• Proceedings of the Korean Society for Rock Mechanics Conference
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• 2000.09a
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• pp.183-193
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• 2000

A series of studies such as geological logging data analysis, detailed geological survey, rock mass evaluation, in-situ and laboratory tests, rock strength and mechanical properties of the rock were concerned. The stability of the slope were carried out inorder to design the pit slope and individual benches using the stereographic projection analysis and numerical methods in Roto Pit of Pasir coal fetid. The bedding plane was one of the major discontinuities in the Roto Pit and the dip of which is about $60^{\circ}$in the northern part and $83^{\circ}$in the southern part. The dip of bedding becomes steeper from north to south. The plane and toppling failures are presented in many slopes. In laboratory test the average uniaxial compressive strength of mudstone was 9 MPa and that of weak sandstone was 10 MPa. In-situ test showed that the rocks of Roto north mining area are mostly weak enough to be classified in grade from R2(weak) to R3(medium strong weak) and the coal is classified in grades from R1(Very weak) to R2(Weak). The detailed stability analysis were carried out on 4 areas of Roto north(east, west, south and north), and 2 areas of Roto south(east and west). In this paper, the minimum factor of safety was set to 1.2 which is a general criterion for open pit mines. Using the stereographic projection analysis and the limit equilibrium method, slope angles were calculated as 30~$36^{\circ}$for a factor of safety greater than 1.2. Then these results were re-evaluated by numerical analysis using FLAC. The final slope angles were determined by rational described abode. A final slope of 34 degrees can guarantee the stability for the eastern part of the Roto north area, 33 degrees for the western part, 35 degrees for the northern part and 35 degrees for the southern part. For the Roto south area, 36 degrees was suggested for both sides of the pit. Once the pit slope is designed based on the stability analysis and the safety measures. the stability of 니ope should be checked periodically during the mining operations. Because the slope face will be exposed long time to the rain fall, a study such aspreventive measures against weathering and erosion is highly recommended to be implemented.

• Tunnel and Underground Space
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• v.10 no.3
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• pp.430-440
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• 2000

A series of studies such as geological logging data analysis, detailed geological survey, rock mass evaluation, in-situ and laboratory tests, rock strength and mechanical properties of the rock were concerned. The stability of the slope were carried out inorder to design the pit slope and individual benches using the stereographic projection analysis and numerical methods in Roto Pit of Pasir coal field. The bedding plane was one of the major discontinuities in the Roto Pit and the dip of which is about 60$^{\circ}$ in the northern part and 83$^{\circ}$ in the southern part. The dip of bedding becomes steeper from north to south. The plane and toppling failures are presented in many slopes. In laboratory test the average uniaxial compressive strength of mudstone was 9MPa and that of weak sandstone was 10MPa. In-situ test showed that the rocks of Roto north mining area are mostly weak enough to be classified in grade from R2(weak) to R3(medium strong weak) and the coal is classified in grades from R1(Very weak) to R2(Weak). The detailed stability analysis were carried out on 4 areas of Roto north (east, west, south and north), and 2 areas of Roto south(east and west). In this paper, the minimum factor of safety was set to 1.2 which is a general criterion for open pit mines. Using the stereographic projection analysis and the limit equilibrium method, slope angles were calculated as 30∼36$^{\circ}$ for a factor of safety greater than 1.2. Then these results were re-evaluated by numerical analysis using FLAC. The final slope angles were determined by rational described above. A final slope of 34 degrees can guarantee the stability for the eastern part of the Roto north area, 33 degrees for the western part, 35 degrees for the northern part and 35 degrees for the southern part. For the Roto south area, 36 degrees was suggested for both sides of the pit. Once the pit slope is designed based on the stability analysis and the safety measures, the stability of slope should be checked periodically during the mining operations. Because the slope face will be exposed long time to the rain fall, a study such aspreventive measures against weathering and erosion is highly recommended to be implemented.

• Journal of IKEEE
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• v.18 no.4
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• pp.552-558
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• 2014

This paper suggests how to design a ZigBee-chip-based communication module to remotely measure radiation level. The suggested communication module consists of two control processors for the chip as generally required to configure a ZigBee system, and one chip module to configure a ZigBee RF device. The ZigBee-chip-based communication module for remote radiation measurement consists of a wireless communication controller; sensor and high-voltage generator; charger and power supply circuit; wired communication part; and RF circuit and antenna. The wireless communication controller is to control wireless communication for ZigBee and to measure radiation level remotely. The sensor and high-voltage generator generates 500 V in two consecutive series to amplify and filter pulses of radiation detected by G-M Tube. The charger and power supply circuit part is to charge lithium-ion battery and supply power to one-chip processors. The wired communication part serves as a RS-485/422 interface to enable USB interface and wired remote communication for interfacing with PC and debugging. RF circuit and antenna applies an RLC passive component for chip antenna to configure BALUN and antenna impedance matching circuit, allowing wireless communication. After configuring the ZigBee-chip-based communication module, tests were conducted to measure radiation level remotely: data were successfully transmitted in 10-meter and 100-meter distances, measuring radiation level in a remote condition. The communication module allows an environment where radiation level can be remotely measured in an economically beneficial way as it not only consumes less electricity but also costs less. By securing linearity of a radiation measuring device and by minimizing the device itself, it is possible to set up an environment where radiation can be measured in a reliable manner, and radiation level is monitored real-time.

• Journal of Korean Society of Forest Science
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• v.65 no.1
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• pp.80-91
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• 1984

The purposes of this study are to analyze and forecast the domestic demand for papers by regression models with time-series data (1965-81). For the period of 1965-81, the real GNP of Korea grew at annual average increase rate of 8.8 percent. On the other hand, the domestic demand of papers grew at annual average increase rate of 17.9 percent in this period. Especially, the annual average increase rate for board-papers accounted to 25.8 percent. To analyze domestic demand for papers, GNP, per capita GNP, price findex of papers, production activity index of the major papers consuming industries and price index of substitutive goods were selected as independent variables. The expected values of domestic demand for papers were computed by forecasting equations as follows. T-values are in parentheses. ${\ell}nDDP=2.452+1.986{\ell}nPG-0.844{\ell}nPWI$ $(33.397)^*\;(-6.149)^*\;R^2=0.997$ ${\ell}nDDP=6.468+0.827{\ell}nPDA$ $(17.403)^*\;R^2=0.950$ DDP : Domestic demand for papers PG : Real GNP per capita (1,000 won) PWI : Real price index of papers (1980 = 100) PDAV : Production activity index of the major papers consuming industries The results analyzed and forecasted by these models are summarized as follows: The domestic demand for papers had positive correlation toward per capita GNP and production activity index of the major papers consuming industries. Per capita GNP elasticity of the domestic demand for papers was the most elastic among independent variables. The price elasticity of domestic demand for papers had negative sign and inelastic. These were not only statistically significant but theoretically compatible. The domestic demand for papers was projected to be 3,152-4,470 thousand mit in 1991, representing at annual increase rate of 5.0-12.4 percent during the period of 1982-91. Domestic demand for papers per capita was projected to be 69.1-98.0 kg in 1991.

• Asia pacific journal of information systems
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• v.21 no.4
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• pp.45-62
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• 2011

The notion of information systems (IS) continuance has recently emerged as one of the most important research issues in the field of IS. A great deal of research has been conducted thus far on the basis of theories adapted from various disciplines including consumer behaviors and social psychology, in addition to theories regarding information technology (IT) acceptance. This previous body of knowledge provides a robust research framework that can already account for the determination of IS continuance; however, this research points to other, thus-far-unelucidated determinant factors such as habit, which were not included in traditional IT acceptance frameworks, and also re-emphasizes the importance of emotion-related constructs such as satisfaction in addition to conscious intention with rational beliefs such as usefulness. Experiences should also be considered one of the most important factors determining the characteristics of information system (IS) continuance and the features distinct from those determining IS acceptance, because more experienced users may have more opportunities for IS use, which would allow them more frequent use than would be available to less experienced or non-experienced users. Interestingly, experience has dual features that may contradictorily influence IS use. On one hand, attitudes predicated on direct experience have been shown to predict behavior better than attitudes from indirect experience or without experience; as more information is available, direct experience may render IS use a more salient behavior, and may also make IS use more accessible via memory. Therefore, experience may serve to intensify the relationship between IS use and conscious intention with evaluations, On the other hand, experience may culminate in the formation of habits: greater experience may also imply more frequent performance of the behavior, which may lead to the formation of habits, Hence, like experience, users' activation of an IS may be more dependent on habit-that is, unconscious automatic use without deliberation regarding the IS-and less dependent on conscious intentions, Furthermore, experiences can provide basic information necessary for satisfaction with the use of a specific IS, thus spurring the formation of both conscious intentions and unconscious habits, Whereas IT adoption Is a one-time decision, IS continuance may be a series of users' decisions and evaluations based on satisfaction with IS use. Moreover. habits also cannot be formed without satisfaction, even when a behavior is carried out repeatedly. Thus, experiences also play a critical role in satisfaction, as satisfaction is the consequence of direct experiences of actual behaviors. In particular, emotional experiences such as enjoyment can become as influential on IS use as are utilitarian experiences such as usefulness; this is especially true in light of the modern increase in membership-based hedonic systems - including online games, web-based social network services (SNS), blogs, and portals-all of which attempt to provide users with self-fulfilling value. Therefore, in order to understand more clearly the role of experiences in IS continuance, analysis must be conducted under a research framework that includes intentions, habits, and satisfaction, as experience may not only have duration-based moderating effects on the relationship between both intention and habit and the activation of IS use, but may also have content-based positive effects on satisfaction. This is consistent with the basic assumptions regarding the determining factors in IS continuance as suggested by Oritz de Guinea and Markus: consciousness, emotion, and habit. The principal objective of this study was to explore and assess the effects of experiences in IS continuance, with special consideration given to conscious intentions and unconscious habits, as well as satisfaction. IN service of this goal, along with a review of the relevant literature regarding the effects of experiences and habit on continuous IS use, this study suggested a research model that represents the roles of experience: its moderating role in the relationships of IS continuance with both conscious intention and unconscious habit, and its antecedent role in the development of satisfaction. For the validation of this research model. Korean university student users of 'Cyworld', one of the most influential social network services in South Korea, were surveyed, and the data were analyzed via partial least square (PLS) analysis to assess the implications of this study. In result most hypotheses in our research model were statistically supported with the exception of one. Although one hypothesis was not supported, the study's findings provide us with some important implications. First the role of experience in IS continuance differs from its role in IS acceptance. Second, the use of IS was explained by the dynamic balance between habit and intention. Third, the importance of satisfaction was confirmed from the perspective of IS continuance with experience.

• Journal of Hospice and Palliative Care
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• v.21 no.1
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• pp.23-32
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• 2018

Purpose: Little is known regarding the extent to which dying patients with chronic obstructive pulmonary disease (COPD) receive life-sustaining procedures and palliative care in U.S. hospitals. We examine hospital cost trends and the impact of palliative care utilization on the use of life-sustaining procedures in this population. Methods: Retrospective nationwide cohort analysis was performed using National Inpatient Sample (NIS) data from 2005 and 2014. We examined the receipt of both palliative care and intensive medical procedures, defined as systemic procedures, pulmonary procedures, or surgeries using the International Classification of Diseases, 9th revision (ICD-9-CM). Results: We used compound annual growth rates (CAGR) to determine temporal trends and multilevel multivariate regressions to identify factors associated with hospital cost. Among 77,394,755 hospitalizations, 79,314 patients were examined. The CAGR of hospital cost was 5.83% (P<0.001). The CAGRs of systemic procedures and palliative care were 5.98% and 19.89% respectively (each P<0.001). Systemic procedures, pulmonary procedures, and surgeries were associated with increased hospital cost by 59.04%, 72.00%, 55.26%, respectively (each P<0.001). Palliative care was associated with decreased hospital cost by 28.71% (P<0.001). Conclusion: The volume of systemic procedures is the biggest driver of cost increase although there is a cost-saving effect from greater palliative care utilization.

• KDI Journal of Economic Policy
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• v.31 no.1
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• pp.105-138
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• 2009

Although the decline in fertility rate is generally observed along the history of economic development throughout the world, the continuing decline hitting below the replacement level in Korea over the recent years gathered serious social concerns on the ground that it accelerates the process of population aging. The total fertility rate in Koreareached 2.08 in 1983, and gradually fell to the levels of 1.08 in 2005 and 1.26 in 2007. The policy debate over the role of the government has been focused mainly on the level of theoretical discussion without substantial basis on firm empirical evidence and the determinants of fertility. The objective of the paper is to empirically investigate the fertility effect of the female wage, which is understood as one of the most important determinants of fertility in Koreasince 1980 focusing on one aspect of fertility, namely birth spacing. Using the Korean National Fertility Survey conducted in 2006, I estimate a duration model of first and second births taking into account individual heterogeneity, which turned out to be an important factor to control for. Compared with previous studies in the literature on the Korean fertility, the study has an advantage of using the complete pregnancy history of women in a more representative sample. Unlike the previous studies, the analysis also deals with the endogeneity of marriage by treating a certain age, rather than age at marriage, as the time in which a woman becomes exposed to the risk of pregnancy. The study shares the common problem in the literature on birth spacing of lacking relevant wage information for respondents in a retrospective survey. I estimate the wage series as a function of the basic characteristics using the annual Wage Structure Survey from 1980 to 2005, which is considered as a nationally representative sample for wage information of employees. The results suggest that the increase in female wage by 10 percent leads to a decrease in second birth hazard by 0.56~0.92 percentage points and that the increase in spouse's wage by the equal amount is accompanied by the increase in second birth hazard by 0.36~1.13 percentage points. These estimates are more precisely estimated and of smaller magnitude than those presented by the previous studies. The results are robust to the different specifications of the wage equation. The simulation analysis based on the predicted values shows that about 17% of the change in the second birth hazard over the period 1980 to 2005 was due to the change in the female wage. Although there is some limitation in data, the results can be viewed as one estimate of the role of female wage on the recent fertility decline in Korea. The question raised by the paper is not a normative one of whether a government should promote childbearing but a positive one thatexplains fertility decline. Therefore, if there is a wide consensus on promoting childbearing, the finding suggests that the policies designed to reduce the opportunity cost of women in the labor market would be effective. The recent movement of implementing a wide range of family-friendly policies including child care support, maternity leave, parental leave and tax benefit in developed countries should be understood in this context.

• Korean Journal of Environment and Ecology
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• v.34 no.2
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• pp.170-178
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• 2020

There are few landscape ecological analyses of Khingan fir (Abies nephrolepis) and other habitats of the sub-alpine zone in South Korea. In this study, we tried to quantitatively interpret and assess the habitat characteristics by analyzing 15 landscape indices according to the differences in tree layer coverage, in the Khingan fir habitat growing naturally in the sub-alpine zone of Seoraksan National Park. It was difficult to identify the tendency of landscape ecology to increase and decrease the tree layer coverage in the study site, which was the entire Khingan fir habitat in Seoraksan National Park. However, the Khingan fir habitat was found to be generally low in coverage, and population density as the tree layer coverage of less than 50 percent accounts for 85 percent of the total habitat. Moreover, the Khingan fir habitat in the 10 to 50 percent range was fragmented into a total of 286 patches, making it relatively less connected to the habitat. The total edge length and edge density, which could determine the edge effect of the main part according to the physical form, were the highest in the habitat of 26 to 50 percent coverage, indicating a relatively high impact from outside than habitats of other coverages. The shape with the tree layer coverage of between 10 and 50 percent was more complex even with patches of the same size, and it is believed that these characteristics make it more susceptible to habitat fragmentation and external confounding. We expect that the results of this study can be useful for time series analysis of spatial expansion or reduction of the Khingan fir habitat in Seoraksan National Park and provide the reference data for the morphological change and movement of patches and the connectivity and break-off between forests.

• Geophysics and Geophysical Exploration
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• v.3 no.1
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• pp.1-6
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• 2000

The 1 $km^2$ area studied is located in Sukchun-ri, Hwasung-koon, the southern part of Kyeonggi-do. Even though this site has been known as a contaminated area caused by seawater intrusions, geophysical and geochemical surveys have never been carried out at the site to determine the extent of the seawater contamination and to investigate whether the seawater intrusion is in progress. The purpose of this study is to determine the extent of seawater contamination and a preferred channel of the seawater intrusion using geophysical methods such as DC resistivity surveys with Schlumberger array and a dipole-dipole array. In order to determine whether the seawater intrusion is in progress in the area, DC resistivity monitoring with Schlumberger array was performed. According to the resistivity map obtained from the inversion of the resistivity data measured with Schlumberger array, the study area is divided into two districts as relatively lowly resistive (less than 30 ohm-m) and highly resistive (more than 30 ohm-m) areas. The distribution of the lowly resistive area is consistent with the distribution of the layer composed of clay minerals, and the resistivity of this layer decreases slowly as approaching to the old seashore. Hydrogeological analysis shows that the clay layer within a distance of about 200 m from the seashore has been already contaminated by sea-water and its electric conductivity is 8 times higher than that of the sand layer covered by the clay layer. According to the results of the 2-dimensional DC resistivity surveys with a dipole-dipole array, there are two preferred channels of the seawater intrusion in the site, and both the channels are in the NW-SE direction from the old seashore. The lowly resistive zone in the southern channel extends to a depth of 80 m. The DC resistivity monitoring with Schlumberger array was carried out along the preferred channel which has the low resistivity Bone (fracture zone) that extended to a depth of 80 m. The time series of apparent resistivity, measured at a distance of 260 m from the old coast line, fluctuates with a period of 12 hours. From these observations, it can be concluded that the seawater intrusion caused by tidal action is still in progress along the fractured zone interpreted by the DC resistivity surveys with a dipole-dipole array.

• Journal of the Korean earth science society
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• v.30 no.6
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• pp.721-733
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• 2009

A pattern of tropical cyclone (TC) movement in the western North Pacific area was studied using the empirical orthogonal function (EOF) and the best track data from 1951 to 2007. The independent variable used in this study was defined as the frequency of tropical cyclone passage in 5 by 5 degree grid. The $1^{st}$, $2^{nd}$ and $3^{rd}$ modes were the east-west, north-south and diagonal variation patterns. Based on the time series of each component, the signs of first and second mode changed in 1997 and 1991, respectively, which seems to be related to the fact that the passage frequency was higher in the South China Sea for 20 years before 1990s, and recent 20 years in the East Asian area. When the eigen vectors were negative values in the first and second modes and TC moves into the western North Pacific, TC was formed mainly at the east side relatively compared to the case of the positive eigen vectors. The first mode seems to relate to the pressure pattern at the south of Lake Baikal, the second mode the variation pattern around $30^{\circ}N$, and the third mode the pressure pattern around Japan. The first mode was also closely related to the ENSO and negatively related to the $Ni\tilde{n}o$-3.4 index in the correlation analysis with SST anomalies.