, while that of the latter was 0.94-0.98, both of which showed a good fit. A new weight table was prepared using the optimal estimation formula, and it was compared and analyzed with a previous weight table. Analysis results showed that Gangwon pine had higher values in the previous weight table, while pines in the central region had higher values in the newly created weight table.

• Geotechnical Engineering
• /
• v.6 no.1
• /
• pp.43-58
• /
• 1990

In order to get ultimate pullout resistance of ground anchor, the position of failure surface, normal stress and friction angle on the failure surface should be known. In this study, the position of failure surface is obtained by observing deformation of ground around anchor, and stresses on the anchor surface are analyzed by measuring normal and shear stresses on the anchor surface through model anchor test in plane strain. In addition, the relationship between lateral earth pressure and the position of failure surface is analyzed and the formula for calculating ultimate pullout resistance of anchor is proposed by using non-dimensional coefficient of ultimate pullout resistance.

• Journal of Korean Medicine Rehabilitation
• /
• v.20 no.1
• /
• pp.91-107
• /
• 2010

Objectives : The purpose of this study was to investigate which herbs and herbal formulae are frequently used for the treatment of osteoporosis since 2000. Methods : We searched the CENTRAL, MEDLINE, AMED, CINAHL, Scopus, KISS, Korea MED, KERIS, Kmbase, Dbpia, J-STAGE, CNKI, J Oriental Rehab Med., J Korean Oriental Med., J Oriental Gynecol. using search key words osteoporosis, osteopenia, bone density and bone loss combined with herbal, botanical plant and phytomedicine. Results : 73 studies were reconfirmed and 83 herbs have been found. For single herb, most of them were categorized into Boyik-yak(補益藥, Buyi-yao). For herbal formulae, various herbal formulae are used. Calculating each herb in consisted in each herbal formula, Angelica Gigas Radix(當歸) and Rehmanniae Radix Preparat(熟地黃) turned out to be the most frequently used herb. Conclusions : Further studies regarding herbal medicines on osteoporosis are needed.

• Journal of the Korean Association of Geographic Information Studies
• /
• v.4 no.4
• /
• pp.51-60
• /
• 2001

This study analyzed fractal characteristics of river basin by using GIS. In this study, topographical factors in river basin was grid-analyzed for each cell size by using GIS and regression formula was derived by analyzing correlation among topographical factors and cell size which were calculated here. And, analysis of fractal characteristics of river by using the result calculated from 1) showed that among topographical factors, river length only increases according as cell size increases. The result of calculating fractal dimension for each cell size shows that river length, basin area, and centroidal flow path are 1.028, 1.0026 and 1.0061 respectively.

• Journal of the Korean Institute of Navigation
• /
• v.9 no.1
• /
• pp.41-81
• /
• 1985

Tidal phenomenon can be utilized by the wise and cautious mariner to safely perform his duties as pilot and navigator. It can be either a help or hindrance to the mariner. The principle of MULDAE which expresses the determination of the state of the tide based upon knowledge of the lunar date and it has been used in Korea since ancient times. The folk method of calculation was essentially based on an unsystematic division of the lunar month, traditionally using the numbers 7 or 8. As the lunar cycle is complete in 15 days the tidal cycle should also correspondence closely to the lunar date. This paper represents the first scientific attempt to systematically investigate this unique traditional method of tidal calculation and contains a comparison of the MULDAE and ordinary (solar based) tide calculation methods. MULDAE was compared with the standard tide table for standard and island ports in Korea from 1982 to 1985. This study concluded that MULDAE was indeed an accurate adn reliable predictor of tidal activity. Furthermore, the number 6 was found to be the correct divisor upon which to base MULDAE calculations Also a formula expressing MULDAE as a function was discovered. This research show that MULDAE can be applied nationwide and is a reliable and easy way to predict tides based upon mean figures for certain ports and island A calender showing MULDAE is presented here for the first time. A clear relationship between the MULDAE method of calculating tides and the use of ordinary tide tables is proven.

• Steel and Composite Structures
• /
• v.34 no.5
• /
• pp.769-782
• /
• 2020

A Prestressed stayed steel column is an efficient and lightweight way with regard to enhancing the stability behaviour of a compression column. In the past, researchers primarily concentrated on investigating the behaviour of stayed steel columns with horizontal crossarms. However, this article focuses on prestressed stayed steel columns with split-up crossarm system, in which the crossarms are aslant and rotational symmetrically arranged. A mathematical formula calculating the optimal pretension that corresponds to the maximum critical buckling load was established according to geometric analysis based on the small deformation assumption. It was demonstrated that critical buckling mode of this stayed column is different from the one with horizontal crossarms. The governing imperfection direction that should be adopted in the nonlinear buckling analysis was determined in this work. In addition, the effects of crossarm inclination, stay diameter, and crossarm length on the stability behaviour were investigated. An influencing factor denotes the ratio of the load carrying capacity of the prestressed stayed steel column to the Euler load of the main column was also obtained.

• Journal of the Korean Professional Engineers Association
• /
• v.18 no.3
• /
• pp.1-20
• /
• 1985

The traffic congestion of Seoul city has been one of the most serious problems to be settled since the advent of 1970s. As a means to mitigate traffic mess, the authority concerned launched the construction of subway line 3 and 4 in 1980. The two Subway lines slated for completion by 1985 cross each other and run north-south direction, passing through the metropolitan area of Seoul city fraught with high-rise edifices and large-scale shopping centers, and, in order to reduce blasting vibration, NATM was executed for a distance of 10 Km, instead of ASSM previously employed when subway line 1 and 2 were constructed. Tunnel blastings were implemented, preceded by classifying the rocks at construction area into five categories, namely, hard rock, semi-hard rock, weak rock weathered rock and silt and by calculating their respective specific charges through standard test blastings, by employing the pre-splitting and smooth blasting with drilling patterns of burn cut type, so as not to cause damages to surface structures. Most of explosives used were the slurry of low specific gravity and low velocity, and the firings executed by the use of milli-second detonators. Empiric formula were also formulated to check blasting vibrations, based on the vibration allowable values of West Germany standard, for the application to vulnerable construction zones. Should the two lines be placed for public service in 1985, about 40% of the total traffic population of Seoul city amounting to 15 million as of 1984 is estimated to be carried by subway with no difficulties.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.32 no.1
• /
• pp.130-136
• /
• 2009

Estimation of mortality behavior of a industrial property are useful for calculating depreciation and making management decisions relating to property. The common methods of computing depreciation require an estimation of service life, and some methods may require an estimate of life expectancy. Estimation of service life and life expectancy can be computed from a smoothed and extended life table of original life tables developed through life analysis techniques. Several actuarial techniques are available to construct a life table for depreciation application. Of these methods, the graphic approach and graduation by mathematical formula are the most widely used in the field of depreciation. A commonly used technique of smoothing and of extending the life table is to fit a lows type survivor curves to the observed retirement rate by the least square method. In this paper, estimates of depreciation rate based on directly observed data of the domestic petrochemical equipments are presented.

• Journal of the Korean Society of Clothing and Textiles
• /
• v.40 no.2
• /
• pp.330-341
• /
• 2016

This study suggested criterion for Petite-size and analyzed the body size and characteristics that were proper to manufacture clothing for Korean Petite-size women aged 18 to 34. It also analyzed size information about pattern making for Petite-size women through a comparison of the size and proportion of Petite-size with Regular-size. The criterion of Petite-size was decided in consideration of the distribution and perception of stature; subsequently, the stature range for Petite-size was defined as under 157.5cm. Body size and proportion of Petite-size were analyzed through calculating the mean from 25 to 75 percentiles of a Petite-size stature range. The Petite-size of this study was compared to KS Petite and total subjects through One way ANOVA. It was confirmed that the Petite-size of this study had body characteristics like KS Petite; however, Petite-size was larger in height and vertical length than KS Petite. The significant differences between Petite-size and Regular-size were identified in the same bust girth range, that required a revised calculation formula for pattern making that would be proper for Petite-size. It is expected that the Body size and proportion could be utilized as a reference for manufacturing or purchasing Petite-size clothing. The result of this study will contribute to enhance the fit satisfaction for Petite-size women aged 18 to 34.