• International Journal of Highway Engineering
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• v.6 no.2 s.20
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• pp.1-13
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• 2004

This study dealt with size effect of specimen in measuring deformation strength and estimating rut resistance of asphalt concretes under static loading using Kim test. Two aggregates, a normal asphalt (pen 60-80) and 6 polymer-modified asphalt (PMA) binders were used for preparation of 14 dense-graded mixtures. Mixtures were prepared based on optimum asphalt content by Marshall compactor (S= 10cm) and gyratory compactor (S= 15cm) for Kim test and for wheel tracking test. In statistical analysis by general linear model (GLM) procedure of SAS, the diameter of specimen was found not to be a significant factor that affect the Kim test result. Therefore, it was found that either loom-diameter or 15cm-diameter of specimen gave no significant difference in deformation strength ($K_D$) values in Kim test for any aggregate mixture. However, the thickness of specimen was found to be a significant factor in determining $K_D$. It is estimated that $K_D$ is a function of y, vertical deformation, and y has something to do with thickness of specimen. Therefore, it is suggested that the thickness of specimen should not be higher than 6.6cm, and the correction factor depending on the thickness value should be developed in the future study.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.10
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• pp.1147-1155
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• 2014

Biomechanical models are often used to predict muscle and joint forces in the human body. For estimation of muscle forces, the body and muscle properties have to be known. However, these properties are difficult to measure and differ from person to person. Therefore, it is necessary to predict the change in muscle forces depending on the body and muscle properties. The objective of the present study is to develop a numerical procedure for estimating the muscle forces in the human lower extremity under uncertainty of body and muscle properties during rising motion from a seated position. The human lower extremity is idealized as a multibody system in which eight Hill-type muscle force models are employed. Each model has four degrees of freedom and is constrained in the sagittal plane. The eight muscle forces are determined by minimizing the metabolic energy consumption during the rising motion. Uncertainty analysis is performed using a first-order reliability method. The one-standard-deviation range of agonistic muscle forces is calculated to be about 150-300 N.

• Journal of Korean Society of Transportation
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• v.19 no.5
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• pp.21-33
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• 2001

Intelligent Transport Systems (ITS) was first introduced in Korea early 1990's, and Korean government has put a lot of efforts for flourishing it in the entire nation. Regardless of these efforts, private participation is not active enough to accelerate ITS implementation in Korea. Expert group made every endeavor to analyze the current situation, and found out some phenomena. It may be summarized as two folds. Firstly, private sector has a lack of confidence on the future ITS market. Budget in the strategic plan is the only publication and guide that private sector can refer to, and it merely indicates deployment costs. Secondly, direction and procedure of R&D are not well defined. It implies that private sector takes too much risk when they invest for R&D. This research, therefore, focuses on the first issues. Concretely, the goal of the project was to establish and analyze the model for estimation the future ITS market side. Author reviewed both quantitative and qualitative models, and concluded that diffusion model in qualitative model was suitable for ITS market estimation. According to model calibration. it is estimated that 14 trillion Won was the market size in 2020 under normal condition. Impact of this result may seduce Information Technology(IT) related private companies into ITS market. Although this research couldn't cover various topics, it nay dedicate in boosting ITS in Korea. Also, it will be a good starting point for further study for the advancement of ITS.

• Journal of Korea Water Resources Association
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• v.38 no.10 s.159
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• pp.801-810
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• 2005

The lag time is one of the most important factors for estimating a flood runoff from streams. It is well known to be under the influence of the morphometric properties of basins which could be expressed by catchment shape descriptors. In this paper, the notion of the geometric characteristics of an equivalent ellipse proposed by Moussa(2003) is applied for calculating the lag time of geomorphological instantaneous unit hydrograph(GIUH) at the basin outlet. The lag time is obtained from the observed data of rainfall and runoff by using the method of moments suggested by Nash(1957), and the procedure based on geomorphology is used for GIUH. The relationships between the basin morphometric properties and the hydrological response are discussed as applied to 3 catchments In Korea. Additionally, the shapes of equivalent ellipse are examined how then are transformed from upstream area to downstream one. As a result, the relationship between the hydrological response and descriptors is shown to be comparatively good, and the shape of ellipse is presented to approach a circle along the river downwards. These results may be expanded to the estimation of hydrological response of ungauged catchment.

• The Journal of Engineering Geology
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• v.18 no.1
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• pp.17-26
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• 2008

In this study, the design method of slope reinforced by the earth retention systems were systematically developed, and the flow chart of design procedure fur each system were constructed to design the slope rationally. The proposed design method is composed of 5 steps such as field condition investigation step, slope design step, landslide occurrence prediction step, slope failure scale estimation step and reinforcement countermeasure selection step. The quantitative standard of slope failure scale was established based on the arrangement of various overseas standards which is estimating the slope failure, and the analysis of slope failure scale which is occurred in the country. The slope failure scale is classified into three categories the small scale of slope failure is less than $150m^3$ of slope failure volume, the middle scale of slope failure is from $150m^3$ to $900m^3$ and the large scale of slope failure is more than $900m^3$. The earth retention system could be selected by the proposed slope failure scale based on the slope failure volume. Meanwhile, the design methods of earth retention system such as piles, soil nails and anchors were developed. The optimal countermeasure for slope stability could be proposed using above design methods.

• The Journal of the Korea Contents Association
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• v.14 no.6
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• pp.367-384
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• 2014

This study addresses an empirical issue which has been received little attention in the contemporary finance literature: To identify any financial determinants of the profitability indices for the firms belonging to the Korean chaebol. Three hypotheses of concern were postulated and tested for the sample firms covering the periods of the pre-and post-financial global crises. Regarding the results on the 1st hypothesis test of characterizing any financial profiles for the firms (belonging to the chaebols) by estimating a legitimate panel data model: the present study found the statistically significant relationships of the explanatory variables (BVLEVl, MVLEVl, MV/BV, RISK, FCFF and FOS) with the book-value based profitability ratio: while the market-valued profitability index was explained only by BVLEV2. Regarding the 2nd hypothesis test for the profitability of the sample firms at the industry level: the chaebol firms in the chemical and the food industries overall positioned themselves into the top ranks in order, which was tested by the ANCOVA and the Tukey multiple comparison procedure. Finally: on the 3rd hypothesis test for the 'adjusted' Dupont system, only two such as the 'operating margin' and the 'asset turnover' showed their significant effects between the chaebol firms and their counterparts in both the (parametric) independent samples t-test and the (nonparametric) Wilcoxon-Mann-Whitney statistics.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.11
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• pp.128-134
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• 2016

Estimating the repair and reinforcement (R&R) costs for each bridge member is essential for managing the life cycle of a bridge using a bridge management system (BMS). Representative members of a bridge were defined in this study, and detailed and representative R&R methods for each one were drawn in order to develop a systematic maintenance cost model that is applicable to the BMS. The unit cost for each detailed R&R method was established using the standard of estimate and historical cost data, and a systematic procedure is presented using an integration program to enable easy renewal of the R&R unit cost. Also, the average unit cost of the representative R&R methods was calculated in the form of a weighted average by considering the unit cost and application frequency of each detained R&R method. The appropriateness of the drawn average unit cost was reviewed by comparing and verifying it with the previous historical unit cost. The suggested average R&R unit cost can be used to review the validity of the required budget or the appropriateness of the R&R performance cost in the stage to establish the bridge maintenance plan. The results of this study are expected to improve the reliability of maintenance cost information and the rationality of decision making.

• Journal of Korean Society of Rural Planning
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• v.21 no.2
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• pp.33-49
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• 2015

The objective of this study was to predict land use change based on the land use change scenarios for the Hwangguji river watershed, South Korea. The land use change scenario was derived from the representative concentration pathways (RCP) 4.5 and 8.5 scenarios. The CLUE (conversion of land use and its effects) model was used to simulate the land use change. The CLUE is the modeling framework to simulate land use change considering empirically quantified relations between land use types and socioeconomic and biophysical driving factors through dynamical modeling. The Hwangguji river watershed, South Korea was selected as study area. Future land use changes in 2040, 2070, and 2100 were analyzed relative to baseline (2010) under the RCP4.5 and 8.5 scenarios. Binary logistic regressions were carried out to identify the relation between land uses and its driving factors. CN (Curve number) and impervious area based on the RCP4.5 and 8.5 scenarios were calculated and analyzed using the results of future land use changes. The land use change simulation of the RCP4.5 scenario resulted that the area of urban was forecast to increase by 12% and the area of forest was estimated to decrease by 16% between 2010 and 2100. The land use change simulation of the RCP8.5 scenario resulted that the area of urban was forecast to increase by 16% and the area of forest was estimated to decrease by 18% between 2010 and 2100. The values of Kappa and multiple resolution procedure were calculated as 0.61 and 74.03%. CN (III) and impervious area were increased by 0-1 and 0-8% from 2010 to 2100, respectively. The study findings may provide a useful tool for estimating the future land use change, which is an important factor for the future extreme flood.

• Journal of Korean Society of Transportation
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• v.23 no.5 s.83
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• pp.147-155
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• 2005

The purpose of this paper is to develop a method for estimation of reliable path-travel time using data obtained from the toll collection system on freeways. The toll collection system records departure and arrival time stamps as well as the identification numbers of arrival and destination tollgates for all the individual vehicles traveling between tollgates on freeways. Two major issues reduce accuracy when estimating path-travel time between an origin and destination tollgate using transaction data collected by the toll collection system. First, travel time calculated by subtracting departure time from arrival time does not explain path-travel time from origin tollgate to destination tollgate when a variety of available paths exist between tollgates. Second, travel time may include extra time spent in service and/or rest areas. Moreover. ramp driving time is included because tollgates are installed before on-ramps and after off-ramps. This paper describes an algorithm that searches for arrival time when departure time is given between tollgates by a Progressive Iterative Forward and Backward (PIFAB) search method. The algorithm eventually produces actual path-travel times that exclude any time spent in service and/or rest areas as well as ramp driving time based on a link-based procedure.

• Journal of muscle and joint health
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• v.5 no.1
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• pp.83-109
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• 1998

This study was carried out to identify the Important modifiable risk factors for reduced bone mass and to construct prediction model which can classify women with either low or high bone mass. Through the literature review, individual characteristics such as age, body weight, height, education level, family history, age of menarche, postmenopausal period, gravity, parity, menopausal status, and breast feeding period were identified and factors of life style such as past milk consumption, past physical activity, present daily activity, present calcium intake, alcohol intake, cigarette smoking, coffee consumption were identified as influencing factors of reduced bone mass in women. Four hundred and eighty women aged between 28 and 76 who had given measurement bone mineral density by dual energy x-ray absortiometry in lumbar vertebrae and femur from July to October, 1997 at 4 general hospitals in Seoul and Pusan were selected for this study. Women were excluded if they had a history of any chronic illness such as rheumatoid arthritis, diabetes mellitus, hyperthroidism, & gastrointestinal disorder and any medication such as calcium supplements, calcitonin, estrogen, thyroxine, antacids, & corticosteroids known affect bone. As a result of these exclusion criteria, four hundred and seventeen women were used for analysis. Multiple logistic regression model was developed for estimating the likelihood of the presence or absence of reduced bone mass. A SAS procedure was used to estimate risk factor coefficient. The results are as follows For lumbar spine, the variables significant were age, body weight, menopause status, daily activity, past milk consumption, and past physical activity(p<0.01), while for femoral Ward's triangle, age, body weight, level of education, past milk consumption, past physical activity(p<0.001). Past physical activity, present daily activity and past milk consumption are the most powerful modifiable predictors in vertebrae and femur among the predictors. When the model performance was evaluated by comparing the observed outcome with predicted outcome, the model correctly identified 74.1% of persons with reduced bone mass and 84.5% of persons with normal bone mass in the lumbar vertebrae and 82.9% of persons with reduced bone mass and 75.0% of persons with normal bone mass in the femoral Ward's triangle. On the basis of these results, a number of recommendations for the management of reduced bone mass may be made : First, those woman who are classified as high risk group of the reduced bone mass in the prediction model should examine the bone mineral density to further examine the usefulness of this model. Second, the optimal amount of milk consumption and a regular weight bearing exercise in childhood, adolescence, and early adult should be ensured.