• The Korean Journal of Applied Statistics
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• v.34 no.5
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• pp.685-696
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• 2021

The Korean Economically Active Population Survey (KEAPS) is a national survey that produces employment-related statistics. The main purpose of the survey is to find out the economic activity status (employed/ unemployed/ non-employed) of the people. KEAPS has a unique characteristics caused by the survey method. In this study, through understanding of structural non-response and utilization of past data, we would like to present an improved imputation model. The performance of the proposed model is compared with the existing model through simulation. The performance of the imputation models is evaluated based on the degree of mathing/nonmatching rates. For this, we employ the KEAPS data in November 2019. For the randomly selected ones among the total 59,996 respondents, the six explanatory variables, which are critical in determining the economic activity states, are treated as non-response. The proposed model includes industry variable and job status variable in addition to the explanatory variables used in the precedent research. This is based on the linkage and utilization of past data. The simulation results confirm that the proposed model with additional variables outperforms the existing model in the precedent research. In addition, we consider various scenarios for the number of non-responders by the economic activity status.

• Journal of Korean Society of Transportation
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• v.30 no.4
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• pp.21-32
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• 2012

Exclusive bus lane (EBL) is typically located in the roadway median, and is accessed by weaving across the GPLs(general purpose lanes) before entering from the left lane of the GPLs. To maximize the potential for successful EBL operations, a critical design issue that requires special attention is the length of bus weaving section before entering EBL. The process of developing guidelines for the length of bus weaving section can be supported by a sensitivity analysis of performance measure (safety) with respect to the bus weaving distance. However, field data are difficult to obtain due to inherent complexity in creating performance measure (safety) samples under various interesting flows and bus weaving distance that are keys to research success. In this paper, VISSIM simulation is applied to simulate the operation of roadway weaving areas with EBL, and based on vehicle trajectory data from microscopic traffic simulation models, the Surrogate Safety Assessment Model (SSAM) computes the number of surrogate conflicts (or degree of safety) with respect to the bus weaving distance. Then, a multiple linear regression (MLR) model using safety data (number of surrogate conflicts) is developed. Finally, guidelines for bus weaving distance are established based on the developed MLR. Developed guidelines explicitly indicate that a longer bus weaving distance is required to maintain desired safety as weaving volume increases.

• Journal of the Korean Association of Geographic Information Studies
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• v.25 no.4
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• pp.136-150
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• 2022

In this study, a comparative review was conducted on how to use RGB images to obtain river topographic information, which is one of the most essential data for eco-friendly river management and flood level analysis. In terms of the topographic information of river zone, to obtain the topographic information of flow section is one of the difficult topic, therefore, this study focused on estimating the river topographic information of flow section through RGB images. For this study, the river topography surveying was directly conducted using ADCP and RTK-GPS, and at the same time, and orthomosiac image were created using high-resolution images obtained by drone photography. And then, the existing developed regression equations were applied to the result of channel topography surveying by ADCP and the band values of the RGB images, and the channel bathymetry in the study area was estimated using the regression equation that showed the best predictability. In addition, CCHE2D flow modeling was simulated to perform comparative verification of the topographical informations. The modeling result with the image-based topographical information provided better water depth and current velocity simulation results, when it compared to the directly measured topographical information for which measurement of the sub-section was not performed. It is concluded that river topographic information could be obtained from RGB images, and if additional research was conducted, it could be used as a method of obtaining efficient river topographic information for river management.

• 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 Korean association of regional geographers
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• v.16 no.1
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• pp.1-15
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• 2010

A feng-shui map(山圖) represents the most ideal natural landform on a map of feng-shui space model, highlighting propitious spots and grave sites in terms of feng-shui. This study made an analysis into feng-shui maps featured in the Chinese feng-shui manual Jiriinjasuji published in the Ming dynasty of China and did research on the following points regarding the traits of landform expressions: viewpoints of feng-shui maps, perspective points, center-oriented maps, double map scales, mountain theories, detailed expressions of propitious spots, etc. The major characteristics of landform expressions in the Chinese feng-shui manual Jiriinjasuji are as follows: the viewpoint technique was aerial one; the maps were center-oriented, that is to say, the center of grave sites or propitious spot was depicted in detail; and often the important terrains around grave sites were exaggerated or delete compared with real landforms. In addition, other vital landforms not observed from grave sites were depicted with viewpoints moved and were represented in greater details' The part of mountain theories had the following points as their main subject matter: geographical locations, overall orientations of mountain ranges, topographical traits, grave seat directions, surrounding terrains and extent of fortune-bringing. The directions of the maps were relative and there was no definite concept of scales. But, there are many cases where the maps made use of the double scale technique when expressing the terrains that have propitious space, logistical cities or directional importance. Furthermore, they often utilized multiple scale in expressing near views, mid-range views and distant views.

• Journal of Korean Society of Forest Science
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• v.101 no.1
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• pp.36-45
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• 2012

Education on the environment and plants offered by arboretum for today's people not only contribute to foster a better natural environment in urban region but also provide visitors with decent refreshment environment and beyond. In the study, the author undertook the observation on usage behavior and satisfaction model of arboretum visitors expect and investigated the facilities and programs to be offered by arboretum in order to propose the opinion regarding the service. For observation size of variables in a multiple regression analysis of variables is influencing satisfaction rankings walks the line of flow, the educational effect on the environment, cleanliness of the facility, visits pay, natural beauty, diversity of trees, accessibility and friendliness of staff, expansion of facilities in the arboretum and appeared as a complement. In case of visitor attribute, the residents living near the facility showed the highest visit frequency of more than 5 times, especially as part of taking a walk. This proves that the visit to arboretum is considered as part of everyday life, and thus a new program and walk path as well as movement route are needed to be developed for the visitors. In the question relating to the facilities and operation programs in Daegu Arboretum, particularly the requests by visitors, they responded that the establishment of cultural event, beautiful natural scenery, refreshment and convenience facilities is the most critical issue. In addition, the management on withered trees and bare lands is an urgent issue as well. In this sense, the Operation and Management Strategies based upon the visitor behaviors and model of satisfaction are needed to deal with the adoption of diverse events and festivals joined by local residents, ombudsman program, environmental program development for students and teachers within the region, negligent bare lands and withered tree replacement, and cafeteria facility improvement and supplement as well as the bench marking of other facilities than arboretums located in other regions. These items are thought to be sufficiently dealt with by Daegu Arboretum having no more external resources. It is recognized that the visitor satisfaction begins from a minor thing, and a small difference determines a great satisfaction, and thus the software approach rather than hardware one is in need.